1979

Journal of Coastal Research, Special Issue 64, 2011

Journal of Coastal Research SI 64 pg - pg ICS2011 (Proceedings) Poland ISSN 0749-0208

Natural and social conditions of Princesa, a macrotidal sandy beach on the Amazon Coast of Brazil

N. I. S. Silva†, L. C. C. Pereira†*, A. Gorayeb‡, A. Vila-Concejo∞, R. C. Sousa†, N. E. Asp† and R. M. Costa† †Instituto de Estudos Costeiros, Universidade Federal do Pará, Bragança, 6600-000, Brazil. *Email: cajueiro@ufpa.br

‡Departamento de Geografia, Universidade Federal do Ceará, Fortaleza 60833-500, Brazil. Email: gorayeb@ufc.br

∞School of Geosciences, The University of Sydney, Sydney, 2006, Australia. E-mail: ana.vilaconcejo@sydney.edu.au

INTRODUCTION The 8,500 km of the Brazilian coastline is characterized by an

ample variety of landscapes and natural ecosystems. Seventeen of the 27 Brazilian states are located along its Atlantic seaboard, and account for almost 70% of the country’s population (190 million inhabitants, IBGE, 2010). While this coastal zone includes heavily urbanized regions, where economic activities such as ports, industries, and tourism have intensified over the past few decades (Pereira et al., 2007a; Andrade et al., 2010), it also encompasses vast, sparsely-populated areas with well-preserved ecosystem, such as mangroves and dune fields (Lara, 2003; Szlafsztein and Sterr, 2007).

The Amazon coast includes only three states – Amapá, Pará, and Maranhão – but makes up approximately 35% of the coastline of Brazil. This area includes one of the largest continuous tracts of mangrove forest in the world (Kjerfve and Lacerda, 1993), the discharge of dozens of rivers (including the Amazon), and a variety of environments, such as muddy and sandy beaches, coastal plains, salt and freshwater marshes, lagoons, islands, deltas and dune fields (Souza Filho et al., 2005). Within this coastal zone, socio-economic and environmental conflicts are caused

primarily by exploitation of natural resources, population growth, urbanization processes, unplanned land occupation and natural disasters (Szlafsztein, 2003, 2009; Pereira et al., 2007b, 2009a; Silva et al., 2009; Menezes et al., 2009; Andrade et al., 2010).

Local and regional governments have created a number of marine extractive reserves and environmental protection areas (EPAs) within the Amazon coastal zone, with the primary aim of reducing or eliminating anthropogenic impacts on these well-preserved ecosystems (Szlafsztein, 2009). Unfortunately, the Pará state coastal management program (GERCO-PA) has been relatively unsuccessful in comparison with the programs of other Brazilian states. Despite this, the development of effective public policies remains an essential priority for the region.

The present study focused on Princesa Beach on Maiandeua Island in the northeastern corner of the Brazilian state of Pará (Figure 1). This popular tourist beach is located within an EPA which presents a number of social and environmental problems. The aim of the present study was to analyze the impacts of natural events and human activities on the characteristics of the beach and provide local authorities with guidelines for the implementation of coastal management programs.

ABSTRACT

Silva, N.I.S., Pereira, L.C.C., Gorayeb, A., Vila-Concejo, A., R.C. Sousa, N.E. Asp and R.M. Costa. Natural and social conditions of Princesa, a macrotidal sandy beach on the Amazon Coast of Brazil. Journal of Coastal Research, SI 64 (Proceedings of the 11th International Coastal Symposium), 1979 – 1983. Szczecin, Poland, ISSN 0749-0208

This study took place at Princesa Beach, located in an area of environmental protection on the Amazon coast of Brazil. The aim was to evaluate the impact of natural processes and human activities on this macrotidal beach, and provide local authorities with guidelines for the implementation of a coastal management program. Data on social and natural variables were collected between November, 2008, and August, 2010. All amenities on the beach were identified and georeferenced using a GPS in August, 2010. Four campaigns of over 25 hours duration were conducted during spring tide periods November, 2008, and March, June, and September, 2009 for the collection of hydrodynamic and hydrologic data. Motorized vehicles are prohibited on the island. The waterfront of Princesa beach is characterized by the presence of a small number of buildings. The beach receives large numbers of visitors only during July and certain bank holidays. The recreational consumption of drugs constitutes the island’s main social problem. Climatic and hydrological conditions were the main factors responsible for the high water turbidity and dissolved oxygen levels, and elevated concentrations of chlorophyll a and dissolved nutrients. The study area was not adversely affected by thermotolerant coliform levels. In order to guarantee the environmental integrity of the beach over a long term, the authors suggest: (i) the construction of an adequate public sanitation system, (ii) creation of garbage recycling programs (to reduce refuse in the dunes), (iii) incentives for the development of ecotourism programs, (iv) regulation of land use, and (v) intervention for the control of recreational drug use.

