Invasive Aquatic Animals and Possible Effects on Native Frogs and Toads in Mediterranean Baja California (1) (Research Notes‪)‬

Northwestern Baja California, Mexico, shares a unique mediterranean biota with adjacent California, USA, as a result of the climatic conditions that dominate the area. Many of the vertebrates in it are restricted to this ecosystem, including most amphibians (Linsdale 1932; Mellink 2002). This ecosystem faces severe conservation problems, mostly derived from the extensive urbanization of California and northernmost Baja California. The resulting habitat modification has impacted some of the species of amphibians in southern California so strongly that the arroyo toad (Bufo californicus; sensu Gergus 1998) is officially considered endangered, and the red-legged frog (Rana aurora), threatened. In contrast with their diminished populations in southern California, these species, as well as other frogs and toads, fare much better in Baja California (Grismer 2002). Besides knowledge of such better conditions, not much is known about the conservation status of amphibians in Baja California. There are a number of pressures that might impair the quality of their habitat, including development, land conversion, dams, sand-mining, gravel mining, roads, water extraction, refuse, chemical contamination, and invasive species (Robert E. Lovich, pers. comm.).