Sprol

In 2006, researchers found that many large and smallmouth bass caught in the Potomac River and its tributaries in the Washington D.C. region were showing signs of “intersex.” Intersex is a condition in which the male fish start growing eggs in their reproductive organs.

As is often the case, the most likely cause is environmental pollutants. In this case, we are talking about pollutants that appear to cause the hormone systems of these fish to go haywire.

The affected bass are naturally born males; however, for some reason these fish begin developing immature eggs. This strange discovery has been found at many spots along the Potomac and was first noted in 2003.

Photo credit: Topato

The precise cause of this unusual physical abnormality is still unknown; however, researchers believe that a class of waterborne contaminants, which ultimately confuse the growth and reproductive systems in affected fish, is the most likely culprit. This type of pollutant is still poorly understood and there are many unanswered questions.

Of course, if the Potomac’s smallmouth and largemouth bass are being so dramatically affected by these contaminates, how are the millions of people who get their tap water from the river being affected?

The jury is still out on that question. In fact, it is not even known if the abnormalities found in the bass are transferable to humans.

There is also no clear-cut evidence that the tap water taken from the Potomac is unsafe. Many also find solace in the belief that humans should be less susceptible to the Potomac’s pollution problems than the fish simply because we are not constantly exposed to the river water.

Additionally, because our bodies dwarf even the biggest largemouth bass, it should require higher doses of any pollutants to cause noticeable health problems, and our hormone systems function differently than that of the fish. But, even with these considerations, the condition of these tainted fish should not be taken lightly.

Research is still being conducted to try to find answers to several illusive questions. Scientists are attempting to determine how the Potomac’s mud and water can affect human cells. Researchers at West Virginia University have been examining cells to see how they react when estrogen or estrogen mimics are present.

No solid conclusions have been discovered in any of these studies.

In 2003, intersex fish were first found in the area of the Potomac River’s South Branch, a tributary over 200 miles upstream from Washington D.C. Increasing numbers of affected smallmouth and largemouth bass were discovered in a section of the upper Potomac near Sharpsburg, Maryland in 2004.

Finally, in the fall of 2005, state and federal researchers fished smallmouth bass from the Shenandoah River in Virginia and in Maryland’s Monocacy River and Conococheague Creek. All three waterways ultimately empty into the Potomac River.

At the point on the Potomac River located in the District, just upstream from the Woodrow Wilson Bridge, there are no smallmouth bass populations. As a result, scientists examined only largemouth bass. The results were astonishing.

At the site in D.C., seven of the 13 male largemouth bass showed some form of unnatural female characteristic. Six of the seven fish even tested positive for a protein necessary for the female body to produce eggs. Three of these seven bass actually contained eggs.

Additionally, greater than 80 percent of all male smallmouth bass caught in the Shenandoah River, Monocacy River and Conococheague Creek were growing eggs. Interestingly, an intersexed bass does not appear different from a normal, healthy fish. The abnormality must be detected using a microscope rather than the naked eye.

All of the combined largemouth and smallmouth bass research seems to indicate that the Potomac River’s watershed has a significant problem with endocrine disruptors. Endocrine disruptors are certain contaminants that interfere with an animal’s natural chemical signaling. In the case of the bass, the pollutants likely sparked some bodily processes that normally only become active in female fish.

Contaminates that impersonate natural hormones have surfaced worldwide over the last decade. They have been charged for problems in animals as diverse as minnows to polar bears to alligators.

Research is still in the very early stages and more knowledge must be uncovered about the effects of endocrine disruptors on both humans and the animal kingdom. Researchers, however, have identified a large array of contaminates that have the potential to affect animals. These include human estrogen found in processed sewage, animal estrogen derived from agricultural farm manure as well as certain pesticides and soap additives.

In reality, the actual problem may be a combination of several toxic substances acting together to cause changes in the bodies of the largemouth and smallmouth bass.

The cause of the endocrine disruptor problem in the Potomac River’s bass population is not the only thing that is unclear. The actual impact on the River’s bass population is also uncertain.

While there have been a number of bad spawning periods over the past 10 years along with several substantial smallmouth bass die-offs in the Shenandoah River in recent years, none of these occurrences has been conclusively linked to the increasing number of intersexed fish.

The mystery of these tainted bass only deepens when we consider how the suspected pollutants affect the health of the human race.

In 1996, as a way to help solve this mystery, the United States Congress directed the United States Environmental Protection Agency (EPA) to begin developing a screening program that will identify which chemicals are endocrine disruptors. However, almost 11 years have passed and the EPA has still not tested a single chemical.

While various environmental groups have accused the EPA of being too sluggish in deriving this program, the Agency says the research has been much more complex than ever anticipated.

If one or more endocrine disruptor pollutants are so seriously affecting so many largemouth and smallmouth bass, it is certainly natural to investigate the condition and safety of the area’s drinking water. At least four drinking-water utility companies, which serve Maryland’s Montgomery and Prince Georges counties, take water directly from the Potomac River.

Because of the vast utilization of the Potomac for drinking water, many environmentalists and local residents worry about the area’s water quality. If the bass are suffering from this bizarre intersex condition, what could possibly be happening within the bodies of humans and other wildlife that use and drink the Potomac River’s water?