Review of noise impacts on marine mammals yields new policy recommendations — ScienceDaily
Marine mammals are particularly sensitive to noise pollution because they rely on sound to perform many basic functions, including communication, navigation, finding food, and avoiding predators. A team of experts has now published a comprehensive assessment of the existing science of how noise exposure affects the hearing of marine mammals, providing scientific advice on noise exposure standards that may have far-reaching implications for regulation.
Published on March 12, 2003 at Aquatic Mammals this paper is a major revision of the first such assessment published in the same journal in 2007. Both of these jobs were led by Brandon Southall, a researcher at the Institute of Marine Science at the University of California, Santa Cruz, and senior scientist at Southall Environmental Associates.
"One of the things we did in 2007 was to find out the main gaps in our knowledge. Now we have more data. We think there are enough new sciences to reconvene the expert group and revisit these issues, Said Southall. From 2004 to 2009, he served as Director of the NOAA Ocean Acoustics Program.
Concerns about the possibility of marine noise causing hearing loss or behavioral changes in marine mammals began to appear in the 1990s, with initial focus on activities related to the oil and gas industry. In the early 21st century, the large-scale mixing of sonar and deep dive whales became another focus. Transport and construction activities are other important sources of marine noise pollution.
Loud noise can cause temporary or permanent hearing loss, may mask other sounds, and may disrupt animals in a variety of ways. The new paper focuses on the direct impact of noise pollution on the hearing of marine mammals. A separate paper on behavioral effects and acoustics of different sound sources will be published later this year.
"The noise-induced hearing loss occurs in animals in the same way as humans. You can make short-term changes when you are exposed to loud noise, and you can make long-term changes, usually because of repeated insults." Author Colleen Reichmuth said he is a research scientist at the Pinniped Cognitive and Sensory Systems Laboratory at the University of California, Santa Cruz.
Because of the different sensitivities of animals to different types and frequencies of sound, the panel classified marine mammal species based on their knowledge of hearing. The new paper includes all marine mammal organisms.
"The diversity of species makes a one-size-fits-all approach impossible," said co-author Darlene Ketten, a neuroanatomist appointed by the Woods Hole Oceanographic Institute and Boston University's Hearing Research. central. “We need to understand how to avoid harm. The purpose is to provide guidance. If this or that species is in your area, this is what you need to avoid.”
The rapid increase in the number of marine mammalian hearing science research over the past decade has enabled the expert group to improve and improve its grouping and assessment. Attached to the document is a series of appendices that compile all relevant information on 129 marine mammals.
"We conducted a comprehensive species inspection of all living marine mammals," Reichmuth said, leading the work of these appendices. “We bring together the available knowledge covering all aspects of hearing, sound sensitivity, anatomy and sound generation. This is the scientific basis for the grouping of species used in noise exposure standards.”
"Appendix is a very important resource that does not exist anywhere else," Southall said. “The 2007 paper is the most influential single paper I have published – it is cited more in the literature than the sum of all my other papers – I hope this new paper will have a similar impact.”
The 2007 paper only covers species under the jurisdiction of the National Marine Fisheries Agency (NOAA Fisheries). The NOAA Fisheries in 2016 and 2018 were based on the US Navy's San Diego Naval Mammal Program, and the co-authors of the two papers, James Finneran's 2016 Navy Technical Report, issued US regulatory guidance.
In addition to covering all marine mammals for the first time, the new paper discusses the effects of air and underwater noise on amphibious species in coastal environments such as sea lions. Southall said that the release of new noise exposure standards and comprehensive synthesis of current knowledge in peer-reviewed journals is an important step forward.
"Regulators around the world are eager for this guidance," Southall said. "We still need more data, but we have made some significant progress."
The UCSC Pinniped Laboratory, now headed by Reichmuth, provides a wealth of new data on the hearing of amphibious marine mammals in the study of seals, sea lions and sea otters. Working at UCSC's Long Marine Laboratory with trained animals, Reichmuth's team was able to conduct controlled experiments and perform hearing tests similar to those used to study human hearing.
Finneran's project in San Diego and co-author Paul Nachtigall's project at the University of Hawaii provides a wealth of data for dolphins and other cetaceans.
However, some marine mammals, such as whales and other large whales, cannot be placed in a controlled environment where researchers conduct hearing tests. This is where Ketten's research institute uses biomedical imaging techniques, including CT and MRI, to study the auditory systems of various species.
"Simulation of animal hearing based on the anatomy of its auditory system is a very mature technique that can be applied to whales," Ketten explained. “We also model the species we can test in captivity, which allows us to hone the models and ensure they are accurate. There is a lot of resistance to modeling, but this is the only way to study hearing at some of the most likely In a species that is damaged by human voice."
Southall said that he often hears people around the world looking for guidance on adjusting noise through activities such as wind farm construction and earthquake surveys. “This paper has important international implications for regulating ocean noise,” he said.
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