New cyanotoxins discovered in the Yamaska River and Lake Saint-Pierre

2024-08-16 Updated: 2024-09-09

Photo: Environment and Climate Change Canada

Cyanobacteria, also known as blue-green algae, are microscopic organisms found in both fresh water and salt water. There are various types of cyanobacteria, some of which are capable of producing harmful toxins known as cyanotoxins. As a result of human activity and climate change, cyanobacteria are expanding rapidly, and with potential consequences for the health of humans and any living organism exposed to them.

Although a wide variety of cyanotoxins exist, the most studied are the microcystins, which are monitored through quality thresholds for drinking and recreational waters due to their harmful effects on human health. With technological advances in analytical chemistry, unknown toxins are continually being identified and measured in affected environments. The health consequences of these toxins range from liver disorders and, in some cases of acute or chronic exposure, the development of tumors.

St. Lawrence Action Plan (SLAP) scientists are studying these toxins to better understand their impacts on the environment and human health, improve predictive models for cyanobacteria and cyanotoxin production, and better target changes in agricultural practices and wastewater management that can help reduce their proliferation.

Why choose the Yamaska and Lac Saint-Pierre areas for this study?

The presence of heavy agricultural activity and the phenomenon of eutrophication (the advanced decay of waterways caused by excess nutrients) provide favorable conditions for observing cyanotoxins. Studies already initiated in the past in the Yamaska and Lake Saint-Pierre sectors have motivated SLAP scientists to continue their research to learn more about cyanotoxins. In addition, several SLAP scientific teams are working in these watersheds on projects related to the impacts of pesticides and nutrients caused by agricultural activities, thus promoting the sharing of information and data between experts.
 

What are the scientific findings of this research?

• The presence of four new microcystins and anabaenopeptins in the Lac Saint-Pierre area

By collecting and analyzing surface water samples, St. Lawrence Action Plan scientists were able to identify the presence of four new microcystins and anabaenopeptins in the Lac Saint-Pierre area (see article: A Data-Independent Methodology for the Structural Characterization of Microcystins and Anabaenopeptins Leading to the Identification of Four New Congeners). A fast and efficient new technique called high-resolution mass spectrometry was used to identify a wide range of compounds produced by cyanobacteria.

• A new family of dominant cyanotoxins observed north of the Yamaska River: anabaenopeptins

Similar to microcystins, anabaenopeptins are a dominant family of cyanotoxins observed in the summer of 2022-2023 north of the Yamaska River. This is a major discovery for the SLAP team, as this type of cyanotoxin had never been observed before. It also gives us a better understanding of cyanotoxin diversity, furthering our knowledge on the subject.  

Conversely, during field visits in July 2023, no anabaenopeptins were identified at the mouth of Lac Saint-Pierre, but microcystins did appear for the first time. The variety of cyanotoxins observed varies from one area to another.

In pursuit of this research, SLAP scientists will seek to understand the diversity of cyanotoxins, provide more comprehensive and accurate monitoring of water bodies, and identify associated health risks. The results of this research will also help authorities to make informed decisions in the fight against these cyanotoxins, which are increasingly present in our environment.