• Journal of Life Science
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• v.14 no.4
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• pp.589-592
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• 2004

The growth response of the fish-killing dinoflagellate Cochlodinium polykrikoides was studied in cultures, using the treatment of Ceratium extracts by a methanol, a water-soluble, and a cell-free medium. The cell-free medium had the most increasing on the growth of C. polykrikoides cultures, enriched with $\geq$ 25% Ceratium, whereas the methanol and water-souble fractions did not affect the growth of C. polykrikoides exposed to even higher concentration. In particular, the cell-free medium also increased the growth of Gyrodinium impudicum and Chaetoceros sp., similar species to C. polykrikoides. In contrast to C. polykrikoides, G. impudicum and Chaetoceros sp., the growth of Alexandrium tamarense was inhibited significantly, and there was no great effect on the growth of Prorocentrum minimum. These results imply that Ceratium extracts may play an important role in the stimulatory effect of C. polykrikoides, and they have to affect the interaction between C. polykrikoides and Ceratium when co-existing.