saeon proef 5 - front-part 3 · the mandate of the south african environmental observation network...

SECTION 4

��

Published by SUN MeDIA Stellenbosch under the SUN PRESS imprint.

All rights reserved.

�� !��"��#��"��#��!$�� %��DST or SUN MeDIA.

Copyright © 2011 Authors and SUN MeDIA Stellenbosch

��&��%��"��%��"��"��"��%��%��'�%��(��%��)��%�� "��%��&��permission by the publisher.

*�� +,--

(�/��345)-)3+,665)+7)7

��8��9��--:-6;��"��<�"��=��>��?��@��;��)�� "��=��/��

�B��9F��*F(;��B��?�#(�$��%��$�

��$��$��$>��$��)�)��$��$>�

RIGHT Grasslands�[Barend Erasmus]

ENVIRONMENTAL

in South Africa

Change

�� =�FFK�O(��?��

Observations on

Editorial Committee

QVWX\^_�=$��=`\\f!�O^Vjkq`W��

wxz`W�;$�9`{|?��"��"�#��%��

�}~V\j��$��`W�w``\k�V}X9��;��%��F*

�xW\`X�w$��VkkV}kF��F��"�B��%

?��(�� %�;�(F

F(8Q�� F��*��"��/��

��

SECTION 4 – STATES AND TRENDS IN THE AQUATIC ENVIRONMENT ......... 179

;��"��"��9�� ................... ��+66

B��"�?��9��")�� "�� ........................................ � +65�

Q�� "�� ............................................................................ ��+7+

�� ......................... ��+74

;��"�� ............. ��+�+

=��"�)�� ;�� .................................................... ��+�4

MARINE OFFSHORE ENVIRONMENT ................................ 262

(�� ............................................................................ ��+�6

�� .................................................. ��+�7

��"��"��;�� ..................... ��+�5

;��"�� "�� ....................................................... ��+4,

��'�� ......................................................... � +46

AFTERWORD ............................................................................................................ 276

REFERENCES ............................................................................................................. 282

CONTRIBUTING AUTHORS ................................................................................ 299

PHOTOGRAPHIC CREDITS ................................................................................. 303

FRESHWATER AND ESTUARINE SYSTEMS ......................... 180

(�� ............................................................................ � -5-�

��"��"�� .................................................................... ��-56

��'�� .............................. � -54�

;��"��"��&��'�� ............................................................................ ��-3,

�� ...... ��-36

��F��Q��9��"�� ........................... ��-34

�� )�� "��"� ��"��"��"�� .......................... � +,-

MARINE INSHORE ENVIRONMENT .................................. 210

(�� ............................................................................ ��+--

;��"�%�� >��"��%�� .......................................................... ��+-+

�� "�� .............................................................. ��+-4

��+,,�)+,,4��O��)�� ......................................................................... ��+++

��;��(�� ........... ��++4

The mandate of the South African Environmental Observation Network (SAEON) is to establish and maintain state-of-the-art observation and monitoring sites and systems; drive and facilitate research on long-term change of South Africa’s terrestrial biomes, coastal and marine ecosystems; develop and maintain collections of accurate, consistent and reliable long-term environmental databases; promote access to data for research and/or informed decision making; and contribute to capacity building and education in environmental sciences. Its vision is: A comprehensive, sustained, coordinated and responsive South African environmental observation network that delivers long-term reliable data for scientific research, and informs decision-making for a knowledge society and improved quality of life. SAEON’s scientific design is adaptively refined to be responsive to emerging environmental issues and corresponds largely with the societal benefit areas of the intergovernmental Group on Earth Observations (GEO).

SAEON The Woods InformationBuilding C, Ground Floor Eva Mudau41 De Havilland Crescent Tel: +27 (12) 349 7722Persequor Technopark Email: [email protected] 0020

The vision of the Department of Science and Technology (DST) is to create a prosperous society that derives enduring and equitable benefits from science and technology. Our mission is to develop, coordinate and manage a national system of innovation that will bring about maximum human capital, sustainable economic growth and improved quality of life. We are guided by the corporate values of professionalism and competence. We will strive to deliver top-class, quality products and services, seek innovative ways to solve problems and enhance effectiveness and efficiency. The DST strives toward introducing measures that put science and technology to work to make an impact on growth and development in a sustainable manner in areas that matter to all the people of South Africa.

DST BuildingCSIR South Gate Entrance Meiring Naude Road SCIENTIA 0001

Tel: +27 (12) 843-6300

�Q(��9B/=(;��(��;�??(��(��#�/K��(�Q�*B�#(�8�*F�?��Q��#�9�F�?�� *� �;(��;�� #� ��;Q��=�8K� �#��!�� #��$

11

The idea for this book came from Albert van Jaarsveld. He discussed the possibility of a ‘coffee table book’ showing ‘before and after’ images of environmental changes in South Africa with Johan Pauw, who saw the relevance and necessity for such a book and its value for promoting the work of the South African Environmental Observation Network (SAEON), especially amongst politicians and decision makers, who by the nature of their work may not have much time to delve into the intricacies of scientific papers on environmental change, but need to advance sustainable policies for development. Together with Konrad Wessels, they developed the idea and approached me to act as project co-coordinator and to test the feasibility of the idea and set out a proposed table of content. Together we drafted a document listing broad topics or themes to be addressed and then went about listing potential contributors from the scientific and research community in South Africa. I then drafted a document formulating the goals that we would like to achieve and the approach to be followed by contributors to the proposed book. The potential authors were contacted and invited to participate in writing a book on ‘Earth observation and environmental change in South Africa’. The scientific and research community responded positively to the idea and a set of guidelines were sent to those willing to contribute to this publication. These authors sent in proposed titles and abstracts of what they had in mind. Their submissions were evaluated and most were accepted for inclusion. The vast majority of these authors honoured their commitments and submitted their full texts within a reasonable timeframe. A tentative table of contents was drawn up and circulated. Valuable inputs, especially from Sue Milton, led to a revised, restructured and reordered table of content very similar to the final version. Barend Erasmus, Charles Griffiths, Lauri Laakso, Johann Lutjeharms, Matlala Moloko, Sue Milton, André Theron, Rudie van Aarde, Brian van Wilgen and Alan Whitfield generously supplied supplementary photographs.

Acknowledgements

The book that has materialised from this process is probably not quite what Albert van Jaarsveld had in mind. It took on a life of its own, in spite of my best efforts to keep it in line with out initial intentions! Although every effort was made to ensure that it would be ‘... an attractive, richly illustrated and easily readable book on the causes consequences and responses to environmental changes in South Africa’, its scientific nature became much more prominent. We now have a publication ‘... conveying scientific evidence based on local case studies using examples to graphically illustrate these trends and impacts with a variety of satellite imagery, photo’s, maps and other illustrative materials.’The book gives a picture of environmental change and proposed responses on a range of themes and topics. It draws together work from as many scientific disciplines as possible, extracts the most pertinent information and presents it in a condensed format. As such this book should be very useful to inform the general public and senior political and public executive officials involved in policy formulation and decision making on environmental issues and implications of policies as initially intended. However, it will undoubtedly also be of value to lecturers and students at institutions of higher education.I would like to acknowledge the time and efforts of all the authors and co-authors who graciously contributed their work without remuneration in the interests of science and our fragile environment. I also thank the editorial committee (Johan Pauw, Albert van Jaarsveld and Konrad Wessels) for their foresight, confidence and support in helping to bring this publication to fruition.

Hendrik L Zietsman Editor

December, 2010

South Africa has a rich history of scientific excellence and of undertaking pioneering work in the environmental sciences. This richly illustrated publication is yet another valuable contribution to that heritage. According to a report by Thomson Reuters, between 2004 and 2008 South Africa ranked above average in the scientific fields of Environment and Ecology, contributing 1,29% of world output, with a citation rate averaging above 5 per paper. South Africa can also be proud of its strong tradition of exploiting scientific knowledge to support effective policy and practice in sustainable development. Supported by my department, the South African Environmental Observation Network (SAEON) emerged from that tradition to establish six strategic nodes that jointly cover South Africa and its adjacent oceans. These nodes function as observation systems and platforms that enable the environmental sciences community to perform longitudinal studies of environmental change, and ultimately to support sustainable development objectives. This work has made a valuable contribution to science-based initiatives such as the Southern African Millennium Ecosystem Assessment in identifying possibilities for improving human wellbeing, taking into account the capacity of ecosystem services to support these improvements. South Africa continues to face crucial social and economic challenges. A set of 12 priority outcomes has been identified for focused attention over the next few years. Effective management of our natural environment and assets is not only a key outcome in its own right, but also has an important contribution to make in supporting outcomes such as a long and healthy life for all South Africans, food security for all, and sustainable human settlements.

Foreword?\k�8$�$?$�9`WXx\%�?9

2

3

The natural environment is a complex system with many interconnected strands. A range of human pressures combine with natural processes resulting in many and varied impacts and responses. Science investments are vital for the development of a knowledge base that can assist decision-makers to make sense of the complexity and to respond through policy measures and interventions. Science investments range from the development of long-term environmental observation capabilities, the effective integration of new and existing datasets and the initiation of longitudinal studies, to ensuring maximum exploitation of the data through appropriate knowledge products such as forecasts, early warning systems and impact maps. Notwithstanding the strong foundation in environmental observation and research that already exists in South Africa, the Department of Science and Technology continues to prioritise this area for further development and investment within the context of its Innovation Plan. For example, we have committed to the development of satellites that will provide fine resolution and space-based data that we can exploit for areas ranging from environmental management to early warning systems for better disaster management. Over the next 10 years, through the Space Science Grand Challenge, we will be investing in satellites as well as supporting infrastructure that will constitute a stronger earth observation system. Coupled to these efforts are a range of other initiatives, under the umbrella of the Global Change Grand Challenge, which will support analysis and research on the basis of the available observation data sets as well as building a new generation of skilled scientists and practitioners.

I would like to take this opportunity to congratulate the National Research Foundation, SAEON and the many scientists who contributed their time and expertise to this publication and to the work being done to maintain and strengthen our environmental science heritage. More importantly, I would like to acknowledge the attempts being made to enhance the accessibility of complex and technical scientific material in ways that empower all sections of society.

Mrs G.N.M. Pandor, MPMinister of Science and Technology

December, 2010

3

555555555555555555

wxz`W�;$�9`{|QVWX\^_�=$�O^Vjkq`W

�}~V\j��$��`W�w``\k�V}X�xW\`X�w$��VkkV}k

Environmental conditions on earth are changing rapidly. The degree to which these changes are human-induced could be debated, but the fact that changes are taking place is indisputable. As custodians of finite natural resources we do not have the luxury of being complacent. This highly illustrative book provides a glimpse into the environmental changes that have been observed. It is not a compendium of all changes, as that would require numerous volumes. The book highlights some pertinent aspects of environmental change and introduces ways in which satellite technologies and other observation systems are used to measure and monitor some of these changes. In many cases, the book describes the principle problems and discusses why these issues are considered problematic. The book also describes the main drivers of these changes, how the environment is responding, and how these problems can be solved. In addition, the book outlines the potential consequences of failing to act.

Why a book about environmental change in South Africa?

The key understanding that the reader will gain from reading this book is that scientific observation of environmental change is ubiquitous in South Africa and that these changes are progressively affecting the future of South Africans through their combined impacts on human livelihoods, security and prosperity. A conscious effort is made to distinguish ‘environmental change’

from ‘natural environmental variability’ in order to determine if the root causes of environmental change may be considered attributable to human activity. Natural environmental variability is normally of a periodic nature whereas environmental change can be experienced as a directional trend; either gradual or drastic, but with a high probability of being irreversible.From the above, it follows that both the public and private sectors should rapidly mainstream environmental considerations and trends into their policy making, strategic planning, operations and market positioning. Consequently, the primary audiences for this book are decision makers and advisors at all levels of society, from government to civil society. The purpose is to provide them with a snapshot of pertinent scientific evidence to assist them in formulating intelligent and responsible policies and practices for the betterment of our society and to ensure the long-term futures of South Africans. Yet, the scope, breadth and depth of subject matter covered also renders this text useful reading for teaching and for further studies in related disciplines.

Making sense of environmental complexity

The natural environment is often illustrated as a spider’s web consisting of interconnected strands. Although each strand is fragile on its own, the intricate and beautiful web structure provides it with resilience against external forces. Similarly, global-scale earth systems (i.e. biogeochemical cycles of the atmosphere, oceans and land) can be viewed as nested and multi-scaled ecosystems integrated through interactive processes. These systems are systemically afflicted by natural and human forces that act at multiple scales.

Introduction

�/��F��(��(F��?��=�;Q��8��(��B�Q��*F(;�6 �/�/��F��(�� (�� F��F ?��?? ��=��=��=��=�;�� Q�� 8�8�8 (��(� ��B��B�B�B�B�� Q�Q�QQ �*F�*F�*F�*F(;�(;��(;�66666666

Amidst the obvious complexity of ecosystem studies, a standardised conceptual model of ecosystem function has emerged over time. This model was adopted by the United Nations Commission on Sustainable Development in 1995 and forms the basis of most state of environment reports, including those from South Africa [1]. The model is called the Driver-Pressure-State-Impact-Response (DPSIR) model (See Figure A) and it forms a golden thread that permeates the work presented in this book.

Batho Pele

Batho Pele − ‘People First’ − is the well-known slogan of the South African Government. It is therefore appropriate that the opening section of this book addresses issues of ‘People and Environmental Change’. The subsequent chapters describe a variety of pertinent environmental issues grouped into broad large-scale ecosystem topics spanning the atmosphere to the oceans. The book ends with a concluding chapter.South Africans, across the board, are dependent on these vital life-supporting systems and what is presented should serve as a reality check about the status of these systems. From our understanding of environmental change, people are collectively and rapidly transforming the environment for short-term economic and lifestyle gains, whether by choice or purely in order to survive. Yet, it should be clear that the longer-term impacts of irreversible environmental change will undermine the quality of human livelihoods and may compromise the essential life-support benefits derived from ecosystem services. In most instances, due to disparate access to resources, services, education and infrastructure, it must be anticipated that environmental justice and equality will suffer in the face of environmental change.Environmental change is a global concern and requires ongoing observation, interpretation and responses from South African government and civil society. This book is therefore a bona fide ‘science for society’ contribution.

��8��)7�;��;�9�B�=�*F�?��F�

��8��)7��*�"��!��"�� )��"��$� �� #��%� �9��%� ��%��(��F��$

�#��"�� "�� $� �� "��%� ��%� ��"��%� �� &�� $

�9�� %��%� ��%��'�� %�� "�$��%�� %��"� ��%�� %�� )��"��$

�� "�� $��"��%��"��"��$��%��"��$��"��%�� %�� %��%��%�"��%��%��%��$

�(�� "�� )��"%��%��"� �� $

�F�� %� �"�� %� ��"�� %� ��"�� @��%�� "��"� ��%��"�� "�$

��%�� %��"��"��!%��"��"��$

�/��F��(��(F��?��=�;Q��8��(��B�Q��*F(;�6

(��F�#B;�(�� 7(�(�� F��#F�#B;�B;�B;�B;B;�(��(� 77777777777

*�"�� 8��)7�#9�(F��$��F��B�� 9��"��$�8�� 8��)7�F��%�+,,4!$�B�� 9��"��K��

(��F�#B;�(�� 7

��)��)�� ?��%�/��$��/��

States and Trends in the Aquatic Environment

SECTION 4

FRESHWATER AND ESTUARINE SYSTEMS

MARINE INSHORE ENVIRONMENT

MARINE OFFSHORE ENVIRONMENT

181


Introduction �}`W��$��z^j�^V}X ?x}x_x�?`j}`}`

Change is an integral part of all aquatic environments – not only do they change seasonally, they also fluctuate annually because the amount and distribution of rainfall and river run-off in any one year is never the same as the next. Similarly, the occurrence of floods and droughts is unpredictable and these events have the capacity to alter aquatic ecosystems in a way that persists for years or even decades. However, the changes that influence rivers and estuaries on the scale of centuries and millennia arise primarily from global or climate change. Scientific evidence has shown that the world has gone through periods of major climatic shifts, from ‘snowball earth’ when the entire globe was covered in snow and ice, to periods when tropical conditions prevailed over much of the planet, including Antarctica. What we have been experiencing over the past few centuries is a trend towards the latter conditions, which is being accelerated by massive production of greenhouse gases by vehicles and industries around the world. Based on historical and existing rainfall records, South Africa can be classified as an arid country, with a current mean annual freshwater run-off of approximately 49 000 million cubic meters. This scarcity is compounded by the uneven distribution of water resources, with the western parts of the country receiving less than 40% of the country’s run-off, in contrast to the eastern region that tends to have a higher run-off. The flow regime of South African rivers, which is normally somewhat erratic and linked to rainfall events, has a direct and indirect impact on the state of both freshwater and estuarine plant and animal communities. Aquatic ecosystems are adapted to these naturally variable flow regimes and this has shaped South Africa’s aquatic flora and fauna into various unique radiations, most of which are endemic to the region. However, these ecosystems are often not well adapted to the additional stresses induced by certain human activities, such as pollution,

182

estuarine pollution is invariably taken up by the animals living within these ecosystems, the consequences of which are severe for both the affected organisms and people utilising estuarine resources.Climate change affects both rivers and estuaries, with changing temperature and rainfall patterns being particularly important. Changing river flows and water temperatures can result in new fish and invertebrate distribution patterns, with tropical species expanding their distribution and temperate species reducing their distribution under warming scenarios. Estuaries in particular are vulnerable to climate induced changes that affect the marine environment. For example, a sea-level rise of only 5 cm caused by global warming will lead to changes in estuary shape and size. In addition, altered wave climates around our coast can lead to either increased shoreline erosion or deposition, both of which will influence estuarine connectivity with the marine environment. With the advent of genetics in the management of water resources, scientists have been able to report a correlation between the loss of genetic variability in some freshwater species and the devastation of riverine habitats due to reduced gene flow between populations. Such adverse conditions in river systems are caused by over-abstraction of water, pollution and physical barriers like impoundments, especially when there is no provision of fish ladders. All the above challenges brought about by human activities call for interventions by multidisciplinary teams that have the ability to appreciate the challenges pertaining to South Africa’s aquatic systems and to recommend management actions to reverse the deterioration that is taking place. The authors in this section give specific and holistic perspectives around some of these problems, all of which require attention if we are to ensure that key elements are factored into the solutions that are needed if our rivers and estuaries are to survive global change.

excessive soil erosion, over-abstraction from rivers and inter-basin transfers. In addition, the stresses created by climate change and greenhouse gases produced by anthropogenic activities, such as the burning of fossil fuels, has further exacerbated an already precarious situation. The introduction of alien plant species has also created major problems in our river catchments and the DWA Working for Water Programme is trying desperately to reverse this invasion and restore water delivery to both rivers and estuaries. When one adds the problems created by the introduction of alien aquatic invertebrates and fishes to our streams and rivers, the need for management action becomes overwhelming.Support for the view that we are responsible for negative trends in our rivers is provided by the decrease in freshwater fish population sizes and diversity, as well as changes to other indicator species (for example, invertebrates) of the health of aquatic systems. This trend is not something that has manifested itself in recent decades – indeed, as early as the 1960s it was reported that it was impossible to collect certain fishes from their type localities in the upper reaches of the Crocodile River due to pollution of the water resources. The shading effect of afforestation in some previously grassland catchments has changed the water temperature of the associated rivers to such an extent that fish distribution has been altered. Certain invasive trees, such as black wattle, have choked river catchments and caused perennial systems to become seasonal or intermittent in their flow regimes. When river flooding occurs in valleys infested by alien vegetation, the normal scouring pattern of the river is often altered due to large amounts of tree and other plant debris blocking the river channel. This has important negative consequences for the maintenance of habitat diversity within river and estuarine ecosystems. Estuaries, which are defined by the balance between freshwater inflow on the one hand and seawater influx on the other, are also impacted by altered river flow regimes. Since rivers bring vital nutrient and organic supplies to estuaries, the loss of freshwater inputs on the productivity of estuaries is significant. However, it is not only water quantities that are vital to estuaries – water quality is just as important. Rivers with high sediment loads due to catchment erosion will cause the smothering of submerged plants and the loss of nursery areas for fishes and invertebrates. Similarly, riverine or

��#��F��#��(��Q��B��(;��(F��?��*F��Q��F��#��B�F(��K��?� 183


Estuaries and global change With an emphasis on the ichthyofauna

�^�x}`�;$�w`qVk �W�{k��$�9`jV\kxW

Estuaries are dynamic environments that perform important ecological functions, such as providing nursery areas for numerous species of fish and invertebrates, as well as subsistence and recreational functions. However, estuaries are amongst the most threatened habitats in the country with reduction in freshwater inflow, coastal development and over-exploitation of living resources being the most important factors contributing to their deterioration. Climate change is also predicted to have a large impact on estuaries with the way in which individual estuaries respond to climate change depending to a large extent on other impacts already threatening the estuary.

Introduction

Estuaries are the meeting place of freshwater from rivers and saltwater from the sea which makes them unique environments that are of commercial, subsistence, recreational and ecological importance. There are approximately 250 estuaries (with a total area of 600 km2) along the 3 000 km coastline of South Africa [1]. Conditions in South African estuaries are markedly different from those in the adjacent marine inshore waters. South Africa’s marine inshore waters are typically subject to turbulent wave action; while in contrast, estuaries are calm, sheltered and shallow and provide important nursery areas for many species of marine fish and invertebrates. Numerous species of fish and invertebrates (more than 100) use estuaries as nurseries and/or feeding grounds. Species dependent on estuaries as nursery areas often spawn or breed at sea. Egg and larval development takes place at sea and this is followed by the mass migration of larvae and juveniles into estuaries, where

higher temperatures and a rich food supply favour rapid growth. Juveniles typically remain in estuaries until the onset of maturity and then migrate back to sea [2]. Estuaries also perform other important ecological functions, such as providing conduits for species that migrate between the sea and rivers (such as eels), and many bird species depend on estuaries at different stages of their life cycle. Many coastal communities rely on estuarine resources for subsistence and estuaries are important areas for recreational activities, such as fishing, swimming and tourism. Despite the importance of estuaries they are amongst the most threatened habitats in the country [3].

The impact of human activities on South African estuaries

South African estuaries are subject to a range of man-induced impacts and have often been focal areas for human settlement and resource use. The general perception of estuarine scientists is that the condition of many estuaries has deteriorated significantly over the past 15 years. The three most important factors contributing to the deterioration are: reduction in freshwater inflow, coastal development and over-exploitation of living resources such as fish and bait organisms [4]. Coastal development in the last decade has also led to eutrophication (nutrient enrichment) and sand winning being major threats to South African estuaries.South Africa is a semi-arid country and as a result there is a growing demand for freshwater. This has resulted in the damming of rivers and the use of water for irrigation and industry (Figures 4.1 and 4.2). Invasive alien trees, which use large amounts of water, are also responsible for reducing river flows in South Africa. Water abstraction reduces the amount of freshwater that reaches estuaries, which in turn affects nutrient levels, organic matter content, salinity (saltiness) and turbidity (murkiness) in affected estuaries. Numerous studies in South Africa and elsewhere have shown that reductions in freshwater flow have a negative impact on fish and invertebrate species utilising estuaries. Studies comparing freshwater deprived estuaries with naturally functioning estuaries have shown that the freshwater deprived estuaries often have fewer individuals and species of fish. Reductions in river flow have a negative impact on all estuary types. In South Africa over 70% of the estuaries only open to the sea periodically and are cut off from the sea for

OBSERVATIONS ON ENVIRONMENTAL CHANGE IN SOUTH AFRICA184

varying periods by sandbars that form at their mouths. Reduced river inflow into these estuaries leads to prolonged closure and shorter open phases which inhibits the passage of fish between estuaries and the sea leading to a reduction in species richness. If upstream water abstraction continues unchecked it will result in a decrease in species richness, to the detriment of important fishery species that are already overexploited.Besides the effects of water abstraction in catchments estuaries also face direct pressures on the estuarine environment [5]. Coastal development, mainly in the form of residential and recreational development (urban encroachment), often focuses on estuaries [6]. Recreational development is known to have a major impact on birds and fish in estuaries [5]. Furthermore, development brings with it associated infrastructure, such as marinas, jetties, roads and railways [5, 6]. Development in and around estuaries also has a significant impact on coastal wetlands, such as mangroves and saltmarshes that are found in estuaries. Mangroves are amongst the most threatened ecosystems in the world with more than half their original area already lost [7]. In KwaZulu-Natal mangroves have been removed from the Sipingo, Mgeni and Mkomazi estuaries and in Durban Bay approximately 200 ha of mangroves have been destroyed. Mangroves have been replaced by industrial, residential, agricultural and harbour development [8]. Poor urban planning has also led to the need to artificially breach many estuary mouths to lower water levels and prevent the flooding of houses [5]. Artificial breaching of an estuary mouth when the water is below the level at which breaching occurs naturally reduces the amount of scouring (sand flushed out of the estuary when it opens) and results in an accumulation of sediments in the estuary mouth in the long-term. The effect of artificial breaching on plants and animals can also be severe.Pollution pressure on estuaries is also increasing, particularly in KwaZulu-Natal. The greatest pollution pressure occurs as a result of industrial effluents, pesticides from agriculture and sewage (Figure 4.3). The most degraded estuaries are found north and south of Durban. Soil erosion is also a major threat to estuaries, particularly estuaries in KwaZulu-Natal and those in the former Ciskei and Transkei regions of the Eastern Cape [5]. Soil erosion results from overgrazing, poor farming techniques, the destruction of wetlands in

*�"��7$-� #��F��%��;��$��#��(�/�

Figure 7$+� ��F��%��;��$��#��(�/�

��#��F��#��(��Q��B��(;��(F��?��*F��Q��F��#��B�F(��K��?� 185

catchments and the removal of river and streambank vegetation [5]. Increased sediment loads flowing into estuaries results in changes in the community of animals living in the sediment (such as crabs and worms) and cause estuaries to become shallower, which in turn affects the temperature and turbidity of the water column. Shallow water also favours the encroachment of reeds which will further reduce the surface area of the estuary [5].

Figure 7$6� (�� @�� >�� ;�� F��/��%��O��)��$

The utilisation of estuarine fish resources plays a major role in the local economy and food supply in many parts of South Africa. However, many species in estuaries are vulnerable to over-exploitation. These include many species of fish that are already over-exploited and bait organisms (Figure 4.4).

Figure 7$7� Q�� "� �� Callianassa kraussi!� �� "�� %��;��!$

Climate change is also predicted to have a large impact on estuaries. The way in which individual estuaries (and the biological community) respond to climate change depends on other impacts already affecting that estuary. Of all climate induced changes, sea-level rise is seen as the greatest threat to mangrove and salt marsh ecosystems in estuaries [9, 10]. Several climate models project an accelerated rate of sea-level rise over the coming decades (for example, [11]) and as coastal wetlands are situated in the transition between the land and sea they are particularly vulnerable to sea-level rise. Global surface temperatures have increased by 0,74 ºC between 1906 and 2005 [11]. The most obvious changes associated with increased sea surface temperatures around South Africa will be shifts in the distribution and abundance of individual species or species assemblages. Because the distribution of species is often determined by their tolerance to climatic extremes, ecologists predict that species will respond to climate change by shifting their distribution towards the poles. However, temperature is only one of many interacting climatic variables that may drive ecological change in marine systems [12]. Although distribution shifts are expected in South African waters, they have not been modelled as yet. This is because anticipated shifts are closely associated with ocean currents and changes in the movements of currents have not been accurately predicted [3].General atmospheric circulation models, although less conclusive than predictions of air temperature in South Africa, indicate the likelihood of a decrease in rainfall along the west coast of South Africa, and to a lesser extent along the south coast and a slight increase in rainfall along the east coast [3]. Rainfall events are also predicted to get more intense. Reductions in the amount of freshwater entering estuaries in South Africa would lead to an increase in the frequency and duration of estuary mouth closure with all the associated problems highlighted above. Reductions in the amount of freshwater entering estuaries will also affect the extent to which pollutants are diluted before they reach estuaries, thereby increasing the concentration of pollutants in estuaries.Since pre-industrial times the atmospheric concentration of CO2 has risen by 35% (measured in 2005) [11]. Elevated atmospheric CO2 concentrations may increase productivity of some estuarine plant species but the effect of


enhanced CO2 on estuarine plants is poorly understood [10]. The frequency of extreme high water events and high intensity storms is predicted to increase over coming decades (with these events already recorded in 2007 and 2008). These events cause habitat destruction, although the extent to which estuaries are affected is dependent on human alterations to these estuaries (Figures 4.5 and 4.6).

Figure 7$�� Q�"��%��;�� +,,5!$��#��9��;��(�/�

Figure 7$�� Q�"��*��F��%��;�� +,,5!$��#��9��;��(�/�

Managing estuaries

In the short time frame of a few decades the negative consequences of climate change can be avoided or minimised through the management of current stressors of estuaries. Estuary management is concerned with the maintenance of the physical and biological processes that make estuaries the unique and important environments that they are. For example, protecting estuaries from excessive freshwater abstraction may provide some protection against decreased rainfall. The National Water Act (No. 36 of 1998) requires a certain minimum amount of water be left in the estuary for ecological purposes. Management classes must also be determined for each estuary. This management class is based on the present condition of the system and provides the baseline for comparisons within and between estuaries [4]. Estuaries also often face threats that originate outside the estuary and management should incorporate wider management strategies including the whole catchment and coastal zone [13].

��#��F��#��(��Q��B��(;��(F��?��*F��Q��F��#��B�F(��K��?� 187


Estuarine fish communities in hot water?

�^�x}`�;$�w`qVk �}`W��$��z^j�^V}X

9`{}�#$�;x|}Vf

Increasing sea temperatures may have a range of implications for coastal fish species. The most obvious will be shifts in the distribution and abundance of individual species or species assemblages. The fishes of the warm-temperate East Kleinemonde Estuary have been sampled since 1995. Indicative of a warming trend, six new species of tropical fishes were recorded in the catches from 1999 onwards. Mean annual sea surface temperatures recorded along the adjacent coast have also increased and may have facilitated the southward extension of tropical marine fishes into the warm-temperate biogeographic zone. Similarly, the diversity and dominance of tropical species in the Mngazana Estuary have increased when compared with a similar study conducted 25 years earlier.

Introduction

Our rivers, estuaries and the sea are heating up. Over the past forty years sea surface temperatures off Port Elizabeth have increased by about 0,25 ºC per decade [1]. Although this change may seem insignificant, fish are a lot more sensitive to temperatures than are terrestrial animals. This is because fish cannot maintain a constant body temperature and in most cases their body temperature is the same as the water around them. All species of fish have an optimal temperature range and cannot survive in temperatures too far out of this range [2]. Therefore, the most likely changes associated with global warming will be shifts in the distributional ranges of species and changes in the composition of species assemblages [3].

Characteristics of South African estuaries

Estuaries are shallow and strongly influenced by wind, wave action, rainfall, water and air temperatures; consequently, climate change may have an even greater impact on these systems than the surrounding land and sea. The estuaries along the coast of South Africa, and their associated fish communities, can be grouped according to biological, physical and geographical criteria [4] with the coast of South Africa having three distinct biogeographic zones: a subtropical zone, a warm-temperate zone and a cool-temperate zone (Figure 4.7). Few fish species occur in all southern African estuaries and many fish species only occur within specific biogeographic zones. Harrison [5] recorded differences in estuarine fish communities around the South African coastline, with a gradual decrease in the number of species recorded in estuaries form east to west, mainly as a result of the decreasing number of tropical marine species recorded. Cool- and warm-temperate estuaries are mainly dominated by species that only occur in southern Africa and not by tropical species.

*�"��7$4� ?�� "��"��"��%��'�� %��"�� $��!


The East Kleinemonde estuary

As part of an ongoing long-term study, the changing fish assemblages in the East Kleinemonde Estuary (Figure 4.7) have been studied since December 1995. This small (3 km in length) temporarily open/closed estuary situated on the warm-temperate southeast coast of South Africa is closed off from the sea for most of the year by a sandbar that forms across the mouth and usually only opens after river flooding in the catchment. A total of 38 species of fish were recorded in the East Kleinemonde Estuary between December 1995 and July 2006 [6]. During the earlier years only temperate species were recorded. However, indicative of warming waters, six new tropical species, namely, longarm mullet, robust mullet, diamond mullet, largescale mullet, tank goby and thornfish, have been recorded in the catches from 1999 (Figure 4.8).

*�"��7$5� ��'��$��4%�-6��-7��F�� (�� /��%� 8�� Q�� "�� %��"��'��#��%��"��!��

The four tropical mullet species (longarm mullet, robust mullet, diamond mullet and largescale mullet) and thornfish normally occur in the tropical and subtropical estuaries of southern and eastern Africa (common in the subtropical estuaries along the KwaZulu-Natal coast), with the occasional straggler being recorded in some warm-temperate estuaries [8]. The tank goby is a tropical and subtropical species that has only previously been recorded as far south as the Mngazana Estuary on the east coast (Figure 4.7). Of the six species, longarm mullet and largescale mullet were recorded almost every year after 2002 and were found in both the summer and winter samples. This means that they were not just stragglers straying into the estuary with the warm current but rather that water temperatures were continually within the tolerance range of these species. Due to the increased occurrence of tropical species, the total number of species recorded in the East Kleinemonde estuary between 1996 and 2006 has increased steadily (Figure 4.9) [6].

Changes in fish species distributions in Eastern Cape estuaries

Mean annual sea surface temperatures recorded along the adjacent coast at Port Alfred (15 km south of the estuary) have increased at a rate of 0,09 ºC per year over the past decade and may have facilitated the southward extension of tropical marine fishes into warm-temperate Eastern Cape estuaries (Figure 4.9). There has also been a general positive trend in South African air temperatures for the period 1960 to 2003 [9] and East London, which is situated approximately 100 km north east of the estuary, has shown a significantly positive trend in annual average and annual average maximum and minimum air temperatures [9]. Increasing air temperatures may have a greater impact on temporarily open/closed estuaries than on permanently open estuaries, as these shallow systems are cut off from the effect of sea temperatures for long periods and therefore respond to a greater degree to prevailing land, air and river water temperatures [6].

��#��F��#��(��Q��B��(;��(F��?��*F��Q��F��#��B�F(��K��?� 189

*�"��7$3� ��'��«;!��9��-33��+,,�$��!

The effects of climate change on fish distributions have also been recorded further north in the Mngazana Estuary (Figure 4.7). In two similar studies of the fish community of the Mngazana Estuary separated by 25 years [10, 11] the proportion of tropical species recorded in catches in winter increased from 60% in 1975 to 74% in 2001 (Figure 4.10). In contrast, the percentage of temperate species recorded in catches decreased from 28% in 1975 to 24% in 2001. Previously tropical species extended their ranges southwards into this estuary during summer as the temperatures warmed up, while temperate species extended their ranges northwards into the estuary during winter as temperatures cooled down and became favorable for them [10]. The increase in the overall percentage of tropical species recorded during winter, from 1975 to 2001, may be an effect of global warming. Higher average winter temperatures would allow more tropical species to use the estuary during winter, while limiting the northward penetration of certain temperate species [11].

*�"��7$-,� ��'�� ?�"�>��$��-,%�--�!

Conclusion

Both the Kleinemonde and Mngazana studies have highlighted the increased occurrence of tropical fish species in estuaries along the east coast of South Africa. Although changes in the abundance of fish species have not been reported in these two estuaries, climate change may eventually result in marked changes in the composition of coastal fish communities. It is important to keep in mind that each species responds differently to warming, and communities do not shift their distribution as a unit. Climate warming is therefore likely to create new mixes of foundation species, predators, prey and competitors, which makes it very difficult to predict how communities will respond to climate change [12].



Changing patterns of freshwater fish diversity

in South Africa9`{}�Q$��_V}jxW� �^}}Vq�;xVj�V\

The distributions of South African freshwater fishes have changed substantially over the last 100 years. We can estimate past distribution ranges using historical records from museums. The most significant changes to the environment of freshwater fishes in South Africa are caused by man-made structures including large dams and inter-basin transfer schemes, the abstraction of large volumes of water from rivers, the degradation of water quality through pollution and the introduction of, and invasion by, alien competitors and predators. The conservation statuses of rivers reflect these changes. The impacts of these changes on fish distributions are illustrated by focusing on selected indigenous freshwater fish species. The distributions of many species have contracted while some have expanded. Introduced aliens are important drivers of change in indigenous freshwater fish distribution patterns.

Introduction

Freshwater ecosystems in South Africa have changed substantially in the last few decades [1]. These changes are especially evident in the construction of major and lesser impoundments, the increased abstraction of water for agriculture, urban growth, industry and mining, downstream pollution and the rampant invasion of alien vegetation.While it is not surprising that fish distribution patterns have changed, the nature and extent of these changes need to be documented. We present a perspective from long-term records of freshwater fishes in museum collections and the literature. In doing so we direct the focus to the irreplaceable value

such collections have for science and human well-being in a changing and challenging world.

Natural distribution patterns

We can estimate the natural distribution ranges of most indigenous freshwater fish species by referring to the collection records available in museums. The Atlas of Southern African Freshwater Fishes produced by Scott et al. [2] provides maps based on such records drawn from the major collections, worldwide, of southern African freshwater fishes.An effective summary of the emergent patterns was presented by Skelton [3] and more recently by Tweddle et al. [4]. Two broad ecological faunas occur in South Africa: a tropical-subtropical fauna with southern limits described by the Orange River system in the west and the attenuated coastal plain to around the Umtamvuna basin on the east coast, and a temperate fauna with its northern limits determined by the boundaries of the interior highveld plateau and the escarpment from KwaZulu-Natal through Mpumalanga and Limpopo Province. Within this framework, fish distribution patterns are generally described by a set of more restricted aquatic ecoregions in southern Africa as illustrated by Skelton [5] and Thieme et al. [6] (Figure 4.11).

*�"��7$--� �� "�� %� �� et al.� ��$� �� "��"��$

��#��F��#��(��Q��B��(;��(F��?��*F��Q��F��#��B�F(��K��?� 191

Topography and climate are important determinants of species distribution ranges. The configuration and evolution of drainage basins, in particular, have determined the distribution ranges of South African freshwater fishes. Thus, a species may be restricted to a single catchment or a few catchments, but depending on the size of the drainage system, may be considered widespread or narrowly distributed. Most fishes endemic or indigenous to the large Orange River system, for example, are considered widespread species [7]. High topographical diversity tends to create smaller, more fragmented drainages with more numerous natural barriers separating populations and species. Hotspots of fish diversity therefore occur in the Cape Fold Mountains and along the escarpment drainages, especially in Mpumalanga Province [4] (Figure 4.11).Mountain catchments are mostly removed from human interference and frequently provide refugia. However, the advantage of isolation can be easily off-set when alien predator species are introduced directly and extensively for recreational fishing purposes in remote mountain streams. This is evident, for example, in the Drakensberg-Maloti highlands and the streams of the Olifants River system in Western Cape Province.

Contracting ranges

Current evidence indicates that the distribution ranges of most South African freshwater fishes are contracting. Examples are evident from both widespread species (for example, the southern barred minnow, Opsaridium peringueyi) (Figure 4.12) [4, 8] and more restricted species (for example, the Maloti minnow, Pseudobarbus quathlambae) (Figure 4.13) [9].In certain severe cases of range contraction, action has been taken to conserve a species by translocating populations to new areas. An example of this is the Maloti minnow, which was probably widespread across the tributaries of the Orange River in Lesotho, but now only survives in a few protected stream stretches, including at least three sanctuary streams above natural barriers where aliens are absent [10]. Genetic research has, however, shown that there are actually two Pseudobarbus species in Lesotho, which means that each species is considerably more restricted and threatened than is the undivided taxon [11].

*�"��7$-+� �� "�� "��Opsaridium peringueyi ��. /��"��+��"��%��%��+��!$��"��-35�$� F��+,,�)+,,3!$

*�"��7$-6� #�� "�� Pseudobarbus quathlambae sensu lato �� =��$��"�� )+,,,� �� $� �� %� �� "��+�,,,��$��"��"�� $�F�� $��-,�


The now severely fragmented distributions of every indigenous species in the Clanwilliam Olifants River system (for example, [4, 12]) reflects the declining status of indigenous fish populations in almost every drainage system across the Cape Fold Mountains, mostly due to water abstraction and alien predators. Marr et al. [13] illustrated the severely contracted distribution and population numbers of the Twee River redfin (Barbus erubescens) (Figure 4.14) and an undescribed Galaxias species in the Twee River catchment of the Olifants River system in the Cederberg mountains.

*�"��7$-7� �� "�� "��Barbus erubescens��F��%� ;�� F�� %� �� ;��%� �� ?��et al. �-6�. /��"�� "��circa�-347$��%��'��-334:+,,4��$

Expanding ranges

In contrast to the general trend of contracting distribution ranges, a minority of indigenous species have recently dramatically expanded their ranges in South Africa through human introduction and interbasin transfer

systems. These include the Mozambique tilapia (Oreochromis mossambicus) (Figure 4.15a), the banded tilapia (Tilapia sparrmanii) (Figure 4.15b) and the Vaal-Orange smallmouth yellowfish (Labeobarbus aeneus) (Figure 4.15c) [5, 14-16]. Other examples include the sharptooth catfish (Clarias gariepinus), now widely distributed in the coastal rivers of the Eastern Cape and the Western Cape [17], and two species, the Cape kurper (Sandelia capensis) and the Clanwilliam yellowfish (Labeobarbus capensis), introduced into the Twee River catchment [12, 13, 18, 19].In addition to the indigenous species that have recently expanded their distribution ranges, a number of alien invasive species have become well established [14, 15]. The introduction of alien species has occurred with varied degrees of human intervention and over different time scales. In some cases (for example, trout and bass) (Figure 4.15d and e) the history of introduction and subsequent establishment of the species is well documented and understood, but in others, for example, carp (Figure 4.15f ) and various cichlid species, the histories of introduction are less well documented. In general it seems that invasion proceeds rapidly to its potential range, especially when the invaded system is environmentally compromised.These invasions have fundamentally and irreversibly changed practically all South African freshwater fish communities. Natural freshwater fish communities are now scarce and usually restricted to short, isolated river reaches in remote mountain catchment areas.

Conclusions

Freshwater ecosystems are among the most threatened environments on the planet [20]. The changing distribution patterns of freshwater fishes are visible responses to the widespread and rapid deterioration of freshwater ecosystems. Most indigenous species are experiencing range contraction, and alien and translocated indigenous species are expanding their ranges. Both these outcomes are negative consequences from a conservation perspective. We are realising that our understanding of aquatic biodiversity is far from adequate at the organism, species and community levels, and this affects sound conservation judgements. There is thus a growing demand for more accurate and precise biodiversity information that originates from well-managed and documented natural history collections.

��#��F��#��(��Q��B��(;��(F��?��*F��Q��F��#��B�F(��K��?� 193

��!

��!

��!

�!

��!

��!

*�"��7$-�� "�� "��"��'��$��!�Oreochromis mossambicus.��!�Tilapia sparrmanii$��!�Labeobarbus aeneus ��'��$��!�F��$��!�=��"��%��&��$��!�;��$�8�� "��"�$


The impacts of afforestation on surface water resources

#`�^X�=V�?`^j\V #`�V��xjj

#^\_��V\k�V}X

South Africa is a dry country and has limited supplies of water with which to meet the demand for human, agricultural and industrial use. Research has clearly shown that plantations use about 50% more water than the natural vegetation they replace, or about 3,2% of mean annual run-off. On the other hand, South Africa needs the wood, paper and other products produced by the industry. Special legal provisions are in place to ensure that plantations do not take more than their fair share of the available water whilst continuing to meet the needs for their products.

Why have plantations?

South Africa is a dry country with an average annual rainfall of less than 500 mm (about half the world’s average) and is facing growing water shortages as demand increases. Commercial plantations using introduced tree species are known to use large quantities of water, yet the country still seeks additional land for afforestation. The reasons for this are better understood if we go back into history and also explore how forest products currently meet a wide range of needs and generate income for the country. About 0,7% of South Africa naturally supports indigenous forest, so there has always been a shortage of wood for construction, mining, paper and various other products. By the late 1800s, the forestry department recognised that the need for wood could only be met either by importing wood or by establishing forest plantations using pines, eucalypts and wattles [1]. The first plantations were established in 1884 at Tokai near Cape Town, but expansion was initially slow. Timber shortages during World War I and again during World War II launched a


drive to achieve self-sufficiency in wood products. This led to a dramatic expansion in the area of plantations and by 1955 about 560 000 ha had been afforested by both the state and private sector [2]. The expansion of the wattle growing industry was driven largely by the vibrant market for tannins extracted from the bark. By 1955, wattles comprised about half the total area and were planted mainly in KwaZulu-Natal and the Eastern and Western Cape Provinces [2].In 2007, the total plantation area was about 1,34 million hectares, with about 53% being pine, 38% eucalypt and 8% wattle (Figure 4.16) [3]. About 45% of the plantations are in Mpumalanga and Limpopo, 39% in KwaZulu-Natal with the rest in the Western and Eastern Cape (Figure 4.17). About 35% is planted for solid wood production and 55% for paper and fibre products. These products meet most or all of the country’s needs for solid wood and processed wood products. Timber sales from plantations generated R5,2 billion, sales of timber products generated R18,5 billion, and exports were R12,2 billion [3]. In 2007, the industry provided about 77 000 jobs and indirectly supported an estimated 462 000 jobs. Given typical employee to dependent ratios, this means that the timber industry supports about 1,7 million people, a large proportion of who live in rural areas.

What are the impacts of plantations on water resources?

