Curtis Pearlymussel (Epioblasma curtisi)
Status: Endangered; considered Extinct
June 14, 1976
For questions regarding the Curtis Pearlymussel, please contact Chris Davidson at firstname.lastname@example.org or 501-513-4481.
By the time the Curtis’ pearlymussel was listed, it had already disappeared from the White River in Missouri, where it was historically abundant. Other sites seemed stable until a catastrophic decline (average 77% decrease) of mussel fauna in the late 1980s. In 1993, one Curtis’ pearlymussel was discovered in 100 hours of search time in the Little Black River. That was the last observed in the wild. No extant locations are currently known.
The fish host is unknown, although most species in the genus utilize darter or sculpin species. Many Epioblasma infest host fish by means of “host trapping”, where females use a modified mantle to lure fish close enough to capture the head of the fish between the shells. The female then expels glochidia directly onto the fish and later releases it.
This very small mussel can be found in large creeks to medium rivers with good water quality. It is only found in Arkansas and Missouri. This mussel prefers riffles within transitional zones of clean streams and rivers. It buries itself in sand or gravel in shallow water. In Arkansas, this species once occurred in the Spring and South Spring Rivers, but has not been collected live or dead in over 20 years.
Why is it Endangered?
Habitat alteration is the principle threat to the Curtis’ pearlymussel throughout its historical range. Flowing water and a stable substrate are important habitat requirements, and steam impoundments, dredging and channelization have almost entirely eliminated these habitats in many of the rivers that hosted Curtis’ pearlymussel populations.
Decreased water quality also threatens the species, usually from anthropogenic land use, including sedimentation, water withdrawal, nutrient loading, and chemical runoff. The decline of the Little Black River population was suspected to be primarily caused by water quality degradation and channelization.
Missouri purchased the Mudpuppy Conservation Area in 1988, which surrounds the last know location of the Curtis’ pearlymussel. This reach of the Little Black River also was declared an outstanding resource water by the Missouri DNR, a classification which requires more stringent water quality standards.
For more information on Curtis' pearlymussel recovery, check out the Recovery Plan (1986) and 5-Year Review (2010).
Range in Arkansas: