WATERBORNE COPPER CAUSES GILL DAMAGE AND HEMOLYMPH HYPOXIA IN THE SHORE CRAB CARCINUS-MAENAS

The ultrastructure of gill lamellae was studied in shore crabs, Carcinus maenas, exposed to sublethal (0.5 mg . L-1) and lethal (2 mg . L-1) concentrations of waterborne copper for various durations. Oxygen tension, pH, and lactate concentration in arterial blood were determined in parallel studies. Extensive structural alterations involving cellular hyperplasia, vacuolization, and necrosis were found after 5-6 days of exposure to both sublethal and lethal copper levels. This led to considerable thickening of the gill epithelium and reduction of haemolymph spaces, resulting in restriction of respiratory gas exchange as shown by a marked hypoxemia. Ensuing lactacidemia suggests that tissue hypoxia was probably the major effect of the toxicant at lethal levels. In sublethal conditions, partial repair of gill tissue and recovery of normal blood oxygenation and pH were observed after 18 days of exposure.