Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 8344
Title: The regulation of toxicity in laboratory cultures of Heterosigma akashiwo from Puget Sound, Washington
Author: C. E. Ikeda, W. P. Cochlan, C. M. Bronicheski, J. R. Matheson, Vera L. Trainer, C. G. Trick
Publication Year: 2015
Journal: Proceedings of the 16th International Conference on Harmful Algae
Keywords: harmful algal bloom,Heterosigma akashiwo,toxicity,fish kill
Abstract:

Extensive finfish mortalities due to blooms of the raphidophycean flagellate Heterosigma akashiwo, (Y. Hada) Y. Hada ex Y. Hara et M. Chihara is problematic for many commercial aquaculture operations located in Puget Sound, Washington, USA. Decreased salinity has been linked to both bloom formation and toxicity for this raphidophyte, however it is unknown if toxicity increases at salinities below 20, or if there is a combinatorial effect with temperature. Using a non-axenic strain of H. akashiwo isolated from Puget Sound, cultures were exposed to a combination of three salinity (32, 20 and 10) and five temperature (14.7, 18.4. 21.4, 24.4 and 27.8ºC) conditions. Our results indicate that the toxicity of unialgal cultures of H. akashiwo increased as salinity decreased from 32 to 10. Furthermore, at salinities of 20 and 10, neither temperature nor specific growth rate were correlated with ichthyotoxicity. However at the salinity of 32, both temperature and specific growth rate were inversely proportional to toxicity, which is likely due to the effect of contamination by an unidentified species of Skeletonema in those cultures. Competition with the Skeletonema sp. resulted in an ichthyotoxic response from H. akashiwo that was greater than the stress caused by salinity alone.

Theme: Sustainable, safe and secure seafood for healthy populations and vibrant communities
Foci: Provide scientific support to ensure safe seafood for healthy populations and characterize how human activities and climate affect risks from pathogens, chemical contaminants and biotoxins