The response of ecosystems to climate change is difficult to evaluate and predict, and often are constrained by anthropogenic modifications to the natural environment. Here, I assess the impacts of sea-level rise and extreme storm events on a tidal salt marsh ecosystem located in San Francisco Bay estuary (California, USA) that contains local endemic and endangered wildlife species. The San Francisco Bay estuary has been heavily impacted from human development resulting in the loss of over 80% of its historic tidal salt marshes. In this dissertation, I hypothesize that there will be short-term impacts from extreme storm events and long-term impacts from sea-level rise on the San Pablo Bay endemic marsh wildlife. The first chapter of this dissertation is a discussion about the current state of understanding about climate change impacts on salt marsh habitats and wildlife, using San Pablo Bay National Wildlife Refuge (SPBNWR) as a case study. The second chapter documents two extreme storm events in 2010 and 2011, and discusses impacts on available marsh habitats. At peak storm surge, over 65% (2010) and 93% (2011) of the marsh habitat for wildlife was under water, presumably increasing predation and drowning risk. In the third chapter, I evaluate if SPBNWR is currently keeping pace with sea-level rise and what biogeomorphic processes may be important. Subsidence and accretion was found to vary spatially, with only 37% of the marsh keeping pace with current sea-level rise rates. Surprisingly, I found widespread subsidence (55%) in areas adjacent to constructed levees. Using Akaike Information Criterion (AICc), I found that the distance from the sediment source (San Pablo Bay edge) was the most important covariate to determine accretion. In the fourth chapter, I develop a spatially-explicit, sea-level rise response model for SPBNWR to assess habitat resiliency to 2100. The model projected a loss of most high marsh habitat by 2050, and a loss of most mid marsh habitat by 2040 to 2060. Low marsh habitat showed a temporary increase in area between 2030 and 2050, with the peak (658 ha) in 2040. A large eastern portion of the marsh or 75% of the area (1,004 ha) converted to predominantly mudflat by 2060 with a 47 cm increase in sea-level. However, an almost complete conversion to mudflat occurred with a 75 cm sea-level rise by 2080, with <10% of the area still in marsh vegetation. The findings from this dissertation provide insight into sea-level rise and storms impacts on marsh habitats, which have been set aside for the protection of endangered species.
|Advisor:||Elliott-Fisk, Deborah L.|
|Commitee:||Takekawa, John Y., Ustin, Susan L.|
|School:||University of California, Davis|
|School Location:||United States -- California|
|Source:||DAI-A 74/02(E), Dissertation Abstracts International|
|Subjects:||Ecology, Geography, Climate Change|
|Keywords:||Accretion, Endangered, Salt marshes, San Francisco Bay, Sea-level rise, Storm, Wildlife|
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