Differential Retention of Okadaic Acid (OA) Group Toxins and Pectenotoxins (PTX) in the Blue Mussel, Mytilus edulis (L.), and European Flat Oyster, Ostrea edulis (L.)

ABSTRACT This paper presents the results from an experiment, where uptake and elimination of diarrhetic shellfish toxins (DST) of the okadaic acid (OA) and pectenotoxin (PTX) groups were compared between blue mussels (Mytilus edulis) and European oysters (Ostrea edulis). Caged mussels and oysters were suspended in the water column and exposed to a dense bloom of Dinophysis acuta (500–2000 cells L-1) for 4 wk, which was followed by detoxification in the laboratory during 7 wk. Weekly sampling and analysis of OA-group toxins including fatty acid esters (‘DTX-3’) as well as PTX in individual shellfish and plankton samples were performed. The results showed that mussels rapidly accumulated OA-group toxins to levels about 10 times above the regulation limit (160 µg OA kg-1 mussel) whereas concentrations never reached this limit in oysters during the field exposure. Overall, levels were 10–50 times greater in mussels. The OA-group toxins were mainly in the form of esters (>90%) in oysters, whereas in mussels, t...