Researchers from the Iowa Department of Natural Resources say they may have found an endangered species of mussel in the Iowa River.

Officials are testing DNA to determine if what they found is an endangered Higgins eye mussel or a Hickory Nut mussel, which looks similar to the Higgins eye.

“They are 80 percent positive it is [the Higgins eye],” said Natural Resources research biologist Paul Sleeper. “They have to make absolutely sure.”

But Natural Resources fisheries expert Scott Gritters said the study — which was conducted between Iowa City and Hills on Aug. 20 — has yet to be completed because of the high river levels.

Researchers didn’t have any technical tools to check for the mussels, which can be up to 4 inches long, forcing them to reach into the river with their hands.

“It is still a needle in a haystack finding these mussels,” Gritters said, and the difficulty of locating the creatures makes the find significant.

The potential discovery would be important because of the animal’s rarity and because the samples survived the floodwaters of last summer, Sleeper said.

The flood had devastating effects on the Iowa River’s ecosystem, he said. Because of the fast and powerful current, animals such as mussels can be swept away to other parts of the river, and sometimes land on firm ground.

Floodwater also transports large quantities of sand and silt, which can cover areas with rocky bottoms. These areas are usually home to small animals, which in turn feed the larger fish that mussels depend on to reproduce.

After a female Higgins eye takes in sperm from male mussels upstream, it forms an egg sac protuberance called “palps,” which Gritters said imitates a wounded guppy, enticing host-fish like the walleye and small mouth bass.

“The fish bites, and the young mussels blow up in the face in the fish,” he said.

The larvae live on the fishs’ gills for weeks or months, Gritters said, which distributes them through the river.

And if DNA testing confirms the species discovered in the Iowa River is a Higgins eye mussel, it could mean that a previous project by the Natural Resources was successful.

In 2001, the state Natural Resources sought to bring about a resurgence in the Higgins eye by taking advantage of their unique life cycle. Natural Resources employees stocked the Iowa River with host fish already containing the mussel’s larvae.

The existence of Higgins eyes is important because the mussels are indicators of a healthy ecosystem within the river, Gritters said, noting they would be the first animal to suffer from adverse river conditions.

“A lot of people think they are just a simple little animal, but they are really complex,” he said.