Zebra and Quagga Mussels (Midwest through Southwest)

Despite their highly invasive status, zebra and quagga mussels are not a candidate for consumption because they are highly contaminated with PCBs and the toxin that causes botulism. Zebra and quagga mussels are small mollusks that typically grow no larger than a fingernail. They are native to freshwater rivers and lakes in Eastern Europe and western Asia, but have become invasive throughout the United States, probably as a result of international ship travel. In the mid 1980s, zebra mussels were found in the Great Lakes, and since then have spread to waterways throughout the Midwest. In the late 2000s both species were discovered to have reached as far south and west as southern California. Their spread is cause for concern because they are filter feeders, and their voracious feeding habits often disrupt the ecological balance of lakes — resulting in fewer beneficial microorganisms and therefore less food available for small fish and other native species. These mussels also readily attach themselves to any available surfaces (including boat hulls, underwater pipes, and even smothering native shellfish) further disrupting the ecosystem and also reservoir and water systems.