Ictiofauna e bioacumulação de metais pesados na cadeia trófica, Rio Gramame, bacia do Rio Gramame Paraíba

• Autor(a) principal: Souza, Jane Enisa Ribeiro Torelli de
• Data de Publicação: 2013
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UFPB
• Texto Completo: https://repositorio.ufpb.br/jspui/handle/tede/4140
• topic: Ictioafauna; Estrutura trófica; Bioacumulação de metais pesados; Ictihyofauna; Trophic structure; Bioaccumulation of heavy metals; CIENCIAS BIOLOGICAS::ZOOLOGIA

The objective of this study was to determine the fish diversity and the bioaccumulation of heavy metals in the trophic chain of River Gramame in the hydrographic basin of River Gramame, Paraíba. The fish composition was determined by collecting fish from 10 specific areas along the River Gramame, utilizing diversified fishery techniques, during the dry and rainy seasons of 2010 to 2011. The fish collected was transported to the Laboratory of Aquatic Ecology (DSE/CCEN/UFPB), where biometry of fish was carried out (total weight and standard length), to determine the type of growth and condition factor, with a view to compare these parameters in contaminated fish. The food habits of the fish were determined by analyzing the stomach contents using the frequency of occurrence method. This was useful to understand the food chain which served as a base for the study of bioaccumulation of heavy metals in fish. The ecological diversity was determined from the indices of diversity (Shannon-Wiener), equitability (Simpson), similarity (Jaccard) and species richness. The concentrations of heavy metals (Pb, Zn, Cd, Cu) in the fish muscle were quantified by square wave voltammetry (VOQ) in a potentiostat/galvanostat in the Laboratory of Environmental Chemical Studies (DQ/CCEN/UFPB), and total mercury (Hg) by atomic absorption spectrometry with cold vapor (CV AAS) in IPEN/USP/SP. The fish composition of the upstream area showed lower taxa than the downstream area (16 to 26 genera and 17 to 27 species, respectively). The abundant species were, Cichla ocellaris (55.39%±28.96), Metynnis lippincottiannus (20.34%±13.4), Prochilodus brevis (16.63%±11.36) and Hoplias malabaricus (13.33%±7.57), during both seasons of the year. The indices of diversity showed differences between the rainy and dry seasons and the upstream and the downstream areas of the reservoir (H =1.3075; H =1.538), (H =1.6497; H =1.3553), with richness represented (17 to 26 and 18 to 22 species respectively) and a heterogeneous distribution of species (J =0.52269 and J =0.38618 respectively), due to the dominance of C. ocellaris in upstream and of M. lippincottianus in downstream of the reservoir. The growth rate of most of the species analyzed showed young individuals, indicating negative allometric growth. The diet of the species showed little difference, indicating mostly generalist food habits of fish along River Gramame. The principal component analysis (PCA) expressed a tendency in upstream and downstream areas of the reservoir to differ in terms of heavy metal accumulation in the trophic chain. A major contamination of total mercury was registered in the upstream area, while there was lead and zinc contamination in the downstream area of the reservoir. It could be concluded that along River Gramame there is major dominance of exotic species with a low diversity of native species. The feeding habits of the fish species showed a generalist tendency, with more omnivores. High heavy metal concentration was registered in the omnivores, indicating biomagnifications of toxic elements among the studied species.