What's in Your Water?

What's in Your Water?

DASNR researchers dive into Oklahoma streams.

How did the macroinvertebrate cross the road?

The question may seem like a joke, but the researchers from Oklahoma State University’s entomology and plant pathology department are not delivering punchlines about these stream-dwelling insects.

Insects living in Oklahoma streams vary from worms to tiny, shrimplike organisms called amphipods, said Melissa Reed, an OSU entomology and plant DASNR researchers dive into Oklahoma streams pathology doctoral candidate and lead researcher on the effects of damaged culverts on aquatic insects.

“Macroinvertebrates are insects you can see with your naked eye,” Reed said.

She called these organisms “super-recyclers” in their ecosystems because they clean up organic debris like leaves that fall into streams.

“As we get into autumn and leaves fall into areas of water, something has to break them down,” said Wyatt Hoback, ow did the macroinvertebrate cross the road? an OSU assistant professor who oversees the research. “Aquatic insects perform that function.”

These organisms provide an abundance of essential services to the ecosystem, Reed said, but their help could become scarce in the future when streams are broken up by damaged and outdated infrastructure.

“When we have different types of road structures crossing the creeks, how does that impact the insects upstream and downstream?” Hoback asked.

Streams cross under roadways through a pipe or tinhorn structure, known as a culvert, which enables the streams to keep their flow steady, Hoback said.

However, these culverts are not always well managed and can be detrimental to the survival of the vital aquatic insects, Hoback added.

“Some of the culverts are open where the water can flow easily through, and some of them are in such bad shape they are working as a dam,” Reed said.

As leaves and debris fall into the streams, they are swept downstream by the flow of the water, and the invertebrates living in the streams break them down, Reed said. When culverts are damaged, leaves do not make it to the rest of the stream, she said, and the food supply for insects is cut off.

The damming of culverts causes banks to erode, widening the stream, creating a pseudo-pond and reducing water flow, Reed said. This occurrence minimizes oxygen levels vital to the survival of gill-breathing insects, she added.

“The insects breathe oxygen just like fish do,” Reed said. “So, the only insects that can live there are the ones coming to the surface to breathe air.”

If a stream’s population contains only these aquatic, oxygen-breathing insects, that is a sign of deteriorating water quality, Reed said.

The research question Reed asks is how the insects perform from upstream to downstream when their environment is interrupted. To answer this question, she observes two geologically different areas in Oklahoma.

Melissa Reed collects aquatic insects, like this dragonfly, from stream beds.

Photo by JoMarie Hickerson.

“I’m examining culverts in two stream systems in two ecoregions in Oklahoma,” Reed said. “The first one is up in the northern part of the state called the Flint Hills ecoregion. The second ecoregion is the Ozark Highlands.”

Reed researches these ecoregions because of the ever-changing landscapes from one end of Oklahoma to the other, she said. What holds true in the clear, cold waters of the Ozark region cannot be applied to the sandy, muddy-bottomed streams in the plains, she explained.

For the last two years, Reed has collected samples of macroinvertebrates from both regions, using a mesh net and a helping hand from entomology and plant pathology undergraduate students. Reed catalogs the types of insects she finds in each region.

Reed said the goal is to describe any population changes from upstream to downstream of the damaged culverts they use as their test sites. To do this, Reed and entomology and plant pathology undergraduate student Rayne Key distribute packets of leaves for the insects to breakdown, Reed said.

“We collect leaves that haven’t fallen yet from the trees at the sites,” Key said. “We put them in a little netted bag and tie them with zip ties on a concrete slab and put them back down in the river above and below the culverts.”

Once the packets are secure, the researchers leave them throughout the winter months until the following spring, Key said. The researchers then evaluate the pace of leaf breakdown and compare it to the corresponding leaf packet downstream to determine the productivity of populations according to culvert damage, she said.

The pair also spend time in stream beds collecting insects to compare population differences and monitor the aquatic to nonaquatic insect ratio, Reed said.

Once enough data is collected, they hope to take this information to people who design culverts, like civil engineers, and help them change the way the culverts are constructed, Reed said.

“My goal is to give this data to people who actually design these bridges to say, ‘Look, the research shows we need to make more open structures,’” Reed said. “Placing five tiny pipes under the bridge does not work. They clog up with gravel and the water is not moving through. The habitat, the insects and everything that depends on the macroinvertebrates are suffering.”

The problem lies in making people understand the aquatic insects’ importance to the ecosystem, Reed said.

Insects collected from two ecoregions in Oklahoma allow Melissa Reed to compare population densities between up and downstream.

Photo by JoMaire Hickerson

“Aquatic insects are really overlooked even in the entomology field, but they are important,” Reed said. “They’re a main source of food for many varieties of fish.”

Aquatic insects provide food directly to smaller fish, and indirectly provide protein to larger fish, Hoback said. If food sources are reduced, the fishermen of Oklahoma could notice the difference in popular species like bass, catfish, walleye and bluegill, he added.

"Without aquatic insects, we don’t have any fish. Wyatt Hoback have any fish,” Hoback said. “Fish lay eggs, and the eggs hatch into tiny fish. Then as they grow, they have to eat something bigger, but they’re not quite ready to eat fish. So, they eat the aquatic insects instead.”

Insects play dual roles in the ecosystem, possessing the titles of both pest and beneficial organism, Hoback said. More often, these organisms are cast with a shade of “ick-factor” without acknowledging their importance, he added.

“When you get in your car, you expect to be able to drive it,” Hoback said. “Even if the rest of the car is intact, if you are missing a part like a spark plug, it doesn’t go. That one component is what makes all the difference. That’s what insects are to the ecosystem.” With the help of Reed’s research, these little eco-sparkplugs can get clogged stream engines running efficiently again, she said.

By JoMarie Hickerson | Lawton, Oklahoma