Relationship between feeding-induced ventilatory activity and bioaccumulation of dissolved and algal-bound cadmium in the Asiatic clamCorbicula fluminea

The influence of feeding-induced ventilatory adaptation on cadmium accumulation patterns was analyzed in quiescent Asiatic clam Corbicula fluminea studied in steady-state conditions at 15 degrees C and 25 degrees C and in air-equilibrated water. Ventilatory activity, algae inflow rate, amounts of inspired dissolved and algae-bound Cd, and whole-body and tissue-specific metal concentrations were studied during a 15-d exposure period at a low dissolved cadmium concentration of 2 microg/L and various algal concentrations of Scenedesmus subspicatus. Great care was taken not to externally stimulate animals. Four main results were obtained as regard to regulation of ventilatory activity and metal accumulation rate. First, at 25 degrees C, feeding purposes strongly stimulated ventilatory activity, while at 15 degrees C, it was independent of it except at 1 to 2 x 10(5) algae/ml. Second, Cd accumulation rate increased at higher temperature. Third, accumulation rate exhibited a positive correlation with the ventilatory flow rate. Fourth, no correlation was observed with the quantity of ventilated algae-bound Cd but, rather, with the quantity of ventilated dissolved Cd. It is concluded that the physiology of the animals can be fundamental in affecting metal accumulation process.