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Cory T. Overton

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Fragmentation and loss of natural habitat have important consequences for wild populations and can negatively affect long-term viability and resilience to environmental change. Salt marsh obligate species, such as those that occupy the San Francisco Bay Estuary in western North America, occupy already impaired habitats as result of human development and modifications and are highly susceptible to increased habitat loss and fragmentation due to global climate change. We examined the genetic variation of the California Ridgway’s rail (Rallus obsoletus obsoletus), a state and federally endangered species that occurs within the fragmented salt marsh of the San Francisco Bay Estuary. We genotyped 107 rails across 11...
Categories: Publication; Types: Citation; Tags: Conservation Genetics
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Conservation efforts for greater sage-grouse (Centrocercus urophasianus), hereafter sage-grouse, are underway across the range of this species. Over 70 local working groups have been established and are implementing on-the-ground sage-grouse oriented conservation projects. Early on in this process, the California Department of Fish and Game (CDFG) recognized the need to join in these efforts and received funding from the U.S. Fish and Wildlife Service (USFWS) under the Candidate Species Conservation Program to help develop a species conservation plan for sage-grouse in the Mono County area. This conservation plan covers portions of Alpine, Mono, and Inyo counties in California and Douglas, Esmeralda, Lyon, and Mineral...
Categories: Publication; Types: Citation; Tags: Open-File Report
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Salt marsh faunas are constrained by specific habitat requirements for marsh elevation relative to sea level and tidal range. As sea level rises, changes in relative elevation of the marsh plain will have differing impacts on the availability of habitat for marsh obligate species. The Wetland Accretion Rate Model for Ecosystem Resilience (WARMER) is a 1-D model of elevation that incorporates both biological and physical processes of vertical marsh accretion. Here, we use WARMER to evaluate changes in marsh surface elevation and the impact of these elevation changes on marsh habitat for specific species of concern. Model results were compared to elevation-based habitat criteria developed for marsh vegetation, the...
Categories: Publication; Types: Citation; Tags: Estuaries and Coasts
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California Clapper Rails (Rallus longirostris obsoletus) are an endangered waterbird that forage in tidal-marsh habitats that pose risks from mercury exposure. We analyzed total mercury (Hg) in six macro-invertebrate and one fish species representing Clapper Rail diets from four tidal-marshes in San Francisco Bay, California. Mercury concentrations among individual taxa ranged from lowest at Colma Creek (mean range: 0.09–0.2 μg/g dw) to highest at Cogswell (0.2–0.7), Laumeister (0.2–0.9) and Arrowhead Marshes (0.3–1.9). These spatial patterns for Hg matched patterns reported previously in Clapper Rail blood from the same four marshes. Over 25% of eastern mudsnails (Ilyanassa obsolete) and staghorn sculpin (Leptocottus...
Categories: Publication; Types: Citation; Tags: Marine Pollution Bulletin
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