| SS9.01 Ecosystem Science Practiced in an Urbanized Estuary: South San Francisco Bay |
| Rollwagen Bollens, G, C, San Francisco State University, San Francisco, USA, rollboll@sfsu.edu |
| Bollens, S, M, San Francisco State University, San Francisco, USA, sbollens@sfsu.edu |
| Penry, D, L, University of California, Berkeley, Berkeley, USA, dpenry@socrates.berkeley.edu |
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| ZOOPLANKTON DYNAMICS IN THE LOWER SAN FRANCISCO ESTUARY: ROLE OF MICROZOOPLANKTON |
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| We sampled microzooplankton in South San Francisco Bay (SSFB) with two objectives: assess inter-annual/seasonal variability of microzooplankton abundance, and compare vertical distributions of microzooplankton and predators/prey vs. stratification. Ciliate biomass dominated in SSFB, and showed peaks during the spring bloom. Microzooplankton biomass was significantly higher in 1998 (El Nino) vs. 1999 (La Nina). During periods of high abundance, microzooplankton vertical distributions were more correlated with their copepod predators than their prey, and vice versa when in low abundance, and were never significantly correlated with stratification index. Previous results demonstrated copepods in SSFB preferred microzooplankton over diatoms during non-bloom periods and comprised at least 15-20% of copepod diet during the bloom. Tintinnid ciliates were also found to be a substantial component of larval herring diets. We conclude that, as with phytoplankton biomass, strong El Nino events lead to increased microzooplankton biomass, that biological factors play a larger role in determining microzooplankton vertical distributions than stratification, and that bloom periods of windows of opportunity for planktonic consumers and, by extension, higher trophic levels. |
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