Evolution of zebra mussels in Lake Memphremagog

The first report of zebra m mussels in Lake Memphremagog was made by an employee of the City of Magog in 2017. A single zebra mussel was found in July of that year between the west beach and the MacPherson wharf on a rocky substrate during an operation to remove snails as a as a swimmer's itch prevention measure. In 2018, two more zebra mussel sightings were reported by the City of Magog. On July 19 and 20 of that year, the MCI patrol, accompanied by Isabelle Picard, a biologist specializing in aquatic fauna, carried out an inventory of zebra mussels in Magog, after a report of unusual mussels observed by Mr. Denis Mongeau, owner of Plongée Magog. On July 23rd, MCI issued a report and held a press conference, showing that well established colonies were found in the lake.

Invisible to the naked eye at the larval stage and as small as 2 to 3 centimetres at maturity, the zebra mussel (Dreissena polymorpha) is an «engineer» species, which means that it modifies the natural processes of the ecosystem into which it is introduced. It has the potential to filter up to one litre of water a day in order to feed. As a result, native species may become poorly adapted to their own transformed environment. The various impacts of its powerful filtering action do not leave other species indifferent. It alters food chains and competes directly with native freshwater mussels. The economic and social repercussions can be numerous: it causes problems such as the obstruction of submerged structures like water intakes, damages pleasure craft, can cause injuries to swimmers with its sharp edged shell and is a transmission vector for avian botulism, a disease responsible for the death of thousands of aquatic birds, to name only a few...

Boaters must to redouble their efforts to limit the spread of this tiny mussel, invisible to the naked eye at the larval stage. It is more important than ever to Clean, Drain and Dry all boats travelling from one lake to another to prevent the propagation of new exotic invasive species in Lake Memphremagog and other bodies of water in the province.

The distribution of zebra mussels in Lake Memphremagogo in the summers of 2019 and 2019 is shown on the map below. In 2020, the patrol will continue its monitoring and control activities in collaboration with the Memphremagog MRC, the City of Magog and the provincial forest, wildlife and parks ministry (MFFP). Artificial substrates will be installed to aid in the monitoring of the mussel's spread and manual removal of zebra mussels will be organized with the help of volunteers.

Consult the report (in French only) verifying the presence of zebra mussels in Magog bay, and the first assesment of the situation (MCI, 2018). 

View the video on exotic invasive species.