Thesis

Population status of the endemic San Francisco damselfly (Ischnura gemina)

Ischnura gemina, the San Francisco forktail damselfly (Family Coenagriortidae) is endemic to the San Francisco Bay area, and is identified by the International Union for Conservation of Nature as a vulnerable species. Research from the late 1970s through the 1990s indicates a decline in the species’ populations. This study completes a comprehensive survey for I. gemina, and the closely related species I. denticollis, to determine the status of both species in areas previously surveyed. The study also seeks to determine the extent that various habitat variables, such as water chemistry and vegetation structure, predict the presence of I. gemina. Data from this study show a dramatic decline in populations of I. gemina since the 1980s and 1990s. In addition, results from this study indicate that I. gemina persists in sites with cooler temperatures and lower salinity than do other ischnuran or coenagrionid species. Finally, this study considers past research related to species conservation in light of climate change, and assesses the long-term viability of I. gemina under climate change. Of key interest is the tolerance for I. gemina under increasing temperatures and sea level rise. The goal for this research is to provide information on the current status of I. gemina and recommendations for its long-term conservation.

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