Parts of Lake Huron and Georgian Bay around Grey and Bruce counties have been identified as highly stressed in a recently released environmental map.
A team of researchers who are part of the Great Lakes Environmental Assessment (GLEAM) project examined 34 stressors, including coastal development, pollutants transported by rivers from agricultural and urban land, fishing pressure, climate change and invasive species. Using data from various agencies, organizations and researchers, the map shows how different stressors can be combined to assess the overall health of the ecosystem.
While the map shows that Lake Huron and Georgian Bay are in relatively good shape compared with lakes Erie and Ontario, some areas along the shorelines of Lake Huron and Georgian Bay, including in the Grey and Bruce areas, are considered highly stressed, according to the map’s index. The index ranks stress levels on a scale from 0 to 100%.
An area on the east side of the Bruce Peninsula, including all of Owen Sound Bay and Colpoy’s Bay, appear as red on the map, indicating a high level of stress on the ecosystem when compared with the rest of the Great Lakes. A large area on the west side of Bruce County along the shoreline stretching from Kincardine in the south to South Bruce Peninsula in the north also appears as red, meaning there are probably at least 12 to 15 different stressors hitting that area.
“When you add all the stressors up, what you see is Owen Sound, Kincardine, a little bit around the bottom end of Georgian Bay, which is heavy cottage country, you see them showing up as being at the higher end of stress,” David Allan, the project’s lead researcher and a professor of aquatic sciences at the University of Michigan’s School of Natural Resources and Environment, said Monday. “The rest of (the area around Grey-Bruce) you see as moderately to minimally stressed.”
Allan explained that the stressors are defined as human impacts such as physical, chemical or biological disruptions that potentially have adverse effects on people, plants and animals.
“Those stressors vary from ones which have a big impact, according to the experts, to ones that have a very little impact,” said Allan.
Stressors identified in the Grey and Bruce areas include shoreline structures such as docks and dams on tributaries.
Allan said dams, such as Denny’s Dam on the Saugeen River and the Mill Dam on the Sydenham River, as having a pretty big impact on the ecosystem locally.
“Dams will disrupt the natural flow, the natural sediment regime and the natural nutrient regime of a river,” said Allan. “Dams in the watershed, obviously not in the lake, were one of the factors.”
Climate factors such as decreased ice coverage and water level changes were also major stressors in the Grey-Bruce area.
“Another measure we made of climate vulnerability, of climate susceptibility, was simply areas that were within the three-metre depth contour,” said Allan. “So if lake levels were to drop, the shallow areas are most likely to be impacted.”
Other sources of stress in the Grey-Bruce area include mines, recreational areas such as beaches and power plants such as the Bruce Power nuclear plant in Kincardine. Commercial fishing in the Cape Croker and Saugeen Shores areas, ballast water invasive species risk in Owen Sound harbour, invasive species taht have already arrived such as round goby, and nitrogen and sediment from the Saugeen and Sauble rivers were other factors locally, Allan explained.
While there are some local areas that show up as highly stressed, it doesn’t compare to lakes Michigan, Erie and Ontario. Lake Ontario, for example, is almost entirely red on the map.
While there was no one from the Grey-Bruce area involved in the work, Allan said there were participants from the University of Windsor and Queen’s University in Kingston. Advice was also sought from people at the University of Toronto.
“We gather data sets,” said Allan. “It’s not the same thing. You wish you could talk to an expert at every point of the map.”
Allan said the map was produced to assess human impact on ecosystems and help guide shoreline management and restoration projects on the lakes.
“The cumulative impact map provides a quantitative perspective on how best to protect critical natural resources such as beaches, boating and fishing that support a vibrant tourism industry, as well as commercial fishing which remains important to local economies,” Allan said. “Conducting this analysis at the scale of the entire Great Lakes basin fills an important gap in strategic prioritization to protect the Great Lakes and the services they provide to society.”
The GLEAM website can be found at www.greatlakesmapping.org. To view the individual data layers showing individual stresses click on the “Lake Stressors” tab, then click on “View maps interactively.” The interactive map will appear and there is a tab in the upper right corner with a drop-down menu of individual stressors.
Data will continue to be acquired and the stress maps will be regularly updated.