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Abstract Incidental capture of non-target species poses a pervasive threat to many marine species, with sometimes devastating consequences for both fisheries and conservation efforts. Because of the well-known importance of vocalizations in cetaceans, acoustic deterrents have been extensively used for these species. In contrast, acoustic communication for sea turtles has been considered negligible, and this question has been largely unexplored. Addressing this challenge therefore requires a comprehensive understanding of sea turtles’ responses to sensory signals. In this study, we scrutinized the avenue of auditory cues, specifically the natural sounds produced by green turtles (Chelonia mydas) in Martinique, as a potential tool to reduce bycatch. We recorded 10 sounds produced by green turtles and identified those that appear to correspond to alerts, flight or social contact between individuals. Subsequently, these turtle sounds—as well synthetic and natural (earthquake) sounds—were presented to turtles in known foraging areas to assess the behavioral response of green turtles to these sounds. Our data highlighted that the playback of sounds produced by sea turtles was associated with alert or increased the vigilance of individuals. This therefore suggests novel opportunities for using sea turtle sounds to deter them from fishing gear or other potentially harmful areas, and highlights the potential of our research to improve sea turtles populations’ conservation.

Marine herbivores face rapid changes in the coastal ecosystems where they forage. In the Caribbean, the recent and fast expansion of the invasive phanerogam species Halophila stipulacea is threatening native seagrass ecosystems. So far, H. stipulacea is escaping most Caribbean herbivores, certainly because of its recent introduction or lower nutritional value. We investigated the impact of H. stipulacea invasion on fine-scale foraging habitat selection and food resource selection of immature green turtles at critical foraging sites in Les Anses d′Arlet, Martinique. The analysis of seagrass distribution and nutritional content, together with turtle behaviour and resource selection, showed that H. stipulacea may be of contrasting interest to green turtles. Compositional analysis confirmed the lower nutritional value of H. stipulacea compared to the native species, but the invasive species showed higher digestibility than native ones, which calls into question the energetic advantage of consuming the native plants over the exotic plant. Thus, although green turtles mostly selected the native seagrass Thalassia testudinum in multispecies seagrass beds, some individuals fed on H. stipulacea. Accordingly, in bays entirely invaded by H. stipulacea, one possibility for resident green turtles is to increase foraging on this species, but, if so, the consequences on their growth and survival still remain to be determined. As the expansion of H. stipulacea may have been facilitated by factors such as shipping, anchor scarring and fishing activities, protection of native seagrass beds and immature green turtles from human disturbances is urgently required to ensure the long-term adaptation of green turtles to this new foraging environment.