Arkansas fatmucket
Encyclopedia
Lampsilis powellii is a rare species of freshwater
mussel
known by the common name Arkansas fatmucket. It is endemic to Arkansas
in the United States, where it occurs in the Ouachita
, Saline
, and Caddo River
systems. It is one of two mussels endemic to Arksansas, the other being speckled pocketbook (Lampsilis streckeri). It is a federally listed threatened species of the United States.
This mussel, a bivalve mollusc
in family Unionidae
, is oblong oval in shape and can reach over 10 centimeters in length. The shell is brownish to olive green to tawny
in color on the outside and iridescent
bluish white on the inner surface. The back end of the shell of the male is pointed and that of the female is rounded.
The mussel occurs in deep pools with enough water flow to remove debris, but it does not occur in riffle
s or impounded pools that lack water flow. The substrate is sand, sometimes with rocks and gravel. It often lives next to river islands with stands of water willow
(Justicia americana) in water about a meter deep.
During breeding the male releases sperm and the female siphons it from the water. The fertilized eggs remain in the gills of the female. The glochidia
, the larvae of the mussel, are released into the water and attach to a host, which is a fish. The flap of the adult's mantle resembles a small fish and apparently attracts larger fish close enough for the glochidia to reach them. In a cyst on the fish they undergo metamorphosis to become juvenile mussels and then drop to the substrate to develop further.
This mussel is threatened by a number of processes. The rivers it inhabits have been impounded by dams at a number of locations, forming lakes and reservoirs including Lake Ouachita
, Lake Hamilton and Lake Catherine
. The rivers have been channelized and dredged. They have undergone increased sedimentation
and the flow rates have decreased enough that the sediment is not removed. Water quality has decreased because of runoff from barite
mining on the Caddo River and bauxite
mining on the Saline, and wastewater on a tributary of the Ouachita. Other sources of runoff include timber operations, roads, and feedlot
s. Most of the land in these river basins is used for silviculture
.
Freshwater bivalve
Freshwater bivalves are one kind of freshwater molluscs. They are bivalves which live in freshwater, as opposed to saltwater. Although the majority of species of bivalve molluscs live in the sea, a number of different families of bivalves live in freshwater...
mussel
Mussel
The common name mussel is used for members of several families of clams or bivalvia mollusca, from saltwater and freshwater habitats. These groups have in common a shell whose outline is elongated and asymmetrical compared with other edible clams, which are often more or less rounded or oval.The...
known by the common name Arkansas fatmucket. It is endemic to Arkansas
Arkansas
Arkansas is a state located in the southern region of the United States. Its name is an Algonquian name of the Quapaw Indians. Arkansas shares borders with six states , and its eastern border is largely defined by the Mississippi River...
in the United States, where it occurs in the Ouachita
Ouachita River
The Ouachita River is a river that runs south and east through the U.S. states of Arkansas and Louisiana, joining the Tensas River to form the Black River near Jonesville, Louisiana.-Course:...
, Saline
Saline River (Ouachita River)
The Saline River is a tributary of the Ouachita River in the south central portion of the U.S. state of Arkansas.The Saline River begins in the eastern foothills of the Ouachita Mountains in Saline and Garland counties and is one of the last free-flowing rivers in the Ouachita River Basin...
, and Caddo River
Caddo River
The Caddo River is a tributary of the Ouachita River in the U.S. state of Arkansas. The river is about long altogther.-Course:The Caddo River flows out of the Ouachita Mountains through Montgomery, Pike, and Clark counties in Arkansas before flowing into DeGray Lake and then to its terminus at the...
systems. It is one of two mussels endemic to Arksansas, the other being speckled pocketbook (Lampsilis streckeri). It is a federally listed threatened species of the United States.
This mussel, a bivalve mollusc
Bivalvia
Bivalvia is a taxonomic class of marine and freshwater molluscs. This class includes clams, oysters, mussels, scallops, and many other families of molluscs that have two hinged shells...
in family Unionidae
Unionidae
Unionidae is a family of freshwater mussels, the largest in the order Unionoida, the bivalve mollusks sometimes known as river mussels, naiads, or simply as unionids.The range of distribution for this family is world-wide...
