Photo by Dan Neuland The upper Potomac River is beautiful; however, environmentalists are concerned over recent studies that cannot pinpoint the cause of abnormalities found the bass population.

Scientists from the U.S. Geological Studies and the U.S. Fish & Wildlife Service have been working together to learn more about these problems. One of the major findings was the presence of intersexual characteristics in smallmouth and largemouth bass in the Potomac River and its tributaries.

In April, the USFS released the final report of a six-year study, titled "Assessment of Endocrine Disruption in Smallmouth Bass and Largemouth Bass in the Potomac River Watershed." The study found a substantial proportion of abnormal fish from sites on the Potomac and Monocacy rivers and the Conococheague Creek in Washington County. Some sites were reported to have between 82 and 100 percent of the male fish with some female characteristics.

The issue

The term intersex, or intersexual characteristics, describes a range of abnormalities in which both male and female characteristics are present in the same fish. Intersexual characteristics are most commonly described as the presence of female germ cells, which are the precursor to mature eggs, in a male reproductive organ.

The occurrence of intersex fish has been related to chemicals, often termed endocrine disruptors, that affect the reproductive system. Endocrine disruptors are chemicals that interfere with the natural balance of hormones that regulate development, reproduction, metabolism, behavior and the internal state of living organisms. Occasionally these abnormalities can be noted externally but most often the main reproductive organs must be examined under a microscope for diagnosis of intersexual characteristics. The presence of this abnormality or intersexual characteristic has been used as an indicator of exposure to estrogenic chemicals and has been documented in a variety of wild fish species in a number of rivers and estuaries around the U.S. and several other countries.

Potential causes

Researchers believe that a mixture of pollutants coming from the discharge of sewage treatment plants and farm run-off into the waterways may be the cause. Current research on intersexual characteristics has related numerous chemicals to reproductive effects in fish. These chemicals, often termed endocrine disruptors, include previously banned chemicals, such as DDT and chlordane, natural and anthropogenic hormones, herbicides, fungicides, industrial chemicals and an emerging group of chemicals including personal care products and pharmaceuticals that may act as endocrine disruptors in fish as well as other organisms.

Wastewater treatment plants are only one potential source of chemicals that may adversely affect general and reproductive health of fishes. Run-off from agricultural land has been shown to contain hormones and pharmaceutical chemicals. Additionally, pesticides and herbicides applied on agricultural, public and residential lands are transported to aquatic ecosystems during rain events.

Unfortunately the research to date has been largely inconclusive. Water tests on sites in the upper Potomac have detected low levels of known endocrine disruptors. However, none of these chemicals have been pinpointed as a cause for the intersex condition, and the problem is more likely a combination of several factors. Not surprisingly, the fish from the sites with the highest human population density and the most farming had the highest incidences of intersex.

Although the risk to humans from fish with intersexual characteristics is currently unknown, the much bigger issue is the quality of the water that the Potomac provides to the millions of people who take their drinking water from it. The river supplies drinking water for Frederick , Montgomery and Prince George's counties in Maryland, Fairfax County in Virginia and the District of Columbia.

Ed Merrifield, executive director of the environmental group called Potomac Riverkeeper, believes the whole issue of fish abnormalities comes down to water quality. In a recent phone conversation, Merrifield highlighted the need to increase our water quality standards. "The health of our rivers and streams needs to be everyone's concern É there are chemicals in our drinking water in small amounts and we can no longer say the solution is dilution," said Merrifield.

He also pointed out that, currently, the water in the Potomac meets or exceeds all EPA requirements.

John Brognard is the conservation representative for the Mid-Atlantic Council of the Federation of Fly Fishers. Brognard believes that the smallmouth bass of the Potomac River watershed are an early warning signal and compares the fish to the birds used by miners for safety. "Years ago mineworkers would take a caged canary into the mine with them É if the canary passed out, the miners knew they were in danger of a poisonous gas and would leave the mine immediately," Brognard said. "We all need to be concerned about the quality of our drinking water and the future effects on our children and grandchildren."

Brognard encourages everyone to support efforts to prevent these dangerous substances from getting into our streams and rivers.

Leopoldo Miranda-Castro, supervisor of the U.S. Fish & Wildlife Service Chesapeake Bay field office, will be the guest speaker at the next Potomac Valley Fly Fishers meeting on Nov. 10. The meeting begins at 7 p.m. and will be held on the Maryland School for the Deaf campus in Frederick . Miranda-Castro will discuss the final report that his office prepared on endocrine disruption in the Potomac River watershed. The public is encouraged to attend.

There are many grassroots organizations in our area that are working to clean up our streams and protect our waterways. To learn more about the Potomac River and the other designated endangered fisheries, visit these websites:

n Federation of Fly Fishers

www.fedflyfishers.org

n Potomac Valley Fly Fishers www.pvflyfish.org

n Potomac River Keeper

www.potomacriverkeeper.org

Contact Dan Neuland at steeliedan@xecu.net.