Hepatic histopathological findings in Ariidae Cathorops spixii submitted to anthropogenic metal exposure in two Brazilian estuaries

Abstract

Histopathological lesions are used as biomarkers of contamination by organic and inorganic chemical compounds in the aquatic systems and can reflect chronic effects in sentinel species. Previous work demonstrated the ability of the catfish Cathorops spixii to be an efficient bioindicator species for metals contamination. Cananéia estuary is considered an area of environmental protection, and UNESCO World Heritage Site (WHS), and as such, several biomonitoring studies in the São Paulo State, Brazil, use this estuary as a reference environment due to the fact that it shows very little human influence. However, in recent years, several studies have been indicating the presence of some toxic metals, for instance mercury (Hg) and lead (Pb). Santos-São Vicente estuary has a long history of contamination and release of pollutants, for instance metals such as Pb, Cd, Ni, Mn, Cu and Hg as a consequence of different anthropogenic activities such as petrochemical, metallurgical and harbor. In the present work, histopathological lesions in liver were investigated in the Ariidae Cathorops spixii from Cananéia estuary and in two sites affected by industrial and domestic sewage disposal, in order to verify the possible impact of the introduction of metals to the local fish species. Fish were collected in Cananéia and in two sites of the Santos São-Vicente estuary subjected to different anthropogenic influence (industrial and domestic sewage disposal). Biometric data (total length –TL- and total weight -TW- of each fish) was obtained and the fish dissected by collection of the hepatic liver to histopathological and metals analysis. Analyses of Hg was performed by FIA-CV AAS and Pb, Cd, Cu, Mn and Ni concentrations were determined by ICP MS. Fish from Cananéia showed higher levels of Mn (80%) and Cu (66%). The most important injuries observed in individuals from the impacted areas (industrial and domestic sewage) were the presence of necrotic areas, hepatitis focal, vacuolization and rupture of blood vessels. The occurrences of lesions were significantly higher in individuals from domestic and industrial area than in fish from Cananéia estuary (p>0.05).