Water Resources Research Act Program

Details for Project ID 2019CA026B

Towards a Mechanistic Understanding of the Multi-Scale Effects of Drought on Riverine Biodiversity

Institute: California
Year Established: 2019 Start Date: 2019-06-01 End Date: 2020-05-31
Total Federal Funds: $14,390 Total Non-Federal Funds: $21,795

Principal Investigators: Albert Vidal Ruhi

Abstract: Intermittent streams comprise more than half of the global river network, and have rich faunas that contribute importantly to regional biodiversity. However, these fluctuating ecosystems are often overlooked, and the mechanisms that allow organisms to persist in them are still poorly understood. This is particularly true for aquatic invertebrates, a diverse group of organisms that plays a central role in sustaining fishes and amphibians of conservation interest in California’s intermittent streams. Here we propose to study an intermittent river network in central California (Chalone Creek basin in Pinnacles National Park) to investigate how seasonal and supraseasonal droughts influence aquatic invertebrate composition and abundance. In particular, we will examine how drought severity (% flow intermittency) and habitat fragmentation (distance to the closest perennial reach) control three key processes that allow invertebrates to persist in the face of drought: storage effects (organisms and resistance eggs surviving in wet sediments), aerial dispersal (organisms re-colonizing actively through flight; or passively carried by the wind), and aquatic dispersal (organisms re-colonizing via swimming and drift). To this end, we will combine seasonal surveys across the basin (16 sites) with a novel dispersal experiment aimed at quantifying the relative importance of these three mechanisms. The proposed research will provide graduate student training opportunities, and will generate peer-reviewed publications, communications in conferences, a white paper for managers, and an open data product. Our results will allow anticipating the ecological effects of flow regime change (e.g., perennial to intermittent), as well as the existence of critical thresholds in hydrologic fragmentation across the landscape. Both are key aspects to fully understand, and be able to adapt to, California’s increasing hydroclimatic variability.