Ichthyotoxicity of Chattonella marina (Raphidophyceae) to damselfish (Acanthochromis polycanthus): the synergistic role of reactive oxygen species and free fatty acids

Feeding by raphidophytes on the cyanobacterium Synechococcus sp.

“…Gill tissue damage is known to be the ultimate cause of fish death (Edvardsen & Imai 2006). Reactive oxygen species, neurotoxins, and mucus have been suggested to be responsible for the gill tissue damage (Oda et al 1997, Marshall et al 2003, Bowers et al 2006). However, Chattonella spp., F. japonica, and Heterosigma spp.…”

Significance of Antioxidative Functions of Eicosapentaenoic and Docosahexaenoic Acids in Marine Microorganisms

“…This stress was relieved by EPA. Although no other direct data supporting the antioxidative shielding effects of EPA against endogenous ROS were obtained, the speculation described above can be supported by the fact that marine raphidophycean flagellates (Chattonella) that produce high levels of ROS to kill fish are EPA-accumulating microalgae (26) and that high levels of ROS are not toxic to ROS-producing cells. External stimuli (environmental stresses) also induce the generation of various ROS in organisms (30, 46, 49).…”

“…Hence, marine organisms must be exposed to exogenous ROS including H 2 O 2 . In addition, some phytoplanktons (microalgae), such as dinoflagellates, produce high levels of ROS, such as superoxide anions, hydroxyl radicals, and H 2 O 2 under normal physiological conditions, and these are involved in killing fish and other organisms exposed to them (26,51). Since marine organisms cannot avoid these challenges by biotic and abiotic ROS, the membrane-shielding effects of n-3 LC-PUFAs likely operate as a primary protective "breakwater" for all marine microorganisms possessing them.…”

Effects of Heterosigma akashiwo (Raphidophyceae) on protist grazers: laboratory experiments with ciliates and heterotrophic dinoflagellates

“…Production of brevetoxin-like neurotoxins has been reported for several strains (Khan et al 1997, Ono et al 2000, Haque & Onoue 2002, and there is evidence that an association with bacteria is required for toxicity (CarrasqueroVerde 1999). Recently Twiner et al (2004) investigated the effect of H. akashiwo-derived extracellular organics on cell metabolism, while Marshall et al (2003) demonstrated a synergism between ROS and free fatty acids in the ichthyotoxicity of the closely related Chattonella marina. In addition to ichthyotoxicity, H. akashiwo is thought to have allelopathic effects on certain other phytoplankton species (Pratt 1966).…”