Plantations replace relatively short natural vegetation (for example, grasslands and fynbos shrublands) with deep-rooted, tall trees. In the case of grasslands they also replace seasonally dormant with evergreen vegetation. Productive commercial plantations need at least 800 mm of rain so they are located mainly in the high rainfall and high water yielding catchment areas, particularly along the escarpment areas of the Eastern Cape, KwaZulu-Natal and Mpumalanga (Figures 4.17 and 4.18). The overall water-use of the plantation areas in South Africa was estimated to be 1 417 Mm3, which is about 3,2% of the mean annual run-off and approximately 101 Mm3 (7,8%) of the dry season flows [6].

*�"��7$-�� $��$��$��#��6�!

*�"��7$-4� �� =;!�� ?��F��7��!$��=��7��!

��#��F��#��(��Q��B��(;��(F��?��*F��Q��F��#��B�F(��K��?� 195

*�"��7$-5� 9�� #��"��?��"�$��#$/$��

*�"��7$-3� (�� ?��F��)��7��!��$�� $��#��!

Plantation forests are generally responsible for an annual streamflow reduction of between 50 and 150 mm depending on climate and the vegetation replaced, with an average of 70 mm. This is the equivalent of 700 m3 of water per hectare per year. By comparison, irrigation rates are usually between 5 000 m3 and 10 000 m3/ha/year. In individual catchments plantations can dry up streams completely, and the drier catchments lose the highest proportions of their flow. On the other hand, the more humid catchments (those in the more productive mountain catchment areas) suffer the largest absolute reductions in flow. The effects on streamflow may be measurable within three years of planting, depending on how quickly the trees dominate the site, and the reductions in streamflow tend to follow the growth rate of the plantation. This leads to earlier and larger flow reductions under eucalypt trees than under pines of the same age [7]. In cases where the entire catchment has been planted it has taken several years for the run-off to recover to the pre-planting conditions after clearfelling [8]. Impacts on water quality are low, provided roads and intensive activities like felling are managed properly. Many of the plantation species are aggressive invaders (for example, Black wattle [Acacia mearnsii] and pines [Pinus species]) and have invaded large areas of natural vegetation [9]. The impacts of dense invasions on streamflows are comparable with those from plantations [9]. The Working for Water Programme is tackling these invasions but it will take decades to clear invasions by these and other species.

Are there other impacts?

A little known consequence of afforestation is the effect upon the soils. After many years of plantation cover a substantial litter layer can build up. The decomposition of this crude material, which is high in tannins and polyphenols, can lead to a drop in pH of the soils. This higher acidity can make low fertility soils even poorer. Another risk to the soil is that of wildfire. When a severe wildfire burns off the ground material and heats the soils under dry conditions, the soils beneath plantations may become water repellent. While this condition is reversed within a few years, the burned site is vulnerable to accelerated soil erosion in the interim [10].


How did the government and industry respond to clear evidence that plantations use more water than the vegetation they replace?

In the 1930s there was heated debate about whether tree planting resulted in more water in rivers or not, but growing complaints about forest plantations drying up streams and rivers forced the government to act [11]. A research programme was launched to investigate this problem and the first studies were initiated in Jonkershoek in the Western Cape in 1934 (Figure 4.20) [12]. This study was later complemented by the establishment of others at Cathedral Peak in the KwaZulu-Natal Drakensberg, in Mpumalanga, and in Limpopo Province. This research showed clearly that plantations reduce annual and dry season river flows compared with the natural vegetation. The government responded in two ways: firstly, by introducing laws and control systems that address the site level impacts, and most recently by assessing the national landscape to identify areas suitable for tree growing where this would have the least environmental impact and provide greatest economic and social benefits.

*�"��7$+,� ��w�� "�'��+,,3$��#$;$�=��?��

Regulation of forestry development began in 1972 with the introduction of a permit system to manage the establishment of new plantation areas [13, 14]. When this system was introduced, certain catchments were immediately excluded from further plantation expansion because the pre-determined flow reduction limit had been reached. In others, up to 10% more afforestation could be allowed, and in the remainder no limits were set. A flow reduction calculation system was introduced in the early 1990s, allowing forestry officials to assess more accurately whether there was sufficient water available to allow new plantations to be established. In 2002, this was replaced by a set of tables and computation spreadsheet providing total and low flow impact estimates for all quaternary catchments in the country [15].The National Water Act introduced the concept of ‘Stream Flow Reduction Activities’ (SFRA), allowing for the regulation of any non-irrigated land use which results in a significant river flow reduction [16]. Forestry is currently the only declared SFRA. New plantations now require a water use licence and the licensing procedure requires an assessment of the impacts on water resources, agriculture and the environment. The industry has also introduced guidelines for planting, with environmental certification requiring plantation owners to maintain unplanted buffers of 50-100 m along streams and around wetlands, thus reducing plantation impacts on river flows and water quality [17]. They also require the companies to remove invading plant species. These standards generally ensure that plantations have a lower environmental impact than agriculture, particularly when compared with irrigated farming.Recently, the Department of Water Affairs and Forestry has used Strategic Environmental Assessments (SEAs) to identifying new areas for plantations. This includes an assessment of the growing conditions for trees, environmental considerations such as the impact of vegetation transformation on biodiversity, water availability, socio-economic impacts, and a consideration of alternative land uses such as agriculture [18]. SEAs with a focus on forestry and water have been completed in the Mhlathuze Catchment, the Usutu-Mhlathuze Water Management Area and in the Eastern Cape centred on the Mzimvubu catchment [19, 20]. The real benefit of these studies has been in developing approaches to the use and value of water and how the benefits could affect society, the environment and the economy. The Department of Water Affairs

��#��F��#��(��Q��B��(;��(F��?��*F��Q��F��#��B�F(��K��?� 197

and Forestry is currently undertaking a series of studies to assess the potential for additional afforestation in all provinces in the country. Although these studies are not SEAs, they are being addressed from environmental, social and economic perspectives.

What about the future?

Climate change has significant implications for the industry, particularly in the Western Cape where a reduction in rainfall is expected, aggravated by an increase in air temperature and, thus, evaporation. In the eastern parts of the country the increases in rainfall and temperature are likely to balance each other, although rainfall is expected to be even more variable [21]. The impacts of changes in CO2 concentrations are less certain because they are controlled by a variety of factors, but they could reduce plantation water-use. Most of the long-term catchment scale studies of the hydrological impacts of plantations have been terminated. This is very unfortunate given that these studies are needed to provide information on the impacts of climate change that can also be used to develop the models to estimate the hydrological impacts and make properly informed decisions about the future of forestry in this country. These studies also can provide baseline information on how the water use of natural vegetation is changing and its implications for water resource availability in the future.There is no doubt that commercial plantation forestry in South Africa has an impact on water resources but this should be seen in the context of the substantial socio-economic benefits of commercial forestry. A Forestry Industry study estimates that South Africa needs a further 786 000 ha of plantations if it is to meet demand over the next 30 years [22]. However, it is generally recognised that this cannot be achieved given the water resource situation and the intense competition for both water and available land, making 200 000 ha a reasonable target. The SEA in the Eastern Cape found that at least 100 000 ha of additional afforestation would provide a beneficial land use mix in that province. Assessments so far undertaken in KwaZulu-Natal suggest another 40 000 ha, but there is no further expansion opportunity in either Limpopo or Mpumalanga unless water is traded directly out of agriculture to allow for forestry [23, 24].


The South African River Health Programme

F`qx�`}V�;$��V_|V}V

In 1994, the then Department of Water Affairs and Forestry (DWAF), now Department of Water Affairs (DWA), initiated the National Aquatic Ecosystem Health Monitoring Programme in co-operation with the Department of Environmental Affairs and the Water Research Commission. The programme was a response to the need for better information for managing the ecological state of aquatic ecosystems. DWA, the national custodian of the country’s freshwater resources, was the lead agent for the programme. The primary focus of the programme is to collect river health data and make it available, especially in the form of reports on the ecological state of inland aquatic ecosystems and trends. The programme initially focused on rivers and commonly became known as the River Health Programme (RHP). Design and implementation of the programme followed a phased approach of design, development and implementation. The RHP uses several driver and response methods to assess resource ecological integrity, and most of the methods are still being refined. A formal implementation procedure is in place, covering issues such as information storage, reporting and programme co-ordination. The programme has become so successful that it is now operational in many parts of South Africa, with other Southern African Development Community member states adopting the same approach.

Introduction

The then Department of Water Affairs and Forestry (DWAF), now Department of Water Affairs (DWA), initiated the National Aquatic Ecosystem Health Monitoring Programme (NAEHMP) in 1994 in response to the need for information regarding the ecological state of aquatic ecosystems. The programme was previously known as the National Aquatic Ecosystem Bio-monitoring Programme (NAEBP). The ecological state is


based on the biological condition of these resources. The primary focus of the programme is the state of health of aquatic ecosystems, which include rivers, wetlands, estuaries and aquifer dependent ecosystems [1]. The programme initially focused on rivers in a sub-programme known as the River Health Programme (RHP) hence became commonly known as the RHP. The RHP is a component of the NAEHMP with specific focus on river health assessments and reporting on the state of rivers. The programme is administered by DWA under the Chief Directorate: Water Resource Information Management (CD: WRIM), Directorate: Resource Quality Services (D: RQS). DWA, because of its leading role in the RHP, has some unique governance elements that are critical to the success of the programme. These relate to political endorsement and accountability, technical leadership and communication, and capacity and skills. The programme was designed before the National Water Act (No. 36 of 1998) was enacted and it was initiated jointly by DWA, the Department of Environmental Affairs and Tourism (DEAT) and the Water Research Commission (WRC). The programme was initiated to serve as a source of information regarding the ecological state of river ecosystems in South Africa, in order to support the national water resource management.A phased approach was followed for the development of the RHP. In the first few years the emphasis was mainly on research and development of basic monitoring protocols. After that, the programme was pilot tested and became operational in most of the provinces.There are 639 RHP monitoring national sites strategically selected across the country specifically to assess and report on the national ecological health status and trends regarding the aquatic ecosystem health. Both national RHP and regional/provincial RHP complement each other by sharing information collected for the management of the resource and capacity building.

Goals and objectives

The goal of the RHP is to assess and report on the national ecological health status and trends regarding aquatic ecosystems. The information generated is provided to regional water resource managers for management intervention as per recommendations.

The objectives of the RHP are to: � measure, assess and report on the ecological state of aquatic ecosystems; � detect and report on spatial and temporal trends in the ecological state of

aquatic ecosystems; � identify and report on emerging problems regarding aquatic ecosystems;

and � ensure that all reports provide scientifically and managerially relevant

information for national aquatic ecosystem management.The national RHP was not designed to identify the cause of pollution, nor whether the water is fit for drinking purposes or not. Compliance regional water quality programmes are responsible for establishing the cause of pollution and law enforcement through licensing. Regional/provincial RHP has more monitoring sites and detailed data collection, compared to national programmes, to deal with localised problems, such as discharges from industries and mines, and other sources of pollution.

Programme progress

The National Water Act (No. 36 of 1998) came into effect four years after the initiation of the RHP. The Act acknowledges the importance of protecting aquatic ecosystems in maintaining the full suite of goods and services that people rely on for their livelihoods, and requires that a national aquatic ecosystem health monitoring system be established. The RHP was reviewed through the National Coverage Phase in order to align it with the requirements of Chapter 14 of the Act. From initiation until all NAEHMP inception phase products were approved in January 2009, implementation of the RHP has largely been through goodwill by Provincial Task Teams (PTT). These teams consisted of amongst others, DWA Regional Offices, provincial departments of the environment, conservation agencies, universities, consultants and municipalities. While the design, development, and standardisation (concepts, methods, processes) of the RHP is co-ordinated at a national level, implementation activities largely take place at the provincial level. This model of implementation has to date relied strongly on voluntary participation, informal arrangements and a fair amount of flexibility that

��#��F��#��(��Q��B��(;��(F��?��*F��Q��F��#��B�F(��K��?� 199

caters for the diversity of resource realities (both human and financial) across the country. This made the RHP very vulnerable and can affect its long-term sustainability. It was for this reason that DWAF moved into the National Coverage Phase project. The main purpose of this phase was to formalise the RHP, to establish the RHP as a national programme and to align the design of the RHP with the requirements of the National Water Act.The main components of this phase included: � reviewing and revising the current design of the programme to ensure

that it is aligned with DWA’s Strategic Framework for National Water Resource Quality Monitoring Programmes and the National Water Act (No. 36 of 1998);

� determining the programme’s operational requirements; � refining the Rivers Database; � further developing and establishing of quality assurance procedures; � revising the Bio-monitoring short course; and � conducting ongoing research and development (R&D), for example, the

development of a wetlands and estuarine habitat integrity index, ground water dependent systems, fish reference conditions, vegetation response assessment index and eco-status reporting format.

A number of smaller projects, co-funded by the WRC, are implemented and aim to develop a wetlands health index and to further develop, refine and test biological and secondary indices that can form part of the suite of RHP indices.

Responses and drivers measured

A multitude of factors determine the health of a river ecosystem: its geomorphological characteristics, hydrological and hydraulic regimes, chemical and physical water quality, and the nature of in-stream and riparian habitats. It is impractical to monitor each of these factors in detail, therefore the RHP focuses on selected ecological indicators that are representative of the larger ecosystem and are practical to measure. Since resident aquatic communities reflect the effects of chemical and physical impacts in a

time-integrated manner, they are regarded as good indicators of overall ecological integrity. For the purpose of disseminating results of the RHP, the information resulting from monitoring aquatic community components should be simplified to a point where it can be of use to resource managers, conservationists and the general public. This can be done with a biological index that integrates and summarises biological data within a particular indicator group. The resident aquatic communities measured include fish communities, riparian vegetation, diatoms, aquatic invertebrate fauna and habitat integrity, also known as responses, to assess the condition or health of river systems and on Eco-Classification/Eco-Status processes. Appropriate indicators, for example selected fish community attributes, need to be tested and justified and linked to measuring units (metrics) that can be used to index ecological condition. In this context, biological indices are used to quantify the condition or health of aquatic ecosystems and the output format is usually numeric.While biological indicators and indices are the main focus of the RHP, the development and inclusion of indices of physico-chemical, geomorphology and hydrology indicators − referred to as drivers − are also used to increase the information value of the programme and on Eco-Classification/Eco-Status processes.

Data management and storage

The refinement of the Rivers Database project, which was part of the National Coverage Phase, was completed and Version 3 of the database has gone live. This is an interactive web-based database which enables RHP practitioners to capture RHP data on their individual computers and to transfer these data to the national database. The database facilitates capturing and safe storage of the NAEHMP river health data. System access is controlled through compulsory user registration and new users need to register before being able to access either the Rivers Server (website) or Rivers Client (desktop). The Rivers Database consists of three primary components (Figure 4.21). � Rivers Server (web application running on the Internet which is the

centralised repository of data at a national level);


The RHP is an information-orientated programme generating large volumes of information to be analysed and interpreted for dissemination to a wide variety of information users. The efficient and effective storage of RHP information is therefore critical to the programme’s success.

Co-operative governance

The very nature of the NAEHMP: RHP requires the combination of a highly diverse and specialised cluster of skills which cuts across the mandates of a number of sectors and spheres of government [3]. It is therefore impossible for DWA to implement the programme in all its facets on its own.However, the effectiveness of ongoing development and the sustainability of the RHP will be determined by the way that it is governed. In the RHP context, governance is the process whereby individuals and institutions, public and private, manage their common concerns.The main concern is the implementation and maintenance of a monitoring programme with a design based on sound scientific principles and operationally feasible protocols as a means to inform sound river management. For this to be successful, every organisation involved in the RHP has to: � have a clear understanding of the programme’s purpose and objectives; � agree on their respective roles and responsibilities; � accommodate the programme within their internal business and strategic

plans; and � work together in a collaborative and co-operative manner.

Reporting and information dissemination

Table 4.1 indicates colour codes, ecological categories and descriptions adopted for the data interpretation and reporting for the NAEHMP: RHP and Eco-Status of rivers.

� Rivers Client (windows application running on a desktop, also allowing data uploading from local databases to the national database – the Rivers Server); and

� Query Master (for extracting data − a local version running on the desktop and a server version running on the Internet).

*�"��7$+-� �� F��#��6��+��$

��#��F��#��(��Q��B��(;��(F��?��*F��Q��F��#��B�F(��K��?� 201

��7$-� ��"�� "��%� ��"�� )��FQ9��$

Ecological categories

Name �� Colour

A �� B��'�� /��

B 8�� =��"��'�� 8��

C *�� ?��'�� K��

D 9�� =��"��'�� F��

E ��'�� '�� 9��

F ;�� '�� ;�� '�� /��

A variety of other icons, http://www.dwa.gov.za/iwqs/rhp/state_of_rivers.html, are also used to express indices assessed and their status reflected by the colours in Table 4.1 above.The programme interprets and disseminates information in a variety of ways for different target groups. A broad range of stakeholders use the information generated by the RHP, ranging from the scientific community to water resources managers and planners, politicians and the general public [3].


A multi-temporal approach for identifying and mapping

changes in wetlands using satellite imagery

#V�z}`W�=$�9^}}`f

Wetlands are under threat due to human pressures. This investigation therefore aimed at developing a methodology for the accurate and efficient delineation of wetland areas using satellite imagery and other relevant spatial datasets. Summer and winter LANDSAT ETM+ satellite imagery were processed using various image classification techniques. These included the supervised, unsupervised and level slicing classifications procedures. The accuracy of each technique was tested against an existing wetland dataset. A ground truthing exercise was also undertaken. The highest accuracy (71%) was obtained by a supervised classification of a summer LANDSAT scene. The lowest accuracy (39%) was recorded by a 20 class unsupervised classification of a winter scene. The classification inaccuracies were attributed to changes in land cover as there seemed to be an overall loss of wetland areas. This study concluded that LANDSAT ETM+ satellite imagery was useful for detecting wetland areas during summer by using a high number of classes. This technique is also suited for the detection of both large and small wetland areas. Recommendations include: the use of summer imagery in a high rainfall period; the unsuitability of using winter imagery due to the spectral confusions created; the use of high resolution satellite sensors (SPOT) for monitoring purposes and the use of lower resolution sensors (LANDSAT) for mapping; the increased use of topographical modelling for wetland detection; the use of an appropriate scaled land cover database; and the use of field verification exercises for comparing classifications.


Introduction

There are a great variety of wetlands and they produce a remarkable showcase of natural resources. They also represent important ecological areas that support a wide range of vital processes, such as water resourcing and maintaining biodiversity. The wetlands also support different social activities within the areas in which they are found. It is essential to monitor and map these areas to ensure their continued existence. One of the most comprehensive definitions of wetlands was one adopted by the wetland scientists in the United States Fish and Wildlife Service who define wetlands as ‘land transitional between terrestrial and aquatic systems where the water table is usually at or near the surface or the land is covered by shallow water’ [1].Wetlands cover approximately 6,4% of the global land area and account for 24% of total global productivity [2]. Despite their importance, wetland habitats are being continually degraded to a point that they are not able to support normal wetland functions [3, 4]. Various countries and international bodies have introduced public understanding initiatives and legal protection mechanisms to help combat the destruction of these natural resources. Individual countries have undertaken wetland inventory procedures in an attempt to optimally manage the wetland areas under their authority. South African environmental authorities have emphasised the importance of finalising a suitable methodology for mapping wetlands [5]. There is an urgent need to evaluate the use of satellite imagery to map wetland areas. With increasing developments in both the Geographical Information System (GIS) and the remote sensing environments, there is now enormous potential for combining advanced technologies to develop feasible ways of mapping wetland areas. This study presents an investigation that utilises multispectral satellite imagery within a GIS to map wetlands in the Midmar sub-catchment area in KwaZulu-Natal.

The study area

The study area lies between 29°04’S 29°49’E and 29°32’S 30°25’E (Figure 4.22) and falls within the Lions River magisterial district. In terms of hydrology, the Mgeni River forms the main axis of the larger catchment along which four major water supply bodies are located. These include the

Midmar, Albert Falls, Nagle and Inanda dams. The Midmar catchment is drained by the Mgeni River and both its tributaries, the Lions River and the Dargle Stream [6].

*�"��7$++� =�� ?��$��F��;��"��B��B��O��)��

��#��F��#��(��Q��B��(;��(F��?��*F��Q��F��#��B�F(��K��?� 203

Methodology

This study concentrated on the use of remotely sensed data, namely, LANDSAT Enhanced Thematic Mapper Plus (ETM+). Two scenes were chosen to represent different seasons (Table 4.2). An evaluation of rainfall data was done from December 1999 to January 2000 from weather stations within the study area in order to achieve a maximum contrast of wet and dry conditions for the identification of wetlands [7].

��7$+� (��"�� "� ��$�

��

��

��

��

#��

��

��

��

�

9��

:�F�

�

;��

��

��

/��

-$�=

��

#��

��4�

��?

�

=4+-

-�5,

5,¬,

5,-3

3,4-

+

-333

:4:-

+��

��

�!

-�5)

,)5,

,

WINTER IMAGERY

��/��-%�+%�6%�7%��%�4��+5%�� !

/��$-��$+��,�� !

/��5��9�� -�� !

+$�=

��

#��

��4�

��?

�

=4+-

-�5,

5,¬,

5,+,

,,-+

,

+,,,

:-:+

,

��

��

!

-�5)

,)5,

,

SUMMER IMAGERY

��/��-%�+%�6%7%��%�4��+5%�� !

/��$-��$+��,�� !

/��5��9�� -�� !

�� $� �� "�� "�� "��%��"��'�� '��$��-,�

Figures 4.23 and 4.24 show both the summer and winter LANDSAT ETM+ images in false-colour composite, which were acquired for the research.

*�"��7$+6� *��)��*;;!��=��#��?��"�.


*�"��7$+7� *��)��*;;!��=��#��?��"�$

Prior to image processing, all datasets were re-projected according to the satellite image projection, namely, Transverse Mercator (Spheriod), WGS84 (Datum) with a central meridian of 31 degrees. A histogram peak-cluster analysis was performed. The CLUSTER procedure is fast and effective in uncovering the basic land cover structure of the image by determining the number of classes into which the image can be classified [8].Three classification procedures were applied to both scenes. These included an unsupervised (using 20 and 255 class categories), supervised and a level slicing approach. An accuracy assessment was done using ArcView 3.2 [9]. Each visually interpreted classification was converted to binary images (zero and one). The zeros represented non-wetland areas and the ones represented wetland areas as per classified image.

Results and discussions

Two unsupervised classifications using 20 and 255 classes were performed. The unsupervised 20 class classification of the summer image showed wetlands and water bodies that could be identified by their spectral response (blue), their proximity to perennial rivers and their identification on the topographical sheets (Figure 4.25). The winter image proved difficult to classify, as there seemed to be no distinct spectral signature for wetlands and water bodies, except large water bodies such as the Midmar Dam (Figure 4.26). An evaluation of the classification indicated that the smallest identifiable wetland was between 6-8 pixels, which represents a ground area of approximately 180 square metres.This was also observed in the first field verification. The unsupervised classification (summer and winter images) using 20 classes produced low classification accuracies for both images. The overall summer classification accuracy (polygons with a wetland signature) was 55%. The winter image classification revealed an accuracy of 39%. The low accuracies were attributable to using a small number of broad classes (20 classes). The wetland data [10] identified wetland areas that were inconsistent with the classified image.

��#��F��#��(��Q��B��(;��(F��?��*F��Q��F��#��B�F(��K��?� 205

*�"��7$+�� "�� +,� �� '�� !� ��"� �� '�� !��!$

*�"��7$+�� "��+,��'�� !��"�� '�� !��!$


*�"��7$+4� �� '��"��"�$

The unsupervised 255 class classification showed wetlands in the study areas that were easily classifiable. The classification of the winter image proved problematic because of the spectral confusion between wetland areas, burnt areas, firebreaks and shadows of trees and slopes [4]. In terms of the accuracy assessment, a random sample was selected and checked against the verified data. The summer scene produced a relatively high accuracy level of 71% whilst the winter image produced an accuracy of 47%. A visual analysis of the classified summer and winter images indicated the following:(a) The summer classified image showed both large and small open water

areas and wetlands. Smaller open water areas were checked against the topographical maps in order to distinguish between farm dams, reservoirs, and wetland area.

(b) The winter classified image indicated spectral confusion between wetland areas or open water areas and shadows within forested areas, shadows of steep slopes, clouds and burnt areas.

The supervised classification was done by selecting sample areas within both the winter and summer images. In both the summer and winter images three large training sites were automatically chosen using the image processing software. The accuracy of each classified image was determined by superimposing the wetland data and thereafter selecting random samples. The supervised classification for both winter and summer images showed

improved classification accuracy for the summer image. 65% of wetlands were correctly classified in the summer scene, but only 41% for the winter scene. Although the accuracy of the summer classification differed to that of the summer classification using 255 classes, the supervised classification showed both large and smaller wetland bodies with an accurate ‘fit’ when compared to the wetland data (Figure 4.28). The supervised classification also showed distinct wetlands around river tributaries.

*�"��7$+5� ��"��"�� '�� $

��#��F��#��(��Q��B��(;��(F��?��*F��Q��F��#��B�F(��K��?� 207

Using the 15 metre panchromatic bands of both the summer and winter LANDSAT scenes, a level slicing method was used to detect wetlands. The spatial resolution of the panchromatic bands was previously used in other studies to indicate wetland areas [4, 7]. Both panchromatic bands (winter and summer) were subjected to the same procedure of identifying large wetlands areas within each image and then masking the areas with other spectral characteristics using different colours. As can be seen in Figure 4.29, the summer image produced a relatively high level of accuracy (65%) in terms of locating open water bodies, wetland areas and wetlands within forestry plantations. The use of the wetland data to evaluate the results showed that the classified image (summer) produced a good estimation of both small and large wetland areas.The difference in spatial resolution of the panchromatic bands made little difference to accuracy of recognising wetlands on the winter scene. The results showed similar spectral confusions (slope shadows, burnt areas and fire breaks) in the post-evaluation analysis. The winter classification produced an accuracy of 45%.

Field verification exercise

A field verification exercise was undertaken by visually verifying mapped wetland areas along selected main roads. The most accurate classification (summer-255 classes) was chosen for the field verification exercise as it showed both large and small wetlands classified from the satellite imagery but not present on the wetland data set. The verification exercise was effective and successful in identifying areas mapped as wetlands that were not included on the wetland dataset.Figure 4.30 shows sites 21(a) to 26 in the field verification exercise. The following is evident:(a) The classification (255 classes) identified both large and small wetland sites

which were positively identified during the field verification exercise.(b) Many wetland sites identified using satellite imagery differed in size and

extent when compared to the wetland data that was originally collected using aerial photography.

(c) Many wetlands sites in the study area have been drained and so do not appear in the classified image.

(d) The larger wetland areas have either been drained or impacted by some sort of land use change that renders them smaller on the classified image.

*�"��7$+3� �� "��"�� '�� $


*�"��7$6,� *�� '�� +-�� +�!� �� )+�� '�� $

Conclusions and recommendations

This research investigation showed the relevance and applicability of using LANDSAT ETM+ imagery to map wetland areas. The study also demonstrated the applicability of using summer LANDSAT images to distinguish the visible and spectrally defining characteristics of wetlands. The different image processing techniques that were used to differentiate wetland areas indicate that a classification with a large number of classes is useful for identifying both large and smaller wetlands, although the process is more time consuming. The field verification exercise confirmed the viability and usefulness of using LANDSAT ETM+ imagery for wetland delineation purposes.This research investigation shows that satellite imagery can be used to update and verify wetland-related spatial information. The emerging satellite technologies and image-processing techniques will further enhance the mapping of wetlands from satellite imagery [11, 12]. Human impacts on environmentally sensitive wetland areas can be assessed in future by repeatedly mapping changes in this way. This can form the basis for a national monitoring and management plan.

F(8Q�� ;��@��/��


��9��Q

��


��#��F��#��(��Q��B��(;��(F��?��?�F(��(��Q�F��(F��?�� 211

consequences and responses in respect of sea level rise along the coast of southern Africa. Andrew Mather then follows with a detailed study of sea level rise and the anticipated impacts along the east coast of South Africa. It is anticipated that, even with the modest sea level rise projected for the near future, extreme coastal storms will cause ever more damage to coastal infrastructure and services. This damage is placed in perspective through an examination of the extensive coastal erosion accompanying disastrous extreme events along the KwaZulu-Natal coast from Alan Smith and his co-authors. Finally, the anticipated impacts of sea level rise along the coastline of the City of Cape Town and possible adaptation measures to reduce risks and alleviate costs are considered by Geoff Brundrit and his co-authors.The emphasis then turns to specific topics within the broad field. Kim Bernard, Wayne Goschen and Juliet Hermes investigate the influence of climate change on coastal upwelling along the west coast and the potential impacts on the marine resources. This is followed by a shift to long-term monitoring of coastal marine biota, and Albrecht Götz explores the potential of marine protected areas. Human activities can join climate in being drivers of change along the coast of South Africa, and their role along rocky shores is discussed by Charles Griffiths and his co-author. Seabirds can be used as indicators of the state of the marine environment, and Rob Crawford and Peter Ryan demonstrate the value gained from long-term monitoring of their distribution, all along the coast of South Africa.The final two contributions focus on recent changes in distribution in two commercially important marine resources and explore causes and effects and the possible links to climate change. Carl van der Lingen and his co-authors take a close look the pelagic fish stocks of anchovy and sardine in the shelf waters off South Africa, and Andy Cockroft discusses implications of the large scale shifts in the west coast rock lobster.


Introduction8Vx��/\{WX\^j

Continuing this section on States and Trends in the Aquatic Environment, the focus shifts from freshwater resources, wetlands and rivers and reaches to the sea and the coast, and the marine inshore environment of South Africa. There are real contrasts in this area, ranging as it does from the sub-tropical east coast with its offshore corals and extensive bio-diversity, to the great wealth of biological resources to be found in the highly productive upwelling areas off the arid west coast.The marine inshore environment also approximates to the Exclusive Economic Zone (EEZ) of South Africa, stretching for 200 nautical miles out to sea from the 3 000 km long coastline of the African continent and from the tiny Prince Edward Islands far offshore in the South Indian Ocean. The EEZ generates increasingly significant benefits for the people of South Africa and contributes substantially to the national gross domestic product. These benefits include sustainable fisheries for food, safe ports and shipping lanes for international trade to and from South Africa, and the cost-effective retrieval of oil and gas and other mineral deposits, such as diamonds. The EEZ also forms the basis for an extensive recreation and tourism industry. All this is achieved despite the hazardous nature of this offshore marine environment with its exposure to the winds and storms of the vast oceans to the south.A healthy marine environment is an important factor for economic development, social well-being and human quality of life. An assessment of the state of the marine inshore environment around South Africa will set the baseline against which to measure trends, especially as far as climate change is concerned. This is the objective of the chapters to follow.The section is introduced by an emphasis on the impacts of climate change with a suite of four contributions on the influence of climate change on coastal sea level. First, André Theron provides a general review of causes,

211



Climate change, sea level rise and the southern African coastal zone

A general revue of causes, consequences and possible responses

�WX\®��$��zV\xW

This chapter gives a brief revue of the likely physical coastal zone impacts due to expected climate change. To mitigate the detrimental impacts of climate change on the southern African coast, research is and should increasingly be directed at improving understanding of what is happening to our coastline and what is likely to happen as climate change intensifies.

Why study coastal climate change impacts?

Predicted climate change and sea level rise have far-reaching consequences for southern Africa’s coastal provinces. Over 80% of the southern African coastline comprises sandy shores susceptible to large variability and erosion (Figure 4.31). The problem with sea level rise is not just the relatively modest mean predicted, but its interaction with changing storm intensities and wind fields to produce sea conditions that overwhelm existing infrastructure.

Sea level rise

Projections of sea level riseRecent carefully calibrated observations from satellites show that the sea level rise from 1993-2006 is 3,3+/–0,4 mm/year [1]. The Intergovernmental Panel on Climate Change (IPCC) AR4 Report [2] concludes that anthropogenic warming and sea level rise would continue for centuries due to the time scales associated with climate processes and feedbacks, even if greenhouse gas concentrations were to be stabilised (Figure 4.32).

*�"��7$6-� �� ;�� "��$� ��$� ��%�#��+,,5�

*�"��7$6+� ��"�� -35,)-333��!��@��$��+��;��;��"��+,,4�� 9�� /��$� ��"� 8�� (� ;�� *�� F�� (��"�� 9�� ;�� ;��"�%�*��$-%�*�"��-$�;��"��B��9��

��#��F��#��(��Q��B��(;��(F��?��?�F(��(��Q�F��(F��?�� 213

Estimates of sea level rise for southern AfricaComparisons between about 30 years of South African tide gauge records and the longer-term records elsewhere show substantial agreement. A recent analysis of sea water levels recorded at Durban confirms that the local rate of sea level rise falls within the range of global trends [3].

Accelerated sea level riseThe probability of sudden large rises in sea level (possibly several metres) due to catastrophic failure of large ice-shelves (for example, [4]) is still considered unlikely this century, but events in Greenland (for example, [5]) and Antarctica (for example, [6, 7]) may soon force a re-evaluation of that assessment. In the longer term, the large-scale melting of large ice masses is inevitable.

Some important potential consequences of global warming on the southern African coast

WindAverage wind velocity is expected to increase in all seasons in South Africa. If, due to climate change, winds become only 10% stronger, then wave height increases by 26% and coastal sediment transport rates potentially increase by 40% to 100% [8].

StormsThe expected increase in storm activity and severity is likely to be the most visible impact and the first to be noticed. For example, higher sea levels will require smaller storm events to overtop existing storm protection measures (for example, Figure 4.33).

*�"��7$66� ��"�� ;��%��+,,5!�� "��"�$��$��

InfrastructureBreakwaters (Figure 4.34), revetments and seawalls, which protect infra-structure such as harbours and houses from direct wave action and under scouring, will require more maintenance. The longevity of such structures and facilities will be reduced.In some instances, roads and railway lines have been located too close to the sea (Figure 4.35). The foundations of such structures could be underscoured due to the combined impacts of sea level rise and increased sea storms. This could result in structural damage and potentially fatal accidents if not rectified.


*�"��7$67� ��"��$��$��

*�"��7$6�� $��$��

Other consequences

Some other consequences of global warming on the South African coast include the following: � Altered freshwater inflows and sea conditions (waves, water levels and

sediment) will (further) reduce the environmental function of some estuaries, which will impact fisheries (for example, nursing grounds). Also, estuaries are exposed to changes in salinity regime.

� Shorelines are very sensitive to sediment supply and budgets – erosion is influenced by various factors affected by climate change.

Examples of complexities, thresholds, discontinuities and non-linearities

These are some examples of complexities, thresholds, discontinuities and non-linearities: � A certain beach width is, for example, required for natural variability in

shoreline location and certain ecological functioning. Once the average beach width reduces to less than this amount (due to the ‘squeeze’ between fixed present development and sea level transgression up the coastal slope), there will be detrimental and progressive impacts on the ecology and on anthropogenic development (such as evident in Figure 4.36).

� Sediment transport and thus erosion is exponentially related to wave height, which in itself is not linearly related to (increasing) wind conditions. Some impacts of increased sediment transport would be particularly noticeable where there are disruptions in alongshore transport or discontinuities. For example, harbour entrance channels that trap alongshore transport could trap much more sediment in future, requiring increased preventative (maintenance) and dredging (potentially in the order of 50-100% more), which will lead to higher costs.

��#��F��#��(��Q��B��(;��(F��?��?�F(��(��Q�F��(F��?�� 215

*�"��7$6�� O��)��%�?��+,,4$��#$�9��

Identification of some of southern Africa’s most vulnerable areas and local issues

The most vulnerable areas along the coast will almost invariably be located where problems are already being experienced. In most cases these are the areas where development has encroached too close to the high-water line (as illustrated by the example pictures), or at too low an elevation above mean sea level.

NamibiaBreaching of the Walvis Peninsula by the sea poses a real threat. Because the peninsula is so low-lying, both sea level rise and increased sea storminess could greatly increase this risk. A large breach of the Walvis Peninsula would have disastrous consequences for Walvis Bay.Increased storminess due to climate change would impact costs (for example, increased beach-wall maintenance and protection) and increase the difficulty

of coastal diamond mining in certain areas. However, it appears that apart from some important potential impacts in the Walvis Bay area, the Namibian coastline is relatively invulnerable to climate change impacts (compared to many other countries).

South AfricaFortunately, due to the relief of much of the South African coast and the location of existing developments, relatively few developed areas are sensitive to flooding and inundation resulting from projected sea level rise (to 2100).The most vulnerable coastal areas (resulting from predicted climate change impacts) that have been identified are northern False Bay, Table Bay, the Saldanha Bay area, the Southern Cape coast (for example, Figure 4.37), Mossel Bay to Nature’s Valley, Port Elizabeth and developed areas of the KwaZulu-Natal coast.

*�"��7$64� Ad hoc� ��"�� %� �� ;��%� +,,5$��$��


According to Tol [9], by 2100 South Africa will lose some 11% of its wetlands due to full coastal protection measures and structures erected to mitigate sea level rise impacts, making South Africa potentially the fifth most vulnerable country worldwide in terms of wetland losses only.

Mozambique

Tol [9] predicts that by 2100 Mozambique will have lost 1,3% of its dryland area due to sea level rise, potentially making it the fifth most vulnerable country worldwide to sea level rise.Fringing reefs are found along some areas in Mozambique. These reefs comprise tough, algal-clad intertidal bars composed largely of coral rubble and provide protection from wave attack to the inshore areas and beach sands that are susceptible to erosion [10]. If the coast is subjected to the predicted sea level rise, and the upward growth of the reef bars fails to keep pace, then their protective role will be diminished.

*�"��7$65� ?�>��"�$��$��

The port cities of Maputo and Beira are likely to be some of the most problematic areas in Mozambique from a climate change perspective and appropriate local planning and adaptation measures should be initiated in the short-term.

Possible responses and guidelines to mitigate climate change impacts

In general, regarding developed areas and existing infrastructure, southern African states have very little adaptive capacity. Where this is deemed acceptable and space permits, the best policy in the long-term is probably not to combat coastal erosion and to allow the natural progression of coastal processes. In any case, our ability to halt the coastal impacts of climate change on a large scale is virtually non-existent and may well lead to other detrimental impacts.Tol [9] predicts that adaptation would reduce impacts by a factor of 10 to 100 (globally), and that adaptation would come at a minor cost compared to the potential damage incurred. This strongly emphasises the need for setting and implementing adaptation measures sooner rather than later.Each vulnerable stretch of coastline should be studied in terms of aspects such as wave energy, sand budgets, future sea levels and potential storm erosion setback lines, including accounting for at least a Bruun-type erosional response, as well as expanded profile envelopes.In southern Africa, we need to develop decision-support tools such as maps, a geographic information system (GIS) database and reports for use by the coastal management community. This will lead to a coastal vulnerability classification scheme whereby realistic scenarios of future coastal conditions can be used to support adaptive management and the development of coastal policy.Our best ‘adaptive capacity’ appears to lie in planning and research-related initiatives, such as quantifying increased storminess, and determining appropriate coastal erosion and development setback lines. We must also expand and adapt current plans for disaster management to include measures for more intense meteorological and metocean events.

��#��F��#��(��Q��B��(;��(F��?��?�F(��(��Q�F��(F��?�� 217

Conclusions

Locally applicable methods have to be developed urgently to realistically quantify the impacts along the southern African coast. To mitigate the detrimental impacts of climate change, we have to understand the adaptation options available to southern African society, which are considerably different from First World approaches and still largely undefined.Quantitative information remains largely unavailable and the resulting, somewhat speculative, predictions presented here are uncertain. Some important potential consequences of global warming on the southern African coast are highlighted, and there is a clear and urgent need for improved understanding of these issues and, especially, predictive capabilities.


Sea level rise and its anticipated impacts along the east coast

of South Africa�WX\V|��$�?`jzV\

This chapter focuses on likely impacts along the sandy east coast of South Africa. Sea level rise and coastal erosion is modified by a range of differing influences that result in very specific and localised responses. This section explores several of these factors by way of examples. What is evident is that additional research at a fine scale into the behaviour of the coastline is needed if we are to understand and plan properly into the future.

Introduction

The east coast of South Africa is typified by its sand shoreline with rocky outcrops or headlands that break up the coast into distinct bays. The sand is predominately composed of quartz [1] and has a grain size of between 0,3 and 1,0 mm. This is a high energy coastline with large waves and swells. Summers are dominated by winds and waves from the northeast and winters by winds and waves from the southeast. This results in a cyclical movement of sand offshore in winter and onshore in summer. During winter the beaches are at their narrowest, experience the largest storm events and are therefore the most vulnerable to raised sea levels. Large storm events are not uncommon along this coastline and when several events occur at close intervals these can cause enormous damage to the coastline. This was dramatically shown in the storm event during March 2007 along the KwaZulu-Natal coastline (see the next chapter by Alan Smith et al.). This particular event was significant as it provided a preview of the type of situation which may occur more often into the future.


Factors influencing sea level rise at a local level

Many authors have determined that global sea levels are increasing [2]. The rate of sea level rise at Durban is 2,7±0,05 mm/year [3]. However, the rate of sea level rise at a particular location can vary. These variations can be caused by large-scale global circulation systems, such as ocean current circulation between large irregular ocean basins, to much more localised influences, such as barometric pressure changes. This section focuses on the local role of two influencing factors, namely, the influence of the warm Agulhas Current and local vertical crustal movement.

Agulhas CurrentOne of the largest contributors to global sea level rise is the warming and expansion of the water in the oceans. The current view is that even if warming could be stopped now the lag in thermal expansion of the oceans will continue until the year 2300 [1]. The East Coast is strongly influenced by the Agulhas Current, which brings warmer equatorial water to the coastline. This warm water, in contrast to the surrounding seawater, is lighter and therefore yields its full thermal expansion component in the form of sea level rise. A warming trend in the Agulhas Current will result in increased thermal expansion and sea level rise. Intensification of the Agulhas Current in the 1980s has been observed and is discussed by Mathieu Roualt et al. in the section on The Marine Offshore Environment.

Local vertical crustal movementLocal vertical crustal movements affect the relative change in sea level experienced at different locations along the coastline. Observations from the Hartebeesthoek Radio Astronomy Observatory show that the land mass is rising at different rates. In the north, Richards Bay is rising at +1,11±0,25 mm/year, and in the south, Simon’s Town is rising at 0,29±0,18 mm/year [4]. Upward movement of the land mass is offsetting some of the rise in sea level.

Projected sea level rise

The amount and rate of sea level rise into the future is not known. Many authors have attempted to determine some likely projections based mainly on CO2 increases. Over the last few decades the science behind the models used to provide these projections has improved and the range has narrowed [5]. The current Intergovernmental Panel on Climate Change (IPCC) Report [1] gives a range (refer to the previous chapter by André Theron, Figure 4.32.) However, from a practical point of view, it is important that South Africa reach a consensus on the range of sea level rise that must be planned for. The eThekwini Municipality has been working on a range of scenarios for long-term planning. These are 300 mm, 600 mm, and to address recent concerns about glacial failure, 1 000 mm [6]. The scenarios are seen to be both believable (an important consideration when it comes to convincing the public) and workable. Clearly, if the situation changes drastically these figures will need to be reviewed.

Likely impacts along the shoreline of the East Coast

Rising sea levels will impact to a greater or lesser extent the whole sandy east coast coastline. Lower lying land adjacent to the coastline will be particularly vulnerable and there will be an even greater risk if the protective dune system has been removed. Rising sea levels will result in the inland migration of dune systems. For example, the dune system at Isipingo, adjacent to the Durban International Airport, has been retreating inland at a rate of between 0,7 and 2,1 m/year [7]. Provided there is space to allow this movement there is no real threat behind transgressive dunes. Any area in which urban development has replaced the dune system is vulnerable (Figure 4.39). Without the protective barrier to buffer storm events these areas will receive regular inundation and erosion (Figure 4.40).

��#��F��#��(��Q��B��(;��(F��?��?�F(��(��Q�F��(F��?�� 219

*�"��7$63� �� "��$�� $

*�"��7$7,� #��"��)�� "��$��=$�)?$�8��

These areas can be protected provided sufficient money is available. Recommended methods of protection will vary from site to site. For example, beachfronts, which rely on tourists visiting the sandy beaches, would be well advised to use a soft engineering approach [8]. In some cases the beaches will need to be renourished with sand. Renourishment is the dredging of sand from off-shore sources and pumping this material to the beach. This process provides a renewed buffer against erosion. It is expensive at around R50/m3 and is not permanent and so needs to be undertaken at regular intervals.Estuaries are also vulnerable to changing sea levels. The estuaries along the East Coast consist mainly of temporary open-closed estuaries. The closed

condition is achieved by a beach bar which closes the estuary mouth. These estuaries will be driven inland by the continued migration of the beach bar inland. Storm events on a raised sea level will wash marine sediment over the bar into the estuary. The additional sediment will fill the estuary basin and effectively reduce its scouring ability when the estuary’s bar is breached. This will slowly reduce the functioning and productively of the estuaries and will have consequences for fish stocks in the oceans.Locations in which ancient dune formation occur, such as the Bluff in Durban and other major dune systems along the Zululand coast [2], will experience undercutting of the base of the dune, which will result in large slip failures.


