They are among us:
By the time we first heard the term, "invasive" or "invading" species, Zebra Mussels were already well established in Mississippi Lake. The earliest folks to have a personal experience with them was our volunteer marker buoy crew, when retrieving buoys after a summer in the water. The their tiny shells cut like a surgical scalpel. Gone are the days when we waded, barefoot, into Mississippi Lake.
Zebra Mussels live in fresh water and were first catalogued in the rivers and lakes of southern Russia (Eurasia). It is thought that they found their way into the ballast tanks of ocean-going freighters and were dumped into the St. Lawrence River with bilge water. From the river and the Great Lakes, they have found their way into many lakes and rivers in anglers' bait wells and marine engines, becoming widespread in North America.
The good news:
A single Zebra Mussel consumes up to one litre of water per day, filtering out microscopic material in the water. The filtering process removes suspended material, resulting in increased water clarity. Clarity is good.
The not-so-good news:
Increased water clarity permits sunlight to penetrate to greater depths, allowing aquatic plants to fluorish, choking rivers, waterways and waterfronts. The tiny mussels foul water intake pipes in municipal water systems and hydro electric plants.