Effects of harmful algal blooms on fish: Insights from Prymnesium parvum

Morten Thougaard Svendsen*, Nikolaj Reducha Andersen, Per Hansen, John Fleng Steffensen

*Corresponding author for this work

    Research output: Contribution to journalJournal articleResearchpeer-review

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    Blooms of the planktonic alga Prymnesium parvum pose a global threat, causing fish kills worldwide. Early studies on the exposure of fish to P. parvum indicate that toxic effects are related to gill damage. The more strictly defined concept of adverse outcome pathways has been suggested as a replacement for the mode of action in toxicology studies. In this study, rainbow trout (Onchorhyncus mykiss) were exposed to P. parvum. During exposure, oxygen consumption was determined by respirometry, and ventilation and coughing rate were determined via video surveillance. Per breath oxygen consumption was calculated to assess the ventilation effort to obtain a unit of oxygen. A second experiment monitored fish behavior to assess recovery. The results indicated that oxygen consumption initially increased, but on average fell below the standard oxygen consumption at 70% relative exposure. Being a function of ventilation frequency and oxygen consumption, the per breath oxygen consumption decreased throughout exposure. Behavioral results determined that short-term P. parvum exposure subsequently caused the exposed fish to seek flow refuge immediately and to a greater extent than unexposed fish. The adverse outcome pathway of P. parvum on rainbow trout is that P. parvum acts as a gill irritant resulting in non-recoverable respiratory failure.
    Original languageEnglish
    Issue number1
    Number of pages12
    Publication statusPublished - 2018

    Bibliographical note

    This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).


    • Harmful algal bloom
    • Prymnesium parvum
    • Onchorhyncus mykiss
    • Fish acute toxicity syndrome
    • Adverse outcome pathway
    • Gill damage
    • Oxygen consumption
    • Ventilation


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