Text modified from Abell et al. 2000. Freshwater Ecoregions of North America: A Conservation Assessment. Island Press, Washington, DC, USA. Additional text provided by Jennifer Hales.
Major Habitat Type
Temperate upland rivers
Drainages flowing into
The Tennessee River is the largest tributary of the Ohio River, and drains the eastern side of the lower Mississippi Basin.
Main rivers to other water bodies
Originating in the Appalachian Highlands of Virginia, the Tennessee River drainage covers more than 103,600 km2 (Ono et al. 1983). Major tributaries to the Tennessee include the Clinch, Powell, Holston, French Broad, Duck, Elk, Buffalo, Bear Creek, Paint-Rock, Sequatchie, Little Tennessee, and Hiwassee rivers.
Although the Tennessee and Cumberland rivers flow quite close to each other near their confluence with the Ohio, they were not physically linked historically. Today, dam construction on both rivers has changed this situation. The construction of Barkley Dam impounded the Cumberland, forming Lake Barkley, while just a few miles away the Kentucky Dam was built to impound the Tennessee River, thereby creating Kentucky Lake. This alone was not enough to link the two reservoirs, so a channel was cut not far from the head of each lake to link them together. Other mainstem and tributary reservoirs constructed by the Tennessee Valley Authority for flood storage and power generation are also major surface water features.
The watershed of the Tennessee River, which drains to the larger Mississippi Basin, defines this ecoregion. The majority of this area is centered in Tennessee; the river also drains parts of southwestern Kentucky, southwestern Virginia, western North Carolina, two disjunct areas in northern Georgia, northern Alabama, and the extreme northeastern corner of Mississippi.
The topography of the ecoregion is varied, rising from the Coastal Plain in the west to the Blue Ridge Mountains in the east. Tributaries drain the southern portion of the Highland Rim province, an upland area between 250 – 300 m elevation that encircles the Nashville Basin. East of the Cumberland Plateau lies the Ridge and Valley province, which is characterized by northeast-southwest trending long, even ridges and valleys. The Blue Ridge Mountains run parallel to the Ridge and Valley to the east and drain the high basins (600 – 800 m) within the ecoregion, with headwaters reaching elevations up to 1700 m (Starnes & Etnier 1986).
From west to east, the Tennessee ecoregion traverses a number of physiographic provinces, creating a broad diversity of freshwater habitats. The lower Tennessee River basin drains a small portion of the coastal plain, and in this area streams are moderate to lower gradient. Swamps occur in the Big Sandy system, a major lower tributary to the Tennessee in the northwest corner of the ecoregion. Cave and spring habitats are abundant in the Highland Rim province, which covers most of the western half of the ecoregion. To the east of the Highland Rim is the Cumberland Plateau, and to the east of that is the Ridge and Valley province. Finally, the southeastern headwaters of the Tennessee drainage are found in the Blue Ridge province, where streams are typically high gradient and cold (Starnes & Etnier 1986).
Much of the ecoregion is covered in forest, particularly in the Jefferson, Pisgah, Cherokee, Nantahala, and Chattahoochee National Forests. Agriculture also accounts for a major land use, with most agricultural land used for pasture (Hampson 1995).
Description of endemic fishes
These endemics are made up of a large number of darters, as well as minnows, chubs, madtom catfishes, a cave-fish, pygmy sunfish and sculpins (Starnes & Etnier 1986). Of the many physiographic provinces in this ecoregion, the Highland Rim and Ridge and Valley tend to support the largest numbers of fish species. Many species with the most restricted ranges are found where provinces meet and overlap; for instance, the palezone shiner (Notropis sp.), smoky madtom (Noturus baileyi), and duskytail darter (Etheostoma sp.) all apparently require habitat created by the combination of features in two provinces (Starnes & Etnier 1986). New species of fish continue to be discovered and described in this ecoregion, despite fairly extensive historical study of the region’s fauna (Starnes & Etnier 1986; Burr pers. comm).
Justification for delineation
Ecoregion boundaries are modified from Abell et al. (2000), which based its units on subregions defined by Maxwell et al. (1995). Modifications to this ecoregion were made following recommendations from the Endangered Species Committee of the American Fisheries Society. Based on faunal data from Hocutt & Wiley (1986), the Endangered Species Committee decided there was a significant number of species exclusively endemic to the Cumberland  and Tennessee  drainages to warrant separate ecoregions.
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