, is oblong oval in shape and can reach over 10 centimeters in length. The shell is brownish to olive green to tawny
Tawny (color)
Tawny is a yellowish brown color. The word means "tan-colored," from Anglo-Norman tauné "associated with the brownish-yellow of tanned leather," from Old French tané "to tan hides," from Medieval Latin tannare, from tannum "crushed oak bark," used in tanning leather, probably from a Celtic source...
in color on the outside and iridescent
Iridescence
Iridescence is generally known as the property of certain surfaces which appear to change color as the angle of view or the angle of illumination changes...
bluish white on the inner surface. The back end of the shell of the male is pointed and that of the female is rounded.
The mussel occurs in deep pools with enough water flow to remove debris, but it does not occur in riffle
Riffle
A Riffle is a short, relatively shallow and coarse-bedded length of stream over which the stream flows at higher velocity and higher turbulence than it normally does in comparison to a pool....
s or impounded pools that lack water flow. The substrate is sand, sometimes with rocks and gravel. It often lives next to river islands with stands of water willow
Justicia americana
American Water-willow is a herbaceous, aquatic flowering plant in the Acanthus family native to North America. It is the hardiest species in the genus Justicia, the other members of which being largely tropical and subtropical, and it is able to survive as far north as USDA zone 4...
(Justicia americana) in water about a meter deep.
During breeding the male releases sperm and the female siphons it from the water. The fertilized eggs remain in the gills of the female. The glochidia
Glochidium
The glochidium is a special microscopic larval stage of larger freshwater mussels, aquatic bivalve mollusks in the families Unionidae and Margaritiferidae, the river mussels and European freshwater pearl mussels....
, the larvae of the mussel, are released into the water and attach to a host, which is a fish. The flap of the adult's mantle resembles a small fish and apparently attracts larger fish close enough for the glochidia to reach them. In a cyst on the fish they undergo metamorphosis to become juvenile mussels and then drop to the substrate to develop further.
This mussel is threatened by a number of processes. The rivers it inhabits have been impounded by dams at a number of locations, forming lakes and reservoirs including Lake Ouachita
Lake Ouachita
Lake Ouachita is a reservoir created by the damming of the Ouachita River by Blakely Mountain Dam . The lake is located near Hot Springs, Arkansas. Lake Ouachita is the largest lake completely in Arkansas, as the larger Bull Shoals Lake extends into Missouri. Lake Ouachita has over of shoreline...
, Lake Hamilton and Lake Catherine
Lake Hamilton and Lake Catherine
Lake Hamilton and Lake Catherine are a pair of man-made lakes around Hot Springs, Arkansas. The two lakes have greatly improved the tourism in Hot Springs. Both Lakes were created by Arkansas Power & Light .-Lake Hamilton:...
. The rivers have been channelized and dredged. They have undergone increased sedimentation
Sedimentation
Sedimentation is the tendency for particles in suspension to settle out of the fluid in which they are entrained, and come to rest against a barrier. This is due to their motion through the fluid in response to the forces acting on them: these forces can be due to gravity, centrifugal acceleration...
and the flow rates have decreased enough that the sediment is not removed. Water quality has decreased because of runoff from barite
Barite
Baryte, or barite, is a mineral consisting of barium sulfate. The baryte group consists of baryte, celestine, anglesite and anhydrite. Baryte itself is generally white or colorless, and is the main source of barium...
mining on the Caddo River and bauxite
Bauxite
Bauxite is an aluminium ore and is the main source of aluminium. This form of rock consists mostly of the minerals gibbsite Al3, boehmite γ-AlO, and diaspore α-AlO, in a mixture with the two iron oxides goethite and hematite, the clay mineral kaolinite, and small amounts of anatase TiO2...
mining on the Saline, and wastewater on a tributary of the Ouachita. Other sources of runoff include timber operations, roads, and feedlot
Feedlot
A feedlot or feedyard is a type of animal feeding operation which is used in factory farming for finishing livestock, notably beef cattle, but also swine, horses, sheep, turkeys, chickens or ducks, prior to slaughter. Large beef feedlots are called Concentrated Animal Feeding Operations . They...
s. Most of the land in these river basins is used for silviculture
Silviculture
Silviculture is the practice of controlling the establishment, growth, composition, health, and quality of forests to meet diverse needs and values. The name comes from the Latin silvi- + culture...
.
External links
- Bogan, A. E. 1996. Lampsilis powellii. 2011 IUCN Red List of Threatened Species. Downloaded on 12 September 2011.