PINK MUCKET - Lampsilis abrupta
The pink mucket is a rounded to slightly elongate mussel with a thick, inflated, smooth, yellowish-brown shell. They live in flowing waters of large streams among gravel and cobble. The principal cause of decline has been habitat alteration from dam construction, channelization, and dredging. The species is listed ENDANGERED by the Missouri Department of Conservation and ENDANGERED by the U.S. Fish and Wildlife Service.
Identification
The pink mucket is rounded to slightly elongated. The posterior end is bluntly pointed in males. Female pink muckets are shorter and may be nearly square. The shell is thick, inflated and smooth. Adult pink muckets are three to five inches long.
Growth-rest lines produce ridges and dark-stained grooves on the shell. The outer layer of the shell is yellowish-brown to chestnut-colored in mature individuals. Broad, faint, green rays may cover the shell but are usually absent from adult shells.
Beaks (raised structures located externally near the hinge of the shell) are slightly raised above the hinge line. Beak sculpture, which is often difficult to discern, consists of six to ten fine, wavy, double-looped bars. The teeth (located dorsally within the shell) are large and well developed. The shell's inner lining (nacre) is white to a light salmon or pink and commonly salmon to orange in the beak cavities.
Identification can be difficult for many freshwater mussel species and often requires verification by an expert.
For a technical description of this animal, refer to:
- Oesch, R.D. 1984. Missouri Naiades: a Guide to the Mussels of Missouri. Missouri Department of Conservation. Jefferson City, MO. 270 pp.
- Cummings, K.S. and C. A. Mayer. 1992. Field Guide to Freshwater Mussels of the Midwest. Illinois Natural History Survey Manual 5. Champaign, IL. 194 pp.
Life History
Freshwater mussels live on the bottom of streams or ponds. They move very little, depending on water current to bring them oxygen and food. Most species burrow into the bottom of the stream, leaving the posterior edge of the shell exposed to the current. If water quality is good they may live 20 to 30 years or more.
Reproduction is poorly understood for most species, but the general life cycle of the pink mucket is similar to other freshwater mussels. Under certain conditions (perhaps changes in water flow or water temperature) males release sperm directly into the water. Females living downstream siphon the sperm into the gill chamber where eggs are fertilized. The fertilized eggs then mature into larva (called glochidia), which eventually are discharged into the water when a host fish (or for one mussel species, a host mudpuppy) swims by. The pink mucket produces glochidia in September and releases them the following June. The host fish is an important part of mussel reproduction, for without the right species of host fish the tiny larval mussel will die. Depending on the species of mussel, the glochidia attaches to either the gills or to the fins or tail of the host fish. Each larval mussel must spend a few days or weeks attached to the host, where they transform to juvenile mussels. During that time they are parasites on the host fish. Eventually, this tiny mussel breaks away from the fish and floats to the bottom of the stream to begin growing into a free living mussel. Each mussel species only parasitizes certain species of fish. The host fish for the pink mucket is unknown.
Habitat and Distribution
The pink mucket occurs in Missouri, Illinois, Indiana, Arkansas, Alabama, West Virginia, Ohio, Pennsylvania, Virginia, Louisiana, Kentucky and Tennessee. They are found in the lower Mississippi and Ohio rivers and their larger tributaries.
In Missouri, the pink mucket lives primarily in the Meramec, Gasconade, and Black rivers, and stretches of the Osage River. Pink mucket shells have been found in the Sac, Big, St. Francis, and Little Black rivers; however, live pink muckets have not recently been found in these rivers.
Pink muckets live in the large stream reaches where flowing water covers beds of cobble, gravel and sand. The depth of the water can vary from one inch to five feet deep.
Cause of Historic Decline
The pink mucket appears to be a species that is wide ranging but often uncommon throughout its range. Habitat loss from dam construction, channelization, and dredging are the main reasons this species has declined. Deteriorating water quality and siltation also affects mussel populations.
Dams and channelization have not been a threat to this species in the Missouri portion of its range.
There has been habitat alteration from gravel dredging in some areas, but diminishing water quality is probably the greatest threat to current populations.
As the number of mussels declines, reproductive success may be limited by their low density in a stream.
Current Threats to Pink Mucket
- Loss of habitat and/or habitat alteration Dredging and in-stream sand and gravel mining are threats in the lower reaches of the Meramec, Osage and Gasconade rivers. These activities may kill small numbers of mussels, but more significantly, the substrate is disturbed and destablized.
- Habitat degradation Diminishing water quality is a concern for all aquatic species. It is not clear how much of an impact pesticides and agricultural runoff are having on pink muckets.
- Competition with exotic zebra mussels Zebra mussels are an introduced species that competes with native mussels for food and living space. Mortality linked to zebra mussel competition include starvation, loss of reproduction, depleted oxygen availability, and beaching after storms. Although they are not presently affecting pink muckets in Missouri, zebra mussels may eventually inhabit the same stretches of streams and affect native mussels.
- Overharvesting and illegal collecting Pink muckets have a commercial value for use in the polished chip industry. However, commercial mussel harvest is legal in only a few rivers in Missouri, none of which contain pink muckets.
Protection and Management: Steps Toward Recovery
There is little that individual landowners can do to assist in the recovery of this species. Protection and management of this species is clearly related to managing the habitat and water quality of the large rivers this species depends upon.
Support protection of rivers and streams. Report mussel poaching by calling Operation Game Thief or your local Conservation Agent.
- Habitat protection and improvement Landowners who own stream frontage should protect and manage streamside vegetation. Missourians interested in establishing a forested riparian corridor should take advantage of the Stream Incentive Program. Establishing a protected corridor along all streams is good fish and wildlife management whether there are endangered species present or not. Gravel removal and dredging operations in the lower reaches of streams inhabited by pink muckets must operate within gravel removal guidelines so that the impact to mussel beds is minimized. Procedures are outlined in Missouri Instream Sand and Gravel Removal Guidelines prepared by the Missouri Departments of Conservation and Natural Resources. For more information and a copy of the pamphlet, contact the Missouri Department of Conservation, Policy Coordination Section.
- Zebra mussel control Public education will slow the spread of zebra mussels. If their populations increase to the point that they threaten native mussels, resource agencies may have to remove freshwater mussels from streams and rear them in hatchery facilities until zebra mussel control is possible. Government agencies who protect our waterways and manage fish and wildlife have the primary responsibility to initiate actions to protect pink mucket populations.
Written by Charlene M. Bessken
Missouri and federal law prohibits the importation, transportation, sale, purchase, taking or possession of animals on the State or Federal lists.
For more information on the pink mucket, or to report sightings of this species, contact:
Endangered Species Coordinator or Wildlife Ecologist Missouri Department of Conservation Natural History Division P.O. Box 180 Jefferson City, MO 65102 573/ 751-4115
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