Resuspended hypnozygotes of Alexandrium fundyense associated with winter occurrence of PSP in inshore Newfoundland waters

Abundance of sediment resting cysts, or hypnozygotes, of the toxic dinoflagellate, Alexandrium fundyense, in the stomachs of blue mussels, Mytilus edulis, was found to be positively correlated with the level of paralytic shellfish poisoning (PSP) toxins in the mussel flesh during winter in northeastern Newfoundland. In addition, historical maximum levels of mussel toxicity were positively correlated with abundance of cysts in sediments at collection sites around the coast of the island. Several adjacent mussel culture sites were examined to determine the physical mechanisms involved in initiation and maintenance of high levels of mussel intoxication at some sites while others remained clear. We found that cultures located over depositional basins in embayments which had shallow sills and were oriented along the fetch of strong winds had persistently high toxin levels. Cultures located over erosional bottoms in open basins remained free of high levels of PSP toxins. We propose that taking this mechanism for winter intoxication into account when selecting growing sites will greatly benefit the Newfoundland mussel culture industry.