A motorist zipping along Veterans Memorial Tollway near Lemont might not think twice if a certain large bug with enormous green eyes gets 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 about 100 feet below the deck of the tollway bridge spanning the Des Plaines River Valley.
Tollway users may care to know that every time they drive through a tollbooth they are helping 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 dragonfly protection effort. That includes about $1.5 million partnering with the University of South Dakota and Soluk, a professor of aquatic ecology at the school and head of the Hine’s project.
It’s too early to tell yet but officials are hopeful the conservation effort will eventually boost the dragonflies’ population, said Kristopher Lah, an endangered-species expert for the U.S. Fish and Wildlife Service.
The Interstate Highway 355 bridge was built higher to reduce car-dragonfly collisions, but Soluk has concluded the insects are not flying beneath the road, either, perhaps because they do not 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 the species serves as a key barometer of the quality and quantity of groundwater. The Hine’s is an “indicator” species, like the proverbial canary in the coal mine.
“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, from Forest Preserve Districts in DuPage, Cook and Will Counties to the Army Corps of Engineers, have a stake in keeping the insect from becoming roadkill.
The Hine’s was listed as endangered by the U.S. Fish and Wildlife Service in 1995, and its population now is officially labeled “stable or declining.”
The Illinois State Toll Highway Authority adopted the research effort when it received federal permission to build the bridge, part of the $730 million extension of I-355, linking Interstate Highway 55 in Bolingbrook with Interstate Highway 80 near New Lenox, completed in 2007. The bridge spans two Hine’s habitats: Will County’s Keepataw Preserve and Black Partridge Woods in Cook County.
The two are among only 10 Illinois Hine’s habitats, 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.
One reason the Hine’s is so scarce is that its habitat is geologically rare. 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 on a tract that was once a fish hatchery adjacent to DuPage County’s Waterfall Glen Forest Preserve.
On one recent day, Soluk 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 in his hand 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. The goal is to determine the relationships between the specimens found in each habitat.
The fish farm is the site of the “dragonfly condos.” These man-made ponds and rivulets comprise an artificial habitat that replicates — and even improves — 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 brownish, 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.”
Loss of suitable groundwater is one of the biggest threats to the dragonfly. Because the fish farm is in Waterfall Glen, that aquifer is protected. Not so the other sites, Soluk said.
In an old building nearby, students monitored dragonfly larvae: dozens of hairy, cockroach-like critters kept in jars.
While the adult Hine’s may live only a few weeks, larvae live for two to four years in crawfish burrows among the kind of natural rivulets found about a mile west of the fish farm, under the six-lane I-355 bridge.
The bridge was built on 34 concrete piers, each of which consists of four massive columns. It was built with a minimum height of 67 feet to enable the dragonfly to fly below and not become road kill. It has had the unintended consequence of becoming a barrier between Keepataw and Black Partridge, 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 yet clear, but there could be a limiting effect on the species’ genetic diversity, Lah said.
Perhaps the most valuable lesson to be learned from the Hine’s research isn’t necessarily above ground, but below. One reason the Hine’s has become so scarce is not only the loss of habitat to development but also the tapping of shallow aquifers.
“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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rwronski@tribune.com
Preservation concentration
See the Hine’s emerald dragonfly in its habitat at chi cagotribune.com/dragonfly
