This website uses cookies to ensure you get the best experience while browsing it. By clicking 'Got It' you're accepting these terms.
Most recent
Trending
The best of EcoWatch, right in your inbox. Sign up for our email newsletter!
A study published by the U.S. Geological Survey (USGS) and U.S. Fish and Wildlife Service found large-scale evidence of intersex in smallmouth and largemouth bass in the Northeast U.S., an indicator of endocrine disruption. The study, published in the journal Ecotoxicology and Environmental Safety, looks at 19 U.S. National Wildlife Refuges and is the first reconnaissance survey of this scope. The study found that the prevalence of testicular oocytes across all samples was 85 percent and 27 percent for male small- and largemouth bass, respectively.
Intersex occurs when one sex develops characteristics of the opposite sex. In the case of this study, researchers found testicular oocytes—female eggs found inside male testicles—in male smallmouth and largemouth bass. The study explains: “The presence of oocytes in the testes of male gonochoristic fish has been used as an indicator of estrogenic exposure.”
The source of the estrogen is hard to pinpoint, but pesticides are often cited as a cause given that they widely pollute waterways that fish populate. Those chemicals have properties that disrupt the endocrine system and affect the reproductive system, causing development issues such as testicular oocytes. According to USGS, “Intersex is a global issue, as wild-caught fish affected by endocrine-disrupting chemicals have been found in locations across the world.”
According to the USGS press release for the study, “Estrogenic endocrine-disrupting chemicals are derived from a variety of sources, from natural estrogens to synthetic pharmaceuticals and agrochemicals that enter the waterways. Examples include some types of birth control pills, natural sex hormones in livestock manures, herbicides and pesticides.”
While the study did not look for the sources of endocrine disruption, it did paint a picture of how widespread this abnormality really is, encouraging management actions to combat runoff. “It is not clear what the specific cause of intersex is in these fish,” Luke Iwanowicz, a USGS research biologist and lead author of the paper, said, in their press release. “This study was designed to identify locations that may warrant further investigation. Chemical analyses of fish or water samples at collection sites were not conducted, so we cannot attribute the observation of intersex to specific, known estrogenic endocrine-disrupting chemicals.”
Last summer, research by the USGS showed a strong correlation between the occurrence of intersex characteristics on fish, which have been found in the Chesapeake Bay region and areas of high agricultural use in Pennsylvania. In addition, a recent report by the Pennsylvania Department of Environmental Protection (DEP) found rare malignant tumors on smallmouth bass in the Susquehanna River, a river that flows through the northeast from upstate New York to the Chesapeake Bay. The Susquehanna River is a major source of agricultural runoff containing phosphorous, nitrogen and sediment pollutants, as well as natural animal hormones in manure. Pennsylvania DEP officials are looking to in-depth studies to identify the sources of the endocrine-disrupting compounds and herbicides likely contributing to the tumors.
This is a step that USGS would like to see taken as well. The study states, “A comprehensive re-evaluation that includes chemical analysis and seasonal snapshots of both sites is necessary to identify the likely cause(s) of elevated plasma vitellogenin in these male smallmouth bass.”
In addition to the Pennsylvania DEP study, other scientists are examining fish as a means of gauging water quality and chemical exposure. In 2008, USGS identified ten contaminants, including atrazine, chlorpyrifos and endosulfan, responsible for intersex fish in the Potomac River. Atrazine, one of the most commonly used herbicides in the world, has been shown to affect reproduction of fish at concentrations below U.S. Environmental Protection Agency’s water-quality guidelines. A November study found that commonly-used pesticides can persist in and impact the species of a waterway long after the chemicals are detectable or monitored by regulators.
YOU MIGHT ALSO LIKE
Groundbreaking Study Says Asian Carp Could Make Up One-Third of Lake Erie Biomass
Oppose Welfare Ranching, Not Wolves
Beloved Orca Found Dead Due to Entanglement in Fishing Gear
EcoWatch Daily Newsletter
By Carey Gillam
For the last five years, Chris Stevick has helped his wife Elaine in her battle against a vicious type of cancer that the couple believes was caused by Elaine's repeated use of Monsanto's Roundup herbicide around a California property the couple owned. Now the roles are reversed as Elaine must help Chris face his own cancer.
The last 50 years have been brutal for wildlife. Animals have lost their habitats and seen their numbers plummet. Now a new report from a British conservation group warns that habitat destruction and increased pesticide use has on a trajectory for an "insect apocalypse," which will have dire consequences for humans and all life on Earth, as The Guardian reported.
Sales of electric cars are surging and the world is generating more and more power from renewable sources, but it is not enough to cut greenhouse gas emissions and to stop the global climate crisis, according to a new report from the International Energy Agency (IEA).
By Jake Johnson
A Greenpeace report released Tuesday uses a hypothetical "Smart Supermarket" that has done away with environmentally damaging single-use plastics to outline a possible future in which the world's oceans and communities are free of bags, bottles, packaging and other harmful plastic pollutants.
Trending
By Irene Banos Ruiz
Pediatricians in New Delhi, India, say children's lungs are no longer pink, but black.
Our warming planet is already impacting the health of the world's children and will shape the future of an entire generation if we fail to limit global warming to well below 2 degrees Celsius (35.6°F), the 2019 Lancet Countdown Report on health and climate change shows.
The FBI is looking into how the state of Pennsylvania granted permits for a controversial natural gas pipeline as part of a corruption investigation, the AP reports.
Trending
Three cows who were washed off their North Carolina island by Hurricane Dorian have been found alive after swimming at least two miles, The New York Times reported Wednesday.
The fight between the Standing Rock Sioux and the owners of the Dakota Access Pipeline is back on, as the tribe opposes a pipeline expansion that it argues would increase the risk of an oil spill.