ADITIONAL INDEX WORDS: Natural and anthropogenic conditions, management, Amazon beach.

Journal of Coastal Research SI 64 1979 - 1983 ICS2011 (Proceedings) Poland ISSN 0749-0208

1980

Journal of Coastal Research, Special Issue 64, 2011

Natural and social conditions in a macrotidal sandy beach

STUDY AREA The study site (Figure 1) is located within an EPA of 2,378 ha

and it is one of the Amazon coast’s most popular tourist destinations, especially during the month of July. Princesa is a scenic beach approximately 14 km long, located on Maiandeua Island, which is bordered by the Marapanim and Maracanã estuaries. Local environments include dunes, lagoons, and mangroves. The local inhabitants depend on subsistence fishing and agriculture, as well as handicrafts and tourism.

The local climate is equatorial humid with a mean annual

temperature of 26-27°C and annual precipitation of over 2,000 mm. Some 75-85% of this precipitation falls during the wet season, which is normally between January and June (Martorano et al., 1993 and INMET, 2010). The tides are semi-diurnal with a maximum range of 5.5 m (DHN, 2010).

This dissipative macrotidal sandy beach forms an elongated sandy ridge about 300-400 m wide, parallel to the shoreline in an east-west orientation, with a curved spit running northwest-southeast. Both erosive and accretive conditions were observed along the beach.

METHODS Natural variables (meteorology, hydrodynamics, hydrology,

and microbiology) were assessed between November, 2008, and

September, 2009. All public amenities (between P1 and P2, Figure 1) on the beach were also identified and georeferenced using a Garmin Etrex GPS. A photographic map of the study area was elaborated based on the coordinates recorded in the field by GPS, and photographic records of specific features. Georeferencing was conducted using the digital cartographic database created in 2007 by the Geomatics Department of the Pará Federal Technological Education Center (CEFET-PA) for the municipal planialtimetric survey and registration of urban areas of Maiandeua Island. Analytical tools of the Autocad 2006© package were used for georeferencing, vectorization of features and the final formatting of the figure.

Metereological data (wind and rainfall) were obtained from the National Meteorological Institute for the period between November, 2008, and September, 2009. Four campaigns of over 25 hours duration were conducted during spring tide periods in November, 2008, and March, June, and September, 2009. A mini-current meter, CTD, and wave and tide data loggers were fixed to the sea floor at a depth of 2.0 m in the subtidal zone and programmed to collect average data every 10 minutes. Samples of sub-surface water were collected by Niskin oceanographic bottles every 3 hours for the measurement of hydrological data (pH, turbidity and dissolved nutrients, chlorophyll a and thermotolerant coliforms). Turbidity and pH were then determined in the laboratory. Dissolved oxygen concentrations were measured

Figure 1. Study area, showing Brazil (A), Amazon littoral (B), Northern Pará coast (C), Maiandeua island (D) and Princesa beach (E).

Journal of Coastal Research, Special Issue 64, 2011

Natural and social conditions in a macrotidal sandy beach

STUDY AREA The study site (Figure 1) is located within an EPA of 2,378 ha

and it is one of the Amazon coast’s most popular tourist destinations, especially during the month of July. Princesa is a scenic beach approximately 14 km long, located on Maiandeua Island, which is bordered by the Marapanim and Maracanã estuaries. Local environments include dunes, lagoons, and mangroves. The local inhabitants depend on subsistence fishing and agriculture, as well as handicrafts and tourism.

The local climate is equatorial humid with a mean annual

temperature of 26-27°C and annual precipitation of over 2,000 mm. Some 75-85% of this precipitation falls during the wet season, which is normally between January and June (Martorano et al., 1993 and INMET, 2010). The tides are semi-diurnal with a maximum range of 5.5 m (DHN, 2010).

This dissipative macrotidal sandy beach forms an elongated sandy ridge about 300-400 m wide, parallel to the shoreline in an east-west orientation, with a curved spit running northwest-southeast. Both erosive and accretive conditions were observed along the beach.

