Response of the San Francisco Bay to Natural and Anthropogenic Changes over the Last Decades

Friday, 19 December 2014
Melanie Raimonet1,2, James E Cloern1, Tara Schraga1, Alan D Jassby3, Anthony Malkassian4, Emily Novick4 and David B Senn4, (1)USGS, Menlo Park, CA, United States, (2)CNRS, Laboratoire des Sciences de l'Environnement Marin, Paris Cedex 16, France, (3)University of California, Department of Environmental Science and Policy, Davis, CA, United States, (4)San Francisco Estuary Institute, Richmond, CA, United States
Since 1968 the U.S. Geological Survey has maintained a program of research and observation in San Francisco Bay. We present a synthesis of this long-term data set to identify patterns of variability in water temperature, salinity, nutrients, suspended sediments and turbidity, dissolved oxygen, and phytoplankton biomass as chlorophyll a. The synthesis includes measures of water-quality changes over time, and uses simple models to identify potential drivers of those changes and answer a set of fundamental questions: (1) has San Francisco Bay warmed in response to recent decades of global warming; (2) do signals of oceanic variability, such as the past decade of low dissolved oxygen in coastal waters, propagate into the Bay; (3) has the Bay become more efficient at converting nutrients into phytoplankton biomass? Our purpose is to assess status and trends of water quality across the Bay, identify processes of variability and change over time, and to establish a 21st century baseline from which we can measure future responses to climate change and human actions.