PARENT SESSION

PT03 Persistent Organic Pollutants (POPs)
Exhibit Hall
8:00 AM - Tuesday

(PT016) Consequences of body weight loss on hepatic organochlorine and tributyltin concentrations and EROD activity in St. Lawrence Estuary Atlantic tomcod.

Couillard, C.¹, Lebeuf, M.¹, Pelletier, É.², ¹ Department of Fisheries and Oceans, Mont-Joli, Québec, Canada² Université du Québec à Rimouski, Rimouski, Québec, Canada

ABSTRACT- Changes in contaminant concentrations and distribution associated with acute body weight loss during winter may contribute to impaired health and reproduction in Atlantic tomcod (Microgadus tomcod) from the St. Lawrence Estuary (Quebec, Canada). A reduction of EROD activity with age was observed in these fish and was associated with severe emaciation of an important proportion of large-sized fish. In this study, we investigate the effect of size/age and emaciation (hepatic lipids<30 %) on polychlorinated biphenyls (PCB) concentrations and congener profiles and chlorinated pesticides concentrations in female tomcod collected in the St. Lawrence Estuary in May 2002. Hepatic concentrations of tributyltin (TBT) and metabolites were also examined in female tomcod collected in May 2001. The relationships between concentrations of contaminants and EROD activity in the liver were determined. PCB concentrations or congener profiles did not vary in function of body length. Lower proportions and lower wet-weight concentrations of the less lipophilic congeners (Log K_ow<7) were observed in emaciated fish. Lipid-based concentrations of PCBs (5-times higher), mirex (10-times higher), DDTs (3-times higher) and chlordanes (2-times higher) increased in emaciated fish compared to non-emaciated fish and were negatively correlated to percentages of lipids in the liver. As percentage of lipids decreased from 71 % to 2 %, PCBs varied from 400 to 6000 ng/g lipid and mirex from 1 to 93 ng/g lipid. Concentrations of TBT (30 to 950 ng/g lipid) were not related to body length, did not differ significantly between emaciated and non-emaciated fish but were negatively correlated to lipid content. EROD activity was inversely correlated to both lipid-based concentrations of organochlorine contaminants and lipid content and was not correlated to TBT concentrations. Thus, the concentrations and composition of contaminants are altered in the liver of emaciated fish and these changes may potentially affect fish health.

Key words: weight loss, Microgadus tomcod, contaminant, EROD