These failures will provide additional sediment to the longshore transport regime but will endanger infrastructure located seaward and along the front slopes of these dunes. Figure 4.41 shows the situation at the base of the Bluff headland in Durban. The figure shows the progressive retreat inland on the high water mark (HWM) (here defined in accordance with the Integrated Coastal Management Act (2009) [9]) for 300 mm, 600 mm and 1 000 mm sea level rise scenarios [6].There are two consequences of this sea level rise. Firstly the sewerage infrastructure, which services the whole of the Durban CBD and the residential suburbs on the Berea, is located on the beach. This facility collects the incoming sewerage flows and undertakes a primary screening of the inflows before pumping the sewerage off-shore through an undersea outfall. It can be clearly seen that the installation is under risk even before 300 mm of sea level rise is realised. The second consequence is the undermining of the toe of the ancient dune. This undercutting will result in slips along the steep seaward facing slopes. For means of illustration, the potential slip failure zone (coloured transparent red) is shown for 1 000 mm of sea level rise. Buildings located at the top of the Bluff (some 80 m high) will be in danger of sliding down the dune side. This scenario is also likely to occur in locations along the portion southwards to Amanzimtoti.

Other influences and impacts beside sea level rise

While this section is dedicated to the impacts of sea level rise it would be irresponsible not to mention other man-made influences which will have a significant bearing on the position of the coastline in the future. The two keys influences are the harvesting of sand from rivers for building purposes and the construction of dams for the collection of potable water for human needs.

Sand mining in riversHarvesting of sediment from rivers, commonly called sand winning, is an important facet of the construction industry. The sand is a vital ingredient in the production of the concrete required for the construction of buildings and infrastructure, such as roads, bridges and stadia. The ideal type of sand

required by the construction industry has unfortunately the same grain size as that required to replenish and build beaches. All sand winners are required to have a permit; however, in practice illegal sand winners outnumber the legal sand winners by two to one. The reduction of the flow of sand to the coast by sand winning is estimated to be approximately two-thirds of all available sediment [10].

Dam construction in riversDams constructed over the previous century in some of the main water (and sand) producing catchments for the needs of an expanding population have also had a significant impact on the future position of the coastline. Firstly, these dams are constructed in the main channels of rivers and as a result trap the sediment streams which would ordinarily pass down the rivers depriving their contributions to the coast. Secondly, the sediment trapped in the dams takes up valuable storage space at the bottom of the dams. This reduces the capacity and the potable water yield of the dams. All our dams are slowly filling up. Solutions are being sought, such as dam wall raising (Hazelmere dam), and new dams are planned (Spring Grove dam), but the problem will ultimately lead to the closure of these dams as they become completely filled with sediment (Shongweni dam). The reduction of the flow of sand to the coast by all dams is estimated to be approximately one-third of all available sediment [10].

Conclusion

It is critical to understand the extent of the impacts of the combination of factors discussed in this chapter in order to form a picture of what a future coastline could look like. While some work is being undertaken, it is evident that much more work in this field is required before we can plan and adapt to rising sea levels and coastal erosion.

��#��F��#��(��Q��B��(;��(F��?��?�F(��(��Q�F��(F��?�� 221

*�"��7$7-� 9��"��"��/��%�#��?��!$��Q�?��"��$� F��Q�?��"�/��F��$��>��'��"��"��$



The 2006-2007 KwaZulu-Natal coastal erosion event

in perspective�}`W�?$��q^jz

�WX\V|��$�?`jzV\ �WX\®��$��zV\xW �^qxW�;$�/{WXf

=^k`��)?$�8{`kjV}}`

The KwaZulu-Natal coastline experienced three types of significant erosion during 2006-2007. The base erosion was tidally driven by the 18,6-year nodal tidal cycle. This was exacerbated by a large storm in March (2007) which left the coast in disequilibrium and vulnerable to further erosion by lesser storms during the 2007 winter erosion cycle. By October (2007) the summer depositional pattern had set in and most beaches capable of natural repair had recovered as much as 60%. Erosion patterns varied; the 18,6-year nodal tidal cycle (2006) and winter erosion (2007) were characterised by erosion hotspots, whereas the March storm erosion was laterally extensive. Future sea level rise will make coastal erosion more common and increase the risk of damage to coastal infrastructure.

Introduction

Most of the world’s coastlines are eroding [1], driven in part by global warming-triggered sea level rise (see Chapter by André Theron in this section). KwaZulu-Natal (KZN) has a high-energy coastline, which is generally eroding at rates of 20 cm to 1 m per year [2-4] (in line with world averages) [5], consequently, there is considerable seasonal and episodic fluctuation of the high water mark position [2-4]. Erosion rates vary along the coast but there is a clear link with coastal geomorphology. Coastal erosion is amplified by a sand deficit due to drought, sand mining, dam construction and unwise coastal development [6-8] and will increase in the future because of global warming-triggered sea level rise and increased storminess [9].

222

��#��F��#��(��Q��B��(;��(F��?��?�F(��(��Q�F��(F��?�� 223

Tidal erosion

The KZN coastline experiences regular erosion on the normal spring high tide which produces characteristic beach sand scarps. This is accentuated when associated with storm surf [10]. During 2006, scattered parts of the KZN coastline experienced strong equinoctial tidal erosion (March and September). October (2006) coincided with the 18,6-year peak nodal tidal cycle and a 2,3 m tide (highest astronomical tide) was measured. This very high tide was due to the Moon and Sun being at their closest to Earth and coinciding with the spring equinox. During this time Eastmoor Crescent in Durban suffered severe erosion (up to 30 m of beach loss). Historical photographs indicate that this location underwent similar erosion during 1989 and anecdotal sources talk about erosion in 1970 (Figure 4.42).

Storm erosion

A major storm struck the KZN coast on 18-20 March (equinox 2007) during the highest tide of the year. The significant wave height (Hs or average set wave) was 8,5 m with a maximum swell height of 14 m [11]. The oceanographic environment immediately prior to the March storm had been dominated by cyclone swells (2 to 4 m), consequently, the shoreline profile was already degraded and sand depleted [8].The storm tide and wave run-up reached areas that seldom experience marine water inundation and these areas were easily eroded. Wave run-ups in the Durban region were surveyed at +4 to +7 m above mean sea level (amsl) and on the rocky coastline of Ballito they reached at least +11 m amsl [8]. The highest wave run-ups were on the southern side of headlands [8, 11]. In areas of vegetated coastal dunes the run-ups were less than 3 to 4 m amsl. The total amount of sediment removed is unknown.The steepness of the KZN coast meant that the storm’s hydraulic head could not be dissipated landward as inundation, but had to be released as an erosive seaward storm-return flow. Exposed or shallowly buried wave-cut rocky-platforms amplified coastal erosion. In contrast, wave action was diluted by friction across wide sandy beaches. The March storm destroyed many of the longshore bars (surf bars) and moved the sediment offshore. The sediment *�"��7$7+� �� ;��%� #�� -353� �� +,,�%� �� $�

�F��?��


deposited below 10 m deep will not return to the beach and will be bound up in the offshore shoreface-connected ridge system [12].Large 8 to 10 m swells have been recorded during mid-winter storms in the KwaZulu-Natal Bight [13]. Tropical storm Imboa (early February 1984) produced 9 m (Hs) swells in the Richards Bay area [14]. Another storm, in April 1984, was reputed to have raised 10 m swells off the KZN coast [15]. To a first approximation, a storm with the magnitude of March (2007) or greater can be expected about every twenty-five years [16]. This suggests that the storm was severe but not extreme. The scale of property damage experienced (Figure 4.43) was due to inappropriate coastal development [8].

*�"��7$76� #��"�� /�� ?�� +,,4!� �� <�"� �� $��$�/��

Winter erosion (2007)

Winter erosion is driven by southerly swells that create a south to north current called the littoral drift, which causes the greatest erosion in the southern parts of bays. In summer it reverses causing a seasonal beach rotation [17], but the winter pattern dominates. In 2007, there was a one to two month time lag, due to seasonally calm seas, between the March storm

and the onset of the winter erosion, which lasted from May to the end of August. Erosion was restricted to specific erosion hotspots (EHS) located in the southern parts of sandy bays to the north of headlands.Winter erosion (2007) began with two large swells in May (Hs = 4 to 5 m). It was intensified by a winter storm on July 30 (Hs = 4,5 m) which coincided with a spring high tide. The last significant bout of erosion took place at the end of August during a large swell (Hs = 3,2 m), which also coincided with a spring high tide. Winter erosion rates of 0,6 to 10 m/day were achieved. In contrast, during the March storm as much as 40 m of coastal erosion occurred in a single day. At the conclusion of the winter erosion certain EHS had lost 40 to 100 m of beach. In some instances only an intervention prevented the coastal erosion reaching its natural peak (Figure 4.44).

Discussion

In 2006, the unusually high spring tides of the 18,6-year lunar nodal tidal cycle caused erosion at isolated EHS and made the coast vulnerable to further erosion. Although the March storm occurred some months after the highest tide of the 18,6-year cycle it still struck during an unusually high equinoctial spring tide. In order for the coast to return to a new dynamic equilibrium, the seabed profile needed to rise and to do this sand was required. Storm erosion had moved sand too far seaward for fair-weather waves to return it; consequently the only available source was further coastal erosion.The March (2007) storm erosion was laterally extensive; whereas the tidal and winter erosion was restricted to hotspots. Much of the KZN coastline comprises asymmetric (some are log spiral) sandy bays bracketed by rocky headlands or points. These bays are subject to megaripcurrent cells that are driven by the net south-to-north littoral drift and cycle sediment between the beach and the offshore bars [2-4]. Swell height, tides [18], bathymetry, wind and other currents amplify these currents. This erosion is strongly geomorphologically controlled [19] and occurs when the bedrock underlying the beach is sufficiently deep to allow shoreward head-cutting into the coastal dune system. Each bay contains a single or multiple megarip-current cell, identified by the presence of a megacusp, ranging from tens to hundreds of metres wide (Figure 4.45). Erosion was commonest at spring high tide,

��#��F��#��(��Q��B��(;��(F��?��?�F(��(��Q�F��(F��?�� 225

usually in concert with large, long-period swells and often associated with strong coast-parallel winds.The difference in coastal erosion types between the March (2007) storm and the 2006 tidal- and the 2007 winter erosion may be explained by water level and geomorphology. During the March storm (2007) the very high sea levels flooded some points and headlands, removing their topographic effect [20] and preventing megarip EHS activity [20]. Consequently, the stretch of coast responded with lateral erosion as opposed to EHS.In urbanised areas, coastal dune cordons had been impacted on by development, either indirectly or directly, to the point that they could no longer function. Thus these dunes were incapable of acting as either a storm defence or as a bank for making good sand loss [8, 12]. The shortfall had to be made up from beach and dune erosion, hence coastal erosion became chronic during the winter of 2007. By September (2008) most of the sandy beaches affected by the erosion event of 2006-2007 had been restored to at least 60% of their pre-erosion width. Pristine coastal dunes had become re-vegetated and in some instances fore-dunes replaced. In urban areas the eroded coastal dunes had to be

*�"��7$77� (��F��%��>�� %�w��+,,��!��w��+,,4��!$�� "�� $��(��

*�"��7$7�� ;��)��"�� "��>�� $��=$�8��


artificially replaced using synthetic geotextile sandbags. Between March and September (2008) there were six storms with Hs = 3,5 to 4,0 m. Two of these storms occurred during comparatively low spring tides; the rest occurred towards neaps. Only minor coastal erosion was associated with these storms indicating that a new dynamic coastal equilibrium had been attained.

Historical erosion comparisons

The maximum 2006-2007 high water mark retreat values occurred at locations of known large historic variation [2-4], thus allowing a predictive capability. What is clear is that in many cases the 2006-2007 erosion events resulted in cumulative erosion that was less than the historic maximum.

Conclusions

� Between 2006 and 2007 the KZN coastline underwent three significant erosion events: 18,6-year nodal cycle erosion (October 2006); large storm erosion (March 2007), which coincided with the March equinox; and catastrophic EHS winter erosion.

� Storm water level and geomorphology are key factors in dictating erosion type. The March storm (2007) sea level caused laterally extensive coastal erosion, destabilised the coast and led directly to the catastrophic EHS winter erosion of 2007.

� Cumulative erosion figures are comparable to, and in some cases less than, the historic variation of the high water mark. Areas vulnerable to erosion can be predicted.

� In some urbanised settings interventions were required to save seafront property and infrastructure.

� By January 2008, the rural coastline had recovered to at least 60% of the pre-erosion condition in most cases. In urban areas, although the beach sand came back, the dunes were unable to facilitate a natural repair and had to be artificially stabilised using synthetic geotextile sand bags.

� Erosion is expected to increase due to sea level rise and the increased storminess; consequently, the 2006-2007 events should serve as a warning to coastal residents and planners.

��#��F��#��(��Q��B��(;��(F��?��?�F(��(��Q�F��(F��?�� 227


Sea level rise for Cape TownImpacts and adaptation

8Vx��/\{WX\^j �WjxW�;`\j|\^�zj

8Vx��#V__V\ ={�^WX`�*`^\z{\kj

8\V��V}x�kV

The City of Cape Town administers approximately 240 km (around 60 km are in the Table Mountain National Park) of coastline, arguably its single greatest economic and social asset. Global climate change predictions suggest that sea level rise and an increase in the intensity and frequency of storms may have a significant impact on such coastlines. The city has developed a Geographic Information System model to take estimates of future sea level rise, build them into illustrative scenarios of the resulting inundation of parts of the city, assess the risks to its infrastructure and services and identify the adaptation measures that could be adopted to mitigate those risks.

Introduction

This chapter addresses the threat of sea level rise along the beautiful 300 km coastline of the City of Cape Town and suggests what can be done about it.In the recent past, Cape Town sea level has risen roughly in line with the measured global increase of 2 cm each decade. That’s not much, so where’s the problem? There are two: ice melt over the polar land masses and bigger storms coming along more frequently.

*�"��7$7�� =��$�� "��"��"��?��>��"$�F��8��"��+,,3�


Changes in mean sea level are linked not only to the expansion of the oceans due to global warming, but also to the melting of the polar ice-sheets, which is now starting to occur. Predicting the extent and rate of polar ice-sheet melt is difficult, but a global mean sea level rise of metres is considered a real possibility within this century. As far as the Cape winter storms are concerned, the waves at the surf-break are often 10 m in height. At the coast, these waves can erode the sand dunes, damage coastal defences and flood low-lying areas. If a big storm comes at spring high tide, it can easily add a couple of metres to the background sea level for the duration of the event (Figure 4.47).

*�"��7$74� /�"��9��$��;��;��

The combination of higher mean sea levels and the probable increase in the frequency and intensity of storms will pose serious risks to infrastructure and services along the city’s coastline. These threats will be at their peak during winter storms and during periods of high tide, particularly in spring and autumn. The prospect of the sea reaching heights of well over 2 m above mean sea level becomes distinctly possible. To assess the risk, the City of Cape Town has developed a Geographic Information System (GIS), which includes details of the low-lying land, with infrastructure such as housing and industry and all the services, such as roads, electricity and water supplies.

This GIS can be used to assess the danger from particular climate change scenarios. Two separate situations are illustrated here: the increasing danger from big storm events and the longer-term prospect of permanent flooding from polar ice melt.

The big storm event now and into the future

At present, the worst case scenario is a big Cape storm occurring at the same time as a spring high tide. The waves at the surf break might exceed 10 m in height and the spring high tide will carry the big waves through the surf zone to the coast. The impact on the coast depends on the degree of protection. On a sheltered coast with good natural protection in the sea from reefs and kelp forests, the waves will dissipate through the surf, but the set up at the coast will still reach 2,5 m above mean sea level (amsl). However, on an exposed coast lacking this natural protection, the sea will reach up to 4,5 m at the beach, and on a very exposed beach with no natural protection at all, up to 6,5 m amsl. Cape Town hasn’t had this experience within living memory, but it did happen along the KwaZulu-Natal coast in March 2007, and this helped provide vital information as to what can happen in such circumstances. The storm caused over R1bn in damage to coastal infrastructure [1]. Coastal defences are designed to augment the natural protection and to turn exposed coasts into sheltered coasts. These defences might be seawalls or a fortified dune barrier providing additional protection to a coast or a breakwater protecting a harbour. Even on a sheltered coast, it may be necessary to use additional coastal defences to protect low-lying land behind. With this protection everywhere in place, and the City of Cape Town coast regarded as a sheltered environment, the coastal land at an elevation of less than 2,5 m amsl will be at risk of flooding during the worst case scenario. The GIS can provide the detail (Figure 4.48).The vulnerable areas are principally wetland areas associated with estuaries and coastal land that has been reclaimed from wetlands.What are the chances of such a damaging event occurring? Well, only a small chance at the moment. However, as the sea level rises, a somewhat smaller storm will result in the sea level reaching this same danger level of 2,5 m. In fact, over the next 25 years, it is almost certain that all parts of the Cape Town coast will be buffeted by at least one storm with this level of impact.

��#��F��#��(��Q��B��(;��(F��?��?�F(��(��Q�F��(F��?�� 229

*�"��7$75� 8(��"��+%��$

The sea would flood 25 km2 of the city’s low-lying coastal areas and threaten (in 2008 prices) R5,2bn worth of public infrastructure, private real estate and tourism revenue. It is unlikely that the city will be confronted by either the full extent of the risk, or the full cost in a single incident, as that would require the simultaneous rising of the sea at all points around the coastline. Rather, the figures represent the cumulative risk and costs over a 25-year period at all points along the coast. At the moment, the risk is low, but it will gradually increase over the 25-year period until the cumulative exposure reaches the full R5bn.The GIS can also focus on particular stretches of the coast, show infrastructure such as roads and electricity substations, and the implications of a breakdown in coastal defences. Figure 4.49 shows the situation at the Strand, on the False Bay coast, with the exposure to 2,5 m in blue, 4,5 m in red and 6,5 m in orange.

*�"��7$73� 8(��"��+%��!%�7%��!��%��"�!$


At some time during the next 25 years the sea will affect the areas in blue, swamping the beach, the coast road and the buildings behind with their electricity supplies. Should the coastal defences fail at the time of an extreme storm, the areas in red and orange will also be affected. The importance of maintaining and improving the coastal defences will be paramount.

Permanent flooding from polar ice melt

The threat from polar ice melt is quite different. It involves a 7 m rise in mean sea level, leading to permanent flooding of the land along the coast (Figure 4.50).

*�"��7$�,� 8(��"��4��!$

Once again, it is the reclaimed land and the wetland areas close to the estuaries that are vulnerable. This time the area affected has grown to 95 km2 (4% of the total land under the city’s jurisdiction). Until recently, this scenario was considered unlikely this century, but that has changed with the melting of glaciers and the polar ice caps in Greenland and West Antarctica. The value of the property, tourism sector and public infrastructure at risk would be close to R55bn. Progressive exposure to this cost will take place over the period taken for the polar ice to melt and the sea level rise to reach this height of 7 m above present day mean sea level.The sea level rise will lead to a new coastline, seen on the GIS at the land edge of the blue area. Here the tide will move in and out on a daily basis and remould the coastline, with a new high tide mark at well over 7 m above present day mean sea level. The GIS can again focus on particular areas of the coast and show the areas and services at risk as the sea gradually rises over time. This information can assist in understanding the order in which flooding will take place and in assessing what precautionary measures might be possible. Figure 4.51 shows what is expected to happen at Muizenberg.In the first period of sea level rise (up to 2,5 m) Zandvlei will gradually get bigger, swamping the houses on its fringe and affecting their services (in blue). The outlet to the sea will widen and then overwhelm the coast road (Baden Powell Drive), while the vlei will continue to grow bigger and move across the railway and into the residential areas to the north (in red). Finally, the dune barrier behind the coast road to the east will fail and the sea will reach into the False Bay Waste Water Treatment Plant.

The City of Cape Town’s approach to adaptation

What should be the city’s approach to adaptation to the potential impacts of sea level rise? The city can take proactive measures designed to counter sea level rise events and protect its existing infrastructure and services. In extreme cases, it may become more cost effective to abandon existing areas and to relocate to new areas on higher ground. Certainly, the city should decide not to place more of its investment in areas which are at risk of loss from the impacts of future sea level rise.

��#��F��#��(��Q��B��(;��(F��?��?�F(��(��Q�F��(F��?�� 231

*�"��7$�-� 8(��"��?��>��"��+%��!%�7%��!��%��"�!$


Pre-emptive measures and planned responses could significantly reduce the risk of sea level rise for the City of Cape Town. The first emphasis should be on socio-institutional responses to sea level rise. Table 4.3 summarises some possible responses. These responses are seen as most appropriate for the city and as a prerequisite for any engineered or physical approaches to adaptation.

��7$6� 9��;��;��$

*��"��

�� "�� =��

��

��"��

��"��

?��

(��"�� "

(��"��

#��"��

��>��;��9�� O��

��"��

;��)��"��

?��"��

��"��"��"

F��

��"��

9��"��

�� "��

#�� "

9��

�� "��)��

/��

��

/��"��

F��"��

F��%��%��

/��"�

��

��#��F��#��(��Q��B��(;��(F��?��?�F(��(��Q�F��(F��?�� 233


Climate change and coastal upwellingPotential implications for

South African marine resources

�^q��$�/V\W`\X �`fWV��$�8xk�zVW

w{}^Vj�;$�QV\qVk

By providing nutrients to fuel phytoplankton production, coastal upwelling stimulates biological productivity at all levels, driving the world’s major fisheries. One of the major forces driving this is coastal wind. Changes in the intensity and frequency of upwelling-favourable winds are predicted to occur as a result of climate change and climate variability. This will have significant implications for South Africa’s coastal and marine resources. In some instances coastal upwelling will be intensified, which may lead to the desertification of adjacent inland areas. Conversely, El Niño events tend to cause a reduction of upwelling-favourable winds and consequently result in a reduction in biological productivity.

What is coastal upwelling?

Coastal upwelling is a term used to describe the phenomenon whereby cold, nutrient-rich deep waters are transported to the surface. There are a number of mechanisms that drive coastal upwelling, but perhaps the most dominant force is that of prevailing winds. As wind blows over water it creates a net transport of water at right angles to the direction of the wind; in the Southern Hemisphere this movement is at right angles to the left, while in the northern Hemisphere net movement is to the right. This phenomenon is known as Ekman transport and is caused by a combination of friction and the Coriolis force. With a coastline present, the surface layers move

away from the coast and are replaced with water from below, resulting in upwelling along the coastline. On the west coast of South Africa, the dominant southeasterly winds blow parallel to the coastline. This result in a conveyor belt of water movement to the north and west, causing a net offshore transport of surface waters, thereby bringing deep, nutrient-rich cool water to the surface. Similarly, on the south and east coasts of South Africa, easterly and northeasterly winds result in coastal upwelling.Other forces that drive coastal upwelling involve changes in the intensity and position of major currents, for example, the Agulhas Current, in the case of South Africa. In areas where the continental shelf widens, such as the region south of East London, divergence of the Agulhas Current from the shelf and Ekman veering in the bottom layers of the current result in upwelling [1]. In addition to this, the formation of cyclonic eddies (those that flow in a clockwise direction) by the Agulhas Current as it begins to meander bring cold deep waters up to the surface. If these eddies are transported towards the coast they will contribute to coastal upwelling [1]. Globally, current-driven upwelling occurs typically along the eastern coastlines of the continents. On the other hand, wind-driven upwelling occurs along both the western and eastern coastlines, but is far more regular and intense along western coastlines. Along the South African coastline the process of coastal upwelling is extremely strong and persistent off the west coast, as can be seen from the satellite image of sea surface temperature (Figures 4.52 and 4.53). Although relatively weaker and less widespread, coastal upwelling along the east and south coasts of South Africa is likely to play an important role seasonally and on a localised scale (Figures 4.52, 4.54 and 4.55).


*�"��7$�+� �� ?�#(�� "�� "�� "� ��;��%��$��)��"��*��)��)��*�!��"��+7%�+,,6%��)��!��)��"��!��$��)��"��$�=��%��"��$�*��)��%��"��

��"�� "��"��$� Q��%� �� )��)��$�� %��%��"��&��"�%��)��%��)��"�� $��;��"��)��"��*��)��)��*�!�9��@��%��)8�*;%��F/(?�8��?��-%�+,,6�

��#��F��#��(��Q��B��(;��(F��?��?�F(��(��Q�F��(F��?�� 235

*�"��7$�6� �� $� F�� "� �� "��"�� "��"�� Syrachosphaera pulchra%� �� "��$��"��%��)��"��"��"�� $� �� "��"��"��$� �;��"�� w��>%�?�#(��F��F��%��:8�*;�

*�"��7$�7� ��"��$�/��"��"��$�9��"�� $�Q��%��%��$��'��""��"� ��"�� %�� "��"�� $��;��"��w��>%�?�#(��F��F��%��:8�*;�

*�"��7$�� 9�� $� �;��"��w��#��%�?�#(��=��F��F��%��:8�*;�


The role that upwelling plays in enriching coastal waters and elevating biological productivity has been studied globally, particularly along the western coastlines of the continents, including the west coast of South Africa. However, upwelling on eastern coastlines is likely to contribute to the biological productivity of those systems, too. Through the process of upwelling, nutrients are transported from the deep waters into what is termed the euphotic zone or the light zone. This region in the water column is where phytoplankton photosynthesis occurs, since it relies entirely on the availability of light. However, in addition to light, photosynthesis requires certain nutrients, such as carbon and nitrogen. Carbon is readily available in the surface waters, which are in direct contact with the atmosphere. The euphotic zone is, however, often depleted of nitrogen. The process of upwelling enriches the surface waters, enabling photosynthesis to occur [2]. During these conditions phytoplankton grow rapidly elevating the biomass at the bottom of the food chain (Figure 4.56).

*�"��7$�� #��$��;��"��$��:��:#��;��

This, in turn, allows for organisms higher up the food chain (herbivores and carnivores) to grow and reproduce. In this way, upwelling enhances biological productivity in the water column [3-7]. In coastal waters, upwelling provides an important source of nutrients and food (in the form of phytoplankton and zooplankton) to fish larvae as well as rocky shore filter feeding organisms, such as mussels and barnacles [8]. Coastal upwelling thus plays an important role in the productivity of many of South Africa’s marine and coastal resources.

How will climate change influence coastal upwelling and what will the implications be?

Climate changeClimate change is predicted to have an effect on the frequency, timing and intensity of coastal upwelling events by altering the prevailing coastal wind patterns [9, 10]. This would have significant consequences for coastal productivity and resources on both the western and eastern seaboards of South Africa. The implications of such a change are not completely understood for the east and south coasts of the country as little research has been conducted along those coastlines. However, research conducted on the west coast of South Africa as well as in other parts of the world suggests that changes in the timing and intensity of coastal upwelling will have severe and often detrimental effects on recruitment of rocky shore organisms [11] as well as the productivity of major fisheries [12-18]. In addition, the early life history of the sardine and anchovy, major pelagic fish resources in South Africa, involve transport along the frontal jets between the cold upwelled water and warmer offshore water. Increased upwelling may advect these early lavae too far offshore and diminish the return of juveniles to the productive inshore area along the west coast.Another mechanism through which coastal upwelling might be affected by climate change is the alteration of the velocities of major western-boundary currents (currents that flow along the eastern coastlines of the continents). For instance, evidence suggests that the strength of the Agulhas Current has increased since the 1980s [19]. This might influence the development of

��#��F��#��(��Q��B��(;��(F��?��?�F(��(��Q�F��(F��?�� 237

eddies, resulting in either increased or reduced occurrences, as well as an increase in shelf-edge upwelling with consequently colder inshore waters.In addition to altering the productivity and availability of marine and coastal resources, changes in coastal upwelling might affect regional climate [9]. Increasing land surface temperatures will elevate the atmospheric pressure gradient between the land and sea, resulting in stronger alongshore wind stress and subsequent acceleration in coastal upwelling [9]. Along the western coastlines of the continents, including the west coast of South Africa, the typical climate of those regions is driven largely by the occurrence of coastal upwelling. The generally clear conditions along western seaboards lead to strong daytime heating of the land, followed by rapid nighttime cooling [9]. Also, the cool onshore air flow is typically very low in humidity and for this reason many regions that are adjacent to persistent west coast upwelling are either semi-desert or desert (for example, the west coast of South Africa and Namibia). The more intense upwelling combined with the increasing land temperatures will exacerbate the problem by further increasing the alongshore wind stress, intensifying the upwelling even further. If coastal upwelling off the west coast of South Africa is strengthened this may contribute to the desertification of the adjacent land.

Climate variabilityEl Niño events are known to correspond with reduced occurrence of easterly winds [10, 20, 21]. For example, Pacific El Niño events result in a shifting of the South Atlantic high pressure cell northwards, resulting in more southerly winds in the northern Benguela and less winds in the southern Benguela. Known as the Benguela Niño, this is a major episodic event whereby warm tropical waters intrude southwards into the Namibian part of the Benguela Current [22]. These changes in prevailing winds would impact on the frequency and timing of wind-enhanced upwelling events along the coast of South Africa since north- and southeasterly winds cause upwelling along the west and south/east coasts respectively. Recent investigations on the effects of delayed upwelling indicate that the nearshore environment becomes depleted in nutrients, showing very low levels of primary productivity, and that the recruitment of rocky intertidal organisms may be reduced by up

to 83% [11]. This would significantly impact on the marine and coastal resources of South Africa, causing reduced stocks of rocky shore invertebrates and many important fisheries. Additionally, the southward intrusion of warmer water into the southern Benguela is likely to have significant effects on the distribution and productivity of many resources living along the southern African coastline and continental shelf.In addition to El Niño and Benguela Niño, there are other major modes of climate variability which are likely to influence the strength of coastal winds, including the tropical and subtropical Indian Ocean dipole and the Southern Annular Mode. These are all natural modes of climate variability, however, the impacts they have on our coastal regions are still not well understood. The chapter by Chris Reason and Juliet Hermes in the next section gives a more detailed description of climate variability.

What needs to be done?

Unfortunately, apart from concerted efforts to reduce carbon emissions, not much can be done to ensure that coastal upwelling systems along the South African coastline remain unaffected by global climate change. Since marine and coastal resources are likely to be negatively affected by a reduction in the occurrence of coastal upwelling, it is essential that these potential changes be taken into account by decision makers and resource managers. On the other hand, if upwelling is strengthened along the west coast, the subsequent drying of the adjacent land will result in severe water shortages, which should be planned for in advance in order to mitigate effectively.At present, in contrast to the Benguela Current upwelling system, very little is known about the influence of coastal upwelling on the biology of the south and east coasts of South Africa. Since the west coast upwelling system is different in many ways from the east and south coast systems, it would be pertinent to increase research efforts along the east and south coasts in order to gain a holistic view of the impact of global change on coastal upwelling along the South African coastline. In addition, long-term monitoring of coastal waters is required to detect changes and predict future scenarios.



Using Marine Protected Areas as a tool for long-term monitoring

of coastal marine biota�}~\V�zj�8¯j�

Despite their economic importance, the world’s fisheries have been poorly managed and are in a state of crisis. Marine Protected Areas (MPAs) have become a viable alternative to conventional management strategies which have failed to sustain marine biodiversity and fisheries resources. MPAs have the potential to enhance fisheries yield, and, if large enough and established in relatively pristine areas, can counteract the ‘missing baseline’ problem. This potential is essential to fishery management as it enables scientists to separate anthropogenic influence from natural variability and the effects of climate change through long-term monitoring in large MPAs.

Introduction

The world’s fisheries are a major employer and an important source of food for an exponentially increasing population. From the descriptions provided by Sauer, we learn that the total annual employment income from all fishery sectors in South Africa amounts to more than R400 million [1]. The sector’s importance can’t be overemphasised, in particular for developing nations [2]. There are numerous environmental pressures on the marine environment, but the impact of fishing has exceeded all others [3, 4] and has reduced fish stocks to well below the level of maximum productivity [5]. A glance at a selection of scientific and popular articles on fishing reveals a general atmosphere of pessimism on the state of fisheries in every quarter of the globe. In South Africa, Griffiths [6] examined long-term catch data for the hook and line fishery. He estimated that present catches are less than 10% of those reported during the first third of the 20th century. Upon scientific

advice and in terms of a provision in the Marine Living Resources Act (1998), the Minister of Environmental Affairs and Tourism in 2000 declared an emergency in the sector.Today there are widespread concerns regarding the ability of conventional approaches to manage fisheries sustainably [7, 8]. In order to develop an effective and practical management strategy for the future it is crucial to reflect on the performance of conventional single species approaches. The widespread failure of these conventional approaches in the past has led to intensive investigations into conceptually different strategies. As an alternative, an ecosystem approach advocates reliance on natural processes to restore and sustain fisheries resources by closing an area to exploitation.

Marine Protected Areas as an alternative management strategy

Marine Protected Areas (MPAs) have long been promoted as a viable alternative to single species protection in marine conservation, and recently, as an effective tool for fisheries management. MPAs may be the key to enhancing fishery yield where conventional management strategies have failed [9, 10]. Fisheries yield will increase as a result of the proximity of an MPA if there is substantial spill-over (export) into adjacent fishing grounds. This increase in yield can be sufficient to offset the loss of fishing ground to the MPA [11], particularly where MPAs are rather small (Figure 4.57).Today, many authors regard MPAs as a central component of precautionary fishery management and conservation of marine biodiversity [9, 10, 12-14]. With the establishment of the Tsitsikamma National Park in 1964, South Africa became one of the first countries in the world to implement no-take MPAs (MPAs that enjoy full protection from all types of extractive exploitation). Currently, 5% of the South African coastline is protected by no-take MPAs, while 18% is protected by some form of conservation [15].Irrespective of which fisheries management strategy or combination of such strategies is chosen, it is crucial to accurately evaluate our actions to be able to adapt future efforts. However, this evaluation process is complicated as measured trends in fisheries resources are not necessarily only a result

��#��F��#��(��Q��B��(;��(F��?��?�F(��(��Q�F��(F��?�� 239

separately, which will allow us to put resource assessments in exploited areas into perspective (Figure 4.58). South Africa has a relatively large number of differently sized MPAs (Figure 4.59). Managers and scientists should therefore be equipped to use these MPAs as tools for fisheries enhancement (small MPAs) and meaningful long-term monitoring (large MPAs).

*�"��7$�5� �� "��?9�� ")�� "$� �� "�� ?9�� >�$� �� ?9�� "�� "�� "�� "�� $� �� "��$�

of human exploitation and protection. Natural variability (for example, seasonality) together with climate change has an influence on the resource and is superimposed on the human influence. In other words, if resources recover in an exploited area it might be due to successful management (accurate catch restrictions, effective enforcement and high levels of compliance), a result of climate change having a favourable effect on the productivity of the ecosystem, or a combination of both. If we succeed in separating anthropogenic from natural effects, we can adjust our management actions in a meaningful way.

*�"��7$�4� �� ?9�� '�� $� �� "�� ?9��>�$� �� ?9�� "�� '��$

MPAs in South Africa

In South Africa, MPAs are useful as they conveniently provide us with examples of pristine ecosystems. This is, of course, if the MPAs are large enough to possess sufficient buffering capacity from the far-reaching effects of human disturbances. We can then monitor levels of natural change


*�"��7$�3� ?�� "� �� "� ?9�� !$��"��"��%��?9��$

Long-term monitoring methods

Long-term monitoring in the marine environment is particularly expensive and only sustainable if the applied methodology is cost effective. As a result, much research currently focuses on the comparative evaluation and development of new monitoring methods.For example, scientific angling is a low-cost monitoring method that provides researchers with long-term data series (Figure 4.60). Although very precise, angling is selective towards larger individuals of carnivore species and gives a somewhat skewed picture of the fish community. Diving surveys overcome this as they are non selective towards fish (Figure 4.61). However, the comparatively high costs involved in diving surveys have led many researchers to utilise a combination of both methods. Unfortunately, there is a problem, common to both survey methods, which affects the quality of the data collected. This is the so-called ‘observer bias’, which refers to the fact that anglers and divers vary strongly in skill and experience.

*�"��7$�,� ��'�� 9��-�!�$�� %��$��*�� Coastal Fishes of Southern Africa%��(�/��(�;��9��!�=��

��#��F��#��(��Q��B��(;��(F��?��?�F(��(��Q�F��(F��?�� 241

*�"��7$�-� ��"��"��%��"�� '��"��$

To overcome observer bias in monitoring, new methods, such as the baited remote underwater video (BRUV) method, are being developed. This method makes use of high quality digital video; a technology that has only recently become affordable. A camera mounted on a tripod is lowered onto the seabed from a boat where it records the fish community attracted by an attached bait container (Figure 4.62). The footage can later be analysed systematically on a computer where all the necessary information is readily available. This ensures objectivity (no observer bias) and a high quality of data analysis.

*�"��7$�+� ��/FB��'�� $�� "��"��$

Conclusion

MPAs have come a long way in improving marine conservation, fisheries resources and our ability to monitor and manage. Future efforts should focus on the systematic establishment of a national MPA network to ensure that the services they provide us with are available wherever necessary. Considering the vast distributional ranges of some marine species and the connectivity of biogeographic regions across oceans through large-scale current patterns, it is evident that international collaboration in marine research and management will be critical to ensure effective conservation. The future survival of our marine resources depends on our ability to monitor impacts and environmental change. Without this information sound decision making is impossible.



Human activities as drivers of change on South African

rocky shores;z`\}Vk�=$�8\^��^jzk

�W�V}`�?V`X

Rocky shores are amongst the most accessible of marine habitats and have been exploited by humans for thousands of years. Over the past few hundred years, however, both the intensity and variety of human impacts on rocky coastlines have increased significantly. This short chapter reviews the most important ways that humans have changed South African rocky shores. In probable order of importance, these impacts are: direct exploitation of coastal species; the introduction of non-native marine species; climate change; and habitat modification, pollution and disturbance.

Direct exploitation of coastal resources

Direct exploitation of coastal resources can take several forms, ranging from traditional subsistence exploitation, through recreational fishing to full-scale commercial activities. Subsistence fishers began exploiting mussels and limpets along South African shores tens of thousands of years ago and the remains of their meals can still be seen in the form of large shell middens, particularly along the west coast. The number of subsistence gatherers has increased dramatically over the past hundred years and this activity is now particularly intense in the Eastern Cape (Figure 4.63) and in KwaZulu-Natal. The most intensively targeted species are mussels and limpets, but at least 30 other species are taken, including winkles, whelks, octopus and redbait [1].

*�"��7$�6� ?��;�� $��;$=$�8��

Rates of shellfish extracting in the Eastern Cape can reach over 5 500 kg per km of rocky shore [2]. Not surprisingly, this has resulted in marked reductions in both the average size of mussels and in their density. Indeed, so few large mussels remain that the rate of settlement of mussel larvae has become severely reduced over the entire region [1]. Intensively-exploited shores are now dominated by barnacles, coralline algae and other inedible species. The solution to this problem can only be achieved by controlling exploitation to sustainable levels. This has been successfully done in a few sites where village mussel committees and mussel monitors have been appointed to control mussel harvest rates (Figure 4.64).

��#��F��#��(��Q��B��(;��(F��?��?�F(��(��Q�F��(F��?�� 243

*�"��7$�7� ?�� "� �� ?��O��)��$��;$=$�8��

Recreational shore angling has also increased enormously in popularity over the past century and by the 1990s total effort was estimated at 3,2 million angler-days per year, or approximately 1 000 angler-days fished for every km of coastline [3]. These anglers catch some 4,5 million fish per year (about 1 500 fish per km). Not surprisingly, the combined effects of such intense and sustained long-term fishing pressure, combined with a commercial fishery that targets many of the same species, has led to drastic declines in abundances of many more sought-after angling fish. Indeed, some fish populations have now been reduced to a few percent of their numbers a century ago [4]. The long-term decline in angling fish abundance and mean size is clearly evident from images of historic catches, the likes of which are hard to imagine today (Figure 4.65). Drastic reductions in catch, combined with the establishment of additional marine reserves, are necessary if angling fish stocks are to be rebuilt to anything approaching their original levels.

*�"��7$�� (�� "�� "�� '�� )'��"$� �F��Q��?��%�Q��

Commercial exploitation on rocky shores is restricted to a few high value species, notably abalone, rock lobsters and seaweeds. Abalone stocks have been severely overexploited, particularly because of a flourishing illegal fishery [5], resulting in the recent complete closure of first the recreational and then the commercial sector.


West coast rock lobster continues to sustain a valuable commercial fishery [5], although the stock has been greatly depleted over the past century. Some 9 000 recreational licenses are issued to fish Natal rock lobster each year and these fishers take about 100-150 tonnes, with a further 50 tonnes being collected by small-scale commercial fishers in the former Transkei.South African seaweeds have been commercially collected since the 1940s for extraction of alginates and agars and are used, for example, as thickeners, gelling agents, stabilisers, and emulsifiers in paints, food and cosmetics. This industry causes little ecological damage as the plants are either collected after being washed ashore or are plucked in a sustainable way that allows them to re-grow [6, 7]. Of more concern is the recent rapid increase in collection of living kelps as feed for cultured abalone, as there is insufficient kelp to meet projected future demand in some parts of the coast.

Introduction of non-native marine species

Ever since the first European explorers landed in South Africa, marine species have been continuously introduced into the region along with shipping activities. A few such species were brought in intentionally, but the vast majority arrived by accident. The mechanisms, or vectors, by which importation has taken place, have varied greatly over that time. The wooden vessels of early seafarers travelled slowly and were ideal habitats for external fouling organisms as well as specialised wood-boring species, such as shipworms and gribbles. Many early ships were also stabilised by dry ballast in the form of sand and rocks, which was loaded at the port of origin and dumped upon arrival, along with any drift-line fauna and flora that survived the journey. Modern steel vessels are much larger, more numerous and travel more rapidly. Although they are impenetrable to borers and painted with anti-fouling paint to discourage fouling organisms, they are often stabilised with ballast water. This has provided a new and different mechanism of transport for non-native species, particularly those that float or swim in the water. Modern aquaculture and the pet trade provide an additional vector for modern introductions.The first paper specifically listing introduced marine species from South Africa only appeared in 1992 and listed just 15 species [8]. By 2008, this

number had risen to 22 definite and 18 cryptogenic species (those suspected but not proven to be introduced) [9]. Ongoing research has, however, quickly increased this number and today the number of marine introductions and cryptogenic species combined stands at some 120 and continues to expand at a rate of about one species a month! Moreover is it important to recognise that even this greatly increased list represents only a subset of actual marine introductions for South Africa, as many taxa and sites remain to be studied (A. Mead unpublished data). Almost all of these species were introduced accidentally, with the exception of shellfish that have escaped from culture facilities. Most marine introductions remain restricted to sheltered harbours and estuaries, probably because conditions there most closely resemble those in their areas of origin. There are several species that are able to colonise the open wave-swept coast, with those that do so becoming very abundant (Figure 4.66).

*�"��7$�� /�� 9��'�� >�� "�� !� �� ?��>��!$��;$=$�8��

��#��F��#��(��Q��B��(;��(F��?��?�F(��(��Q�F��(F��?�� 245

Studies into the significant ecological and economic impacts of South African marine introductions are only evident for a few species, with the potential impacts of the vast majority of introductions remaining unknown [9]. The transparent sea squirt (Ciona intestinalis) causes economic damage by growing over and smothering farmed mussels [10]. The European shore crab (Carcinus maenas) is a voracious predator currently common only in harbours, but would probably decimate shellfish stocks if it spreads to sheltered bays, like Saldanha Bay [10]. The Pacific barnacle (Balanus glandula) has become the dominant barnacle along much of the west coast, displacing some intertidal species, but providing habitat for others [11]. The most significant introduction to date is the Mediterranean mussel (Mytilus galloprovincialis), which is now the most abundant species on rocky shores along the entire west and south coasts [10]. It has numerous ecological impacts: greatly increasing intertidal biomass, providing habitat for many small invertebrates, displacing large limpets and providing additional food resources for predatory species like Oystercatchers. It also forms the basis of a significant aquaculture industry.

Climate change

The impacts of global warming on the coast include rise in sea level and changes in the distributional ranges of species. Increasing sea level is not of great consequence to most coastal species, as they can simply move higher up on the shore. An exception might occur in KwaZulu-Natal, where many shores are sandy above, with rock platforms only on the lower shore. Here, rising sea levels could push some upper intertidal species completely off the rock! Of more importance are changes in the geographic ranges of species associated with changing sea temperature. For example, increased temperatures in KwaZulu-Natal might result in an expansion of coral reef habitats, which at present only just extend into the country. Surprisingly however, recent evidence suggests that coastal water temperatures are declining along much of the country (Figure 4.67). This is a result of the unique dynamic upwelling system being influenced by shifts in wind and rainfall patterns, a well known effect of climate change.

*�"��7$�4� =��")�� "�� %� �� QFF��7�� $��"� �� ;�� $!� �#�� ?�� F�� "�� #��%�B��;��

This is supported by field evidence comparing rocky shore biota in 1986 and 2007. The study site, False Bay, is located in the transition zone between the cold- and warm-temperate marine provinces of South Africa. These data, and supporting photographic evidence, show that a warm water species, the brown mussel (Perna perna), has declined in density and has actually disappeared from many sites altogether, while populations of cold water kelps have increased enormously over the same period (Figure 4.68).


*�"��7$�5� 9��"�� *�� /�� +,� �� "� ��%��""�� "��")��$��;$=$�8��

Habitat modification, pollution and disturbance

In some countries, like the Netherlands, stretches of coastline have been completely relocated by enormous seawalls or dykes. Nothing of this scale has taken place in South Africa, although the construction of harbours, marinas, seawalls, railway lines and other structures on the seashore in cities such as Cape Town [5] will have displaced some animals. These effects are, however, limited to small areas.Similarly, pipelines discharge increasing volumes of sewage, fish waste or industrial effluent into the sea, but are concentrated around a few major harbours and estuaries [5], leaving most of the coast unaffected. Disturbance, by walking or driving along the shore, diving, approaching whales too closely, feeding sharks [12] or simply disturbing nesting birds, can all affect the behaviour of target species or even cause mortality in delicate corals or birds. The recent ban of driving on beaches has had a significant effect in reducing these impacts.

