Sightline, Summer 2001, Great Smoky Mountains Aquatic Insects, Water Quality, University of Tennessee

SIGHTLINE

SUMMER 2001
Vol. 2 No. 1

AIR
The Acid Test

HUMAN INTERACTION
Back to the Future

WILDLIFE
Deviant Behavior

WATER
Aquatic Insects on the Frontline

INVASIONS
Big Hogs, Big Problems

VEGETATION
Managing the Land

SIGHTLINE
is published on behalf of
Great Smoky Mountains National Park
by the
Energy, Environment and Resources Center (EERC)
at the
University of Tennessee.

EERC conducts research designed to promote real-world solutions to problems in the fields of energy, environment, technology, and economic development.

SIGHTLINE is sponsored by:

Friends of Great Smoky Mountains National Park

and

Great Smoky Mountains Natural History Association

Photos courtesy of National Park Service

SIGHTLINE

SUMMER 2001
Vol. 2 No. 1

AIR
The Acid Test

HUMAN INTERACTION
Back to the Future

WILDLIFE
Deviant Behavior

WATER
Aquatic Insects on the Frontline

INVASIONS
Big Hogs, Big Problems

VEGETATION
Managing the Land

Aquatic Bugs on the Frontline

The National Park Service looks to aquatic insects to provide early warning of declining water quality

BY KRIS CHRISTEN

Some 2,000 miles of streams flowing in Great Smoky Mountains National Park, and high amounts of annual rainfall, support a highly diverse aquatic insect population-more than 500 species and counting-which makes these creatures excellent indicators for assessing water quality.

"These critters are there all the time, and they have to either survive or not survive the environmental conditions they're faced with," says Chuck Parker, a research aquatic biologist for the U.S. Geological Survey stationed in the Park. "The idea is that the organisms respond to what's there, and if they're healthy, we can assume that the river's healthy and not being strongly stressed."

So far, the news is good. "At this point, we don't have any strong evidence that there are serious problems with aquatic insect populations in general," Parker says.

Much of the stream monitoring began back in the late 1970s with the push to study the effects of acid deposition. These ongoing observations have helped National Park Service (NPS) researchers identify and chart trends in the Park's aquatic insect populations that might be related to environmental factors.

"What we're looking for are any signs of change in the Park's ecosystems, especially changes in the negative sense," Parker says. In addition to aquatic macroinvertebrates, the monitoring program also looks at forest communities, plants, wildlife, and fisheries.

The water-quality part of the program involves the collection of samples every summer from a series of sites representative of various areas in the Park-such as different forest types and elevations. "We take a look at the abundance and diversity of what we collect from year to year and see how that changes," says Becky Nichols, an NPS entomologist. And while the number of insects may not decline with decreasing water quality, the types of insects found will change.

Because researchers are looking for community-wide indications of health, the species they encounter have to be evaluated in terms of responsiveness to different types of stress. "Some species are very sensitive to certain types of pollution, whereas others are extremely tolerant, whether it's chemical pollution, siltation, or other disturbance," Parker says.

Of particular interest are the three primary aquatic orders-namely Ephemeroptera, Plecoptera, and Trichoptera, better known as mayflies, stoneflies, and caddis flies, respectively. These include some of the most intolerant bug groups. In addition, there are the aquatic midges, or flies, belonging to the Chironomidae family, which also includes many different species that as a whole exhibit a range of responses to virtually any type of pollutant.

Counting Game
Because responses are species specific, researchers calculate a so-called biotic index based on the species' tolerance value, which in effect gives each species a score from zero to 10-zero meaning that everything affects them; 10 meaning that nothing affects them. Then, "by combining the relative abundance of species with their tolerance to different types of pollutants, we come up with a community-wide estimate of water quality," Parker says.

Of course, all this information has to be calibrated, depending on the ecoregion, says Dave Lenat, a biologist with North Carolina's Department of Environment and Natural Resources, which has been the real leader with this approach.

