Floods, Drought, and Alternate States in Algal-based River Food Webs

Year: 2020
Presenter/s: Mary E. Power
Symposium Session: 2020 - 00 Invited Speaker
Topics covered: adaptive management and monitoring, beavers, floodplain, hydraulics, sediment transport, and stream


In sunlit western rivers, winter and summer flows determine the production, types, and fate of algae in summertime food webs. Ecologically critical flows depend not only on precipitation regimes, but also on how precipitation is stored and released from a watershed’s “Critical Zone”: the weathered rock, soil, and vegetation that receives, transforms, and exchanges water between the atmosphere, subsurface storage, and runoff feeding surface waters. Different flow regimes lead to different alternative food web states, with different consequences for fish production and riverine linkages to upland and coastal ecosystems. The Eel River, a river along the California North Coast under Mediterranean seasonality, has shown us three alternative summer food web states, with food chains of different length that determine the production, food quality, and fate of attached algae and of the aquatic consumers that depend on them.