Food Web Structure in a Naturally Fragmenting Stream: Lagunitas Creek, Marin CA

This study aims to better understand the importance and function of dry-season fragmenting streams by examining the aquatic food web of the John West Fork of Lagunitas Creek CA. I am using stable isotopes of carbon and nitrogen to measure trophic changes in the aquatic food webs over the summer dry season. Eighteen individual pools were sampled on three occasions across the summer to collect representative organisms across the food web (algae, insects and fish).  Tissue samples were dried, pulverized and sent to the UC Davis Stable Isotope Laboratory for analysis.  Using the isotopic data of key species we will construct food webs from individual pools that dried at different times over the summer season. We are still waiting the results of the isotopic analysis, although its hypothesized that we will see ecological niche collapse for steelhead trout will occur during the low flow period.