Abstract

Juvenile oysters (Ostrea chilensis) from two populations (Quempille ' n estuary and Pullinque bay) were exposed to a toxic diet containing paralytic shellfish toxins (PST), produced by Alexandrium catenella, followed by a detoxification period. Feeding behaviour, toxin profile, dynamics of intoxication/detoxification, and survival were evaluated over the entire experimental period. Both populations reduced their feeding rates during the 30 -day exposure to the toxic diet. This negative effect was reversible when the diet was switched to the non-toxic one. Oysters from the estuary accumulated PST more rapidly than the population from the bay, suggesting their increased ability to cope with more adverse conditions. Both populations showed low detoxification capacity. Survival was significantly higher in oysters from the estuary, compared to those from the bay. Due to the increasing frequency and intensity of A. catenella blooms in southern Chile, it is necessary to better understand the responses of O. chilensis in different environments. This is important not only because of the ecological and commercial relevance of the bivalve, but also in consideration of expected climate change scenarios, where the new environmental conditions could favour the frequency and intensity of harmful algal bloom events.