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Virginia Brook Trout Streams Mostly Recovering From Acid Deposition

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"This is good news and real evidence for the value of our national investment in improving air quality," said Rick Webb, a U.Va. environmental scientist in the College of Arts & Sciences and coordinator of the Virginia Trout Stream Sensitivity Study. "At the same time, there is more to be done, and many Virginia brook trout streams may never fully recover."

U.Va., with the support of the conservation organization Trout Unlimited and several state and federal agencies, has been studying the health of Virginia's remote mountain streams since initiating a large-scale survey in 1987. Another such survey was conducted in 2000, and again in the spring of 2010. Quarterly sampling of stream water chemistry also is conducted in 66 streams and regularly in Shenandoah National Park.

The study demonstrates a clear improvement in water quality between the 2000 and 2010 surveys. Little improvement was noted between the 1987 and 2000 surveys. Webb attributes this to a delayed effect of streams' ability to purge acidification that has settled for years into surrounding soils and that continues to leach into streams.

Janet Miller, a graduate student in environmental sciences who analyzed survey data, found that 77 percent of the sampled streams in 2010 were suitable for brook trout reproduction. The 1987 and 2000 surveys showed that only 55 percent and 56 percent, respectively, were suitable for brook trout reproduction.

Webb attributes the improvement to the Clean Air Act Amendments of 1990 that imposed strict regulations on emissions from coal-fired power plants, as well as improvements to technologies that reduce emissions from power plants, automobiles and other machinery.

Between 1990 and 2009, sulfur dioxide emissions from coal-fired power plants declined by 64 percent. Dominion Virginia Power, as a notable example, removes 95 percent of the sulfur dioxide emissions from its largest coal-fired power plant, located at Mount Storm, W.Va., which is upwind of Virginia's mountains and Shenandoah National Park.

Organizers plan to continue long-term monitoring by conducting surveys every 10 years, and have launched a $500,000 fundraising campaign to support the ongoing studies. They emphasize the importance of maintaining such long-term research on trout streams in Virginia – not only for monitoring their recovery from acid rain, but also for understanding the potential effects climate change and other man-made disturbances.

The Virginia Trout Stream Sensitivity Study is one of the nation's largest and most comprehensive long-term stream chemistry surveys. It is designed to track the effects of acidic deposition (often called acid rain) and other factors affecting water quality and related ecological conditions in Virginia's native trout streams.

The brook trout is the only native trout in Virginia and the eastern United States. The fish require clean water to propagate and are highly susceptible to acidity deposited to the water from pollution in the air. Brook trout, and the generally pristine and remote streams they inhabit, are considered indicators of the overall health of the environment.

In the study, water samples are analyzed for sulfate levels and a stream's natural ability to neutralize acidity. The researchers are finding that sulfate levels are dropping in most streams, indicating that air pollution reductions are having a positive effect on the environment. Due to prevailing winds that carry pollution from coal-burning power plants – primarily sulfur dioxide and nitrogen oxides – many mountain streams and forests in Virginia and throughout the Southeast have suffered long-term damage.

A given stream's level of susceptibility to acidification is affected by its bedrock composition and the chemistry of nearby soils. Streams with sandstone or quartzite bedrock – about one-third to one-half of the native trout watersheds in Virginia – are most vulnerable to acid deposition because they do not neutralize acid even years after pollution has been reduced.

During the 2010 survey, 165 volunteers, mostly from Trout Unlimited and some government agencies, sampled 384 streams, which, together with the program's 66 routinely sampled streams, represent about 80 percent of the forested mountain headwater streams in the state that contain reproducing brook trout.

"Through the years this has continued to be a team effort between U.Va. scientists, Trout Unlimited and the U.S. Park and Forest services, the EPA and the Virginia Department of Game and Inland Fisheries," said Jack Cosby, an environmental scientist who co-directs the stream study effort. "We've even received a lab equipment grant from the Dominion Foundation. The cooperation between entities that might sometimes seem to be at odds has been inspiring."

Data from the survey helps scientists determine the health of headwater streams throughout western Virginia. The U.S. Environmental Protection Agency and other federal and state agencies use such data to inform resource management and to develop, evaluate and recommend national air pollution control policies.

"It's a cause for hope that so many people share a determination to protect and preserve out brook trout streams and the natural world they represent," Webb noted. "The remarkable volunteer contribution to the trout stream surveys over more than two decades is a real testament to this determination."

Fariss Samarrai | Quelle: Newswise Science News
Weitere Informationen: www.virginia.edu

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