High toxicity of the novel bloom-forming species Chattonella ovata (Raphidophyceae) to cultured fish

Feeding by raphidophytes on the cyanobacterium Synechococcus sp.

“…Clough & Strom 2005) and fish (e.g. Hiroishi et al 2005) and have often caused large-scale fish mortality rates in the ABSTRACT: We investigated feeding by the raphidophytes Chattonella ovata, C. subsalsa, Fibrocapsa japonica, and Heterosigma akashiwo on the cyanobacterium Synechococcus sp. To explore whether each species is able to feed on Synechococcus sp., we carefully observed inside target grazer cells using an epifluorescence microscope and tranbsmission electron microscope (TEM).…”

Evaluation of the potential biological toxicities of aqueous extracts from red tide phytoplankton cultures in in vitro and in vivo systems

“…In addition, ROS are supposed to be involved in ichthyotoxic mechanisms (Yang et al, 1995;Hiroishi et al, 2005), and the radical scavenging substance produced by red tide flagellates could be a novel agent for the remedy of flagellate-mediated ichthyotoxicity. The relatively nontoxic properties and heat-resistance of the extract from G. impudicum could be particularly desirable characteristics for a commercial agent.…”

“…might be one of the causative factors responsible for the toxic effects. For example, ROS generated by C. ovata exhibited toxic effects on cultured fish under laboratory conditions (Hiroishi et al, 2005), and Heterosigma akashiwo, which also belongs to the raphydophycean flagellates, has been reported to have a ROS-mediated toxic effect on rainbow trout (Yang et al, 1995). In addition, it has been found that C. marina, H. akashiwo, and C. ovata, all of which belong to the raphydophycean flagellates, produce potent radical scavengers against superoxide anions (Kim et al, 2000;Sato et al, 2007).…”

Some Dinophycean Red Tide Plankton Species Generate a Superoxide Scavenging Substance

“…may be one of the causative factors in the toxic effects. Indeed, ROS generated by C. ovata exhibited toxic effects on cultured fish under laboratory conditions, 19) and Heterosigma akashiwo, which also belongs to the raphidophycean flagellates, has been reported to have an ROS-mediated toxic effect on rainbow trout. 20) The fundamental mechanism by which superoxide is generated by Chattonella spp.…”

“…Since the ability to scavenge superoxide is supposed to function as a self-defense mechanism against superoxide generated by the flagellates themselves, we expect that the substances responsible for superoxide scavenging are a novel antioxidant agent that can be made available for neutralceuticals, cosmeceuticals, and veterinary products. In addition, superoxide is thought to be a ichthyotoxic substance, 19,20) and the substances produced by red tide flagellates might be a novel agent for the remedy of ichthyotoxicity induced by the flagellates themselves. Hence, we screened for antioxidant substances generated by wide variety of red tide flagellates.…”