Toxin content and toxic effects of the dinoflagellate Gyrodinium corsicum (Paulmier) on the ingestion and survival rates of the copepods Acartia grani and Euterpina acutifrons

Short-term experiments showed that ingestion rates of the copepods Acartia grani and Euterpina acutifrons on different concentrations of the dinoflagellate Gyrodinium corsicum were not usually different from those obtained with the non-toxic and similar sized Prorocentrum triestinum. Long-term experiments showed that no A. grani survived for more than 288 h on concentrated cultures (1500 μg C l−1) of G. corsicum compared with survival rates of 86.7% on the non-toxic P. triestinum. In contrast high and similar survival rates were found for E. acutifrons exposed for the same time to similar concentrations of both dinoflagellates. These results demonstrated that G. corsicum produce toxins which have significant adverse effects on the long-term survival rates of some copepods like A. grani but not on other copepods like E. acutifrons. The possibility of PSP-toxin production by G. corsicum was analysed by chromatographic analysis (HPLC-FD) and mouse bioassay of extracts obtained from cultures maintained in exponential growth phase in f/2-Si and L1 culture mediums. These analyses and the bioassay ruled out the presence of PSP toxins in this dinoflagellate. However, mouse tests provided the first evidence for the presence of some type of NSP toxin in G. corsicum. Haemolytic assays also gave the first positive results for the methanol extract of this dinoflagellate species.