Environment Canada Scientists Study St. Lawrence Cyanobacteria

Found throughout the world, cyanobacteria have been around for the last 3 billion years, sometimes in extreme environmental conditions. Although they are microscopic, once they bond together, they form algae that are easily visible to the naked eye. The proliferation of toxic algae in Canada and around the world is a growing problem whose effects are not yet well understood.

In 2005, Lake Saint-Pierre and Lake Saint-Louis were not immune from cyanobacteria. Environment Canada scientists observed the presence of cyanobacteria covering an area of over 25 km² in these fluvial lakes of the St. Lawrence in Quebec. These cyanobacteria (Lyngbya wollei) form a black mat of threads on the bottom of the river and demonstrate the need to assess the cumulative effects of nutrient enrichment of St. Lawrence waters by agricultural streams and urban effluent.



Lake Saint-Pierre
Photo: Michel Arseneau, Environment Canada

To understand the factors that lead to the development of cyanobacteria and the effects of these organisms on the ecosystem, a team of Environment Canada scientists led by Yves de Lafontaine was formed as part of the Fluvial Ecosystem Research Section, a component of the Water Science and Technology Directorate. The team members are Christiane Hudon (ecology), Christian Gagnon (chemistry), François Gagné (ecotoxicology) and André Lajeunesse (chemistry).

The work of this research group, conducted in collaboration with provincial departments and the university community, will make it possible to identify and measure the toxins produced by cyanobacteria, as well as their persistence, in order to better understand their effects on the ecosystem. “The proliferation of mats of Lyngbya wollei coincides with the disappearance of aquatic plants, which are the habitat and food source of numerous St. Lawrence invertebrate and fish species,” states Christiane Hudon.

On other fronts, research work in this field will further the understanding of ecotoxicity on aquatic wildlife through the use of effect biomarkers. “Biomarkers act like blood tests, in which various parameters are measured to characterize the state of an organism’s health and to confirm an ecotoxicological problem arising from the presence of cyanobacteria in the environment,” specifies François Gagné.

He concludes, “We are also trying to identify aquatic sentinel species, or species that are sensitive to cyanobacteria. These sentinels are like scouts that alert us to toxic effects in aquatic wildlife.”

The results will, depending on environmental conditions, identify the causes of the proliferation of cyanobacteria, in order to monitor its distribution, its abundance and toxin levels so that the cumulative effects in interaction with other contaminants may be anticipated.