Conclusion

Rocky shores have been most severely impacted by the direct exploitation of species such as abalone, rock-lobsters, mussels and coastal fishes, many of which have been reduced to a small fraction of their former numbers. The removal of such abundant species must also have had dramatic effects on the structure of the ecosystem, but these indirect effects have not been adequately studied. Introductions of non-native species have also had important effects, these being most evident on the west coast. Climate change might result in more tropical species extending into KwaZulu-Natal, but in the Cape has in fact resulted in a cooling of coastal waters, which has displaced a warmer water species and expanded the range of cooler-water forms. The effects of habitat modification, pollution and disturbance are restricted to a few sites and particularly vulnerable species, such as seabirds that nest along the coast.

��#��F��#��(��Q��B��(;��(F��?��?�F(��(��Q�F��(F��?�� 247


SeabirdsSentinels of southern Africa’s seas

Fx~V\j�w$?$�;\`|�x\X 9VjV\�8$�Ff`W

Seabirds, which feed near the top of marine food chains, are valuable indicators of changes occurring at lower trophic levels, driven by factors such as fishing and environmental change. Seabirds also are influenced by direct exploitation, habitat degradation, pollution, disease and by-catch mortality. Over the past century there have been large changes in the abundance and distribution of seabirds in South Africa. This was initially due to exploitation but more recently because of factors operating at sea, including reduced availability of food. Although competition with fisheries is a significant issue, eastward range expansions by several seabirds, including species that do not feed on fished prey, suggest that a changing environment is responsible for some recent changes in marine systems.

Introduction

Seabirds breed on land but feed at sea – attributes that make them both readily accessible for study and valuable monitors of the health of marine environments. Seabirds are wide-ranging predators in marine systems and changes in seabird populations reflect changes lower down the marine food webs. By monitoring trends in seabird parameters, the health of marine systems may be tracked, and the effects of fisheries, marine pollution and global change detected. Seabirds may truly be regarded as sentinels of the seas.Seabirds breed around the southern African coastline, mainly at predator-free islands, cliffs and at artificially-constructed guano platforms. To the north of southern Africa are long stretches of coastline devoid of suitable breeding habitat, so southern Africa’s seabirds are isolated and show a high degree of endemism. Of the fifteen seabirds that breed in southern Africa, seven

species and two subspecies are endemic to the region and breed nowhere else. The Benguela upwelling ecosystem along southern Africa’s southwestern seaboard provides rich feeding grounds for seabirds. Large aggregations of penguins, gannets and cormorants rely on this region, which also attracts a wide diversity of non-breeding visitors, mainly from sub-Antarctic and Palearctic environments. Farther south, South Africa’s Prince Edward Islands provide a breeding platform for massive congregations of seabirds, including four penguin species, five albatrosses and fourteen petrels.The large diversity of seabirds, with ranges varying from local to global, adds to their value as indicators of environmental health. However, the news is not good. Several species have shown precipitous decreases in abundance and seabirds have become one of southern Africa’s most threatened groups of marine organisms. Nine of the 15 species that breed on the mainland and 12 of the 16 that nest above ground at the Prince Edward Islands are classified as Threatened or Near Threatened.Some of the threats facing seabirds are addressed in the following subsections. The examples emphasise the value of seabirds as indicators of their environment. Monitoring of numbers of seabirds breeding and their diet since the 1950s provides one of the few windows into how southern Africa’s offshore marine systems have changed over the last half century, independent of fish catches. More sensitive indicators of seabird health are now available, including estimates of survival, breeding success, body condition and foraging effort. Together, these tools make seabirds ideal indicators of the health of marine ecosystems.

Early overexploitation

Most seabirds breed on offshore islands to avoid terrestrial predators, including humans. As seafaring skills developed, people started to visit breeding islands to collect seabird eggs, chicks and adults. Off southern Africa, seabirds were extirpated from Robben Island within a century of the formation of the Dutch colony, largely due to direct exploitation. The discovery of guano as a valuable fertiliser in the 19th century led to a wild scramble to mine accumulated deposits of the ‘white gold’, with massive impacts on seabird breeding populations (Figure 4.69). However, the value of guano also helped


to protect breeding species from the worst excesses of direct exploitation. Only African penguins, whose eggs were collected in vast numbers, were hard hit. During the early 20th century up to 300 000 eggs were taken from Dassen Island each year, causing the population there to collapse from several million birds at the start of the century to only 72 500 pairs by the 1950s. Non-breeding seabirds also were affected, with fishers catching thousands of albatrosses and petrels at sea for food. Fortunately, seabirds are now protected throughout the region, and these practices have largely ceased.

*�"��7$�3� �� %��"��%�� $��F$w$?$�;��

The by-catch issue

Large numbers of seabirds are killed accidentally when they become entangled in fishing gear and drown. High-seas drift nets are especially problematic and have been banned worldwide, but unacceptably large numbers of birds are killed when they are hooked on long-lines or tangled in trawl gear [1]. Species that scavenge from ships, including albatrosses and some petrels, are most susceptible to this form of mortality (Figure 4.70).For most fisheries, a simple suite of preventative measures can greatly reduce by-catch of seabirds. Considerable effort has been taken to ensure these measures are implemented effectively by fisheries throughout southern Africa, and as a result the numbers of birds killed have fallen – but there remains room for further improvement.

*�"��7$4,� Q�� ")�� $��9$8$�F��

Marine pollution

Seabirds, especially African penguins, which do not fly, have been adversely affected by oil pollution (Figure 4.71). In 2000, following the sinking of the Treasure, almost 20 000 African penguins were oiled off South Africa and caught for rehabilitation. About 20 000 more were relocated to unpolluted seas to prevent their becoming oiled. More than 3 000 chicks, orphaned through the capture of their parents, were caught for captive rearing. In terms of numbers of live animals handled, the rescue operation was perhaps the largest yet achieved.

��#��F��#��(��Q��B��(;��(F��?��?�F(��(��Q�F��(F��?�� 249

*�"��7$4-� ��"��$��=$8$�B��

Oil is not the only pollution issue. Marine litter entangles seabirds and small plastic items are eaten by seabirds. Virtually all great shearwaters and blue petrels sampled off southern Africa contain some plastic in their stomachs. Ingested plastic is retained for weeks or months, reducing the effective stomach volume of seabirds and sometimes blocking their digestive tract. Other threats include persistent organic pollutants and heavy metals, which become concentrated in top predators.

Competition with fishing

Several of southern Africa’s seabirds eat prey species that are the targets of commercial fisheries. For example, anchovy and sardine caught by purse-seine fleets are also the main forage food of African penguins, Cape gannets and Cape cormorants. Following huge catches of sardine off Namibia in the 1960s, that resource collapsed and fishing precluded its replacement by

anchovy (Figure 4.72). Subsequently, the numbers of African penguins, Cape gannets and Cape cormorants breeding in Namibia decreased by 90%, 95% and 62%, respectively. As sardine decreased, its range contracted to the north of Namibia, away from island colonies of penguins and gannets centred near Lüderitz. Cape cormorants breeding at guano platforms in central Namibia were able to exploit the decreasing sardine for longer than the penguins and gannets and decreased after these two species.More recently, fishing pressure concentrated off South Africa’s west coast has exacerbated the influence of an eastward shift in the distributions of anchovy and sardine to the Agulhas Bank. This has led to a severe mismatch in the distributions of the breeding localities and prey of predators, with resultant large decreases in numbers of breeding seabirds. Breeding success of seabirds decreased as parents worked harder to find food [3] or switched from high-quality prey to low-quality trawler discards [4], and adult mortality increased [5]. For species with limited foraging ranges, such as African penguins, the impacts were severe, with their populations at islands off the west coast decreasing by 70% between 2004 and 2009.

*�"��7$4+� ��"��"��%�;��"��;��+�$�� %�� '��)��$��F�� "�� /�� ?��%� � #�$� ��"��)8��$�$�+,,4�


*�"��7$46� F�� "� �� !� �� "��Q��"��$��F��8��

*�"��7$47� ��"��9��(��!��!��"��%�-337:3�)+,,4:,5$�?��°�-��#��$��F��(�;��9��!�=��4�

Climate change

There is increasing evidence that climate change impacts the conservation status of southern African seabirds, including altering the abundance or the distribution of their prey. In the case of seabirds that feed on fish targeted by commercial fisheries, it is hard to disentangle the effects of fishing pressure and climate change. For example, climate change is thought to be at least partly responsible for the recent eastward shift in the distribution of epipelagic fish off South Africa. But for other species, global change effects offer the most plausible explanation for changes in their distributions and abundance. For example, crowned cormorants and Hartlaub’s gulls, which do not feed on commercially-exploited prey, have extended their range to the east (Figure 4.73). Bank cormorant numbers have collapsed along much of the west coast following decreases in their prey. However, their numbers have increased in the south of their range, following increases in rock lobster populations in the same region.Farther south, southern rockhopper penguins leave the Prince Edward Islands for six months each year. The weights of adults returning to breed have decreased markedly in recent seasons, suggesting a reduced availability of food at overwintering feeding grounds (Figure 4.74). This has resulted in a poorer breeding success and a large decrease in the number of rockhopper penguins, despite only limited human activities in this remote region.

Predation and disease

Seabird populations struggling to cope with human-induced changes are further stressed by increases in natural predators and the frequency of disease outbreaks. Recovery of Cape fur seal numbers following exploitation has resulted in many more seabirds being eaten by seals. At Malgas Island, more than half the gannet chicks produced are killed by seals shortly after they leave the island. In 2005, a few young bull seals from the burgeoning seal population at Bird Island, Lambert’s Bay, entered the gannet colony to catch adult birds, causing the entire colony to be deserted. Only drastic intervention allowed the colony to be re-established. A large increase in the population of white pelicans has impacted seabirds breeding on Dassen Island and at colonies around Saldanha Bay, with pelicans eating large proportions

��#��F��#��(��Q��B��(;��(F��?��?�F(��(��Q�F��(F��?�� 251

of cormorant and gull chicks at these islands. At the same time, repeated outbreaks of avian cholera have killed seabirds, especially Cape cormorants.

Resilience to change

Seabirds vary in their ability to respond to changing environments. Many species can change their diet and increase their foraging effort to compensate for reduced availability of food, but there are limits to this flexibility [8]. Seabirds typically are long-lived species with high adult survival. When times are tough, they first reduce their investment in reproduction before compromising their survival. However, many species exhibit strong fidelity to breeding sites, especially once they are established breeders. This reduces their ability to respond to large-scale changes in the distribution of their prey. Despite this limitation, there have been long-term trans-boundary shifts in the distributions of some seabirds. For example, 80% of Cape gannets bred in Namibia in 1956/57, whereas 93% of the population was in South Africa in 2005/06. This switch in regional distribution over 50 years closely tracked regional trends in the abundance of epipelagic fish (Figure 4.75). However, such regional changes in distribution depend on the availability of alternative breeding sites in areas with sufficient food for breeding populations. Seabirds will struggle to track the recent shift in epipelagic fish to the south coast of South Africa because there are no breeding islands between Cape Agulhas and Port Elizabeth. The trans-boundary shifts emphasise the need for regional co-operation in the conservation of southern Africa’s seabirds.

*�"��7$4�� !�;��"��!��"��'�� !� �� %�-3��:�4)+,,�:,�$� �F�� *�"��7� �� 3�%��B��9��%��



Causes and effects of changes in the distribution of anchovy

and sardine in shelf waters off South Africa

;`\}�#$��`W�XV\�=^W�VW w`WVj�;$�;xVj�VV

=`{\VW�V�*$�Q{j�z^W�k

Anchovy and sardine support South Africa’s largest commercial fishery and are also the major prey of a wide variety of fish, seabirds and marine mammals. Both of these economically and ecologically important species have shifted eastwards in recent years − anchovy abruptly and sardine more gradually. Synchronous changes in the environment suggest that the anchovy shift was environmentally mediated, whereas the sardine shift may have been environmentally mediated and/or driven by anthropogenic forcing through fishing. These changed distribution patterns have had significant negative ramifications both for the fishery, and also for the ecosystem as a whole.

Introduction

South Africa’s small pelagic fishery that targets anchovy (Engraulis encrasicolus) and sardine (Sardinops sagax) is the country’s largest in terms of landed mass, with annual average catches of around 400 000 tonnes taken over the past six decades [1]. Purse-seine vessels (Figure 4.76a) are used to catch the fish, with anchovy being caught predominantly inshore off the west coast, whereas sardine are caught farther offshore and along both the west and south coasts (Figure 4.76b). Anchovy are processed in industrial factories to fishmeal and oil, whilst sardine are canned or frozen for human consumption, pet food or bait, or processed to fishmeal. The small pelagic sector employs over

*�"��7$4�� !� �� "�� )�� "�"�� '��"$� �� *��"�8�� !� ��8(�� "� �� -,��±�-,��!��-354)+,,�$��>�� "��>�%�� "�� $��F��(�;��9��!�=��+�

��!

�!

��#��F��#��(��Q��B��(;��(F��?��?�F(��(��Q�F��(F��?�� 253

10 000 people and supports around 100 purse-seine vessels, eight fishmeal plants, six canning factories and over 40 bait-packing facilities [2]. In addition to their economic importance, anchovy and sardine are also of considerable ecological importance as they are the principal prey of many fish, marine mammal and seabird species [3]. Since 1983, annual surveys have been used to assess changes in the abundance and distribution patterns of both anchovy and sardine [4]. In recent years both species have shown an eastward shift in their distributions − anchovy abruptly and sardine more gradually. These shifts have had a serious impact on the South African small pelagic fishery, particularly the sardine fishery, and also on the functioning of the coastal pelagic ecosystem off the west coast. This chapter describes the hypothesised causes of these shifts and their attendant consequences.

Anchovy

Adult anchovy have shifted their distribution eastward over the past two and a half decades, from being located predominantly to the west of Cape Agulhas during the early part of the time-series to being predominantly to the east of Cape Agulhas [5] (Figure 4.77). This shift occurred abruptly in 1996 when the anchovy adult population was at its lowest recorded level and has persisted since, with two-thirds (on average) of anchovy adults observed to the east of Cape Agulhas during subsequent surveys. In order to assess whether the anchovy shift was environmentally mediated, an analysis of monthly sea surface temperature (SST) data from four sub-regions of the Agulhas Bank (Figure 4.78a) collected over the last 25 years was conducted.That analysis revealed a shift in the environment that occurred in 1996 and has persisted since. This shift appeared as a sudden cooling of the surface water in the coastal region relative to the central mid-shelf part of the Bank and resulted in an increased cross-shelf SST gradient between coastal and mid-shelf waters. Although there was a gradual increase in SST gradient on the western Agulhas Bank (WAB) coastal region (Figure 4.78b), surface cooling was limited to the coastal domain east of Cape Agulhas (Figures 4.78c and d). Time series of other environmental data in the Agulhas Bank region, including surface atmospheric pressure and wind stress, also show a mid-1990s shift, but are not described here. That the observed shift in

cross-shelf SST gradient occurred at the same time as anchovy adults shifted their distribution suggests that the anchovy shift was linked to changes in the environment. This is supported by the positive relationship between cross-shelf SST gradient over the central Agulhas Bank and the percentage of the anchovy adult biomass that was located to the east of Cape Agulhas (not shown). The cooling of the coastal domain to the east of Cape Agulhas was considered to be due to increased coastal upwelling, which would have resulted in enhanced productivity and improved feeding conditions for anchovy adults in that region compared to west of Cape Agulhas. Hence, environmentally driven changes in food availability appear to be responsible for the anchovy eastward shift [5].

*�"��7$44� 9��"��;��"��"��#��%�-357)+,,5%��"��"�� ;��"��-33��$��B��

��!

�!

��!

��!

*�"��7$45� ��!�=�� )��"��/;�²��"��/��%�;�/;�²��"��/��%�;�/��²��"��/��%��/;�²��"��/��!��"��/�� )��$��)�!� ?�� !� �� "�� "�� /�� ;�/�!� �� )��"�� /;%� ;�/;� �� /;!� ��-35-��#��+,,�$�#��"��-35�)-33��-33�)+,,�!��)��"��$��F��(�;��9��!=��

*�"��7$43� �� "� �� %� ��"� �� )�� "�� "�� /�� #��!� �� -35+)+,,��"��!%�� "� �� -356%� -355� �� -335$� �� $��F��(�;��9��!�=��

254

��#��F��#��(��Q��B��(;��(F��?��?�F(��(��Q�F��(F��?�� 255

Figure 4.79 illustrates the impact of environmental conditions on anchovy distribution patterns and shows the observed distribution of anchovy adults in 1988 (a year of reduced cross-shelf SST gradient) and in 1998 (a year of increased cross-shelf SST gradient). It also shows the distribution of anchovy adults during 1983. In that year most of the anchovy biomass was observed to the east of Cape Agulhas, and a high cross-shelf SST gradient over the central Agulhas Bank (CAB), which was similar in magnitude to values observed from 1996 onwards, was also seen. These results show how small pelagic fish may respond to climate variability and could prove useful in scenario-building in order to assess possible impacts of global climate change. The anchovy eastward shift is unlikely to have serious impacts on the fishery, given that most anchovy are caught as juvenile fish (approximately six months old) off the west coast, and recruitment by anchovy to the west coast appears unaffected by the eastward shift. From an ecological perspective, however, the implications are likely to be more significant, in particular the impacts of reduced prey availability for predators off South Africa’s west coast, for example, the Cape gannet [6] and African penguin [7].

Sardine

Sardine, too, have shown a substantial eastward shift in their distribution (Figure 4.80), although this occurred gradually and not abruptly as is the case for anchovy. The area to the west of Cape Agulhas contained the bulk of the sardine biomass during the early 1980s and early 1990s [4], with most of the sardine population being located on the western Agulhas Bank (WAB) for the rest of the 1990s. In the late 1990s, however, sardine biomass east of Cape Agulhas exceeded that to the west, and this pattern has persisted since [8]. This gradual change in sardine distribution has been accompanied by episodic changes in the location of sardine spawning, with shifts between predominantly west coast spawning (to the west of Cape Agulhas) and predominantly south coast spawning (to the east of Cape Agulhas) being observed [1].

*�"��7$5,� 9��"�� ;�� "�� "� �� #��%�-357)+,,5%��"��"�� ;��"��-334��+,,��+,,5$��B��5��

The changed sardine distribution has resulted in a significant spatial mismatch between fishing effort and sardine abundance over the past decade. The sardine fishery developed on the west coast during the 1940s and fishing effort and processing capacity there increased rapidly. At present, almost all processing infrastructure is situated on the west coast in the vicinity of St Helena Bay (Figure 4.76), yet the centre of gravity (CoG; essentially the weighted average location) of sardine catches has shifted successively further east each year since 1997 (Figure 4.81), arising from both a decline in catches made off the west coast and an increase in catches made off the south coast. This spatial mismatch between the localities of sardine capture and sardine processing facilities has resulted in increased costs to the pelagic fishery, which is a significant problem in a relatively large volume/low profit fishery such as this. For example, during the early and mid-2000s, before the establishment of a sardine processing facility on the south coast at Mossel Bay (see Figure 4.76), a considerable proportion of sardine caught on the south coast was landed at Mossel Bay and then transported by road to the west coast processing plants.


*�"��7$5-� =�� "�� ;�8!��"�� -354)+,,�$� ��>�� %��>�� $��F��(�;��9��!�=��3�

Several hypotheses to explain the change in sardine distribution from the WAB to the CAB and EAB have been proposed [8], including: local depletion of sardine off the west coast and WAB following higher levels of exploitation in the west than in the east; environmentally induced changes in adult sardine distribution; and the possibility that juvenile sardine that came from successful south coast spawning contributed disproportionately more towards sardine recruitment, with fish spawned off the south coast dominating the population and exhibiting natal homing (fish returning to spawn in the same area that they themselves were spawned). Calculation of sardine exploitation levels east and west of Cape Agulhas, namely, the total annual catch from that area as a percentage of the biomass in that area observed during the survey conducted in the preceding summer, provide support for the first hypothesis, as the difference in exploitation between the two areas is striking (Figure 4.82). In addition, the sardine eastward shift was accompanied by poor recruitment success from 2003 to 2008, with a subsequent sharp decline in the sardine biomass from more than 4,5 million tonnes in 2002 to less than 400 000 tonnes in 2008. That the sardine eastward shift was followed by poor recruitment whilst the anchovy shift was not indicates differences between the anchovy and sardine early life histories, which are not clearly understood.

*�"��7$5+� �� ;�� "��%� -354)+,,5$��B��5��

Clear evidence of an environmental trigger that may have initiated the sardine shift has not yet been found, although this does not preclude environmental variability as a driver of the changed sardine distribution. In 2007 and 2008, substantial numbers of sardine eggs were observed to the west of Cape Agulhas, suggesting a shift back to west coast spawning following a six-year period of south coast spawning. Additionally, during the 2008 survey over half of the sardine biomass was observed to the west of Cape Agulhas (Figure 4.80). The alternation between west and south coast spawning, and the move by sardine back to the west coast in 2008, may arise from sardine tracking environmental variability and moving to that part of the coast that provides the most favourable environmental conditions. Alternatively, these changes could be driven by subpopulation-specific life-cycle strategies, such as the natal homing described previously.The sardine eastward shift has had serious ecological consequences in addition to the negative impacts felt by the fishery, chief amongst these being the negative impacts on predators off the west coast. For example, Cape gannets breeding on Malgas Island off the west coast now feed primarily on hake discards from demersal trawling operations [6] and not on their normal sardine and anchovy prey. The lower energetic content of hake compared to pelagic fish has resulted in reduced breeding success and a declining gannet population at that colony.

��#��F��#��(��Q��B��(;��(F��?��?�F(��(��Q�F��(F��?�� 257

Conclusions

Populations of both anchovy and sardine have shown eastward shifts in their distributions in recent years, with attendant negative impacts on the fishery (sardine) and ecosystem functioning (both species) off the west coast. The anchovy shift has been attributed to environmental variability, whilst anthropogenic forcing through fishing, environmental variability, or a combination of the two mechanisms could have caused the sardine shift. An improved understanding of how these populations respond to environmental variation, and in particular how they are likely to respond to climate change, will enable pre-emptive management measures to be taken in order to preserve the status of these fish populations, their functioning in the ecosystem and the predators that feed upon them.

Acknowledgements

We wish to thank Cathy Boucher (Department of Agriculture, Forestry and Fisheries) for redrawing and standardising the illustrations, and to Tracey Fairweather (Department of Agriculture, Forestry and Fisheries) for her assistance with Figure 4.76b.


Large-scale shifts in the spatial distribution of

West Coast rock lobster in South Africa

�WX\V|�;$�;x�_�\x�j

A major shift in the distribution of West Coast rock lobster (Jasus lalandii) from the traditional fishing grounds on the west coast to the more southern fishing grounds was observed between the late 1980s, early 1990s and at the turn of the century. The early 1990s was also the start of a major influx of lobsters into the area east of Cape Hangklip, an area not previously associated with high lobster abundance. The ecological, fisheries and resource management implications of these shifts have been severe and are likely to cause challenges in the future management of both rock lobster and abalone (Haliotis midae) resources. The temporal coincidence of the shifts in lobster distribution with events such as the onset of reduced somatic growth and increased lobster walkouts suggests a linkage in the underlying environmental causes or forcing factors, as do congruent changes in other components of South Africa’s Western Cape marine ecosystems.

Introduction

West Coast rock lobster, Jasus lalandii, are distributed generally close to shore from just north of Walvis Bay in Namibia, to near East London in South Africa. Commercial densities are, however, restricted to the west coast from around Swakopmund in Namibia to slightly east of Cape Hangklip in South Africa. While the earliest records of human exploitation date back some 10 000 years, commercial exploitation commenced in the late nineteenth century and expanded during the early twentieth century. The commercial fishery is currently managed through a Total Allowable Catch (TAC),


minimum size limits, closed seasons and defined fishing zones and areas [1]. The fishery is valued in excess of R260 million (approximately US$40 million) per annum and provides employment for some 4 000 people. Traditionally, the lobster fishery was of particular importance to communities on the South African west coast who relied heavily on the seasonal employment provided. This species also supports an active recreational fishery, which is governed by an annual permit requirement, a minimum size limit, closed seasons, gear restrictions and closed areas. The commercial fishery is currently divided into distinct nearshore and offshore components, with the split in TAC between these components being based on resource availability.

Changing geographical distribution

A clear shift in regional resource availability is evident when examining the commercial catches made in the various fishing zones since the late 1960s [2]. The lobster resource, based on the biological considerations such as the timing of the moult and reproductive cycles, can be divided into two broad regions: a typical west coast environment (Orange River to just north of Dassen Island) and the more southern component of the fishery (from around Hout Bay to Gansbaai). The fishing area around Dassen Island separates these regions (Figure 4.83). The relative contribution of these regions to the overall annual commercial landings (Figure 4.84) clearly illustrates a major shift in spatial resource availability between the late 1980s/early 1990s and the turn of the century, the start of a period of relative stability. Over that period the contribution of the west coast region to total lobster landings declined from about 60% to less than 10%, whereas that of the southern region increased from around 18% to around 60%. The relative contribution of the Dassen Island area declined slightly during the 1990s but increased to around 30%. This area has remained stable at that level since 2000.

*�"��7$56� ?��"��%�#��(��'��"��"��$

*�"��7$57� 9��"�� %� #�� (�� ;��"�$��'��$��F��(�;��9��!�=��+�

��#��F��#��(��Q��B��(;��(F��?��?�F(��(��Q�F��(F��?�� 259

The period between the late 1980s/early 1990s through to the end of the century was also marked by a sharp decline in lobster somatic growth rates [3] and a major increase in the number and severity of lobster ‘walkouts’ in the Elands Bay region (Figure 4.85) [4]. The decline in the contribution of the west coast region to total lobster landings during the 1990s is most likely a combination of reduced somatic growth rates, the loss of a considerable biomass during lobster walkouts and the slow rate of resource recovery in these areas since then, rather than a significant increase in lobster abundance in the southern grounds.

*�"��7$5�� $��+,,,�� ?��+,,5$��+�

Implications of regional shift

This change in resource distribution has had major implications for the lobster fishery and the fishing community. The lobster fishery on the west coast is now almost exclusively (>99%) a nearshore hoopnet fishery. The loss of jobs in lobster processing facilities, coupled with the reduced numbers of long-term rights that could be allocated in these areas to ensure resource

sustainability, has resulted in substantial economic hardship for the west coast communities. This has been exacerbated by the job losses associated with an eastward shift in the pelagic resources [5]. While the highly dynamic nature of the west coast environment makes the assessment of any ecosystem effects of this resource shift difficult to identify, the decrease in lobster along the west coast has had a significant impact on the number of breeding pairs of Bank cormorants, Phalacrocorax neglectus, on islands along the west coast [6]. This species has a high proportion of lobster in their diet.The large-scale shift in lobster commercial catch distribution was accompanied by a marked influx of lobsters into the area east of Cape Hangklip (EOCH), an area that has been the mainstay of a lucrative fishery for South African abalone, Haliotis midae, since 1949. The numbers of West Coast rock lobster in the nearshore (<30m) regions EOCH prior to the 1990s were negligible [7]. Observations of an increase in the abundance of lobster in this area were first noted during abalone recruitment surveys conducted in the early 1990s [8]. These observations were corroborated by recreational fishery catch data over that period and confirmed and quantified by a number of directed field surveys (mostly hoopnet and diving) during the period 1996 to 1999 [9]. As juvenile abalone derive protection from predation by actively sheltering under sea urchin spines, the presence of urchins is considered important to the successful recruitment of juvenile abalone to the commercial fishery. The influx of lobster, a key benthic predator, has had a profound effect on the benthic ecology of the area EOCH, the most obvious being the virtual disappearance of sea urchins (Figure 4.86) and the winkle, Turbo cidaris, as well as a major increase in foliar algal abundance [9]. The decrease in abalone recruitment, together with rampant illegal harvesting, has had a severe impact on the commercial and recreational fisheries for abalone. The recreational fishery for this species was suspended in 2003 and two formally productive abalone zones were closed to commercial harvesting in 2006. The increased lobster abundance in the area EOCH did, however, result in the introduction of a commercial lobster fishery in that area in 2001/2002. A continuation of the eastward movement of lobster is not supported by the lobster commercial fishery data from the area EOCH or the results of directed inshore Fisheries Monitoring Surveys conducted both in that area and to the west of Danger Point.


*�"��7$5�� !��:��;��Q��"��$��F$��!��"��$��$�;��

Causes

Adult lobsters do not undertake distinct longshore migrations, but do undergo a well-defined seasonal migration towards and away from shore. The hypothesis that an onshore movement from deeper waters was the most likely source of the lobsters moving into EOCH is supported by the size composition (mainly adults) of lobsters observed during the early phase of the influx. Settlement of post-larval lobsters into the area only became a regular event after a substantial adult population had been established. Whereas the mechanism of the lobster influx can be argued with some confidence, the underlying reason why this happened is unclear. The hypothesis that the habitat EOCH became favourable to lobster occupation in the early 1990s is difficult to quantify given the paucity of long-term environmental data in the nearshore areas EOCH. The obvious success of the lobster moving into the area, indicated by good somatic growth, enhanced reproduction and successful post-larval recruitment, negates the theory that the lobster were forced into a suboptimal habitat by intraspecific competition or any other factor.

Conclusions

The temporal coincidence of the shift in lobster distribution with a coastwide decrease in somatic growth rates and a major increase in the number and severity of low-oxygen induced walkouts suggests some linkage in the underlying environmental cause, but this remains poorly understood. Whereas these events have not occurred in isolation (the 1990s being a period of an eastward shift in pelagic resources), the linkage between the changes in the pelagic and benthic systems, if any, remains unknown. The ecological, fisheries and resource management implications of these shifts in distribution of the West Coast rock lobster resource have been severe. However, the question whether these shifts are permanent, or part of some decadal/multidecadal cycle, remains unanswered. The impacts of these changes are likely to cause further major challenges in the future management of both the rock lobster and abalone resources.

��!

�!

?��9��?��;�� £��

263


Introductionwxz`WW�F$�$�={j�Vz`\qk

In essence, climate change is nothing new. The climate system of the world has been changing on temporal scales of decades, millennia and millions of years. However, natural processes, some of which we still do not understand, have driven previous climate change.By contrast, current climate change may be largely human driven and may be happening at a rate not recorded in the accessible history of changes of the planet. This rapid change carries potentially huge and previously unknown risks, since ecosystems, both on land and in the sea, may not be able to adjust swiftly enough to ensure survival. But this threat also holds for human society. Sea level may, for instance, start to rise more rapidly than coastal communities can cope with and towns and parts of the coastline may well have to be abandoned. This scenario is not too imaginary or far-fetched. In Britain, policy makers have already decided that, on a cost-benefit ratio, certain habitations near the coast where coastal erosion is very severe will have to be abandoned. It is just too expensive to put structures in place to prevent future erosion in order to save only a few properties. But how does this threatening climate work?The climate system of the planet consists of a large number of strongly linked and interactive systems including the atmosphere, the ocean, the cryosphere (all ice, such as the cover of the poles), the hydrosphere on land and the biosphere (consisting of all ecosystems, both terrestrial and marine). The complex linkages and interplay between these is not perfectly understood. Huge numerical models on supercomputers are attempting to unravel some of these intricate relationships, but this has only just started.

Of all the different global components of climate, the oceanic component is one of the least understood. No long records of changes are available for this part of the system. Furthermore, numerous regions of the ocean are relatively inaccessible and underexplored. There are many automated systems currently observing the ocean internally and from space and gradually this ignorance of the oceans will be whittled away. However, this process will take a long time.Why is knowledge of the ocean important in order to understand global climate change and how it affects southern Africa? Southern Africa forms a small wedge of land sticking into the vast ocean region consisting of the South Atlantic, the South Indian and the Southern Ocean. We can, therefore, confidently expect that the ocean environment will play a definitive role in the climate – and climate change − of the subcontinent.The chapters that follow provide a glimpse of the oceanic changes and some of their impacts.

=�*�� (��"�� $�?��>%�+,,,%�� (��)�%�8��;��9��@��



The southern African oceanswxz`WW�F$�$�={j�Vz`\qk

Climate is controlled by the atmosphere and by the oceans. Of these two, the ocean is the least understood. South Africa is located at the junction of the Southern, Indian and Atlantic Oceans, with each of these oceans having its own unique flow characteristics. The processes that occur in these oceans not only influence the climate of southern Africa, but have an effect on global climate as well. Records of sea surface temperatures and sea level height show that these oceans are already reacting to climatic changes. In order to properly prepare for the impact of climate change, we need to substantially increase our knowledge of the ocean processes around South Africa.

Introduction

A number of factors influence global climate, with arguably the most important of these being the circulation of the atmosphere and that of the ocean. These two circulation systems are inextricably linked. The global atmospheric systems are large, move rapidly and carry comparatively little heat. By contrast, oceanic systems, such as currents and eddies, or ocean vortices, have smaller dimensions and move slower, but carry enormous amounts of heat. It is this heat contents of the covering of the planet that has the greatest immediate impact on regional climate. It is, therefore, clear that studying one circulation system to the exclusion of the other will severely limit our ability to understand climate and climate change.The atmosphere is readily available for observation, and as such, this system has seen the most and the most durable set of observations. By contrast, the ocean is logistically difficult to get at. To date, most observations of the ocean have been done using either commercial or research vessels. Commercial vessels ply set routes between harbours and so do not present good geographic coverage. On the other hand, research vessels, which are very expensive, tend to go to specifically-targeted regions where we think we can learn important

things about the ocean. The advent of satellite remote sensing in the 1970s has made an enormous difference to our ocean observation efforts. Regular coverage of the global ocean to observe sea surface temperatures has been followed by similar observations of ocean colour. However, even these revolutionary changes to ocean observations have their distinct limitations. Satellite remote sensors only observe the sea surface whereas the ocean is about 4 000 m deep on average. But the use of profiling floats is helping to overcome this limitation. Profiling floats are instrumented buoys that can dive to great depths, making measurements en route. They then return to the sea surface and telemeter this information to the interested parties by satellites. These floats are indispensible in oceanography and give to the science what meteorologist have had for decades in radiosondes, which are used to profile the atmosphere. These are significant developments in the monitoring of the ocean, but the records we have gained so far are of very short duration. Let’s now find out more about the ocean circulation near southern Africa.

The ocean circulation around southern Africa

South Africa lies at the intersection of three major oceans: the Indian Ocean to the east, the Atlantic Ocean to the west and the Southern Ocean to the south. Each of these oceans has its own characteristic ocean circulation and in the region south of the continent these circulations interact in a dynamic and important way.The circulation in the South-West Indian Ocean is typical of that of a subtropical ocean basin. The prevailing winds drive the waters in an anti-clockwise gyre that extends all the way from Africa to Australia. However, this gyre is not symmetrical, but is strongly concentrated on the western side of the ocean basin. The result of this concentration is that a major and intense current, the Agulhas Current, is found along the eastern seaboard of South Africa. This current is about 100 km wide, extends to depths of 3 000 m or more and carries about 65 million cubic metres of water per second! Water from the whole South Indian Ocean, including water from the tropics, is funnelled into the Agulhas Current. This water can be readily seen in satellite images of the sea surface temperatures and is warm compared to adjacent waters (Figure 4.87).

��#��F��#��(��Q��B��(;��(F��?��?�F(��**�Q�F��(F��?�� 265

*�"��7$54� �� "�� $� (�� "��;��!��"�� !%� �� :"��!� �� ;��"��"��!$�

On the other side of southern Africa, the main current, the Benguela Current, also forms part of the wind-driven, subtropical gyre, this time of the South Atlantic Ocean. However, the Benguela Current, lying on the eastern side of this ocean basin, is a wide, shallow and slow equatorward drift. Its waters come largely from colder climes and hence it is a cold current. This cold current should not be confused with the wind-driven, coastal upwelling that is found along the southwest coast of the subcontinent. When the dominant winds blow the waters in the surface layer of the ocean away from land, cold deeper water upwells to take its place. This upwelling water is rich in all kinds of nutrients and leads to a bloom in marine algae, called phytoplankton. It thus lays the basis for a whole ecosystem and a very productive and remunerative fishing industry.

To the south of Africa lies the vast Southern Ocean, which extends all the way to the continent of Antarctica. In this ocean the Antarctic Circumpolar Current carries water past the tip of Africa from west to east. The northern border of the Southern Ocean, which separates it from the subtropical gyres of the South Atlantic and the South Indian Oceans, is the Subtropical Convergence (vide Figure 4.87). This ocean front exhibits very high gradients in temperature and salinity from north to south. Although all the water in the Southern Ocean south of Africa moves from west to east, its direction is influenced locally by bottom ridges and other obstructions that may cause it to meander, shed eddies or avoid certain shallow regions.Directly south of Africa these three circulations interact in a dramatic fashion. The mighty Agulhas Current turns in its tracks at the Agulhas Retroflection (Figure 4.88) and flows back into the Indian Ocean as the Agulhas Return Current. In this process it sheds huge eddies, called Agulhas Rings, with diameters of up to 300 km and extending all the way to the sea floor at 4 000 m. These Rings then are carried by the Benguela Current into the centre of the South Atlantic Ocean. The impact of the Agulhas Retroflection forces the Subtropical Convergence to the south and the warm water of the Agulhas Return Current enhances the temperature gradients across the Subtropical Convergence. Apart from this interaction, these currents and ocean circulations have an impact on local weather and climate.

Climatological influence of southern African oceans

Ocean currents and water masses largely determine the weather and climate of the continents and South Africa is no exception. The warm Agulhas Current on the eastern side of the subcontinent causes KwaZulu-Natal to be warm and moist (Figure 4.89), whereas the west coast is much cooler. Furthermore, these respective ocean conditions affect the rainfall over the adjacent landmasses. Air moving over the Agulhas Current picks up heat and moisture that enhances rainfall when this water mass moves over land. Similarly, the disruption of the cold upwelling regime on the west coast by the occasional overflow of warm water from the north, the so-called Benguela Niño, has also been shown to affect local rainfall. However, adjacent seas also have a wide-ranging influence.


*�"��7$55� �� "�� "��F�� "�� -�$�F��"��$��$�� "��;�� "��F�� "�� F��;��$�;��%��!��;��$�

*�"��7$53� �� "�� )�� (��+�$�F�� )��%��"��"�� "�� $� �� "�� %��$��$

The surface temperatures of the ocean expanses are not constant. As can be expected, they show seasonal changes. They also show changes from year to year, with certain parts of the ocean surface being warmer during certain years and some parts being cooler than usual. Such changes have a definite effect on the overlying atmosphere. A wealth of research has shown how such changes may affect the rainfall over southern Africa. In addition, the current processes near southern African shores have a decided influence on global climate and climate change. The water of the Agulhas Current is warm and salty and the Agulhas Rings that are shed at the southern termination of the Agulhas Current carry enormous amounts of heat and extra salt into the

��#��F��#��(��Q��B��(;��(F��?��?�F(��**�Q�F��(F��?�� 267

South Atlantic. This heat spreads slowly over the South Atlantic to the North Atlantic, eventually influencing even the climate of Europe. Climate models have demonstrated that changes in the flow from the Agulhas Current into the South Atlantic have major effects on climate conditions in the northern hemisphere.In short, changes in the oceans around southern Africa have short-term effects on the climate of southern Africa, including rainfall, but also long-term effect on local as well as global climate. But are such changes actually occurring?

Changes in the ocean

Ocean currents around South Africa have been monitored accurately and in detail only since the 1970s when satellite monitoring became possible. It is too soon to assess long-term changes. There are, however, some intriguing signs wherever longer-term observations have been made.At Marion Island, the southernmost territory of South Africa, about 2 000 km southeast of Cape Town, sea surface temperatures have been measured on a daily basis over the past 50 years. A careful statistical analysis has shown that the temperature there has increased by 1,4 ºC over the period of observations. It has been inferred that this climatic change is not due to global warming, but is a result of changes in the ozone, also induced by human activity.Another ocean variable that has been observed on a regular basis for a long time, even in South Africa with its relatively short history, is sea level. These observations have been done because shipping needs to know about tides. However, when the tidal and other signals are removed from the record, one can notice a long-term increase in sea level of about 2 mm per year. This means that the oceans are warming up and expanding, and since the ocean basins (in which the seawater lies) are not growing, the water has to rise. Water from snow and glaciers that are melting worldwide exacerbates this rise in sea level due to ocean warming. At Marion Island, many areas that used to have snow cover year round are now free of snow.

Preventive measures or, what can be done

The exact effect of the warming of the ocean on South Africa’s weather and climate is not yet certain. That there is going to be an effect can readily be seen at Marion Island where the vegetation is changing due to climate change, where the locations of certain ecosystems are in flux and where alien species are more invasive than before.So what preventative measures can we take to counteract the effects of ocean warming? Firstly, efforts should be aimed at increasing our understanding of the changes in the ocean currents and surface temperatures that can be expected. This can be achieved with appropriate sophisticated modelling and by studying how the oceans have changed in the past. However, many of the most elementary mechanisms that play a role in the oceans’ ameliorating effect on climate change are still not perfectly understood. Without proper knowledge of the ocean systems, much of our prognostication is going to remain in the realm of speculation.Second, it is clear that where long records of regular observations have been kept, much was learned about climate changes and how the terrestrial environment reacted to such changes. Wider networks of observation locations, aimed at persistent and long-term monitoring, will be a boon to understanding how the inevitably growing effects of global climate change is going to affect South Africa.



On the recent warming of the Agulhas Current

?`jz^V{�Fx{`{}j 9^V\\^�_�9VW�VW

/VW�`q^W�9xz}

The Agulhas Current is an energetic current driven by the wind field over the Indian Ocean. It has a profound effect on the climate and the coastal ecosystem of South Africa and plays a key role in the global ocean circulation. The current carries warm and salty water from the tropics polewards and controls the exchange of heat and salt between the Indian and Atlantic Oceans. Since the 1980s, the sea surface temperature of the Agulhas Current system has increased significantly. This is due to an increase of its transport in response to an augmentation in wind stress curl in the South Indian Ocean. This causes an intensification of the Agulhas Current system and leads to an increased flux of salt and heat into the Atlantic Ocean. There is also an augmentation in the transfer of energy from the Agulhas Current to the atmosphere due to increased evaporation. These observed changes could have far-reaching consequences over and above their potential regional impacts on ecosystems and climate.

Introduction

The Agulhas Current (Figure 4.90) flows along the east coast of South Africa before moving offshore near latitude 34°S and subsequently retroflecting back into the mid-latitude South West Indian Ocean. It creates a coastal dynamic upwelling in the vicinity of Port Alfred and Port Elizabeth bringing nutrient rich water to the surface [1, 2]. High evaporation rates and associated turbulent latent and sensible heat fluxes occur above the Agulhas Current throughout the year due to an important sea surface temperature contrast between the Agulhas

Current and its surroundings. Measurements in the Agulhas Current have shown substantial transfers of water vapour in the marine boundary layer, a deepening of the marine boundary layer due to intense mixing, and unstable atmospheric stability created by the advection of colder and drier air above the current [1, 2]. The intensity of mixing in the local boundary layer is such that cloud lines can often be observed above the current [3]. Rouault et al. [4] have provided evidence of the influence of the Agulhas Current on the evolution of a severe convective storm over southern South Africa. That particular storm, in December 1998, led to severe flooding and a tornado in Umtata that nearly killed President Nelson Mandela when the winds in the town caused a building to collapse. On the global scale, Agulhas water leakage around South Africa controls the exchange of heat and salt between the Indian and Atlantic Oceans and has a role in the Atlantic meridional overturning circulation [5].

*�"��7$3,� ��"��-7)-3�#��-335$�� "��QFF�� )-7��$�;�� $��"��;��+-��+��³;$��?��

��#��F��#��(��Q��B��(;��(F��?��?�F(��**�Q�F��(F��?�� 269

Changes in mean sea surface temperatures

Figure 4.92 (also obtained using 4 × 4 km resolution AVHRR SST) shows the linear trend in sea surface temperature from 1985 to 2007. The most important change is found in the Agulhas Current system, which has warmed by up to 1,5 °C since the 1980s. Rouault et al. [8] have shown that this warming was due to an intensification of the Agulhas Current system in response to an increase in trade wind and a poleward shift in the westerly wind in the South Indian Ocean leading to an overall increase in wind stress curl at relevant latitude. A numerical model that reproduces the observed SST relatively well showed that the transport of the Agulhas Current system had increased since the 1980s leading to the observed warming. This also led to substantial increase in evaporation rate of up to 1 mm per day per decade in the Agulhas Current system and a 50% increase in the leakage of Agulhas water into the South Atlantic. A cooling of up to 0,5 °C per decade occurs at the west coast. Another cooling occurs in the dynamic upwelling cell of Port Alfred and Port Elizabeth where it seems to spread into the Agulhas Current itself and to the west. Cold water seems to have propagated offshore and eastward from the Port Alfred dynamic upwelling cell. Upwelling favorable wind could have contributed to the cooling but an intensification of the Agulhas Current and concurrent intensifying of the dynamic upwelling could be the principal reason of the cooling in that region. The cooling in the west of the country, from Cape Agulhas to the Namibian border, is due to an increased southerly wind. The west coast cooling occurs mostly in autumn and winter [8]. The greatest warming is evident in the Agulhas Current system and the Transkei at all months of the year. The origin of the cooling trends for the west and south coasts is found in an examination of the linear trend in European Center for Medium Range Weather Forecasts and National Centers for Environmental Prediction reanalysed surface wind speed in the region from 1982 to 2007 [8]. It shows that surface wind speed increased in the Southern Atlantic and Indian subtropics. This increased the wind stress curl in the South Indian Ocean and it is at the origin of the intensification of the Agulhas Current system [8].

