Endangered Sea Turtles’ Sensitivity to Low-Frequency Noise Raises Conservation Concerns
Kemp’s ridley sea turtles, one of the most endangered sea turtle species globally, are highly sensitive to low-frequency sounds – the same frequencies produced by ship traffic and industrial activity. New research, published today, , reveals the extent of this sensitivity and highlights potential implications for conservation efforts. The findings underscore the challenges these turtles face as they navigate increasingly noisy ocean environments.
These turtles inhabit the eastern and Gulf coasts of North America, areas coinciding with some of the world’s busiest shipping routes. While threats like accidental capture in fishing gear, pollution, and vessel collisions are well-documented, the impact of underwater noise pollution has remained less clear – until now. Researchers from Duke University Marine Laboratory, the National Oceanic and Atmospheric Administration (NOAA), and North Carolina State University collaborated on the study, aiming to understand how Kemp’s ridley turtles perceive sound.
Understanding the Turtles’ Auditory Capabilities
The research team employed a non-invasive technique to assess the turtles’ hearing range. Sensors were attached to the turtles’ heads to record electrical activity along their auditory nerves as they were exposed to a range of frequencies. The tests covered sounds from 50 hertz (Hz) – near the lower limit of human hearing – up to 1,600 Hz. The results demonstrated that the turtles exhibited the greatest sensitivity to sounds around 300 Hz, with their ability to detect higher frequencies diminishing.
“Our findings indicate that the turtles are most sensitive in the same low-frequency band where much industrial and vessel noise occurs,” explained Charles Muirhead, an author of the study. This doesn’t automatically equate to harmful effects, he clarified, but it does pinpoint areas where further monitoring and targeted impact studies are crucial.
Why Low-Frequency Noise is a Concern
Sound travels efficiently underwater, particularly at lower frequencies. This means that noise generated by ships, dredging operations, and oil exploration platforms can propagate over considerable distances. For marine animals like Kemp’s ridley turtles, sound is a vital sensory tool used for navigation, foraging, and communication. The overlap between human-generated noise and the frequencies turtles rely on raises concerns about potential disruptions to these essential behaviors.
The turtles’ habitat – nearshore and shelf waters – exacerbates the problem. These areas are characterized by intense human activity, meaning the turtles are frequently exposed to multiple stressors throughout their life cycle. As Muirhead noted, they face threats from fishing gear, plastic ingestion, and habitat degradation, in addition to the potential impacts of noise pollution.
The Next Steps in Sea Turtle Noise Research
The current research represents an important first step in understanding the auditory sensitivity of Kemp’s ridley turtles. The team is now planning to investigate how these turtles respond to sound in real-world ocean conditions. This will involve observing their behavior in the presence of varying noise levels and attempting to correlate the laboratory findings with physical effects observed in their natural habitat.
“These efforts will help refine our understanding of how human-caused noise interacts with sea turtle sensory systems,” Muirhead stated. “They will also support evidence-based management approaches aimed at minimizing unintended impacts while balancing human activities in coastal and offshore waters.”
The researchers hope that a more comprehensive understanding of the turtles’ hearing capabilities will inform conservation strategies and lead to measures that mitigate the impact of noise pollution on this critically endangered species. The study, published in JASA on behalf of the Acoustical Society of America by AIP Publishing, provides a crucial foundation for future research and conservation efforts.
While the precise effects of noise pollution on Kemp’s ridley turtles remain to be fully elucidated, the research underscores the importance of considering the acoustic environment when managing and protecting marine ecosystems. The findings serve as a reminder that even seemingly distant human activities can have far-reaching consequences for vulnerable wildlife.
