AME prepress abstract  -  DOI: https://doi.org/10.3354/ame01846

Acute toxicity of the cosmopolitan bloom-forming dinoflagellate Akashiwo sanguinea to finfish, shellfish, and zooplankton

Ning Xu*, Meng Wang*, Yingzhong Tang, Qun Zhang, Shunshan Duan, Christopher J. Gobler

*Email: txuning@163.com

ABSTRACT: The unarmored dinoflagellate Akashiwo sanguinea is a well known cosmopolitan harmful alga. The toxic nature of this alga, however, has yet to be examined using multiple clonal isolates. In this study the toxicity of three clonal cultures of A. sanguinea, JX13 and JX14, isolated from Daya Bay, South China Sea, as well as AS2, isolated from Chesapeake Bay, USA, to multiple aquatic animals including species of finfish, shellfish, shrimp, and zooplankton was examined. The whole-cell cultures of A. sanguinea exhibited acute lethal effects on the shrimp Penacus vannamei, the bivalve Meretrix meretrix, and two species of fish Mugil cephalus and Mugilidae sp. with 72-h mortalities ranging from 20-100%. The sonicated and filtrated cultures were lethal to brine shrimp Artemia salina, while the filtrate of whole-cell cultures were not, suggesting toxins were intracellular. Boiling and freezing led to significant reductions in toxicity. A. sanguinea toxicity differed among the Chinese strains, and the hemolytic activity of one Chinese strain was three-fold greater than that of the American strain. Cultures in exponential phase displayed stronger toxicity and the greatest toxicity of A. sanguinea was observed at 20 °C and a salinity of 35, conditions optimal for growth of the alga. Toxicity was enhanced by increased nutrient supply, suggesting this species could both directly (via increased growth) and indirectly (e.g. via enhanced toxin production) become more toxic in response to eutrophication. Collectively, findings suggest that the ability to produce and release toxin(s) may promote A. sanguinea blooms by suppressing predators and competitors.