Species Diversity

The Cahaba River is one of Alabama’s most spectacular rivers in terms of species diversity. Unfortunately the basin is also unique in the number of aquatic species that are imperiled or declining in number. The Cahaba River Watershed supports 69 rare and imperiled species including 10 fish and mussels listed as threatened and endangered. (TNC)

American Rivers reported the Cahaba as one of the 10 most endangered rivers in North America. The Nature Conservancy ranks the Cahaba Watershed as the 29th most critical for protecting biodiversity out of 2000 total watersheds in the United States. They highlight the Cahaba as one of eight Hotspots of Biodiversity out of 2,111 watersheds nationwide.

The Cahaba River serves as an important refuge for numerous rare species including 32 plants, 23 molluscs, and 9 fishes. (Project and O’neil)

The Cahaba is the most icthyologically (refers to the study of fishes) diverse free-flowing river for its size in North America (Mayden ’89)

The middle and lower portions of the river support the greatest biodiversity. (State of Rivers)
FISH
The significance and scale of the Cahaba’s biodiversity is nowhere more apparent than in its variety of fish. No other river in North America has more species of fish per mile than the Cahaba River. With 131 different fish species, the river is a world champion of fish diversity. 18 of these fish are found nowhere else outside of the Mobile River Basin. (TNC and Keith)

3 of these species have received federal designation as threatened and endangered by the Endangered Species Act.

The Blue shiner (Cyprinella caerulea) is a threatened species with a historic range in the Cahaba River of approximately 60 miles. The last blue shiner collected in the Cahaba was found in 1971. This population is believed to be extirpated (a localized extinction) from the Cahaba basin. Sampling in the last decade has failed to locate any individuals.

cahaba fish
Cahaba shiner (Notropis cahabae)

The Cahaba shiner (Notropis cahabae) is anendangered species once thought to be endemic (to only occur) in a 76-mile stretch of the main river channel of the Cahaba. The remaining population in the Cahaba is limited to a 15-mile stretch of the main stem between the Fall Line and Bibb Co. Bridge 26. The fish was listed as endangered shortly after it was described in 1989. (Fishes & Project)

The Alabama Geological Survey recently discovered new populations of the Cahaba shiner in the Locust Fork River (Black Warrior Basin) in 1998 in approximately 60 river miles similar in character to the Cahaba. The Locust Fork population appears to be in equal or better condition relative to population size. (Fishes, Project)

Cahaba fish 2

The Goldline darter (Percina aurolineata) is athreatened species and the Cahaba provides its only remaining habitat in Alabama. Historically it occurred in 49 miles of the Cahaba mainstem, 7 miles of the Little Cahaba and Shultz Creek, a tributary to the Cahaba. Recent surveys found five sites between Centreville and Blue Girth Creek on the mainstem Cahaba, but dwindling populations in the Little Cahaba. In Georgia this species is found in the Coosawattee and associated tributaries of the upper Coosa basin.  The Goldline darter was listed as threatened on April 22, 1992. (Fishes)(FWS-register)(Project)

The Frecklebelly madtom (Noturus munitus) is a rare fish that is on the State of Alabama’s Protected list. Historically known from upstream of the Fall Line to Bridge Hwy 183 near Sprott. Currently most populations seem to be confined to below the Fall Line, with strong populations found at Cooper Island where there is an abundance of silt free gravel shoals.

Fish status in Cahaba River Basin
Total species 131
# threatened or endangered 3

(compiled from O’neil and others for the Cahaba River Basin Project)

MUSSELS
At one time, the Cahaba Basin boasted a significant diversity of freshwater mussel species. Historic surveys of the watershed identified 48 different species, a higher diversity than in all Europe (Haddock). Just thirty years later this diversity was reduced to 38 species. According to the most recent surveys, the Cahaba now harbors only 27 species, almost half of those species recorded. (Project, Haddock)

Of the 17 species of freshwater mussels recognized as endangered or threatened in the Mobile River Basin, 11 of these species (65%) historically occurred in the Cahaba River. Though many of these species are presumed to be extirpated (locally extinct) from the Cahaba Basin, some populations are still intact.

The Alabama Moccasinshell (Medionidus acutissimus) is a threatened species thought to be extirpated from the Cahaba Basin. This species was listed on the threatened/endangered species list on March 17, 1993.

The Coosa Moccasinshell (Medionidus parvulus) is an endangered species thought to be extirpated from the Cahaba Basin. This species was listed on the threatened/endangered species list on March 17, 1993.

The Fine-lined Pocketbook (Lampsilis altilis) is a threatened species. This species was listed on the threatened/endangered species list on March 17, 1993.

The Heavy Pigtoe (Pleurobema taitianum) is an endangered species thought to be extirpated from the Cahaba Basin. It is now thought to be limited to the Tombigbee Watershed Basin (the Sipsey River swamp). This species was listed on the threatened/endangered species list on April 7, 1987.

The Ovate Clubshell (Pleurobema perovatum) is an endangered species thought to be extirpated from the Cahaba Basin. This species was listed on the threatened/endangered species list on March 17, 1993.

The Upland Combshell (Epioblasma metastriata) is an endangered species thought to be extirpated from the Cahaba Basin. This species was listed on the threatened/endangered species list on March 17, 1993.

The Southern Acornshell (Epioblasma othcaloogensis) is an endangered species thought to be extirpated from the Cahaba Basin. This species was listed on the threatened/endangered species list on March 17, 1993.

