Several formerly productive beds have already been decimated by zebra mussel growth. Zebra mussels attach to boat docks and boat hulls. They plug water intake ports, causing outboard motors to overheat. Huge deposits of dead zebra mussel shells can wash on beaches, causing foul odors and cutting bathers' feet with their sharp shells. In Lake St. Claire, the filtering action of zebra mussels has caused clearer water.
More sunlight reaches the bottom and there is now more vegetation.
Walleye are being replaced by other fish and may disappear because they are no longer reproducing successfully. Other formerly productive fisheries are also in decline caused by loss of food source and spawning grounds due to zebra mussel infestation. The European comunity has been unable to find a control after two centuries of infestation. In the Great Lakes, no chemical toxicant has been developed that is both feasible for widespread use and not toxic to other aquatic species. In some parts of Europe, large diving duck populations have actually changed their migratory pattern in order to forage on zebra mussel beds.