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Algal bloom toxicity harming fish year round, U of G study finds


Cyanobacterial toxins can harm fish populations even in the early stages of algal bloom development when humans cannot see it, not just during the peak of summer, new research from the University of Guelph has found.

“The data suggests we need to be tracking these blooms as early as spring,” announced post-doctoral researcher Dr. René  Sahba Shahmohamadloo from the University of Guelph’s Department of Integrative Biology.

Shahmohamadloo led the study along with researchers from the Ontario Ministry of the Environment, Conservation and Parks. The work was recently published in Environmental Science & Technology. 

The research team examined the negative impacts of algal blooms before the release of cyanotoxins — microcystins in particular — which are the most common toxin released by blooms.

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Adult and juvenile rainbow trout were exposed to two types of microcystin toxicity, intracellular and extracellular. Within 24 hours after exposure, the fish had buildups of the toxin in most tissues, with greater accumulation in the extracellular state, the study says. Within 96 hours, adverse health effects were measurable in all tissues and cancer-causing proteins were detected.

“We saw at the cellular level that cyanotoxins are causing these adverse health effects in fish,” said Shahmohamadloo in a statement from the University of Guelph. “The implications for that are substantial for governmental and non-governmental regulatory agencies that are trying to protect the public and also fisheries,” he added.

The toxicity exposure may not kill fish, the research team found, but noted that the health effects may be long-lasting.


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