The effects of trace metals on the apparent water permeability of the shore crab Carcinus maenas (L.) and the brown shrimp Crangon crangon (L.)

The effects of trace metals on the apparent water permeability (AWP) of two decapod crustaceans Carcinus maenas and Crangon crangon, were investigated. One hour exposure to 1 mg l−1 dissolved Hg or Pb significantly decreased the AWP of the shore crab, C. maenas. A similar, but not significant, tendency was observed following exposure to Cd, Cu and Zn, whereas Co had little effect. The AWP of C. maenas exposed to Cd decreased with increasing Cd concentration (0.5, 1, 4 or 8 mg l−1). This decrease was independent of exposure time (1, 5 or 10 days). The influence of Zn (500 μg l−1) on the apparent water permeability of the brown shrimp C. crangon was also investigated. After 24 h exposure to Zn, AWP decreased significantly. This reduction persisted for at least 3 days. After 6 days of exposure, AWP returned to the initial level. Whether trace metal induced changes in the AWP are the result of toxic effects of the metals or represent physiological adaptations minimizing the effects of external perturbations is discussed.