Ozark Highlands




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.


United States

Major Habitat Type

Temperate upland rivers

Drainages flowing into

This ecoregion drains the portion of the Arkansas River from the Ozark Highlands. The Arkansas is the second largest tributary of the Mississippi River.

Main rivers to other water bodies

The Ozark Highlands is largely defined by the watersheds of the middle portion of the Arkansas River and the White River, including its tributary the Black River. Other major rivers bordering the ecoregion include the Missouri to the north and the Mississippi to the east.



This ecoregion extends from southern Missouri into northern Arkansas. The Ozark Highlands ecoregion is part of the western Mississippi drainage but is distinctive because of its relative biogeographical isolation. It is a region of high gradient headwater streams surrounded by coastal plains and prairie.


The Ozarks form a deeply dissected plateau comprised of four physiographic sections – the Salem Plateau, Springfield Plateau, St. Francois Mountains and Boston Mountains. Topography ranges from gently rolling hills to rugged areas with steep escarpments and low mountains with elevations up to 925 m (TNC-OEAS 2003). Karst features such as sinkholes, springs and caves are common.

Freshwater habitats

The Ozark Highlands contain a diversity of freshwater habitats, including fens, sinkholes and springs, which feed the clear headwaters of larger, free-flowing streams (TNC-OEAS 2003). Many of these habitats served as refugia during periods of glacial maximas (Hocutt 1977).

Terrestrial habitats

Terrestrial habitats in the ecoregion range from tallgrass prairie to oak-hickory forest, oak-hickory-pine forest, and cedar glades (McNab & Avers 1994).

Description of endemic fishes

Geographic isolation and age have contributed to a high level of endemism in fish, crayfish and mussels, many of which are found in karst habitats and streams. The Ozarks contain 10 endemic fish species, including a number of darters, the Ozark shiner (Notropus ozarcanus), Ozark chub (Erimystax harryi), and two madtoms (Noturus albater and N. flavater) (TNC-OEAS 2003).

Justification for delineation

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


  • 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.
  • Laws, J. (1998). "Ozark caving: Cave Pod People"
  • McNab, W. H. and Avers, P. E. (1994) \Ecological subregions of the United States\ U.S. Forest Service, ECOMAP Team, WO-WSA-5. Online. http://www.fs.fed.us/land/pubs/ecoregions/index.html..
  • 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.
  • Starnes, W. C. and Etnier, D. A. (1986). "Drainage evolution and fish biogeography of the Tennessee and Cumberland rivers drainage realm" C. H. Hocutt and E. O. Wiley (Ed.) The zoogeography of North American freshwater fishes ( pp. 325-362 ) New York, New York, USA: Wiley.
  • 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.
  • 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.
  • Cross, F. B., R.L. Mayden and J.D. Stewart (1986). "Fishes in the western Mississippi drainage" C. H. Hocutt and E.O. Wiley (Ed.) The zoogeography of North American freshwater fishes ( pp. 363-412 ) New York, NY: John Wiley & Sons.
  • The Nature Conservancy - Ozarks Ecoregional Assessment Team (2003) \Ozarks Ecoregional Conservation Assessment\ Minneapolis, MN. The Nature Conservancy Midwestern Resource Office.