utspeaks: keeping seas green
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Can preserving humble seagrass help protect us from the extremes of human-induced climate change? The oceans have long been recognised by science as vital for capturing carbon and renewing the atmospheric balance that preserves life on earth. While vast amounts carbon are captured by phytoplankton, less well known has been the role played by seagrasses in storing carbon, cleansing the air and providing essential habitat for marine life. Based on latest UTS marine research, this public lecture reveals the essential place of seagrasses in global ecology, the growing threats to its continued viability and the work that is being done to rehabilitate the areas of seagrass habitat already lost. Professor Bill Gladstone Marine biologist Bill Gladstone applies scientific understanding to solve problems in marine conservation and environmental management. His interests lie in assessing conservation values in marine ecosystems, the selection and management of marine parks, and community participation in marine conservation. He has worked throughout NSW, the Great Barrier Reef, Torres Strait, the Coral Triangle, and the Middle East. Dr Peter Macreadie Marine ecologist Peter Macreadie is a UTS Chancellor’s Postdoctoral Research Fellow. His research cover a wide range of systems; from deep-sea reefs to intertidal oyster reefs. Peter’s current research focuses on seagrasses to better understand how their resilience to climate change can be improved, and how can we capitalise on their ability to capture and store atmospheric carbon. Professor Peter Ralph Peter Ralph has been working with seagrasses since the early 90’s, when he pioneered the use of optical methods of measuring photosynthesis to examine the impact of pollution on seagrass health. More recently, he is developing new tools to assess the ability of an entire seagrass meadow to fix carbon. This work is now part of an international research agenda lead by the International Union for Conservation of Nature (IUCN) to demonstrate the importance of seagrasses in the global carbon cycle. UTSpeaks is an annual free public lecture series presented by UTS experts discussing a range of important issues confronting contemporary Australia. Use the hashtag #utspeaks to tweet about the lecture on Twitter.TRANSCRIPT
UTSpeaks: Keeping seas green17 November, 2011UTSpeaks: Keeping seas green17 November, 2011
CAN PRESERVING HUMBLE SEAGRASS HELP PROTECT US FROM THE EXTREMES OF HUMAN-INDUCED CLIMATE CHANGE?
● Bill Gladstone– Values and services– Loss and recovery
● Peter Macreadie– Seagrass as a carbon sink– Carbon capture and storage
● Peter Ralph– Protecting seagrass carbon
What are we talking about?What are we talking about?
SeagrassesSeagrasses
● Marine flowering plants
● Australia: a global hotspot– Greatest number of
seagrass species (50%)– Largest area (95,000 km2)
Mcleod et al 2011
Where is it, how much is there, how is it changing?Where is it, how much is there, how is it changing?
● Global seagrass area 177,000 - 600,000 km2
● Mapping seagrass:– diver surveys– side scan sonar– aerial imagery– satellite remote sensing
● Uncertainties in estimates of seagrass area and rate of change:
– technological constraints– lack of historical data – environmental constraints– human capacity constraints
NSW DPI 2008
Values and Services: BiodiversityValues and Services: Biodiversity
● Structural complexity of seagrass– epiphytes– periphytes– encrusting invertebrates– infauna– mobile fauna– fishes, rays, invertebrates– birds
● Charismatic fauna– dugong, turtles, seahorses
● ~ 60 threatened and endangered species rely on seagrass
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Values and Services: Fish Nurseries Values and Services: Fish Nurseries
● 50% of the world's fisheries rely on seagrass
● Seagrass-associated prawn fisheries in North Qld: $1500 ha-1 yr-1
● Seagrass-supported fisheries in South Australia: $100 million yr-1
● Economic and social value of artisanal seagrass-based fisheries
Un
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Values and ServicesValues and Services
Blue Carbon
Coastal Water Quality
Fish NurseriesMarine Biodiversity
Coastline and Beach Stabilisation
Source: Forest Trend
• Climate Change Adaptation
• Sustaining Community Resilience and Coastal Livelihoods
Value, Appreciation, UnderstandingValue, Appreciation, Understanding
Orth et al. 2006
Scientists’ Concerns for SeagrassScientists’ Concerns for Seagrass
Loss of SeagrassLoss of Seagrass
● Global losses– 29% of known area– 7% per year
Location % Seagrass area lost
Clarence River 60%
Lake Macquarie 44%
Tuggerah Lakes 50%
Port Hacking 60%
Botany Bay 58%
NSW 50% CSIRO
