METAL CONCENTRATIONS IN FISH OTOLITHS IN RELATION TO BODY-COMPOSITIONAFTER LABORATORY EXPOSURE TO MERCURY AND LEAD

Juvenile sand gobies Pomatoschistus minutus, plaice Pleuronectes plate ssa, and sole Solea solea were exposed to high or low levels of mercur y or lead for 45 d in the laboratory. Points on the otolith correspond ing to the core (pre-treatment), the start of exposure, midway through the exposure, and the termination of exposure were sampled and analys ed by laser ablation-inductively coupled plasma mass spectrometry (LA- ICPMS). There were significant increases in the metal content of the g oby and sole otoliths after exposure to mercury or lead, and the diffe rences between the treatment levels for each element were significant. Plaice otoliths showed Little increase in metal accumulation, and the difference between treatments was not significant. The relationship b etween exposure level, otolith metal concentration, and the metal conc entration in fish muscle tissue was complex. In general, lead accumula ted faster in the otolith and uptake was higher at low exposure levels . Mercury concentrations in fish tissue generally paralleled the conce ntration measured in the otoliths and the exposure level. Lead concent rations in fish otoliths were inversely related to tissue concentratio ns.