Mean sea surface temperatures

Figure 4.91, an image obtained using 4 × 4 km resolution Advanced Very High Resolution Radar Sea Surface Temperature imagery (AVHRR SST) [6], shows the 1985-2007 mean sea surface temperature around South Africa. The mean absolute geostrophic ocean current vector derived from merged altimetry [7] is superimposed on the image, which shows the major elements of the Agulhas Current system. The main loop is found south of the continent. The Retroflection is located in the domain delimited by 10°E to 20°E and 37°S to 42°S. Eddies shed from the Agulhas Current can be found as far as latitude 50°S but most of them are usually formed in the Retroflection and move northwestwards towards Brazil. The Agulhas Return Current flows eastwards and meanders from 37°S to 42°S. A coastal upwelling of cold water is evident from Cape Agulhas to Namibia and is the result of strong seasonal southerly wind. This is in contrast to the Port Alfred upwelling cell that is triggered by the Agulhas Current itself. Sporadic wind-driven upwelling also occurs to the east of Cape Agulhas.

*�"��7$3-� ?��-35�)+,,4��QFF��$�?��-336)+,,4��"�� $�


The observed change in sea level pressure and wind speed is consistent with a poleward shift of the westerly wind in the Southern Hemisphere and an increase of the South Atlantic and South Indian Ocean high pressure systems due to intensification of the Hadley circulation and a trend towards a positive phase of the Antarctic Oscillation.

*�"��7$3+� =�� QFF� �� -35�� +,,4$� ?�� -336)+,,4��"�� $�

Conclusion

In conclusion, it seems that the most important changes to the climate and coastal ecosystem in the region is an intensification of the Agulhas Current system since the 1980s. This caused a warming of the Agulhas Current system and a cooling of the Port Alfred upwelling cell. The west and south coast presents a cooling pattern from April to August. All those changes seem to have been triggered by an intensification of the high pressure system in the South Atlantic and South Indian Ocean and a poleward shift of the westerly system.

Acknowledgements

WRC, NRF, PICS, CNRS, IRD, AVISO, NOAA.


Climate change and variability in southern Africa and regional

ocean influences;z\^k�w$;$�FV`kxW w{}^Vj�;$�QV\qVk

Just as the atmosphere exhibits weather and climate variability on a broad range of time scales, so does the ocean. This chapter briefly reviews those natural modes of climate variability that are known to impact on South Africa’s climate and hence on its marine and terrestrial ecosystems. We will see how recent severe flooding and drought events in South Africa are strongly influenced by these climate modes. Such variability can arise in the Pacific Ocean (the El Niño Southern Oscillation), the Southern Ocean (Southern Annular Mode), the Indian Ocean (tropical and subtropical dipole modes) and the Atlantic Ocean (Benguela Niños). Improved long-term monitoring of those ocean regions that impact on South Africa will help to disentangle natural variability and human induced change and allow us to better understand, model and predict the climate.

Introduction

Most of us are used to weather, or the state of the atmosphere at any given instant, changing throughout the day and from one day to the next. Yet people often speak of the climate of a region as if it were constant. Thus, we might say that the winter climate of South Africa tends to be cool and wet in the southwest but sunny and mild in Limpopo. However, the climate of the region is just the average of the weather observed for each hour but calculated over many years (typically 30 years) to try to smooth out daily or weekly changes. If we try to remember whether winter in Cape Town in 2008 was similar to that which we experienced in 2007, we would probably agree that some months were wetter or cooler than the year before. Similarly, if we talk to farmers, we might hear them say that summers in the late 1980s

��#��F��#��(��Q��B��(;��(F��?��?�F(��**�Q�F��(F��?�� 271

*�"��7$36� �� "��$��-��

The El Niño Southern OscillationThe El Niño Southern Oscillation (ENSO) is the largest type of natural variability influencing the oceans. ENSO is a ‘remote influence’ on our weather and climate since it originates in the tropical Pacific. In general, during the summer of a positive ENSO (El Niño) event the tropical Indian Ocean warms, the mid-latitude Indian Ocean cools, the central South Atlantic warms, the mid-latitude South Atlantic cools, the subtropical jet moves north and South Africa is mainly dry. Roughly the reverse patterns occur during a cold ENSO (La Niña) event. Rouault and Richard [1, 2] have shown that the worst drought in Southern Africa happened during an El Niño and conversely the worst wet period during a La Niña. However, the interaction of this natural variability with climate change, such as the Indian

to mid-1990s seemed drier in the northern part of the country than during 2000-2009. Thus, we get a sense that the climate of a region might vary from one year to the next or from one decade to the next. In fact, existing information about the Earth’s state shows us that the climate of the Earth and of any given region varies on all sorts of time scales, from a few years to a few centuries and longer. These variations are collectively referred to as natural climate variability and may result from instabilities in the coupled ocean-atmosphere system (such as the El Niño Southern Oscillation), variations in solar output, volcanic eruptions and other natural processes. If the forcing is particularly strong and global in reach, such as changes in the characteristics of the orbit of the Earth around the Sun, then the resulting impacts may profoundly alter the fundamentals of the Earth’s climate over many thousands of years and then a natural climate change occurs, such as an ice age or an interglacial epoch.Superimposed on such natural climate variability and change are the impacts of humans on the global climate system. These human-induced impacts include increased emissions of greenhouse gases through industrial or transport systems or through intensive agriculture, replacement of natural vegetation by crops or plantations, and the building of large cities. The challenge facing climate scientists is to try to determine what impacts of these human activities might have on our climate, how they can be distinguished from natural climate variability and whether these two factors might interact in such a way as to noticeably exaggerate or weaken their individual impacts. Without properly understanding natural climate variability, it is impossible to be confident about projected changes in the Earth’s climate over the next few decades and centuries in response to increased greenhouse gas emissions.

Modes of climatic variability in southern Africa

South Africa is situated near the meeting place of three oceans: the South Indian Ocean on the east coast, the South Atlantic on the west coast and the Southern Ocean to the south. These three oceans play a vital role in determining southern Africa’s climate and weather patterns and are key drivers of the global climate. Figure 4.93 shows the main types of variability that occur in the oceans surrounding South Africa.


strongly on fisheries in the Benguela upwelling system as well as on rainfall over Angola and Namibia. It is not clear how this important upwelling regime will be impacted under climate change. Due to its importance for the economies and biodiversity of South Africa, Namibia and Angola, it is essential that we are able to monitor variability and change off the west coast of southern Africa, and in particular to better understand and potentially predict natural events such as Benguela Niños and low oxygen events.South of Africa, where the South Indian and South Atlantic Oceans meet, is an extremely variable region, which has been termed the ‘Cape Cauldron’ [11]. Here, large ‘Agulhas Rings’ leave the Indian Ocean, taking heat and salt into the Atlantic. Any changes in this region influence not only South Africa’s weather and climate patterns but also that as far afield as northern Europe. In fact, most of South Africa’s severe flooding events have occurred due to cut-off lows strengthening over the southern Agulhas current [12]. The situation south of South Africa is further complicated by influences coming from as far away as the tropical Indian and Pacific Oceans, which travel across the Indian Ocean and southwards as perturbations in the Agulhas Current eventually causing large disturbances in the cauldron.

The Southern Annular ModeFurther south, in the Southern Ocean, the Southern Annular Mode (SAM), or Antarctic Oscillation, is the main form of natural variability. Studies of the relationships between the SAM, the South Atlantic and Indian Oceans and South African rainfall variability show that when the SAM is in its negative phase, winters over western South Africa tend to be wetter [13]. It has also been found that reduced sea-ice extent in the Antarctic due south of South Africa and increased sea-ice extent further west near the Antarctic Peninsula is associated with more winter rainfall [14]. Analysis of observations and computer model experiments have indicated that wetter or drier winters are also influenced by certain SST patterns in the subtropical to mid-latitude South Atlantic [15]. These patterns, combined with the influence of ENSO and other modes of variability in the southern oceans, point to a complex interplay of factors that can influence the weather and climate over South Africa.

Ocean warming since the 1970s, has led to drought becoming more intense and widespread during El Niño events [3, 4]. This highlights the complex interactions between natural variability and climate change.La Niña events tend to follow El Niños and the whole cycle of ENSO occurs approximately every four to seven years. However, our ability to predict the impact of these events is not perfect as these events often coincide with other natural variability in the ocean, confusing the signal. An example in the tropical Indian Ocean is the Indian Ocean dipole (IOD) (or zonal mode). This is a coupled ocean-atmosphere phenomenon occurring every few years that generates in this ocean typically during June or July and dissipates by November or December. During ‘positive’ events, the dipole consists of cooler sea surface temperatures (SSTs) in the southeast tropical Indian Ocean and warmer waters in the west. These changes in the sea temperature lead to a shift in the normal convection, with heavy rainfall over equatorial east Africa and droughts over the Indonesian region. The negative phase of the IOD brings about the opposite conditions, with warmer water and greater precipitation in the eastern Indian Ocean and cooler and drier conditions in the west [5]. At higher latitudes, sea surface temperature dipole events can also occur every few years in the subtropics to mid-latitudes of both the South Indian and South Atlantic oceans during summer. Positive events consist of warmer SSTs in the NE South Indian Ocean and cooler SSTs in the SW, and similarly in the South Atlantic, resulting in reduced rainfall over southern Africa during the Southern Hemisphere summer [6, 7, 8]. These dipole events often coincide with ENSO events and the relationship between them is not clear. It is further evident that the characteristics of these modes of variability are changing with time, thus the addition of anthropogenic climate change makes the situation much more difficult to disentangle and predict.

The ‘Benguela Niño’Another influential form of variability in the South Atlantic is the ‘Benguela Niño’ [9, 10], in which the usual cold upwelled water along the coasts of southern Angola and northern Namibia is replaced by anomalously warm water every few years during late summer and autumn. These events impact

��#��F��#��(��Q��B��(;��(F��?��?�F(��**�Q�F��(F��?�� 273

*�"��7$37� *��$��-4��

Conclusion

Variability in either of the two major oceanographic regions along our coastline – the Agulhas Current and the Benguela Current − as well as the Southern Ocean, can impact on our every day lives, yet little is understood about their natural variability. Thus, disentangling the impacts of climate change in these regions is essential. We need to gain a better understanding of how this natural variability modulates the regional rainfall as it has major implications for forecasting, and hence for water and agriculture. Improved in situ monitoring, remote sensing and ocean modelling will help us to begin to understand these natural variations and how they are changing over time. As our understanding of the importance of the oceans grows, it is becoming more and more vital that better monitoring programmes are put in place.


The impacts of ocean acidification on a keystone

Southern Ocean species�^q��$�/V\W`\X

It has been predicted that by the year 2050 certain regions of the Southern Ocean will experience severe ocean acidification. Such a change in ocean chemistry will have extremely negative implications on the pelagic ecosystem. The shell-forming pelagic snails (pteropods), which are such integral members of the Southern Ocean ecosystem, will most likely disappear from the region. Furthermore, the important role that these organisms play in transferring carbon from the surface waters through the food chain and to the ocean depths will be detrimentally affected.

What is ocean acidification?

For around 400 000 years prior to the industrial revolution, carbon dioxide (CO2) levels in the Earth’s atmosphere remained relatively constant at around 200 parts per million (ppm). The industrial revolution saw vast quantities of CO2 being emitted into the atmosphere, increasing concentrations to present levels of 380 ppm [1]. CO2 is a major greenhouse gas and contributes significantly to global warming. The ocean plays a fundamental role in regulating atmospheric CO2 and helps to moderate the effects of climate change by taking up atmospheric CO2. Around 30% of total atmospheric CO2 has been absorbed by the world’s oceans over the last few decades [2]. This has important implications for reducing global warming, but with this comes the extremely negative effect of increased ocean acidity. As CO2 is dissolved in the surface of the ocean various chemical processes take place resulting in the pH (the acidity/alkalinity) of the seawater becoming lower, or more acidic [3]. An increase in acidity will cause the exoskeletons or shells (made up of calcium carbonate) of certain marine organisms to dissolve. If


*�"��7$3�� %�Lima helicina. �� "�� (�� 9�� ?��F��

the business-as-usual approach to CO2 emissions (IS92a emissions scenario) is followed, changes in ocean pH levels may occur that far exceed any experienced in the past 300 million years [4]. It is important to point out, though, that although ocean pH is decreasing, the oceans are not actually becoming acidic, rather they are becoming less alkaline.

How will changes in ocean pH affect marine calcifying organisms?

The surface waters of the Southern Ocean are likely to be affected by ocean acidification within the next 50 years [3]. This means that any Southern Ocean marine organism that takes up calcium carbonate to create its shell or exoskeleton could potentially be removed from the ecosystem. In the Southern Ocean, the shelled pelagic snails (called pteropods or sea butterflies) are likely to be negatively affected by ocean acidification [1, 3, 5] (Figure 4.95). Recent studies show that within 48 hours, the shells of living pteropods dissolve in seawater with reduced pH [1, 3]. The prognosis does not look good for pteropods. These animals are unlikely to survive the rapid changes in ocean pH that will occur in the Southern Ocean by 2050 [3]. The most probable scenario is that pteropods will disappear from the Southern Ocean, either shifting northwards into less acidic waters, or dying off altogether. The implications are likely to be far-reaching and would affect the structure, biodiversity and food webs of Southern Ocean pelagic ecosystems [3, 6, 7].

How will these changes impact Southern Ocean pelagic ecosystems?

Why does it matter how pelagic ecosystems are structured?Carbon in the surface waters of the ocean is taken up by phytoplankton through the process of photosynthesis. The carbon is then transferred up the food chain. If most of the phytoplankton is consumed by small zooplankton the carbon tends to be recycled in the surface waters and will eventually be returned to the atmosphere. This is known as the short-lived carbon pool, since carbon in this pool only remains there for a short time, anywhere from hours to a few days [8]. On the other hand, if most of the phytoplankton is

��#��F��#��(��Q��B��(;��(F��?��?�F(��**�Q�F��(F��?�� 275

of mucous strings during feeding [18, 20, 21], and through the sinking of their shells when they die [22].Pteropods clearly contribute to the regulation of atmospheric carbon by the oceans and play a major role in the structure and functioning of pelagic ecosystems. They can therefore be considered a keystone species.

What needs to be done?

The degree of ocean acidification that has been predicted to occur over much of the Southern Ocean by 2050 will have severe knock-on effects. Pteropods will most likely disappear from those regions. This will impact on the shell-less pteropods and other carnivorous zooplankton that feed on them, as well as on the higher predators, such as fish, that are also known to feed on pteropods. Apart from influencing the food chain of the Southern Ocean pelagic ecosystem, the loss of these pteropods will also have negative affects on the transfer of carbon to the sequestered carbon pool. Although this is generally only significant on a regional scale, it would have implications for the role that the Southern Ocean plays in acting as a carbon sink. Unfortunately, there is no way of preventing ocean acidification if the business-as-usual approach (IS92a) to carbon emissions continues.Very little is known about the impacts that ocean acidification will have on the Southern Ocean. Although pteropods will be severely affected, the impact of ocean acidification on other organisms, such as krill, is largely unknown. It is therefore essential that funding be made available to researchers to conduct studies to improve our understanding of the issue. Ocean acidification will not only affect the Southern Ocean (although this will be the region affected first). Eventually the oceans nearer the tropics will be influenced by ocean acidification, which will have extremely negative consequences for coral reefs. Research into how these fragile but extremely productive ecosystems might be impacted is urgently needed.

consumed by larger zooplankton and, in turn, top predators (including fish, seals and whales), the carbon will enter the long-lived carbon pool, so named because many of the top predators will live a long time, from one to tens of years [8]. Phytoplankton that is consumed by larger zooplankton may also result in carbon being transferred into the sequestered carbon pool [8]. This pool of carbon is stored in the deep ocean where it can remain for hundreds to thousands of years. This is the most important carbon pool in terms of the ocean’s ability to reduce atmospheric CO2 levels by acting as a carbon sink. The structure of pelagic ecosystems (which phytoplankton and zooplankton dominate) therefore plays an extremely important role in the global carbon cycle.

Where do pteropods fit in?By definition, a keystone species is one that is not necessarily abundant in a community, but that exerts a strong control on the community structure by nature of its ecological role. In Southern Ocean pelagic ecosystems, pteropods can be considered as a keystone species. Recent studies have shown how important pteropods are in the Southern Ocean, particularly the role that they play in carbon transfer [6, 7]. Pteropods are important components of the pelagic food web, being both major consumers of phytoplankton and key prey items for higher trophic levels [6, 7]. Consuming vast quantities of phytoplankton, shelled pteropods are able to transfer carbon either to the deep sea (sequestered carbon pool) or to higher trophic levels (long-lived carbon pool). Also, the shelled pteropods are the exclusive food source for a group of shell-less pteropods inhabiting the Southern Ocean [7, 9]. The disappearance of the shelled pteropods due to ocean acidification will almost certainly result in the loss of their shell-less counterparts [7]. Shelled pteropods are also known to be important prey items for certain fish species [10, 11] and carnivorous zooplankton [12-16]. In this way, pteropods contribute to the transfer of carbon away from the short-lived carbon pools and into the long-lived and sequestered carbon pools. In addition to their role in the pelagic food web, pteropods contribute to the transfer of carbon to the sequestered carbon pool through various other mechanisms [7], including the production of large, fast sinking faecal pellets [17-19], the development

Afterword

276

SAEON’s approach toward long-term environmental

observation�^q�8$��;xWWx\�

The South African Environmental Observation Network (SAEON) mandate is to deliver knowledge about the impact of global change on South Africa’s life-support systems. Earth observation using remote sensing coupled with in situ observation offers an approach of recording change, distinguishing natural variability from anthropogenic change and identifying the relative contribution of different drivers acting simultaneously and synergistically. The scope of observation is 19 natural and anthropogenic drivers acting on biodiversity, bio-geochemical cycling, productivity, hydrological functioning, sediments, disturbance regimes and marine geophysical patterns. Four complementary approaches are pursued: monitoring of geographically dispersed sites; process-level observation of intensively observed sites; study of selected, well-defined ecosystems; and investigation of cross-cutting or novel themes. Our environment is changing at an unprecedented rate in response to anthropogenic impacts that threaten to disrupt ecological processes and the sustainable use of our natural resources. The potential impact of such change on the world’s economic and social fabric has demanded a political response [1]. However, policy prescription and decision making requires quality information about environmental change, and successful mitigation and adaptation responses cannot be formulated unless there is clear understanding of what is driving certain impacts. Long-term environmental observation has emerged globally as a key approach for meeting these

AFTERWORD 277

knowledge needs. SAEON was constituted with the mandate ‘to develop and sustain a dynamic South African observation and research network that provides the understanding, based on long-term information, needed to address environmental issues’ [2]. This volume illustrates some environmental changes taking place in South Africa and the manner in which they are being monitored (Pauw et al., p5). Environmental change is about human well-being and economic security, which is highlighted by the increasing importance attached to ecosystem services [3] – a theme that resonates throughout this volume. Rangelands deliver agricultural goods and provide hydrological services, carbon sequestration, and energy (Milton and Dean, Section 3, p74); the well-being of rural communities is tied directly to their natural resource base (Twine, Section 1, p17; Erasmus et al., Section 1, p20); coastal fisheries is an industry of national importance (Brundrit, Section 4, p211) that is threatened by change (Bernard et al., Section 4, p233; Van der Lingen et al., Section 4, p252; Cockroft, Section 4, p257); and our water supply faces diverse threats (Le Maitre et al., Section 4, p193). There will be mounting costs for mitigating undesirable environmental changes (Van Wilgen, Section 3, p125) and for maintaining infrastructure and services in the face of sea level rise (Theron, Section 4, p212; Mather, Section 4, p217; Brundrit et al., Section 4, p227). Droughts, floods and storms will also have an increasingly adverse economic impact (Vogel, Section 1, p36; Smith et al., Section 4, p222). Can our ecosystems continue to deliver adequate services in the face of unheralded environmental change? Realistic projection of the rate and extent of environmental change is fundamental for successful adaptation and mitigation of its impacts. However, ecosystems, even those simplified by humans, are complex. Trying to understand how ecosystems work and to predict how they might change was difficult enough, even before they were faced with an array of novel human-induced impacts. Yet, as scientists, we face an ever increasing demand to achieve just this, which requires well designed surveillance of change. This chapter outlines SAEON’s approach to environmental observation in the context of current efforts revealed in this volume.

SAEON’s aims: building on current efforts

SAEON is a network organisation that works toward understanding environmental change through collaboration with government and other agencies, academic institutions and civil society. This volume provides an overview of its starting platform and portrays the breadth and depth of the current observation effort. SAEON intends to expand this platform in the context of its core science framework [4]. The following review identifies current strengths and gaps to be filled in order for SAEON to meet this aim. Effective observation of environmental change requires explicit identification of the drivers of change and responses of interest (Table 1). It is readily apparent that many of SAEON’s interests are well met by current efforts. This volume emphasises that a deeper understanding of both physical and socio-politico-economic ‘drivers of the drivers’ is mandatory. Oceans are foremost among the physical drivers because of their control of climate (Lutjeharms, Section 4, p263), whereas human population trends are the critical socio-economic driver (Kok and Van Tonder, Section 1, p12). The dichotomous nature of this country – a burgeoning rural population depending directly on natural resources versus an urban market-oriented society (Twine, Section 1, p17; Erasmus et al., Section 1, p20) – underscores the fact that human impacts are a product of both human numbers and global patterns of consumption. Even minor human activities, such as keeping exotic pets, may have substantial impacts (Van Wilgen and Richardson, Section 3, p135).


��#��;��

��

��F��

��

;��

��

;��"� �+,��+��4��55��3+��

�-63��-56��-54��+-+��

�+++��+65��+7+��+74��

�+�+��+�4��+�7��+�5

/�� 43��5��3+��-+��

�-+4��-6,��-6��

�-63��-74��-�-��

�-56��-54��-3,��

�+74

CO+��" �5��+46 /��"��"

�+66

?��"��&�� +--��+66��+�5��+4, 9�� 43��55��3+��34��

�-,7��-,3��--��

�++4

�� 9-56��+--��+-+��+-4��

�+++��++4��

�47��-,3��-56��

�+66��+�+��+�4��

�+46

B��)�� +++

=��"�� -4��4-��43��5��

�-,7��-��-��-�-��

�-�5��-47��-36

Q��"�� "

9-�5��-47��-36��

�-34��

;��:��"��

�+65 #��"��

Q�� " �+7+��+74��+�+��+�4 ?��"��&��

�+�7��+�5

�� 74

��" �-56

9�� ! �74��+7+��+74

#�� +74

9��

��"�� -+��-+4��-6,��-6��

�-63��-74��-3,

#��"��

Q��"�� " �-56��-3,

�� -56��+-+

=��"�� 6��+++

8��"�� 4

��-� =��;��%�+,,3�$

This volume highlights current priorities for drivers and responses (Table 1). For drivers, these are climate variability and change (seventeen chapters), land use and management (eleven chapters), alien organisms (seven chapters) and sea level rise (six chapters). Other important drivers are marine geophysical patterns, harvesting, pollution and poisons, hydrological functioning, CO2 loading, sediments, and Large Infrequent Events (LIE). Less attention is paid to coastal/marine use or management, acid deposition, nutrient loading, disease, or the effects of two or more drivers; and no papers deal with ultra-violet radiation, pests, disturbance regimes, or geomorphological processes. Coverage of land use centres on mining, rural systems, and livestock ranching, with limited attention to other forms of production agriculture. Responses receiving close attention (Table 1) are biodiversity (fourteen chapters), primary production (eight chapters), secondary production (seven chapters), and hydrological functioning (four chapters), with observation also of marine geophysical patterns, biogeochemical cycling, and sediments. Disturbance regimes are not considered.Overall, the content of this volume shows a healthy foundation upon which to launch a national environmental observation initiative.

What ‘tools’ are at our disposal?

Available methods determine the rate of progress of a scientific discipline. This volume illustrates well that environmental observation can be successfully achieved using three main complementary tools, namely, remote sensing, in situ observation and projection modelling, which together offer the required scale, detail and understanding.Remote sensing offers a large spatial scale of observation and increasingly fine spatial resolution as technology advances. What is its relationship with in situ observation? In some cases remote sensing can be used as the primary tool for inventory or monitoring change of specific features, for example, detection of alien plants (Van Aardt et al., Section 3, p147), mapping wetland change (Pillay, Section 4, p201), assessing and monitoring degradation (Van Aardt et al., Section 3, p97; Wessels et al., Section 3, p104), following subcontinental phenological change (Wessels et al., Section 3, p88) and assessing the impact of an ENSO event (Wessels and Dwyer, Section 3,

AFTERWORD 279

p92). In other cases, ground-based data are needed to complement remote sensing (Erasmus et al., Section 1, p20; Wessels and Dwyer, Section 3, p92; Wessels, Section 3, p104; Van Aardt et al., Section 3, p147; Lutjeharms, Section 4, p264;). In a few cases, close integration between the two has been achieved when process-level observation is required, such as with intensive production systems like plantation forests and citrus orchards (Van Aardt et al., Section 3, p116).Modelling is the third required component that allows integration of different drivers and response variables, as shown for a communal rangeland (Richardson and Hoffman, Section 3, p109) and the response of the Agulhas current to climate variability (Reason and Hermes, Section 4, p270). Modelling of physical systems, such as ocean behaviour, is achievable (Lutjeharms, Section 4, p264), but successful projection of the response of complex biological systems is a challenge which awaits us. In all cases, in situ observation is needed for the development, validation and verification of models. SAEON will therefore foster in situ observation in order to address process-level questions, assist remote-sensing efforts of sister agencies and contribute to modelling activities in the manner that [5] GTOS and GOOS [6] function. This volume offers additional lessons on observation approaches. First, ‘old technology’ is not redundant, as shown by the use of repeat lateral photography for examining vegetation change (Hoffman and Rohde, Section 3, p79) and aerial photography for studying bush encroachment (Ward, Section 3, p85). These studies further illustrate that understanding future change demands an understanding of past change; a refrain echoed in the accounts of acid drainage from coal mines (McCarthy and Pretorius, Section 3, p168) and historical changes in fish distributions (Skelton and Coetzer, Section 4, p190). Second, in situ observation can be streamlined through using appropriate indicators of a specific impact. For example, phenology can reveal climate change at a subcontinental level (Wessels et al., Section 3, p88) and pteropods could serve as an indicator of ocean acidification (Bernard, Section 4, p273). What attributes should a successful indicator possess? Crawford and Ryan (Section 4, p247) contend that top-of-the-web predatory seabirds reflect an integrated response of coastal and

marine systems; similarly pteropods are critical components of their food web (Bernard, Section 4, p273). It is not practicable to monitor all physico-chemical variables, so The River Health Programme uses bio-indicators for monitoring water quality (Sekwele, Section 4, p197). Third, observation design is improved if projections are made of expected responses based on best understanding, such as consideration of plant attributes for assisting in predicting alien invasiveness (Iponga, Section 3, p127), changes in marine currents and upwelling patterns (Reason and Hermes, Section 4, p270) that can have consequent effects on fisheries (Bernard et al., Section 4, p233; Rouault et al., Section 4, p268), and adjustments of coastal systems to sea level rise (Theron, Section 4, p212; Mather, Section 4, p217; Griffiths and Mead, Section 4, p242).

Scale and complexity of the observation challenge

Natural variability of dynamics with a long-term cycle may be easily confused with directional change. Observation needs to distinguish between the two so that clear inference can be made about human-induced change (Pauw, p5). This volume presents a number of cautionary examples in which it is equivocal whether directional change or natural variability is evident. Recently observed changes in our ocean’s currents may be part of natural variability (Reason and Hermes, Section 4, p270); the eastward shift of sea fisheries (Van der Lingen et al., Section 4, p252) and rock lobster (Cockroft, Section 4, p257) has occurred before and it is not clear whether this event is of greater magnitude or is the beginning of a directional change; and the KZN storm in 2007 (Smith et al., Section 4, p222) may simply have been an LIE coincident with an infrequently occurring constellation of factors, or perhaps its impact was exacerbated by sea level rise or altered wind patterns (Theron, Section 4, p212; Brundrit et al., Section 4, p227).The complexity of anthropogenic impact on naturally variable ecosystems is well illustrated by estuaries (Whitfield and Matlala, Section 4, p181; James and Paterson, Section 4, p183), sea level rise, increase or decrease in freshwater inputs (impoundments, abstraction, inter-basin transfers, climate change), consequent changes in sediment input plus the effect of catchment-level changes in land use and management, nutrient loading and pollution (each


kind has a specific effect), changes in nutrient availability because of altered upwelling patterns, changes in sea surface temperature, ocean acidification, carbon loading, harvesting, ongoing invasion of alien organisms, and extreme storm events (Smith et al., Section 4, p222). These are first-order impacts, but as Ward (Section 3, p85) cautions, be wary of single-agent explanations of change. Responses will be complex because most drivers are multi-faceted (for example, impact of nutrient loading differs for nitrogen versus phosphorus), interact with others (Erasmus et al., Section 1, p20; Chown et al., Section 3, p139) and have indirect effects, and response variables can show a complex integrated response (for example, trophic cascades). Responses may also be contrary to expectations. This is evident in sea temperatures along the eastern coastline increasing at some locations (James et al., Section 4, p187) but decreasing at others owing to altered upwelling patterns (Griffiths and Mead, Section 4, p242). This complexity of anthropogenic change plays out against a backdrop of the natural variability of climate, disturbance, and LIEs across marine, terrestrial and aquatic ecosystems. Can observation hope to distinguish the effect of so many different drivers so that causes of change are understood? SAEON has stratified observation according to the country’s main biomes (marine, coastal, fynbos, grassland, forest, wetland, savanna, arid). For each, the observation design is intended to realise the following objectives:(a) Distinguish directional change from natural variability.(b) Identify the responsible drivers. (c) Define the relative effect of each driver and determine if there are complex

effects. (d) Assess ecosystem responses to a complex set of drivers. (e) Project future changes based on process-level knowledge. These are formidable goals for which a four-pronged observation approach has been devised.

SAEON observation approach

This section describes SAEON’s four-pronged observation approach:

(a) In situ observation across geographically distributed sites in order to identify the relative influence of different drivers.

(b) Intensively observed sites for gaining a process-level understanding of certain drivers and responses.

(c) Observation of selected, discrete ecosystems in order to ensure realism that may not be evident in site-based observation.

(d) Comparison across biomes for cross-cutting themes.

Identifying the effect of individual driversExperimental approaches can show that a certain driver agent may have an effect, but observation is needed to demonstrate the scale of its effect in an ecosystem. If multiple drivers impact a system at any one time, how can the influence of one driver be isolated? SAEON’s design for this component is based on using the spatio-temporal ‘signature’ of each driver to distinguish its effect from those of others [4]. Impact of a driver ranges from pervasive and consistent through to local and infrequent (cf. ‘press-pulse’ distinction of Bender et al. [7]). At one extreme, the effect of different land uses and land management approaches are easily compared across fence lines. In effect, most landscapes in this country offer a well replicated experiment (see Götz, Section 4, p238, for a marine example using marine protected areas). In terms of temporal patterns, impact of an LIE is easily recorded with appropriate temporal resolution of sampling; the impact of a land transformation is revealed by monitoring before and after. At the other extreme there are variables that offer no spatial controls for comparison or display step-like changes through time. Atmospheric CO2 has been increasing monotonically and uniformly across the globe since the 1950s. Some effects of carbon loading have been identified because process-level understanding has been gained. One example is the impact of ocean acidification through increased absorption of atmospheric CO2 on marine systems (Bernard, Section 4, p273). A second purported example is bush encroachment resulting from the differential advantage of C3 versus C4 photosynthetic pathways in relation to atmospheric CO2 concentration (Ward, Section 3, p85). Prior to this, bush encroachment was explained only in terms of land management impacts. Maximum use is to be made of responses which have a ‘one-on-one’

AFTERWORD 281

correspondence with a driver, such as biota, whose distribution is strongly controlled by temperature (James et al., Section 4, p187).

Process-level observation of intensive sitesImpacts which require detailed process-level understanding are addressed through intensive observation of sites of about 100 ha, based on the GTOS�/�GOOS approach. The main example is to increase understanding of the impact of increasing atmospheric carbon and climate change on carbon cycling through process-level modelling of carbon flux, biogeochemical cycling, water balance and primary productivity. The intensity of this effort would limit it to one site per biome, requiring selection of a representative vegetation type and land use.

Observation of selected ecosystemsSite-based observation is biased toward drivers and responses that can be observed at a reduced spatial scale. Scale-related dynamics that occur in larger ecosystems will not likely be apparent. For example, rivers are best understood at a catchment level; secondary production can only be assessed at the scale of a production unit. Observation of distinct ecosystems, defined as a geographic area that functions as a relatively discrete entity, is therefore a third approach in order to achieve broader realism. This approach equates with the Long-Term Ecological Research sites in the US and elsewhere. Comparable examples in this volume are the Namaqualand communal grazing lands (Richardson and Hoffman, Section 3, p109) and Marion Island (Chown et al., Section 3, p139). An advantage of both is that they are relatively simple systems; the first-mentioned being driven by climate and livestock, the second by climate and alien organisms. Another suitable attribute is a system in which an intervention has taken place, as, for example, shown for dune mining followed by rehabilitation (Van Aarde et al., Section 3, p161). The challenge is to expand this approach to more complex systems, to which end SAEON has commenced observation of Algoa Bay, the Drakensberg, and Table Mountain National Park. These well-studied systems have a baseline that should assist in interpretation of major changes, such as port construction in Algoa Bay.

Cross-cutting themesThe comparative approach is a powerful observation tool. SAEON will pursue cross-cutting themes across biomes such as rangeland degradation and harvesting. Rangeland degradation has similar causes and consequences, but also important differences, across land uses and across biomes (Hoffman, Section 3, p71; Milton and Dean, Section 3, p74; Van Aardt et al., Section 3, p97; Wessels, Section 3, p104; Richardson and Hoffman, Section 3, p109). Likewise, harvesting of individual species is a major impact in marine, coastal, and terrestrial environments, whose ramifications permeate the trophic web (Crawford and Ryan, Section 4, p247; Van der Lingen et al., Section 4, p252).

Conclusion

Environmental change is not new. Many anthropogenic impacts, such as land transformation, poor land management, mining, pollution, harvesting, poisons, nutrient loading, altered disturbance regimes, alien organisms and pests, have been evident for a long time. These impacts are set to continue and may intensify. So are novel human-induced impacts, such as climate change and sea level rise. Our natural, semi-natural and production systems are faced with unprecedented human-induced change. SAEON will pursue in situ observation, complemented by the remote-sensing efforts of sister agencies, to help provide the understanding essential for adapting to and mitigating anthropogenic change. The driver variables reflect the most important anthropogenic and natural agents forcing change of the main ecosystems of the country. The response variables represent the key pre-determined areas of interest for SAEON. A response variable may be affected by multiple driver variables but the identity of these would depend on the ecosystem in question.


ReferencesINTRODUCTION[1] Department of Environmental Affairs and

Tourism (2006). South Africa environment outlook: a report on the state of the environment. Pretoria: Department of Environmental Affairs and Tourism.

SECTION 1 – PEOPLE AND ENVIRONMENTAL CHANGEHuman population trends in South Africa

[1] Population Reference Bureau (PRB) (2008). World population highlights: Key findings from PRB’s 2008 World Population Data Sheet. Population Bulletin [online] 63, 3 September 2008. Available from: http://www.prb.org/.

[2] World Bank (2008). World Development Indicators 2008 Database. Regional Fact Sheet for sub-Saharan Africa [online]. Washington DC. Available from: http:// www.worldbank.org/.

[3] Statistics South Africa (2008). Mid-year population estimates 2008. Statistical Release P0302 [online]. Pretoria. Available from: http://www.statssa.gov.za/publications/P0302/P03022008.pdf.

[4] Kok P & Collinson M (2006). Migration and urbanisation in South Africa. Report 03-04-02 [online]. Pretoria: Statistics South Africa. Available from: http://www.statssa.gov.za/publications/Report-03-04-02/Report-03-04-02.pdf.

[5] United Nations (2009). World urbanization prospects: The 2007 revision population database [online]. New York: Population Division, Department of Economic and Social Affairs. Available from: http://esa.un.org/unup/p2k0data.asp.

[6] United Nations (2009). World population prospects: The 2008 revision. Annex Tables [online]. New York: Population Division, Department of Economic and Social Affairs. Available from: http://esa.un.org/unpp/ index.asp.

[7] United Nations (2009). World population prospects: The 2008 revision. Panel 2 Detailed Data [online]. New York: Population Division, Department of Economic and Social Affairs. Available from: http://esa.un.org/unpp/ index.asp.

[8] Warner K, Afifi T, Dun O & Stal M (2009). Climate Change and Migration: Reflections on Policy Needs. MEA Bulletin [online] Guest Article No. 64, February 2009. Available from: http://www.iisd.ca/mea-l/guestarticle64.html.

[9] Black R, Kniveton D, Skeldon R, Coppard D, Murata A & Schmidt-Verkerk K (2008). Demographics and climate change: Future trends and their policy implications for migration. Working Paper No. T-27 [online]. Brighton: University of Sussex (Development Research Centre on Migration, Globalisation and Poverty). Available from: http://www.migration drc.org/publications/working_papers/WP-T27.pdf.

[10] Couldrey M & Herson M (eds) (2008). Climate change and displacement. Forced Migration Review [online] Issue 31, October 2008. Available from: http://www.fmreview.org/FMRpdfs/FMR31/FMR31.pdf.

[11] Hugo G (2008). Migration, development and environment. Geneva: International Organization for Migration (IOM) [online]. Available from: http://www.iom.int/jahia/webdav/site/myjahiasite/shared/shared/mainsite/published_docs/serial_publica tions/MRS35_updated.pdf.

REFERENCES 283

[2] Parsons DAB, Shackleton CM & Scholes RJ (1997). Changes in herbaceous layer condition under contrasting land-use systems in the semi-arid lowveld, South Africa. Journal of Arid Environment 37:319-329.

[3] Higgins SI, Shackleton CM & Robinson ER (1999). Changes in woody community structure and composition under contrasting landuse systems in a semi-arid savanna, South Africa. Journal of Biogeography 26:619-627.

[4] Shackleton CM (1993). Demography and dynamics of the dominant woody species in a communal and protected area of the eastern Transvaal Lowveld. South African Journal of Botany 59:569-574.

[5] Desmet PG, Shackleton CM & Robinson ER (1996). The population dynamics and life-history attributes of a Pterocarpus angolensis DC. population in the Northern Province, South Africa. South African Journal of Botany 62: 160-166.

[6] Shackleton CM, Griffin NJ, Banks DI, Mavrandonis JM & Shackleton SE (1994). Community structure and species composition along a disturbance gradient in a communally managed South African savanna. Vegetatio 115: 157-167.

[7] Harrison YA & Shackleton CM (1999). Resilience of South African communal grazing lands after the removal of high grazing pressure. Land Degradation and Development 10: 225-239.

[8] Shackleton CM (2000). Comparison of plant diversity in protected and communal lands in the Bushbuckridge lowveld savanna, South Africa. Biological Conservation 94:273-285.

[9] Smart R, Whiting M & Twine W (2005). Lizards and landscapes: Integrating field surveys and interviews to assess the impact of human disturbance on lizard assemblages and selected reptiles in a savanna in South Africa. Conservation Biology 122:23-31.

[10] Shackleton CM, Shackleton SE & Cousins B (2001). The role of land-based strategies in rural livelihoods: The contribution of arable production, animal husbandry and natural resource harvesting in communal areas in South Africa. Development Southern Africa 18: 581-604.

[11] High C & Shackleton CM (2000). The comparative value of wild and domestic plants in home gardens of a South African rural village. Agroforestry Systems 48:141-156.

[12] Dovie DBK, Witkowski ETF & Shackleton CM (2003). Direct-use value of smallholder crop production in a semi-arid rural South African village. Agricultural Systems 76:337-357.

[13] Twine W, Moshe D, Netshiluvhi T & Siphugu V (2003). Consumption and direct-use values of savanna bio-resources used by rural households in Mametja, a semi-arid area of Limpopo province, South Africa. South African Journal of Science 99:467-473.

[14] Dovie D, Shackleton C & Witkowski E (2006). Valuation of communal area livestock benefits, rural livelihoods and related policy issues. Land Use Policy 23:260-271.

[15] Banks DJ, Griffin NJ, Shackleton CM, Shackleton SE & Mavrandonis JM (1996). Wood supply and demand around two rural settlements in a semi-arid savanna, South Africa. Biomass and Bioenergy 11:319-331.

[16] Dovie DBK, Shackleton C & Witkowski ETF (2002). Direct-use values of woodland resources consumed and traded in a South African village. International Journal of Sustainable Development and World Ecology 9:269-283.

[17] Hansen B (1998). Changing patterns of natural woodland resource dependency and use: Intergenerational perceptions, traditions and customs. MSc thesis. Copenhagen: University of Copenhagen.

[18] Shackleton CM & Shackleton SE (2004). The importance of non-timber forest products in rural livelihood security and as safety-nets: evidence from South Africa. South African Journal of Science 100:658-664.

[19] Seekings J (2000). Visions of society: Peasants, workers and the unemployed in a changing South Africa. Journal for Studies in Economics and Econometrics 24:53-71.

[20] Simpkins C (1981). Agricultural production in the African reserves of South Africa, 1918-1969. Journal of Southern African Studies 7:256-283.

[21] Wolpe H (1972). Capitalism and cheap labour-power in South Africa: From segregation to apartheid. Economy and Society 11:425-456.

[22] Aliber M (2003). Chronic poverty in South Africa: Incidence, causes and policies. World Development 31:473-490.

[23] Shackleton SE (2005). The significance of the local trade in natural resource products for livelihoods and poverty alleviation in South Africa. PhD thesis. Grahamstown: Rhodes University.

[24] Ostrom E (1990). Governing the commons: The evolution of institutions for collective action. Cambridge: Cambridge University Press.

[25] Kirkland T, Hunter LM & Twine W (2007). “The bush is no more”: Insights on institutional change and natural resource availability in rural South Africa. Society and Natural Resources 2: 337-350.

[26] Twine WC (2005). Socio-economic transitions influence vegetation change in the communal rangelands of the South African Lowveld. African Journal of Range and Forage Science 22: 93-99.

[27] Twine W, Siphugu V & Moshe D (2003). Harvesting of communal resources by ‘outsiders’ in rural South Africa: a case of xenophobia or real threat to sustainability? International Journal of Sustainable Development and World Ecology 10:1-12.

[28] Madubansi M & Shackleton CM (2006). Changing energy profiles and consumption patterns following electrification in five rural villages, South Africa. Energy Policy 34: 4081-4092.

[29] Madubansi M & Shackleton CM (2007). Changes in fuelwood use and selection following electrification in the Bushbuckridge lowveld, South Africa. Journal of Environmental Management 83:416-426.

[30] Kahn K, Tollman SM, Collinson MA, Clark SJ, Twine R, Clark BD, Shabangu M, Gomez-Olive FX, Mokoena O & Garenne ML (2007). Research into health, population and social transitions in rural South Africa: Data and methods of the Agincourt Health and Demographic Surveillance System. Scandinavian Journal of Public Health 35:8-20.

[12] Adamo S (2008). Addressing environmentally induced population displacements: a delicate task. Background Paper for the Population-Environment Research Network Cyberseminar on ‘Environmentally Induced Population Displacements’ [online], 18-19 August. Available from: http://www.population environmentresearch.org/papers/ sadamo_pern2008.pdf.

[13] Myers N (2002). Environmental refugees: a growing phenomenon of the 21st century. Philosophical Transactions of the Royal Society B [online] 357:609-613. Available from: http://www.jstor.org/pss/3066769.

[14] Almeria Statement (1994). First International Symposium on Desertification and Migration [online] (Almería, February 1994). Available from: http://www.sidym2006.com/eng/eng_doc_interes.asp.

[15] UNHCR (2002). Environmental migrants and refugees. Refugees [online] No. 127. Available from: http://www.unhcr.org/pub/ PUBL/3d3fecb24.pdf.

[16] UNFCCC (2007). Climate change: impacts, vulnerabilities and adaptation in developing countries [online]. Bonn: UNFCC Secretariat. Available from: http://unfccc.int/files/essential_background/background_publications_htmlpdf/application/txt/ pub_07_impacts.pdf.

[17] Bierman F & I Boas (2007). Preparing for a warmer world. Towards a global governance system to protect climate refugees. Amsterdam: Global Governance Project [online]. Available from: http://www.glogo/org/images/doc/ WP33.pdf.

[18] Stern N (2006). Stern Review on the Economics of Climate Change [online]. London: HM Treasury. Available from: http://webar chive.nationalarchives.gov.uk/+/http://www.hm-treasury.gov.uk/independent_reviews/stern_review_econom ics_climate_change/stern_review_report.cfm.

Drivers of natural resource use by rural households in the Central Lowveld

[1] Giannecchini M, Twine W & Vogel C (2007). Land-cover change and human-environment interactions in a rural cultural landscape in South Africa. The Geographical Journal 173: 26-42.


[31] Dovie DBK, Witkowski ETF & Shackleton CM (2004). The fuelwood crisis in southern Africa – relating fuelwood use to livelihoods in a rural village. GeoJournal 60:123-133.

