Quagga mussels (Dreissena bugensis) are a highly invasive freshwater mollusk originating in the Black Sea and Caspian Sea region of Eurasia. They were first detected in North America in the Great Lakes in the late 1980s, introduced primarily through contaminated ship ballast water. These mollusks pose a profound threat due to their rapid reproduction and filter-feeding efficiency. A single mussel can filter over a liter of water per day, removing phytoplankton that forms the base of the native aquatic food web and fundamentally altering the ecosystem. Their ability to attach to virtually any hard surface also leads to severe economic consequences, particularly by clogging water intake pipes and critical infrastructure.
Individual Prevention Protocols
Preventing the spread of quagga mussels relies heavily on recreational water users strictly applying the “Clean, Drain, Dry” protocol. This three-step process is the most effective defense against accidental transport of mussels between water bodies via boats, trailers, and gear. The “Clean” step involves a thorough inspection of the watercraft, trailer, and all associated equipment to remove any visible plants, animals, mud, or debris.
Cleaning must be performed away from the water’s edge, and removed material must be disposed of on dry land, not washed into a waterway. The “Drain” component requires emptying all water from the boat, including the bilge, live wells, ballast tanks, and engine cooling systems, before leaving the access area. Since the microscopic larval stage, known as veligers, can survive in small amounts of standing water, completely draining all compartments is essential.
The final step is “Dry,” which uses desiccation to kill any remaining adult mussels or veligers. Required drying times are highly dependent on local climate, including temperature and humidity, and can range significantly. In hot, dry climates, the minimum drying time may be about five days, but in cooler or more humid conditions, this period can extend to 30 days.
Watercraft with complex raw water systems, such as inboard motors, air conditioning units, or ballast tanks, frequently require an extended drying period of up to 30 days regardless of outside temperature. All fishing gear (waders, nets, buckets) and paddle sports equipment (kayaks, stand-up paddleboards) must also be cleaned and dried. Using hot water, ideally over 140°F, for a low-flow rinse on any surface that contacted the water serves as an immediate decontamination step if a full drying period is not feasible.
Infrastructure Eradication Techniques
Controlling established quagga mussel populations in large-scale municipal and industrial infrastructure requires specialized techniques beyond individual prevention. Water management agencies and power plants rely on a combination of mechanical, thermal, and chemical methods to address biofouling within piping systems and intake structures.
Mechanical Control
Mechanical methods use physical force to remove attached adult and juvenile mussels. Techniques include high-pressure hydro-blasting, which uses powerful water jets to dislodge colonies, and manual scraping by divers. A technique called “pigging” involves forcing a specialized scraping device through pipelines to scrape mussels from the interior walls. While effective, these methods require careful collection and disposal of the mussel debris to prevent re-colonization or environmental contamination.
Thermal Control
Thermal control utilizes heated water to kill mussels without introducing chemicals into the system. Exposing mussels to water heated to 35°C (95°F) for two hours can achieve nearly 100% mortality. This method is deployed by temporarily isolating a section of the pipe or intake structure and circulating the heated water through it.
Chemical Control
Chemical treatments manage large infestations but require strict regulatory compliance due to environmental concerns. Oxidizing agents, such as chlorine, ozone, or potassium permanganate, are introduced into intake systems to kill the mussels. Non-oxidizing molluscicides, typically proprietary compounds, are also used and can be effective with shorter contact times. These applications are almost exclusively limited to closed systems or specific infrastructure to minimize impact on the broader aquatic ecosystem.
Biological and Experimental Controls
Biological and experimental control methods aim to target mussels with greater specificity or through non-traditional means. The most commercially available biological control agent uses a naturally occurring, killed strain of the bacterium Pseudomonas fluorescens. When quagga mussels filter feed, they ingest these bacterial cells, which rupture the lining of their digestive system, leading to mortality.
This method is environmentally sound because the mussels treat the bacteria as a food source and do not close their shells, unlike when exposed to some chemical agents. Researchers are also investigating native fish predators for site-specific control. Redear Sunfish prey on juvenile and adult mussels, while Bluegill Sunfish consume the free-swimming veliger larvae, offering potential targeted pest management in open-water systems.
Non-chemical technologies are being explored to deter or disturb mussel settlement and growth. Acoustic technologies show promise, using solid-borne sound (8 to 10 kilohertz range) to potentially prevent the attachment of juvenile mussels in pipes. Low-frequency magnetism and weak electric currents are also being researched for their ability to interfere with the mussels’ shell formation, causing a lethal loss of calcium.