Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 4495
Title: Heterosigma akashiwo in the Salish Sea: Defining growth and toxicity leading to fish kills
Author: W. P. Cochlan, Vera L. Trainer, C. G. Trick, M. L. Wells, B.-T. Le Eberhart, Brian D. Bill
Publication Year: 2013
Journal: Proceedings of the 15th International Conference on Harmful Algae
Keywords: harmful algal bloom,Heterosigma akashiwo,

The raphidophycean flagellate, Heterosigma akashiwo, (Y. Hada) Y. Hada ex Y. Hara et M. Chihara is responsible for extensive mortality of cultivated (pen-raised) finfish in Puget Sound, Washington, ($2-6 million in losses per episode), and may also affect wild nekton populations in the Salish Sea waters of British Columbia and Washington. Over the past two decades, these ichthyotoxic blooms have increased in both scope and magnitude, but neither the factors responsible for bloom initiation and maintenance, nor toxicity are clearly understood. The effects of cellular growth phase and the degree of nutrient sufficiency on the relative toxicity of these cultured cells were examined in a laboratory study with three different Puget Sound isolates of H. akashiwo. Toxicity, measured as decreased viability of a rainbow trout cell line (RTgill-W1) exposed to aqueous H. akashiwo extracts, was consistently elevated during the stationary phase of cell growth following the depletion of external N reserves due to phytoplankton uptake, whereas all three isolates were non toxic during their nutrient-replete, exponential phase of growth. These results are the first to demonstrate variability in toxicity as a result of physiological changes associated with growth stage or nutrient availability for cultures of H. akashiwo.


Heterosigma akashiwo growth and toxicity

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