There have been considerations made to use filter feeding crustacean colonies as a “natural” water filtration system. The Alabama Aquatic Biodiversity Center is currently promoting the restoration of freshwater species in order to filter ponds and streams in Alabama. The thought is that these filter feeders will remove bacteria and other harmful pollutants as they draw in water. In theory this will work because one mussel can process up to 12 gallons of water per day, so a colony has the ability to process thousands of gallons per day.
There are two main problems:
- Mussels out of control
In the 1980’s a species of mussel was introduced into the Great Lakes. Since then the population of the Zebra Mussel has exploded. This species is invasive and has caused numerous problems within the Great Lake system. These mussels compete with native species for food, and are literally whipping out native mollusk species within the great lakes. Zebra Mussels have a tendency to attach themselves to any hard underwater surface, including water intake pipes, native mollusks, turtles, boats, and docks. When the mussel attaches to a native clam, the clam is no longer able to breathe because it’s breathing apparatus has been blocked, causing the clam to drown. Zebra Mussels cut off the water supply to a northern Michigan town for three days because a mass amount of the species had clogged the intake pipe. The mussel’s consumption of plankton has far more negative effect than just food competition for native species the obliteration of plankton in the great lakes does clear up the water; however this has terrible effects for the overall lake ecosystem. The clearer water allows UV rays to penetrate deeper into the lake, where they have destructive effects on fish eggs. The clearer water also aids in the algal bloom of the quick grown photosynthetic algae. This alga attracts large numbers of birds and other wildlife. This increase in species leads to an increase in amount of feces, with contains E. coli that can be fatal to humans.
- Clear Water Doesn’t Mean Clean Water
Just because water becomes clear when filter feeders are present doesn’t mean that the water is necessarily clean. The clearness of the water is derived from the removal of plankton and algae. This doesn’t mean that chemical pollutants that have been introduced into the water system will be removed by filter feeders. Mollusks remove solid plankton from the water, not a dissolved solution of pollutant and water.
The striking effects of the mollusks on the great lakes seems like they are right out of a Sci-Fi movie; Monstrous mussels demolishing a town’s water supply, smothering out entire ecosystems by demolishing plankton populations, and drowning out the competition. Lobsters and turtles caught in the region are literally drug from the water covered from head to tail in the dime sized zebra mussels.