Effects of short-term exposure to paralytic shellfish toxins on clearance rates and toxin uptake in five species of New Zealand bivalve

Algal blooms produced by toxic dinoflagellates have increased worldwide, resulting in economic losses to aquaculture and fisheries. Bivalve species differ in their ability to feed on toxin-producing dinoflagellates and this could result in differences in toxin accumulation among species. In New Zealand, the effects of paralytic shellfish poisoning (PSP) toxins on the physiology of bivalve molluscs are relatively unknown. We hypothesised that the feeding responses of five New Zealand bivalve species exposed to PSP-toxic dinoflagellates would be species-specific, affecting their accumulation of toxins. Each species was exposed to toxic and non-toxic species of Alexandrium spp. and clearance rate used as an index of sensitivity to PSP toxins. Clearance rates for the mussel Perna canaliculus and the clam Dosinia anus were unaffected by the presence of toxic dinoflagellates, whereas the rate in the scallop Pecten novaezelandiae decreased significantly. There were variable results for the clam Paphies donacina and the oyster Ostrea chilensis. Species-specific biotransformation of PSP-toxins had taken place in the bivalve tissues. We conclude that the rate of accumulation of PSP toxins in the tissues of the bivalve species was influenced by their feeding behaviour and the different chemical processes that had taken place in their tissues.