ABSTRACT

Size

25-30 mm SL as adults, rarely >40 mm

Conservation Status

Listed as Threatened by the Mexican Government in 1994.

Distribution

Restricted to saline lakes and pools, marshes and non-thermal springs and their outflows throughout much of the Cuatro Ciénegas basin, Coahuila, México.

Abundance

Common to remarkably abundant in restricted, local areas.

Habitat & Ecology

Coahuilan pupfish occupy habitats varying from hypersaline (to >95 gm/l, and higher), seasonally hot, shallow and otherwise severe lakes and pools through marshlands to quiet, non-thermal springheads. Little daily or seasonal movements occur at water temperatures of < 15°C, when different sexes and sizes of fish intermingle in loose aggregations. At temperatures < 10°C most individuals are dormant, on or within the substrate or within clumps of algae or other vegetation. Maximum temperature known to be tolerated in nature is 47.2°C; no living fish were present at 48°C. Feeding, breeding and other activities are most pronounced between 25 and 45°C when males form territories. Males and females remain strongly segregated except at times of actual breeding. They rarely live in water >25 cm, despite presence of far deeper places at some locales (e.g., springheads), and are characteristically in water < 5.0 cm deep. They associate with soft, flocculent, algae-rich bottoms, from which they feed on detritus, algae and small invertebrates.

Reproduction

Male Coahuilan pupfish tend to set up territories in exceedingly shallow water, usually < 5.0 cm, and may be solitary or in small, loosely aggregated leks. Territory size, levels of defensive posturing and activity and even spawning display vary with habitat, being far less developed in areas of dense vegetation or other high heterogeneity. A female enters a territory quickly to be confronted by the male, dips to the bottom with the male, spawns, hesitates, then moves to spawn again or rapidly away. Eggs hatch in a few days and young feed throughout the habitat, and with impunity within territories . Growth is rapid, to sexual maturity in a few weeks at summer temperatures.

Threats

Reduced volumes of flow during drought result in vast losses of shallow, marginal Coahuilan pupfish habitats. Some springs have further been canalized resulting in reduced water levels and in some instances desiccation, both of springheads and downflow marshes. In both cases, these pupfish are forced into channels (or canals) and thus into contact with Cuatro Ciénegas pupfish (Cyprinodon bifasciatus), the latter living almost exclusively in stable, thermal springs, moving downstream in summer in natural outflows and canals. Coahuilan and Cuatro Ciénegas pupfishes hybridize extensively under such conditions. Reduced spring discharge also results in diminution of marshes, bringing the preferred and required habitats of the two species into greater proximity and increasing the probabilities for introgression. Extraction of groundwater within and adjacent to springs exacerbates these conditions. As with other Cuatro Ciénegas fishes, non-indigenous crayfish, molluscs, and perhaps fishes (none yet confirmed as naturalized) may be anticipated to result in ecosystem-level changes that will influence the species in the future.

Conservation Actions

A substantial proportion of the Cuatro Ciénegas basin, including many springs their outflow channels, and other habitats inhabited by this pupfish, were set aside in 1994 as a biological preserve. Specific conservation actions are, however, yet to be proposed or implemented.

Conservation Recommendations

Important References

• Arnold, E. T. 1972. Behavioral ecology of two pupfishes (Cyprinodontidae, genus Cyprinodon) from northern México. Ph.D. Dissertation, Arizona State University, Tempe.
• ______. 1983. Pupfishes (genus Cyprinodon) of Cuatro Ciénegas: Hybridization in an intermediate habitat. Proceedings of the Desert Fishes Council. 5(1972): 114 (abstr.).
• Deacon, J. E. & W. L. Minckley. 1974. Desert Fishes. Pp. 385-488, in G. W. Brown, Jr. (ed.). Desert Biology: Special Topics on the Physical and Biological Aspects of Arid Regions. Academic Press, Inc., New York & London.
• Itzkowitz, Murray. 1968. Courtship and spawning in a pupfish (genus Cyprinodon) from Coahuila, México. M.S Thesis, Arizona State University, Tempe.
• _______ & W. L. Minckley. 1969. Qualitative behavior of a pupfish (Cyprinodon atrorus) in differing environments. Great Basin Naturalist. 29: 169-180.
• Miller, R. R. 1968. Two new species of the genus Cyprinodon from the Cuatro Ciénegas basin, Coahuila, México. Occasional Papers of the University of Michigan, Museum of Zoology. 659: 1-15.
• ______. 1978. Composition and derivation of the native fish fauna of the Chihuahuan Desert region. Pp. 365-382, in R. H. Wauer & D. Riskind (eds.). Transactions of the Symposium of the Biological Resources of the Chihuahuan Desert Region, United States and México. US National Parks Service Transactions and Proceedings Series. 3(1977). US Government Printing Office, Washington, DC.
• ______. 1981. Coevolution of deserts and pupfishes (genus Cyprinodon) in the American Southwest. Pp. 39-94, in R. J. Naiman & D. J. Soltz (eds.). Fishes in North American Deserts. John Wiley & Sons, NY.
• Minckley, W. L. 1969. Environments of the Bolsón of Cuatro Ciénegas, Coahuila, México, with special reference to the aquatic biota. Texas Western Press, University of Texas El Paso Science Series. 2: 1-65.
• ______. 1978. Endemic fishes of the Cuatro Ciénegas basin, Coahuila, México. Pp. 383-404, in R. H. Wauer & D. Riskind (eds.). Symposium on the Biological Resources of the Chihuahuan Desert Region, United States and México. US National Parks Service Transactions and Proceedings Series. 3(1977). US Government Printing Office, Washington, DC.
• ______. 1992. Three decades near Cuatro Ciénegas, México: Photographic documentation and a plea for area conservation. Pp. 81-110, in M. R. Sommerfeld & D. M. Kubly (eds.). Limnology and Aquatic Biology of the Southwest, Proceedings of a Special Symposium to Honor Professor Gerald Ainsworth Cole. 34th Annual Meeting of the Arizona-Nevada Academy of Science, Tempe, AZ, 21 April 1990. Journal of the Arizona-Nevada Academy of Science. 26(2).
• ______. 1994. A bibliography for natural history of the Cuatro Ciénegas basin and environs, Coahuila, México. Proceedings of the Desert Fishes Council. 25(1993): 47-64.
• Secretaria de Desarrollo Social. 1994. Decrito por elque se declara como Area Natural Protegida, con el carácter de Area de Protección de flora y fauna, la región conocida como "Cuatrociénegas", con una superficie de 84,347-47-00 Has. ubicada en el Municipio de Cuatrociénegas, Estado de Coahuila. Diario Oficial De La Federación, México, CDXCIV. 5-11.
• Secretaria de Desarrollo Social. 1994. Norma Oficial Mexicana NOM-059-ECOL-1994, que determina las especies y subspecies de flora y fauna silvestres y acuáticas en peligro de extinción, amenazadas, raras y sujetas a protección especial, y que establece especificaciones para su protección. Diario Oficial De La Federación, México, CDLXXVIII. 2-60.
• Williams, J. E., Bowman, D. B., Brooks, J. E., Echelle, A. A., Edwards, R. J., Hendrickson, D. A. & Landye J. J. 1989. Fishes of North American endangered, threatened, or of special concern: 1989. Fisheries. (Bethesda, MD) 14(6): 12-20.

Preparator

W. L. Minckley, Department of Zoology, Arizona State University, Tempe, Arizona 85287-1501

Referencias Importantes