Northern Bruce Peninsula council report on introduced species in Lake Huron.
John Rodgers, the vice-chair of the Bruce Peninsula Biosphere Association, gave a presentation to council regarding three introduced species in the lake and the movement of phosphorus.
Rodgers said there are three species that play a role in climate change.
He said that one issue along Stokes Bay is algae that washes up along the shoreline. The algae forms big mats that are black in colour, and are particularly noticeable when they rot and cause a bad odour.
That algae can also cause issues with turbidity.
The association is mainly concerned with introduced species using up all of the natural phosphorus in the Great Lakes.
“The lakes are now considered to be phosphorus deficient,” said Rodgers. “There’s really not enough phosphorus out there to generate the plant life required to support the fisheries that we’ve come to expect.”
He explained to council a main cause was the introduction two species of mussel – the zebra mussel, and the quagga mussel.
“Zebra mussels came first, and they cleaned all the phosphorus from the upper part of the water column,” he told council. “Quagga mussels came next, and they’ve cleaned the phosphorus out of the lower part of the water column because they live a little bit lower.”
Rogers says that it gets more complicated, because phosphorus levels vary from the open waters of the lake compared to the shoreline, particularly within the bay.
The mussels eat plankton in the water, and their waste is high in phosphorus. At the depths were the mussels live, their waste fertilizes the algae. Because the water is clearer where the mussels feed, the sunlight can better penetrate to help the algae photosynthesize, and then after a storm event is free to wash up on shore.
In 2024, the water was around a degree warmer than last year, and that means it was easier for the algae to proliferate.
The Bruce Peninsula Biosphere Association constantly works to mitigate drastic changes in phosphorus levels, and keeping them at a balanced level.
Rodgers said that the association is hoping to hold shoreline workshops with residents to try and prevent phosphorus levels from getting too high. Measures include reducing shoreline hardening, planting native plants to prevent soil erosion, Lastly, a measure that could be used is to promote cover cropping.