Statistical Modelling Methodology for the Determination of Habitat Suitabilityand Habitat Preferences of the Endangered Fountain Darter

摘要

The San Marcos and Comal Rivers, located in south Texas, support populations offive Federally listed or endangered species. Both rivers are fed by spring runs which are supplied by the Edwards aquifer which is currently in an overdraft condition. A major reduction or elimination of spring flows is considered a severe threat to the survival of these species. In order to preserve these species, the United States Fish and Wildlife Service (USFWS) initiated a 5-year cooperative agreement with Utah State University to assess and quantify the instream flows necessary to protect these species. The research presented in this paper concentrates on the habitat needs and habitat utilization patterns of the fountain darter (Etheostoma fonticola) in the Comal River with the goals of generating a habitat occupancy equation, a population density equation, and developing a statistical methodology for handling similar situations. Field data collected on the Comal over a one year period contained. information on the physical, chemical, and vegetative environment as well as information on fish species composition and numbers. This data was systematically reduced, normalized, and then analyzed by various statistical techniques including principle component analysis, discriminate functions analysis, multiple regression analysis, and analyses of variance and covariance.