Mussel "backpacks" help UI researchers study water quality

IOWA CITY — It may not seem that exciting to connect an electronic sensor to a slow-moving shellfish.

But University of Iowa researchers can learn a lot about water quality from tiny electronic “backpacks” glued to the shells of mussels that live in Iowa’s streams and rivers. The UI’s backpack sensors are the first to be wireless, so mussels can move freely – they use a muscular “foot” to pull themselves along – while transmitting valuable data.

“So far, what they do is measure gape, which is the opening and closing of the shell,” said Craig Just, a UI engineering professor. “I can see how much algae they will filter out of the river.”

Approximately 300 species of freshwater mussels live in North America, with nearly 50 of those found in Iowa and its border rivers, according to the Iowa Natural Heritage Foundation.

Mussels filter water by feeding on algae, protozoa and bacteria, which means the water is generally cleaner where mussels are located in large numbers.

But mussel populations have been decimated by pollution, dams and stream dredging. Just and his colleague, Anton Kruger, hope the data they collect from the mussel backpacks will help bolster the argument for more habitat restoration.

In his UI lab, Just attaches the backpacks to plain pocketbook mussels, which are about the size of a human hand and can live for decades. The backpacks, designed by Kruger, are contoured to the mussels’ shells and cost about $100 each.

For now, the pack-wearing mussels live in tanks filled with water straight from the Iowa River.

“It’s as close to the river environment as you can get,” Just said.

When the mussels go back to the natural environment, they likely will be kept in enclosures so researchers can remove the sensors when their batteries die after a few months, he said.

“We don’t want to be electronic litterers,” he said.

The project has received about $580,000 from the Carver Charitable Trust in Muscatine as well as matching grants from the UI. Researchers are seeking additional funding, Just said.

 Monitoring nitrate flow

As Iowa implements a new strategy for reducing harmful nitrates in waterways, Eastern Iowa scientists hope real-time data from high-resolution sensors can show what is – and isn’t – working.

Doug Schnoebelen, director of the Lucille A. Carver Mississippi Riverside Environmental Research Station north of Muscatine, plans to install 10 sensors in 2014 to collect nitrate data from eastern Iowa streams and rivers.

“If we can understand some of those watersheds better, we can do a better job managing those,” Schnoebelen said.

Nitrogen and phosphorus pollution primarily from agricultural sources has contributed to an oxygen-deprived “dead zone” in the Gulf of Mexico where fish and other aquatic life can’t survive.

The UI’s nitrate sensors are designed to take measurements every 20 minutes, which Schnoebelen would like to have transmitted via cell phone to computer servers at the UI.

The sensor packages, which cost about $35,000 a piece, were purchased several years ago through a Carver Charitable Trust grant.

The sensors are powered by solar panels, but they need occasional maintenance and cleaning. Schnoebelen is seeking funding for upkeep, or community partners willing to help with sensors near their towns.He plans to continue monitoring the lower Iowa River and Cedar River watershed and consider installing sensors on other watersheds including the Turkey River, Middle Raccoon, Upper Cedar/Soap Creek and Chequest Creek.

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