Relationship between the occurrence of the toxic dinoflagellate Dinophysis spp. and the accumulation of diarrhetic shellfish poisoning toxins in the mussel Mytilus galloprovincialis in Ise Bay, western Japan

A comparison of diarrhetic shellfish poisoning (DSP) and other lipophilic toxin profiles between the toxic dinoflagellate Dinophysis spp. and the mussel Mytilus galloprovincialis in Ise Bay, western Japan was carried out by liquid chromatography/mass spectrometry (LC/MS). Samples of D. acuminate contained OA (0.1-3.4 pg/cell), DTX1 (0.4-4.6 pg/cell), PTX2 (2.2-69.6 pg/cell) and PTX2SA (10.8-99.5 pg/cell), and D. caudata contained PTX2 (32.6-42.9 pg/cell) and PTX2SA (99.9-156.1 pg/cell). DSP toxin levels of D. rotundata samples were very low. Although the major toxin in the plankton samples was PTX2, the mussels contained PTX2SA which is not toxic, and PTX2 was significantly lower in the mussels than in the plankton samples. The results indicate that the mussels have an ability to reduce the toxicity of PTX2 by conversion to PTX2SA. Therefore, we conclude that OA and DTX1 derived from D. acuminate are responsible for inducing toxicity in the mussels in Ise Bay.