Crayfish: Introduced Species in the Sonoran Desert

Crayfish have been introduced into riparian habitats in various parts of the world, including Southern Arizona.  In these places, crayfish may have been introduced either accidentally, or purposefully, in hopes of controlling aquatic weeds.  Two species of crayfish are now found in Arizona, Orcontectes virilis and Procambaus clarkii. (People, Land & Water)

Crayfish are damaging to riparian habitats. They are believed to prey on native fish, frog, and invertebrate species. They are also believed to be damaging to the animals and their habitat in that they disturb the river bottom, bringing up sediment, and increasing the turbidity of the water. This increase in murkiness of the water damages the habitat, in that aquatic plants can not grow as well with the decreased amount of light. Animals also have problems surviving in this situation.  (People, Land & Water)

This problem is further added to unknowingly by classes. Classes which are provided with crayfish for study in the classroom often release them afterwards.  This act, while it seems more kind and beneficial to the crayfish, is actually detrimental to the environment in which these animals are introduced.  School districts are working to end this program providing crayfish. 

For more information on this species:

"Bullfrogs: Introduced Predators in Southwestern Wetlands" 
        Philip Rosen and Cecil Schwalbe. 
        http://biology.usgs.gov/s+t/noframe/x188.htm 

"Exotic Crayfish Prey on Rare Southwestern Fishes" 
        People, Land & Water, July/August 2000
        http://www.usgs.gov/invasive_species/plw/crayfish.html 

Source:

"Exotic Crayfish Prey on Rare Southwestern Fishes." People, Land & Water. United States Geological Survey, July/August 2000.

Rosen, Philip and Cecil Schwalbe.  "Bullfrogs: Introduced Predators in Southwestern Wetlands." Our Living Resources.  US Department of the Interior, National Biological Service: 1995.