State surveys health of its coastal bays

Changes: Algae blooms, toxins and development make stabilizing the salty bays of Maryland a growing challenge.

March 15, 2001|By Heather Dewar | Heather Dewar,SUN STAFF

OCEAN CITY - As morning mist softens the hard edges of the townhouses lining Isle of Wight Bay, three men haul up a small dredge within shouting distance of the concrete shore.

Inside, amid the seaweed and soda bottles, is a shellfish smorgasbord: starfish and clams; rock crabs and spider crabs; ancient, armored horseshoe crabs. And a half-dozen fat female blue crabs, wider than the palm of a big man's hand.

"This bay has a lot more variety than the Chesapeake," says Jim Casey, one of the three state Department of Natural Resources biologists aboard the skiff. "What we're trying to do now in the Chesapeake is restore [shellfish] populations. Over here, [the job is] stabilizing it."

Stabilizing the health of the salty bays along Maryland's coast inside Assateague and Fenwick islands is becoming an ever-bigger challenge. Upstream lie some of the state's densest concentrations of poultry houses and farms. Downstream are booming developments, in a county where the population is expected to grow by 40,000 people - almost doubling - in the next 20 years.

The sea grass beds are still dense and the fishing is still good, but there are worrisome signs.

Among the troubles that surfaced last summer are mats of dense algae in Ocean Pines canals, algae blooms that caused ugly brown tides and water samples showing low-level infestations of two toxic microorganisms - Pfiesteria and a new pest, chattonella - that can kill fish and make people sick.

Scientists don't know what's causing these changes or what the consequences are. But beginning this spring, they will be trying to find out, as DNR biologists conduct the first comprehensive surveys of water quality in Chincoteague, Sinepuxent, Isle of Wight and Assawoman bays.

Measurements taken over the years by government agencies, independent scientists and volunteers, show that main threat to the coastal bays is the same one as in the Chesapeake. Nutrient pollution, carried into bay waters from farms and subdivisions, can fuel the growth of algae that clouds the waters.

It's "the major threat," says DNR biologist David Goshorn. "There's a gradient, with the northern bays in worse shape than the southern bays."

Computer models trace a little more than half of the nutrient-laden runoff to agriculture, because it is the area's most common land use. Scientists think suburban development contributes pollution, too, but they don't know how much.

At Ocean City, a wide inlet allows the tides to help flush away pollutants from septic tanks and other sources. But to the north, says University of Maryland marine ecologist Donald M. Boesch, the bays suffer from a triple punch: lots of poultry houses and other kinds of farming that produce nutrient-laden runoff; dense suburban development; and only a few, narrow inlets to let cleansing sea water in and polluted bay water out.

In Chincoteague Bay, the water is clear enough for a steady rebound of sea grasses wiped out by diseases decades ago.

But nature seldom paints so simple a picture, and Chincoteague Bay is one of the spots where big mats of algae - commonly considered a sign of pollution - have been reported. "That's really got us scratching our heads," Goshorn said.

University of Rhode Island coastal ecologist Scott Nixon will conduct a study for the National Park Service over the summer to try to figure out whether farm runoff or sewage is fertilizing the "macroalgae" and where the pollution might be coming from.

Over the summer, the DNR plans to send seven crews onto the coastal bays for a weeklong sampling of algae growths at 600 sites. The agency is also convening a summit of scientific experts to try to determine whether the fast-growing algae are crowding out other sea life or providing a haven comparable to the teeming life of a sea-grass bed.

From February to September, DNR biologists are taking weekly water-quality samples at 57 sites along Maryland's coastal bays from Delaware to Virginia. At each location, scientists will measure nutrient levels and look for other warning signs, such as low levels of oxygen in the water that can result from algae blooms and drive away sea life.

Boesch and other scientists say that until there's more information about the state of the coastal bays, it's hard to know how much protection they need.

"There aren't the same resources that there are available for Chesapeake Bay. DNR and the other agencies are really trying to piece together what they can," Boesch says. "We don't have the whole picture for the coastal bays. It's really more of a patchwork quilt."

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