Article

Estuaries

, Volume 26, Issue 4, pp 956-969

Selenium in San Francisco Bay zooplankton: Potential effects of hydrodynamics and food web interactions

  • David G. PurkersonAffiliated withRomberg Tiburon Center for Environmental Studies and Department of Biology, San Francisco State University
  • , Martina A. DoblinAffiliated withDepartment of Ocean, Earth, and Atmospheric Science, Old Dominion University
  • , Stephen M. BollensAffiliated withRomberg Tiburon Center for Environmental Studies and Department of Biology, San Francisco State UniversityMoss Landing Marine Laboratories, California State University Email author 
  • , Samuel N. LuomaAffiliated withWater Resources Division, United States Geological Survey
  • , Gregory A. CutterAffiliated withDepartment of Ocean, Earth, and Atmospheric Science, Old Dominion University

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Abstract

The potential toxicity of elevated selenium (Se) concentrations in aquatic ecosystems has stimulated efforts to measure Se concentrations in benthos, nekton, and waterfowl in San Francisco Bay (SF Bay). In September 1998, we initiated a 14 mo field study to determine the concentration of Se in SF Bay zooplankton, which play a major role in the Bay food web, but which have not previously been studied with respect to Se. Monthly vertical plankton tows were collected at several stations throughout SF Bay, and zooplankton were separated into two operationally defined size classes for Se analyses: 73–2,000 μm, and ≥2,000 μm. Selenium values ranged 1.02–6.07 μg Se g−1 dry weight. No spatial differences in zooplankton Se concentrations were found. However, there were inter- and intra-annual differences. Zooplankton Se concentrations were enriched in the North Bay in Fall 1999 when compared to other seasons and locations within and outside SF Bay. The abundance and biovolume of the zooplankton community varied spatially between stations, but not seasonally within each station. Smaller herbivorous-omnivorous zooplankton had higher Se concentrations than larger omnivorous-carnivorous zooplankton. Selenium concentrations in zooplankton were negatively correlated with the proportion of total copepod biovolume comprising the large carnivorous copepodTortanus dextrilobatus, but positively correlatid with the proportion of copepod biovolume comprising smaller copepods of the family Oithonidae, suggesting an important role of trophic level and size in regulating zooplankton Se concentrations.