Aquatic Invasive Species (AIS) Prevention Program and Zebra Mussel Monitoring in Riding Mountain National Park

Zebra Mussels
Zebra mussels (Dreissena polymorpha) are native to eastern Europe. They were first detected in North America in the Great Lakes in the mid-1980s. Since then, they have infested many waterbodies in eastern North America. They were first detected in Manitoba in 2013, when they were discovered in the south basin of Lake Winnipeg. They later also colonized the Red River from the US border to Lake Winnipeg. Since then, they have invaded the Nelson River from Lake Winnipeg to Hudson Bay, as well as Cedar Lake and Lake Manitoba.

Zebra mussels are freshwater hinged mollusks. They are filter feeders that attach themselves to solid surfaces. They breed very quickly, as females can release up to one million eggs each breeding season. After the eggs are fertilized, larvae (called veligers) emerge and are free-floating for up to a month. The larvae are microscopic and do not swim. Veligers float through lake and river currents until they settle on a solid surface. This natural dispersal method means they can easily affect waterways downstream from an invaded area. Zebra mussels have few, if any, natural predators in North America. As a result, they often permanently alter the food web and ecosystems they invade.

Zebra Mussels can have significant negative impacts on people, such as:

·  Increased maintenance costs

·  Damage to equipment such as boats, hydro-electric generating facilities, water intakes and other infrastructure along infested water bodies

·  Injury from sharp shells

·  Potential negative health impacts resulting from increased likelihood of toxic algae blooms

·  Beach closures

They also have negative effects for freshwater habitats, such as:

·  Altering the food web by out-competing native species, like native mussels and other small invertebrates, for food (plankton).

·  Removing large amounts of non-toxic algae (plankton) from the water and leaving behind toxic algae (cyanobacteria) to thrive, causing toxic algae blooms

·  Affecting fish spawning areas by changing the surfaces of rocks and vegetation, impacting the survival of fish eggs

·  Creating clearer water, allowing sunlight to penetrate deeper and changing the habitat by increasing the growth of submerged aquatic vegetation.

Zebra mussels are especially harmful to native mussels, many of which are species at risk. They outcompete these species for food and will attach themselves to native mussels, suffocating them.

An infestation of zebra mussels in Clear Lake presents a real threat of significant and irreversible damage to the lake and downstream waterbodies.

Discovery of Zebra Mussels in Clear Lake
Clear Lake is a unique lake for the prairie parkland area. It is oligotrophic, meaning it has low amounts of nutrients in the lake, giving it a clear look and making it a suitable source of clean, fresh drinking water. Clear Lake is key habitat for 14 fish species, including whitefish, northern pike, white sucker, walleye, and slimy sculpin. Whitefish are the most abundant large-bodied fish in Clear Lake and are usually found in the deeper parts of the lake along with slimy sculpin. Both species are considered ecological indicators of the health of the lake as they require a well-oxygenated lake bottom to survive.

In November 2023, Parks Canada officials removed a clump of live zebra mussels from Clear Lake in Riding Mountain National Park. This prompted the search for further evidence of their presence somewhere in Clear Lake. Over the winter, water samples were collected from Clear Lake and tested for zebra mussel environmental DNA (eDNA) at the Freshwater Institute operated by Fisheries and Oceans Canada in Winnipeg.  In cold water, zebra mussels are less metabolically active and are much less likely to shed eDNA; therefore, zebra mussels may be present despite the negative eDNA results from this winter. Positive eDNA samples can give a better idea of where a population might be located. Sampling continued until the ice was no longer safe and will resume on open water as soon as possible.

Parks Canada staff at Riding Mountain National Park are working with AIS specialists from other Parks Canada administered sites, Members of Keeseekoowenin Ojibway First Nation, the Province of Manitoba’s AIS Unit, and Fisheries and Oceans Canada. The Keeseekoowenin Ojibway First Nation (KOFN) maintains authority and control of fishing station IR 61A on the northwest shores of Clear Lake.

The likelihood of success for any potential eradication action will depend on whether an intervention can happen before significant reproduction and spreading occurs within the lake. Determining with relatively high confidence where they exist in the lake would help to inform potential eradication options.

Timeline

Summer 2011 – Monitoring for zebra mussels in Clear Lake begins.

Summer 2015 – Mandatory Parks Canada AIS inspections and decontaminations begin at Riding Mountain National Park.

Summer 2011 to 2023 – Water samples from Clear Lake and surrounding water bodies are taken and tested for zebra mussel eDNA.

January 2023 – Parks Canada is informed by Fisheries and Oceans Canada of a positive test result for zebra mussel eDNA in a water sample taken at an area known as Boat Cove, in Clear Lake on August 4, 2022.

February 2023 – Parks Canada implements an unprecedented winter zebra mussel eDNA monitoring program in the area to search for further evidence. No more samples tested positive.

May 4, 2023 – Parks Canada announced that trailered watercraft intended for use on Clear Lake must not have been in any other waterbody in 2023 and must undergo an inspection by June 15. Boats that met the requirements had a tag installed that sealed the boat to the trailer. This tag ensured that the watercraft had not been in another waterbody and posed no risk of bringing in aquatic invasive species. If this tag was removed or tampered with, the boat would not be allowed to launch in Clear Lake for the remainder of the 2023 season. All human-propelled vessels (canoes, kayaks, stand-up paddle boards) were required to undergo a Parks Canada AIS inspection, and if needed, decontamination before launching in park waters.

November 2023: Parks Canada is informed by Fisheries and Oceans Canada of multiple water sample tests indicating positive results for zebra mussel eDNA throughout the summer near Boat Cove, in Clear Lake.

November 10, 2023: Parks Canada officials do a physical search Boat Cove and a clump of 48 live zebra mussels was found and removed from the water. Before that, zebra mussels had never been found in Riding Mountain National Park. The discovery was subsequently communicated to the public.

December 2023: Parks Canada holds open house public forums in Onanole and Brandon to discuss the situation, provide information and gather input. An online session was held in January 2024.

January 2024: Parks Canada began collecting water samples from various locations throughout Clear Lake to locate zebra mussels at any life stage with members of Keeseekoowenin Ojibway First Nation, the Province of Manitoba’s Aquatic Invasive Species Unit, and Fisheries and Oceans Canada. On-ice water sampling was prioritized based on areas where the mussels are most likely to colonize first, such as access points like boat launches and recreational beaches. 

The map above shows Clear Lake broken down into 219 sections. Water samples were taken from sections based on priority. 

February 2024: The first set of water samples collected from Clear Lake between January 8 and February 2, 2024, tested negative for zebra mussel environmental DNA (eDNA).

March 2024: The second set of water samples collected from Clear Lake between February 2 and February 20, 2024, tested negative for zebra mussel environmental DNA (eDNA). All high-priority sections have been tested.

April 2024: On-ice water sampling for zebra mussel environmental DNA (eDNA) from Clear Lake ended on April 5, 2024, due to melting ice conditions. All test results from water samples taken throughout the winter of 2024 have been negative. Zebra mussels may be present despite negative eDNA results. In cold water, zebra mussels are less metabolically active and are much less likely to shed eDNA.

VIDEO ASSETS AVAILABLE FOR USE

For use of Parks Canada licensed winter research and sampling video footage, you may obtain a copy by providing us access to your file transfer location so that we can upload the footage to you. Please contact us with your request:
pnmr-media-rmnp@pc.gc.ca.

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