Zebra mussels (dreissena polymorpha) can grow up to 50 mm in length and are named afther the bands of colors found on their shells. Originally discovered in 1771 they were found Balkans, Poland, and the former Soviet Union. They expanded rapidly through most of Europe in the late 18th and early 19th century following the massive growth of canals during that period and were first introduced to North America in 1985 when a eastern European cargo ship opened its stopcocks and released its ballast, that contained, among other things, veligers, the zebra mussel's larval form.
Less than 20 years after their inital introduction, zebra mussels are known to be in 20 states including, Michigan, Connecticut, and Wisconsin. Although extremely effective as water filters, they are an absolutely pain, especially in the United States where they have no natural predators. The mussels will colonize on just about everything. They have been known to sink navagational buoys due to their weight, clog engine cooling systems in boats, causing overheating and other things. However, the worst is probably their colonization of water intake valves, the town of Monroe, Michigan was shut down in December 1989 for 56 hours when a combination of zebra mussels and ice cloged the city waterworks' only intake valve. Two years later in October, Detroit Edison had one of their screenhouses cleaned after 2 zebra mussel spawning seasons and had 30 tons of zebra mussel debris hauled to the dump.
There are many methods of ridding zebra mussels, none plausable due to cost overruns or damage to the Great Lakes ecosystem. Here are a few:
- Chemical Molluscicides: Oxidizing (chlorine, chlorine dioxide) and Non-oxidizing
- Manual Removal (pigging, high pressure wash)
- Dewatering/Desiccation (freezing, heated air)
- Thermal (steam injection, hot water > 32C)
- Acoustical Vibration
- Electrical Current
- Filters, Screens
- Coatings: Toxic (copper, zinc) and Non-toxic (silicone-based)
- Toxic Constructed Piping (copper, brass, galvanized metals)
- Carbon Dioxide Injection
- Ultraviolet Light
- Anoxia/Hypoxia
- Flushing
- Biological (predators, parasites, diseases)