The Gleaner

Invasive aquatic plant discovered in Lake Saint-François

Saint-Chrysostome-based conservation group Ambioterra has discovered the first recorded observation in Quebec of an invasive exotic aquatic plant on the south shore of Lake Saint-François in Dundee.

The plant is a type of freshwater macroalgae called Nitellopsis obtusa, or more commonly, starry stonewort. Native to Europe and Asia, it can reach lengths of over 1.5 metres, is bright translucent green, and has irregular branches that grow in whorls from the main stem. A distinguishing feature of this species is the presence of whitish, star-shaped bulbils measuring around four millimetres.

The presence of the plant was discovered with the help of a landowner participating in Ambioterra’s project combatting invasive exotic species between Lake Saint-François and Lake Saint-Louis. The project, now in its second phase, is funded in part by the St. Lawrence Marine Biodiversity Program, which is sponsored by the St. Lawrence Action Fund (SLAF) to promote ecosystem and biodiversity conservation in the St. Lawrence River and its Gulf. To carry out its project, Ambioterra has received $61,600 in SLAF funding, as well as additional support from the Montreal-based Echo Foundation, and the Quebec government’s Advantage St. Lawrence vision and action plan.


Ambioterra has recorded the first observation in Quebec of the invasive species Nitellopsis obtusa in Lake Saint François near Dundee PHOTO Courtesy of Ambioterra


“Lake Saint-François is the first gateway for exotic invasive aquatic species from the Great Lakes and the Ontario section of the St. Lawrence River,” says Ambioterra president Karel Ménard, who is advising shoreline residents and lake users to be vigilant when it comes to this species. Nitellopsis obtusa is known to invade lakes and rivers where it can outcompete native vegetation to form stands that reduce fish spawning habitat.

The presence of the invasive algae has been confirmed by botanists sent by the Ministère de l’Environnement et de la Lutte contre les changements climatiques, de la Faune et des Parcs (MELCCFP). Its discovery has now been recorded on their exotic invasive species detection tool, Sentinelle.

Ambioterra secretary Gaétan Fortier says it is now even more important that boat owners apply basic clean-up procedures to reduce the spread of this invasive aquatic species. (SR)

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