Aquatic Sciences Meeting, Albuquerque 2001

SS45 Temporary Aquatic Ecosystems: Here Today, Gone Tomorrow (Spatial and Temporal Connections)

Date: Wednesday, February 14, 2001, Time: 3:00:00 PM

Location: Cochiti/Taos

Mueller-Solger, A, B, UC Davis / CA DWR, Davis, CA, USA, abmuellersolger@ucdavis.edu

Sommer, T, R, CA DWR, Sacramento, CA, USA, tsommer@water.ca.gov

Grosholz, E, D, UC Davis, Davis, CA, USA, tedgrosholz@ucdavis.edu

Schemel, L, E, USGS, Menlo Park, CA, USA, lschemel@usgs.gov

DAPHNIA RESPONSES TO VARYING FOOD RESOURCES IN TWO CONTRASTING CALIFORNIA FLOOD PLAINS

The Yolo Bypass is a large floodplain of the Sacramento River engineered to accommodate excess flows to prevent flooding of urban areas. The Cosumnes River flood plain is a much smaller, restored flood plain of the last unregulated river in central California. Both flood plains flood in winter and spring. They differ greatly in length of inundation, hydrology, and land use in and around the flood plain. This translates into differences in availability and quality of food resources for primary aquatic consumers. We explored differences in Daphnia magna growth and egg production rates when fed seston collected from the two flood plains and rivers. Daphnia responses showed considerable spatial and temporal variability. Food resource quantity and quality for Daphnia were better in the flood plains than in the rivers and at lower flows than at higher flows. Chlorophyll a concentrations were closely correlated with Daphnia growth and reproduction in both flood plains. In contrast, POC was closely related to Daphnia responses only in the Cosumnes flood plain, indicating better overall nutritional quality of POC in this more natural flood plain.

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Aquatic Sciences Meeting, Albuquerque 2001

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