EFFECTS OF SUBLETHAL COPPER EXPOSURE ON COPPER ACCUMULATION, FOOD-CONSUMPTION, GROWTH, ENERGY STORES, AND NUCLEIC-ACID CONTENT IN COMMON CARP

Juvenile common carp were exposed for 28 days to three different suble thal copper concentrations (0.20 mu M, 0.55 mu M, and 0.80 mu M). Food consumption was monitored on a daily basis during the exposure period , while growth, copper accumulation, energy stores, and nucleic acid c ontents were assessed weekly. Copper exposure to 0.80 mu M affected bo th growth and feeding behavior in common carp. At 0.55 mu M, growth wa s affected despite normal food consumption. Even at the lowest copper concentration (0.20 mu M), metabolic demand for the fish increased, ch allenging the carp with an increased demand for food. Copper accumulat ion mainly occurred in the liver, reaching an equilibrium between upta ke and excretion after 1 month of exposure. Substantial biochemical ch anges were observed at the two highest copper exposure concentrations, but the correlation between growth rate and RNA:DNA ratio was poor co nsidering the substantial differences in growth rate. The use of the R NA:DNA ratio as a sensitive biomarker is questioned.