Feeding of the tintinnid ciliate Favella taraikaensis on the toxic dinoflagellate Alexandrium tamarense and the fate of prey toxins

To establish the fate of paralytic shellfish poisoning (PSP) toxins in planktonic foodwebs, feeding activities of the planktonic ciliate Favella taraikaensis on the PSP-producing alga Alexandrium tamarense were examined in laboratory experiments and the toxin content in the ciliates was quantified by fluorometric high-performance liquid chromatography. In six experiments,F. taraikaensis actively fed on A. tamarense and grew rapidly. The maximum specific growth and ingestion rates of F. taraikaensis on a diet of A. tamarense (>300 cells ml–1) ranged from 0.7 day–1 to 1.5 day–1 and from3.1 cells individual–1 h–1 to 5.8 cells individual–1 h–1 respectively. The PSP toxin content in F. taraikaensis grown on A. tamarense was low and the individual toxin content of F. taraikaensis was lower than the cellular toxin content of A. tamarense. The PSP toxins of A. tamarense were therefore scarcely accumulated within F. taraikaensis during the feeding process.