THE INFLUENCE OF STARVATION AND COPPER EXPOSURE ON THE COMPOSITION OFTHE DORSAL CARAPACE AND DISTRIBUTION OF TRACE-METALS IN THE SHORE CRAB CARCINUS-MAENAS (L)

1. The influence of starvation and copper exposure on the composition of the carapace of the shore crab, Carcinus maenas has been investigat ed. The effects of the concentrations of selected trace metals in the carapace and midgut gland have also been examined. 2. Differences in n utritional state did not affect the concentrations or relative proport ions of the principle carapace components (calcium, chitin and protein ), but starvation was associated with a reduction in carapace copper c oncentration. Copper concentration in the midgut gland increased in '' starved'' crabs, while midgut gland zinc and calcium concentrations re mained unchanged. 3. Starvation in combination with copper exposure (0 .5 mg Cu/l) resulted in alterations in both carapace composition and t race metal loads. Carapace calcium concentrations were reduced signifi cantly following copper exposure irrespective of the nutritional state of the crabs. However, the reduction was more marked in ''fed'' crabs than in ''starved'' animals. 4. Copper-exposed crabs exhibited raised carapace copper concentrations while carapace zinc concentrations wer e depressed. Such changes were most pronounced in copper-exposed ''sta rved'' crabs. 5. Calcium concentrations in the midgut glands of ''star ved'' copper-exposed animals were significantly elevated compared with those in either control or ''fed'', copper-exposed crabs. 6. The find ings are discussed with regard to their ecotoxicological significance.