BIOCONCENTRATION AND BIOMAGNIFICATION OF METHYLMERCURY IN GUANABARA BAY, RIO DE JANEIRO

BIOCONCENTRATION AND BIOMAGNIFICATION OF METHYLMERCURY IN GUANABARA BAY, RIO DE JANEIRO. Methylmercury was determined in water and aquatic biota from Guanabara Bay. Trophic transfer of methylmercury was observed between trophic levels from prey (microplankton, mesoplankton and fish with different feeding habits) to top predator (pelagic - demersal fish). Top predator fish presented the highest methylmercury concentrations (320.3 +/- 150.7 mu g kg(-1) dry wt.), whereas microplankton presented the lowest (8.9 +/- 3.3 mu g kg(-1) dry wt.). The successive amplification of methylmercury concentrations and its bioconcentration factor with increasing trophic levels from base to top indicate that biomagnification may be occurring along the food web. Results suggest the importance of feeding habits and trophic level in the bioaccumulation of methylmercury by aquatic biota.