Accumulation and depuration kinetics of paralytic shellfish toxins in the scallop Patinopecten yessoensis fed Alexandrium tamarense

Adult scallops, Patinopecten yessoensis, held for 8 d separately in tanks a nd fed known amounts of cultured cells of the dinoflagellate Alexandrium ta marense were held without feeding for an additional 10 d. During the 18 d s tudy, 3 scallops were removed every 2 d and the quantity of of each toxin p resent was analyzed individually, The toxins released into the environmenta l seawater were recovered and also analyzed. These experiments showed that the individual variation in bivalve toxicity often observed in feeding expe riments and field surveys is due to differences in the amounts of dinoflage llate cells ingested by the bivalves and that a portion of the total amount of toxins accumulated in the scallop is released into the environmental wa ter. However, the sum of the amount of toxins in the scallop and that relea sed into the water cannot be explained in terms of the amount supplied by A . tamarense, suggesting that in addition to toxin accumulation from the foo d chain, another unknown mechanism is involved in toxin accumulation in the scallop. The toxins incorporated into the scallop from A. tamarense are co nsidered to undergo metabolism in the scallop through which the toxins are changed to derivatives undetectable by HPLC.