Effect of copper on survival, osmoregulation, and gill structures of freshwater prawn (Macrobrachium rosenbergii, de Man) at different development stages

This study evaluated the acute toxicity of copper at different life stages of freshwater prawn, Macrobrachium rosenbergii, to determine the effect of sublethal copper concentration on osmoregulatory capacity (OC), to measure the copper level in gills, and to investigate the effect of copper on the histological change of the gills of adult prawns. The 24-, 48-, and 96-h medium lethal concentration (LC50) of copper on M. rosenbergii increased progressively along with the increasing life stage, from postlarvae, juvenile to adult. The 24-, 48-, and 96-h LC50 values for copper were higher at 0 ppt than those at 12 ppt for both juvenile and adult. After 7 d exposure to 0.75 mg Cu L 1 at 0 and 12 ppt, the OC values of exposed prawns were reduced by 12 and 47%, respectively, compared with control animals. However, the OC value of prawns exposed to 0.5 mg Cu L 1 was not significantly different from the OC value of control prawns both at 0 and at 12 ppt. The copper concentrations on gill tissues increased significantly in prawns exposed to copper both at 0 and at 12 ppt. After the copper exposure, swelling of lamellae, multiple hyperplasia and necrosis were observed in gill lamellae, resulting in abnormal gill tips. An obvious relation between the impairment of osmoregulation and the structural damage of gills are reported in this study