Strain-dependent lethal effects on abalone and haemolytic activities of the dinoflagellate Karenia mikimotoi

摘要

One of the clonal strains of Karenia mikimotoi NGU04 isolated from Kyushu Island in Japan, showed the most potent fish-killing activity in preliminary experiments. To evaluate shellfish toxicity, two species of juvenile abalone were exposed to the NGU04, and the toxicities were compared with those of two other K. mikimotoi strains. Of the two abalone species tested, N. gigantea showed a higher sensitivity to NGU04 than the hybrid abalone (N. discus hannai male x N. gigantea female) did. In comparative studies using N. gigantea, the NGU04 exhibited stronger toxicity on abalone than other strains. The cell-free culture supernatant and the ruptured cell suspension of the NGU04 showed no significant lethal effects on N. gigantea. The NGU04 showed a stronger haemolytic activity on rabbit erythrocytes than did the other two strains. Furthermore, the haemolytic activities of the NGU04 strain towards erythrocytes of four fish species were also stronger than those of other strains.