Fewer mollusks in Lake St. Clair
Thursday, July 10, 2003
By Gene Schabath / The Detroit News
Zebra mussels need hard surfaces such as clams to cling to. But the mussels have wiped out the clam population in Lake St. Clair.
Zebra mussels are having a tough time surviving in Lake St. Clair and scientists know the cause: a lack of clams.
Zebra mussels need a hard surface to survive on and the only hard surface on the lake bottom used to be the native clam population.
But the zebra mussels have wiped out the native clams -- hundreds of millions of them, scientist say -- during the 15 years since they were accidentally introduced into the lake from a passing freighter.
Zebra mussels, once the scourge of Michigan lakes, are still a problem, even though they are becoming fewer in number in Lake St. Clair. Their numbers are still high in inland lakes and the Great Lakes.
They continue to be blamed for clogging water intake pipes, wiping out other aquatic species such as clams and disrupting spawning habitat. And they sometimes cause a fishy taste in municipal drinking water, said Mike Thomas, a Michigan Department of Natural Resource fish biologist.
Without the hard surface, few of the developing mollusks make it to adult life, said Doug Hunter, an Oakland University biology professor who studies zebra mussels.
That has left a population of zebra mussels made up of mostly juveniles, he said.
"There has been a dramatic shift from adult zebra mussels in Lake St. Clair in 1990 to juvenile zebra mussels in 2001," Hunter said.
One upside of zebra mussels is that they act as a filtering agent. With fewer of them, the water is murkier than it used to be, said Chuck Bellmore, supervisor of the Mount Clemens drinking water plant, which draws its water from Lake St. Clair.