By DAVID GREEN
There are hundreds of different midges in the world. There are so many kinds of the little fly, says Jeff Cooper, that scientists have divided them into tribes.
One variety of midge emerges from a larva known as a bloodworm. The small, red worm-like creature is common in streams throughout Michigan, said Cooper, a researcher with the Michigan DEQ’s Surface Water Quality Assessment Section.
They thrive in cold trout streams as well as in warmer, slower moving rivers such as Bean Creek. They’re also common in oxygen-deprived contaminated water.
When Cooper sees bloodworms and nothing but bloodworms, he starts to worry. That was the situation when he walked up Medina Drain from the Bean last month.
Medina Drain originates near Dillon Highway, meanders east under Ingall Highway and finally joins the Bean about half a mile west of the village of Medina.
“There’s gravel and cobble,” Cooper said, “but there’s almost nothing living on it.”
His partners from the DEQ’s rapid bio-assessment team—Kevin Goodwin and Tamara Lipsey—are finding just the opposite in Bean Creek. They’re collecting samples from the bottom of the Bean, and they’re finding dozens of specimens.
Cooper speculates that Medina Drain is too oxygen-deprived for most insects other than bloodworms to exist.
“If you can’t live on the surface or store oxygen, you don’t live there,” he said.
Bloodworms can handle the lack of oxygen. They’re red because, like humans, they carry hemoglobin inside of them. This enables them to store their own supply of oxygen and rely less on the dissolved oxygen present in water.
Cooper was finding a hundred bloodworms in a handful of silt from the drain, much more than from a handful of Bean mud.
Bloodworms can offer one indication of stream health, Cooper said, due to their tolerance of poor water conditions. As a stream becomes more impaired, bloodworms still thrive where other insects can’t.
Cooper’s team is involved in a special project to study the possible impact on aquatic life from two large dairies in the area.
The dairies were fined by the DEQ for discharging nutrients into area streams. Cooper’s job is to collect data to help the agency’s enforcement section make good decisions.
They’ve collected and catalogued macroinvertebrates and fish from several tributaries in Hillsdale and Lenawee counties and today they are taking a look at the Bean itself.
Silt is one of the biggest causes of impaired water quality in streams and rivers. Most insects and fish need a stable environment to survive, Cooper explains, and silt moves easily with even slight changes in water flow.
Excessive silt is often linked to the loss of vegetation along river banks, from row crop agriculture and from heavy stormwater flow—when silt-laden water flows into a stream rather than infiltrating into the soil.
Cooper heads up the drain. Goodwin and Lipsey begin collecting specimens near the outflow of the drain.
Goodwin explains they will sample a variety of habitats since there are subtle differences in each location. Soft silt. Gravel. Woody debris. Leaf packs. Under banks.
Lipsey walks toward the far bank while Goodwin samples closer to shore near the mouth of the drain.
“The slower areas are a refuge for minnows,” he says.
Minnows aren’t large enough to handle the main current, and besides, they would likely end up in the stomach of something larger.
He peers into his net at the silver flashes of minnows jumping in the sunlight. One is larger than the others and he identifies it as a silverjaw. That’s a fish he had never seen before visiting the Bean. The northern range of the silverjaw doesn’t extend too far into Michigan.
Goodwin digs some gravel from the stream bed, empties it into a pan and begins watching for movement.
“We spend a lot of time staring into a pan.”
He’s finding wigglers that will turn into midges, dragonflies and damselflies. There are water mites and caddisflies and tiny crayfish. Most everything in the pan will eventually leave the water and grow into an airborne insect.
From three feet away, just about everything he lifts from the pan looks alike—it’s less than half an inch long and it wiggles.
“Just watching them move is half the trick to identifying them,” Goodwin says.
Up close, there’s a whole new world of life unfolding. Dragonfly larvae have clubbed antennae. The dixid midge has a little black square head. What will later emerge as a no-see-um now looks like a tiny cigar—pointy head and pointy tail.
Goodwin points out a flat-head mayfly that has three tails, each as long as the body. A little black ball moving across the pan is identified as a water mite.
“For as small as they are, it’s fun to look at them under a scope,” he says, “because they have some pretty brilliant colors.”
He finds a small burrowing mayfly, but Lipsey soon brings in a much larger specimen.
“That’s the granddaddy of them,” Goodwin says. “That’s a huge one. It’s good to find them.”
Burrowing mayflies are typically found in more stable systems. If the sand and silt covering are frequently washed away, the insect is more likely to be devoured by something higher up on the food chain.
“If the mayflies are happy, we’re happy,” Cooper says later.
It’s an interesting organism to watch lying in his hand, but the real show begins once it’s placed back in water. That’s when a pair a feathery gills begins to waver like something from a fantasy film.
Cooper soon returns from his trek up the drain and delivers his bleak report. He fills out some paperwork while Goodwin looks over a piece of tree bark that was submerged in the river.
Tabanid (deerfly). Athericid (watersnipe fly). Leptocerid (long-horned caddisfly). He quickly names off half a dozen small creatures that Cooper notes on his clipboard.
The trio soon packs its gear and heads back upstream to the pickup truck parked at Medina Road.
Cooper will compile lists of what was found—and what was missing—at the various locations visited and make sense of the data collected.
That’s when he’ll know more about Bean Creek’s current state of health.
- Aug. 13, 2003