Effect of cadmium on survival, osmoregulation and gill structure of the Sunda prawn, Macrobrachium sintangense (de Man), at different salinities

The prawn Macrobrachium sintangense is likely to be subjected to occasional exposure to combined metal and saline stressors in its natural environment. This research evaluated the acute toxicity (96 h LC₅₀) of cadmium (Cd) on the prawn M. sintangense, with respect to the osmoregulatory capacity (OC) of prawns and to document histological changes in the gills after exposure to sublethal Cd concentrations at different salinities. The 96 h LC₅₀ of Cd to M. sintangense decreased with increasing salinity. The 96 h LC₅₀ values were 89.12 (72.53–109.50), 681.26 (554.20–837.46) and 825.37 (676.99–1006.27) μg CdL⁻¹ at 0, 10 and 20 ppt, respectively. The OC of prawns exposed to 30 μg CdL⁻¹ at 0 ppt and to 300 μg CdL⁻¹ at10 ppt decreased significantly compared with that of control prawns exposed to 0 and 10 ppt respectively. Swelling, hyperplasia and necrosis of gill lamellae resulting in the loss of marginal canals were observed in the gills of prawns exposed to 30 μg CdL⁻¹ at 0 ppt and to 300 μg CdL⁻¹ at 10 ppt for 7 days.