Contact Us|Site Map

Ecoregion Description

View global map

Species Richness

# of Endemic Species


150: Teays - Old Ohio

Major Habitat Type:

temperate upland rivers


Text modified from Abell et al. 2000. Freshwater Ecoregions of North America: A Conservation Assessment. Island Press, Washington, DC, USA.


United States


Predominantly within the physiographic provinces of the Appalachian Plateau in the east, the Central Lowlands, and the Interior Low Plateau in the southwest, this ecoregion is defined largely by the watershed of the present day Ohio River. Three other provinces, the Ridge and Valley, Blue Ridge, and a small part of the Gulf Coastal Plain, occur here as well. In total, the ecoregion covers parts of ten states: Illinois, Indiana, Ohio, Kentucky, West Virginia, Tennessee, North Carolina, Virginia, Maryland, Pennsylvania, and New York.

Drainages flowing into:

The Ohio River originates in western Pennsylvania at the confluence of the Monongahela and Allegheny rivers. It flows 1570 km where it joins the Mississippi River in southern Illinois (Robison 1986).

The historic Teays River once followed the ancient course of the Ohio River prior to the last ice age. Before advancing glaciers blocked their flows, many of the rivers in the eastern part of the region, including the Allegheny and Monongahela, flowed northward into the Laurentian system that today is composed of the St. Lawrence River and its tributaries. Consequently, fishes that had been confined to the Hudson Bay and Laurentian System were displaced into the Old Ohio during glaciation (Burr & Page 1986).

Main rivers or other water bodies:

In addition to the Ohio River, other major rivers in this ecoregion include the Wabash in Indiana, the Green River and Kentucky River in Kentucky, the Scioto and Muskingum rivers in Ohio, the New River in West Virginia, and the Monongahela, Youghiogheny, and Allegheny rivers in Pennsylvania.


The region was more topographically diverse during the Pliocene than it is today due to glaciation that began in the Oligocene and ended during the Pleistocene. It was once dominated by rolling hills over much of the landscape, but today includes large areas of low relief in the formerly glaciated southern Central Lowlands. To the south and eastern edge of the ecoregion topography is more varied and includes the rugged relief of the Appalachian Plateau as well as the rolling hills of the Interior Low Plateau (Robison 1986).


This ecoregion has a humid continental climate, with large seasonal variance in temperatures (Köppen 1936). Summers are generally hot or very warm throughout most of the ecoregion.

Terrestrial Habitats:

Historically, much of this ecoregion was forested, including areas where rich soils were deposited by the last glaciers. The ecoregion is primarily characterized as deciduous broadleaf forests dominated by oak-hickory communities in the west and sugar maple (Acer saccharum) and beech (Fagus grandifolia) in the north. To the east lie Appalachian mixed mesophytic forests, which were once widespread and served as mesic refuges during drier glacial periods (Ricketts et al. 1999). Much of the lower, downstream portion of the ecoregion, which was not glaciated, includes an extension of the Mississippi alluvial plain, where bottomland hardwood forests and swamps were once common (U.S. Fish and Wildlife Service 1995).

Fish Fauna:

The Teays-Old Ohio ecoregion is considered globally outstanding due to the sheer numbers of aquatic species found within it. With over 225 native fish species, as well as abundant unionid mussels, crayfish, and native amphibians and aquatic reptiles, this ecoregion has one of the highest total number of species in North America. This high level of richness is derived principally from the diversity of upland and lowland habitats, and the presence of both glaciated and unglaciated areas (Burr & Page 1986).

Description of endemic fishes:

Endemism is moderately high in the ecoregion, and certain basins have markedly higher endemism than others. For instance, the upper Green River drainage has an endemic sucker and three endemic darters (Thoburnia atripinnis, Etheostoma barbouri, E. bellum, and E. rafinesquei), while the Wabash River has no endemics (Burr & Page 1986). Within the entire ecoregion, the endemic fish fauna includes minnow, catfish, cave springfish, chub, shiner, and darter, among others. Several of these endemics are also found in the Tennessee [152] and Cumberland [151] ecoregions to the south, but have such limited distributions that they can be considered endemic within this small region.

Other noteworthy aquatic biotic elements:

Fourteen percent of mussels, 47% of crayfish, and 5% of herpetofauna are endemic. Endemism in herpetofauna is limited to three species of salamanders: the Black Mountain salamander (Desmognathus welteri), West Virginia spring salamander (Gyrinophilus subterraneus), and streamside salamander (Ambystoma barbouri). Like some of the endemic fishes, the Black Mountain salamander has a restricted range that falls within the southeastern portion of this ecoregion and the northeastern part of the Tennessee-Cumberland. In general, the fauna of this ecoregion is more cosmopolitan than that of the Tennessee [152] and Cumberland [151] ecoregions.

A native Ohio River crayfish species known as the rusty crayfish (Orconectes rusticus) is of special interest. Much like the flathead catfish, this voracious predator has been introduced into numerous other rivers and streams across the United States, primarily by bait dealers. Evidence suggests that this crayfish generally threatens to eliminate native crayfishes wherever it is introduced (Clancy 1997; Taylor pers. comm.).

Ecological phenomena:

The Teays-Old Ohio ecoregion is considered globally outstanding for its extraordinary species richness (Abell et al. 2000), especially in fish (208 species) and mussels (122 species).

Justification for delineation:

Ecoregion boundaries are taken from Abell et al. (2000) and are based on subregions defined by Maxwell et al. (1995).


Abell, R., Olson, D., et al. (2000). "Freshwater ecoregions of North America" Washington, D.C.: Island Press.

Burr, B. M.,Page, L. M. (1986)"Zoogeography of fishes of the lower Ohio-upper Mississippi Basin" In Hocutt, C.H.;Wiley, E.O. (Ed.). The zoogeography of North American freshwater fishes. (pp. 287-324) New York, New York, USA: Wiley.

Clancy, P. (1997) "Feeling the pinch: The troubled plight of America's crayfish".The Nature Conservancy Magazine

Maxwell, J. R., Edwards, C. J., et al. (1995) "A hierarchical framework of aquatic ecological units in North America (Nearctic Zone)". St. Paul, MN. North Central Forest Experiment Station, USDA Forest Service.

Ricketts, Taylor H. Dinerstein Eric Olson David M. Loucks Colby J. (1999). "Terrestrial ecoregions of North America: A conservation assessment" Washington, D.C.: World Wildlife Fund.

Robison, H. W. (1986)"Zoogeographic implications of the Mississippi River Basin" In Hocutt, C.H.;Wiley, E.O. (Ed.). The zoogeography of North American freshwater fishes. (pp. 267-285) New York, New York, USA: Wiley.

The Nature Conservancy World Wildlife Fund
©WWF/TNC 2008 | Copyright Notice | Sponsors |Last updated: May 15, 2014