CHANGES IN THE TISSUE CONCENTRATIONS AND CONTENTS OF CALCIUM, COPPER AND ZINC IN THE SHORE CRAB CARCINUS-MAENAS (L) (CRUSTACEA, DECAPODA) DURING THE MOLT CYCLE AND FOLLOWING COPPER EXPOSURE DURING ECDYSIS

The tissue concentrations and contents of calcium, copper and zinc wer e determined at different stages in the moult cycle of the shore crab Carcinus maenas. The crabs were dissected into the following tissues: the midgut gland, the gill, the 'rest tissue' (the latter defined as t he left over tissue, i.e. muscles and exoskeleton), and the haemolymph , and analysed as such. One group of crabs was maintained in clean sea water. In these crabs, calcium was lost front haemolymph during premou lt and apparently stored in the midgut gland. At ecdysis approximately 90% of the whole body calcium content was lost width the exuviae whil e the haemolymph calcium content doubled. During early postmoult calci um stored in the midgut gland was used in combination with calcium abs orbed from the surrounding seawater for a rapid calcification of the n ew exoskeleton. Both the copper and zinc concentrations declined Bt th e 'rest tissue' compartment during premoult. At ecdysis the haemolymph copper and zinc contents increased 35 and 86%, respectively, from pre moult to the newly moult stage. Al the same time, however, the copper and zinc haemolymph concentrations decreased During postmoult, copper (25%) and zinc (45%) were lost from haemolymph and mainly excreted but a minor fraction (5-10%) was stored in the midgut gland. A second gro up of crabs was maintained in copper-contaminated seawater (0.1 mg l(- 1) during ecdysis and postmoult. Following exposure of the animals to raised ambient levels of copper, the calcium and zinc contents of the midgut gland were reduced while the copper contents of the midgut glan d and most other tissues were increased in comparison to crabs held in clean seawater. (C) 1997 Elsevier Science Ltd.