The Southern Clubshell (Pleurobema decisum) is an endangered species thought to be extirpated from the Cahaba Basin. This species was listed on the threatened/endangered species list on March 17, 1993.

The Southern Combshell (Epioblasma penita) is an endangered species thought to be extirpated from the Cahaba Basin. It is now thought to be limited to the Tombigbee Watershed Basin (the Buttahatchee tributary). This species was listed on the threatened/endangered species list on April 7, 1987.

The Triangular Kidneyshell (Ptychobranchus greeni) is an endangered species. This species was listed on the threatened/endangered species list on March 17, 1993.

The Warrior Pigtoe (Pleurobema rubellum) is presumed extinct throughout all of its former ranges in the Cahaba River and elsewhere.

Mussel status in Cahaba River Basin

Total species 42
# extinct 1
# extirpated 8
# threatened or endangered 11
SNAILS

The Mobile Basin historically has the richest assortment of snails in the world, totaling 118 different species. Recent surveys of snails in the Cahaba failed to find eight species of snail species historically collected in the Cahaba and a decline in 24 other snail species. (Source)

cahaba species 2
Picture courtesy of Randy Haddock, Cahaba River Society
cahaba species
Picture courtesy of Randy Haddock, Cahaba River Society

4 species of aquatic snails are recognized as threatened or endangered in the Cahaba River system. (Corps).

The Cylindrical lioplax (Lioplax cyclostomaformis), an endangered species, is currently known only from approximately 15 miles of the Cahaba River above the Fall Line in Shelby and Bibb counties. (Bogan and Pierson). Historical records found this snail in the Coosa, Black Warrior and Alabama river drainages. All other populations outside of the Cahaba are believed to be extirpated. (Fed reg)

The Flat pebblesnail (Lepyrium showalteri), an endangered species, is currently known from one site on the Little Cahaba River, Bibb County, and from a single shoal series on the Cahaba River above the Fall Line in Shelby County. Historically this species was also found in the Coosa drainage. (Fed reg)

The Painted Rocksnail (Leptoxis taeniata), a threatened species.

The Round rocksnail (Leptoxis ampla), a threatened species, was historically found in the Cahaba and Coosa rivers and their tributaries. Its remaining habitat is limited to a series of shoals in the Cahaba River, in Bibb and Shelby counties, and from the lower reach of the Little Cahaba River, and the lower reaches of Shades and Six-mile creeks in Bibb County, Alabama (Fed reg).

The Cahaba pebblesnail (Clappia cahabaensis), was endemic to the Cahaba but is now thought to be extinct.

Snail status in Cahaba River Basin
Total species
# endemic
# extinct
# extirpated
# threatened or endangered 4
# imperiled
# special concern

PLANTS

32 plants found along the river are on the endangered or threatened species list (Keith).

One of the last refuges of the Shoals Lily, most commonly called the Cahaba Lily (Hymenocallis coronaria) is a stretch of the river not far from the town of West Blocton. The Cahaba lily (its bulbs lodged in the sandstone bottom of the main river channel) is recognized by its delicate white flowers which appear in May and June covering the river channel in a flow of blooms. The Cahaba lily is extremely rare in Alabama and across the Southeast. Its remaining range in Alabama occurs only in the Cahaba River, Hatchet Creek in the Coosa Basin, Mulberry and Locust Forks in the Black Warrior Basin, and a struggling population on the Tallapoosa River. Hargrove Shoals on the Cahaba is considered the largest remaining population of these rare lilies in the world. The lily is also pollinated by the nocturnal hawk moth. (Keith)

cahaba physical description
The Cahaba Lilies – Photo by Beth Young©

The Bibb County Glades adjacent to the Little Cahaba River recently revealed the presence of eight newly discovered species of plants found on limestone outcrops along the rivers banks. This discovery was made by botanist Jim Allison in 1992, and is of a scale practically unheard of in North America in this century. (TNC & Keith)

Nearby, a number of rare plants live in rural seclusion, amounting to the greatest concentration of rare plants in the Southeastern United States. If the nation wants an example of environmental diversity and wealth, it need look no further than the Cahaba River. (Keith)

OTHER

Little is known about the health and diversity of aquatic larval insects and other macroinvertebrates which provide a foundation to the food chain in most aquatic systems. However, one recent study identified 146 species of caddisflies in the Cahaba River, which is particularly rich compared to other Southeastern rivers. (Harris 84)

There are dozens of rare and endangered species found throughout the land area of the Cahaba River Watershed. Often their presence or declining presence is an indicator of changes in land use or the continuing fragmentation of natural habitat for these animals.

The Gray Bat (Myotis grisescens) is an endangered species known in about 40 cave systems in Alabama. Gray Bats often roost in caves in close proximity to large bodies of water due to improved foraging conditions. There is one well known population of Gray Bats in a cave adjacent to Lake Purdy on lands owned and managed by the Birmingham Water Works. (Project)

The Indiana Bat (Myotis sodalis) is an endangered species and covers a wider range than the Gray Bat.

The Wood Stork (Mycteria Americana) an endangered species, sometimes ranges into the Cahaba River Basin in summer after their breeding season.

The alligator snapping turtle (Macroclemys temminckii) and the black-knobbed sawback (Graptemys nigrinoda) are being carefully monitored by Alabama’s Natural Heritage Program to assess their level of imperilment.

CRAYFISH

CAHABA CRAUFISH
Photo of a Cahaba Crayfish by Randy Haddock