Growth of tissues related to haemolymph copper throughout the moult cycle of the lobster Homarus gammarus

The relationship between tissue weights and haemolymph copper levels in field-collected European lobsters Homarus gammarus was investigated to assess whether haemolymph copper concentration can be used to reliably determine nutritional condition in lobsters. During the moult cycle, the soft tissue weight (mostly muscle) increased concomitantly with a decrease in haemolymph weight while exoskeleton weight increased from postmoult to intermoult. Haemolymph copper concentration gradually increased from postmoult to premoult with a range of 29.7 (Stage B) to 163.5 mu g/g wet weight (ww) (Stage D sub(0)). Our measurements suggest that the main processes that increase haemolymph copper concentration is a reduction in haemolymph space and an increase in haemolymph copper content, indicating synthesis of new haemocyanin for the oxygen supply of growing tissues. During the moult cycle, haemolymph copper content was proportional to soft tissue mass and amounted to 43.6 mu g Cu/g of soft-tissue ww (95% confidence limits = 35.5 and 51.6 mu g/g). Models for estimating soft-tissue and haemolymph wet weights from the haemolymph copper concentration and moult stage are presented. The use of haemolymph copper concentration as an index of nutritional condition reflecting tissue growth and food quantity and quality is validated.