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

Morten Bo Søndergaard Svendsen*, Nikolaj Reducha Andersen, Per Juel Hansen, John Fleng Steffensen

*Corresponding author for this work
26 Citations (Scopus)


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
Article number11
Issue number1
Publication statusPublished - 1 Jan 2018


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


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