METHODS Natural variables (meteorology, hydrodynamics, hydrology,

and microbiology) were assessed between November, 2008, and

September, 2009. All public amenities (between P1 and P2, Figure 1) on the beach were also identified and georeferenced using a Garmin Etrex GPS. A photographic map of the study area was elaborated based on the coordinates recorded in the field by GPS, and photographic records of specific features. Georeferencing was conducted using the digital cartographic database created in 2007 by the Geomatics Department of the Pará Federal Technological Education Center (CEFET-PA) for the municipal planialtimetric survey and registration of urban areas of Maiandeua Island. Analytical tools of the Autocad 2006© package were used for georeferencing, vectorization of features and the final formatting of the figure.

Metereological data (wind and rainfall) were obtained from the National Meteorological Institute for the period between November, 2008, and September, 2009. Four campaigns of over 25 hours duration were conducted during spring tide periods in November, 2008, and March, June, and September, 2009. A mini-current meter, CTD, and wave and tide data loggers were fixed to the sea floor at a depth of 2.0 m in the subtidal zone and programmed to collect average data every 10 minutes. Samples of sub-surface water were collected by Niskin oceanographic bottles every 3 hours for the measurement of hydrological data (pH, turbidity and dissolved nutrients, chlorophyll a and thermotolerant coliforms). Turbidity and pH were then determined in the laboratory. Dissolved oxygen concentrations were measured

Figure 1. Study area, showing Brazil (A), Amazon littoral (B), Northern Pará coast (C), Maiandeua island (D) and Princesa beach (E).

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according to the Winkler method (Strickland and Parsons, 1968), and nutrients according to Strickland and Parsons (1972) and Grasshoff et al. (1983). Chlorophyll a content and thermotolerant coliform concentrations were determined by the methods of Strickland and Parsons (1972) and APHA (2004), respectively.

RESULTS AND DISCUSSION

Environmental Features The Amazon coast is characterized by high solar radiation,

high and stable temperatures, strong winds dominated by the easterly trades, and some of the highest rainfall rates in the world (Marengo, 1995; Geyer et al., 1996; Nittrouer and DeMaster, 1996). During the study period, annual precipitation was over 2,000 mm. The strongest winds, mainly from the northeast, were recorded during the dry season (monthly average up to 9.3 m/s), while moderate winds (less than 6 m/s) from the northeast and southeast were recorded during the wet season.

Four distinct natural scenarios were recorded in terms of hydrodynamic and hydrological conditions: (i) November, 2008 (late dry season: lowest fluvial discharge) was characterized by high hydrodynamic energy, with strong tidal currents (up to 0.8 m/s) and high waves (up to 1.2 m), the highest salinity (up to 35 psu) and pH (up to 8.5), and the lowest dissolved nutrient concentrations and turbidity (15.81 UT); (ii) March, 2009 (wet season: equinoctial spring tide) was also characterized by high hydrodynamic energy, including waves of up to 1.3 m in height and strong tidal currents (up to 0.8 m/s), as well as a tide height of 5.8 m, in addition to the highest concentrations of chlorophyll a (up to 67.6 mg/m³) and nitrates (up to 28.87 µmol/l); (iii) June, 2009 (late wet season: highest fluvial discharge) was characterized by relatively low hydrodynamic energy, with tides of 4.3 m and tidal currents up to 0.64 m/s, the lowest salinity (4.0 psu) and pH (6.9), and the highest silicate concentrations (up to 348.9 µmol/l); (iv) September, 2009 (dry season: equinoctial spring tide), hydrodynamic energy was also high (tide height of 5.8 m and tidal currents of 0.8 m/s), and the highest phosphate (up to 0.92 µmol/l) and nitrite (up to 0.49 µmol/l) concentrations were also recorded.

The local high hydrodynamic energy is a consequence of the macrotidal conditions that in general result in strong tidal currents (Beardsley et al., 1995), mainly during the equinoctial periods. In addition, the discharge of the Amazon River and dozens of other estuaries onto the coastal shelf form a vast and complex marine-estuarine system characterized by unique levels of sediment run-off, dissolved nutrients and organic material unlike those found anywhere else on the planet (Meade et al., 1985; Geyer et al., 1996). These natural processes are among the principal factors responsible for variations in nutrient concentrations, turbidity and salinity, and the formation of phytoplankton blooms on the Amazon coast and continental platform (DeMaster et al., 1996; Santos et al., 2008).

The maximum thermotolerant coliform concentration recorded during the present study was 450 MNP/100ml, which does not represent a significant threat to the quality of the water, according to the criteria of the Brazilian Environment Council, CONAMA (2005), indicating that the beach is more than adequate for bathing. This appears to indicate the absence of significant anthropogenic impacts, although natural conditions, such as the high levels of fluvial discharge, are responsible for the inadequate turbidity values, according to CONAMA (2005) criteria.

