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Illinois tolls pitch in to save endangered dragonfly

State funds help support conservation efforts for the Hine's emerald dragonfly, many of which live along a highway.

September 01, 2009|Richard Wronski

LEMONT, ILL. — A motorist zipping along Veterans Memorial Tollway near Lemont, Ill., wouldn't think twice if a large green-eyed bug splattered on his windshield, but Dan Soluk would be heartbroken.

The demise of even one Hine's emerald dragonfly is of grave concern to Soluk, a biologist whose life's work is studying the endangered species.

Only a few thousand adult Hine's emerald dragonflies are believed to inhabit Illinois each summer, and many of them live near a 100-foot-high tollway bridge spanning the Des Plaines River Valley.

The tolls help support a wide-ranging scientific endeavor to catch, count and cultivate the 2 1/2 -inch Somatochlora hineana. That research pays the mortgage on what tollway officials jokingly refer to as "dragonfly condos," unique breeding areas designed to replicate the insect's habitat and propagate the species.

The Illinois State Toll Highway Authority has spent about $6 million on the dragonflies, including about $1.5 million to partner with the University of South Dakota and Soluk, a professor of aquatic ecology at the school and head of the Hine's project.

Officials are hopeful the conservation effort will boost the dragonflies' population, said Kristopher Lah, an endangered-species expert for the U.S. Fish and Wildlife Service.

The Interstate 355 bridge was built high to reduce car-dragonfly collisions, but Soluk has concluded that the insects are not flying beneath the road, perhaps because they don't like the wide shadow under the highway. As a result, they are not as likely to mate with dragonflies from the other side.

Experts say the dragonfly's survival is important to humans because it is an "indicator" species, a key barometer of the quality and quantity of groundwater.

"The same things that affect the Hine's are the same things that are going to affect humans, because we are also drawing down the groundwater, and we're not doing a lot to conserve it," Soluk said.

At least seven agencies, including forest preserve districts in three Illinois counties and the Army Corps of Engineers, have a stake in keeping the insect viable.

The Hine's was listed as endangered by the Fish and Wildlife Service in 1995, and its population now is officially labeled "stable or declining." The Illinois tollway authority adopted the research effort when it received federal permission to build the bridge, which spans two Hine's habitats: Will County's Keepataw Preserve and Black Partridge preserve in Cook County.

The two are among only 10 Hine's habitats in Illinois, totaling about 3,000 acres along the Des Plaines River Valley. The only other known breeding sites are in Door County, Wis.; Missouri; northern Michigan; and Canada.

The dragonfly lives only in wetlands covered with thin soil over dolomite bedrock and fed by calcareous, or "chalky," groundwater. Loss of this habitat to houses, agriculture and industry is the primary cause of the species' decline, experts say.

Soluk leads the team catching and tagging the elusive insects. One recent day, he and two graduate students, armed with long, gauzy nets, led a mad chase for specimens as the dragonflies darted and dipped among the tall grass and wild plants.

After capturing one, Soluk gingerly held the insect as an assistant affixed a minuscule identifying dot onto the dragonfly with a drop of epoxy.

Then a tiny piece was clipped from each wing. The fragments were bound for Soluk's colleague in South Dakota who is conducting genetic tests to determine the relationships between the specimens in each habitat.

The "dragonfly condos," in a former fish hatchery, are man-made ponds and rivulets that replicate -- or even improve -- the dragonflies' natural home.

"There's never been an attempt anywhere else to create a habitat that's manually manipulated," said Angela LaPorte, the tollway's environmental planner. "This is a unique project for this species."

Unlike a native habitat, conditions in the artificial ponds and rivulets, fed by an artesian well, can be adjusted to test the effects of change on the dragonflies. A turn of a crank can halt the flow of the iron-rich water to the habitat.

"We can make this a better habitat than the natural habitat," Soluk said. "We can produce higher numbers here, a bigger population density, than would normally be possible."

In an old building nearby, students monitored dragonfly larvae: dozens of hairy, cockroach-like critters kept in jars. Although the adult Hine's may live only a few weeks, larvae live for four to five years.

The bridge was built on 34 concrete piers, each of which consists of four massive columns. Its minimum height, 67 feet, was intended to let the insect fly beneath it. Instead, the bridge has become a barrier between the dragonfly populations on each side, Soluk has found.

Dragonflies are most active in sunlight, so it's possible the 30 to 40 yards of shade created by the bridge discourages them from passing underneath, Soluk suspects. The consequences of this are not clear, Lah said, but the species' genetic diversity could be affected.

Perhaps the most valuable lesson to be learned from the Hine's research isn't necessarily above ground, but below.

The Hine's has become so scarce not only because of the loss of habitat to development, but also because shallow aquifers have been tapped.

"People will have to ask themselves, 'How many persons can live in Lemont if Lemont has to draw its drinking water from the ground?' " Soluk said. "It's going to be one of those limiting issues."


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