[32] Dovie DBK, Shackleton CM & Witkowski ETF (2007). Conceptualizing the human use of wild edible herbs for conservation in South African communal areas. Journal of Environmental Management 84:146-156.

[33] Ndengejeho HM (2007). Linking household wealth and resource use: A case study in the Agincourt, rural district of South Africa. MSc thesis. Johannesburg: University of the Witwatersrand.

[34] Kahn K, Tollman SM, Garenne M & Gear JSS (1999). Who dies from what? Determining cause of death in Africa’s rural north-east. Tropical Medicine and International Health 4: 433-441.

[35] Kahn K, Garenne ML, Collinson MA & Tollman SM (2007). Mortality trends in a new South Africa: Hard to make a fresh start. Scandinavian Journal of Public Health 35:26-34.

[36] Twine W & Hunter LM (2008). HIV/AIDS mortality and the role of woodland resources in the maintenance of household food security in a rural district of South Africa. Final Research Report. Johannesburg: RENEWAL.

Environmental change in Bushbuckridge

[1] Farina A (2000). The cultural landscape as a model for the integration of ecology and economics. Bioscience 50:313-320.

[2] Shackleton C (2003). The prevalence of use and value of wild edible herbs in South Africa: research in action. South African Journal of Science 99, 1-2:23-25.

[3] Giannecchini M, Twine W & Vogel C (2007). Land-cover change and human-environment interactions in a rural cultural landscape in South Africa. The Geographical Journal 173, 1: 26-42.

[4] Asner GP, Knapp DE, Kennedy-Bowdoin RE, Jones MO, Martin RE, Boardman J & Field CB (2007). Carnegie Airborne Observatory: in-flight fusion of hyperspectral imaging and waveform light detection and ranging (wLiDAR) for three-dimensional vegetation studies. Journal of Applied Remote Sensing 1: 013536.

[5] Twine W, Moshe D & Siphugu M (2003). Harvesting of communal resources by ‘outsiders’ in rural South Africa: A case of xenophobia or a real threat to sustainability? International Journal of Sustainable Development and World Ecology. 10:263-274.

Living with drought: Adaptation, alleviation and monitoring

[1] Subrahmanyam VP (1967). Incidence and spread of continental drought: World Meteorological Organization, International Hydrological Decade, Reports on WMO/IHD Projects, no. 2. Geneva: Switzerland.

Climate change: Risks, adaptation and sustainability

[1] Leichenko RM & O’Brien K (2008). Environmental change and globalization, double exposures. Oxford: Oxford University Press.

[2] United Nations Office for the Co-ordination of Humanitarian Affairs (OCHA ) (2009). Flood/Cyclone Situation Update [online]. Available from: http://ochalonline.un.org/rosa/humanitarian situations.

[3] Boko M, Niang I, Nyong A, Vogel C, Githeko A, Medany M, Osman-Elasha B, Tabo R & Yanda P (2007). Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change: Africa. In Parry ML, Canziani OF, Palutikof JP, Van der Linden PJ & Hanson CE (eds) Climate Change 2007: Impacts, adaptation and vulnerability, 433-467. Cambridge: Cambridge University Press.

[4] Dilley M (2005). Natural Disaster Hotspots: A global Risk Analysis, Disaster Risk Management Series, No. 5. Washington: World Bank and Columbia University.

[5] Bhavnani R, Vordsorgbe S, Owor M & Bousquet F (2008). Report on the Status of Disaster Risk Reduction in the Sub-Saharan Africa Region. Commission of the African Union, ISDR United Nations International Strategy for Disaster Risk Reduction, The World Bank.

[6] Benson C & Clay E (1995). The Impact of Drought on Sub-Saharan Economies: A Preliminary Examination. ODI Working Paper 77. London: Overseas Development Institute.

[7] Tadross MA, Jack C & Hewitson B (2005). On RCM-based projections of change in southern Africa summer climate. Geophysical Research Letter [online], 32 (1), L23713, DOI:10.1029/2005GL024460.

[8] DiMP, Disaster Mitigation for Sustainable Livelihoods Programme (2005). Severe storm post flood assessment. (Report prepared for the Directorate Transport, Roads and Stormwater, City of Cape Town.) Cape Town: University of Cape Town.

[9] DiMP (2008). Weathering the Storm: Participatory risk assessment of informal settlements. Cape Town: PeriPeri publications, University of Cape Town.

[10] Holloway A, Fortune G & Chasi V (In press). RADAR Western Cape Risk and Development Annual Review. Disaster Mitigation for Sustainable Livelihoods Programme.

[11] Adger WN, Paavola J, Huq S & Mace MJ (2006). Fairness in adaptation to climate change. Cambridge, Massachusetts: Massachusetts Institute of Technology.

[12] Barnett J (2006). Climate change, insecurity and injustice. In Adger WN, Paavola J, Huq S & Mace MJ (eds) Fairness in adaptation to climate change, 115-129. Cambridge, Massachusetts: Massachusetts Institute of Technology.

[13] Kolmannskog VO (2008). Future floods of refugees, a comment on climate change, conflict and forced migration. Oslo: Norwegian Refugee Council, Norway.

[14] German Advisory Council on Global Change (2007). Climate change as a security risk. London: WBGU.

[15] Mitchell T, Haynes K, Hall N, Choong W & Oven K (2008). The role of children and youth in communicating disaster risk. Children, Youth and Environments 18, 1:254-279.

[16] Save the Children (2008). In the Face of Disaster: Children and climate change. Cambridge House, London: International Save the Children Alliance.

[17] UNICEF (2008). Our climate, our children, our responsibility. The implications of climate change for the world’s children. London: UNICEF, UK.

[18] Vogel C & O’Brien K (2006). Who can eat Information? Examining the effectiveness of seasonal climate forecasts and regional climate-risk management strategies. Climate Research 33: 111-122.

[19] Hewitson B (2009). University of Cape Town, Personal Communication.

[20] Vogel C, Moser S, Kasperson R & Daebelko G (2007). Linking Vulnerability, Adaptation and Resilience Science to Practice: Pathways, Players and Partnerships. Global Environmental Change 17:349-364.

SECTION 2 – ATMOSPHERIC SYSTEM AND CLIMATIC CHANGESAir pollution and the interactions between atmosphere, biosphere and the anthroposphere.

[1] Scorgie et al. (2002). Air Pollution in the Vaal Triangle – Quantifying source contributions and identifying cost-effective Solutions. NACA 2002 Conference Proceedings, Sasolburg.

[2] Ramanathan V & Carmichael G (2008). Global and regional climate changes due to black carbon. Nature Geoscience 1:221-227.

[3] Laakso L, Laakso H, Aalto PP, Keronen P, Petäjä T, Nieminen T, Pohja T, Siivola E, Kulmala M, Kgabi N, Phalatse D, Molefe M, Mabaso D, Pienaar JJ & Kerminen V-M (2008). Basic characteristics of atmospheric particles, trace gases and meteorology in a relatively clean Southern African Savannah environment. Atmospheric Chemistry and Physics 8:4823-4839.

REFERENCES 285

[4] Stull RB (1988). Introduction to Boundary layer Meteorology. Dordrecht: Kluwer Academic Publishers.

[5] Garstang M, Tyson PD, Swap R, Edwards RM, Kallberg P & Lindesay JA (1996). Horizontal and vertical transport of air over southern Africa. Journal of Geophysical Research 101, 23: 777-791.

[6] South African Weather Service (2009). [online] Available at: http://www.saws.co.za.

[7] Boko M, Niang I, Nyong A, Vogel C, Githeko A, Medany M, Osman-Elasha B, Tabo R & Yanda P (2007). Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change: Africa. In Parry ML, Canziani OF, Palutikof JP, Van der Linden PJ & Hanson CE (eds) Climate Change 2007: Impacts, Adaptation and Vulnerability, 433-467. Cambridge: Cambridge University Press.

The South African Air Quality Information System (SAAQIS)

[1] Department of Environmental Affairs and Tourism (2007). The 2007 National Framework for Air Quality Management in the Republic of South Africa. Government Gazette 30057 of 11 September 2007, Notice No. 830.

[2] Ravenscroft G (2009). A Baseline Audit, Assessment and Status Report on Government’s Current Ambient Air Quality Monitoring Activities. Draft Report. Pretoria: Department of Environmental Affairs and Tourism.

Marion Island’s disappearing ice cap

[1] McDougall I, Verwoerd W & Chevalier L (2001). K-Ar geochronology of Marion Island, Southern Ocean. Geological Magazine 138:1-17.

[2] Verwoerd WJ (1971). Geology. In Van Zinderen Bakker EM, Winterbottom JM & Dyer RA (eds) Marion and Prince Edward Islands. Report on the South African Biological and Geological Expedition 1965-1966, 40-53. Cape Town: A.A. Balkema.

[3] Hall K (1982). Rapid deglaciation as an initiator of volcanic activity: an hypothesis. Earth Surface Processes and Landforms 7:45-51.

[4] Hall K (1990). Quaternary Glaciations in the Southern Ocean: Sector 0° Long.–180° Long. Quaternary Science Reviews 9:217-228.

[5] Boelhouwers JC, Meiklejohn KI, Holness S & Hedding DW (2008). Geology, Geomorphology and Climate Change. In Chown SL & Froneman PW (eds) The Prince Edward Islands. Land-sea interactions in a changing ecosystem, 65-96. Stellenbosch: African Sun Media.

[6] Sumner PD, Meiklejohn KI, Boelhouwers JC & Hedding DW (2004). Climate change melts Marion Island’s snow and ice. South African Journal of Science 100:395-398.

[7] Van Zinderen Bakker EM, Winterbottom JM & Dyer RA (eds) (1971). Marion and Prince Edward Islands. Report on the South African Biological and Geological Expedition 1965-1966. Cape Town: A.A. Balkema.

[8] Verwoerd WJ, Russell S & Berruti A (1981). 1980 volcanic eruption reported on Marion Island. Earth and Planetary Science Letters 54: 397-422.

Climate change, species and ecosystems: Why systematic observation is critical for a predictive understanding of South African ecosystems and biodiversity

[1] Solomon S, Qin D, Manning M, Chen Z, Marquis M, Averyt KB, Tignor M & Miller HL (eds) (2007). Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge, United Kingdom: Cambridge University Press.

[2] Cowling RM, Rundel PW, Lamont BB, Arroyo MK & Arianoutsou M (1996). Plant diversity in Mediterranean-climate regions. Trends in Ecology & Evolution 11:362-366.

[3] Myers N, Mittermeier RA, Mittermeier CG, Da Fonseca GAB & Kent J (2000). Biodiversity hotspots for conservation priorities. Nature (London) 403:853-858.

[4] Erasmus BFN, Van Jaarsveld AS, Chown SL, Kshatriya M & Wessels KJ (2002). Vulnerability of South African animal taxa to climate change. Global Change Biology 8:679-693.

[5] Bond WJ & Midgley GF (2000). A proposed CO2-controlled mechanism of woody plant invasion in grasslands and savannas. Global Change Biology 6:865-869.

[6] Bond WJ, Midgley GF & Woodward FI (2003). The importance of low atmospheric CO2 and fire in promoting the spread of grasslands and savannas. Global Change Biology 9:973-982.

[7] Hulme M, Doherty R, Ngara T, New M & Lister D (2001). African climate change: 1900-2100. Climate Research 17:145-168.

[8] Thuiller W, Midgley GF, Hughes GO, Bomhard B, Drew G, Rutherford MC & Woodward FI (2006). Endemic species and ecosystem sensitivity to climate change in Namibia. Global Change Biology 12:759-776.

[9] Woodward FI & Lomas MR (2004). Simulating vegetation processes along the Kalahari transect. Global Change Biology 10:383-392.

[10] Mucina L & Rutherford MC (2006). The vegetation of South Africa, Lesotho and Swaziland. Strelitzia 19:1-808.

[11] Scholes RJ & Biggs R (2005). A biodiversity intactness index. Nature (London) 434:45-49.

[12] Hewitson BC & Crane RG (2006). Consensus between GCM climate change projections with empirical downscaling: Precipitation downscaling over South Africa. International Journal of Climatology 26:1315-1337.

[13] Broennimann O, Thuiller W, Hughes G, Midgley GF, Alkemade JMR & Guisan A (2006). Do geographic distribution, niche property and life form explain plants’ vulnerability to global change? Global Change Biology 12:1079-1093.

[14] Bomhard B, Richardson DM, Donaldson JS, Hughes GO, Midgley GF, Raimondo DC, Rebelo AG, Rouget M & Thuiller W (2005). Potential impacts of future land use and climate change on the Red List status of the Proteaceae in the Cape Floristic Region, South Africa. Global Change Biology 11:1452-1468.

[15] Midgley GF, Hannah L, Millar D, Thuiller W & Booth A (2003). Developing regional and species-level assessments of climate change impacts on biodiversity in the Cape Floristic Region. Biological Conservation 112:87-97.

[16] Williams P, Hannah L, Andelman S, Midgley GF, Araujo M, Hughes G, Manne L, Martinez-Meyer E & Pearson R (2005). Planning for climate change: Identifying minimum-dispersal corridors for the Cape Proteaceae. Conservation Biology 19:1063-1074.

[17] Bond WJ, Woodward FI, Midgley GF (2005). The global distribution of ecosystems in a world without fire. New Phytologist 165, 2:525-537.

[18] Higgins SI, Bond WJ, February EC, Bronn A, Euston-Brown DIW, Enslin B, Govender N, Rademan L, O’Regan S, Potgieter ALF, Scheiter S, Sowry R, Trollope L, Trollope WSW (2007). Effects of four decades of fire manipulation on woody vegetation structure in Savanna. Ecology 88, 5:1119-1125.

[19] Scheiter S, Higgins SI (2009). Impacts of climate change on the vegetation of Africa: an adaptive dynamic vegetation modelling approach. Global Change Biology 15, 9: 2224-2246.

[20] Midgley GF & Van der Heyden F (1999). Growth form and function: Perennial plants. In Dean RJ & Milton SJ (eds) The Karoo: Ecological patterns and processes, 91-106. Cambridge, UK: Cambridge University Press.

[21] Musil CF, Schmiedel U & Midgley GF (2005). Lethal effects of experimental warming approximating a future climate scenario on southern African quartz-field succulents: a pilot study. New Phytologist 165:539-547.

[22] Motete N, Midgley GF & Pammenter N (2005). Impact of elevated CO2 on the phenology and canopy structure of a C4 grassland microcosm. South African Journal of Botany 70:797-803.

[23] Wand SJE, Midgley GF & Stock WD (2000). Growth responses to elevated CO2 in NADP-ME, NAD-ME and PCK C4 grasses and a C3 grass from Africa. Australian Journal of Plant Physiology 28:13-25.

[24] Wand SJE, Midgley GF & Stock WD (2002). Response to elevated CO2 from a natural spring in C4-dominated grassland depends on seasonal phenology. African Journal of Range and Forage Science 19:81-91.


[25] Stock WD, Ludwig F, Morrow C, Midgley GF, Wand SJE, Allsopp N & Bell TL (2005). Long-term effects of elevated atmospheric CO2 on species composition and productivity of a southern African C4-dominated grassland in the vicinity of a CO2 exhalation. Plant Ecology 178:211-224.

[26] Foden W, Midgley GF, Hughes G, Bond WJ, Thuiller W, Hoffman MT, Kaleme P, Underhill LG, Rebelo A & Hannah L (2007). A changing climate is eroding the geographical range of the Namib Desert tree Aloe through population declines and dispersal lags. Diversity and Distribution 13:645-653.

[27] Ogutu JO & Owen-Smith N (2003). ENSO, rainfall and temperature influences on extreme population declines among African savanna ungulates. Ecology Letters 6:412-419.

SECTION 3 – STATES AND TRENDS IN THE TERRESTRIAL ENVIRONMENT

RANGELANDSChanges in rangeland capital: Trends, drivers and consequences

[1] Dean WRJ & Milton SJ (2003). Did the flora match the fauna? Acocks and historical changes in Karoo biota. South African Journal of Botany 69:68-78.

[2] Beinart W (2003). The rise of conservation in South Africa: Settlers, livestock and the environment 1770-1950. New York: Oxford University Press.

[3] Roux E (1946). The veld and the future. Cape Town: The African Bookman.

[4] O’Connor TG (2005). Influence of land use on plant community composition and diversity in Highland Sourveld grassland in the southern Drakensberg, South Africa. Ecology 42:975-988.

[5] Hoffman MT & Ashwell A (2001). Nature Divided: Land degradation in South Africa. Cape Town: University of Cape Town Press.

[6] Snyman HA & Van Rensburg WLJ (1986). Effect of slope and plant cover on runoff, soil loss and water use efficiency. Journal of the Grassland Society of Southern Africa 3:153-158.

[7] Shaw J (1875). On the changes going on in the vegetation of S.A. through the introduction of the Merino sheep. Journal of the Linnean Society 14:202-208.

[8] Acocks JPH (1953). Veld types of South Africa. Memoirs of the Botanical Survey of South Africa 28:1-192.

[9] Talbot WJ (1961). Land utilization in the arid regions of southern Africa. Part I. South Africa. In Stamp LD (ed) A history of land use in arid regions. Arid zones research 17:299-338. Paris: UNESCO.

[10] Milton SJ & Dean WRJ (1995). South Africa’s arid and semi-arid rangelands: why are they changing and can they be restored? Environmental monitoring and assessment 37: 245-264.

[11] Dean WRJ & Macdonald IAW (1994). Historical changes in stocking rates of domestic livestock as a measure of semi-arid and arid rangeland degradation in the Cape Province, South Africa. Journal of Arid Environments 26: 281-298.

[12] Steinschen AK, Görne A & Milton SJ (1996). Threats to the Namaqualand flowers: outcompeted by grass or exterminated by grazing? South African Journal of Science 92: 237-242.

[13] O’Connor TG & Roux PW (1995). Vegetation changes (1949-71) in a semi-arid, grassy dwarf shrubland in the Karoo, South Africa: influence of rainfall variability and grazing by sheep. Journal of Applied Ecology 32:612-626.

[14] Van der Berg L & Kellner K (2005). Restoring degraded patches in a semi-arid rangeland of South Africa. Journal of Arid Environments 61: 497-511.

[15] Mills AJ & Cowling RM (2006). Rate of carbon sequestration at two thicket restoration sites in the Eastern Cape, South Africa. Restoration Ecology 14:38-49.

[16] Danckwerts JE & Marais JB (1989). An evaluation of the economic viability of commercial pastoralism in the Smaldeel area of the Eastern Cape. Journal of the Grassland Society of southern Africa 6:1-7.

[17] Nel E & Hill T (2008). Marginalisation and demographic change in the semi-arid Karoo, South Africa. Journal of Arid Environments 72: 2264-2274.

Long-term changes in the vegetation of southern Africa as revealed by repeat photography: ‘A picture is worth a thousand words’

[1] Shantz HL & Turner BL (1958). Photographic documentation of vegetational changes in Africa over a third of a century. (Report no. 169:1-158). University of Arizona, College of Agriculture.

[2] Tiffen M, Mortimore M & Gichuki F (1994). More people, less erosion: Environmental recovery in Kenya. Chichester: John Wiley & Sons.

[3] Rohde RF (1997). Looking into the past: Interpretations of vegetation change in Western Namibia based on matched photography. Dinteria 25:121-149.

[4] Nyssen J, Munro N, Haile M, Poesen J, Deschee-maeker K, Haregeweyn N, Moeyersons J, Govers G & Deckers J (2007). Understanding the environmental changes in Tigray: a photographic record over 30 years. Tigray Livelihoods Papers no. 3. VLIR-Mekelle University IUC Programme: Zala-Daget Project.

[5] Hoffman MT & O’Connor TG (1999). Vegetation change over 40 years in the Weenen/Muden area, KwaZulu-Natal: evidence from photo-panoramas. African Journal of Range & Forage Science 16, 2&3:71-88.

[6] Midgley GF, Rutherford MC, Bond WJ & Barnard P (2008). The heat is on: Impacts of climate change on plant diversity in South Africa. Pretoria: South African National Biodiversity Institute.

[7] Hoffman MT & Rohde RF (2007). The historical impact of changing land use practices in Namaqualand. Journal of Arid Environments 70:641-658.

[8] Rohde RF & Hoffman MT (2008). One hundred years of separation: The historical ecology of a South African ‘Coloured Reserve’. Africa 78, 2:189-222.

Bush encroachment in southern African savannas

[1] Jacobs N (2000). Grasslands and thickets: bush encroachment and herding in the Kalahari Thornveld. Environment and History 6:289-316.

[2] Hudak AT & Wessman CA (2001). Textural analysis of high resolution imagery to quantify bush encroachment in Madikwe Game Reserve, South Africa, 1955-1996. International Journal of Remote Sensing 22:2731-2740.

[3] Wiseman R, Page BR & O’Connor TG (2004). Woody vegetation change in response to browsing in Ithala Game Reserve, South Africa. South African Journal of Wildlife Research 34:25-37.

[4] Wigley B, Bond WJ & Hoffman MT (2009). Bush encroachment under three contrasting land-use practices in a mesic South African savanna. African Journal of Ecology 47:62-70.

[5] Hoffman MT & Ashwell A (2001). Nature divided: Land degradation in South Africa. Cape Town, South Africa: University of Cape Town Press.

[6] Wiegand K, Ward D & Saltz D (2005). Multi-scale patterns and bush encroachment in an arid savanna with a shallow soil layer. Journal of Vegetation Science 16:311-320.

[7] Wiegand K, Saltz D & Ward D (2006). A patch dynamics approach to savanna dynamics and bush encroachment – insights from an arid savanna. Perspectives in Plant Ecology, Evolution and Systematics 7:229-242.

[8] Ward D (2009). The biology of deserts. Oxford: Oxford University Press.

[9] Roques KG, O‘Connor TG & Watkinson AR (2001). Dynamics of shrub encroachment in an African savanna: Relative influences of fire, herbivory, rainfall and density dependence. Journal of Applied Ecology 38:268-280.

[10] Britz ML & Ward D (2007). Dynamics of woody vegetation in a semi-arid savanna, with a focus on bush encroachment. African Journal of Range and Forage Science 24:131-140.

[11] Kraaij T & Ward D (2006). Effects of rain, nitrogen, fire and grazing on tree recruitment and early survival in bush-encroached savanna. Plant Ecology 186:235-246.

REFERENCES 287

[12] Eckhardt HC, Van Wilgen BW & Biggs HC (2000). Trends in woody vegetation cover in the Kruger National Park, South Africa, between 1940 and 1998. African Journal of Ecology 38: 108-115.

[13] Higgins SI, Bond WJ & Trollope WSW (2000). Fire, resprouting and variability: A recipe for tree-grass coexistence in savanna. Journal of Ecology 88:213-229.

[14] Bond WJ (2009). What Limits Trees in C4 Grasslands and Savannas? Annual Review of Ecology, Evolution and Systematics 39:641-659.

[15] Ward D (2005). Do we understand the causes of bush encroachment in African savannas? African Journal of Range and Forage Science 22: 101-105.

[16] Meyer K, Ward D, Moustakas A & Wiegand K (2005). Big is not better: small Acacia mellifera shrubs are more vital after fire. African Journal of Ecology 43:131-136.

[17] Jeltsch F, Milton SJ, Dean WRJ, Van Rooyen N & Moloney KA (1998). Modelling the impact of small-scale heterogeneities on tree-grass coexistence in semi-arid savannas. Journal of Ecology 86:780-794.

[18] Walter H (1939). Grassland, Savanne und Busch der arideren Teile Afrikas in ihrer Okologischen Bedingheit. Jahrbuch fur Wissenschaftliche Botanik 87:750-860.

[19] Smet M & Ward D (2006). Soil quality gradients around water-points under different management systems in a semi-arid savanna, South Africa. Journal of Arid Environments 64: 251-269.

[20] Hendricks HH, Bond WJ, Midgley JJ & Novellie PA (2007). Biodiversity conservation and pastoralism-reducing herd size in a communal livestock production system in Richtersveld National Park. Journal of Arid Environments 70:717-728.

[21] Jeltsch F, Milton SJ, Dean WRJ & Van Rooyen N (1997). Simulated pattern formation around artificial water holes in the semi-arid Kalahari. Journal of Vegetation Science 8:177-188.

[22] Sinclair ARE & Fryxell JM (1985). The Sahel of Africa: Ecology of a disaster. Canadian Journal of Zoology 63:987-994.

[23] Ward D (2010). A resource-ratio model of the effects of elevated CO2 on woody plant encroachment. Plant Ecology 209:147-152.

[24] Archer S, Schimel DS & Holland EA (2005). Mechanisms of shrubland expansion – land-use, climate or CO2? Climate Change 29:91-99.

[25] Walker BH, Ludwig D, Holling CS & Peterman RM (1981). Stability of semi-arid savanna grazing systems. Journal of Ecology 69: 473-498.

[26] Knoop WT & Walker BH (1985). Interactions of woody and herbaceous vegetation in a southern African savanna. Journal of Ecology 73: 235-253.

[27] Meyer KM, Wiegand K, Ward D & Moustakas A (2007). The rhythm of savanna patch dynamics. Journal of Ecology 95:1306-1315.

[28] Jeltsch F, Weber G & Grimm V (2000). Buffering mechanisms in savannas: A unifying theory of long-term tree-grass coexistence. Plant Ecology 150:161-171.

[29] Kaphengst T & Ward D (2008). Effects of habitat structure and shrub encroachment on bird species diversity in arid savanna in Northern Cape province, South Africa. Ostrich 79:133-140.

[30] Meik JM, Jeo RM, Mendelson JR & Jenks KE (2002). Effects of bush encroachment on an assemblage of diurnal lizard species in central Namibia. Biological Conservation 106:29-36.

[31] Ward D, Ngairorue BT, Samuels R & Ofran Y (1998). Land degradation is not a necessary outcome of communal pastoralism in arid Namibia. Journal of Arid Environments 40: 357-371.

Detecting inter-annual variability in the phenological characteristics of southern Africa’s vegetation using satellite imagery

[1] Schwartz MD (2003). Phenology: an integrative environmental science. Dordrecht: Kluwer Academic Publishers.

[2] Myneni R et al. (1997). Increased plant growth in northern high latitudes from 1981-1991. Nature 386:698-702.

[3] Reed BC (2006). Trend analysis of time-series phenology of North America derived from satellite data. GIScience & Remote Sensing 43: 1-15.

[4] Hewitson BC & Crane RG (2006). Consensus between GCM climate change projections with empirical downscaling: precipitation downscaling over South Africa. International Journal of Climatology. DOI:10.1002/joc.1314.

[5] Jonsson P & Eklundh L (2004). TIMESAT – a program for analyzing time-series of satellite sensor data. Computers and Geosciences 30: 833-845.

[6] Rutherford MC, Mucina L & Powrie LW (2006). Biomes and bioregions of Southern Africa. In Mucina L & Rutherford MC (eds) The vegetation of South Africa, Lesotho and Swaziland, 32-50. Cape Town: Strelitzia.

[7] Wessels KJ et al. (2007). Relevance of non-equilibrium theory to rangeland degradation in semiarid northeastern South Africa. Ecological Applications 17:815-827.

[8] Mucina L, Rutherford MC & Powrie LW (2006). The logic of the map: approaches and procedures. In Mucina L & Rutherford MC (eds) The vegetation of South Africa, Lesotho and Swaziland, 14-18. Cape Town: Strelitzia.

Impact of ENSO events on the Kruger National Park’s vegetation

[1] Reason CJC & Jagadheesha D (2005). A model investigation of recent ENSO impacts over southern Africa. Meteorology and Atmospheric Physics 89:181-205.

[2] Anyamba A, Tucker CJ & Mahoney R (2002). From El Niño to La Niña: Vegetation response pattern over East and Southern Africa during the 1997-2000 Period. Journal of Climate 15: 3096-3103.

[3] Wessels KJ, Prince SD, Zambatis N, MacFadyen S, Frost PE & Van Zyl D (2006). Relationship between herbaceous biomass and 1-km2 Advanced Very High Resolution Radiometer (AVHRR) NDVI in Kruger National Park, South Africa. International Journal of Remote Sensing 27:951-973.

[4] Smit IPJ & Grant CC (In press). Managing surface-water in a large semi-arid savanna park: Effects on grazer distribution patterns. Journal for Nature Conservation. DOI:10.1016/j.jnc.2009.01.001.

[5] Walker BH, Emslie RH, Owen-Smith N & Scholes RJ (1987). To cull or not to cull: lessons from a southern African drought. Journal of Applied Ecology 24:381-401.

[6] Parker AH & Witkowski ETF (1999). Long-term impacts of abundant perennial water provision for game on herbaceous vegetation in a semi-arid African savanna woodland. Journal of Arid Environment 41:309-321.

[7] Van Wilgen BW, Govender N, Biggs HC, Ntsala D & Funda XN (2004). Response of savanna fire regimes to changing fire-management policies in a large African national park. Conservation Biology 18:1535-1540.

[8] Giannecchini M, Twine W & Vogel C (2007). Usable science: an assessment of long-term seasonal forecast amongst farmers in rural areas of South-Africa. The Geographical Journal 173: 26-42.

[9] Vogel C (2000). Usable science: an assessment of long-term seasonal forecast amongst farmers in rural areas of South-Africa. South African Geographical Journal 82:107-116.

Assessing degradation across a land-use gradient in the Kruger National Park area using advanced remote sensing modalities

[1] Hoffman MT, Todd S, Ntoshona Z & Turner S (1999). Land degradation in South Africa. Cape Town: National Botanical Institute.

[2] Wessels KJ, Prince SD, Carroll M & Malherbe J (2007). Relevance of rangeland degradation in semiarid northeastern South Africa to the nonequilibrium theory. Ecological Applications 17:815-827.

[3] Wessels K, Prince SD, Malherbe J, Small J, Frost PE & Van Zyl D (2007). Can human-induced land degradation be distinguished from the effects of rainfall variability? – A case study in South Africa. Journal of Arid Environments 69:271-297.


[4] Higgins SI, Shackleton CM & Robinson ER (1999). Changes in woody community structure and composition under contrasting landuse systems in a semi-arid savanna, South Africa. Journal of Biogeography 26:619-627.

[5] Baltsavias EP (1999). Airborne laser scanning: Basic relations and formulas. ISPRS Journal of Photogrammetry and Remote Sensing 54:199-214.

Monitoring land degradation with long-term satellite data

[1] UNCCD (1994). United Nations Convention to combat desertification in countries experiencing serious drought and/or desertification, particularly in Africa. A/AC.241/27. Paris.

[2] Acocks JPH (1953).The veld types of South Africa. Memoirs of the Botanical Survey of South Africa 8:1-192.

[3] Dean WRJ et al. (1995). Desertification in the semiarid Karoo, South-Africa – review and reassessment. Journal of Arid Environments 30: 247-264.

[4] Hoffman MT et al. (1999). Land degradation in South Africa. Cape Town: National Botanical Institute.

[5] Hoffman MT & Ashwell A (2001). Nature divided: Land degradation in South Africa. Cape Town: Cape Town University Press.

[6] Fairbanks DHK et al. (2000). The South African land-cover characteristics database: a synopsis of the landscape. South African Journal of Science 96:69-82.

[7] Prince SD (2002). Spatial and temporal scales of measurement of desertification. In Stafford-Smith M & Reynolds JF (eds) Global desertification: do humans create deserts? 23-40. Berlin: Dahlem University Press.

[8] Wessels KJ et al. (2004). Assessing the effects of human-induced land degradation in the former homelands of northern South Africa with a 1 km AVHRR NDVI time-series. Remote Sensing of Environment 91:47-67.

[9] Wessels KJ et al. (2007). Relevance of rangeland degradation in semiarid northeastern South Africa to the non-equilibrium theory. Ecological Applications 17, 3:815-827.

[10] Shackleton CM (1993). Are the communal grazing lands in need of saving? Development South Africa 10:65-78.

[11] Wessels KJ et al. (2007). Can human-induced land degradation be distinguished from the effects of rainfall variability? A case study in South Africa. Journal of Arid Environments 68: 271-297.

Using models to predict the probability of degradation of rangelands when subjected to different management strategies

[1] Anon (1923). Final report of the drought investigation commission. Cape Town: Government Printer.

[2] Acocks JPH (1988). Veld types of South Africa. 3rd ed. Memoirs of the Botanical Survey of South Africa 57. Pretoria: Botanical Research Institute.

[3] Dean WRJ & MacDonald IAW (1994). Historical changes in stocking rates of domestic livestock as a measure of semi-arid and arid rangeland degradation in the Cape Province, South Africa. Journal of Arid Environments 26: 281-298.

[4] Milton SJ & Dean WRJ (1996). Karoo veld: Ecology and management. East Lynne: ARC Range and Forage Institute.

[5] Scoones I (1993). Why are there so many animals? Cattle population dynamics in the communal areas of Zimbabwe. In Behnke RH, Scoones I & Kerven C (eds) Range Ecology at Disequilibrium: New Models of Natural Variability and Pastoral Adaptation in African Savannas. London: Overseas Development Institute.

[6] Vetter S, Bond WJ & Trollope WSW (1998). How does one assess the costs of degradation in South African communal rangelands. In De Bruyn TD & Scogings PF (eds) Communal rangelands in southern Africa: A synthesis of knowledge. Fort Hare: Department of Livestock and Pasture Science, University of Fort Hare.

[7] Hoffman MT, Cousins B, Meyer T, Petersen A & Hendricks H (1999). Historical and contemporary land use and the desertification of the Karoo. In Dean WRJ & Milton SJ (eds) The Karoo: ecological patterns and processes, 257-273. Cambridge: Cambridge University Press.

[8] Dye PJ & Spear PT (1982). The effects of bush clearing and rainfall variability on grass yield and composition in South West Zimbabwe. Zimbabwe Journal of Agricultural Research 20:| 103-118.

[9] Biot Y (1993). How long can high stocking densities be sustained? In Behnke RH, Scoones I & Kerven C (eds) Range Ecology at Disequilibrium: New Models of Natural Variability and Pastoral Adaptation in African Savannas. London: Overseas Development Institute.

[10] Weigand T, Jeltsch F, Bauer S & Kellner K (1998). Simulation models for semi-arid rangelands of Southern Africa. African Journal of Range and Forage Science 15:48-60.

[11] Richardson FD & Hahn BD (2007). A short-term mechanistic model of forage and livestock in the semi-arid Succulent Karoo: 1. Description of the model and sensitivity analyses. Agricultural System 95:49-61.

[12] Hahn BD, Richardson FD, Hoffman MT, Roberts R, Todd SW & Carrick PJ (2005). A simulation model of long-term climate, livestock and vegetation interactions on communal rangelands in the semi-arid Succulent Karoo, Namaqualand, South Africa. Ecological Modelling 183:211-230.

[13] Richardson FD, Hahn BD & Hoffman MT (2007). Modelling the productivity and sustainability of pastoral systems in the communal areas of Namaqualand. Journal of Arid Environments 70:701-717.

[14] Hahn BD, Richardson FD & Starfield AM (1999). Frame-based modelling as a method of simulating rangeland production systems in the long term. Agricultural Systems 62:29-99.

Case studies in capital intensive crops towards system modelling of ecosystems using integrated hyperspectral remote sensing and in situ inputs

[1] Cho MA (2007). Hyperspectral remote sensing of biochemical and biophysical parameters: The derivative red-edge ‘double-peak feature’, a nuisance or an opportunity? Wageningen: Wageningen University.

[2] Cho MA, Van Aardt JAN, Main R & Majeke B (In press). Evaluating variations of physiology-based hyperspectral features along a soil water gradient in Eucalyptus grandis plantations. International Journal of Remote Sensing.

[3] Van Aardt JAN & Norris-Rogers M (2008). Spectral-age interactions in managed, even-aged Eucalyptus plantations: Application of discriminant analysis and classification and regression trees approaches to hyperspectral data. International Journal of Remote Sensing 29:1841-1845.

[4] Delalieux S, Van Aardt JAN, Keulemans W, Schrevens E & Coppin P (2007). Detection of biotic stress (Venturia inaequalis) in Apple trees using hyperspectral data: non-parametric statistical approaches and physiological implications. European Journal of Agronomy 27:130-143.

[5] Somers B, Delalieux S, Verstraeten WW, Vanden Eynde A & Coppin P (Submitted). The contribution of the fruit component to the integrated hyperspectral canopy signal. Photogrammetric Engineering and Remote Sensing.

[6] Kender WJ (2003). Citrus. HortiScience 38: 1043-1047.

INVASIVE ALIEN SPECIESTowards a predictive understanding of invasion success

[1] Williamson M & Fitter A (1996). The varying success of invaders. Ecology 77:1661-1666.

[2] Hobbs RJ & Humphries SE (1995). An integrated approach to the ecology and management of plant invasions. Conservation Biology 9:761-770.

[3] Reichard SH & Hamilton CW (1997). Predicting invasions of woody plants introduced in North America. Conservation Biology 11: 193-203.

[4] Lodge DM (1993). Biological invasions: lessons for ecology. Trends in Ecology and Evolution 8: 133-137.

REFERENCES 289

[5] Higgins SI & Richardson DM (1998). Pine invasion in the Southern hemisphere: modelling interaction between organism, environment and disturbance. Plant Ecology 135:79-93.

[6] Rejmánek M & Richardson DM (1996). What attributes make some plant species more invasive? Ecology 77:1655-1661.

[7] Menges ES (1998). Population viability analyses in plants: challenges and opportunities. Trends in Ecology and Evolution 15:51-56.

[8] Shaffer ML (1981). Minimum population sizes for species conservation. BioScience 31:131-134.

[9] Simberloff D (1988). The contribution of population and community biology to conservation science. Annual Review of Ecology and Systematics 19:473-511.

[10] Carlton JT (1996). Pattern, process and prediction in marine invasion ecology. Biological Conservation 78:97-106.

[11] Rouget M & Richardson DM (2003). Inferring process from pattern in plant invasions: a semi-mechanistic model incorporating propagule pressure and environmental factors. American Naturalist 162:713-724.

[12] Lockwood JL, Cassey P & Blackburn T (2005). The role of propagule pressure in explaining species invasions. Trends in Ecology and Evolution 20:223-228.

[13] Turnbull LA, Crawley MJ & Rees M (2000). Are plant population seed limited? A review of seed sowing experiments. Oikos 88:225-238.

[14] Iponga DM, Milton SJ & Richardson DM (2009a). Reproduction potential and seedling establishment of the invasive alien tree Schinus molle (Anacardiaceae) in South Africa. Austral Ecology 34:678-687.

[15] Wilson JRU, Richardson DM, Rouget M, Procheş Ş, Amis MA, Henderson L & Thuiller W (2007). Residence time and potential range: crucial considerations in modelling plant invasions. Diversity Distributions 13:11-22.

[16] Blumenthal DM (2006). Interactions between resource availability and enemy release in plant invasion. Ecology Letters 9:887-895.

[17] Davis MA, Grime JP & Thompson K (2000). Fluctuating resources in plant communities: a general theory of invasibility. Journal of Ecology 88:528-534.

[18] Elton CS (1958). The ecology of invasions by animals and plants. London: Metheun.

[19] Drake JA (1990). The mechanics of community assembly and succession. Journal of Theoretical Biology 147:213-233.

[20] Brown RL & Peet RK (2003). Diversity and invisibility of southern Appalachian plant communities. Ecology 84:32-39.

[21] Milton SJ & Hall AV (1981). Reproductive biology of Australian acacias in the S.W. Cape. Transactions of the Royal Society of South Africa 44:465-487.

[22] Iponga DM, Milton SJ & Richardson DM (2009b). Soil type, microsite, and herbivory influence growth and survival of Schinus molle (Peruvian pepper tree) invading semi-arid African savanna. Biological Invasion 11:159-169.

[23] Dewalt SJ, Denslow JS & Ickes K (2004). Test of the release from natural enemies hypothesis using the invasive tropical shrub Clidemia hirta. Ecology 85:71-483.

[24] Richardson DM, Allsopp N, D’Antonio CM, Milton SJ & Rejmánek M (2000). Plant invasions − the role of mutualisms. Biological Reviews of the Cambridge Philosophical Society 75:65-93.

[25] Hetrick BAD, Wilson GT & Hartnett DC (1989). Relationship between mycorrhizal dependence and competitive ability of two tallgrass prairie grasses. Canadian Journal of Botany 67:2608-2615.

[26] Robinson D & Fitter A (1999). The magnitude and control of carbon transfer between plants linked by a common mycorrhizal network. Journal of Experimental Botany 50:9-13.

[27] Milton SJ, Wilson JRU, Richardson DM, Seymour CL, Dean WRJ, Iponga DM & Procheş Ş (2007). Invasive alien plants infiltrate bird-mediated shrub nucleation processes in arid savanna. Journal of Ecology 95, 4:648-661.

[28] Iponga DM, Milton SJ & Richardson DM (2008). Superiority in competition for light: a crucial attribute of the invasive alien tree Schinus molle (Peruvian pepper tree) in shaping its impact in semi-arid South African savanna. Journal of Arid Environments 72:612-623.

[29] Belsky AJ, Mwonga SM, Amundson RG, Duxbury JM & Ali AR (1993). Comparative effects of isolated trees on their undercanopy environments in high- and low rainfall savannas. Journal of Applied Ecology 30:143-155.

[30] Pausas JG, Bonet A, Fernando T, Maestre FT & Climent A (2006). The role of the perch effect on the nucleation process in Mediterranean semi-arid oldfields. Acta Oecologica 29:346-352.

Are invasive aliens a real threat to biodiversity in South Africa?

[1] Noss RF (1990). Indicators for monitoring biodiversity: A hierarchical approach. Conservation Biology 4:355-364.

[2] Scholes RJ & Biggs R (2004). Ecosystem services in southern Africa: a regional assessment. Pretoria: CSIR.

[3] Van Wilgen BW & Richardson DM (2010). Current and future consequences of invasions: A case study from South Africa. In Perrings C, Mooney H & Williamson M (eds) Bioinvasions and Globalization: Ecology, Economics, Management and Policy, 183-201. Oxford: Oxford University Press.

[4] Goldblatt P & Manning J (2002). Plant diversity of the Cape region of South Africa. Annals of the Missouri Botanical Garden 89: 281-302.

[5] Richardson DM, Van Wilgen BW, Higgins SI, Trinder-Smith TH, Cowling RM & McKelly DH (1996). Threats to plant biodiversity on the Cape Peninsula, South Africa. Biodiversity and Conservation 5:607-647.

[6] Van Wilgen BW, Reyers B, Le Maitre DC, Richardson DM & Schonegevel L (2008). A biome-scale assessment of the impact of invasive alien plants on ecosystem services in South Africa. Journal of Environmental Management 89:336-349.

[7] Bruton MN (1995). Have fishes had their chips? The dilemma of threatened fishes. Environmental Biology of Fishes 43:1-27.

[8] Cowx IG (2002). Analysis of threat to freshwater fish populations: past and present challenges. In Collares-Pereira MJ, Cowx IG & Coelho MM (eds) Conservation of freshwater fishes: options for the future, 201-220. London: Fishing News Books.

[9] Tweddle D, Bills R, Swartz E, Coetzer W, Da Costa L, Engelbrecht J, Cambray J, Marshall B, Impson D, Skelton PH, Darwall WRT & Smith KS (2009). The status and distribution of freshwater fishes. In Darwall WRT, Smith KS, Tweddle D & Skelton P (eds) The status and distribution of freshwater biodiversity in Southern Africa, 21-37. Gland, Switzerland: IUCN.

[10] Impson ND, Bills IR & Cambray JA (2002). A conservation plan for the unique and highly threatened freshwater fishes of the Cape Floral Kingdom. In Collares-Pereira MJ, Cowx IG & Coelho MM (eds) Conservation of freshwater fishes: options for the future, 432-442. London: Fishing News Books.

[11] Roberts J & Tilzey R (1997). Controlling carp: exploring the options for Australia. Canberra, Australia: CSIRO Land and Water.

[12] Samways MJ & Taylor S (2004). Impacts of invasive alien plants on Red-Listed South African dragonflies (Odonata). South African Journal of Science 100:78-80.

[13] McChonnachie AJ, De Wit MP, Hill MP & Byrne MJ (2003). Economic evaluation of control of Azolla filiculoides in South Africa. Biological Control 28:25-32.

[14] Spinage C (2003). Rinderpest: A history. New York: Kluwer Academic.

[15] Coetzer JW & Tustin RW (2004). Infectuous diseases of livestock. 2nd ed. Vol. 2. Oxford: Oxford University Press.


Defining appropriate responses for addressing the increasing trade in alien species: The case of reptiles

[1] Kraus F (2009). Invading Nature – Springer Series in Invasion Ecology 4: Alien Reptiles and Amphibians – a Scientific Compendium and Analysis. Dordrecht: Springer.

[2] Van Wilgen NJ, Elith J, Wilson JR, Wintle BA & Richardson DM (In press). Alien invaders and reptile traders: What drives the live animal trade in South Africa? Animal Conservation. DOI:10.111/j.1469-1795.2009.00298.x.

[3] Auliya M (2003). Hot trade in cool creatures: A review of the live reptile trade in the European Union in the 1990s with a focus on Germany. TRAFFIC Europe. Brussels, Belgium.

[4] Van Wilgen NJ, Richardson DM & Baard EHW (2008). Alien reptiles and amphibians in South Africa: Towards a pragmatic management strategy. South African Journal of Science 104:13-20.

[5] Meshaka WEJ, Butterfield BP & Hauge JB (2004). The exotic amphibians and reptiles of Florida. Malabar, Florida: Krieger Publishing Company.

