Effects of ingestion of Kepone-contaminated food by juvenile blue crabs ( Callinectes sapidus Rathbun)

Abstract

Two long-term (65-day) laboratory experiments were conducted to investigate lethal and sublethal effects of ingestion of Kepone-contaminated food by juvenile blue crabs ( Callinectes sapidus Rathbun). Food was contaminated at Kepone levels found in blue crab food sources in the James River in Virginia. The levels ranged from non-detectable (0.02 μg/g) to 2.5 μg/g. The experimental temperature was 28°C during Experiment 1 and 21°C during Experiment II. In neither experiment were crab mortalities statistically different at any dose tested. This indicates a 65-day LD 50 in excess of 0.5 μg Kepone/crab per day, based on a feeding rate of 0.2 g, or 0.16 μg/g crab per day based on the mean crab wet weight at the beginning of the experiments. The highest Kepone dose tested in both experiments caused significant increases in crab metabolic rates, as measured by oxygen consumption, and crab excitability during feeding. At the higher temperature of Experiment I there was an inverse relationship between carapace thickness:width ratios and increasing Kepone dose. Biomagnification of Kepone by crabs to a whole body tissue concentration greater than that in their food occurred at the highest treatment level in Experiment I. Crab molting frequency and overall growth were not statistically different at any Kepone treatment in either experiment.