Haemolytic activity and reactive oxygen species production of four harmful algal bloom species

Based on haemolytic activity and reactive oxygen species (ROS) production of Chattonella marina, Chattonella antiqua, Heterocapsa circularisquama, Alexandrium tamiyavanichii and Karenia mikimotoi, the species were categorized into four types. (1) H. circularisquama: haemolytic activity was detected in both cell suspension and cell-free culture supernatant, but with greater activity in cell suspension than in the supernatant suggesting the presence of both cell surface and secreted haemolytic agents. (2) A. tamiyavanichii: equal haemolytic activities were detected in both the cell suspension and cell-free culture supernatant suggesting the presence of only secreted haemolytic agents. (3) K. mikimotoi: haemolytic activity was detected only in the cell suspension, indicating haemolytic agents occur only on the cell surface. (4) C. marina and C. antiqua: no significant haemolytic activity was detected in either cell suspension or cell-free culture supernatant, but high ROS were detected in the cell suspensions. Heterocapsa circularisquama and K. mikimotoi showed lethal effects on rotifers (Brachionus plicatilis), whereas A. tamiyavanichii, C. marina and C. antiqua had no effect. Our results suggest that H. circularisquama, K. mikimotoi and A. tamiyavanichii produce haemolytic agents with distinct characteristics, whereas C. marina and C. antiqua have an extremely potent ability to produce ROS.