Teays - Old Ohio
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 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 to 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.
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.
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).
The ecoregion’s name is derived from the historic Teays River and 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. In contrast, much of the lower, downstream portion of the ecoregion, which was not glaciated, includes an extension of the Mississippi alluvial plain. This diversity of upland and lowland habitats and the presence of both glaciated and unglaciated areas resulted in an incredible diversity of aquatic species (Burr & Page 1986).
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). Bottomland hardwood forests and swamps were once common in the lower, unglaciated, portion of the ecoregion (U.S. Fish and Wildlife Service 1995).
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  and Cumberland  ecoregions to the south, but have such limited distributions that they can be considered endemic within this small region.
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.,Dinerstein, E.,Hurley, P. T.,Diggs, J. T.,Eichbaum, W.,Walters, S.,Wettengel, W.,Allnutt, T.,Loucks, C. J.;Hedao, P. (2000). "Freshwater ecoregions of North America" Washington, D.C.: Island Press.
- Burr, B. M. and Page, L. M. (1986). "Zoogeography of fishes of the lower Ohio-upper Mississippi Basin" C. H. Hocutt and E. O. Wiley (Ed.) The zoogeography of North American freshwater fishes ( pp. 287-324 ) New York, New York, USA: John Wiley & Sons.
- Clancy, P. (1997) \Feeling the pinch: The troubled plight of America's crayfish\ The Nature Conservancy Magazine>
- Ricketts, T. H.,E. Dinerstein,D.M Olson;C.J. Loucks (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" C. H. Hocutt and E. O. Wiley (Ed.) The zoogeography of North American freshwater fishes ( pp. 267-285 ) New York, New York, USA: Wiley.
- Maxwell, J. R., Edwards, C. J., Jensen, M. E., 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.
- Köppen, W. (1936). "Das geographische System der Klimate" Köppen W. and R. Geiger (Ed.) Handbuch der. Klimatologie ( (Vol. 1, pp. 1–44 ) Berlin, Germany: Gebrüder Borntröger.
- U.S. Fish and Wildlife Service (1995) \Strategic plan for conservation of Fish and Wildlife Service trust resources in the Ohio River Valley ecosystem. USFWS Regions 5, 4, and 3\ Ohio River Valley Ecosystem Team.