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Media Contact:
Dave Penrose, 919/515-8244
Tracey Peake, News Services, 919/515-3470

July 25, 2005

Some Aquatic Insects “Bugged” by Pollution, Researchers Say


Stoneflies are the aquatic insects most sensitive to water pollution.
Stoneflies are the aquatic insects most sensitive to water pollution.

Have you seen a stonefly or mayfly lately? If you have, then chances are the water you found it in is relatively clean. Scientists at North Carolina State University are using the smallest residents of our rivers and streams to help assess a big concern – aquatic pollution levels.

Aquatic insects such as mayflies, caddis flies and stoneflies are not only popular with the fly fishermen who prefer them as bait, they’re also popular with environmental scientists. Since these insects spend their entire lives underwater, they are an excellent source of information on what types of pollutants are present in rivers and streams.

Dave Penrose, a research associate in NC State’s Department of Biological and Agricultural Engineering, says that scientists have been studying aquatic insects for the better part of a century, but it wasn’t until the advent of the Clean Water Act in 1972 that states began hiring biologists to come up with classification criteria for pollution, criteria that also included information on the presence or absence of certain insects.

Aquatic insects are a much more reliable indicator of pollution than fish, due to the greater variety of insect species. There are more than 350 species of mayfly in North Carolina, for example, representing an entire range of water quality tolerances, which enables researchers to be more specific about the type of pollutants found in particular waterways.

The aquatic insect most sensitive to water pollution is the stonefly, while certain species of caddis fly thrive in streams compromised by agricultural or even sewage treatment runoff. By capturing and cataloging the numbers and species present in a given body of water, scientists are able to determine what types of pollutants may be present as well as the pollution levels.
Professionals and laypeople can do informal water quality surveys if they know what to look for, Penrose says. Penrose and his colleagues offer taxonomy workshops for environmental agents and volunteers alike, teaching them how to properly “read” their insect findings. For more information on these workshops, check the Web.

“These insects are like the canaries in the coal mine for water quality,” Penrose says, “and the beauty of it is that anyone can gather this data if they know what to look for.”

- peake -


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