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Baixada Santista encompasses the municipalities of Santos, São Vicente, Cubatão, Praia Grande, Mongaguá, Itanhaém, Peruíbe, Guarujá and Bertioga (Fig. 1). It suffers from a host of environmental problems, mainly due to the large concentration of human inhabitants, and ongoing industrial development, including natural resource extraction and port expansion (Silva 2010). In association with this is the issue of increased pollution and marine debris, which poses a threat to marine animals that, occur in this region (Tourinho et al. 2010, Schuyler et al. 2012).

Figure 1. Map of study area in Baixada Santista. Abbreviations indicate municipalities that compose the region. Modified of CEM/Cebrap-Centro de Estudos da Metrópole-2008.

To better understand the diversity and relative occurrence of different sea turtle species in the region, we monitored the coast for reported stranded turtles from June 2010 to June 2011. We were alerted to stranded turtles through calls from concerned citizens or authorities such as IBAMA and the fire department. In each case, we collected photos and biometric data according to the method adopted by TAMAR-ICMBio, and in cases of dead animals, we necropsied the animal following Wyneken (2001).

We responded to 65 stranded sea turtles in the study area. Of these records, 52 animals were found dead and 13 were still alive, but subsequently died. Three species were recorded: Chelonia mydas, Caretta caretta and Eretmochelys imbricata. All of 65 individuals were all classified as juveniles and subadults (Bjorndal et al. 1994; Moreira et al. 1994, Balptistotte et. al. 2003, Table 1).

With respect to the state of decomposition of the animals, 37 turtles were classified as fresh dead, 12 were moderately decomposed and 16 were highly decomposed.

The majority of stranded turtles occurred in the winter (June to September, 50.8% of records), while Bugoni et al. (2001), reported that more stranded turtles occurred during the summer months (October to March). The most commonly encountered turtle was the green turtle (Table 1).

Table 1. Biometric data (in cm) for stranded turtles found in Baixada Santista, Brazil, from June 2010-June 2011. CCL = curved carapace length, CCW = curved carapace width.

The Praia Grande municipality had the highest number of strandings (40%), followed by the Guarujá municipality (30.8%), São Vicente (20%), Bertioga (7.7%) and Mongaguá (1.5%). The increased density of strandings in the cities of Praia Grande, Guarujá and São Vicente is probably related to the co-occurrence of the rocky shoreline covered by seaweed that may serve as foraging habitat for green sea turtles.

We necropsied 65 animals, of all three species. We found 78.5% of the study animals had anthropogenic waste in their digestive tract (Table 2), including various types of plastic (candy wrappers, bags, plastic cups and other, classified only as plastic or hard plastic), nylon thread and fishing line, balloons, cigarette packages, pieces of wire, pieces of fabric, Styrofoam and kite pieces.

Table 2. Frequencies for each residue type found in sea turtles’ digestive tracts.

The ingestion of solid waste may occur when turtles confuse waste with natural food items or they may accidentally ingest waste together with food (Balazs 1985; Laist 1987). The waste may obstruct the animal’s gastro-intestinal tract, possibly leading to death, or causing sub-lethal effects such as damage to the walls of the gastro-intestinal tract (Bjorndal 1997), reduced nutritional gain (Mccauley & Bjorndal 1999), increased time of food in the digestive system and changes in buoyancy due to accumulation of gas in the intestines (George 1997). Oceanic juveniles are often exposed to marine debris in convergence zones, and most turtle species are exposed in coastal habitats where they feed (Thomas et al. 2002).

We found that 62.3% of our study turtles had plastic in them, similar to the rate of 60.5% reported by Bugoni et al. (2001) for sea turtles found in Rio Grande do Sul state at the southern end of the Brazilian coastline. In some cases, we found that one animal had more than one type of plastic in its digestive tract, pointing to widespread occurrence of plastics in the marine environment and its likely negative impacts (Derraik 2002).

During necropsies, we identified food items in 20 green turtles, largely seaweeds and mangrove plants, but also some fish and crustaceans. In a single loggerhead, we found a remnant of the shell of a mollusc and digested parts of fish in the intestine, typical food items of this species (Bjorndal 1997). The presence of the food items in the digestive tracts of these animals indicates that Baixada Santista serves as a feeding ground in the region, and we suggest conservation measures are needed to protect the habitat and the animals that use it (Bjorndal 1999).

The Baixada Santista coastal ecosystem suffers from anthropic impacts upon its fauna and flora, which may have consequences on human health. Some environmental problems include intense industrial, port and domestic effluents placed indiscriminately into rivers and estuaries, as well as deforestation and a lack of zoning laws for careful development in areas along the outskirts of towns (Hortelani et al. 2005). Other human activities such as large-scale fisheries may also cause negative impacts to sea turtles, contributing to an increase in mortality of sea turtle populations.

The intensely urbanized beaches in Baixada Santista are subject to large streams of waste, which are eventually deposited in the coastal seaweed banks used by green sea turtles for food. Furthermore, the human presence may cause other damage, such as the collisions of vessels with animals and/or disturbing them on foraging grounds (Short & Wyllie-Echeverria 1996; Hazel et al. 2007). Finally, dense human presence also complicates the recording of stranding, because carcasses are often collected by people to use as ornaments (Campbell 2002). Therefore, it is necessary to conduct an intense awareness and environmental education campaign in the region, with the objectives to improve local sanitary conditions and raise awareness about sea turtles. This in turn would help ensure that stranded sea turtles would be reported quickly to the appropriate authorities, so that they can be salvaged or rehabilitated as needed.

Our study indicates the presence of these animals in the region and its use as a feeding area by green turtles. We suggest that the development of an environmental education programs and ongoing monitoring of the beaches in this region are important measures needed to generate a more complete description of the animals found in this area. In-water work with sea turtles in the region may also shed light on their behavior and migrations, may offer more information on population size, using mark-recapture techniques.

Acknowledgements. The authors would like to thank the IBAMA (SISBIO 16988-2) and the Fire Department of Santos.

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