| Summary: | Sea turtles spend the majority of their lives in the marine environment but are more easily accessible at their nesting beaches. Thus, understanding the relationships between their various foraging grounds and breeding areas is essential to assess population dynamics. In the particular case of the Northwest Atlantic (NWA) population, its life history stages and the habitats it occupies have been identified. What still remains poorly understood is the role loggerheads play within their ecosystems. Understanding the foraging ecology of loggerheads is necessary for revealing this role. The goal of this study was to further our understanding of the foraging ecology of loggerhead turtles in the North Atlantic Ocean using stable isotope analysis. First, I investigated the foraging habitats of highly elusive male loggerhead turtles using stable isotopes and satellite telemetry data. Male loggerhead isotopic data varied with foraging location and this is explained by geographic isotopic variation at the base of the food web. Also, comparison of male loggerhead isotopic values with those of female loggerheads revealed that males may exhibit similar foraging strategies (diet and habitat use) to those of females. Next, I characterized isotopically the foraging regions for loggerhead turtles in the NWA using a combination of satellite telemetry and stable isotope analysis, thus validating the use of stable isotope analysis to identify foraging areas of loggerhead turtles in the NWA. The largest assignment of nesting loggerheads to their foraging locations revealed that turtles segregate geographically in their use of foraging areas. I also examined the long-term consistency in resource use and degree of foraging specialization in male loggerheads. Individual male loggerheads exhibit a specialized foraging behavior similar to females that is consistent for up to 17 years. My results also revealed that resource diversity has an effect on the degree of individual specialization in loggerhead turtles. In summary, this study expanded our knowledge of loggerhead foraging strategies and demonstrated that carbon and nitrogen stable isotopes of loggerhead turtles are effective biochemical tags to link loggerhead foraging grounds and breeding areas.
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