Tiny shrimp species found in Pa. river

August 24, 2006

(AP) -- Biologists have discovered a species of shrimp in the Monongahela River for the first time, a discovery the scientists say is evidence that the river's water quality is improving.

Known as glass or grass shrimp, the tiny, translucent creatures are native to the Mississippi River basin and prefer to live in river-bottom vegetation. But Palaemonetes kadiakensis, as they are referred to by scientists, has never been found in the Monongahela, said David Argent, a California University of Pennsylvania biologist.

"This is probably the last thing we would ever had expected to find," Argent said. "They haven't been found this far east in fresh water as far as we can tell."

The Pittsburgh Post-Gazette first reported the find Wednesday.

Eleven glass shrimp, most of them carrying eggs, were found when Argent and William Kimmel, another California University biology professor, trawled a 40-mile stretch of the river from Fayette City to the West Virginia border. Argent said he doesn't believe bottom trawlers have ever been used on the Monongahela.

"This population just sort of turned up," said Charles Bier, senior director of conservation science at the Western Pennsylvania Conservancy. "It does indicate that the Monongahela is one of the streams in the area that is on the comeback."

The Monongahela has not always had a reputation for pristine waters.

The river was left almost devoid of life by acid mine drainage and pollution from the steel mills and factories that dominated its banks for much of the last century.

It was recorded as having a pH of 3.8 in the 1950s, Argent said. Normal pH is 7.0.

"That's not as strong as battery acid, but it might as well be," he said. "Historic data from the '50s and '60s suggests that there wasn't much in terms of aquatic life. Now we're picking up all sorts of new things."

Glass shrimp were common in Lake Erie in the early 1970s but disappeared until the mid-1990s, said Ed Masteller, an emeritus professor of biology at Penn State Erie. They likely returned because of improving oxygen levels on the lake's bottom, he said.

Experts attribute the Monongahela's recovery to the closure of most steel mills, the Clean Water Act and other environmental protection measures.

More research would be needed to determine the origins of the Monongahela's glass shrimp, Argent said. The crustaceans may have hitched a ride in the ballast water of a boat, been dumped into the river from an aquarium or migrated up the river on their own, he said.

"Unfortunately they can't speak, so they can't tell us where they came from," he quipped.

Other wildlife probably eat the shrimp, but they may be too small for convenient human consumption.

"You'd probably need a few thousand to make a meal," Argent said. "We could drag the entire river and catch dinner."

By MICHAEL COWDEN, Associated Press Writer
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