By Angela Sena
I don’t mean the four-legged variety, but zebra mussels! They are an invasive mollusk species (Dreissena polymorpha) that have been found in many lakes and rivers across the Heartland. Zebra mussels have been discovered in scattered locations along the Missouri River, Lake Lotawana, Smithville Lake, Lake of the Ozarks in the Osage River, Bull Shoals Lake, and Lake Taneycomo in the White River, just to name a few. For those who are water recreationists – boaters, anglers, water skiers, sailors or canoeists – we all need to keep our eyes open for this species and help prevent their spread since there is no known way to stop them once they get a foothold.
Zebra mussels are a group of freshwater mussels with triangular shells and dark bands with prominent ridges. A concavity (or hollow) about midway allows the animal to secrete byssal threads, which allow it to attach to almost any solid surface. They often clump together, and adults are generally ¼ to 1 inch in length. Zebra mussels are native to the Caspian Sea region of Asia, and were accidentally introduced to North America from ballast water of an international ship. They have tremendous reproductive capabilities: a female zebra mussel can produce more than a million eggs during spawning season. The eggs hatch into a larval form (veligers), which are not visible to the human eye, making their detection and eradication difficult. At three weeks, the sand grain-sized larvae start to settle and attach, and feel like sandpaper on solid surfaces.
This invasive species can hitchhike by attaching to boat, canoe and watercraft hulls, lower units and propellers, axles, engine drive units, trolling motors, hitches, and anchor chains. They can also survive in boat bilge water, livewells, bait buckets, and engine cooling water systems. Aside from being an inconvenience for your water craft equipment, they negatively impact the economy by clogging power plant intakes and industrial and public drinking water intakes, and damaging boat hulls and motors. Zebra mussels also harm native ecosystems, and decimate native freshwater mussels and other aquatic animals.
If you enjoy spending your summers on a lake, just like my family, then we all need to do our part. Water recreationalists can help by preventing the spread of the species with a few simple steps:
- Clean – Remove all plants, animals and mud, and thoroughly wash all equipment with hot water spray (104 degrees), especially in small crevices or hidden areas. Most car washes will suffice. If you can’t wash at that temperature, a 10-percent solution of bleach will do.
- Drain – Eliminate all water before leaving the lake, including livewells and transom
- Dry – Allow sufficient time for drying between water events – at least 48 hours.
- Dispose – Dispose of unused bait in a trash receptacle.
- Report – Report any sitings of these species. The U.S. Geological Survey maintains a Nonindigenous Aquatic Species (NAS) website for zebra mussels that shows an up-to-date map of recorded occurrences, and includes a “Report a Sighting” link that allows you to submit a report if you find them.
However, if you do spot a mussel when you’re out enjoying a lake or stream, don’t worry. Not all mussels are unwelcome. In fact, most mussels here in the Heartland are a good thing. Check out these previous Big Blue Thread blogs by EPA’s Craig Thompson: Mussels in the Blue, Mussels in the Blue II: Relative Abundance of Species in the Blue, and Mussels in the Blue III: Water Quality and Threats.
Angela Sena serves as an Environmental Protection Specialist with the Water, Wetlands, and Pesticides Division at EPA Region 7. She has a degree in environmental science and management, and is a native New Mexican and avid outdoorswoman.