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ESR prepress abstract   -  DOI: https://doi.org/10.3354/esr01027

Effects of a power plant closure on home ranges of green turtles in an urban foraging area

Tomoharu Eguchi*, Jessica Bredvik, Suzanne Graham, Robin LeRoux, Brendan Saunders, Jeffrey A. Seminoff

*Corresponding author:

ABSTRACT: A natural experiment was conducted to determine effects of a fossil-fueled power plant on home ranges of east Pacific green turtles Chelonia mydas in an urban foraging ground. The power plant, located in south San Diego Bay, California, USA, co-existed with a resident foraging aggregation of approximately 60 green turtles for ~50 years. It was decommissioned during a long-term green turtle monitoring study, thus providing a rare opportunity to evaluate how the cessation of warm-water effluent affected turtle movements and habitat use in the area. Seven and 23 green turtles were equipped with GPS-enabled satellite transmitters during pre- and post-decommissioning of the power plant, respectively. Useful data were obtained from 17 turtles (4 for pre- and 13 for post-decommissioning). Core use areas (50% utilization distribution: UD) increased from 0.71 to 1.37 km2 after the power plant decommissioning. Increase in 50% post-power plant UD was greater during nighttime (0.52 to 1.44 km2) than daytime (1.32 to 1.43 km2). Furthermore, UDs moved from the effluent channel to an area closer to seagrass pastures, a presumed foraging habitat of the turtles. The observed expansion of green turtle home ranges may increase turtle–human interactions, such as boat strikes, within the foraging ground; this underscores how seemingly innocuous human actions contribute to inadvertent consequences to wildlife. Possible management and conservation actions include increasing awareness of the public regarding turtle presence in the area through signage and education, as well as legislating for a reduction in boat speeds in select areas of the bay.