[6] South African Press Association (2008). SA man gets year in jail for smuggling rare animals. Cape Times, Cape Town, 10 December 2008.

[7] Bomford M, Kraus F, Barry SC & Lawrence E (2009). Predicting establishment success for alien reptiles and amphibians: a role for climate matching. Biological Invasions 11:713-724.

[8] Van Wilgen NJ, Roura-Pascual N & Richardson DM (2009). A quantitative climate-match score for risk-assessment screening of reptile & amphibian introductions. Environmental Management 44:590-607.

[9] Procheş Ş, Wilson JRU, Richardson DM & Rejmanek M (2008). Searching for phylogenetic pattern in biological invasions. Global Ecology and Biogeography 17:5-10.

South Africa’s southern sentinel: Terrestrial environmental change at sub-Antarctic Marion Island

[1] Bergstrom DM, Lucieer A, Kiefer K, Wasley J, Belbin L, Pedersen TK & Chown SL (2009). Indirect effects of invasive species removal devastate World Heritage Island. Journal of Applied Ecology 46:73-81.

[2] Chown SL & Froneman PW (2008). The Prince Edward Islands. Land-sea interactions in a changing ecosystem. Stellenbosch: African Sun Media.

[3] Lee JE, Janion C, Marais E, Jansen van Vuuren B & Chown SL (2009). Physiological tolerances account for range limits and abundance structure in an invasive slug. Proceedings of the Royal Society of London B 276:1459-1468.

[4] Le Roux PC & McGeoch MA (2008). Rapid range expansion and community reorganisation in response to warming. Global Change Biology 14:2590-2962.

[5] Bergstrom D & Chown SL (1999). Life at the front: history, ecology and change on southern ocean islands. Trends in Ecology and Evolution 14:472-477.

Species-level classification using imaging spectroscopy for the detection of invasive alien species

[1] Versfeld DB, Le Maitre DC & Chapman RA (1998). Alien invading plants and water resources in South Africa: a preliminary assessment (Report no. TT 99/98). Pretoria: Water Research Commission.

[2] Henderson L (1998). Southern African Plant Invaders Atlas (SAPIA). Applied Plant Science 12:31-32.

[3] Franklin SE (1994). Discrimination of subalpine forest species and canopy density using digital CASI, SPOT PLA and Landsat TM data. Photogrammetric Engineering & Remote Sensing 60:1233-1241.

[4] Martin ME, Newman SD, Aber JD & Congalton RG (1998). Determining forest species composition using high spectral resolution remote sensing data. Remote Sensing of Environment 65, 3:249-254.

[5] Fung T, Ma FY & Sui WL (1999). Hyperspectral Data analysis for subtropical tree species identification. Geocarto International 16, 3:25-36.

[6] Van Aardt JAN & Wynne RH (2001). Spectral separability among six southern tree species. Photogrammetric Engineering & Remote Sensing 67:1367-1375.

[7] Van Aardt JAN & Wynne RH (2007). Examining pine spectral separability using hyperspectral data from an airborne sensor: An extension of field-based results. International Journal of Remote Sensing 28, 1-2:431-436.

[8] Goodwin N, Turner R & Merton R (2005). Classifying Eucalyptus forests with high spatial and spectral resolution imagery: an investigation of individual species and vegetation communities. Australian Journal of Botany 53, 4:337-345.

MININGIntroduction

[1] Miller D (2007). Pre-European mining in South Africa. In Anonymous Deep South Africa. A celebration of the South African mining industry, Chapter 3. Cape Town: Nelida Publishing.

[2] Feinstein CH (2005). An economic history of South Africa: Conquest, discrimination and development. Cambridge: Cambridge University Press.

Overview of mining types, spatial distribution, costs and benefits

[1] Friede HM (1980). Iron Age mining in the Transvaal. Journal of the South African Institute for Mining and Metallurgy 80:156-165.

[2] Hammel A, White C, Pfeiffer S & Miller D (2000). Pre-colonial mining in southern Africa. Journal of the South African Institute for Mining and Metallurgy 100:49-56.

[3] Robb LJ & Robb VM (1998). Gold in the Witwatersrand basin. In Wilson MGC & Anhaeusser CR (eds) The mineral resources of South Africa, 294-349. Pretoria: Council for Geoscience.

[4] Wilson MGC & Anhaeusser CR (eds) (1998). The mineral resources of South Africa. Pretoria: Council for Geoscience.

[5] Meredith M (2007). Diamonds, gold and war. The making of South Africa. Johannesburg: Simon and Schuster, Jonathan Ball.

[6] Anon, Undated. Desktop-reports, 6. South Africa [online]. WWW.desktop.org.za.

[7] Lynn MD (1998). Diamonds. In Wilson MGC & Anhaeusser CR (eds) The mineral resources of South Africa, 232-258. Pretoria: Council for Geoscience.

[8] Roux PL (1998). Aggregates. In Wilson MGC & Anhaeusser CR (eds) The mineral resources of South Africa, 40-47. Pretoria: Council for Geoscience.

[9] Annandale JG, Beletse YG, Stirzaker RJ & Bristow KL (This volume). Managing poor quality coal-mine water: Is irrigation part of the solution?

[10] Wilson MGC, Robb VM, Robb LJ, Tosen GR, Conlin JB & Viljoen MJ (1998). Mining in South Africa: legislation and environmental considerations. In Wilson MGC & Anhaeusser CR (eds) The mineral resources of South Africa, 11-20. Pretoria: Council for Geoscience.

[11] Burke A (2005). Best practice guidelines for minimizing impacts on the flora of the southern Namib. Windhoek: Enviroscience, Namibia and Namibian Nature Foundation.

[12] Shillington K (1985). The colonisation of the Southern Tswana: 1870-1900. Johannesburg: Raven Press.

[13] MMSD (Mining and Minerals Sustainable Development Project) (2002). Report of the workshop on indigenous peoples. (Report no. 218). Perth, Australia: International Institute for Environment and Development (IIED).

[14] Milton SJ (2001). Rethinking ecological rehabilitation in arid and winter rainfall regions of southern Africa. South African Journal of Science 97:47-48.

REFERENCES 291

[15] Carrick PJ & Kruger R (2007). Restoring degraded landscapes in lowland Namaqualand: Lessons from the mining experience and from regional ecological dynamics. Journal of Arid Environments 70:767-781.

[16] Van Aarde RJ, Coe M & Niering WA (1996). On the rehabilitation of the coastal dunes of KwaZulu-Natal. South African Journal of Science 92:122-124.

[17] Van Aarde RJ, Wassenaar TD & Guldemond RAR (This volume). Restoring the mined coastal sand dunes of KwaZulu-Natal.

[18] Van Eeden JD, Lubke RA & Haarhoff P (2007). Return of natural, social and financial capital to the hole left by mining. In James AJ, Milton SJ & Blignaut JN (eds) Restoring natural capital: Science, business and practice, 198-207. Covalo, USA: Island Press.

Restoring the mined coastal sand dunes of KwaZulu-Natal

[1] Van Aarde RJ, Coe M & Niering WA (1996). On the rehabilitation of the coastal dunes of KwaZulu-Natal. South African Journal of Science 92:122-124.

[2] Van Wyk AE & Smith GF (2001). Maputaland Centre. In Van Wyk AE & Smith GF (eds) Regions of floristic endemism in southern Africa: a review with emphasis on succulents, 86-94. Pretoria, South Africa: Umdaus Press.

[3] For more information visit http://www.ceru.up.ac.za.

[4] Van Aarde RJ, Ferreira SM, Kritzinger JJ, Van Dyk PJ, Vogt M & Wassenaar TD (1996). An evaluation of habitat rehabilitation on coastal dune forests in northern KwaZulu-Natal, South Africa. Restoration Ecology 4:334-345.

[5] Wassenaar TD, Van Aarde RJ, Pimm SL & Ferreira SM (2005). Community convergence in disturbed subtropical dune forests. Ecology 86:655-666.

[6] Van Aarde RJ, Smit A-M & Claassens AS (1998). Soil characteristics of rehabilitating and unmined coastal dunes at Richards Bay, KwaZulu-Natal, South Africa. Restoration Ecology 6:102-110.

Coal mining on the Highveld and its implications for future water quality in the Vaal River system

Additional Reading

[1] Bell FG, Bullock SET, Hälbich TFJ & Lindsay P (2001). Environmental impacts associated with an abandoned mine in the Witbank coalfield, South Africa. DOI:10.1016/S0166-5162(00)00033-1.

[2] Bell FG, Hälbich TFJ & Bullock SET (2002). The effects of acid mine drainage from an old mine in the Witbank coalfield. Quarterly Journal of Engineering Geology and Hydrology 356: 265-278.

[3] Hodgson FDI & Krantz RM (1998). Investigation into groundwater quality deterioration in the Olifants River catchment above Loskop Dam with specialized investigation in the Witbank Dam sub-catchment. (Report no. 291/1/98). Pretoria: Water Research Commission.

[4] Mentis MT (2006). Restoring native grassland on land disturbed by coal mining on the Eastern Highveld of South Africa. South African Journal of Science 102:193-197.

[5] Pinetown KL, Ward CR & Van der Westhuizen WA (2007). Quantitative evaluation of minerals in coal deposits in the Witbank and Highveld coalfields, and the potential impact on acid mine drainage. International Journal of Coal Geology 70: 166-183.

Managing poor quality coal-mine water: Is irrigation part of the solution?

[1] Younger PL & Wolkersdorfer C (2004). Mining impacts on the fresh water environments: Technical and managerial guidelines for catchment scale management. Mine Water and the Environment 23:S2-S80.

[2] Thompson JG (1980). Acid mine waters in South Africa and their amelioration. Water SA 6:130-134.

[3] Annandale JG, Beletse YG, De Jager PC, Jovanovic NZ, Steyn JM, Benadé N, Lorentz SA, Hodgson FDI, Usher B, Vermeulen PD & Aken ME (2007). Predicting the environmental impact and sustainability of irrigation with coal-mine water. (Report no. 1149/01/07). Pretoria: Water Research Commission.

[4] Grobbelaar R, Usher B, Cruywagen LM, De Necker E & Hodgson FDI (2004). Long-term impact of intermine flow from collieries in the Mpumalanga area. (Report no. 1056/1/04). Pretoria: Water Research Commission.

[5] Pulles W (2006). Management options for mine water drainage in South Africa. In WISA, mine water division (ed) Mine water drainage-South African perspective, 19-20. Johannesburg: Water Institute of Southern Africa (WISA).

[6] Du Plessis HM (1983). Using lime treated acid mine water for irrigation. Water Science and Technology 15:145-154.

[7] Annandale JG, Jovanovic NZ, Claassens AS, Benadé N, Lorentz SA, Johnston MA, Tanner PD, Aken ME & Hodgson FDI (2001). The influence of irrigation with gypsiferous mine water on soil properties and drainage water. (Report no. K5/858). Pretoria: Water Research Commission.

[8] Vermeulen PD, Usher BH & Van Tonder GJ (2008). Determining of the impact of coal mine water irrigation on groundwater resources. (Report no. 1507/1/08). Pretoria: Water Research Commission.

[9] Annandale JG, Jovanovic NZ, Hodgson FDI, Usher B, Aken ME, Van der Westhuizen AM, Bristow KL & Steyn JM (2006). Prediction of the environmental impact and sustainability of large-scale irrigation with gypsiferous mine-water on groundwater resources. Water SA 32, 1:21-28.

SECTION 4 – STATES AND TRENDS IN THE AQUATIC ENVIRONMENT

FRESHWATER AND ESTUARINE SYSTEMSEstuaries and global change: With an emphasis on the ichthyofauna

[1] Whitfield AK (2000). Available scientific information on individual South African estuarine systems. (Report no. 577/3/00). Pretoria: Water Research Commission.

[2] Wallace JH, Kok HM, Beckley LE, Bennett B, Blaber SJM & Whitfield AK (1984). South African estuaries and their importance to fishes. South African Journal of Science 80:203-207.

[3] Turpie J, Winkler H, Spalding-Fecher R & Midgley G (2002). Economic impacts of climate change in South Africa: A preliminary analysis of unmitigated damage costs. (Unpublished Report, 1-58). Southern Waters and Energy and Development Research Centre.

[4] DEAT (1999). National State of the Environment Report – South Africa: Marine and Coastal Systems and Resources [online]. Available from: http://www.environment.gov.za/soer/ [Accessed March 2009].

[5] Turpie JK (2004). South African National Spatial Biodiversity Assessment 2004. Estuary Component. (Technical Report no. 3). Pretoria: South African National Biodiversity Institute.

[6] Morant PD & Quinn NW (1999). Influence of Man and management of South African estuaries. In Allanson BR & Baird D (eds) Estuaries of South Africa, 289-320. Cambridge: Cambridge University Press.

[7] Field CB, Osborn JG, Hoffman LL, Polensberg JF, Ackerly DD, Berry JA, Bjorkman O, Held A, Matson PA & Mooney HA (1998). Mangrove biodiversity and ecosystem function. Global Ecology and Biogeography Letters 7:3-14.

[8] Rajkaran A, Adams JB & Du Preez DR (2004). A method for monitoring mangrove harvesting at the Mngazana estuary, South Africa. African Journal of Aquatic Science 29:57-65.

[9] Adam P (2002). Saltmarshes in a time of change. Environmental Conservation 29:39-61.


[10] Gilman EL, Ellison J, Duke NC & Field C (2008). Threats to mangroves from climate change and adaptations options: A review. Aquatic Botany 89:237-250.

[11] IPCC (2007). Summary for policy makers. In Solomon S, Qin D, Manning M, Chen Z, Marquis M, Averyt KB, Tignor M & Miller HL (eds) Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge, United Kingdom and New York, NY, USA: Cambridge University Press.

[12] Harley CDG, Hughes AR, Hultgren KM, Miner BG, Sorte CJB, Thornber CS, Rodriguez LF, Tomanek L & Williams SL (2006). The impacts of climate change in coastal marine systems. Ecology Letters 9: 228-241.

[13] WWF (2009). Taking care of our estuaries: why and how [online]. Available from: http://www.iwrm.co.za/ [Accessed March 2009].

Estuarine fish communities in hot water?

[1] Schumann EH, Cohen AL & Jury MR (1995). Coastal sea surface temperature variability along the south coast of South Africa and the relationship to regional and global climate. Journal of Marine Research 53:231-248.

[2] Combes S (2005). Are we putting our fish in hot water? WWF, Switzerland.

[3] Clark BM (2006). Climate change: A looming challenge for fisheries management in southern Africa. Marine Policy 30:84-95.

[4] Maree RC, Whitfield AK & Booth AJ (2000). Effect of water temperature on the biogeography of South African estuarine fish species associated with the subtropical/warm temperate subtraction zone. South African Journal of Science 96:184-188.

[5] Harrison TD (2005). Ichthyofauna of South African estuaries in relation to the zoogeography of the region. Smithiana 6:2-27.

[6] James NC, Whitfield AK & Cowley PD (2008). Preliminary indications of climate-induced change in a warm-temperate South African estuarine fish community. Journal of Fish Biology 72:1855-1863.

[7] Heemstra P & Heemstra E (2004). Coastal fishes of southern Africa. Grahamstown: Nisc.

[8] Smith MM & Heemstra PC (1990). Smith’s sea fishes. Johannesburg: Southern Book Publishers.

[9] Kruger AC & Shongwe S (2004). Temperature trends in South Africa: 1960-2003. International Journal of Climatology 24:1929-1945.

[10] Branch GM & Grindley JR (1979). Ecology of southern African estuaries Part XI. Mngazana: A mangrove estuary in the Transkei. South African Journal of Zoology 14:149-170.

[11] Mbande S, Whitfield AK & Cowley PD (2005). The ichthyofaunal composition of the Mngazi and Mgazana estuaries: a comparative study. Smithiana Bulletin 4:1-22.

[12] Baron JS, Joyce LA, Kareiva P, Keller BD, Palmer MA, Peterson CH & Scott JM (2008). Preliminary review of adaptation options for climate-sensitive ecosystems and resources. In Julius SH, West JM (eds) A Report by the U.S. Climate Change Science Program and the Subcommittee on Global Change Research. Washington DC, USA: U.S. Environmental Protection Agency.

[13] Skelton PH (1993). Freshwater fishes of southern Africa. Cape Town: Struik Publishers.

[14] Whitfield AK (1998). Biology and ecology of fishes in southern African estuaries. Icthyological Monographs of the J.L.B. Smith Institute of Ichthyology No. 2.

Changing patterns of freshwater fish diversity in South Africa

[1] Nel J, Maree G, Roux D, Moolman J, Kleynhans N, Silberbauer M & Driver A (1994). South African National Spatial Biodiversity Assessment 2004: Technical Report. Volume 2: River Component. (CSIR Report no. ENV-S-I-2004-063). Stellenbosch: Council for Scientific and Industrial Research.

[2] Scott LEP, Skelton PH, Booth AJ, Verheust L, Harris R & Dooley J (2006). Atlas of Southern African Freshwater Fishes. Smithiana Monograph 2, 303.

[3] Skelton PH (1994). Diversity and distribution of freshwater fishes in East and Southern Africa. Annals Museum Royale de l’Afrique Centrale 275:95-131.

[4] Tweddle D, Bills R, Swartz ER, Coetzer W, Da Costa L, Engelbrecht J, Cambray JA, Marshall B, Impson D, Skelton PH, Darwall WRT & Smith KS (2009). The status and distribution of freshwater fishes. In Darwall WRT, Smith KG, Tweddle D & Skelton PH (eds) The status and distribution of freshwater biodiversity in Southern Africa, 21-37. Gland, Switzerland: IUCN, and Grahamstown, South Africa: SAIAB.

[5] Skelton PH (2001). A complete guide to the freshwater fishes of southern Africa. Struik: Cape Town.

[6] Thieme ML, Abell R, Stiassny MLJ, Skelton PH, Lehner B, Teugels GG, Dinerstein E, Toham AK, Burgess N & Olson D (eds) (2005). Freshwater ecoregions of Africa and Madagascar, a conservation assessment. Washington DC: Island Press.

[7] Skelton PH (1986). Fish of the Orange-Vaal system. In Davies BR & Walker KF (eds) The ecology of river systems, 43-162. Monographiae Biologicae 60. Dordrecht, The Netherlands: Dr W. Junk Publishers.

[8] Skelton PH, Cambray JA, Lombard A & Benn GA (1995). Patterns of distribution and conservation of freshwater fishes in South Africa. South African Journal of Zoology 30:71-81.

[9] Skelton PH (2002). An overview of the challenges of conserving freshwater fishes in South Africa. In Collares-Pereira MJ, Coelho MM & Cowx IG (eds) Conservation of freshwater fishes: Options for the future, 221-236. Oxford, UK: Fishing News Books.

[10] Rall JL (2005). Conservation of the Maloti minnow, Pseudobarbus quathlambae. (Final Report, Contract 1041). Maseru: Lesotho Highlands Development Authority.

[11] Swartz ER (2005). Phylogeography, phylogenetics and evolution of the redfins (Teleostei, Cyprinidae, Pseudobarbus) in southern Africa. PhD dissertation. Pretoria: University of Pretoria.

[12] Impson D (2008). The status of the Clanwilliam yellowfish. In Impson ND, Bills IR & Wolhuter L (eds) Technical Report on the state of yellowfishes in South Africa 2007, 15-30. (Report no. KV 212/08). Pretoria: Water Research Commission.

[13] Marr SM, Sutcliffe LME, Day JA, Griffiths CL & Skelton PH (2009). Conserving the fishes of the Twee River, Western Cape, South Africa: revisiting the issues. African Journal of Aquatic Sciences 34, 1:77-85.

[14] De Moor IJ & Bruton MN (1988). Atlas of alien and translocated indigenous aquatic animals in southern Africa. (Report no. 144). South African National Scientific Programmes.

[15] De Moor IJ (1997). Case studies of the invasion by four alien fish species (Cyprinus carpio, Micropterus salmoides, Oreochromis macrochir and Oreochromis mossambicus) of freshwater ecosystems in Southern Africa. Transactions of the Royal Society of South Africa 51:233-255.

[16] De Villiers P & Ellender B (2008). Status of the Orange-Vaal smallmouth yellowfish. In Impson ND, Bills IR & Wolhuter L Technical Report on the state of yellowfishes in South Africa 2007, 77-92. (Report no. KV 212/08). Pretoria: Water Research Commission.

[17] Cambray JA (2003). The need for research and monitoring on the impacts of translocated sharptooth catfish, Clarias gariepinus, in South Africa. African Journal of Aquatic Science 28, 2: 191-195.

[18] Hamman KCD, Thorne SC & Skelton PH (1984). The discovery of the Cape kurper, Sandelia capensis (Cuvier, in C&V, 1831) in the Olifants River system (Western Cape Province). The Naturalist 28:24-26.

[19] Swartz ER (2008). Managing translocations and alien populations of yellowfish and other large cyprinid species. In Impson ND, Bills IR & Wolhuter L Technical Report on the state of yellowfishes in South Africa 2007, 144-156. (Report no. KV 212/08). Pretoria: Water Research Commission.

[20] Abell R, Thieme ML, Revenga C, Bryer M, Kottelat M, Bogutskaya N, Coad B, Mandrak N, Contreras Balderas S, Bussing W, Stiassny MLJ, Skelton P, Allen GR, Unmack P, Naseka A, Ng R, Sindorf N, Robertson J, Armijo E, Higgins JV, Heibel TJ, Wikramanayake E, Olson D, Lopez HL, Reis RE, Lundberg JG, Sabaj Perez MH & Petry P (2008). Freshwater ecoregions of the world: A new map of biogeographic units for freshwater biodiversity conservation. Bioscience 58, 3:403-414.

REFERENCES 293

The impacts of afforestation on surface water resources

[1] Legat CE (1930). The cultivation of exotic conifers in South Africa. Empire Forestry Journal 6:32-63.

[2] Van der Zel DW & Brink M (1980). Die geskiedenis van bosbou in suider-Afrika. Deel II. Plantasiebosbou. South African Forestry Journal 115:17-27.

[3] Forestry and Forest Product Industry Facts (2008). Spreadsheet [online]. Available from: http://www.forestry.co.za/ [Accessed February 2009].

[4] Agricultural Research Council (ARC) & CSIR (2000). National Land Cover database and spatial data for 2000. Pretoria: Agricultural Research Council & CSIR.

[5] Midgley DC, Pitman WV & Middleton BJ (1994). The surface water resources of South Africa 1990, Vol. 1 to 6. (Report nos. 298/1.1/94 to 298/6.1/94 (text) and 298/1.2/94 to 298/6.2/94 (maps)). Pretoria: Water Research Commission. Also accompanied by a CD-ROM with selected data sets.

[6] Scott DF, Le Maitre DC & Fairbanks DHK (1998). Forestry and streamflow reductions in South Africa: A reference system for assessing extent and distribution. Water SA 24:187-199.

[7] Scott DF (2005). On the hydrology of industrial timber plantations. Hydrological Processes 19:4203-4206.

[8] Scott DF & Lesch W (1997). Streamflow responses to afforestation with Eucalyptus grandis and Pinus patula and to felling in the Mokobulaan experimental catchments, Mpumalanga province, South Africa. Journal of Hydrology 199:360-377.

[9] Le Maitre DC, Chapman RA & Versfeld DB (2000). The impact of invading alien plants on surface water resources in South Africa: A preliminary assessment. Water SA 26:397-408.

[10] Scott DF (1993). The hydrological effects of fire in South African mountain catchments. Journal of Hydrology 150:409-432.

[11] Wicht CL (1949). Forestry and water supplies in South Africa. (Bulletin no. 33). Pretoria: Department of Forestry.

[12] Wicht CL (1967). Forest hydrology research in the South African Republic. In Sopper E & Lull HW (eds) International Symposium on Forest Hydrology, 75-84. Oxford: Pergamon Press Ltd.

[13] Van der Zel DW (1995). Accomplishments and dynamics of the South African Afforestation Permit System. South African Forestry Journal 172:49-58.

[14] Dye PJ & Versfeld D (2007). Managing the hydrological impacts of South African plantation forests: An overview. Forest Ecology and Management 251:121-128.

[15] Gush MB, Scott DF, Jewitt GPW, Schulze RE, Lumsden TG, Hallowes LA & Görgens AHM (2002). Estimation of streamflow reductions resulting from commercial afforestation in South Africa. (Report no. TT 173/02). Pretoria: Water Research Commission.

[16] Republic of South Africa (1998). National Water Act, no. 36 of 1998. Pretoria: Government Printer.

[17] Forestry South Africa (2002). Environmental guidelines for commercial plantations in South Africa. 2nd ed. Rivonia, Johannesburg: Forestry Environmental Committee, Forestry South Africa.

[18] Republic of South Africa. Strategic Environmental Assessment. Pretoria: Department of Water Affairs and Forestry [online]. Available from: http://www.dwaf.gov.za/sfra/sea/SEA%20Background.asp.

[19] Republic of South Africa (2000). Strategic Environmental Assessment for Water Use. Mhlathuze Catchment – KZN. (Report no. SEA-01/2000). Pretoria: Department of Water Affairs and Forestry.

[20] Coastal and Environmental Services (2005). The development of a Strategic Environmental Assessment (SEA) for the zone of afforestation potential in the Eastern Cape. Pretoria: Department of Water Affairs and Forestry.

[21] Warburton M & Schulze R (2006). Climate change and the South African commercial forestry sector. An initial study. (ACRUcons Report 54) [online]. Available from: http://www.forestry.co.za/ [Accessed February 2009].

[22] Crickmay & Associates (2005). Study of supply and demand of industrial roundwood in South Africa. Pretoria: Department of Water Affairs.

[23] Water for Africa (2008). Afforestation potential in the Limpopo Province. (Report no. WP 9696). Pretoria: Department of Water Affairs and Forestry.

[24] Water for Africa (2009). Basic assessment of afforestation potential in KwaZulu-Natal and Mpumalanga Provinces. (Report no. WP 9706). Pretoria: Department of Water Affairs and Forestry.

The South African River Health Programme

[1] Roux DJ (1997). National Aquatic Ecosystem Biomonitoring Programme: Overview of the design process and guidelines for implementation. (NAEBP Report Series no. 6). Pretoria: Institute for Water Quality Studies, Department of Water Affairs and Forestry.

[2] The Freshwater Consulting Group (2007). Rivers Database for the National Aquatic Ecosystems Health Monitoring Programme (RHP). Pretoria: Department of Water Affairs and Forestry.

[3] Department of Water Affairs and Forestry (2008). National Aquatic Ecosystem Health Monitoring Programme (NAEHMP): River Health Programme (RHP) Implementation Manual. Version 2. Pretoria: Department of Water Affairs and Forestry.

A multi-temporal approach for identifying and mapping changes in wetlands using satellite imagery

[1] Mitsch WJ & Gosslink JG (1993). Wetlands. New York: Wiley and Sons.

[2] Elliot CR & Hektner MM (2000). Wetland Resources of Yellowstone National Park. Yellowstone National Park, Wyoming: National Park Service, Yellowstone National Park, Yellowstone Centre for Resources.

[3] Anderson VJ & Herdin PJ (1992). Infrared photo interpretation of non-riparian wetlands. Rangelands 14, 6:334-336.

[4] Lunetta RS & Balogh ME (1999). Application of multi temporal LANDSAT 5 TM imagery for wetland identification. Photogrammetric Engineering and Remote Sensing 65, 11: 1303-1310.

[5] Dini J, Cowan G & Goodman P (1998). South African National Wetland Inventory: Proposed Wetland Classification System for South Africa [online]. Available from: http://www.ccwr.ac.za/wetlands/inventory-classif.htm.

[6] Tarboton KC & Schulze RE (1992). Distributed hydrological modeling system for the Mgeni Catchment. (Report no. 234 /1/ 92). Pretoria: Water Research Commission.

[7] Johnston RM & Berson MM (1993). Remote sensing of Australian wetlands: An evaluation of LANDSAT TM data for inventory and classification. Australian Journal of Marine and Freshwater Research 44:235-252.

[8] Eastman RJ (1997). IDRISI User Guide: Guide to GIS and image processing, Vol. 2. Satellite Applications Center: Worster, USA.

[9] Environmental Systems Research Institute (ESRI) (1996). Arcview 3.2. Redlands, Ca., United States of America.

[10] Scotney DM (1970). Soil and land-use planning in the Howick Extension area. Unpublished PhD dissertation. Pietermaritzburg: University of Natal.

[11] SAC (1992). Wetland Classification System. Technical Report. Ahmedabad: Space Applications Centre (ISRO).

[12] Verhoeye JAC, Vancoille FMB, Nishimura DJH, De Wulf RR & Kerckoffs EJH (2000). Sub pixel classification of the Sahelian wetlands environment. South African Journal of Surveying and Geo-Information 1, 5&6:282-289.

MARINE INSHORE ENVIRONMENTClimate change, sea level rise and the southern African coastal zone: A general revue of causes, consequences and possible responses

[1] Rahmstorf S, Cazenave A, Church JA, Hansen JE, Keeling RF, Parker DE, Somerville RCJ (2007). Recent climate observations compared to projections. Science 316:709 [online]. Available from: http://www.sciencemag.org [Accessed 1 February 2007].


[2] IPCC (2007). Summary for policy makers. In Solomon S, Qin D, Manning M, Chen Z, Marquis M, Averyt KB, Tignor M & Miller HL (eds) Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge, United Kingdom and New York, NY, USA: Cambridge University Press.

[3] Mather AA (2008). Sea level rise for the East Coast of Southern Africa. (Paper no. M-04). Dubai, UAE: COPEDEC VII.

[4] Church JA & White NJ (2006). A 20th century acceleration in global sea-level rise. Geophysical Research Letters 33:L01602.

[5] Gregory JM (2004). Threatened loss of the Greenland ice-sheet. Nature 428, 616:257.

[6] Bentley CR (1997). Rapid sea-level rise soon from West Antarctic ice sheet collapse? Science 275, 5303:1077-1079.

[7] Thomas R, Rignot E, Casassa G, Kanagaratnam P, Acuña C, Akins T, Brecher H, Frederick E, Gogineni P, Krabill W, Manizade S, Ramamoorthy H, Rivera A, Russell R, Sonntag J, Swift R, Yungel Y & Zwally J (2004). Accelerated sea-level rise from West Antarctica.Science Magazine 8:255-258.

[8] Theron AK (2007). Analysis of potential coastal zone climate change impacts and possible response options in the southern African region. Proceedings IPCC TGICA Conference: Integrating Analysis of Regional Climate Change and Response Options, 205-216, June 2007. Nadi, Fiji.

[9] Tol RSJ (2004). The double trade-off between adaptation and mitigation for sea level rise: An application of FUND. FNU-48 (submitted), Research Unit Sustainability and Global Change, Hamburg University and Centre for Marine and Atmospheric Science.

[10] Arthurton R (2003). The fringing reef coasts of eastern Africa − Present processes in their long-term context. Western Indian Ocean Journal of Marine Science 2, 1:1-13.

Sea level rise and its anticipated impacts along the east coast of South Africa.

[1] Hobday DK & Jackson MPA (1979). Transgressive shore zone sedimentation and syndepositional deformation in the Pleistocene of Zululand, South Africa. Journal of Sedimentary Petrology 49, 1:0145-0158.

[2] Bindoff NL et al. (2007). Observations: Oceanic climate change and sea level. In Solomon S, Qin D, Manning M, Chen Z, Marquis M, Averyt KB, Tignor M & Miller HL (eds). Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, 385-432. Cambridge, United Kingdom and New York, NY, USA: Cambridge University Press.

[3] Mather AA (2007). Linear and non-linear sea-level changes at Durban, South Africa. South African Journal of Science 103, 11/12:509-512.

[4] Combrinck L (2008). Hartebeesthoek Radio Astronomy Observatory, Personal Communication.

[5] Pirazzoli PA (1996). Sea-level changes. The last 20 000 years. New York: Wiley.

[6] eThekwini Municipality (2009). Draft Report on Projections and Modeling Scenarios for Sea-level Rise at Durban, South Africa. Durban: eThekwini Municipality.

[7] Garland GG (2005). Coastal and shoreline geomorphology, and development recommendations for 299 Refinery Drive, Isipingo. Durban: School of Environmental Science, Geography, University of KwaZulu-Natal.

[8] Breetzke T, Paruk O, Celliers L, Mather AA & Colenbrader D (eds) (2008). Living with coastal erosion in KwaZulu-Natal. A short term, best practice guide. Pietermaritzburg: Department of Agriculture and Environmental Affairs.

[9] Republic of South Africa (2009). Integrated Coastal Management Act. Government Gazette 31884.

[10] Council for Scientific and Industrial Research (CSIR) (2008). Sand supply from rivers within the eThekwini jurisdiction, implications for coastal sand budgets and resource economics. (Report no. CSIR/NRE/ECO/ER/2008/0096/C). Pretoria: Council for Scientific and Industrial Research.

The 2006-2007 KwaZulu-Natal coastal erosion event in perspective

[1] Inman DL, Jenkins SA & Masters PM (2003). Modeling the future of sand beaches. OCEANS 2003 Proceedings 3, 1485-1486.

[2] Cooper JAG (1991a). Shoreline changes on the Natal coast: Mkomanzi River mouth to Tugela River mouth. (Report no. 77). Pietermaritzburg: Natal Town & Regional Planning Commission.

[3] Cooper JAG (1991b). Shoreline changes on the Natal coast: Tugela river mouth to Cape St Lucia. (Report no. 76). Pietermaritzburg: Natal Town & Regional Planning Commission.

[4] Cooper JAG (1994). Shoreline changes on the Natal coast: Mtamvuna River mouth to the Mkomazi River mouth. (Report no. 79). Pietermaritzburg: Natal Town & Regional Planning Commission.

[5] Pilkey H & Cooper JAG (2004). Society and sea level rise. Science 303:1781-1782.

[6] Alemaw BF & Chaoke TR (2006). The 1950-1998 warm ENSO events and regional implications to river flow variability in Southern Africa. Water SA 32, 4:459-463.

[7] Garland & Moleko (2000). Geomorphological impacts of Inanda on the Mgeni estuary, north of Durban, South Africa. Bulletin of Engineering Geology and the Environment 59:119-126.

[8] Smith AM, Guastella LA, Bundy S & Mather AA (2007). Combined marine storm and Saros spring-high tide erosion event, March 19-20, 2007: A preliminary assessment. South African Journal of Science 103:274-276.

[9] IPCC (2007). Summary for policy makers. Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [online]. Available from: http://www.ipcc.ch [Accessed 21 February 2007].

[10] Dingler JR & Reiss TR (2002). Changes to Monterey Bay beaches from the end of the 1982-83 El Niño through the 1997-98 El Niño. Marine Geology 181:249-263.

[11] Mather AA (2007). Linear and non-linear sea-level changes at Durban, South Africa. South African Journal of Science 103, 11/12:509-512.

[12] Bosman C, Smith AM & Uken R (2008). A sigmoidal shoreface-connected ridge field: Aliwal Shelf, KZN, South Africa. Paper presented at the 13th Southern African Marine Science Symposium (SAMS 2008), 29 June-3 July, Cape Town, University of Cape Town.

[13] Ematek (1992). Durban Offshore Wave Recording Quarterly Progress Report: Winter 1991. (Confidential CSIR Report EMAS-D 92001). Pretoria: Council for Scientific and Industrial Research.

[14] Rossow M. Personal communication, CSIR.

[15] SA Weather Service (1991). Caelum: A history of notable weather events in South Africa: 1500-1990. Pretoria: The Weather Bureau, Department of Environmental Affairs.

[16] Guastella LA, Smith AM, Mather AA & Bundy SC (2008). Post March 2007 marine storm erosion of KZN beaches. Paper presented at the 13th Southern African Marine Science Symposium (SAMS 2008), 29 June-3 July, Cape Town, University of Cape Town.

[17] Short AD (2002). Large scale behavior of topographically bound beaches. Proceedings of the 28th International Conference on Coastal Engineering, July 2002, Cardiff, Wales.

[18] McMahon JH, Thornton EB, Stanton TP & Reniers AJHM (2005). RIPEX: Observations of a rip current system. Marine Geology 218, 1-4:113-134.

REFERENCES 295

[19] Shand RD, Hesp PA & Shepherd MJ (2004). Beach cut in relation to net offshore bar migration. ICS 2004 Proceedings. Journal of Coastal Research SI 39 [online]. Available from: http://www.coastalsystems.co.nz/rogers_downloads/2004%20Shand%20Occational%20Papaer%202004_1.pdf.

[20] Thornton EB, MacMahan J & Sallenger AH Jr (2007). Rip currents, mega-cusps, and eroding dunes. Marine Geology 240:151-167.

Sea level rise for Cape Town: Impacts and adaptation

[1] Smith AM, Mather AA, Theron AK, Bundy SC & Guastella LA-M (In this publication). The 2006-2007 KwaZulu-Natal coastal erosion event in perspective.

Climate change and coastal upwelling: Potential implications for South African marine resources

[1] Lutjeharms JRE, Cooper J & Roberts M (2000). Upwelling at the inshore edge of the Agulhas Current. Continental shelf research 20: 737-761.

[2] Peterson WT, Arcos DF, McManus GB, Dam H, Bellantoni D, Johnson T & Tiselius P (1988). The nearshore zone during coastal upwelling: Daily variability and coupling between primary and secondary production off Central Chile. Progress in Oceanography 20:1-40.

[3] Daneri G, Dellarossa V, Quinones R, Jacob B, Montero P & Ulloa O (2000). Primary production and community respiration in the Humboldt Current System off Chile and associated oceanic areas. Marine Ecology Progress Series 197:41-49.

[4] Largier JL, Lawrence CA, Roughan M, Kaplan DM, Dever EP, Dorman CE, Kudela RM, Bollens SM, Wilkerson FP, Dugdale RC, Botsford LW, Garfield N, Kuebel Cervantes B & Koracin D (2006). WEST: A northern California study of the role of wind-driven transport in the productivity of coastal plankton communities. Deep-Sea Research II 53:2833-2849.

[5] Montecino V, Astoreca R, Alarcon G, Retamal L & Pizarro G (2004). Bio-optical characteristics and primary productivity during upwelling and non-upwelling conditions in a highly productive coastal ecosystem off central Chile (~36oS). Deep-Sea Research II 51:2413-2426.

[6] Pitcher GC, Bolton JJ, Brown PC & Hutchings L (1993). The development of phytoplankton blooms in upwelled waters of the southern Benguela upwelling system as determined by microcosm experiments. Journal of Experimental Marine Biology and Ecology 165:171-189.

[7] Simard Y, De Ladurantaye R & Therriault J-C (1986). Aggregation of euphausiids along a coastal shelf in an upwelling environment. Marine Ecology Progress Series 32:203-215.

[8] Bosman AL, Hockey PAR & Siegfried WR (1987). The influence of coastal upwelling on the functional structure of rocky intertidal communities. Oecologia 72:226-232.

[9] Bakun A (1990). Global climate change and intensification of coastal ocean upwelling. Science 247:198-201.

[10] Trenberth KE, Jones PD, Ambenje P, Bojariu R, Easterling D, Klein Tank A, Parker D, Rahimzadeh F, Renwick JA, Rusticucci M, Soden B & Zhai P (2007). Observations: surface and atmospheric climate change. In Solomon S, Qin D, Manning M, Chen Z, Marquis M, Averyt KB, Tignor M & Miller HL (eds) Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, 235-336. Cambridge, United Kingdom and New York, NY, USA: Cambridge University Press.

[11] Barth JA, Menge BA, Lubchenco J, Chan F, Bane JM, Kirincich AR, McManus MA, Nielsen KJ, Pierce SD & Washburn L (2007). Delayed upwelling alters nearshore coastal ocean ecosystems in the northern California current. PNAS 104:3719-3724.

[12] Botsford LW, Lawrence CA, Dever EP, Hastings A & Largier J (2003). Wind strength and biological productivity in upwelling systems: an idealized study. Fisheries Oceanography 12:245-259.

[13] Cole J (1999). Environmental conditions, satellite imagery, and clupeoid recruitment in the northern Benguela upwelling system. Fisheries Oceanography 8:25-38.

[14] Ings DW, Horne JK & Schneider DC (1997). Influence of episodic upwelling on capelin, Mallotus villosus, and Atlantic cod, Gadus morhua, catches in Newfoundland coastal waters. Fisheries Oceanography 6:41-48.

[15] Shannon LV, Crawford RJM, Brundrit GB & Underhill LG (1988). Responses of fish populations in the Benguela ecosystem to environmnental change. ICES Journal of Marine Science 45:1-12.

[16] Skogen MD (2005). Clupeoid larval growth and plankton production in the Benguela upwelling system. Fisheries Oceanography 14:64-70.

[17] Ward TM, McLeay LJ, Dimmlich WF, Rogers PJ, McClatchie S, Matthews R, Kämpf J & Van Ruth PD (2006). Pelagic ecology of a northern boundary current system: effects of upwelling on the production and distribution of sardine (Sardinops sagax), anchovy (Engraulis australis) and southern bluefin tuna (Thunnus maccoyii) in the Great Australian Bight. Fisheries Oceanography 15: 191-207.

[18] Yoo J-T, Nakata H & Sugimoto T (2004). Effect of horizontal advection induced by intrusion of the Kuroshio water on plankton biomass in the spring fishing period of shirasu on the Pacific coast of Japan. Fisheries Science 70:937-944.

[19] Rouault M, Penven P & Pohl B (2008). Warming in the Agulhas Current since the 80s. In 13th South African Marine Science Symposium. Cape Town.

[20] Escribano R, Daneri G, Farías L, Gallardo VA, González HE, Gutiérrez D, Lange CB, Morales CE, Pizarro O, Ulloa O & Braun M (2004). Biological and chemical consequences of the 1997-1998 El Niño in the Chilean coastal upwelling system: a synthesis. Deep-Sea Research II 51:2389-2411.

[21] Schumann EH, Cohen AL & Jury MR (1995). Coastal sea surface temperature variability along the south coast of South Africa and the relationship to regional and global climate. Journal of Marine Research 53:231-248.

[22] Shannon LV, Crawford RJM & Hutchings L (2008). Climate change and the Benguela: Fact or fiction. In Hempel G, O’Toole M & Sweijd N (eds) Currents of Plenty, 13-119. Cape Town: Benguela Currents Commission.

Using Marine Protected Areas as a tool for long-term monitoring of coastal marine biota

[1] Sauer WHH, Hecht T, Britz PJ & Mather D (2003). Economic and regulatory principles, survey results, transformation and socio-economic impact. In Mather D, Britz PJ, Hecht T & Sauer WHH (eds) Marine and coastal management, South Africa, 1-36. Grahamstown: Rhodes University.

[2] Garibaldi L, Lowther A, Csirke J, Crispoldi A, Smith A, Kelleher K, Doulman D, Hishamunda N, Subasinghe R, Bartley DM, Vannuccini S, Laurenti G & Josupeit H (2004). World review of fisheries and aquaculture. In Grainger R & Shehadeh Z (eds) The state of world fisheries and aquaculture. Rome, Italy: FAO Publishing.

[3] Jackson JBC, Kirby MX, Berger WH, Bjorndal KA, Botsford LW, Bourque BJ, Bradbury RH, Cooke R, Erlandson J, Estes JA, Hughes TP, Kidwell S, Lange CB, Lenihan HS, Pandolfi JM, Peterson CH, Steneck RS, Tegner MJ & Warner RR (2001). Historical overfishing and the recent collapse of coastal ecosystems. Science 293:629-638.

[4] Carr MH, Neigel JE, Estes JA, Andelman S, Warner RR & Largier JL (2003). Comparing marine and terrestrial ecosystems: implications for the design of coastal marine reserves. Ecological Applications 13:90-107.

[5] Huntsman GR (1994). Endangered marine finfish: neglected resources or beasts of fiction? Fisheries 19:8-15.

[6] Griffiths MH (2000). Long-term trends in catch and effort of commercial linefish off South Africa’s Cape Province: snapshots of the 20th century. South African Journal of Marine Science 22:81-110.


[7] Bohnsack JA (1993). Marine reserves: they enhance fisheries, reduce conflicts and protect resources. Oceanus 36:63-71.

[8] Ludwig D, Hilborn R & Walters C (1993). Uncertainty, resource exploitation, and conservation: lessons from history. Science 260:17-36.

[9] Roberts CM (1997). Ecological advice on the global fisheries crisis. Trends in Ecology and Evolution 12:35-38.

[10] Clark CW (1996). Marine reserves and the precautionary management of fisheries. Ecological Applications 6:369-370.

[11] Roberts CM, Bohnsack JA, Gell F, Hawkins JP & Goodridge R (2000). Effects of marine reserves on adjacent fisheries. Science 294: 1920-1923.

[12] Bohnsack JA & Ault JS (1996). Management strategies to conserve marine biodiversity. Oceanography 9:73-82.

[13] Guénette S & Pitcher TJ (1999). An age-structured model showing the benefits of marine reserves in controlling overexploitation. Fisheries Research 39:295-303.

[14] Gell FR & Roberts CM (2003). The fishery effects of marine reserves and fishery closures. Washington DC: World Wildlife Fund.

[15] Attwood CG, Mann BQ, Beaumont J & Harris JM (1997). Review of the state of marine protected areas in South Africa. South African Journal of Marine Science 18:341-367.

[16] Götz A, Cowley PD & Winker H (2008). Selected fishery and population parameters of eight shore-angling species in the Tsitsikamma National Park no-take marine reserve. African Journal of Marine Science 30:519-532.

Human activities as drivers of change on South African rocky shores

[1] Griffiths CL & Branch GM (1997). The exploitation of coastal invertebrates and seaweeds in South Africa: historical trends, ecological impacts and implications for management. Transactions of the Royal Society of South Africa 52:121-148.

