Cadmium concentrations in Sotalia guianensis (Van Bénéden, 1864) in a tropical estuary, southeast of Brazil.

Abstract

Cadmium concentrations were assessed in the hepatic tissues of 27 dolphins of the Sotalia guianensis species that were found stranded in the estuary Complexo Estuarino Lagunar de Cananéia-Iguape, southeast of Brazil, between the years 2009 and 2012. The samples’ digestion was performed through acid digestion with HNO3 and the quantification was held by flame atomic absorption spectrometry (FAAS). For 11 of the sampled animals, concentrations did not exceed the limit of quantification of 0.1µg/g-1 proposed by the method. Nevertheless, low values of the metal were commonly found in the tissues of estuarine dolphins on the Brazilian coast. In this research, the concentrations varied from 0.13 to 1.79µg/g-1 (wet weight), for a total average of 0.39µg/g-1 which is in accord with those described in literature for the specie. No differences were observed in the accumulation of cadmium between sexes, age classes nor correlation between the curvilinear length and the accumulation of the metal. The study highlights the flow through the trophic chain as being an important factor for the accumulation of Cd and supports the use of the species as a bio-indicator of the environmental quality of its habitat, due to its biological and ecological peculiarities.