January-February 2010

Leaf Pack: Breaking New Ground by Studying Bugs

Onion bags filled with soggy leaves are bringing new life to the classroom—and new understanding of forest ecosystems.

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Photo: @iStockphoto.com/Antagain

By David C. Richardson

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Bob Connick regularly sends students from his chemistry class into the small stream that runs alongside Mahopac High School, in Mahopac, NY, to collect scientific data.

And Connick says they’re thrilled about it. “Especially the big guys. I had them out there after it snowed—they’re in their waders, cracking through the ice—and they come back, and it’s all laughing and talking: ‘This guy fell in, this one did that.’ After they get through all of that, I say, ‘But did you get the data I asked you to get?’ And they say, ‘Oh, yeah, yeah, we got it all—look!’”

For 20 years, Connick says, his pupils have been collecting all kinds of data on chemistry, temperature, and stream flow from this tiny creek in the woods of Putnam County, NY, 40 miles north of New York City. Over time, Connick says, he began to see changes in the creek, and not for the better.

A few years ago, he introduced to his classes a new way to evaluate the quality of the stream that he felt might shed more light on what was happening.

The program, called the Leaf Pack Network, focuses on the macroinvertebrates that colonize the leaf litter on the streambed. It was developed by educators at the Stroud Water Research Center in Pennsylvania and modeled after techniques used by professionals worldwide to evaluate the ecological condition of natural streambeds and their adjacent forests.

Liz Brooking, communications director for the Stroud Water Research Center, says the Leaf Pack kit is a simple tool, comprising mainly “inexpensive, readily accessible products.”

According to Brooking, educators at Stroud, in partnership with the LaMotte Company, which specializes in water quality testing equipment, conceived it as a simplified and inexpensive macroinvertebrate sampling kit that can be used by volunteers of all ages and all levels of scientific skill.

“The primary tool is an onion bag,” she says. Volunteers fill the onion bags with leaves gathered from the wooded areas near a stream. They then anchor the leaf packs to the streambed for several weeks to provide habitat for the tiny creatures that live in the waters.

Connick says it’s pretty simple to use. “We collect the leaves sometime in October and put them in. Then we take them out in December or January.”

Along with the onion bag, the kit provides aids to help identify the “bugs” that crawl into the leaf clumps. Brooking says the kit includes “little Petri dishes, and flash cards with photographs that illustrate the bugs that you’re supposed to be looking for—what are their shapes, what are they called, and whether they are pollution-sensitive or less so.”

“The only thing the volunteers have to supply are the leaves,” says Brooking.

When volunteers return to the stream to collect the bundles, they evaluate the mix of organisms they find in the soggy leaves as indicators of the stream’s health.

Connick encourages his students to devise their own unique experiments using the Leaf Pack kits. “I tell them how it works and let them decide what to do,” he says. “You could mix all different kinds of leaves; you could have a control pack; you could put all maple leaves in another pack; or you could do forested versus non-forested areas.”

A Bug’s-Eye View
Connick contrasts the Leaf Pack program with chemical testing, which he says “only gives you a snapshot of water quality for a day. There could be pollutants running through there at night, and the next morning we could go out with chemical tests and everything would look nice.

“But with Leaf Pack, these guys live there,” he continues, and studying them, he says, will provide clues to things that might “happen that we don’t know about.”

Connick says the packs his students collected from the creek were beginning to paint a picture of a stream in decline. “There were a lot of things like sow bugs, aquatic worms, and leeches, and that showed that there were a lot of organics involved,” he explains. Some of the effects, he thought, could be traced to grass clippings from the school’s lawn that sometimes ended up in the creek.

But he says there were other problems, too, which he confided to Putnam County’s Soil and Water Conservation manager, Laurie Taylor. According to Connick, a section of the creek where water once flowed freely had become clogged, and the bank had begun to spread out like a miniature “beach”—not an ideal environment for aquatic life.

Taylor agrees with Connick’s assessment. “Our big problem was the sand and the silt that was coming off the roads,” she says.

She explains, “With all of the old-fashioned catch basin drainage systems leading to this ponded area—basically a sediment basin—it was filling up. The ecosystem was changing, and he was actually starting to lose the area as a classroom.”

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The impact of these changes was not just academic. Mahopac High School had been designated as a municipal separate storm sewer system and charged with managing the quality of stormwater runoff entering the Lower Hudson River Drainage Basin from its grounds. And the creek, though small, flows into a prized trout stream. In addition, the watershed eventually feeds the Hudson River, which, Taylor notes, is where New York City gets its drinking water.

Connick and Taylor brainstormed over how to preserve the creek to reach both teaching and stormwater-quality goals. They decided to pursue a grant funded by the United States Fish and Wildlife Foundation. Next Page >

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