Leatherback sea turtles (Dermochelys coriacea) react to impulsive sounds

Many marine ecosystems, including in the Northwest Atlantic, are expected to experience a sudden and sustained increase in underwater noise due to ocean development. To investigate the response of sea turtles to impulsive sounds, specifically those generated from seismic surveys, we equipped leatherback sea turtles at a seasonal foraging ground in coastal Massachusetts with data loggers to record video footage, sound, depth, and location. We then exposed the tagged turtles to a controlled short burst (0.25 ms), broad frequency (~ 300—1200 Hz), high intensity (sound source level of 221 dB re 1μPa) impulsive sound produced by a seismic sparker towed from a vessel. We collected a mean (± SD) of 109.4 ± 35.3 min of footage from 13 leatherbacks across four days in 2023, with the sparker exposure lasting 52.2 ± 11.6 min per turtle. Underwater peak sound pressure level of frequencies within the hearing range of leatherbacks (100—1200 Hz) were between ~ 128.5—176.2 dB during the tag deployments. We assessed the effects of peak sound pressure level on turtle behavior metrics and found that there was a significant effect on tortuosity, dive duration, and probability of foraging from the sound intensity coinciding with the emitted impulsive sound, while swim speed was more correlated with proximity to the sparker vessel regardless of sound intensity level. Probability of foraging declined by ~ 64% during the exposure period. These behavioral shifts along with their potential to decrease individual fitness, should be considered when evaluating the environmental impacts of intense acoustic stimuli on sea turtles.