Critical habitat zones proposed to protect freshwater mussels

As the number of freshwater mussels continue to decline across North America, the U.S. Fish and Wildlife Service is seeking to designate critical habitat areas to protect the species.

The service is proposing 3,974 river miles of the Mississippi River be designated as a habitat zone for four species of mussels: the rayed bean, sheepnose, snuffbox and spectaclecase.

The critical habitat zone proposed in Iowa focus on the spectaclecase and sheepnose freshwater mussels and would run from the Quad Cities south to Keokuk.

Nick Utrup, a fish and wildlife biologist with the U.S. Fish and Wildlife Service, said critical habitat designations are “one tool in the species recovery toolbox.”

When a species is listed as threatened, “critical habitat can be designated so we know where to focus recovery efforts, or where to focus protective efforts,” Utrup said. “It really does help us identify some of the best areas for recovery.”

Kevin Roe, an associate professor of Natural Resource Ecology and Management at Iowa State University, said the designation could be a game-changer for the four mussel species.

“By designating critical habitat, … the U.S. Fish and Wild seeks to protect habitat that evidence indicates is essential for the survival and ultimately the recovery and delisting of these species,” Roe said in an email.

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If the rule is finalized, Roe said, any activities in the designated areas that use federal funding must coordinate with the Fish and Wildlife Service to minimize impact on the mussels.

“It is important for the public to understand that this designation does not apply to private property unless the activity is funded by or authorized by a federal agency,” Roe said.

About the mussels

The spectaclecase species are larger mussels that grow up to 9 inches long and can live up to 100 years old.

They once were found in 61 rivers and streams, but now inhabit 40 waterways, according to the Fish and Wildlife Service. The spectaclecase population has declined by an estimated 60 percent.

The sheepnose mussel — also known as bullhead or clear profit — reaches about 5 inches in length, have a thick, yellow-brown shell and typically live up to 30 years.

The sheepnose mussels once were found in 79 streams and rivers but are now found in only 22 waterways across 14 states, including Iowa.

According to the wildlife service, freshwater mussels are considered one “of nature’s “greatest filtration systems” because a single freshwater mussel can filter five to 10 gallons of water per day.

When mussel populations decline, it can prevent mussel’s host fish from migrating, cause excess sedimentation and spread invasive species, like zebra mussels.

In total, the Fish and Wildlife Service is proposing about 801 river miles of critical habitat for the sheepnose and roughly 1,143 river miles for the spectaclecase.

Utrup said mussel species live in “Goldilocks zones” in freshwater rivers and streams where they form in “depositional zones” protected by the currents in riverbeds.

“The mussel beds typically are on the on a certain portion of the stream that's sheltered a little bit but have a little bit of hydraulic flow so that keeps a nice flow over the bed,” Utrup said. “You don't typically find mussels in shifting sand or anything like that.”

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The critical habitat proposal includes sections of 16 other states — Alabama, Arkansas, Illinois, Indiana, Kentucky, Michigan, Minnesota, Mississippi, Missouri, New York, Ohio, Pennsylvania, Tennessee, Virginia, West Virginia and Wisconsin.

Utrup believes the proposed zone in Iowa is the only section within the Mississippi River itself. The zones in other states are in tributaries of the river.

Although the proposal is along Iowa’s eastern border, native mussels can be found elsewhere in the state, Roe said.

“The rivers draining to the Mississippi River contain the largest number of species, whereas those draining to the Missouri River tend to have fewer species,” he said.

Why the decline?

The critical habitat proposal comes as 70 percent of mussel species in North America are in decline, according to the Fish and Wildlife Service.

The decline in mussels is due to several factors, Roe said.

“A number of factors seem to have played a role in the decline of native mussels, including competition from non-native species (and) poor water quality,” Roe said.

Also “man-made structures, such as dams, affect the hydrology of the rivers in which they live and can prevent some mussel species from interacting with their host fishes, which is required for successful reproduction.”

Utrup said it was “tough” to decide which rivers and states to add to the Fish and Wildlife Service’s critical habitat proposal.

“More than half of those these mussel species are considered imperiled or in poor condition,” Utrup said. “These four mussel species are in particularly bad condition because of their limited numbers or because of limited locations where they occur.”

To qualify for the critical habitat proposal, Utrup said the juvenile mussels — those less than 5 years old — have to be present in each decade, for the last four decades

Out of the nearly 300 mussel species across the continent, 7 percent are extinct, 21 percent are listed as endangered and 40 percent are considered threatened.

This also comes as the Service proposed critical habitat for the endangered rusty patched bumble bee in November, which is in its public comment period now until Jan. 27.

The mussel designation proposal went live on the Federal Register’s website Dec. 13, with public comment running through Feb. 11.

Olivia Cohen covers energy and environment for The Gazette and is a corps member with Report for America, a national service program that places journalists in local newsrooms to report on under-covered issues.

Comments: olivia.cohen@thegazette.com

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