Cycles of boom and bust in coastal California intermittent streams

Authors: Michael* Bogan, Robert Leidy, Stephanie Carlson

Year: 2015 (xlvii)

Abstract

Intermittent streams in coastal California experience dramatic cycles of boom and bust across seasons and years. In wet winters these streams have many kilometers of flowing water, whereas in dry seasons or years only small, isolated pools remain. The communities inhabiting these remnant pools are rarely studied and their role in facilitating community recovery in adjacent reaches is unknown. We quantified community composition in remnant pools at one small and one large intermittent coastal stream in California: John West Fork (3 sq km) and Coyote Creek (240 sq km). After flow returned, we monitored community development in intermittent reaches adjacent to perennial pools. Both streams supported >150 invertebrate species in remnant pools. Coho salmon and steelhead inhabited pools at John West Fork, and 11 species of native fish and amphibians inhabited pools in Coyote Creek. Early in the wet season, communities in newly-flowing intermittent reaches were dominated by taxa with life stages resistant to drought (e.g. diapause). However, within several months taxa from perennial refuges had moved into adjacent intermittent reaches. Our results demonstrate the importance of perennial refuges in maintaining biodiversity in intermittent streams.