Friday, October 28, 2011
Hall 1-2 (San Jose Convention Center)
San Antonio Creek, located in Alameda County, CA, is characteristic of other Mediterranean climate streams in that the long-summer drought season results in the complete drying of some portions of the creek. This creek is situated upstream of a reservoir that serves as refugia for fish during the summer. To reach the reservoir, fish must migrate through the creek to the downstream reservoir. Fish that do not migrate downstream before the creek fragments become trapped in isolated pools, many of which dry completely before the end of the summer. The goal of this study is to compare the abundance and diversity of the fish community of isolated pools within San Antonio Creek. Another objective is to monitor changes in abiotic conditions, namely water volume and temperature of these selected pools across the drought season. To do so, we selected 20 pools at random to study across the drought season, which includes quantifying changes in habitat conditions as well as fish abundance and diversity. Fish were captured by electrofishing and seining. Captured fish were enumerated and identified to species. To quantify habitat available to the fish, the volume and average temperature of each pool were measured on a weekly basis. Preliminary results demonstrate that four species of freshwater fish are present including three native fishes (Catostomus occidentalis, Cottus asper, Oncorhynchus mykiss) and one non-native species (Micropterus salmoides). Results of this study will provide insight into the effects of drought disturbance and physical constraints on fish abundance and diversity in Mediterranean-climate streams.