We All Live Downstream

Water flows downhill and with it comes pollution that affects life in and along the rivers and the ocean. Scientists analyze mountain fish and coastal blue crabs to learn what's flowing downstream in North Carolina's waterways.

BOONE — There’s a lot of water flowing throughout North Carolina.

The Upper South Fork of the New River, which flows through the northwest corner of North Carolina and into Virginia and passes through Boone and the Appalachian State University campus, is just one example.

The U.S. Environmental Protection Agency (EPA) lists roughly 38,200 miles of streams and rivers in the state. Some are large, some are small, and in general, the agency lists the water quality as fairly good. That’s thanks, in part, to the more than 150 wastewater treatment plants around the state, according to the North Carolina Department of Environment and Natural Resources. The facilities work hard to remove nutrients and bacteria from the water they discharge back into the state’s waterways. 

But there is a growing concern among scientists about the effects of the mix of personal care products and pharmaceuticals that are finding their way into the water.

That’s why Dr. Shea Tuberty, Associate Professor of Invertebrate Physiology at Appalachian State University, is wading through the fast moving water of the Upper South Fork of the New River with two graduate students.

He’s been studying this stretch of the fast moving river, in the middle of Boone, for the past 10 years and has tracked the increase in the amount of chemicals in the water.

“We’re interested in what are the effects of everything we put into our waste stream, from our homes, businesses, the university and what happens to those compounds in the sewage effluents,” explains Dr. Tuberty. “And then once those compounds get from the effluent into the river, we want to know what happens to the rivers and the myriad compounds that end up in that water.” Effluent is liquid waste or sewage discharged into a river or the sea.

To be clear, Dr. Tuberty and his students aren’t just wading through the water. They are electro-fishing. One of the students carries a large battery pack on his back and holds a metal pole in the water. There’s a wire that connects the pole to the pack. Hitting a button sends a small electrical charge into the water.

The electrical shock stuns fish so scientists can study and release them without harming the fish. While all of fish are counted, examined, and released, particular attention is paid to the male fish. That’s because scientists are finding evidence of intersex fish. That means male fish are turning into females. Scientists are asking if that’s because of the increase in estrogenic compounds being sent into toilets, sinks and showers.

“Specifically we are looking for effects that mimic estrogens, so we’re focusing on male fish in an attempt to measure what percent of the population is feminized by this soup of chemicals in the effluent, many of which are estrogenic," says Dr. Tuberty, as he shows off a male blue headed chub that he snagged with a net. “When I say estrogenic, that’s a term that means they bind to estrogen receptors in the genes and mimic the effects of estrogen.”

Once the fish are caught, there are multiple studies that can be performed to determine estrogenic effects. Researchers can draw blood and look for egg proteins. The fish can also be sacrificed so scientists can dissect out the testes to see if eggs may be developing in the testes, which is an indication the fish is becoming intersexed. Researchers can also study the concentration of sex hormones.

Estrogen is a hormone that is important for sexual and reproductive development in females. While wastewater treatment plants successfully remove most pollutants, including nutrients and bacteria, from the water they discharge back into the rivers and streams, some estrogenic compounds are not removed. The amount of estrogenic compounds in the water is small and the water is generally considered safe for humans. The fish are safe to eat as well. But for the fish, finding even trace amounts of estrogen can be a long-term concern.

“The amount of estrogenic compounds in the water is more environmentally relevant for the fish estrogen receptor than the human because fish are more sensitive,” says Brandon Tate, one of the graduate students from Appalachian State University who is working on the project. “Fish have three estrogen receptors while humans have two, which makes the fish more sensitive.”

So why is this a concern, if the fish are still safe to eat?

It’s because if the number of transforming fish grows, it could affect the fish population in the river. There simply wouldn’t be enough male fish to reproduce.

“If you see less populations of fish there’s probably less reproduction going on, and that could be caused by estrogenic compounds changing the fish,” says Will Jones, a senior studying ecology at Appalachian State University.

Scientists are working to pin down the source of the estrogenic compounds, however Dr. Tuberty admits it’s possible there isn’t just one source. There have been dozens of studies through the years that show many compounds interact with estrogen receptors. In addition, there are hundreds of molecules that are used every day that can be estrogenic. The bottom line, what appears to be affecting the fish is more likely what researchers call the “soup” effect. In other words, the concentrations of many compounds acting all together are producing the estrogenic effects.

And it turns out the Upper Fork of the New River is not the only waterway in the state that is seeing estrogenic effects on fish. The Upper Fork of the New River Basin, which runs through North Carolina and Virginia, drains roughly 752 square miles. It’s one of nine river basins in North Carolina, all of which eventually flow into the sea.

And since everything in the rivers flows downstream into the sea, it is not surprising that scientists are finding blue crabs, which live along the coast, also showing evidence of the effects of estrogenic compounds.

“The kind of stuff we’re looking for in these crabs is going to indicate water quality, and health issues that could matter in the future,” says Andrew Goff, a graduate student in marine biology at The University of North Carolina Wilmington, lowering a crab pot into the Masonboro Sound, just off the coast near Wilmington. “And if we keep pouring stuff into waterways the way we are, it could affect us," Goff adds.

The Masonboro Sound is one of four sampling locations for a study of blue crabs, a study which is being partly funded by North Carolina Sea Grant. The sound is a tidal estuary, which mixes salt water from the sea and fresh water from the land. It turns out that crabs, especially blue crabs, are good indicators of water quality because they filter so much water through their systems. In recent years, the crab population has been declining. Researchers want to see what kind of hormonal response or any kind of ecotoxicological effects the crabs might be experiencing.

The crabs are analyzed in a lab at the University of North Carolina Wilmington, where scientists collect the hepatopancreas, eggs and ovaries to examine if there are any physical changes in the organs. Scientists also study the chemical composition of the eggs. If the crab is male, scientists examine the vas deferens to look at RNA expression.

In addition, a tissue sample is taken from the reproductive organs to study the RNA, or the ribonucleic acid. RNA is a molecule that carries genetic information and guides the production of proteins, which regulate the work of cells. Scientists want to see if the crab RNA carries the code for the gene called vitellogenin. It’s a protein found in the egg yolk that should only be found in females, not in males. 

“Female crabs should express this gene because it’s the gene that gets translated into the protein that produces the egg yolk for all those wonderful eggs the female is going to produce. “The jury is still out on this but some studies have shown that male crabs exposed to chemicals that disrupt endocrine function produce this gene in the hepatopancreas. They shouldn’t be but they do,” says Dr. Susanne Brander, Assistant Professor of Biology and Marine Biology at UNC Wilmington.

Just how that happens is unclear, but scientists want to study and compare crabs from the four sample locations to see if crabs from more polluted sites are producing the gene while crabs from more pristine sites do not.

There are still many questions to answer, but researchers involved in both projects say if nothing else is learned in the immediate future, residents should understand that one of the easiest way to protect the state’s waterways is to properly dispose of pharmaceuticals at medicine collection stations and not by flushing medicines down the drain.

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