PARENT SESSION
Oral Session # 44: Resource Management I: Theory; Aquatic Systems.
Presiding: C Swan
Wednesday, August 6. 8:00 AM to 11:30 AM, SITCC Meeting Room 106.

Factors limiting spread of the crayfish, Procambarus clarkii, in Santa Monica Mountain streams.

Kerby, Jacob^{*,1, 2}, ¹ University of California, Davis, CA² California State University, Northridge, CA

ABSTRACT- Invasive species are a major threat to stream ecosystems; however, research has seldom identified successful ways of prohibiting their spread. We surveyed 32 stream sections in the Santa Monica Mountains of southern California for two consecutive years to determine the distribution of the invasive crayfish, Procambarus clarkii. Surveys indicated that streams with large obstructions (waterfalls, culverts, artificial structures) often did not have crayfish present upstream of these obstructions. A mark recapture study indicated that P. clarkii displayed significantly more downstream than upstream movement when observed in three successive stream pools. Obstructions significantly reduced movement of crayfish between pools when compared to stream sections without any obstructions. The distribution of crayfish in streams and mark-recapture data thus suggest that crayfish mainly spread downstream from a point of colonization and are restricted in their movement to adjacent upstream sections by the presence of both natural and artificial obstructions.

Key words: Crayfish, Procambarus clarkii, Invasive, Amphibian