Mystery in the Potomac

Scientists still looking for answers to fish kills, intersex fish

Scientists still looking for answers to fish kills, intersex fish

January 21, 2007|by JULIE E. GREENE

Two years ago when Sharpsburg resident Dave Lemarie learned that male fish containing eggs had been discovered in the Potomac River basin, he and his wife stopped drinking tap water.

Lemarie, a biologist who is not studying the river - reasoned that if the water did that to the fish, it could not be good for people.

Since 2002 there have been several fish kills and a high percentage of tested smallmouth bass found to be intersex - exhibiting characteristics of the opposite sex, said Vicki Blazer, a fish pathologist with the U.S. Geological Survey at the Leetown Science Center in Kearneysville, W.Va.

A cause hasn't been found for either, and while Blazer thinks the two are linked, there's no proof of that yet, either.


So should people drink water or eat fish from the river?

Those questions defy simple yes or no answers, said Curtis Dalpra, who is not a scientist but a spokesman for the Interstate Commission on the Potomac River Basin. The nonprofit commission is a nonregulatory group that works with watershed states to help with research and planning. The commission works to protect the river basin and associated land resources.

Experts don't know what substance - or substances - is causing the fish problems, so they can't determine its presence in drinking water.

"Until we understand the problem we're facing, it's difficult to confront the problem," Dalpra said.

The Environmental Protection Agency wants to reassure the public that drinking water treated by public water systems is safe, stated spokeswoman Suzanne Ackerman in an e-mail to The Herald-Mail.

Drinking water goes through extensive treatment to remove many chemicals, Ackerman said.

However, there aren't measurement standards for every chemical, Dalpra said. And with new substances being produced, it's daunting for government agencies like the EPA keep up with them all, he said.

Enough research hasn't been done and in some cases techniques haven't been developed to measure low quantities of chemicals in the fish and river, Blazer said.

Testing for microcontaminants is expensive, said George Harman, program manager for Environmental Assessments and Standards with the Maryland Department of the Environment (MDE).

No individual government agency has the resources to do as much testing as some scientists would like to do, but as a team they are pursuing testing of as many chemicals as needed, Harman said.

While no cause has been determined for intersex conditions found in portions of the Potomac River basin such as the Conococheague River and Antietam Creek, that condition has internationally been associated with human wastewater effluence, agricultural runoff and paper and pulp mills, Blazer said.

The intersex conditions and fish kills could stem from a combination of chemicals or contaminants affecting the fish or their environment, including the sediment in which smallmouth bass lay their eggs, she said.

Blazer hopes to get sediment samples at smallmouth bass nesting sites as well as nesting males for study this year.

Some of the contaminants found in the fish and water so far include chemicals found in fragrances that are known to disrupt hormone function, Blazer said.

Other contaminants found in the water that could be stressing fish include pesticides and antibacterial compounds from soaps and detergents.

"It's important to realize that as a culture we are constantly putting all kinds of synthetic chemicals into the environment and some of them are likely to have an effect," Dalpra said.

Other factors that can stress fish are water that is too warm, a high pH content in the river and heavy rains that increase agricultural runoff, Blazer said.

Experimental work with water at other locations - not the Potomac basin - has found that estrogen and estrogenic compounds such as some pesticides and pharmaceuticals can affect fish's immune response, allowing bacterial and parasite levels to increase, Blazer says.

That could be one of many stressors contributing to fish kills, Blazer said.

But ultimately no one knows the cause of these problems.

There has been a lot of work to suggest that endocrine or hormone disrupting chemicals can affect fish, said Ackerman with the EPA.

The EPA is studying and funding studies analyzing hormone disruptors and ways to remove them from the river, Ackerman said.

Any hormone disruptors not removed during the treatment process for drinking water would be trace amounts, she said.

Without enough evidence about hormone disruptors and what's going wrong with the fish in the Potomac and its tributaries, MDE can't justify making any recommendation regarding eating fish from those waters, Harman said.

"I'm not saying it's OK to eat (these) fish. I'm not saying it's not OK to eat (these) fish," Harman said.

MDE does issue fish consumption advisories, but those are in regard to mercury and polychlorinated biphenyls (PCBs) and the potential hazards of eating a lot of those fish every year for 30 years, he said.

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