Human Activities Damaging SeagrassesHuman Activities Damaging Seagrasses
● More than 1 billion people live within 50 km of seagrass
● In situ impacts– dredging, scouring– changes in water flow– trawling– smothering, shading– contamination
● Indirect impacts– eutrophication – sedimentation– increasing water temperature– introduced species
Seagrasswatch
Consequences of Seagrass LossConsequences of Seagrass Loss
● 70% decline in seagrass cover 40% decline in commercial fish catches– Western Port Bay (Vic)
● 22% decline in seagrass cover 30% decline in commercial and recreational fish catches– Adelaide P
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.gov
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Recovery of SeagrassRecovery of Seagrass
● Vegetative growth● Germination from seed bank● Seed dispersal● Rafting
● Halophila: months● Zostera: years● Posidonia: decades
● Success of seagrass restoration, transplants: 30%– Cost $8,000 to $1 m per hectare
Cos
mos
NSW DPI
Recovering Seagrass: Manly CoveRecovering Seagrass: Manly Cove
Recovering Seagrass: Manly CoveRecovering Seagrass: Manly Cove
Bring Back the Fish
Recovering Seagrass: Shoal BayRecovering Seagrass: Shoal Bay
R Carraro
Recovering Seagrass: Shoal BayRecovering Seagrass: Shoal Bay
18 months
Recovery begins with colonisation by Halophila
Recovering Seagrass: Manly CoveRecovering Seagrass: Manly Cove
Eco Divers
18 months
Local environmental factors and condition of seagrass meadow might compromise recovery potential
Values, Impacts, ConservationValues, Impacts, Conservation
● Seagrasses provide human society with valuable goods and services
● Despite the impacts of their loss, seagrasses continue to decline and natural recovery processes are slow
● The potential for carbon biosequestration by seagrasses (Blue Carbon) provides further support for their conservation
Climate change lingoClimate change lingo
Kosland Science Museum
● Carbon dioxide (CO2) is most significant human-produced greenhouse gas
● Greenhouse effect = global warming ≈ climate change
US Dept of Energy report (Nov 2011):
● “Biggest jump ever in global warming gases”
● CO2 output in 2010 was 6% higher (512 million tonnes) than in 2009
● Greenhouse gas emissions were higher than the worst-case scenario outlined by climate experts (the IPCC)
Climate Change: How are we doing?Climate Change: How are we doing?
Fighting climate change using natureFighting climate change using nature
● Reducing greenhouse gas emissions is necessary, but how do we get rid of all the emissions already floating around the atmosphere?
● Biosequestration: nature’s way of capturing and storing carbon in sediments
● It’s the same process that created fossil fuels in the first place!
istockphoto
Carbon FarmingCarbon Farming
1. Reducing greenhouse gas emissions
2. Capturing and storing carbon in vegetation and soils (creating ‘carbon sinks’)
Terrestrial only. Not aquatic.
RDAMR
Could seagrasses be the most powerful carbon sinks on the planet?Could seagrasses be the most powerful carbon sinks on the planet?
Global area: Tropical Rainforests vs. SeagrassesGlobal area: Tropical Rainforests vs. Seagrasses
Tropical rainforests
Seagrasses
OR
2.5 times the area of
Australia
The area of VIC or NSW
(?)
Destination 360
IndexOZ
Carbon burial: Tropical Rainforests vs. SeagrassesCarbon burial: Tropical Rainforests vs. Seagrasses
C m-2 y-1
Tg C yr-1
● Terrestrial forests typically store carbon for decades, whereas seagrasses store carbon for millennia!
● Carbon rich deposits can be >10-m thick
● Unlike terrestrial soils, the sediment in seagrass meadows do not become saturated with carbon
● Why? Because the sediments accrete vertically in response to rising sea levels.
Seagrasses are long-term sinksSeagrasses are long-term sinks
‘Leakage’ is a big concern
● Increasing forest productivity can trigger CO2 release from soils
● Increasing CO2 levels in terrestrial soils can stimulate production of other greenhouse gases
Carbon farming: too good to be true?Carbon farming: too good to be true?
iStockPhoto
Do seagrass meadows leak carbon?Do seagrass meadows leak carbon?
Could 1000s of years of ancient carbon leak out into the atmosphere if seagrass meadows are disturbed?
Likely mechanism: loss of seagrass meadows (i.e. the ‘top layer’) exposes buried carbon to the forces of nature
Source
When sinks become sources…When sinks become sources…
Sink
Unhealthy meadows can turn from being carbon sinks, to carbon sources
OpenLight
Negative O2 flux
Carbon sourceCarbon source
Positive O2 flux
Carbon sinkCarbon sink
Measuring FLUX of carbon and oxygenMeasuring FLUX of carbon and oxygen
O2
flux
Night Day Night
Light
level
Ponlachart Chotikarn
Andrew Hume
How do we study carbon capture and storage?How do we study carbon capture and storage?
