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Two tan colored mussels with dark striations eminating from their base on rocky substrate
Information icon Tan riffleshells, male on the left; female on the right. Public domain photo by Dick Biggins.

Tan riffleshell

Epioblasma florentina walkeri

The tan riffleshell (Epioblasma florentina walkeri) is a medium-sized freshwater mussel that is native to freshwater systems in the Southeastern United States. Historically, this species was much wider-ranging with populations in Alabama, Kentucky, Louisiana, Mississippi, North Carolina, Tennessee, and Virginia. However, after the tan riffleshell experienced a rapid decline, the population range was reduced to only a few freshwater systems in the U.S. (Indian Creek, Virginia and two rivers in eastern Tennessee). Subsequently, it was listed as endangered in 1977. Since then, conservation efforts have been designed to recover this imperiled species. Some methods of restoration include in vitro propagation, infesting host fish with mussel larvae (glochidia), releasing various ages/sizes of riffleshell into the water systems, etc. Recovery of the tan riffleshell is critical to our freshwater ecosystems, as mussels continue to be our primary indicator of favorable water conditions.

Appearance

The mussel’s dull brownish/yellowish-green shell surface has evenly distributed faint green rays. The subinflated valves are of unequal length and are marked with uneven growth rings. The inside shell coloring is bluish-white.

A mussel sample showing the inner and outer shell. The outer shell is tan with striations; the inner shell is pearl colored with a black marker identifying the sample
Tan riffleshell from the National Conservation Training Center teaching collection. Photo by Matthew Patterson, USFWS.

Habitat

Sedentary within the substrate (relatively silt-free substrates of sand, gravel, and cobble in good flows of smaller streams) of river systems.

Diet

Suspension feeder on plankton, algae, detritus, microbes; deposit feeder on bacteria and organic matter in substrate.

Historical range

This species’ historical range included Alabama, Kentucky, North Carolina, Tennessee, and Virginia.

Current range

The tan riffleshell is known to occur in Indian Creek, Virginia and suspected in two rivers in east Tennessee.

Conservation challenges

Construction of dams, increase of siltation, strip mining, agricultural practices, poor water quality, etc., pose challenges for conservation efforts of this species.

Recovery plan

Download the 1984 recovery plan.

Partnerships, research and projects

The Kentucky Department of Fish and Wildlife Resources Center for Mollusk Conservation culture the tan riffleshell at their facility in Frankfort, Kentucky. Once they have grown for a few weeks they are brought to Wolf Creek National Fish Hatchery where they are then placed in cages built specifically for mussel propagation. These cages are placed in floating racks in Lake Cumberland where they will reside for one to two growing seasons (April to October). Staff at Wolf Creek monitor cages weekly brushing off excess algae to promote optimal food flow through. Once the juveniles have been deemed large enough they are released back to their natural habitat.

How you can help

You can help by participating in individual or locally organized efforts to keep waterways, river systems, and ecosystems free of pollution, trash, and obstructions. Donations of time and/or money are sometimes accepted and encouraged through organizational groups that assist in implementing these propagation efforts for certain threatened and endangered species.

Public education is a simple way to improve the recovery of imperiled species. Spreading the word about population reductions, efforts of conservation for those species, and methods/necessities involved in assisting those efforts is a vital way to contribute to the restoration of any species in question.

Subject matter experts

  • Monte McGregor, Malacologist, Kentucky Department of Fish & Wildlife Resources, Monte.McGregor@ky.gov, (502) 573-0330 x221

Federal Register notices

The following Federal Register documents were automatically gathered by searching the Federal Register Official API with this species’ scientific name ordered by relevance. You can conduct your own search on the Federal Register website.

  • We're sorry but an error occurred. Visit the Federal Register to conduct your own search.

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