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Influence of Temperature on Habitat Use by East Pacific Green Turtles (chelonian Mynas) in an Urbanized Environment

出版	University of California, Davis, 2016
ISBN	13398249069781339824901
URL	http://books.google.com.hk/books?id=FZAztAEACAAJ&hl=&source=gbs_api

註釋Project Overview. Thermal characteristics of marine environments are changing rapidly on both global and local scales. Worldwide, ocean temperatures are increasing -- a trend expected to continue (Meehl et al. 2005; Bindoff et al. 2007; IPCC 2007). However, at the local level water temperature is more variable, demonstrating both warming and cooling through space and time (Hoegh-Guldberg and Bruno 2010; Kosaka and Xie 2013). Many marine organisms are adapted to specific, often highly constrained, thermal ranges. Global climate change and anthropogenic influences have already had dramatic effects on marine species (Harley et al. 2006; IPCC 2007; Hoegh-Guldberg and Bruno 2010). While large-scale changes in temperature can be attributed to shifts in the global climate regime, there are other human-mediated factors that influence local thermal conditions. One major anthropogenic influence on local marine environments is thermal effluent from power plants and industry that utilize once-through cooling (OTC) systems. The stations that use OTC systems generate waste heat, a by-product of the cooling process, which must be released into the environment (either via cooling towers or natural water source). Thus, OTC system stations alter the thermal environment proximate to their locations. Although local and global scale changes may be driven by different factors, changes to the thermal environment at the local level can provide a model system to study the effects of largescale climate change. Characterizing the responses of coastal fauna to rapid shifts in thermal conditions addresses a key gap in ecological knowledge -- understanding how populations of longlived marine vertebrates will be affected by a thermally dynamic environment that is changing at rapid rate. The fossil fuel-based South Bay Power Plant (SBPP) in San Diego, California was in operation from 1960 to 2010 and discharged warm-water effluent into southern San Diego Bay (SDB) and utilized an OTC system. East Pacific green sea turtles (Chelonia mydas), resident in SDB since at least the 1890's (Parsons 1962), have been routinely observed in the power plant outfall area since the 1960s (Stinson 1984; McDonald and Dutton 1990). Previous research suggests that these turtles used the outfall area to reduce metabolic costs and exhibit higher growth rates than other populations of green turtles (Eguchi et al. 2010, Eguchi et al. 2012). On December 31, 2009, two of the plant's four generators were permanently shut down; complete decommissioning of the plant occurred on December 31, 2010. This power plant closure provided a rare experimental opportunity to assess how rapid changes in the thermal environment will affect a resident marine turtle population in a coastal foraging area. The first chapter of my dissertation represents a review of the scientific studies that demonstrated physiological and behavioral changes across mobile aquatic reptiles utilizing these areas with heated effluent. I identify key responses to thermal effluent in reptiles in both marine and freshwater environments and present a case study from green turtles in SDB. The second chapter of my dissertation reflects my research using acoustic telemetry to monitor the changes in distribution and behavior of green turtles in response to the closure of the SBPP. The third and final chapter of my dissertation summarizes the changes of dive behavior by green turtles before and after the closure of the SBPP.