A Geomorphological, Ecosystem Services, and Population Dynamics Approach to Oyster Restoration and Management

摘要

Globally, estuaries support a diversity of habitat-producing ecosystem engineers and associated biotic assemblages that provide vital ecosystem services to coastal communities, such as support of viable fisheries, provision of nursery habitats, and water filtration. As a result of detrimental human activities within estuaries, many of these ecosystem engineers, and the associated habitat that they provide, have been degraded yielding concomitant reductions in the quantity and quality of provided ecosystem services. Estuarine habitat restoration has been the focus of many stakeholder groups to recover lost ecosystem services. In particular, the > 85% global loss of oyster reefs has prompted extensive, multi-scale restoration efforts. Despite considerable investment, the success of previous oyster restoration efforts is varied. To successfully restore oyster reefs to ensure sustainable enhancement of oyster population sizes and to maximize provision of ecosystem services, a comprehensive understanding of the factors that determine successful oyster restoration is required, including an understanding of the drivers of habitat quality, ecosystem service delivery, and metapopulation dynamics.;In Chapter 1, I identified an upper wave exposure limit above which natural intertidal oyster reefs cannot persist with implications for the siting and selection of materials for intertidal oyster reef restoration. In Chapter 2, I compared oyster density, demographic rates (growth and survival), and population estimates (1) across estuarine landscape settings (i.e., comparing natural intertidal reefs within adjacent water bodies that vary in tidal regimes and fetch distances) and (2) across natural habitats and human-made structures to assess variation in habitat quality between natural reefs and hardened shorelines to better inform future intertidal oyster reef restoration and shoreline management scenarios. In Chapter 3, I developed novel ecosystem service spatial layers for integration within a geospatial decision support tool that integrates multiple biophysical, socioeconomic and ecosystem service variables to identify optimal locations that maximize water filtration ecosystem service provision and long-term persistence of restored oyster populations. In Chapter 4, I adapted a size-structured, discrete-time matrix metapopulation model to simulate the dynamics of an oyster metapopulation to understand overall metapopulation trends, the degree and relative importance of local larval retention and inter-reef connectivity on metapopulation dynamics, and spatiotemporal variation in source-sink structure within the metapopulation with implications for oyster restoration and fishery management. Through informing the maximization of restored habitat quality, ecosystem service delivery, and metapopulation persistence and connectivity, the four chapters of this dissertation contribute support needed for a science-based approach to oyster restoration and management.