THE EFFECTS OF EXPOSURE DURATION AND FEEDING STATUS ON FISH BILE METABOLITES - IMPLICATIONS FOR BIOMONITORING

Biliary metabolites of 2-chlorosyringaldehyde (2-CSA), the major chlor inated phenol found in chlorine dioxide bleached eucalypt pulp effluen t, have been found to be sensitive biomarkers of effluent exposure in the sand flathead (Platycephalus bassensis), Before this method of bio monitoring can be applied in the field, the influences of exposure dur ation, depuration time, and fish feeding status on the level of this m etabolite should be determined, In this study, sand flathead were expo sed to a measured concentration of 0.3 mu g/l of 2-CSA for 1, 2, 4, 8, 12, or 16 days, Fish previously exposed to 2-CSA were then held in se a-water alone for 1, 2, 3, 4, or 6 days, Fish were fed ad libitum thro ughout the experiment, and the fullness of the fish's stomach at the t ime of sampling was noted, There were no effects of exposure on biotra nsformation enzyme activities, either between exposure times or betwee n the exposure and depuration periods, The major metabolite of 2-CSA, 2-chloro-4-hydroxy-3,5-dimethoxybenzylalcohol (2-CB-OH), was first det ected in the bile of some fish sampled after 24 h of exposure, and the mean concentration of 2-CB-OH in the bile increased over the exposure period, The mean concentration (+/-SE) of 2-CB-OH in the bile was str ongly influenced by fish feeding status, being 94+/-18 ng/ml bile in f ish with empty stomachs and undetectable in fish with full stomachs, B ile volume was also influenced by fish feeding status, being greatest in fish with empty stomachs at the time of sampling, Results indicate that the feeding status of fish should be taken into consideration whe n using biliary metabolites as biomarkers of effluent exposure in the field, and methods to establish this are discussed, (C) 1998 Academic Press.