MTN 115:13-14 Tarballs and Early Life Stages of Sea Turtles in Paraíba, Brazil

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Tarballs and Early Life Stages of Sea Turtles in Paraíba, Brazil

Robson G. Santos & Erich F. Mariano
Departamento de Sistemática e Ecologia, Centro de Ciências Exatas e da Natureza, Universidade Federal da Paraíba, Campus I, Cidade Universitária, João Pessoa, Paraíba 58059-900, Brazil (E-mail: robsongsantos@gmail.com, efmariano@gmail.com)

Although not ranked as one of the main threats to the sea turtles, oil exploration and transport are potential sources of direct and indirect threats to these animals (NMFS 1991; NOAA 2003). Large oil spills attract much attention of the media due to the massive damage they cause, but these events are not frequent. In contrast, smaller scale contamination events not highlighted by the media, but they are more frequent and the additive value of may have considerable impact. Tarballs are common byproducts of maritime operations, often a result of, illegal at-sea discharge. They are found in every ocean and convergences zones can aggregate them. (NOAA 2003). Here we report the stranding of a dead juvenile green turtle, Chelonia mydas, with curve carapace length (CCL) of 13.5 cm, completely covered by tarballs (images available at <https://seaturtle.org/cgi-bin/imagelib/index.pl?photo=1410>) on August 29 2004, in Bessa beach, João Pessoa, Paraíba, Brazil. Unfortunately, it was not possible to collect the gastric contents of the animal.

The specimen belongs to the most vulnerable life stage to tarballs, hatchlings and post-hatchlings. This vulnerability is related to their relative small size; to their low motility, that lead them to concentrate in convergence zones, where the oil also tends to concentrate; and to their swimming mode, surface swimming, which increases their chances of interaction. In Florida convergence zones, from 103 post-hatchling analyzed, tar was found in 65 individuals (Lohoefener et al. 1989). Witherington (1994) showed that 34% of post-hatchling at “weed lines” off the Florida coast had tar in their mouths or esophagi. Lutz (1989) reported that hatchlings have been found dead, apparently starved to death, with their beaks and esophagi blocked with tarballs.

This specimen also represents a register of the occurrence of a size class that has not been found in Paraíba yet. The mean CCL size of green turtles found stranded in this area was 56.5 cm (2002-2003) and the smallest was 29.3 cm (Mascarenhas et al. 2005). Until the current specimen was found, there were only unpublished fishermen reports regarding the presence of individuals of this size class, captured in entanglement nets in the reefs close to the coast. The CCL of green turtles recruiting to the neritic zone is between 20-35 cm (Bjorndal 1997; Musick & Limpus 1997) with smaller individuals thought to reside in the pelagic zone (Carr 1987). The occurrence of this specimen and the fishermen reports Mandate further investigation as to the possibility of small juvenile green turtles in the neritic.

Acknowledgements: Thanks to Louisa Sousa for English support. We thank the editors and the two anonymous referees for their relevant suggestions.

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