Are Catfish (Ariidae) Effective Bioindicators for Pb, Cd, Hg, Cu and Zn?

Ariidae catfish species are numerically abundant along the coast of Brazil. Their benthic habits and broad spectrum diets make them good potential candidates for sub-lethal biomonitoring studies. In this study, we assess the levels of various metal contaminants (Pb, Cd, Hg, Cu and Zn) in the muscle tissues of two Ariidae species, Cathorops spixii and Genidens genidens, from three sites in So Paulo State, Southeast Brazil: two polluted sites in the Santos-So Vicente estuary and a relatively unpolluted site in the Canan,ia estuary. The Zn levels observed in the polluted areas in the Santos-So Vicente estuary were similar to those obtained for Ariidae from the reference site in Canan,ia. The concentrations of Hg and Cu in the muscle tissue of both fish species were higher in individuals from the Santos-So Vicente than those from the Canan,ia estuary. Both Ariidae species were observed to accumulate the Cu, Zn and Hg in their tissues; however C. spixii showed a more stable response suggesting its potential utility as a bioindicator species. The Zn and Cu concentrations probably reflect normal levels without a significant influence of anthropogenic contamination. The levels of Cd and Pb in muscle tissue of C. spixii and G. genidens were relatively low, but the PCA indicated the presence of the levels of these metals in the reference area (thereby supporting the need for monitoring in Canan,ia estuary). The detection of Hg in fish from Santos-So Vicente and from the unpolluted site (Canan,ia) is of particular concern as scientists frequently use this area as a reference site for biomonitoring studies on the Southwest coast of Brazil.