Hepatic Metal and Metallothionein Levels in a Potential Sentinel Teleost, Dules auriga, from a Southeastern Brazilian Estuary

The identification of estuarine sentinel species is of paramount importance. The potential of the species Dules auriga sampled from Guanabara Bay, Brazil regarding metal contamination was assessed. Hepatic metallothionein (MT) and Fe, Zn, Cu, Mn, Cd and Ag concentrations were determined in cytosolic fractions (S50 and HT S50) by polarography and ICP-OES, respectively. HT S50 Fe, Mn and Zn were lower than in the S50 fraction, indicating MT-detoxification. MT was correlated to HT S50 Zn, indicating Zn homeostasis. Zn was negatively correlated to weight (TW) and length (TL), suggesting environmental Zn influence. A moderate negative correlation between HT S50 Cu and the condition factor (CF) was observed, indicating that increasing environmental Cu concentrations may decrease D. auriga CF. Several inter-elemental correlations were observed. No MT, TW and TL correlations were found. Thus, MT variability is probably linked to environmental metal concentrations. D. auriga fulfills most sentinel requisites, and MT may be an adequate metal contamination biomarker in this species.