`Mussel power' to clean is clearly evident

Magothy: A mollusk's sudden proliferation casts a new, healthy light on the state of the Chesapeake watershed.

August 09, 2004|By Rona Kobell | Rona Kobell,SUN STAFF

A mysterious mussel no bigger than a fingernail is attaching itself to boat ropes, crab pots and anything else it can latch onto in the Magothy River. But nobody is complaining, because the native creature's filtering power is helping to make the water clear as an aquarium.

It's so clear that boaters can count the stripes on the yellow perch, point out crab shells on the bottom and count the rocks embedded in underwater sand. Water grasses, often scarce because of algae blooms that block sunlight, are growing chest-high in some areas.

And scientists, accustomed to finding only 2 feet of clear water this time of year, are stunned to measure light reflecting into the river more than 5 feet deep.

"This is what can happen. This is mussel power," said Roger Newell, a University of Maryland scientist who says the Magothy's summer clarity proves the essential role filter-feeders can play in cleaning up the Chesapeake Bay.

"This is not an academic exercise. It's not a figment of imagination. You can see it for yourself," Newell said.

Scientists don't know much about the Mytilopsis leucophaeata, also known as the dark falsemussel. Few have studied it -- it's not exotic enough to cause concern, like the zebra mussel, which is blocking waste-discharge pipes and disrupting ecosystems in the Great Lakes.

Nor is it large enough to be economically significant, like the Asian oyster that Maryland and Virginia scientists are studying to decide whether they should introduce it into the bay. This is not the kind of mussel that works well with a garlic sauce and a glass of sauvignon blanc.

What researchers can agree on is that the mussel, which thrives amid low salinity and is known to populate area rivers in small numbers, began popping up after Tropical Storm Isabel last fall and increased with the rains this spring. The rains reduced salinity in the water, providing excellent breeding conditions.

The mussel has surfaced in other Anne Arundel County rivers, including the Severn and the South. It has also been seen in the Chester and the Corsica on the Eastern Shore, where the water clarity has astounded residents who were reeling from months of sewage spills at a Centreville treatment plant.

But they have come into the Magothy by the "hundreds of millions," said Chris Judy, the shellfish program director for the state Department of Natural Resources.

"We don't know why they picked the Magothy," Judy said. "Anyone I've spoken to is pleased to see them there."

One cup an hour

The mussels, which attach themselves to hard surfaces with hair-like appendages known as cilia, feed on algae. But they also take in sediment, silt and nutrients that cloud the water.

Newell, who studies filter-feeders at the Horn Point Laboratory in Cambridge, estimates that the tiny mussel can filter about one coffee cup of water per hour -- a fraction of the several gallons an hour that he says the native oyster can filter.

Judy said the mussels aren't solely responsible for this water clarity. Some rivers that don't have the mussel are also reporting clearer water, and there seem to be a lot more clams this year than usual.

But scientists who live along the Magothy are convinced that the dark mussel is letting in the light.

"The question I keep asking myself is, `If the mussels aren't making the water clear, then what's doing it?' Because if we could figure it out, then maybe we could do more of it," said Peter Bergstrom, a fisheries biologist with the government's Chesapeake Bay Program.

Like many other scientists who noticed the mussels, Bergstrom at first feared they were the invasive zebra mussel. Once he learned they were native, he could get back to celebrating the water clarity near his home between Old Man Creek and Cattail Creek. In both creeks, readings showed more than 5 feet of transparency -- twice as good as the best summer conditions he has seen since he began measuring 13 years ago.

Last week, Christopher Conner and Lou Etgen, who grew up on the Magothy, set out in Conner's 22-foot Key West motorboat to measure for themselves. Using a Secchi disk, a Frisbee-like device attached to a line that measures the depth of water clarity, Etgen found clear water more than 5 feet deep in several spots in the river.

"It's amazing to me. I've spent 30 years here. It's never been this clear," said Etgen, who works for the nonprofit Alliance for the Chesapeake Bay. As the boat pulled away, it left behind a white streak of turmoil rarely seen in the usual summer murk.

He and Conner also found crab traps like one belonging to Riverside Drive resident Greg Jones -- devoid of crabs, but encrusted with pinecone-like clusters of tiny mussels. On another dock, a boat rope hanging in the water was so covered with mussels that Etgen could barely lift it out.

Grasses coming back

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