Percina crypta

The validity of this taxon has been questioned by Hayes and Piller (2018).

Small, reduced, and fragmented range in shoal and riffle habitats in the Chattahoochee and Flint River mainstems and a few tributary systems in Alabama and Georgia; known extant range comprises four disjunct areas separated by mainstem impoundments and altered river reaches.

This species is endemic to the Apalachicola River drainage and occurs in the Flint River system, Georgia, and the Chattahoochee River system, Alabama and Georgia (Freeman et al. 2008). Within the Flint River system, the species is known from the Flint River mainstem above and below the Fall Line (the boundary between Piedmont and Coastal Plain physiographic provinces), and in at least four tributary stream systems (Lazer Creek and Potato Creek in the Piedmont province, and Muckalee Creek and the Ichawaynochaway Creek system in the Coastal Plain province). Within the Chattahoochee River system, it is known from two broadly separated areas: (1) the upper portion of the system in Georgia, including the mainstem Chattahoochee River, Chestatee River, and Sautee Creek (all upstream from Lake Lanier and in the Blue Ridge province) and (2) the Uchee Creek system, an Alabama tributary that enters the Chattahoochee River in the Fall Line Hills district of the upper Coastal Plain (Couch et al. 1996, cited by Freeman et al. 2008).

This species is represented by several distinct occurrences (subpopulations) (see map in Freeman et al. 2008). The known extant range comprises four disjunct areas separated by mainstem impoundments and altered river reaches (Freeman et al. 2008).

Freeman et al. (2008) hypothesized that P. crypta historically occurred more widely in the Chattahoochee River mainstem, prior to the construction of 13 dams on the river beginning in the mid-nineteenth century (Couch et al. 1996), For example, construction of Buford Dam, which began operating in 1959, likely eliminated habitat for P. crypta in the Chattahoochee and Chestatee mainstems in what is now Lake Lanier (Freeman et al. 2008). This dam modified the thermal and hydrologic regime in the Chattahoochee River downstream from the dam (Collier et al. 1996, Couch et al. 1996). Pollutants originating in the Atlanta metropolitan area have also altered water quality in the Chattahoochee downstream from Buford Dam (Couch et al. 1996). Shoal habitat (rocky areas that are relatively shallow with swift velocities at base-flow discharges) exists in this reach of the river, but habitat quality for many species is impaired by altered water quality and hydrologic conditions (Freeman et al. 2008). Removal of rock shoals and reefs from the Chattahoochee and Flint rivers during the late 1800s and early 1900s (to improve river navigability for steamboats) may have removed habitat for P. crypta (Freeman et al. 2008).

Present threats primarily consist of effects of urbanization on stream hydrology and water quality, particularly in the northern Georgia mountains and in the vicinity of the Atlanta metropolitan area (Freeman et al. 2008). The Flint River headwaters originate in Atlanta, and population growth in that region is expected to place increasing demands on the river system for water supply and waste assimilation (Freeman et al. 2008). Similarly, human population growth in the Blue Ridge province of northern Georgia will affect water availability and quality in the Chattahoochee River headwaters (Freeman et al. 2008).

Warren et al. (2000) and Jelks et al. (2008) rated this species as "Vulnerable."