Projected shifts in loggerhead sea turtle habitat in the Northwest Atlantic Ocean due to climate change

32 It is well established that sea turtles are vulnerable to atmospheric and oceanographic 33 shifts associated with climate change. However, few studies have formally projected how their 34 seasonal marine habitat may shift in response to warming ocean temperatures. Here we used a 35 high-resolution global climate model and a large satellite tagging dataset to project changes in 36 the future distribution of suitable thermal habitat for loggerheads along the northeastern 37 continental shelf of the United States. Between 2009 and 2018, we deployed 196 satellite tags on 38 loggerheads within the Middle Atlantic Bight (MAB) of the Northwest Atlantic continental shelf 39 region, a seasonal foraging area. Tag location data combined with depth and remotely sensed sea 40 surface temperature (SST) were used to characterize the species’ current thermal range in the 41 MAB. The best-fitting model indicated that the habitat envelope for tagged loggerheads 42 consisted of SST ranging from 11.0° 29.7° C and depths between 0 – 105.0 m. The calculated 43 core habitat consisted of temperatures between 15.0° – 28.0° C and at depths between 8.0 – 92.0 44 m and the highest probability of presence occurred in regions with SST between 17.7° – 25.3° C 45 and at depths between 26.1 – 74.2 m. The habitat suitability model was then forced by a high46 resolution global climate model under a doubling of atmospheric CO2 to project loggerhead 47 probability of presence over the next 80 years. Our results suggest that loggerhead thermal 48 habitat and seasonal duration will likely increase in northern regions of the NW Atlantic shelf. 49 This change in spatiotemporal range for sea turtles in a region of high anthropogenic use may 50 prompt adjustments to the localized protected species conservation measures. 5