dragonfly – Potomac Environmental Research and Education Center

Written by: Chelsea Gray

How do you tell the health of a river? This is a question that scientist all over the world struggle to answer. A common method for determining stream health is the Stream Bioassessment.

Damselflies lay their eggs in the water. Damselfly nymphs live under the water and are an example of the type of benthic macro-invertebrate found in Virginia streams.

What is a “Stream Bioassment”?

Because you can’t ask a stream how it’s feeling, we use indirect measures of health for an ecosystem. One way we do this for a stream is by identifying what types of organisms live there. In particular, we look at benthic macro-invertebrates, or the bugs that live in the stream bed.

Damselfly Larvae captured from a NOVA stream

PEREC Faculty and George Mason Students spent a wonderful Saturday at the Occoquan River Fest. The festival was a great place for NOVA residents to learn about the history and environment of the Occoquan River.

PEREC’s booth at the Occoquan River Festival. Adults and children alike were interested in the crayfish!

PEREC’s booth was dedicated to the health and ecosystem of local Virginia streams. Students and Faculty provided some great hands on activities, by fishing out live organisms for visitors to see up close. Crayfish, amphipods, and cranefly larvae were caught from the river that day and temporarily held in a glass aquarium. Children were able to get up close and personal, using magnifying glasses to get a detailed look at the organisms from their backyard.

“It’s great seeing the excitement in young kids when they examine small critters like crayfish and cranefly larvae up close,” says Kim De Mutsert.

George Mason graduate and undergraduate students were able to practice their science communication skills, with children and adults alike. The students explained that the number and types of organisms found in a river help scientists determine how “healthy” (i.e. unpolluted) the waterway is.

But it wasn’t just GMU students doing to the teaching.

“It was so interesting to see how much the parents would learn from their kids,” Grad student, Jessica Melton says. “The kids would tell their parents that what we caught was only 100 meters away. They’d explain to them what a cranefly was (Parents often thought it was a nuisance or large mosquito) as it’s very common in the area. The parents realized that it’s actually a beneficial species to keep around.”

That kind of experience is what made the day a success.

An annual event, PEREC looks forward to next year’s Occcoquan River River Fest!