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Invasive species, climate change behind bird and fish die-offs: ecologist

'These types of botulism-related mortality events may become more common as we head into the uncertain world of climate change,' said David Featherstone, senior ecologist with the Nottawasaga Valley Conservation Authority
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A photo taken by a staff member with Georgian Bay Forever of a dead duck on Wasaga Beach.

Experts have confirmed the recent bird and fish die-off that brought hundreds of carcasses to the shores of Wasaga Beach and area is likely botulism, and it likely has a lot to do with invasive species. 

Last month, several residents and visitors to Wasaga Beach Provincial Park began to report finding dead birds along the shore. 

Park Superintendent John Fisher confirmed in late October there was a bird and fish die-off event. 

Brian Stevens, a wildlife pathologist with the Canadian Wildlife Health Cooperative, said his organization was first informed of the die-off on Oct. 18. 

“We received reports of about 200 birds from Wasaga Beach on Oct. 18,” said Stevens in an email. “Since that time, other reports have slowly trickled in.” 

While the Canadian Wildlife Health Cooperative, based out of the University of Guelph, intends to examine organs from the dead birds found on local shores, the evidence so far points to botulism. 

“The birds that we examined are in good body condition and there is no evidence of underlying disease on necropsy examination,” said Stevens. “The species of birds affected – fish/mollusc-eating water birds such as long-tailed ducks, red-necked grebes, and ring-billed gulls – and the overall good condition that these birds are in is highly suggestive of a Type E botulism outbreak.” 

David Featherstone, a senior ecologist with the Nottawasaga Valley Conservation Authority, said this most recent die-off is not an isolated event. It’s been happening on the shores of Georgian Bay since the 2010s. 

Along Lake Huron, there have been bird and fish die-offs since the late 1990s. While there are many factors impacting the health and mortality of birds and fish in Lake Huron, these die-offs can be linked to invasive species, and even climate change, according to Featherstone and other experts with eyes on the lake. 

The conditions of the die-offs over the last 10 years share commonalities: warm waters, filamentous algae growing and dying off on the rocks, and two invasive mussels. 

“There’s a really interesting food chain connection to these bird die-offs,” said Featherstone. “Botulinum and bacteria develop in the rotting algae, it’s picked up in the food chain by filter feeders like the invasive Zebra and Quagga mussels and some native invertebrates.”

According to the Nottawasaga Valley Conservation Authority, Zebra and Quagga mussels are invasive species that have become prevalent in Lake Huron including Georgian Bay. They add filtration to the water in excess, because of their numbers, and bring sunlight deeper into the water, allowing more algae to grow. 

The invasive mussels are eaten by some forms of waterfowl and by another invasive species, the round goby fish. Those gobies are eaten by the endangered Lake Sturgeon fish that currently have a stronghold in the Nottawasaga River, which they use for spawning. 

Eventually, as the birds and fish eat the bottom feeders that have ingested the rotting algae, the bioaccumulation of the botulinum toxin causes botulism disease in the birds and fish, and they will become paralyzed and die – sometimes by drowning. 

“The Zebra and Quagga mussels seem to be a real vector,” said Featherstone. “And I think climate change might play a role. There’s a connection between extreme storm events, more nutrients coming into shoreline areas and more algae being produced.” 

In the last major storm event in October, Collingwood’s wastewater treatment plant was overwhelmed and some untreated wastewater was sent to Georgian Bay. 

Events like that, said Featherstone, have the potential to drive additional algae growth and die-back because of the nutrients spilling into the shore area. 

“This is potentially an added source for botulism to develop from,” said Featherstone. “These types of botulism-related mortality events may become more common as we head into the uncertain world of climate change.” 

Gary Wheeler, spokesperson for the Ontario Ministry of the Environment, Conservation and Parks, said the latest bird die-off appears to be affecting fewer birds than the large event in 2011, which left an estimated 8,000 to 9,000 birds and fish dead and washed up on the shore of Wasaga Beach Provincial Park. 

In the latest die-off, Wheeler said parks staff have found the carcasses of white-winged scooters, long-tail ducks, common golden eyes, as well as sturgeon, salmon, and carp fish. 

David Sweetnam, executive director of Georgian Bay Forever, reported hundreds of dead birds washed up on Wasaga Beach, Midland, Collingwood, and Tiny Township last month. 

He said the die-offs are not necessarily caused by climate change in the first place, but they are “exacerbated” by climate change. 

“Climate change is adding stress, and allowing invasive species to take hold,” said Sweetnam during a webinar on water levels that was part of a series hosted by Georgian Bay Association and Georgian Bay Forever. 

According to Featherstone, the bird and fish die-offs illustrate the importance of working to prevent invasive species from getting into local lakes. 

Zebra and Quagga mussels first arrived in the Great Lakes in the 1980s from ballast water discharged by large ships from Europe. 

“Unfortunately, the invasives that are in are already in,” he said. “Any efforts that municipalities, companies, and private citizens can do to keep invasive species from coming in and then spreading … to stop that introduction of new species is always a good thing.” 

One of the important ways of preventing the spread of invasive species is a thorough cleaning of marine equipment and construction equipment used along shorelines, according to experts. 

Ontario’s Invading Species Awareness Program encourages boaters to drain all water from the motor, live well, bilge, and transom wells while on land, and to clean all recreational equipment with a high-pressure wash, hot water, or to let it dry in the sun for at least five days. 

You can learn more about invasive species and how to prevent their introduction through the Invasive Species Centre website here and via the Nottawasaga Valley Conservation Authority website here.

The Ministry of Northern Development, Mines, Natural Resources and Forestry is reminding people to keep pets away from dead birds or fish, and to report dead or dying waterfowl to the Canadian Cooperative Wildlife Health Centre at 1-866-673-4781. 

To report fish die-offs, contact the Ministry of Northern Development, Mines, Natural Resources and Forestry at 1-800-667-1940. 




Erika Engel

About the Author: Erika Engel

Erika regularly covers all things news in Collingwood as a reporter, photographer and editor. She has 12 years of experience as a local journalist
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