Elizabeth Watson
University of California, Berkeley
507 McCone Hall
Berkeley, CA 94720
bethw@socrates.berkeley.edu
 Born in Sydney, Australia, and raised in Northern California, I have always lived within walking distance of the coast. This upbringing has left me in love with and in awe of coastal processes and given me an awareness of the dynamic nature of coastal systems.
After obtaining a B.A. in Integrative Biology from U.C. Berkeley, I worked at a NOAA research lab where I studied seasonal morphological change in coastal estuaries and the use of such estuaries by anadramous fish. I became attracted to the interdisciplinary nature of the geography department at Berkeley, where I earned an M.A. in 2002 studying tidal marsh formation and development with my current advisor, Professor Roger Byrne. My Ph.D. research will address environmental change in tidal marshes of San Francisco Estuary, from year-to-year variability to millennial scale change. A large component of this work involves an extensive re-survey of six San Francisco Estuary tidal marsh transects to detect changes in vegetation over the past 30 years.
In the future, I hope to continue field research in ecosystems of the Pacific Coast working either in academia or for public agencies. My seven year old daughter, Drisanna, is a frequent fieldwork companion, and reminds me of the importance of considering environmental processes on timescales longer than my own.
California tidal marsh vegetation change: a 30-year record of changes in plant distribution and abundance in tidal marshes of the San Francisco Estuary
Abstract
San Francisco Estuary tidal marshes are unique along the Pacific Coast of North America in extent, in plant species assemblages, and in the attention now being given to policy and restoration. Resurvey of vegetation transects in six San Francisco Estuary tidal marshes will provide a record of how tidal marsh plant community structure has evolved with thirty years of environmental change in freshwater flow and sea level rise in the San Francisco Estuary. Topography, plant distribution, pore water salinity, and soil organic matter will be assessed along historically surveyed transects in six intact tidal marsh ecosystems. We intend this study not only to provide a measure of how tidal marshes have responded to anthropogenic change, but also to inform policy decisions regarding marsh restoration, sea level rise, and water diversion from the Sacramento-San Joaquin Delta.
2005 Update
Funding provided by the Garden Club America for coastal wetlands research allowed me to complete a significant portion of the fieldwork for my dissertation, which focuses on past and current environmental change in San Francisco Estuary tidal marshes. During the summer and fall of 2004, I reoccupied and re-surveyed six vegetation transects originally surveyed during the mid-1970s, which span the full salinity gradient of San Francisco Estuary. The error associated with re-occupation was to within ±5 meters of the original transect. Plant cover was described, soil cores taken within the root zone of the marsh vegetation, and elevation was measured using a TopCon total station, referencing elevations to Coast and Geodetic Survey benchmarks. Soil cores were analyzed for porewater salinity, organic and total carbon content. These edaphic and elevational data were gathered in order to better interpret changes in plant cover as a function of changes in environmental conditions. Overall, we found significant changes in marsh vegetation at each marsh, co-incident with increases in sea level and increasing spring salinity due to an increasing water diversion. We found marsh vegetation in the fresh and brackish portion of the Estuary to be less consistent with what was found 30 years ago, while salt marsh vegetation displayed more fidelity. Additionally, we found more contractions among the distribution of dominant marsh plants in the fresh and brackish portions of the Estuary, and more expansions of dominant marsh plants at the more saline end of the estuary. We hypothesize that this is due to brackish marsh dominants having more narrow salinity tolerances: with increasing spring salinities, brackish marsh plants have been replaced by salt tolerant flora; at saline marshes, salt tolerant flora has expanded. This study adds a significant temporal dimension to studies of tidal marsh plant ecology, and elucidates how changing environmental conditions have impacted San Francisco Estuary tidal marshes.
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