Killer disease, helpful billboards Protection: While the source of a devastating oyster disease remains elusive, bay watchers can be gratified that soon billboards will encourage the public to protect the watershed.

On the Bay

November 01, 1996|By Tom Horton | Tom Horton,SUN STAFF

THIS WEEK: Origins of a bay killer; billboards an environmentalist can love; an update on reviving sturgeon; and the straight poop on farm animals and the bay.

The source of MSX is still a mystery

For nearly 40 years it has been a mystery: From where did MSX, the disease that began devastating Chesapeake oysters around 1959, come?

It has waxed and waned since then, retreating in rainy years when the bay is fresher, advancing during droughts when the estuary salts up.

Along with Dermo, another disease, MSX continues to frustrate attempts to restore the shellfish that acted as a vital ecological filter cleansing bay waters, and whose harvest once employed a fifth of everyone fishing in America.

Dermo appears to be a natural disease of Crassostrea virginica, our eastern oyster, one it probably evolved with, but MSX was something never before seen.

Was it a spontaneous mutation of some less harmful parasite? Was it introduced in bilge water pumped from foreign tankers in Delaware Bay, where it first was identified in 1957?

New evidence from the Virginia Institute of Marine Science strongly suggests MSX came from the Asian oyster, Crassostrea gigas.

Gene Burreson, an institute scientist, has compared the DNA sequences of a gene from MSX and from a common gigas parasite, and found them virtually identical.

Gigas oysters were introduced in many places around the East Coast during the 1950s and before. The oysters, which flourish on the West Coast, never survived, but apparently the parasite, rarely fatal to gigas, flourished.

Burreson's discovery provides no easy cure but may open the way for geneticists to someday engineer gigas's resistance to MSX into our eastern oysters.

Ocean City-area drivers to get a bay message

Fundamental to sustaining a healthy Chesapeake Bay is connecting its water quality to the activity of some 15 million of us -- in six states -- on its "watershed," the lands that drain into the Bay.

Beginning this month, motorists going to and from Ocean City will get this message from four hand-painted billboards erected on U.S. 50 and Route 90.

Featuring a crab, a rockfish and a great blue heron in the marsh, the signs will notify people they are entering/leaving the Chesapeake's watershed, which runs, east to west, from Atlantic beaches into West Virginia and Altoona, Pa. North to south, it spans Cooperstown, N.Y., to Norfolk, Va.

Similar signs, with different symbols, are planned for strategic points in Pennsylvania and Virginia -- with Maryland, the principal watershed states -- and eventually for Delaware, New York and West Virginia.

Perhaps only the ubiquitous great blue heron might appropriately appear on the watershed markers in all six states.

The signs are a product of the Chesapeake Bay Commission, the tri-state, legislative advisory group formed in 1980 to help guide bay policies for Virginia, Pennsylvania and Maryland.

Next, we need maps of the watershed in every school in all six states.

Signs are "good" in effort to restore sturgeon to bay

On the Nanticoke River between Cambridge and Salisbury, two sturgeon released in July have been recaptured by scientists eager to see whether attempts to restore this ancient, vanished species to the bay can work.

"The signs were good," said Jill Stevenson, a graduate research assistant at the University of Maryland's Chesapeake Biological Laboratory at Solomons. "They were full of amphipods [shrimplike, bottom-dwelling crustaceans], so they're finding food, feeding and growing."

Stevenson and her boss, David Secor, along with state and federal biologists, released some 3,000 sturgeon at Vienna and Sharptown, ranging in length from a couple of inches to more than six inches.

Several decades from now, survivors could measure 10 feet or more. Once common enough to support a caviar industry, Atlantic sturgeon are virtually gone from the bay. The released fish came from a Hudson River female in a federal fish hatchery.

The two fish recaptured are all that have been found of the July stocking experiment. Many of the smaller ones "probably are in catfish bellies," Stevenson said.

Another 11 young sturgeon, equipped with transmitters that will allow them to be tracked for the next year, recently were released in the Nanticoke. Eight of these seem to be residing happily near the river's mouth.

Mill wins award for cutting manure phosphorus content

The commission recently gave a novel bay-saving award to Wenger's Feed Mill of Lancaster County, Pa.

Wenger's has begun supplementing the feed it sells for millions of laying hens with an enzyme that allows poultry and swine to more efficiently extract the nutrient phosphorus from their feed. The bottom line is manure that contains 25 per cent less phosphorus, which is a bigger deal than those uninitiated in the bay's problems might realize.

Animal manures are produced in the bay watershed by the tens of millions of tons per year. They are a significant source of the nutrients, nitrogen and phosphorus, that are overfertilizing bay waters. They kill underwater grasses and rob oxygen from aquatic life.

Feed additives like the one Wenger's is pioneering, plus manipulation of farm animal diets to reduce nitrogen in manure, appear to have real potential for attacking this fundamental pollution problem at the source.

Pub Date: 11/01/96

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