Climate Change The Not-So-Silent Depths – Eos – GWC Mag gwcmagFebruary 10, 2024031 views Editors’ Vox is a blog from AGU’s Publications Department. The oceans are a surprisingly noisy place with acoustic signals caused by many different things. For some time, scientists have been studying earthquakes and tremors recorded on the seabed but disregarded other signals that the equipment detected as background noise. A new book published in AGU’s Geophysical Monograph Series, Noisy Oceans: Monitoring Seismic and Acoustic Signals in the Marine Environment focuses on non-tectonic marine noise, presenting a comprehensive review of acoustic signals from environmental, biological, and anthropogenic sources. We asked the book’s editors to tell us about different types of marine noise and explain what their book explores. What kind of noises can be heard in the oceans and how can they be categorized? The oceans are surprisingly noisy places, hence our choice of title for the book. Noises from animals, such as fish and whales, can be heard in the oceans, as well as noises originating from the Earth, for example submarine volcanoes and marine landslides. In many places there are also noises from humans coming from ships and from drilling and mining activities. Thus, ocean noise can be categorized into biological, geological, and human made noises. A mother sperm whale and her calf off the coast of Mauritius. Whales make a range of noises including clicks, whistles, and pulsed calls for different purposes including navigation, finding one another, and socialization. Credit: Gabriel Barathieu, CC BY-SA 2.0 DEED Why were non-seismic sounds and signals disregarded in the past? Past technology did not allow us to record the ocean soundscape. Also, identifying the origin of noises can be difficult if no visual observations are made at the same time as the recordings. Thus, until recently, it was widely believed that the oceans were silent places. In comparison, the terrestrial soundscape has been studied for a much longer time due to easy access for instrumentation deployment and observations and because of its direct impact on daily life. What technological advancements have made studying these “other” noises possible? The Kavachi submarine volcano erupting in the Western Province of the Solomon Islands. When a volcano erupts underwater, the release of volcanic material and its interaction with water makes a noise. Also, if an earthquake coincides with an eruption, its seismic energy is converted into acoustic energy and thus can be heard. Credit: Alex DeCiccio, CC BY-SA 4.0 DEED Today, we can record the ocean soundscape and identify the origin of different noises using hydrophones and ocean-bottom seismometers in semi-real time and permanent seafloor observatories in real time. Processing techniques and computational power have shortened processing times and advanced the detection of repetitive signals in large data quantities. These advances have led to better knowledge of the marine soundscape and made us aware of the risks of increasing noise in the oceans. It has also opened the door for new techniques to monitor natural risks, for example from volcanoes and landslides. How is your book organized to explore different types of marine noise? Our book attempts to compile a comprehensive set of commonly observed non-tectonic marine noise. It includes reviews on different signals and examples of research where these signals have been studied. After an introductory chapter about the marine soundscape, there are 13 chapters presenting different signals, for example from volcanoes, whales, and marine traffic. Our concluding chapter puts the book into a broader context, including the “Decade of Ocean Science for Sustainable Development (2021-2030)” and proposes future actions such as the creation of submarine noise maps. What kind of case studies are presented in your book? This book contains different case studies from geological, biological, and anthropogenic noise. One example presents tracking of whales from the recording of their vocalizations. Similar experiments on a wider scale could give much needed details of whale migration and behavior. Another case study discusses the noise that gas bubbles generate when leaving the seafloor. Recording the amount of gas bubbles can give information about gas exchange through the seafloor, including possible greenhouse gases, and thus offers insights into the role of the oceans in regulating our climate. Who will find this book useful? We hope this book will be interesting to students, teachers, and researchers studying the marine environment, including geologists, geophysicists, volcanologists, and biologists. It will hopefully also be of use to decision makers and policy makers developing regulations and laws concerning the impact of sound on marine life. Noisy Oceans: Monitoring Seismic and Acoustic Signals in the Marine Environment, 2023. ISBN: 978-1-119-75089-5. List price: $200 (hardcover), $160 ebook. Chapter 1 is freely available. Visit the book’s page on Wiley.com and click on “Read an Excerpt” below the cover image. —Gaye Bayrakci (G.Bayrakci@noc.ac.uk; 0000-0003-1851-5021), National Oceanography Centre, UK; and Frauke Klingelhoefer (fklingel@ifremer.fr; 0000-0001-5838-0577), IFREMER (French National Institute for Ocean Science), France Editor’s Note: It is the policy of AGU Publications to invite the authors or editors of newly published books to write a summary for Eos Editors’ Vox. Citation: Bayrakci, G., and F. Klingelhoefer (2024), The not-so-silent depths, Eos, 105, https://doi.org/10.1029/2024EO245005. Published on 9 February 2024. This article does not represent the opinion of AGU, Eos, or any of its affiliates. It is solely the opinion of the author(s). Text © 2024. The authors. CC BY-NC-ND 3.0Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited. Related