TROPHIC TRANSFER OF SEDIMENT-ASSOCIATED POLYCHLORINATED-BIPHENYLS FROM MEIOBENTHOS TO BOTTOM-FEEDING FISH

Experiments were conducted to examine the dynamics of the sediment-ass ociated polychlorinated biphenyl (PCB) Aroclor(R) 1254 using a benthic -based trophic transfer model (sediments to benthic copepods to juveni le fish). Field-collected benthic copepods were exposed to sublethal l evels of Aroclor 1254 in sediments for 96 h. Accumulation of PCB was m easured in the copepods; and these contaminated copepods were fed to t he juvenile fish predator Leiostomus xanthurus in uncontaminated sedim ents. After gut clearance, whole fish were homogenized and examined fo r PCB accumulation. Similar experiments with L. xanthurus in which mea ls of uncontaminated copepods were fed in PCB-contaminated sediments w ere conducted to determine the relative roles of contaminated sediment s and contaminated copepod prey ingestion to PCB transfer. Total PCB t ransfer as well as PCB congener group contributions were examined. A t otal of 30 congeners were grouped according to log K-ow increments and according to chlorine homologue groups. Copepods exposed to PCB-conta minated sediments to 90 mu g/g accumulated PCBs to 326 mu g/g dry weig ht. Accumulation of PCB in fish feeding in contaminated sediments was five times higher than that in fish feeding on contaminated prey in un contaminated sediments (p = 0.0498). In terms of congener patterns, lo g K-ow grouping provided clearer discrimination between groups. Congen er patterns were similar in PCB stock solution, sediments, and copepod s and were different in the two fish treatments. K-ow group relative a ccumulation patterns in fish were mixed. The chlorine homologue groups revealed that the fish preferentially accumulated the tetrachlorinate d congeners relative to copepods and sediments.