Disruption of circulatory and respiratory activity in shore crabs (Carcinus maenas (L)) exposed to heavy metal pollution

Cardiac and respiratory activity of the shore crab, Carcinus maenas (L.), were disrupted following exposure to heavy metal ions. Exposure to 3 mg l-1 copper ions induced continuous, uninterrupted heart beat in quiescent, undisturbed crabs. Copper ions (10 mg l-1) suppressed cardiac activity and oxygen consumption within 2 hr. Alternating periods of bradycardia and tachycardia were observed together with marked changes in impedance cardiograph trace height. Similar, but more pronounced changes were seen following exposure to 1 mg l-1 mercury ions. Median perfusion index was 100 ml blood ml O2(-1) (range 58-114 ml blood ml O2(-1)) prior to pollution, but increased to peak values within the range 90-220 ml O2(-1) following exposure to copper or mercury. The effects of exposure to copper were transient and largely reversible. Exposure to mercury resulted in 100% mortality 24-48 hr after initial contamination. Death was apparently associated with loss of the osmoregulatory ability of these crabs.