Ecoregion Description

136: Cuatro Cienegas

Major Habitat Type:

xeric freshwaters and endorheic (closed) basins

Author:

Salvador Contreras Balderas, Universidad Autónoma de Nuevo León. Additional text was modified from Abell et al. 2000. Freshwater Ecoregions of North America: A Conservation Assessment

Countries:

Mexico

Boundaries:

Cuatro Ciénegas is located in an intermontane valley in the Mexican state of Coahuila.

Drainages flowing into:

Geologically, this ecoregion forms an isolated valley, but flows artificially to Río Salado. 

Main rivers or other water bodies:

The ecoregion includes the former headwaters of the Río Salado de Nadadores.

Topography:

The ecoregion is located in an intermontane valley of the Sierra Madre Oriental, with elevations ranging between 750 and 2700 m above sea level.

Climate:

The climate is arid, with mean annual temperatures between 16-22 °C. Total precipitation is less than 200 mm annually.

Freshwater habitats:

Cuatro Ciénegas in Spanish means "four marshes" and describes an extensive network of geothermal springs, lakes, and streams. Over 500 posas (spring pools) have been counted in the ecoregion. Other aquatic habitats include several sub-drainages, marshes, rivers, saline lakes (locally called lagunas or playas), canals, and terminal lagoons.

Waters in Cuatro Ciénegas have a wide diversity of qualities, from thermal to cool springs, clear to turbid, fresh to saline to gypsum loaded. This has resulted in great habitat diversity among the springs, with extreme variation often within small spatial scales.

Terrestrial Habitats:

The ecoregion falls primarily within the Chihuahuan Desert, but supports vegetation not entirely typical of this desert ecoregion. Vegetation communities range from halophilic, aquatic, and semi-aquatic to grasslands, gypsum dune assemblages, scrub, chaparral, and pine-oak forests.

Fish Fauna:

The ecoregion contains relatively few species, although most of these are endemic. Non-endemic species include the flathead catfish (Pylodictis olivaris) and robust gambusia (Gambusia marshi).

Description of endemic fishes:

The diversity of habitats, stable ecosystems, and geographical isolation has resulted in a high level of endemism through adaptive radiation and speciation. Endemic species within the ecoregion include Minkley’s cichlid (Cichlasoma minckleyi), Cuatro Ciénegas shiner (Cyprinella xanthicara), Bolson pupfish (Cyprinodon atrorus), Cuatro Ciénegas pupfish (C. bifasciatus), Tufa darter (Etheostoma lugoi), Cuatro Ciénegas gambusia (Gambusia longispinis), Cuatro Ciénegas killifish (Lucania interioris), and northern platyfish (Xiphophorus gordoni). Minkley’s cichlid is particularly interesting because it exhibits two distinct morphs.

Other noteworthy aquatic biotic elements:

The ecoregion boasts over sixty species of amphibians and reptiles (including an endemic freshwater box turtle, Terrapene coahuila). Half of the crustacean species are endemic, as are two-thirds of the mollusks, and three-fourths of the snail species.

Ecological phenomena:

Waters in Cuatro Ciénegas have a wide diversity of qualities, from thermal to cool springs, clear to turbid, fresh to saline to gypsum loaded. This has resulted in great habitat diversity among the springs, with extreme variation often within small spatial scales.

Evolutionary phenomena:

Nearly all fish species are endemic within the ecoregion, some of them undescribed, or at least representing genetically significant populations. There are Neotropical and Nearctic related species, as well as some relict coastal related taxa. The peculiar nature of this highly endemic fish fauna extends to several plant and animal taxa.

Justification for delineation:

Ecoregion delineations were based on qualitative similarity/dissimilarity assessments of major basins, using the standard administrative hydrographical regions of the Mexican federal government. The delineation of this ecoregion was based on high levels of endemism among the flora and fauna, probably expressed in nearly 200 species, including some genera, where fishes are one of the most interesting. The fish fauna is derived from Lower Rio Grande/Río Bravo [135] ecoregion fauna, and most species are endemic due to the ecoregion’s isolation, water quality, and high occurrence of springs. The Neotropical species of characid, poeciliids, and cichlid are relict and, with other endemics in Río Pecos, related to more southern groups. In contrast, the Nearctic forms of cyprinids, ictalurids, centrarchids and percids are close to Rio Grande stocks.

Level of taxonomic exploration:

The ecoregion has been intensely studied, although it still harbors little known, undescribed, or unstudied taxa.

References/sources:

Abell, R. A., Olson, D. M., et al. (2000). "Freshwater Ecoregions of North America: A Conservation Assessment" Washington, DC, USA: Island Press.

Alcocer, J.,Kato, E. (2002)"Cuerpos acuáticos de Cuatro Ciénegas, Coahuila" In de-la-Lanza-Espino, G.;García-Calderón, J.L. (Ed.). Lagos y Presas de México. (pp. 269-286) México: AGT Editor.

Minckley, W. L. (1984). "Cuatro Ciénegas fishes: research review and a local test of diversity versus habitat size" J. Az. Nev. Acad. Sci. 19 13-21.

Minckley, W. L. (1969). "Enviroments of the Bolson of Cuatro Ciénegas, Coahuila, México, with special refeence to the aquatic biota" University of Texas at El Paso, Sci. Ser. 2 1-65.

Norris, S. M.,Minckley, W. L. (1997). "Two new species of Etheostoma (Osteichthys: Percidae) from central Coahuila, northern Mexico" Ichthyol. Explor. Freshwaters 8(2) 159 - 176.