Phytoplankton photosynthesis drives many biogeochemical and ecological processes in lakes, estuaries, and the ocean. For example, dynamic changes in pH, trace metal speciation, and concentrations of dissolved gases (oxygen, carbon dioxide, methane), inorganic nutrients (nitrate, phosphate, silicate), and organic compounds (amino acids, organosulfur compounds) are all closely associated with fluctuations in phytoplankton photosynthesis. Trophic linkages also exist, between the phytoplankton as primary producers and populations of consumer organisms including bacteria, zooplankton, benthic invertebrates, and fish. Our scientific understanding of lakes and estuaries as dynamic ecosystems is therefore dependent upon a mechanistic understanding of both natural and human-induced variability of phytoplankton abundance, community composition, productivity, and connections to geochemical processes and other biological communities. These topics are central to poorly resolved issues such as: the growing worldwide incidence of toxic algal blooms and associated fish mortality, coastal eutrophication and increasing frequency/extent of hypoxia or anoxia, long-term and cyclic changes in fish stocks, the global significance of phytoplankton to the cycling of key elements such as carbon and nitrogen, and ecosystem- scale responses to both species extinctions and introductions of exotic species. This project's objectives are to: (1) study the distribution, abundance, species composition, and productivity of planktonic microalgae, animals, and bacteria in estuaries, (2) define and quantify processes that regulate population dynamics and productivity of planktonic organisms in estuaries, (3) define and quantify processes through which the plankton alter and reflect water quality in estuaries, (4) define and quantify benthic processes that affect plankton dynamics and productivity of estuaries, and, (5) define anthropogenic impacts on estuarine ecosystems. For additional information, see San Francisco Bay water quality page.
