CS39A Zooplankton - Feeding, Reproduction, Growth and Molecular Diversity
Date: Tuesday, June 11, 2002
Location: Poster Session - VCC
Mueller-SolgerAB, UC Davis, Davis, USA, amueller@water.ca.gov
Estuarine food resources for zooplankton according to C-N isotopes
Particulate organic matter in developed estuaries is derived from a large variety of aquatic and terrestrial sources and provides the food resource for primary consumers such as zooplankton. In the upper, freshwater portion of the San Francisco estuary, this large variety of source materials is reflected in highly variable seston carbon and nitrogen stable isotope signatures overlapping those of tested source materials. In contrast, C-N isotope signatures of major zooplankton groups (cyclopoid and calanoid copepods, and cladocera) and individual zooplankton taxa in 180 samples collected in various habitats of the upper San Francisco estuary over 13 months were much less variable. Zooplankton Delta C-13 values were most similar to those found for freshwater phytoplankton, while Delta N-15 values reflected the higher trophic position of copepods compared to cladocera. These results are consistent with recent findings about the nutritional importance of phytoplankton for primary consumers in detritus-rich estuarine environments.