Molecular and physiological responses in shore crabs Carcinus maenas following exposure to copper

The effects of acute (24 h) and chronic (four weeks) copper exposure and subsequent recovery in ‘clean’ conditions on cardiac activity were examined in shore crabs (Carcinus maenas). Cardiac activity was monitored by Automated Interpulse Duration Assessment (AIDA) which enables detection of irregularities in cardiac rhythms in selected invertebrates. Mean interpulse durations, maximum interpulse durations and coefficients of variation were significantly affected by exposure to copper for 24 h and four weeks (p < 0.05). Recovery of normal cardiac activity was evident following a six week recovery period in ‘clean’ conditions. However, high levels of mortality were seen among crabs exposed to the two highest copper concentrations (0.6 and 0.8 mgl−1 Cu).The extent of recovery was assessed by subjecting the surviving crabs to a physiological challenge. There were no apparent differences in circulatory response to physiological challenge between crabs previously exposed to copper and control crabs (p > 0.05). Gill copper concentrations were significantly elevated in crabs that had previously been exposed to copper, despite their return to ‘clean’ seawater for six weeks (p < 0.01). Midgut gland wet weight/dry weight (WW/DW) ratios, haemolymph total protein and midgut gland metallothionein concentrations did not reflect the previous copper exposure. The findings of the present study indicate that AIDA may be a valuable tool for use in toxicity testing