Social Aspects Motorized vehicles are prohibited on the island, and the only

wheeled transport is provided by donkey carts (Figure 2A). The waterfront of Princesa beach is characterized by its sparse infrastructure (Table 1), with only 22 bars built on the dunes and intertidal zone (Figure 2B). Under the EPA management, the construction of hotels or other buildings, except fishermen’s huts, is strictly prohibited.

The relative inaccessibility of the beach tends to restrict visitation except during the peak vacation season (July) and some bank holidays (Figure 2C). The island can only be reached by boat. There are no campgrounds on the island, although Algodoal village offers a selection of lodgings. The beach is patrolled by lifeguards only in July (Figure 2D). Sewage disposal is based on the few precarious cesspits built in the dunes or intertidal zone (Figure 2E), while refuse is dumped in the dunes (Figure 2F). Toilets and showers are only available in the bars, and their use is restricted to customers. The recreational consumption of drugs such as marijuana and cocaine constitutes the island’s main social problem.

Fishing and tourism are the principal economic activities within the Amazon coastal zone. Pará has good potential for tourism, but the development of this industry is limited primarily by the lack of adequate infrastructure. Initiatives have been implemented at municipal, state, and federal government levels, providing economic incentives for the improvement of services and infrastructure while maintaining the natural beauty of the region’s beaches (Szlafsztein and Sterr, 2007), but the results have been slow in coming.

The unregulated occupation of land, and the lack of services and infrastructure are the principal factors underpinning the social and environmental problems that characterize this sector of the Amazon region (Krause and Glaser, 2003; Pereira et al., 2007b, 2009b; Souza Filho et al., 2006; Menezes et al., 2009). The main problems observed in the study area – i.e., the lack of an adequate public water supply, sanitation system, and refuse collection – are typical of the region as a whole.

These problems are intensified during the July vacation period, when the beach is visited by large numbers of tourists, with a concomitant increase in the production of sewage and refuse. A number of environmental education programs have been implemented on Maiandeua Island, although there is an urgent need for the active involvement of local and regional governments for the improvement of existing infrastructure, and the implantation of sustainable development initiatives. Overall, the development of a coastal management plan should be the main priority for local authorities.

Table 1. Public amenities and other infrastructure identified on Princesa beach, Maiandeua Island, Pará.

Item Number

Refuse bin 20

Lamp post 49

Bar 22

Well 6

Cesspit 2

Fishermen’s hut 2

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Journal of Coastal Research, Special Issue 64, 2011

Natural and social conditions in a macrotidal sandy beach

FINAL CONSIDERATIONS Climatic and hydrological conditions were the main factors

responsible for the high water turbidity and dissolved oxygen levels, and the elevated concentrations of chlorophyll a and dissolved nutrients recorded during the study. Local residents and beachgoers have been targeted by a number of environmental education programs, and some of the local ecological and social problems have been resolved or mitigated. However, other

problems, such as drug abuse and the inadequate disposal of sewage and refuse require effective intervention from local authorities. In order to guarantee the environmental integrity of the beach over a long term, the authors suggest: (i) the construction of an adequate public sanitation system, (ii) creation of garbage recycling programs (to reduce refuse in the dunes), (iii) incentives for the development of ecotourism programs, (iv) regulation of land use, and (v) intervention for the control of recreational drug use.

Figure 2. General conditions recorded in Princesa beach.

Journal of Coastal Research, Special Issue 64, 2011

Natural and social conditions in a macrotidal sandy beach

FINAL CONSIDERATIONS Climatic and hydrological conditions were the main factors

responsible for the high water turbidity and dissolved oxygen levels, and the elevated concentrations of chlorophyll a and dissolved nutrients recorded during the study. Local residents and beachgoers have been targeted by a number of environmental education programs, and some of the local ecological and social problems have been resolved or mitigated. However, other

problems, such as drug abuse and the inadequate disposal of sewage and refuse require effective intervention from local authorities. In order to guarantee the environmental integrity of the beach over a long term, the authors suggest: (i) the construction of an adequate public sanitation system, (ii) creation of garbage recycling programs (to reduce refuse in the dunes), (iii) incentives for the development of ecotourism programs, (iv) regulation of land use, and (v) intervention for the control of recreational drug use.

Figure 2. General conditions recorded in Princesa beach.

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Silva et al.

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ACKNOWLEDGEMENTS This study was financed by FAPESPA (Fundação de Amparo

à Pesquisa do Estado do Pará) through universal project no. 115/2008. The authors would also like to thank CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnologia), CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior) and FAPESPA for research grants. We are also indebted to Stephen Ferrari for careful correction of the English.