COLUMBUS -- Researchers have found that zebra mussels have built colonies on the sandy and muddy bottom of Lake Erie, a habitat previously thought incapable of supporting the animals.
Since their Great Lakes debut in the mid-1980s, researchers believed that these tiny freshwater bivalves could only colonize hard, underwater surfaces such as rocks, clams and runoff pipes. The new findings are reported this week in the journal Nature.
In terms of potential zebra mussel habitat, Lake Erie is wide open, said Paul Berkman, senior research associate at Ohio State Universitys Byrd Polar Research Institute. More than 90 percent of the Lake Erie floor is a soft substrate. This is a wake-up call.
We found that zebra mussels clearly colonize sand and muddy substrates in the lake, he said, adding that the densities of some zebra mussel colonies exceed 20,000 animals per square meter.
Berkman and his colleagues studied 200 kilometers of the Lake Erie floor from the New York-Pennsylvania border to the lakes western basin. They determined that by 1995, zebra mussels covered about 2,000 square kilometers of the lake beds soft sediment.
We do know that mussels colonize soft substrates and that they are doing this over a significant portion of the lake, Berkman said.
A zebra mussel starts out as a microscopic larva and can attach itself to a single grain of sand or mud. When the animal becomes a juvenile, it starts secreting byssal threads, which serve as anchors to attach the mussel to a stable surface. It continues sending out these threads, picking up more sand grains and creating a mat of cemented sediment.
This creates a hard substrate, Berkman said. By binding sand grains together with their byssal threads, the mussels create a conglomerate, subsequently settled by juveniles, which creates a bed of zebra mussels on the lake bottom.