A tartaruga-verde (Chelonia mydas, Linnaeus,1758) e os elementos-traço na costa do Brasil

Abstract

The green sea turtle (Chelonia mydas) is one of the five species of sea turtles occurring in Brazil. It is a cosmopolitan species that inhabits tropical and subtropical waters. Green turtles present a habitat used shift in juvenile life stage. Young turtles move from oceanic to coastal habitat and from an omnivorous to an herbivorous diet. This study is divided into two sections: one that addresses to the total mercury (HgT) determination in 241 juvenile green sea turtles from seven Brazilian coastal states (Ceara, Rio Grande do Norte, Rio de Janeiro, Sao Paulo, Parana, Santa Catarina and Rio Grande do Sul) and one that addresses to five chemicals elements concentrations (Ag, Cd, Hg, Se and Cu) in 33 green sea turtles from Paraná State, southern Brazil. Analyses were performed in liver, kidney and muscle in an atomic absorption spectrometry equipment with cold vapor generation for the mercury determination and electro thermal atomization in graphite furnace for the other elements. In both studies the HgT concentrations decreased overgrowth. The highest concentrations were found in liver and kidney and lower concentrations in muscle. Elements concentrations could not be related to body condition considering both index and category. HgT concentrations found in RJ are among the lowest values ever reported for the species. HgT concentration profile on Brazilian coast showed higher concentrations in the northeast and south regions and lower in the southeast. Cadmium values found in this study one of the highest ever reported for the species in the world, in all the tissues analyzed, which may be related to a diet rich in cephalopods. A higher concentration of HgT was found in raining station, coastal areas and in males and this is the first study that shows differences in mercury concentration related to sex in juvenile green sea turtles. Selenium showed a negative correlation with age in the liver and kidney. The decrease in concentration with age may be related to a specific metabolism mechanism of the element in green sea turtles. Cu concentrations were higher in the estuary that could indicate point sources inside the bays. Both studies contribute to the understanding of the dynamics of chemical elements in the food chain of a vulnerable species and present relevant information of contamination associated with biological data and location. This result can be used as a support for coastal resources management and in the species and ecosystems conservation