Trout Stream Sensitivity Study 2000
Virginia Trout Streams Continues,
23, 2000 -- Preliminary
findings from a survey conducted in April 2000 of 452 Virginia brook
trout streams indicate some recovery from the acidification levels
found in a 1987 baseline survey. The results, however, will require
further analysis because they may be strongly influenced by differences
in stream flow levels at the two separate points in time -- sampling
in April 1987 took place under much wetter conditions than sampling
in April 2000.
More importantly, long-term monitoring
during the 12-year period -- using quarterly sampling of many of
the same streams -- indicates acidification is continuing, and generally
worsening, for most Virginia brook trout streams. Results of the
quarterly monitoring also indicate that acidification may have caused
biological harm to native brook trout.
"We have found that brook trout
streams in Virginia are continuing to degrade," says Rick Webb,
coordinator of the study and a research scientist in the Department
of Environmental Sciences at the University of Virginia. "Our long-term
monitoring provides little evidence of recovery."
The quarterly monitoring of trout
streams -- and the larger 1987 baseline and 2000 followup surveys
-- are part of the Virginia Trout Stream Sensitivity Study (VTSSS),
a joint effort by several agencies and organizations to monitor
chemical change, as a result of "acid rain," in acid-sensitive watersheds
following enactment of the Clean Air Act Amendments of 1990. The
amendments called for an approximately 40 percent reduction of sulfur
dioxide emissions from coal-fired power plants by this year.
The VTSSS 1987 survey provided baseline
data of stream conditions before enactment of the amendments. Followup
surveys are used for comparison, to determine what changes have
occurred. Quarterly monitoring -- which so far has covered 48 points
in time -- provides the most reliable measure of change because
it factors in numerous stream flow fluctuations. Stream flow levels
can strongly influence water chemistry samples.
VTSSS was designed by environmental
scientists at the University of Virginia and the ongoing analysis
of data is conducted by those scientists. All of the streams surveyed
are considered to be biologically and geologically representative
of trout streams throughout the Virginia Appalachians.
Trout Unlimited, a national cold
water fisheries conservation organization, provides partial funding
for the project as well as numerous volunteers who help collect
Acid deposition, which is often
called "acid rain," is the deposit of airborne acidic material from
sources such as coal-burning power plants into streams, rivers and
lakes as wet precipitation (rain, snow, fog, cloud) and dry precipitation
(dust and gases). Acid deposition is responsible for the documented
loss of hundreds of fish populations in Europe and North America.
The burning of fossil fuels release
into the atmosphere sulfur and nitrogen oxides, which are converted
to sulfuric and nitric acids. Coal-burning power plants in the Ohio
River Valley are a major source of this pollution, which is carried
east on prevailing winds.
Depending on the bedrock geology
of a particular stream, these acids can create a situation that
is deadly to fish. Acids release aluminum from the soil, resulting
in an environment that is toxic to fish and aquatic insects. In
surface waters at lower elevations, acids are usually neutralized
because weathered bedrock has a buffering effect on acids that have
entered streams and lakes. But at the higher elevations where brook
trout live, the hard unweathered bedrock of headwaters has little
buffering effect, allowing excessively high acidic conditions to
develop. These acids accumulate over time, and even when the source
of the pollution has been reduced, it may take years for the stream
chemistry to respond. During that time the entire population of
fish in a stream may become extinct.
"There is an apparent lag time
in stream recovery," Webb says. "Our data show that stream quality
is declining even as air quality has improved. Among 58 of the long-term
monitoring streams for which 12 years of quarterly sampling data
is available, acidity levels have decreased in only 15 streams.
Acidity levels have increased in the rest."
According to Art Bulger, a U.Va.
research scientist and one of the study authors, the hydrogen ion
that is derived from sulfuric and nitric acids and the soluble aluminum
create a poisonous combination for the fish. "The toxic action occurs
at the gill, resulting in blood and body fluid disturbances leading
to circulatory collapse. The fish basically has a heart attack,"
Of the three species of trout
in the eastern U.S., the brook trout is the only native to the region,
and is the most acid tolerant, Bulger says. Non-native rainbow trout
and brown trout are more sensitive to acidification, and may experience
greater declines due to this process.
VTSSS has received financial
and other support from the U.S. Environmental Protection Agency,
the National Park Service, the U.S.D.A. Forest Service, the Virginia
Department of Game and Inland Fisheries, the Izaak Walton League
of America, the Federation of Fly Fishers, as well as Trout Unlimited.
The study authors include U.Va. scientists Rick Webb, Frank Deviney,
Jack Cosby, Art Bulger and Jim Galloway.
Contact: Fariss Samarrai, (804) 924-3778