What impact have humans had on coastal carbon sinks?What impact have humans had on coastal carbon sinks?
Industrial developments:• Tanneries• Sewerage farms• Breweries• Quarries• Oil refineries• Sand mining• Port construction
Consequences:• Loss of seagrass, mangroves, and
saltmarsh• Increases in algae
Proni
Algernon Talmadge R.A.
Paleoreconstruction: going back in timePaleoreconstruction: going back in time
Industrialization weakens coastal carbon sinkIndustrialization weakens coastal carbon sink
Fingerprinting of stored carbon (‘carbon stock’)
CoreMedia
Take home messages so farTake home messages so far
● Highly efficient carbon biosequestration
● Large carbon storage in seagrass sediment
● Carbon stays in the sediment for a long time
● Degradation results in substantial carbon emissions and loss of biosequestration
How to protect seagrass carbon?How to protect seagrass carbon?
● What is Blue Carbon?
● What don't we know?– Can a degraded meadow release it stored carbon?
● How do currently protect plant-based carbon?– How can we protect seagrass carbon?
● What is happening internationally?
● What can you do locally?
Is there carbon leakage ????Is there carbon leakage ????
Assume it “comes out quicker than it goes in”
Assume the loss of seagrass leads to substantial CO2 emissions and loss of highly efficient biosequestrationSacramento Delta example
Drained marshes emit CO2Drained marshes emit CO2
● Sacramento Delta – 1,800 km2 of wetlands (not seagrass)
● has released 1 GtCO2 (1,000,000,000 tons of CO2)
• 50% of tree biomass in Californian forests• 1.5% of California total GHG emissions
● C sequestered over 5,000 years, released in 100 years
wikipedia
Do degraded seagrasses emit CO2?Do degraded seagrasses emit CO2?
● Yes
● Does it contribute to the atmospheric CO2?
– we don’t know,
– If they do, then seagrasses matter, because their loss will further enhance climate change.
How to protect seagrass carbon?How to protect seagrass carbon?
● create incentives for coastal conservation and restoration activities
● create disincentives to damage coastal ecosystems
Better to conserve than restoreBetter to conserve than restore
● Conserve = Dual benefit
● More efficient to sustainably manage than to allow loss and then attempt to re-colonise
● Restoration may be necessary
wikipedia wikipedia
Past methods of protecting carbonPast methods of protecting carbon
● Kyoto Protocol (1997)– Countries agreed to limit GHG emissions
• “flexible mechanisms” to meet these limits• Annual inventory• Doesn’t include coastal wetlands
● Copenhagen Accord (2009)– Ratify REDD
● Cancun Agreement (2010)– Ratify REDD+ which includes mangroves (not seagrass)– Blue Carbon recognised
International carbon creditsInternational carbon credits
● finance to encourage sustainable management– Norway-Indonesia
● Australia-Indonesia Carbon Partnership
● Australia could buy Indonesian “ecosystem restoration concessions” – Australian Clean Energy Scheme
● How can seagrass be included in a carbon accounting scheme?
wikipedia
Seagrass carbon accountingSeagrass carbon accounting
● Does seagrass loss actually leads to increased atmospheric CO2?
● IPCC needs to recognise sediment-based C storage– above-ground biomass is easy to count and satellites can monitor
● Develop a seagrass carbon budget protocol:– quantification – verification of stock over time– how long does the carbon remain within the financial unit– estimate of risk of loosing stock (insurance)
● Engage with a carbon trading market – voluntary market already operational for mangrove (Blue Carbon)
How is IUCN helping this happen?How is IUCN helping this happen?
● creating political awareness
● helping NGO generate public awareness
● drafting policy for IPCC, such as REDD+
● establishing a international research and policy agenda
What can you do?What can you do?
● Ask questions about removal of local seagrasses
● Ask questions if you see seagrass dying
● Engage with community monitoring of seagrasses
● Support seagrass restoration programs
● Increase public/political awareness of Blue Carbon
Blue Carbon
Coastal Water Quality
Fish NurseriesMarine Biodiversity
Coastline and Beach Stabilization
Co-benefits of protecting seagrassCo-benefits of protecting seagrass
Source: Forest Trend
• Adapt to climate change
• Sustain community resilience and coastal livelihoods
AcknowledgementsAcknowledgements
Bring Back the Fish