"We might make adjustments if the stream is very small [and has] fewer species, or if we sampled outside the summer time period," he says. Likewise, years of high rainfall amounts or, conversely, drought years can affect bug populations and have to be considered as well.

"If you end up with a stream that's only populated with very tolerant species, your biotic index will go down, and you know something's up," Nichols says.

High Water Marks
Numbers crunched for streams in the Smokies typically fall into the good to excellent range, meaning that the streams are relatively pristine. Some areas do raise cause for concern, however, particularly those endowed with Anakeesta rock formations, which leach sulphuric acid and heavy metals when exposed to weathering. This pyritic rock occurs throughout the Park, the most dramatic example being Anakeesta Ridge located between Newfound Gap and Mount LeConte, where numerous landslide scars can be seen.

"Streams directly affected by Anakeesta runoff tend to be virtually devoid of all life," Parker says. Most of the affected areas in the Park are caused by natural events, but past roadbuilding activities and improperly disposed fill from debris slides contribute to the problem, he adds. Likewise, unwise logging activities in the Park at the turn of the century, followed by fires that eliminated all of the vegetative cover, could still be affecting stream life.

"It takes many decades for exposed Anakeesta to eventually reach the point where it's no longer contributing to downstream problems," Parker says.

Other concerns involve headwater streams at higher elevations, which are known to have pH problems from nitrate and sulphate deposition, in part from air pollution. But how that affects the insects is not yet known.

"We're currently reviewing our plan to perhaps focus more effort on higher elevation streams," Nichols says.

Changes in the forest as a result of the balsam wooly adelgids killing fir trees, particularly at higher elevations, also can affect aquatic bug populations. "This opens up the canopy, and we get a distinct change in the amount of sunlight that reaches the stream and the nature of vegetation that grows in the area of streams," Parker says.

Park researchers are keeping an eye on other pests approaching the Park's boundaries, including the hemlock wooly adelgid and gypsy moth, both of which could have devastating effects on the forests and streams, Parker says.

Data gleaned from water-quality monitoring plays a major role in decisions relating to Park construction projects, according to Bob Miller, Park spokesperson. For example, the existing 15-mile stretch of the Foothills Parkway was built by the Tennessee Department of Transportation (TDOT) by making big cuts and fills into slope sides. The process involved a lot of earth moving, exposed a lot of pyritic rock, and resulted in significant siltation and acids released to the point where some streams suffered major damage, according to Miller.

TDOT's contract was suspended as a result, and the Federal Highway Administration will build the last 1.5 mile segment using a series of 10 bridges that avoid cutting into the hillside and filling up banks below the roadbed.

"The whole idea behind it [the new project] is minimizing impact on the ground and the amount of disturbance, which produces siltation and impacts streamsheds," Miller says. "The downside is that it'll cost $60 million to $70 million to finish the project using our method, whereas the traditional cut-and-fill method would be tens of millions of dollars cheaper."

Similar considerations are influencing a project to reline and enlarge two tunnels along Newfound Gap road. Here, the Park is choosing to conduct all the expansion by lowering the existing roadway. As different rock strata are uncovered, those containing acid-bearing rock will be trucked up to a disposal site further up the mountain where they'll be graded out, neutralized with lime, and covered over. In this way, "water seepage will be minimized, and what seepage does occur will be neutralized," Miller says.

Water-quality monitoring is also playing directly into the All Taxa Biodiversity Inventory (ATBI) being conducted in the Smokies. The ATBI seeks to inventory all life forms in the Park. At least three new aquatic insect species have been found recently (see related article on page 13), and the species list keeps growing, according to Nichols.

She and Parker will soon be evaluating insect data collected over eight years, which they hope will identify any disturbing trends. "When we collect and analyze a water sample, we only get a snapshot of conditions; looking at the overall health of aquatic bugs may just give us the overarching view we really need," Parker says.

For more information, contact Becky Nichols or Chuck Parker, Great Smoky Mountains National Park, 1314 Cherokee Orchard Road, Gatlinburg, TN 37738, or call 865-436-1702.