Insects as Indicators

By Marguerite Huber

Twelve spotted skimmer dragonfly perched on a reed.

Twelve-spotted skimmer. Image courtesy of the U.S. Fish & Wildlife Service.

Scientists have developed ways to use certain species as kinds of “living barometers” for monitoring the quality of the environment. By studying the abundance, presence, and overall health of such indicator species, they gain insight into the general condition of the environment. Now, EPA researchers are developing ways to use insects in this way to explore the effects of environmental contamination and how it might spread across a watershed.

The Superfund program, established by the Comprehensive Environmental Response, Compensation and Liability Act, identifies sites that contain hazardous substances, such as pollutants and contaminants, that may pose a threat to human health or the environment.

Superfund sites include former landfills, industrial and military complexes, and abandoned mines.

In their study, EPA researchers sought to determine if insect communities could be used to measure the benefits of Superfund site clean-up and to monitor the effectiveness of site remediation and restoration. To be accurate, they also had to account for the differences between impacts from Superfund contaminants, and those related to urbanization.

The researchers compared a number of indicators related to urbanization, such as land development, housing unit density, and road density.

In the end, the researchers found that once they had accounted for the effects of urban development, they were able to use insects as indicators for detecting the effects of Superfund sites in the watershed. Using what they learned from that work, they also developed models that can discriminate the effects of Superfund activities from those of development upstream, and help identify those streams where impacts exceed what would be expected based solely on the amount of development across a watershed. Researchers and others can also use the models to assess the effectiveness of remediation efforts at contaminated sites.

Overall, developing methods to tap insects as indicators is helping EPA researchers understand how Superfund sites affect entire watersheds. It’s a big step toward cleaning them up and helping EPA fulfill its mission of protecting human health and the environment.

About the Author: Marguerite Huber is a Student Contractor with EPA’s Science Communications Team.