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By taking action, we can help protect our waters and prevent further damage!
Zebra Mussels (Dreissena polymorpha) are small, freshwater molluscs easily recognized by their distinctive striped shells, which feature alternating black, brown, and white patterns. Typically measuring 2 to 2.5 cm in length, they have a triangular shape and a flat underside that, using byssal threads, allows them to attach firmly to surfaces.
Native to the Black and Caspian Seas, Zebra Mussels were introduced to North America in the late 1980s through ballast water from ships. Since then, they have spread rapidly across the Great Lakes, severely impacting freshwater ecosystems and infrastructure. These filter-feeders consume plankton and other small particles from the water and can survive out of water for up to 18 days, making them highly mobile. Their rapid spread through lakes, rivers, and reservoirs poses significant environmental and economic challenges.
Zebra Mussels were first discovered in the Great Lakes in the 1980s, having arrived via ballast water from transatlantic ships. Since then, they have expanded across North America and are now found in major watersheds, including:
In October 2023, Zebra Mussels have been found in the Wolastoq (St. John River) watershed. They reproduce at an alarming rate, with females capable of releasing up to one million eggs per breeding season, making containment and eradication difficult.
Zebra Mussels pose severe threats to freshwater habitats by outcompeting native species and altering ecosystem dynamics. The negative impacts include:
Zebra Mussels have far-reaching effects on recreational and industry water use, including:
Zebra Mussels threaten many native and at-risk species by:
In Nova Scotia, Zebra Mussels have been determined to be a significant potential threat to Yellow Lampmussel (Lampsilis cariosa) and Brook Floater (Alasmidonta varicosa) due to increased competition for resources and space and potential changes to host fish availability.
Although studies have not specifically examined the impact of Zebra Mussels on Atlantic Salmon (Salmo salar) or Atlantic Whitefish (Coregonus huntsmani), these invasive mussels can disrupt food webs and habitats by filtering out plankton and competing for both food and space.
Once Zebra Mussels establish a population in a water body, removing them is nearly impossible. This makes prevention the most effective strategy to keep our lakes and rivers free from them.
Zebra Mussels reproduce by releasing microscopic larvae, called veligers, into the water. These veligers cannot swim on their own and rely on currents to move downstream. They cannot travel upstream or between unconnected lakes without outside help—unfortunately, human activity often serves as a pathway of introduction.
Since veligers are too small to be seen, they can easily be unknowingly transported in:
If this contaminated water is released into an uninfected lake or river, a new outbreak can quickly take hold.
Since Zebra Mussels can also survive out of water for up to 18 days in high humidity, it is critical for water users to:
Remove any visible mussels, plants, or debris from boats, trailers, and equipment.
Empty all water from live wells, bilges, and bait buckets before leaving a water body.
Allow boats and gear to dry before entering another water body.
Spread awareness about Zebra Mussels and how they impact ecosystems and recreation.
Encourage responsible boating and fishing practices.
Zebra Mussels pose severe threats to freshwater habitats by outcompeting native species and altering ecosystem dynamics. The negative impacts include:
They colonize hard surfaces, including fish spawning sites, reducing the survival rate of fish eggs and native mussels.
By consuming large amounts of plankton, they disrupt the balance of the ecosystem.
While this might seem beneficial, clearer water allows more sunlight penetration, leading to:
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