Inter- and intra-population variability in behavioral and physiological responses of the softshell clam, Mya arenaria, to the PSP toxin-producing dinoflagellate, Alexandrium tamarense

Paralytic shellfish poisoning (PSP) poses a severe human health risk and causes closures of shellfisheries worldwide. The goal of this study was to investigate the intraspecific variation among and within populations of Mya arenaria in their sensitivity to PSP toxins and thus their capacity to accumulate these toxins. Previous studies have shown that bivalve species vary greatly in their response to toxin exposure, but very few have investigated variability within a species. This study determines the magnitude and consequences of intrinsic variation in toxin susceptibility in M. arenaria, which has important implications for the prediction of shellfish toxicity and management of fisheries in PSP-affected regions. Two populations of clams with contrasting histories of toxin exposure were compared in terms of their burrowing behavior and physiological responses: feeding and oxygen consumption rates, toxin uptake kinetics, as well as survival during 2–3 weeks of exposure. Clams were exposed to bloom levels of a highly toxic strain of Alexandrium tamarensis (PR18b; 60–100 pg STXeq cell−1). Feeding, toxin accumulation and survival were also compared among phenotypes (resistant/sensitive) from the two populations. (Abstract shortened by UMI.)...