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Entries in herbicides (7)

Thursday
May182017

Milfoil Hybrid Could Cause Even More Problems for Northern Fisheries

Management of problematic aquatic vegetation could get even more difficult, especially in northern bass waters. Recent findings in Minnesota's Minnetonka and Christmas lakes lead researchers to theorize that a milfoil hybrid could be more invasive and tougher to control than the Eurasian variety.

The hybrid is a cross between Eurasian and northern watermilfoil, a native plant.

Using cutting-edge genetic screening techniques, scientists from the University of Minnesota and Montana State discovered that the hybrid was more prevalent in areas treated with herbicides than those with little management. The Minnehaha Creek Watershed District (MCWD) said that herbicides might actually promote hybrid growth "and some hybrids may show greater tolerance to treatment."

Additionally, MCWD's Eric Fieldseth said, "As a pilot study, this research gets the ball rolling on understanding hybrid watermilfoil, its impact, and how it can better be controlled. These findings are an important first step toward developing more effective milfoil management strategies."

Researchers also found multiple, genetically distinct genotypes of invasive, hybrid, and native watermilfoil. That underscores the need for understanding the genetic makeup of invasive plants in a fishery before devising a plan to manage them and then following up with more genetic screening to guide future management, MCWD explained.

"With this much diversity in the population, a successful milfoil management strategy may not be a 'one size fits all' approach," added, Ryan Thum, professor of plant sciences and plant pathology at Montana State.

"We're looking forward to seeing how these results compare with what's happening in other parts of the region," he said. "This research could have broad implications for managing milfoil in lakes throughout the Upper Midwest and beyond."

Sunday
Apr242016

Intersex Male Bass Found in Lake Champlain Tributary

Sixty to 75 percent of male smallmouth bass in a tributary of Lake Champlain are "intersex," meaning they bear eggs.

The watershed for the Missisquoi River already has been a cause for concern because of runoff agricultural pollution that feeds blue-green algae blooms in the lake.

"The alarm to me is that these chemicals are present. They're in our water. They're in our food. We're exposing ourselves to them. To me, that's the alarm," said Vicki Blazer, a U.S. Geological Survey scientist and one of the report's authors.

She added that humans aren't exposed in the same way that fish are, since they aren't constantly in the water and our drinking water is treated. "But that doesn't mean we're not exposing ourselves to many of the same chemicals."

James Ehlers, executive director of Lake Champlain International, added, "I think they're basically Franken-fish. It's a canary in a coal mine, except it's bass in a river, and there's something monstrously out of balance in the natural system."

The herbicide atrazine could be a possible cause, as could the hormones contained in livestock wastes from factory farms.

"The big thing to me is that we don't truly understand the mix of things fish and other organisms are exposed to," Blazer said.

Intersex bass also have been found in the rivers and streams near and in wildlife refuges in the Northeast, as well as the Chesapeake Bay watershed.

Friday
Feb262016

Herbicides, Parasites Likely Causes for Susquehanna Decline

Endocrine-disrupting compounds and herbicides, as well as pathogens and parasites, are the most likely causes for the decline of the Susquehanna River's world-class smallmouth fishery, according to results of a multi-year study by the Pennsylvania Department of Environmental Protection (DEP) and other agencies.

"We appreciate the assistance of the U.S. EPA (Environmental Protection Agency) and our other partners in the evaluation of many possible stressors to the smallmouth bass population . . . ," said John Arway, executive director of the Pennsylvania Fish and Boat Commission (FBC).

"The health of the smallmouth bass in the Susquehanna River continues to be compromised and this analysis rules out certain causes, prioritizes other uncertain causes for further study, and, most importantly, identifies likely causes which can be targeted for action."

TO FBC's credit, it has been sounding the alarm about fish with lesions and sores, as well as declining numbers, for years, as well as lobbied DEP to categorize the lower portion of the river as "impaired."  That designation would allow for a comprehensive plan to be developed to address the problem.

Until the release of this study, though, DEP countered that it makes recommendations based on water quality, not species health, and refused to recommend that the Susquehanna be placed on the EPA's impaired waters list. Anglers and groups such as the Chesapeake Bay Foundation (CBF) hope that these findings will help the river get the help it needs.

"The time to start to remedy the sick Susquehanna River and save a world-class smallmouth fishery is now," said CBF's Harry Campbell. "An impairment declaration will start the healing process so that the waterway that millions of Pennsylvanians depend upon, and provides half of the freshwater to the Chesapeake Bay, can benefit from an unwavering level of restoration, resource investment, and pollution study."

Scientists now view temperature, dissolved oxygen, algal and bacterial toxins, and young-of-the-year food quality and habitat as "uncertain causes."  Meanwhile, "unlikely causes" include high flows, ammonia, and toxic chemicals such as pesticides, PCBs, and metals.

Monday
Aug042014

Scientists Find More Mutated Intersex Fish in Nation's Waters

All scientists have to do is search new waters, it seems, and the mystery of mutated intersex fish grows more disturbing.

Most recently, they’ve found male smallmouth bass carrying eggs in Pennsylvania’s Susquehanna, Delaware, and Ohio river basins, according to a new report by the U.S. Geological Survey. Male fish at every site sampled had immature eggs in their testes, with the highest percentage in the Susquehanna. Previously in the Chesapeake Bay drainage, research revealed evidence of the effects of endocrine-disrupting chemicals in the Potomac.

