The Manitoba Great Lakes (MBGL) program is led by researchers at the Centre for Earth Observation Science (CEOS) at the University of Manitoba, and is a multi-disciplinary collaboration dedicated to conducting research and providing data for science-based decision making in the Hudson Bay Watershed.
The upper Manitoba Great Lakes (Lake Manitoba, Winnipegosis and Waterhen) include the 27th (Winnipegosis) and 32nd (Manitoba) largest lakes in the world. They are important drinking water sources for the people who live near their shores, and important recreational and fisheries resources for the region and the Province as a whole. Moreover, they help to protect Lake Winnipeg by filtering nutrients and contaminants in runoff from its western watershed. In particular, the operation of the Portage Diversion during flood events has effectively shifted significant fractions of the Assiniboine River nutrient and contaminant load from the south basin of Lake Winnipeg to the south basin of Lake Manitoba, with undocumented impacts on the latter.
Currently, the physical, chemical, biological and geological processes in the lakes are not well understood. Therefore, we have a poor ability to predict responses to change in factors such as climate, fishing pressure, and nutrient or contaminant loading from the watershed, or to understand impacts carried downstream to Lake Winnipeg, into Hudson Bay and the arctic. For example, climate change impacts include direct lake warming, which intensifies in-lake chemical and biological processes, and increasingly intense precipitation events. It is likely that this has led to increased runoff and more frequent flooding, and hence, increasing nutrient and contaminant transport from the watershed to the lakes, but we have no data to support this speculation. In Lake Manitoba, commercial catch of the most valuable species, pickerel, has declined by more than half since the 1980s. This may be due to pike in-migration through the Portage Diversion, or to high fishing pressure; we have too little information to know the cause. Most recently, in the summer of 2021, zebra mussel larvae were discovered in Lake Manitoba; again, without better information, the impact of this invasive species is a matter of conjecture. Overall, lake management and governance are being decided without adequate scientific support.
The MBGL program deploys moorings to measure physical and biological parameters in the lakes. Through various initiatives, including graduate programs, we also collect nutrient, biological and physical data from the MBGL lakes as well as the surrounding watersheds. Other projects include studying nutrient forcing of algal biomass and associated algal toxins. We look at water quality indicators such as chlorophyll, suspended solids and dissolved organic carbon and can use them to create visualizations such as maps of chlorophyll concentration in surface water. These methods combined with satellite data can be used for early detection of algal blooms and identify potential sites where algal toxins may occur.
Through our multi-disciplinary research the MBGL program will provide biological and physical data to support science-based decision making in the Hudson Bay Watershed, at local, regional and hemispherical scales
