Sea level rise, land use, and climate change influence the distribution of loggerhead turtle nests at the largest USA rookery (Melbourne Beach, Florida)

Anthropogenic climate change adds to the existing suite of threats to species, such as habitat degradation, by increasing extinction risk and compromising the ability of species to respond adaptively to these stressors. Because threats from anthropogenic climate change often interact synergistically with other threats, integrated assessments of the factors and processes that affect species persistence and distribution are required. We assessed the influence of coastal land use and climate change (specifically sea level rise) on the spatial distribution of nests within the largest loggerhead Caretta caretta marine turtle rookery in the Atlantic Ocean, at Melbourne Beach, Florida, from 1986 to 2006. We generated a multiple regression model based on climate change, sea-level rise and land use that describes 47% of the spatial variation in loggerhead nest- ing. Nests have shifted northward (likely in response to warming temperatures), away from inten- sive coastal development, and, surprisingly, toward areas of increased erosion. Using the Bruun Rule (an approximation of the response of the shoreline profile to sea level rise), we modeled the impacts of sea level rise of 0.25 and 0.5 m in conjunction with extrapolations of coastal develop- ment and a continued northward shift in nest distribution. We project up to a 43% decrease in beach area from 1986 to a future with 0.5 m of sea level rise and predict that loggerhead nesting will shift northward and become increasingly crowded on narrowing beaches. An implication of this study is that areas currently protected for large rookeries may not overlap with their future distributions.