Somewhere in the vast Oak Openings region of western Lucas County, sixteen volunteers armed with buckets, microscopes and small nets on poles are on an expedition. But what are they looking for?

The intriguing part of vernal pool monitoring is that you never know for sure.

“There’s always something new,” said Eileen Sawyer, a volunteer who started the Metroparks Vernal Pool Survey, where participants are still making discoveries seven years later.

Vernal pools are very shallow, temporary stands of water with no outlet, usually in woodlands. They can be the size of a swamp or as small as a puddle, stay wet for days or years, but what they all have in common is that at some point they dry up.

Another critically important trait is what they do not have: fish.

The absence of fish make vernal pools “biological hotspots,” said Sawyer. Every venal pool has wood frogs, salamanders, fairy shrimp, fingernail clams and other species that need these tiny wetlands to bear their young, which would be eaten by fish in regular ponds.

Volunteer monitors use fine nets to collect samples from pools in various Metroparks then examine the contents of their buckets under microscopes, recording what they see. They take stock of plants, algae, aquatic insects, dragonfly larvae, frogs, turtles, snails, phantom midges, snakes and more.

The data are kept and compared from year to year, looking for trends that may be clues to the health of the ecosystem. The information is also shared with the Ohio Environmental Council and a national program called Frog Watch USA.

“I tell new volunteers that after one day of participating in the survey, I don’t think anybody ever looks at a puddle of water the same way again because now they know what’s in it,” Sawyer said.

The volunteer monitors have worked at Oak Openings Preserve, Swan Creek Preserve and Secor Metroparks. They look not only at the pools, but what’s around them that may affect the ecosystem as a whole. Over seven years, they have monitored nine pools and found each one to be very different from the next.

For example, at Secor, they found an abundance of aquatic worms in the water, while at Oak Openings they find very few. The difference is suspected to be the type of trees nearby: maple and tulip trees dominate at Secor, while tannin-filled oak trees are most common at Oak Openings. Even within the same park, such as Oak Openings, pools just a half-mile apart can be “completely different,” Sawyer said.

Timing can be important, too. One weekend, volunteers counted 805 water fleas; two weeks later in the same pool, they found 6,550.

“A bucket of water from a vernal pool is a window into an aquatic world that I didn’t know existed before I started this,” Sawyer said. “Each bucket’s a story of the vernal pool you’re at.”

Sawyer became interested in vernal pools in 2001 when she went back to school to complete a degree in environmental science at Bowling Green State University. There she met instructor and Metroparks naturalist Kim High, who suggested the project. By the end of semester, she had a program “on paper.” Denise Gehring, then director of environmental programs at Metroparks, encouraged Sawyer to bring her plan to life.

“Starting in the 1980s, our monitoring efforts had been more traditional--species and land-based, with an emphasis on rare species,” said Gehring, who is now retired. “Plant, insect, mammal, amphibian and bird research were led by staff with the assistance of volunteers. My concern, too, was that we were missing a whole portion of the ecosystem by not assessing the quality of the wetlands.”

The Vernal Pool Monitoring project looked at the habitat as a whole, Gehring said. The bonus was that Sawyer’s project would be accomplished entirely with volunteers.

In Sawyer, Metroparks found “A volunteer in a million,” said High.

To date, 280 volunteers have devoted more than 1,600 hours to the project. They include college students and faculty, park staff, Zoo Teens, naturalist volunteers, out of town guests, grandkids, neighbors and spouses.

“They all seem to be just fascinated with what’s in the water,” Sawyer said.

This summer, Sawyer is taking a break from the volunteer project after joining the Metroparks staff as a forest monitor assistant, working with park district and U.S. Forest Service staff. But her vernal pool program lives on under the direction of other volunteers, most of whom she trained.