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Open Access Publications from the University of California

Scholarly Works (2 results)

  • Article
Capstone Projects (2010)
Over the past century, sea level has risen more than 20cm along the California coast, and it is projected that under medium-high emissions, mean sea level will rise by 1.4m over the coming century. The likelihood of losing current beach habitat due to sea-level rise constitutes a major threat for many wildlife species, such as pinnipeds that require terrestrial habitat for breeding, pupping, molting, and resting. This study applies GIS to analyze the impacts of sea-level rise on pinniped haul-out sites along the central and southern California coast. ArcMap was used to overlay inundation data with haul-out sites of three abundant California pinniped species: California sea lions (Zalophus californianus californianus), Pacific harbor seals (Phoca vitulina richardsi), and Northern elephant seals (Mirounga angustirostris). Affected area due to sea-level rise was also quantified for Northern elephant seal haul-out sites. GIS data showed that approximately 99% of haul-out sites among all species were affected throughout central and southern California. Furthermore, over 373,000m2 of elephant seal habitat was found to be affected by sea level rise. These impacts may result in loss of pinniped habitat, redistrubtion of haul-out sites, and controversy over land use for humans or for pinnipeds. Given the potential for conflict, policymakers should begin to assess the Marine Mammal Protection Act and Coastal Act to ensure that these legislations will be able to meet management needs. Furthermore, adaption strategies such as structural protection may help alleviate pressure on pinniped habitat and prevent future controversy over land allocation.
    Cover page: The Impact of Sea-Level Rise on Pinniped Haul-Out Sites Along the California Coast
    • Thesis
    • Peer Reviewed
    UC San Diego Electronic Theses and Dissertations (2023)

    Predicting ecological responses to changing ocean conditions is particularly challenging in highly dynamic marine ecosystems subject to multiple anthropogenic stressors. My dissertation centers upon understanding fine- and broad-scale patterns that affect energy flow through the California Current Ecosystem (CCE), a dynamic coastal upwelling zone in the eastern Pacific Ocean. I focus on trophic relationships between top predators and their prey by using an iconic indicator species – the California sea lion (Zalophus californianus; sea lions) – and a complex of key forage species to elucidate food web dynamics in the ecosystem.

    In Chapter 1, I explore fine-scale temporal, spatial, and physiological patterns that drive the quality of prey species to top predators in the CCE and use bomb calorimetry to generate a novel dataset of energetics information on these forage species. I then integrate my findings with published data on the bioenergetics of sea lions to quantify how predator consumption rates can vary, given the differences in quality I observed within and among prey species. In Chapter 2, I argue that sea lions are an important ecosystem indicator of major food web shifts, which I determined by generating a ~55-year time series of sea lion trophic position using stable isotope analysis of archived tissues coupled with several environmental datasets. My findings demonstrate that regime shifts of two of the most important forage fishes to predators in the CCE can be observed through the trophic lens of sea lions. Sampling of archived tissues to create environmental chronologies is a process laden with error. Therefore, in Chapter 3, I constructed a Bayesian model to quantify the uncertainty in building ecological datasets from growth increment sampling of archived tissues (e.g., teeth, bones). This method can be applied to studies using these structures to create time series of importance for conservation and management questions.

    My research fills critical knowledge gaps in our understanding of marine food web dynamics on multiple timescales that will contribute to the literature on community structure and function, while also providing important baseline data that will be useful in assessing future ecosystem states in a time of unprecedented change.

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