Vicki Blazer, lead author of the study, said that the pollutants affecting bass, as well as white suckers, “are most likely complex mixtures form both agriculture sources, such as animal wastes, pesticides and herbicides, and human sources from wastewater treatment plan effluent and other sewage discharges.”

"The prevalence and severity of the immature eggs in smallmouth bass corresponded with the percent of agricultural land use in the watershed above the collection sites," the scientist said. "Chemical compounds associated with estrogenic endocrine disruption, in particular estrone, a natural estrogen, were also associated with the extent and severity of these effects in bass."

Meanwhile, a toxicologist with the U.S. Environmental Protect Agency office in Denver reported that her research on fathead minnows is suggesting that “a very potent synthetic female hormone . . . can wipe out fish populations over several generations, and it’s the male fish that are most affected.”

Previously, Kristen Keteles added, studies had shown that male fish below wastewater treatment plants can lose masculine characteristics and become indistinguishable from females when exposed to estrogen and other endocrine disruptors.

“Our new study found that a potent form of female hormone estrogen used in prescription drugs not only causes the males to look female; it also appears to be toxic to male fish and these effects may impact future generations of fish.”

Fish A is a normal male fathead minnow. Fish C is a normal female. B is a male that was exposed to female hormones in prescription drugs and looks more like a female. Photo by Adam Schwindt

These disturbing discoveries regarding fish, which could portend similar problems for other species, began to emerge in the late 1970s, with anglers fishing wastewater lagoons in Great Britain, according to Whitney Jacobs, a former Conservation Associate at B.A.S.S. who researched the effects of environmental estrogens on male fish while doing graduate work in fisheries at the University of Georgia.

But the first reports of intersex was not documented in scientific literature until 1994 and the first major national assessment of the problem was not published until 2009,  she added.

“Widespread occurrence of intersex in black basses (Micropterus spp.) from U.S. rivers, 1995-2004” revealed intersex in 3 percent of fish collected and in 4 of 16 species--- largemouth bass, smallmouth bass, common carp, and channel catfish.

“However, it was most prevalent in largemouth and smallmouth bass,” Jacobs said. “The study also found the greatest incidence of the condition in the southeastern U.S.”

More recently, a 2014 report from scientists at the University of Georgia revealed these mutations aren’t confined to rivers. In “Survey of Intersex Largemouth Bass from Impoundments in Georgia USA,” they said that 48 percent of male largemouth bass collected from 11 reservoirs without direct municipal or agricultural wastewater inputs were intersex. Additionally, they found the condition in nine of the fisheries.

“The high incidence of intersex males in small impoundments demonstrates the condition is not confined to rivers and suggests that factors other than those previously associated with intersex (i.e., municipal wastewater) may be involved,” the researchers concluded.

Scientists hope that future research will reveal those additional factors. Meanwhile, they believe that fish that live downstream of wastewater treatment plants are most at risk, because of chemicals that can’t be filtered out of discharges.

“Humans excrete hormones and medications, which often end up in our rivers and streams from sewage,” said Keteles, adding that flushing medications also contributes to the problem.

“The water is treated, but many hormones and pharmaceuticals are not completely removed by wastewater treatment plants,” she said.

“My team is trying to determine what this means for fish, and ultimately for people, too.”

How to dispose of medicines properly

(This article appeared originally in B.A.S.S. Times.)

Tuesday
Sep172013

Duke Energy Develops Effective Strategy for Hydrilla Control

For years, resource managers have struggled to find a cost-effective and efficient way to control hydrilla. Mass application of herbicide can be cost prohibitive, as well as unpopular with anglers, environmentalists, and lakefront property owners. Grass carp, meanwhile, need years to bring the fast-growing exotic plant under control, unless they are stocked at exceptionally high rates, which also can be unpopular and expensive.

But Duke Energy Corporation has developed an effective management strategy for five of its Piedmont reservoirs that incorporates moderate use of both herbicides and carp. This reduces cost, as well as minimizes the likelihood of the adverse effects on fisheries that often accompany heavy stocking of grass carp.

This one-two punch, however, is not the sole reason for success, according to Ken Manuel, Duke’s reservoir aquatic plant manager.

“Early detection and rapid response is critical,” he said. “The plants grow so fast that you’re quickly past just a small infestation.

“Hydrilla grows faster than you think,” Manuel added. “It’s not just an inch a day. A plan can grow multiple feet per day from all of its growth tips.”

And too often, it’s spreading undetected. “Especially in the East, the states, which manage the fisheries and the water quality, rely on interested individuals to tell them about invasive plants,” the scientist said.

By contrast, Duke Energy’s mosquito control teams aren’t just controlling blood-sucking insects while they are on the water full-time for six months annually. “They are constantly looking for hydrilla and other invasive plants so that we can act quickly,” Manuel said.

Once hydrilla is confirmed, it is treated with herbicide. Sometimes, that is enough. More often it is not. That being the case, stocking of triploid grass carp follows, at a rate of 20 per acre of surface infestation.

The herbicide reduces the plant’s biomass, while carp graze on what sprouts from the surviving tubers. “If you have 1,000 acres of hydrilla, you have 1,000 acres until the tuber bank is exhausted,” said the scientist.

Additional “maintenance” stockings at a rate of 1 per 8 acres of the reservoir might follow for 8 to 10 years. 

(This article appeared orginally in B.A.S.S. Times.)