Quagga Mussels (Dreissena bugensis) are an invasive species of freshwater mussel native to the Dnieper River drainage in Ukraine. They were introduced to North America in the late 1980s through ballast water discharged from transoceanic ships. Since then, they have spread rapidly throughout the Great Lakes region and many inland waterways in the United States and Canada. These mussels are closely related to the similarly invasive Zebra mussels (Dreissena polymorpha), but they are distinct in their adaptability and environmental impact.
Identification and Characteristics
• Scientific Name: Dreissena bugensis
• Shell Size: Typically 20-25 mm (0.8-1 inch) in length but can grow up to 40 mm (1.6 inches).
• Shell Appearance:
• Rounded or fan-shaped with subtle ridges.
• Colour varies from pale cream to tan or brown with darker stripes, though the pattern may fade with age.
• Unlike Zebra mussels, Quagga mussels have a more rounded underside that allows them to sit flat on surfaces.
Habitat
• Depth Range: Quagga mussels thrive in waters as deep as 130 metres (426 feet), deeper than Zebra mussels.
• Water Conditions: They prefer cooler, less salty, and nutrient-rich waters, though they are highly adaptable and can survive in diverse environments.
• Substrate: Attach to hard surfaces like rocks, wrecks, boat hulls, pipes, and even soft sediments, making them more versatile than Zebra mussels.
Introduction and Spread
• Pathway to North America:
• Arrived in 1989 via ballast water from ships entering the Great Lakes.
• First discovered in Lake Erie, they quickly spread to other lakes in the system and inland waters.
• Current Range:
• Found in the Great Lakes, Finger Lakes, the St. Lawrence River, and as far west as California and Arizona.
Ecological Impact
1. Water Filtration and Ecosystem Disruption
• Quagga mussels are filter feeders, capable of filtering up to 1 litre of water per day per mussel.
• This removes significant amounts of plankton from the water column, which disrupts the food chain, starving native fish and other aquatic life.
• Their filtration increases water clarity, which might seem beneficial but allows sunlight to penetrate deeper, causing algal blooms and other ecosystem shifts.
2. Invasive Dominance
• They outcompete native mussels and other benthic organisms for resources, often leading to local extinctions.
• Quagga mussels dominate over Zebra mussels in many areas because they can colonize soft sediments as well as hard surfaces.
3. Impact on Fish Populations
• By altering the availability of food sources, Quagga mussels indirectly affect fish populations, particularly species dependent on plankton, like small forage fish.
Economic Impact
1. Infrastructure Damage
• Quagga mussels clog intake pipes, water treatment facilities, and hydroelectric plants, requiring costly maintenance.
• Their attachment to boats, docks, and equipment increases cleaning and repair costs.
2. Tourism and Recreation
• Their sharp shells create hazards for swimmers and beachgoers, and their colonies can disrupt water-based recreation.
• Dead mussels wash ashore, producing foul odours as they decay.
3. Costs
• Annual management and cleanup costs for invasive mussels in North America are estimated in the billions of dollars.
Control and Management
1. Boat Cleaning Protocols
• Inspect, Clean, Drain, and Dry:
• Remove all visible mussels and aquatic plants from boats, trailers, and gear.
• Drain water from bilges, live wells, and engines.
• Allow equipment to dry completely before entering another body of water.
2. Chemical Treatments
• Certain chemicals, such as potassium chloride (KCl) or molluscicides, can be used in closed systems like water intake pipes.
• Care must be taken to avoid harming native species.
3. Education and Awareness
• Outreach programs like Stop Aquatic Hitchhikers! and Clean, Drain, Dry initiatives inform the public about preventing the spread of invasive species.
4. Research
• Scientists are studying potential biological controls, such as pathogens or predators, to target Quagga mussels specifically without harming native species.
Quagga Mussels vs. Zebra Mussels
Characteristic
Quagga Mussels
Zebra Mussels
Shape
Rounded underside; sits flat.
Flattened underside; sits on edge.
Habitat
Hard and soft surfaces; deeper waters.
Prefers hard surfaces; shallower waters.
Tolerance
Cooler, nutrient-poor environments.
Warmer, nutrient-rich environments.
Dominance
Outcompetes Zebra mussels in many areas.
Often displaced by Quagga mussels.
Presence in Skaneateles Lake
• Quagga mussels are well established in Skaneateles Lake, one of the cleanest lakes in the Finger Lakes region.
• Their colonization is evident on wrecks, lines, and underwater structures, including dive sites like the intentionally sunk fiberglass sailboat.
• Their impact on the lake’s ecosystem includes reduced plankton levels, affecting native fish populations and altering nutrient cycling.
Further Resources
1. Finger Lakes Institute
• A leading organization studying invasive species in the Finger Lakes.
2. USGS Nonindigenous Aquatic Species Database
• Tracks the spread and impacts of Quagga mussels in the U.S.
3. Ontario Invasive Species Centre
• https://www.invasivespeciescentre.ca
• Provides tools and guidelines for managing invasive species in Canadian waters.
Conclusion
Quagga mussels are a dominant invasive species in North American freshwater ecosystems, including Skaneateles Lake. Their ability to outcompete native species and disrupt ecosystems highlights the importance of prevention, control, and awareness. While they pose ecological and economic challenges, ongoing research and community-led efforts aim to mitigate their impact and protect local waterways.