[2] Hockey PAR, Bosman AL & Siegfried WR (1988). Patterns and correlates of shellfish exploitation by coastal people in Transkei: an enigma of protein production. Journal of Applied Ecology 25:353-363.

[3] Brouwer SL, Mann BQ, Lamberth SJ, Sauer WHH & Erasmus C (1997). A survey of the South Africa shore-angling fishery. South African Journal of Marine Science 18:165-177.

[4] Griffiths MH (2000). Long-term trends in catch and effort of commercial linefish off South Africa’s Cape Province: snapshots of the 20th Century. South African Journal of Marine Science 22:81-110.

[5] Griffiths CL, Van Sittert L, Best PB, Brown AC, Clark BM, Cook PA, Crawford RJM, David JHM, Davies BR, Griffiths MH, Hutchings K, Jeraldino A, Kruger N, Lamberth S, Leslie RW, Melville-Smith R, Tarr R & Van der Lingen CD (2004). Human impacts on marine animal life in the Benguela: a historical overview. Oceanography and Marine Biology. An Annual Review 42:303-392.

[6] Santelices B & Griffiths CL (1994). Seaweeds as resources. In Siegfried WR (ed) Rocky shores: Exploitation in Chile and South Africa, 33-55. Berlin: Springer.

[7] Stegenga H, Bolton JJ & Anderson RJ (1997). Seaweeds of the South African west coast. Contributions from the Bolus Herbarium 18: 1-655.

[8] Griffiths CL, Hockey PAR, Van Erkom Schurink C & Le Roux PJ (1992). Marine invasive aliens on South African shores: implications for community structure and trophic functioning. South African Journal of Marine Science. 12:713-722.

[9] Griffiths CL, Robinson TB & Mead A (2009). The status and distribution of marine alien species in South Africa. In Rilov G & Crooks JA (eds) Biological invasions in marine ecosystems. Ecological studies 204:393-408. Berlin, Heidelberg: Springer-Verlag.

[10] Robinson TB, Griffiths CL, McQuaid CD & Ruis M (2005). Marine alien species of South Africa – status and impacts. African Journal of Marine Science 27:297-306.

[11] Laird MC & Griffiths CL (2008). Present distribution and abundance of the introduced barnacle Balanus glandula Darwin in South Africa. African Journal of Marine Science 30: 93-100.

[12] Laroche RK, Kock AA, Dill LM & Oosthuizen WH (2007). Effects of provisioning ecotourism activity on the behaviour of white sharks Carcharodon carcharias. Marine Ecology Progress Series 338:199-209.

Seabirds: Sentinels of southern Africa’s seas

[1] Watkins BP, Petersen SL & Ryan PG (2008). Interactions between seabirds and deep-water hake trawl gear: an assessment of impacts in South African waters. Animal Conservation 11: 247-254.

[2] Crawford RJM (2007). Food, fishing and seabirds in the Benguela upwelling system. Journal of Ornithology 148 (Suppl 2): S253-S260.

[3] Pichegru L, Ryan PG, Van der Lingen CD, Coetzee J, Ropert-Coudert Y & Grémillet D (2007). Foraging behaviour and energetics of Cape gannets Morus capensis feeding on live prey and fishery waste in the Benguela upwelling system. Marine Ecology Progress Series 350: 127-136.

[4] Grémillet D, Pichegru L, Kuntz G, Woakes AG, Wilkinson S, Crawford RJM & Ryan PG (2008). A junk-food hypothesis for gannets feeding on fishery waste. Transactions of the Royal Society of London B 275:1149-1156.

[5] Crawford RJM, Underhill LG, Coetzee JC, Fairweather T, Shannon LJ & Wolfaardt AC (2008). Influences of the abundance and distribution of prey on African penguins Spheniscus demersus off western South Africa. African Journal of Marine Science 30:167-175.

[6] Crawford RJM, Tree AJ, Whittington PA, Visagie J, Upfold L, Roxburg KJ, Martin AP & Dyer BM (2008). Recent distributional changes of seabirds in South Africa: is climate having an impact? African Journal of Marine Science 30: 189-193.

[7] Crawford RJM, Makhado AB, Upfold L & Dyer BM (2008). Mass on arrival of rockhopper penguins at Marion Island correlated with breeding success. African Journal of Marine Science 30:185-188.

[8] Lewis S, Daunt F, Grémillet D, Ryan PG, Crawford RJM & Wanless S (2006). Individual behaviour and population growth rates in seabirds. Oecologia 147:606-614.

[9] Crawford RJM, Dundee BL, Dyer BM, Klages NTW, Meÿer MA & Upfold L (2007). Trends in numbers of Cape gannets (Morus capensis), 1956/57-2005/06, with a consideration of the influence of food and other factors. ICES Journal of Marine Science 64:169-177.

Causes and effects of changes in the distribution of anchovy and sardine in shelf waters off South Africa

[1] Van der Lingen CD, Shannon LJ, Cury P, Kreiner A, Moloney CL, Roux J-P & Vaz-Velho F (2006). Resource and ecosystem variability, including regime shifts, in the Benguela Current system. In Shannon V, Hempel G, Malanotte-Rizzoli P, Moloney C & Woods J (eds) Benguela: Predicting a large marine ecosystem. Large marine ecosystems 14, 147-185. Amsterdam: Elsevier.

[2] Fairweather TP, Hara M, Van der Lingen CD, Raakjaer J, Shannon LJ, Louw GG, Degnbol P & Crawford R (2006). A knowledge base for management of the capital-intensive fishery for small pelagic fish off South Africa. African Journal of Marine Science 28, 3&4:645-660.

[3] Cury P, Bakun A, Crawford RJM, Jarre-Teichmann A, Quinones RA, Shannon LJ & Verheye HM (2000). Small pelagics in upwelling systems: patterns of interaction and structural changes in ‘wasp-waist’ ecosystems. ICES Journal of Marine Science 57, 3:603-618.

[4] Barange M, Hampton I & Roel BA (1999). Trends in the abundance and distribution of anchovy and sardine on the South African continental shelf in the 1990s, deduced from acoustic surveys. South African Journal of Marine Science 21:367-391.

REFERENCES 297

[5] Roy C, Van der Lingen CD, Coetzee JC & Lutjeharms JRE (2007). Abrupt environmental shift associated with changes in the distribution of Cape anchovy Engraulis encrasicolus spawners in the southern Benguela. African Journal of Marine Science 29, 3:309-319.

[6] Pichegru L, Ryan PG, Van der Lingen CD, Coetzee JC, Ropert-Coudert Y & Gremillet D (2007). Foraging behaviour and energetics of Cape gannets Morus capensis feeding on live prey and fishery discards in the Benguela upwelling system. Marine Ecology Progress Series 350:127-136.

[7] Crawford RJM & Ryan PG (In this publication). Seabirds – sentinels of southern Africa’s seas.

[8] Coetzee JC, Van der Lingen CD, Hutchings L & Fairweather TP (2008). Has the fishery contributed to a major shift in the distribution of South African sardine? ICES Journal of Marine Science 65, 9:1676-1688.

[9] Fairweather TP, Van der Lingen CD, Booth AJ, Drapeau L & Van der Westhuizen JJ (2006). Indicators of sustainable fishing for South African sardine Sardinops sagax and anchovy Engraulis encrasicolus. African Journal of Marine Science 28, 3&4:661-680.

Large-scale shifts in the spatial distribution of West Coast rock lobster in South Africa

[1] Cockcroft A & Payne AIL (1999). A cautious fisheries management policy in South Africa: the fisheries for rock lobster. Marine Policy 23: 587-600.

[2] Cockcroft AC, Van Zyl D & Hutchings L (2008). Large-scale changes in the spatial distribution of South African West Coast rock lobsters: an overview. African Journal of Marine Science 30, 1:149-159.

[3] Pollock DE, Cockcroft AC & Goosen PC (1997). A note on reduced rock lobster growth rates and related environmental anomalies in the southern Benguela, 1988-1995. South African Journal of Marine Science 18:287-293.

[4] Cockcroft AC (2001). Jasus lalandii ‘walkouts’ or mass strandings in South Africa during the 1990s: an overview. Marine and Freshwater Research 52:1085-1094.

[5] Roy C, Van der Lingen CD, Coetzee JC & Lutjeharms JRE (2007). Abrupt environmental shift associated with changes in the distribution of Cape anchovy Engraulis encrasicolus spawners in the southern Benguela. African Journal of Marine Science 29, 3:309-319.

[6] Crawford RJM, Cockcroft AC, Dyer B & Upfold L (2008). Divergent trends in bank cormorants Phalacrocorax neglectus in South Africa’s Western Cape consistent with a distributional shift of rock lobsters Jasus lalandii. African Journal of Marine Science 30, 1:161-166.

[7] Field JG, Griffiths CL, Griffiths RJ, Jarman N, Zoutendyk P, Velimirov B & Bowes A (1980). Variation in structure and biomass of kelp communities along the south-west Cape coast. Transactions of the Royal Society of South Africa 44:145-203.

[8] Tarr RJQ, Williams PVG & Mackenzie L (1992). Abalone, sea urchins and rock lobster: a possible ecological shift that may affect traditional fisheries. South African Journal of Marine Science 17:319-323.

[9] Mayfield S & Branch G (2000). Interrelations among rock lobsters, sea urchins, and juvenile abalone: implications for community management. Canadian Journal of Fisheries Aquatic Science 57:2175-2185.

MARINE OFFSHORE ENVIRONMENTThe southern African oceans

[1] Lutjeharms JRE (2006). The Agulhas Current. Heidelberg: Springer-Verlag.

[2] Ansorge IJ & Lutjeharms JRE (2007). The cetacean environment off southern Africa. In Best PB & Folkens PA (eds) The whales and dolphins of the southern African subregion, 5-13. Cambridge: Cambridge University Press.

On the recent warming of the Agulhas Current

[1] Rouault M, Lee-Thorp AM, Ansorge I & Lutjeharms JRE (1995). Agulhas Current Air-Sea Exchange Experiment. South African Journal of Science 91:493-496.

[2] Rouault M, Lee-Thorp AM & Lutjeharms JRE (2000). Observations of the atmospheric boundary layer above the Agulhas Current during along-current winds. Journal of Physical Oceanography 30:70-85.

[3] Lee-Thorp AM, Rouault M & Lutjeharms JRE (1998). Cumulus cloud formation above the Agulhas Current. South African Journal of Science 94:351-354.

[4] Rouault M, White SA, Reason CJC, Lutjeharms JRE & Jobard I (2002). Ocean-atmosphere interaction in the Agulhas Current and a South African extreme weather event. Weather and Forecasting 17, 4:655-669.

[5] Biastoch A, Boning, CW & Lutjeharms JRE (2008). Agulhas leakage dynamics affects decadal variability in Atlantic overturning circulation. Nature 456:489-492.

[6] Vazquez J, Perry K & Kilpatrick K (1998). NOAA/NASA AVHRR Oceans Pathfinder Sea Surface Temperature Data Set User’s Reference Manual Version 4.0, 10 April 1998. JPL Publication D-14070.

[7] Rio M-H & Hernandez F (2004). A mean dynamic topography computed over the world ocean from altimetry, in situ measurements, and a geoid model. Journal of Geophysical Research 109, C12032, DOI:10.1029/2003JC002226.

[8] Rouault M, Penven P & Pohl B (2009). Warming of the Agulhas Current since the 1980s. Geophysical Research Letters 36, L12602, DOI:10.1029/2009GL037987.

Climate change and variability in southern Africa and regional ocean influences

[1] Rouault M & Richard Y (2003). Intensity and spatial extension of drought in South Africa at different time scales. Water SA 29, 4:489-500.

[2] Rouault M & Richard Y (2005). Intensity and spatial extent of droughts in southern Africa. Geophysical Research Letters 32, L15702, DOI:10.1029/2005GL022436.

[3] Richard Y, Trzaska S, Roucou P & Rouault M (2000). Modification of the Southern African rainfall variability/El Niño Southern Oscillation relationship. Climate Dynamics 16:886-895.

[4] Richard Y, Fauchereau N, Poccard I, Rouault M, Trzaska S (2001). 20th Century droughts in southern Africa: spatial and temporal variability, teleconnections with oceanic and atmospheric conditions. International Journal of Climatology 21:873-885.

[5] Saji NH, Goswami BN, Vinayachandran PN & Yamagata T (1999). A dipole mode in the Tropical Indian Ocean. Nature 401:360-363.

[6] Reason CJC (2002). Sensitivity of the southern African circulation to dipole SST patterns in the South Indian Ocean. International Journal of Climatology 22:377-393.

[7] Fauchereau N, Trzaska S, Richard Y, Roucou P & Camberlin P (2003). SST co-variability in the Southern Atlantic and Indian Oceans and its connections with the atmospheric circulation in the Southern Hemisphere. International Journal of Climatology 23, 6:663-677.

[8] Hermes JC & Reason CJC (2005). Ocean model diagnosis of interannual co-evolving SST variability in the South Indian and Atlantic Oceans. Journal of Climate 18:2864-2882.

[9] Rouault M, Florenchie P, Fauchereau N & Reason CJC (2003). South East tropical Atlantic warm events and southern African rainfall. Geophysical Research Letters 30, 5, 8009, DOI:10.1029/2002GL014840.

[10] Rouault M, Illig S, Bartholomae C, Reason CJC & Bentamy A (2007). Propagation and origin of warm anomalies in the Angola Benguela upwelling system in 2001. Journal of Marine Systems 68:477-488.

[11] Boebel O, Lutjeharms JRE, Schmid C, Zenk W, Rossby HT & Barron C (2003). The Cape Cauldron: a regime of turbulent inter-ocean exchange. Deep-Sea Research II 50:57-86.

[12] Singleton AT & Reason CJC (2007). Variability in the characteristics of cut-off low pressure systems over subtropical southern Africa. International Journal of Climatology 27: 295-310.

[13] Reason CJC & Rouault M (2005). Links between the Antarctic Oscillation and winter rainfall over southwestern South Africa. Geophysical Research Letters 32, L07705, DOI:10.1029/2005GL0022419.


[14] Blamey R & Reason CJC (2007). Relationships between Antarctic sea-ice and South African winter rainfall. Climate Research 33:183-193.

[15] Reason CJC & Jagadheesha D (2005). Relationships between South Atlantic SST variability and atmospheric circulation over the South African region during austral winter. Journal of Climate 18:3059-3075.

[16] Reason CJC, Landman W & Tennant W (2006). Seasonal to decadal prediction of southern African climate and its links with variability of the Atlantic Ocean. Bulletin of American Metereological Society 87:941-955.

[17] Reason CJC & Rouault M (2007). Predicting South African rainfall. Quest, Science for South Africa, Academy of Science of South Africa 4, 1:10-11.

The impacts of ocean acidification on a keystone Southern Ocean species

[1] Feely RA, Sabine CL, Lee K, Berelson W, Kleypas J, Fabry VJ & Millero FJ (2004). Impact of anthropogenic CO2 on the CaCO3 system in the oceans. Science 305:362-366.

[2] Sabine CL, Feely RA, Gruber N, Key RM, Lee K, Bullister JL, Wanninkhof R, Wong CS, Wallace DWR, Tilbrook B, Millero FJ, Peng T-H, Kozyr A, Ono T & Rios AF (2004). The oceanic sink for anthropogenic CO2. Science 305:367-371.

[3] Orr JC, Fabry VJ, Aumont O, Bopp L, Doney SC, Feely RA, Gnanadesikan A, Gruber N, Ishida A, Joos F, Key RM, Lindsay K, Maier-Reimer E, Matear R, Monfray P, Mouchet A, Najjar G, Plattner G-K, Rodgers KB, Sabine CL, Sarmiento JL, Schlitzer R, Slater RD, Totterdell IJ, Weirig M-F, Yamanaka Y & Yool A (2005). Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms. Nature 437:681-686.

[4] Caldeira K & Wickett ME (2003). Anthropogenic carbon and ocean pH. Nature 425:365-368.

[5] Kleypas JA, Feely RA, Fabry VJ, Langdon C, Sabine CL & Robbins LL (2006). Impacts of Ocean Acidification on Coral Reefs and Other Marine Calcifiers. A Guide for Future Research. Report of a workshop sponsored by NSF, NOAA and the USGS. St. Petersburg, Florida.

[6] Bernard KS & Froneman PW (2009). The sub-Antarctic euthecosome pteropod, Limacina retroversa: Distribution patterns and trophic role. Deep-Sea Research Part I 56, 4:582-598.

[7] Hunt BPV, Pakhomov EA, Hosie GW, Siegel V, Ward P & Bernard KS (2008). Pteropods on Southern Ocean ecosystems. Progress in Oceanography 78:193-221.

[8] Legendre L & Le Fèvre J (1992). Interactions between hydrodynamics and pelagic ecosystems: relevance to resource exploitation and climate change. South African Journal of Marine Science 12:477-486.

[9] Lalli CM & Gilmer RW (1989). Pelagic snails: The biology of holoplanktonic gastropod mollusks. Stanford, California: Stanford University Press.

[10] Armstrong JL, Boldt JL, Cross AD, Moss JH, Davis ND, Myers KW, Walker RV, Beauchamp DA & Haldorson LJ (2005). Distribution, size, and interannual, seasonal, and diel food habits of northern Gulf of Alaska juvenile pink salmon, Oncorhynchus gorbuscha. Deep-Sea Research II 52:247-265.

[11] Bushula T, Pakhomov EA, Kaehler S, Davis S & Kalin RM (2005). Diet and daily ration of two nototheniid fish on the shelf of the sub-Antarctic Prince Edward Islands. Polar Biology 28:585-593.

[12] Froneman PW & Pakhomov EA (1998). Trophic importance of the chaetognaths Eukrohnia hamata and Sagitta gazellae in the pelagic system of the Prince Edward Islands (Southern Ocean). Polar Biology 19:242-249.

[13] Froneman PW, Pakhomov EA, Perissinotto R & Meaton V (1998). Feeding and predation impact of two chaetognath species, Eukrohnia hamata and Sagitta gazellae, in the vicinity of Marion Island (Southern ocean). Marine Biology 131:95-101.

[14] Pakhomov EA & Perissinotto R (1996). Trophodynamics of the hyperiid amphipod Themisto gaudichaudi in the South Georgia region during late austral summer. Marine Ecology Progress Series 134:91-100.

[15] Pakhomov EA, Perissinotto R & McQuaid CD (1996). Prey composition and daily rations of myctophid fishes in the Southern Ocean. Marine Ecology Progress Series 134:1-14.

[16] Perissinotto R & McQuaid CD. (1992). Land-based predator impact on vertically migrating zooplankton and micronekton advected to a Southern Ocean archipelago. Marine Ecology Progress Series 80:15-27.

[17] Accornero A, Manno C, Esposito F & Gambi MC (2003). The vertical flux of particulate matter in the polynya of Terra Nova Bay. Part II. Biological components. Antarctic Science 15:175-188.

[18] Noji TT, Bathmann UV, Von Bodungen B, Voss M, Antia A, Krumbholz M, Klein B, Peeken I, Noji C-IM & Rey F (1997). Clearance of picoplankton-sized particles and formation of rapidly sinking aggregates by the pteropod, Limacina reiroversa. Journal of Plankton Research 19:863-875.

[19] Yoon WD, Kim SK & Han KN (2001). Morphology and sinking velocities of fecal pellets of copepod, molluscan, euphausiid, and salp taxa in the northeastern tropical Atlantic. Marine Biology 139:923-928.

[20] Bathmann UV, Noji TT & Von Bondungen B (1991). Sedimentation of pteropods in the Norwegian Sea in autumn. Deep-Sea Research A 38:1341-1360.

[21] Gilmer RW & Harbison GR (1986). Morphology and field behavior of pteropod molluscs: feeding methods in the families Cavoliniidae, Limacinidae and Peraclididae (Gastropoda: Thecosomata). Marine Biology 91:47-57.

[22] Berner RA & Honjo S (1981). Pelagic sedimentation of aragonite: its geochemical significance. Science 211:940-942.

SAECON’s approach to long-term environmental observation

[1] UN (2002). Johannesburg Declaration on Sustainable Development [online]. Available from: http://www.undocuments. net/jburgdec.htm.

[2] SAEON Advisory Board (2003). Design of the South African Environmental Observation Network (SAEON). (Unpublished Report). Pretoria: SAEON.

[3] Millenium Ecosystem Assessment (2005). Ecosystems and Human Well-being: Current State & Trends Assessment. Washington DC: Island Press.

[4] O’Connor TG (2010). Understanding the environmental change in complex systems: SAEON core science framework. Pretoria: SAEON.

[5] GTOS (2010). Global Terrestrial Observing System [online]. Available from: http://www.fao.org/gtos/.

[6] GOOS (2010). Global Ocean Observing System [online]. Available from: http://www.ioc-goos.org.

[7] Bender EA, Case TJ & Gilpin ME (1984). Perturbation experiments in community ecology: theory and practice. Ecology 65:1-13.

CONTRIBUTING AUTHORS 299

Contributing Authors

299

Annandale, John G.Department of Plant Production and Soil Science, University of Pretoria, Pretoria 0002, South Africa, E-mail: [email protected], Tel.: 012 420 3223, Fax.: 012 420 4120.

Archer, Emma R.M.Climate Change, Council for Scientific and Industrial Research (CSIR): Natural Resources and the Environment, Pretoria 0002, South Africa, E-mail: [email protected], Tel.: 012 841 4439, Fax.: 012 841 2597.

Archibald, SallyEcosystems Processes and Dynamics, Council for Scientific and Industrial Research (CSIR): Natural Resources and the Environment, Pretoria 0002, South Africa, E-mail: [email protected], Tel.: 012 841 3487, Fax.: 012 841 2689.

Asner, Gregory P.Carnegie Institution for Science, Department of Global Ecology, 260 Panama Street, Stanford, CA, 94305, USA, E-mail: [email protected], Tel.: +1-650-462-1047.

Beletse, Yacob G.Department of Plant Production and Soil Science, University of Pretoria, Pretoria 0002, South Africa, E-mail: [email protected], Tel.: 012 841 9890, Fax.: 012 808 0844.

Bernard, Kim S.Elwandle Node, South African Environmental Observation Network, Private Bag X1015, Grahamstown 6139, South Africa, E-mail: [email protected], Tel.: 046 622 9899, Fax.: 046 622 9899.

Bristow, Keith L.CSIRO Land and Water / CRC Irrigation Futures, PMB Aitkenvale, Townsville, QLD 4814, Australia, E-mail: [email protected], Tel.: +61 7 4753 8596, Fax.: +61 7 4753 8600.

Brundrit, GeoffGlobal Ocean Observing System in Africa, P.O. Box 260, Simon’s Town 7995, South Africa, E-mail: [email protected], Tel.: 021 786 2308, Fax. : 021 786 5369.

Bundy, Simon C.Sustainable Development Projects CC, P.O. Box 1016, Ballito 4420, South Africa, E-mail: [email protected], Tel.: 032 946 0685, Fax.: 032 946 0686.

Cartwright, Anton117 Hatfield Street, Gardens, Cape Town 8001, South Africa, E-mail: [email protected], Tel.& Fax.: 021 465 6905.

Cho, MosesEcosystems Earth Observation & Meraka: Remote Sensing Research Unit, Meraka Institute, Council for Scientific and Industrial Research (CSIR): Natural Resources and the Environment, Pretoria 0002, South Africa, E-mail: [email protected], Tel.: 012 841 2790.

Chown, Steven L.DST-NRF Centre of Excellence for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa, E-mail: [email protected], Tel.: 021 808 2385, Fax.: 021 808 2995.


Cockcroft, Andrew C.Fisheries, Department of Agriculture, Forestry and Fisheries, Private Bag X2, Rogge Bay 8012, Cape Town, South Africa, E-mail: [email protected], Tel.: 021 402 3132, Fax.: 021 402 3034.

Coetzee, Janet C.Fisheries, Department of Agriculture, Forestry and Fisheries, Private Bag X2, Rogge Bay 8012, Cape Town, South Africa, E-mail: [email protected], Tel.: 021 402 3176, Fax.: 021 402 3639.

Coetzer, Kaera L.School of Animal Plant and Environmental Science, University of the Witwatersrand, Private Bag X3, Wits 2050, Johannesburg, South Africa, E-mail: [email protected], Cell: 083 479 5420, Fax.: 011 403 1429.

Coetzer, WillemSouth African Institute for Aquatic Biodiversity, Private Bag X1015, Grahamstown 6140, South Africa, E-mail: [email protected], Tel.: 046 603 5800, Fax.: 046 622 2403.

Coppin, PolKatholieke Universiteit Leuven, Biosystems, M3-BIORES, Willem de Croylaan 34, B-3001, Leuven, Belgium, E-mail: [email protected], Tel.: +32 +16 329749.

Cowley, Paul D.South African Institute for Aquatic Biodiversity, Private Bag X1015, Grahamstown 6140, South Africa, E-mail: [email protected], Tel.: 046 603 5805, Fax.: 046 622 2403.

Crawford, Robert J.M.Marine and Coastal Management, Department of Water Affairs, Private Bag X2, Rogge Bay 8012, Cape Town, South Africa, E-mail: [email protected], Tel.: 021 402 3140, Fax.: 021 402 3330.

Dean, W. Richard J.Percy FitzPatrick Institute for African Ornithology, University of Cape Town, Rondebosch 7700, South Africa, E-mail: [email protected], Tel.: 023 541 1828.

Dekker, GeoffGeomatics Services, City of Cape Town, 121 Loop Street, Cape Town 8001, South Africa, E-mail: [email protected], Tel.: 021 487 2327.

Dwyer, Patrick C.Remote Sensing Research Unit, Meraka Institute, Council for Scientific and Industrial Research (CSIR): Natural Resources and the Environment, P.O. Box 395, Pretoria 0001, South Africa, E-mail: [email protected], Tel.: 012 841 3100, Fax.: 012 841 3124.

Erasmus, Barend F.N.School of Animal Plant and Environmental Science, University of the Witwatersrand, Private Bag X3, Wits 2050, Johannesburg, South Africa, E-mail: [email protected], Tel.: 011 717 6449, Fax.: 011 403 1429.

Fairhurst, LucindaLaquaR Consultants CC, P.O. Box 474, Eppindust 7475, Cape Town, South Africa, E-mail: [email protected], Cell: 073 511 1717.

Fisher, Jolene T.School of Animal Plant and Environmental Science, University of the Witwatersrand, Private Bag X3, Wits 2050, Johannesburg, South Africa, E-mail: [email protected], Cell: 072 338 0882, Fax.: 011 403 1429.

Goschen, Wayne S.Egagasini Node, South African Environmental Observation Network, Private Bag X2, Rogge Bay 8012, Cape Town, South Africa, E-mail: [email protected], Tel.: 021 402 3547.

Götz, AlbrechtElwandle Node, South African Environmental Observation Network, 18 Somerset Street, Grahamstown 6140, South Africa, E-mail: [email protected], Tel./Fax.: 046 622 9899.

Griffiths, Charles L.Marine Biology Research Centre and Centre for Invasion Biology, Zoology Department, University of Cape Town, Rondebosch 7700, South Africa, E-mail: [email protected], Tel.: 021 650 3610, Fax.: 021 650 4988.

Guastella, Lisa A-M.AS Consulting CC, 29 Brown’s Grove, Sherwood, Durban 4091, South Africa; Department of Oceanography, University of Cape Town, Rondebosch 7700, South Africa, E-mail: [email protected], Tel.: 031 208 6896, Fax.: 086 602 4642.

Guldemond, Robert A.R.Conservation Ecology Research Unit, University of Pretoria, Pretoria 0002, South Africa, E-mail: [email protected], Tel.: 012 420 3231, Fax.: 012 420 4523.

Hermes, Juliet C.Egagasini Node, South African Environmental Observation Network, Private Bag X2, Rogge Bay 8012, Cape Town, South Africa, E-mail: [email protected], Tel.: 021 402 3547, Fax.: 021 402 3674.

Hoffman, M. TimmPlant Conservation Unit, Botany Department, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa, E-mail: [email protected], Tel.: 021 650 2440.

Huntley, Brian J.South African National Biodiversity Institute, Kirstenbosch, Private Bag X7, Claremont 7755, Cape Town, South Africa, E-mail: [email protected], Tel./Fax.: 028 272 9138.

Hutchings, Laurence F.Ecosystem Utilization and Conservation, Department of Environmental Affairs, Private Bag X2, Rogge Bay 8012, Cape Town, South Africa; Marine Research Institute, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa, E-mail: [email protected], Tel.: 021 402 3109, Fax.: 021 402 3639.

Impson, N. DeanCape Nature: Scientific Services, Private Bag X29, Rondebosch 7701, Cape Town, South Africa, E-mail: [email protected], Tel.: 021 866 8018, Fax.: 021 866 1523.

Iponga, Donald M.DST-NRF Centre of Excellence for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa, E-mail: [email protected], Tel.: 021 808 3403, Cell: 072 490 4906, Fax.: 021 808 2995.

James, Nicola C.South African Institute for Aquatic Biodiversity, Private Bag X1015, Grahamstown 6140, South Africa, E-mail: [email protected], Tel.: 046 603 5839, Fax.: 046 622 2403.

Kok, Pieter C.Migration Consultant, P.O. Box 12693, Clubview, Centurion 0014, South Africa, E-mail: [email protected], Cell: 082 338 0783, Fax.: 086 617 9234.

Kotze, IanAgricultural Research Council, Institute for Soil, Climate and Water, Private Bag X5017, Stellenbosch 7599, South Africa, E-mail: [email protected], Tel.: 021 887 4690.

Laakso, LauriDivision of Atmospheric Sciences, Department of Physical Sciences, University of Helsinki; School of Physical and Chemical Sciences, North-West University, Private Bag X6001, Potchefstroom 2520, South Africa, E-mail: [email protected], Cell: 082 342 7830, Tel.: 018 299 1068.

Le Maitre, DavidCouncil for Scientific and Industrial Research (CSIR): Natural Resources and the Environment, P.O. Box 320, Stellenbosch 7599, South Africa, E-mail: [email protected], Tel.: 021 888 2407/2460, Cell: 072 337 0657, Fax.: 021 888 2684.

Le Roux, Peter C.DST-NRF Centre of Excellence for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa, E-mail: [email protected], Tel.: 021 808 2832, Fax.: 021 808 2995.

Lukey, PeterDepartment of Environmental Affairs and Tourism, Private Bag X447, Pretoria 0001, South Africa, E-mail: [email protected], Tel.: 012 310 370, Fax.: 012 322 2476.

Lutjeharms, Johann R.E.Department of Oceanography, University of Cape Town, Rondebosch 7700, South Africa, E-mail: [email protected], Tel.: 021 650 3279, Fax.: 021 650 3979.

Main, RusselEcosystems Earth Observation, Council for Scientific and Industrial Research (CSIR): Natural Resources and the Environment, Pretoria 0002, South Africa, E-mail: [email protected], Tel.: 012 841 2790.

CONTRIBUTING AUTHORS 301

Pienaar, Jakobus J.Faculty of Natural Science, North-West University, Potchefstroom Campus, Private Bag X6001, Potchefstroom 2520, South Africa, E-mail: [email protected], Tel.: 018 299 2301, Fax.: 018 299 2447.

Piketh, Stuart J.Climatology Research Group, University of the Witwatersrand, Private Bag X3, Wits 2050, Johannesburg, South Africa, E-mail: [email protected], Tel.: 011 717 6532, Fax.: 011 717 6535.

Pillay, Dechlan L.Remote Sensing Research Unit, Meraka Institute, Council for Scientific and Industrial Research (CSIR): Natural Resources and the Environment, Pretoria 0002, South Africa, E-mail: [email protected], [email protected], Cell: 083 564 2556.

Pauw, JohanSouth African Environmental Observation Network, 211 Skinner Street, P.O. Box 1758, Pretoria 0001, South Africa, E-mail: [email protected], Tel.: 012 392 9371, Fax.: 012 392 9316.

Pohl, BenjaminCentre de Recherches de Climatologie, Universite de Bourgogne, CNRS, Dijon, France, E-mail: [email protected].

Pretorius, J.P.Federation for a Sustainable Environment, P.O. Box 201, Belfast 1100, South Africa, E-mail: [email protected], Cell: 083 986 4400.

Ramaswiela, TshililoDST-NRF Centre of Excellence for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa, E-mail: [email protected], Tel.: 021 808 2832, Fax.: 021 808 2995.

Reason, Chris J.C.Department of Oceanography, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa, E-mail: [email protected], Tel.: 021 650 5311, Fax.: 021 650 3979.

Richardson, David M.DST-NRF Centre of Excellence for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa, E-mail: [email protected], Tel.: 021 808 3711, Cell: 082 762 4201, Fax.: 021 808 2995.

Richardson, F. DavidDepartment of Mathematics and Applied Mathematics, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa, E-mail: [email protected], Tel.: 021 850 2112.

Rohde, RickCentre for African Studies, University of Edinburgh, c/o 4 Carlton Street, Edinburgh, EH4 1 NJ, United Kingdom, E-mail: [email protected], Tel.: +44 131 332 4147.

Rouault, MathieuDepartment of Oceanography, Marine Research Institute, University of Cape Town, Rondebosch 7700, South Africa, E-mail: [email protected].

Ryan, Peter G.Percy FitzPatrick Institute of African Ornithology, University of Cape Town, Rondebosch 7700, South Africa, E-mail: [email protected], Tel.: 021 650 2966, Fax.: 021 650 3295.

Scott, DaveFRBC Research Chair, Earth & Environmental Sciences, Watershed Management, Barber Arts & Sciences Unit 3, UBC Okanagan, Kelowna, B.C., Canada, E-mail: [email protected], Tel.: +250 807 8755, Fax.: +250 807 8005.

Sekwele, Ramogale C.Department of Water Affairs, Directorate: Resource Quality Services, Private Bag X313, Pretoria 0001, South Africa, E-mail: [email protected], Tel.: 012 808 9614, Fax.: 012 809 0338.

Shaw, Justine D.DST-NRF Centre of Excellence for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa, E-mail: [email protected], Tel.: 021 808 2832, Fax.: 021 808 2995.

Malherbe, JohanAgrometeorology Division, ARC-Institute for Soil, Climate and Water, Private Bag X79, Pretoria 0001, South Africa, E-mail: [email protected], Tel.: 012 310 2577, Fax.: 012 323 1157.

Mambo, JuliaSchool of Geography, Archaeology and Environmental Studies, University of the Witwatersrand, Private Bag X3, Wits 2050, Johannesburg, South Africa, E-mail: [email protected].

Mather, Andrew A.Coastal and Catchment Policy, Co-ordination and Management, eThekwini Municipality, P.O. Box 680, Durban, 4000, South Africa, E-mail: [email protected], Tel.: 031 311 7281, Fax : 031 305 6952.

Mathieu, RenaudEcosystems Earth Observation & Meraka: Remote Sensing Research Unit, Meraka Institute, Council for Scientific and Industrial Research (CSIR): Natural Resources and the Environment, Pretoria 0002, South Africa, E-mail: [email protected], Tel.: 012 841 2790.

Matlala, MolokoWater Resources Information Programmes, Department of Water Affairs, Private Bag X313, Pretoria 0001, South Africa, E-mail: [email protected], Tel.: 012 336 7860, Cell: 082 802 3052, Fax.: 012 336 6935.

McCarthy, Terence S.School of Geosciences, University of the Witwatersrand, P.O. Box X3, Wits 2050, Johannesburg, South Africa, E-mail: [email protected], Tel.: 011 717 6547, Fax.: 011 717 6579.

McGeoch, Melodie A.Cape Research Centre, South African National Parks, P.O. Box 216, Steenberg 7947, South Africa, E-mail: [email protected], Tel.: 021 712 0131, Fax.: 021 713 7509.

Mead, AngelaMarine Biology Research Centre and Centre for Invasion Biology, Zoology Department, University of Cape Town, Rondebosch 7700, South Africa, E-mail: [email protected], Tel.: 021 650 3610, Fax.: 021 650 4988.

Meiklejohn, K. IanDepartment of Geography, Rhodes University, P.O. Box 94, Grahamstown 6140, South Africa, E-mail: [email protected], Tel.: 046 603 8024, Cell: 083 342 1255, Fax.: 046 636 1199.

Midgley, Guy F.Climate Change and BioAdaptation, Kirstenbosch Research Center, South African National Biodiversity Institute, Private Bag X7, Claremont 7735, South Africa, E-mail: [email protected], Tel.: 021 799 8707, Cell: 082 569 2810, Fax.: 021 797 6903.

Milton, Suzanne J.Percy FitzPatrick Institute for African Ornithology, University of Cape Town, Rondebosch 7700, South Africa, E-mail: [email protected], Tel.: 023 541 1828.

Newby, Terence S.Earth Observation Division, ARC-Institute for Soil, Climate and Water, Private Bag X79, Pretoria 0001, South Africa, E-mail: [email protected], Tel.: 012 310 2587, Fax.: 012 323 1157.

Norris-Rogers, MarkMondi SA, Forest Division, P.O. Box 39, Pietermaritzburg 3200, KwaZulu-Natal, South Africa, E-mail: [email protected], Tel.: 033 897 4029.

O’Connor, Tim G.South African Environmental Observation Network, 211 Skinner Street, P.O. Box 1758, Pretoria 0001, South Africa, E-mail: [email protected], Tel.: 033 343 3491.

Oelofse, GreggStrategic Planning, City of Cape Town, 44 Wale Street, Cape Town 8001, South Africa, E-mail: [email protected], Tel.: 021 487 2239, Fax.: 021 487 2578.

Paterson, Angus W.South African Environmental Observation Network, Elwandle Node, Private Bag X1015, Grahamstown 6140, South Africa, E-mail: [email protected], Tel./Fax.: 046 622 9899.

Penven, PierrickLaboratoire de Physique des Oceans, Ifremer, BP 70, F-29280 Plouzane, France, E-mail: [email protected].


Skelton, Paul H.South African Institute for Aquatic Biodiversity, Private Bag X1015, Grahamstown 6140, South Africa, E-mail: [email protected], Tel.: 046 603 5800, Cell: 082 903 1615, Fax.: 046 622 2403.

Smit, Izak P.J.South African National Parks, Scientific Services, Skukuza, South Africa, E-mail: [email protected], Tel.: 013 735 4257.

Smith, Alan M.AS Consulting CC, 29 Brown’s Grove, Sherwood, Durban 4091, South Africa; School of Geological Sciences, University of KwaZulu-Natal, Durban 4001, South Africa, E-mail: [email protected], Tel.: 031 208 6896, Fax.: 086 602 4642.

Somers, BenKatholieke Universiteit Leuven, Biosystems, M3-BIORES, Willem de Croylaan 34, B-3001, Leuven, Belgium, E-mail: [email protected], Tel.: +32 16 329749.

Steenkamp, KarenRemote Sensing Research Unit, Meraka Institute, Council for Scientific and Industrial Research (CSIR): Natural Resources and the Environment, P.O. Box 395, Pretoria 0001, South Africa, E-mail: [email protected], Tel.: 012 841 3100, Fax.: 012 841 3124.

Stirzaker, Richard J.CSIRO Land and Water / CRC Irrigation Futures, P.O. Pox 1600, Canberra, ACT 2601, Australia, E-mail: [email protected], Tel.: +61 2 6246 5570, Fax.: +61 2 6246 5800.

Terauds, AleksDST-NRF Centre of Excellence for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa, E-mail: [email protected], Tel.: 021 808 2832, Fax.: 021 808 2995.

Theron, André K.Coast & Ocean Competency Area, Council for Scientific and Industrial Research (CSIR): Natural Resources and the Environment, P.O. Box 320, Stellenbosch 7599, South Africa, E-mail: [email protected], Tel.: 021 888 2511, Fax.: 021 888 2693.

Twine, WayneSchool of Animal Plant and Environmental Sciences, University of the Witwatersrand, Wits Rural Facility, Private Bag X420, Acornhoek 1360, South Africa, E-mail: [email protected]; [email protected], Tel.: 015 793 7500, Fax.: 015 793 7500.

Van Aarde, Rudi J.Conservation Ecology Research Unit, University of Pretoria, Pretoria 0002, South Africa, E-mail: [email protected], Tel.: 012 420 2753, Fax.: 012 420 4523.

Van Aardt, Jan A.N.Rochester Institute of Technology, Center for Imaging Science, 54 Lomb Memorial drive, Rochester, NY, 14623, USA, E-mail: [email protected], Tel.: +1 585 475 4229.

Van Jaarsveld, Albert S.Research and Innovation Support and Advancement, National Research Foundation, P.O. Box 2600, Pretoria, 0001, South Africa, E-mail: [email protected], Tel.: 012 481 4137, Fax.: 012 481 4006.

Van der Lingen, Carl D.Fisheries, Department of Agriculture, Forestry and Fisheries, Private Bag X2, Rogge Bay 8012, Cape Town, South Africa; Marine Research Institute, University of Cape Town, Rondebosch 7700, South Africa, E-mail: [email protected], Tel.: 021 402 3168, Fax.: 021 402 3639.

Van Tonder, J. LouisDemographic Analysis, Statistics South Africa, Private Bag X44, Pretoria 0001, South Africa, E-mail: [email protected], Tel.: 012 310 2152, Cell: 082 888 2589, Fax.: 012 310 8339.

Van Wilgen, Brian W.Centre for Invasion Biology, Council for Scientific and Industrial Research (CSIR): Natural Resources and the Environment, P.O. Box 320, Stellenbosch, 7599, South Africa, E-mail: [email protected], Tel.: 021 888 2400, Fax.: 021 888 2693.

Van Wilgen, Nicola J.DST-NRF Centre of Excellence for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa, E-mail: [email protected], Tel.: 021 808 2832, Cell: 072 118 1478, Fax.: 021 808 2995.

Van Zyl, DawieEarth Observation Division, ARC-Institute for Soil, Climate and Water, Private Bag X79, Pretoria 0001, South Africa, E-mail: [email protected], Tel.: 012 310 2679, Fax.: 012 323 1157.

Verreynne, StephanCitrus Research International, Department of Horticultural Science, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa, E-mail: [email protected], Tel.: 021 808 2825.

Versfeld, DirkWater Resources and Forestry Consultant, 42 Jordaan Street, Cape Town 8001, E-mail: [email protected], Cell: 082 377 4084, Fax.: 021 424 1787.

Verstraeten, WillemKatholieke Universiteit Leuven, Biosystems, M3-BIORES, Willem de Croylaan 34, B-3001, Leuven, Belgium, E-mail: [email protected], Tel.: +32 16 329749.

Vogel, ColeenREVAMP Research Group, School of Geography, Archaeology and Environmental Studies, University of the Witwatersrand, Private Bag X3, Wits 2050, Johannesburg, South Africa, E-mail: [email protected], Tel.: 011 717 6510.

Von Maltitz, GrahamEcosystems Processes and Dynamics, Council for Scientific and Industrial Research (CSIR): Natural Resources and Environment, Pretoria 0002, South Africa, E-mail: [email protected], Tel.: 012 841 3640, Fax.: 012 841 2689.

Ward, DavidSchool of Biological and Conservation Sciences, University of KwaZulu-Natal, Scottsville 3209, South Africa, E-mail: [email protected], Tel.: 033 260 6018, Fax.: 033 260 5105.

Wassenaar, Theo D.Conservation Ecology Research Unit, University of Pretoria, Pretoria 0002, South Africa; African Wilderness Restoration, P.O. Box 11997, Klein Windhoek, Namibia, E-mail: [email protected], Tel./Fax.: +264 61 230345.

Wessels, Konrad J.Ecosystems Earth Observation & Meraka: Remote Sensing Research Unit, Meraka Institute, Council for Scientific and Industrial Research (CSIR): Natural Resources and the Environment, P.O. Box 395, Pretoria 0001, South Africa, E-mail: [email protected], Tel.: 012 841 3100, Fax.: 012 841 3124.

Whitfield, Alan K.South African Institute for Aquatic Biodiversity, Private Bag X1015, Grahamstown 6140, South Africa, E-mail: [email protected], Tel.: 046 603 5829, Fax.: 046 622 2403.

Zietsman, Hendrik L. (Larry)Geographical Systems Research Bureau, Stellenbosch 7600, South Africa, E-mail: [email protected], Cell: 079 880 0236, Fax.: 021 887 1433.

9Q��8F�9Q(;�;F�#(�� 303303

Photographic credits which do not appear with the respective photographs are listed below.

��-� ��'��"��F��

��+� ��/��

��7� F�� 9��Q��

��7�� ;��/��"��

��5� 8��9��Q��

��-+7� (��F��

��-45� (�� >�� )�� 9��Q��

��-5,� (��"��9��Q��

��-5+� ��9��Q��

��+-,� ��9��Q��

��+++� ;��)��"�� "��>�� =��)?�8��

��+4�� "��/��

��+5+�� 9��Q��

��+33�� '��"��F��

��6,6� Q�"��/��

��6,7� ��"��"��;��%��=��O��

Photographic Credits

Environmental changes are progressively affecting the future of South Africans through their combined impacts on human livelihood, security and prosperity.

This book is about environmental change in South Africa, its causes, trends, implications, suggested solutions and the technologies and methodologies of observation and analysis. It draws together work from as many scientific disciplines as possible to inform not only the private sector and political decision makers, but also the general public on current environmental issues and challenges.

Observations on Environmental Change in South Africa provides pertinent scientific evidence to assist the people of our country in formulating intelligent and responsible policies and practices for the betterment of our society and to ensure the long-term sustainable futures of South Africans.

saeon proef 5 - front-part 3 · the mandate of the south african environmental observation network...

Documents