Cadmium accumulation in the female shore crab Carcinus maenas during the moult cycle and ovarian maturation

The influence of moulting and ovarian maturation on cadmium accumulation in the tissues of female shore crabs Carcinus maenas exposed to 1 mg Cd l(-1) in the water was investigated. Cadmium accumulation in all tissues examined was markedly increased in crabs in the postmoult stages (A and B) compared to crabs in all other moult stages. During the moult cycle, average cadmium accumulation in the midgut gland ranged from 29 mug Cd g(-1) dw at premoult stage (D-2 to 589 mug Cd g(-1) dw at postmoult stage (A). Average cadmium concentrations in the haemolymph ranged from 0.56 mug Cd ml(-1) at intermoult stage (C-4) to 4.6 mug Cd ml(-1) at postmoult stage (A), while the gills accumulated from 103 mug Cd g(-1) dw in intermoult stage (C-3) to 352 mug Cd g(-1) dw in postmoult stage (A). Cadmium concentration in gills and haemolymph was also significantly higher in crabs in late premoult stage (D-3) compared to C-4-crabs, while midgut gland cadmium concentration remained elevated in C-1- and C-3-intermoult stages relative to C-4 During ovarian maturation the cadmium accumulation in midgut gland, gills, ovaries and haemolymph decreased. Average cadmium concentration in the midgut gland decreased from 63 mug g(-1) dw in ovarian Stage I to 19 mug g(-1) dw in ovarian Stage VI. The same pattern was observed for gills, haemolymph and ovaries. The present study demonstrates that cadmium accumulation in the female shore crab strongly depends on the physiological status of the animal. A possible association between physiological calcium requirements and cadmium accumulation during moulting is discussed.