Life in a Pond: water quality studies 2009.09.16
By DAVID GREEN
Pick up a rock from a river or pond, turn it over and stare at it for a while. It’s going to take a few moments, but you’ll soon see it come to life.
Under a tent near the road, guests were learning how to tag monarch butterflies from Pat Hayes of Kelley’s Island. But back in a field another tent was erected near a pond and that’s where Anne and her husband, Steve, were talking about aquatic life.
“Do you see anything alive on this rock?” she asked some children. “There’s a planaria, an aquatic worm. Over here is a beetle larva.”
There were also some caddisfly larvae and more.
“There are probably 15 different things that make their home here—and try not to be fish food,” Anne said.
Anne is coordinator of the Northwest Ohio Stream Quality Monitoring Program for Ohio Scenic Rivers—a branch of the Department of Natural Resources. She said she felt a little out of her element standing next to a pond. She’s accustomed to the running water of a river, but she’s impressed with what she’s seeing in this wetland.
“In a wetland you can find many of the same things as in a river, but different species,” she said.
She doesn’t know everything she’s seeing in this pond, but she and Steve brought along some specimens from a stream near their home in Putnam County, just in case they didn’t find what they were after here.
Dragonflies and damselflies were buzzing around the pond. Meadowhawks and eastern pondhawks and more.
“There goes a widow skimmer,” Steve said. “They eat mosquitoes like crazy.”
The dragonflies are fun to watch, but it’s the larvae that interest Anne. What lives in the water indicates the quality of the water, and when something is missing, there’s a problem.
“You can gauge the health of a water source by what’s missing from the food chain,” she said. “If certain things aren’t there, the whole food chain falls apart.”
Water quality could be tested on a chemical basis, Anne said, but biological monitoring is cheaper and a lot more fun. She lets Steve take over for the entertaining portion of the show.
He starts off by showing a dragonfly nymph in a small plastic case with a magnifying glass built in. As it’s passed around the audience, Steve notes that dragonflies spend as much as five years underwater before emerging as adults.
He likens its mouth to a beast from a horror movie. It’s almost like a mouth within a mouth. The lower jaw unhinges, folds out and surrounds the prey.
Next he shows the smaller damselfly nymph and then the water scorpion.
“Even though their name sounds horrible, they’re pretty harmless,” he said as a water scorpion crawled around his hand.
It resembles a walking stick and it’s in the same family as the praying mantis. It’s actually a bug.
“All bugs are insects,” Steve says, “but not all insects are bugs.”
A typical insect uses its jaws to tear up the food it eats, but not the bug. It injects an enzyme into its prey, then sips out the resulting liquid meal.
“Even though the water scorpions spend 99 percent of their lives in the water, they’re actually terrestrial animals,” Steve said. “They’re pretty ungainly fliers, but they can fly.”
They’re usually in the water hunting, their tail sticking up through the water to breathe through like a snorkel.
He passed around a crayfish, noting that it looked like a small lobster. Anne confirmed that the taste is similar, too.
Crayfish generally move backwards in the water. They have gills for breathing in their life under water, but they also possess lungs for time spent on the land.
Anne asked audience members to guess the number one factor leading to water quality problems. The responses danced around the correct answer, but didn’t hit it right until someone suggested soil-laden runoff.
“The biggest impact is the amount of dirt aquatic animals have to filter out,” Anne said. “It’s like breathing smoke 24 hours a day.”
Satellite photos show the plume of brown water leaving the Maumee River and entering Lake Erie.
She demonstrated how a turbidity stick is used to gauge water clarity. The 36-inch clear tube is filled with water and the user looks down into the tube from the top. Water is poured out a little at a time until a dark spot at the bottom becomes visible.
The pond water looked clear in the tube, but algae breakdown prevented seeing the bottom until the depth was down to about 25 inches. At the Maumee, Anne said, seven to nine inches is generally the rule.
Wetlands serve as a natural filtration system, Anne said. They’re providing an important service, and not just in water quality.
“There was a fear a few years ago that all these ponds would lead to a mosquito problem,” she said. There was concern about the spread of the West Nile Virus.
“A good healthy wetland is teeming with all these wonderful predators that are eating mosquitoes like crazy.”
She and Steve will continue their efforts to teach people about the value of a diverse range of organisms, from the tiny planaria to the dragonfly flitting past your head.
• Anne Coburn-Griffis leads volunteers on water quality monitoring projects along the Maumee River from May to October. For more information, call her office at 419/981-6319.
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