Tiny Shrimp is Newest Threat to Great Lakes

By Mike Lafferty, The Columbus Dispatch, Ohio

Mar. 18–A half-inch shrimp is the latest Great Lakes invader to make biologists nervous.

The bloody red shrimp, a native of southwestern Asia, has been discovered in Lakes Michigan and Ontario.

“I’d be looking in Lake Erie,” said Anthony Ricciardi, a Canadian aquatic biologist who predicted in 1998 that the shrimp, Hemimysis anomala, would hitch a ride to the Great Lakes in the ballast water of ships arriving from Europe.

The shrimp joins zebra and quagga mussels, round gobies, sea lampreys, Eurasian ruffe, spiny and fishhook water fleas and more than 180 other plant and animal invaders that are reworking Great Lakes biology.

Dave Culver, an aquatic biologist at Ohio State University, said the fear is that the bloody red shrimp will devastate the food supply of commercial fish, including the yellow perch.

While the bloody red shrimp is a source of food for adult fish, the invader also feeds on tiny animals called zooplankton, which many fish hatchlings eat to survive.

Many native populations eventually could be hammered, Culver said.

This happened several decades ago when a native species of shrimp was placed in western lakes to boost populations of trout and other fish.

“The results were remarkably successful for one or two years,” Culver said. “Then the shrimp ate all the food supplies, and the fish that depended on the native zooplankton declined.

“If you add a new food-chain level … it’s going to be a disaster.”

Steve Pothoven, a federal fisheries biologist, spotted the bloody red shrimp in November when he glanced over the side of a boat docked at the Great Lakes Environmental Research Laboratory on Lake Michigan and saw a red cloud.

“We know they’re going to be in harbor areas,” he said. “We want to look in the open lake of Lake Michigan also and try to determine whether they’re just along the shoreline.”

He said biologists should be doing the same in Erie.

Native shrimp live in cold, deep water, including places in Lake Erie between Cleveland and Erie, Pa.

Ricciardi said the new shrimp are more tolerant of warmer water, which could allow them to spread into shallow areas.

They’ve already proved adaptable. Native to the Caspian and Black seas, the shrimp have moved during the past two centuries into western Europe through rivers and canals.

When they arrived at harbors on the Atlantic and North Sea, the shrimp hitched rides to the Great Lakes — a lot of rides.

“One of the characteristics of a successful invader is, you have to increase population quickly,” Ricciardi said. “This is a big roulette-wheel spin. If you spin the wheel enough times, all things being equal, a new species will be established.”

mlafferty@dispatch.com

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Copyright (c) 2007, The Columbus Dispatch, Ohio

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