Submitted to: Journal of Fish Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/1/2003
Publication Date: 2/1/2004
Citation: Zimba, P.V., Rowan, M., Triemer, R. 2004. Identification of Euglenoid Algae That Produce Ichtyotoxins. Journal of Fish Diseases. 27:115-117. Interpretive Summary: Fish mortalities in aquaculture systems occur for many reasons. In this case, we documented the formation of algal toxins by an algal division (Euglonophyceae) previously not known to produce these compounds. Single cell isolates of this alga were used in the laboratory to reproduce fish mortalities. A culture strain of the alga was also tested on laboratory-reared fish and caused fish mortalities. We conclude that toxin production does occur in freshwater eucaryotic algae and these events can cause fish mortalities in ponds.
Technical Abstract: We report toxin production by eucaryotic microalgae in freshwater by members of the genus Euglena. Fish mortalities (sheepshead minnows, catfish, striped bass, and tilapia) have been observed using field samples as well as unialgal isolates of two species of Euglena (E. sanguinea and E. granulata). Three toxic fractions have been isolated from unialgal isolates of both species, and include both water soluble and lipophilic compounds having ichthyotoxic activity. The toxins are stable at -80 degrees Celsius for at least 60 days and are heat stable to 30 degrees Celsius.