Science Wednesday: Bringing the Outdoors In

Each week we write about the science behind environmental protection. Previous Science Wednesdays.

By Cathryn Courtin

Thinking about stream research evokes images of scientists wading into streams hunched over, collecting samples and taking measurements. At EPA’s Experimental Stream Facility (ESF), however, small stream research takes on a new form.

The facility houses eight indoor small streams called “mesocosms.”

The technological features of the ESF enable scientists to conduct experiments that mimic natural settings while precisely controlling and studying certain variables.

I recently talked with one of the lead scientists, systems ecologist Christopher Nietch, Ph.D., and learned all about this high-tech facility and its significance. One thing he stressed is that the team works hard to ensure that real field data is studied carefully and used inside the facility.

“We have spent a great deal of time characterizing operational conditions that help define realism and applicability, and we try to provide information about conditions that are found in reality and how ours compare,” said Nietch.

Problems that might arise when experiments are conducted in the field can be overcome using the specialized tools in the facility. Nietch explained, for example, that it can be difficult to determine which chemicals and pesticides are responsible for which changes in the ecosystem and which chemicals are most harmful when conducting studies in the natural environment.

In the facility, doses of contaminants can be adjusted to relevant quantities and studied individually or in specific mixtures while controlling other variables. It then becomes possible to determine what effect each contaminant has, how its impacts change when mixed with other contaminants, and which contaminants are most threatening.

Other factors that researchers have control over that they wouldn’t in nature are the light levels, water source, flow rate, length of the stream, and streambed composition.

It was eye-opening to hear Dr. Nietch say that “small stream ecosystems represent about 90% of the linear drainage footage in any watershed… but rarely do those [watershed] models consider what changes might be taking place within the small scale ecosystems.”

Given the vast percentage of the watershed that these streams make up, they must play a role in watershed health, but this role is not yet well understood. To better this understanding, scientists at the ESF are breaking through the boundaries of traditional methods and using this unique facility to widen research possibilities.

About the Author: Cathryn Courtin is a student at Georgetown University in the Science, Technology, and International Affairs program. She is spending her summer working as a student contractor at EPA’s Office of Research and Development.

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