sex changes near the farm
Brent Finnegan -- March 5th, 2008
Biologists have long known that high levels of estrogen compounds in the water can cause male fish to produce eggs. It happens in waterways in densely populated metropolitan areas, where pharmaceutical chemicals make their way through humans, into the sewers, and ultimately, into the fish.
But a recent study of fish in the Chesapeake watershed by U.S. Geological Survey (USGS) found that these “sex changes” are actually happening more frequently in agricultural regions around Shenandoah Valley.
“We collected smallmouth bass from the Shenandoah, the South Branch of the Potomac, and out of the basin for comparison,” said USGS scientist Vicki Blazer, who led the study. “The fish from the sites with the highest human population density and the most farming had the highest incidences of intersex,” said Blazer. “On the Shenandoah, rates of intersex were highest, ranging from 80-100 percent intersex.”
Yes, you read that correctly. It’s not a typo. 80-100 percent of the male fish around here have eggs.
From the Chesapeake Bay Journal:
Intersex is thought to be caused by any of a number of chemicals—from pesticides and other compounds used in agriculture to hormones from birth control pills and other pharmaceuticals—which can affect the reproductive system.
The paper said a number of chemicals known to have estrogenic properties were also found in the water where smallmouth bass were collected, including several found in herbicides and pesticides used in agriculture.
But the paper cautioned that it’s “unlikely that only one contaminant or source is responsible” for intersex. Rather, it suggested, the condition is likely caused by exposures to multiple contaminants.
USGS found that the occurrence of eggs in male fish increases in the spring, before and during spawning season.
But the discovery of male eggs was an accident; that’s not what they were looking for. The researchers were trying to figure out why large numbers of dead fish have been washing up on Shenandoah riverbanks in recent years, covered in lesions. Past studies of local fish kills have been inconclusive, but point toward a combination of urban/suburban, agricultural, and industrial waste as the overall cause.
(via the Shenandoah Riverkeeper blog)
uh oh….A episode of the Simpsons comes to mind….
Yes, if fish are the proverbial “canary in the coal mine,” we’re all in a lot of trouble.
kudos on finding that picture….that’s exactly what I was thinking of….
Yep, it is scary. We just posted another article about medications getting into the water on the Pure Water Forum’s Fish Kill blog:
http://www.purewaterforum.org/fishkill/
Hey Renee, thanks for all that information on your website. I wonder if we can figure out something to help the banks of the South Fork in the park in Grottoes. I like to fish there but the are to the right of the “ramp” is so bare…I know it is hard to get grass to grow where there is heavy foot traffic, but I don’t know what else would work. Please feel free to keep me up to date with any projects you may need help with.
A good general descriptor for the family of contaminants capable of doing this sort of mutation would be “endocrine disruptors”. This includes a range of complex polymers like Bisphenol A, Phthalates, and Polybrominated diphenyl ethers – all common ingredients in our manufactured goods, and all known to be capable of disrupting the hormones that control biological systems.
My point being that this kind of thing could be tied to way more than farm residues. Plasticizers, fire-retardents, flooring, as well as burn residues (furans, phenols, PAH, PCB’s). The US EPA had a large research program on endocrine disrupting chemicals (EDC) prior to the Bush Administration.
Thanks for the offer, Frank. The person to contact about helping the Pure Water Forum is Bruce Lundeen (I’m just the webmaster for the Forum). You can fill out the email contact form on the website to get in touch with him.
http://www.purewaterforum.org/?page_id=14
INteresting water issues.
Thanks for the interest H’Burg.
Bubby, what was most interesting about the USGS intersex study is that they found highest levels of intersex in areas with very low human populations and development (which would theoretically be responsible for the family of contaminants you listed)
There was a clear and strong correlation between agricultural intensity and both severity and prevalence of intersex. For example; the Cowpasture River, by most measurements a pristine ridge and valley stream with very few humans but quite a bit of agriculture, had THE VERY HIGHEST intersex levels with 100% of the fish and the highest intersex rating of 2.1. The Upper Conococheague in Maryland scored about the same.
Compare that to the Shenandoah which had 80%-100% intersex a rating more like 1.2-1.7, and those were in areas downriver of both quite a few sewer treatment facilities and industrial discharges. Maybe our sewerage is a cure for intersex !(just kidding).
Just didn’t want that link to get lost.
Jeff Kelble- Shenandoah Riverkeeper
Jeff, Thanks for that clarification. The strong correlation to agriculture land use patterns implicates an influence by EDC’s like herbicides (atrazine), and insecticides (dieldrin, heptachlor, methoxychlor, lindane, endosulfan). I’m guessing that alot of valley farmers use atrazine in their no-till methods and it has been shown to cause these sort of reproductive-system mutations. Although the literature says atrazine is degraded by bacteria, that supposes that the environment for degradation is available, or uniform…a big assumption.
As a marine biologist, I was a co-author on one of the most comprehensive and cited research studies conducted on food fishes in the Caribbean. One thing we concentrated on is the effects of environmental stress (over-fishing, water quality, native myths/beliefs & diminished bredding sites) on reproduction and sexual maturity. We understood that many species of fish do indeed change their sex in response to environmental stress and species preservation.
One day, I pray, the people and politicians will listen to the experts who care about the world they live in, rather than the companies that exploit it.
The DNR ran a story on this today:
In a related article, this shows some more disturbing trends towards drinking water pollution.
http://news.yahoo.com/s/ap/20080310/ap_on_re_us/pharmawater_i
CNN ran this article today about presecription meds in our water:
“Also, pharmaceuticals in waterways are damaging wildlife across the nation and around the globe, research shows. Notably, male fish are being feminized, creating egg yolk proteins, a process usually restricted to females. Pharmaceuticals also are affecting sentinel species at the foundation of the pyramid of life — such as earthworms in the wild and zooplankton in the laboratory, studies show.”