Sounds in the Seas

Researched by Danja

Global distribution of actively soniferous fish species found in a 2022 review. The relative size and colors of the circles represents a both the number of documented actively soniferous fish species, and b the percentage of documented actively soniferous species out of the total number of species and the percentage of documented actively soniferous species out of the number of species examined for sound production, respectively, native to each fishing area designated by the Food and Agricultural Organization of the United Nations as reported in rfishbase (Boettiger et al. 2012). Areas with no documented actively soniferous fish species are marked with an “X” symbol. Species may be listed in multiple fishing areas.Source: Looby, Audrey et al., 2022.

We often imagine the world beneath the waves to be a place of silence, a silence broken at most by the doleful song of a lonesome whale or by sounds from outside, muffled by the water. This misconception even reflects in common expressions like „mute as a fish“ or the title of Jacques Cousteau’s famous documentary „The Silent World“. In fact, sound propagates more easily in water than in air. And there is a wide variety of sound-producing beings in the seas – as well as a growing problem of human-caused noise pollution.

Sound Sources

The unique soundscape of a habitat is like a symphony, composed of a variety of sounds from diverse sources. Bernie Krause, a leading soundscape ecologist, bio-acoustician and sound artist first classified them into biophony, geophony and anthrophony.

Biophony

The sounds of all non-human living creatures (bios = life) contribute to biophony. In the oceans, these are typically marine mammals, fish, invertebrates or even passively produced sounds from algae.

• Marine mammals: Mammals like whales, dolphins and seals are the most commonly known sound producing animals in the seas.
• Soniferous fish: Some fish only produce sound passively, i. e. through feeding sounds etc., but many others also make active use of acoustic signals for communication purposes or as a sign of stress.
• Marine invertebrates: Shrimps, lobsters and even sea urchins produce sounds. While some of them are caused by their activities, others are produced actively for communication purposes.
• Algae: Not only animals contribute to the marine soundscape: In 2018, two oceanographers working with the US Naval Undersea Warfare Center in Rhode Island, Lauren and Simon Freeman, noticed a faint hiss in their recordings in the waters of Hawaii. They realized that the sound that had long been dismissed as caused by snapping shrimp correlated with the quantity of macroalgae covering the coral reefs. They set up a tank with controlled conditions and their presumption was confirmed: The sound is caused by the photosynthesis of the algae, releasing oxygen as a byproduct. When an oxygen bubble detaches from the surface, it creates a short ʻpingʼ sound. The combined pings of many algae merge to form a part of the background noise of their environment.

Geophony

Geophony is characterized by natural sounds caused by geological or meteorological processes like the sounds of rain, wind, melting ice, hydrothermal vents, and occasional earthquakes. The beautifully eerie song of colliding icebergs can be recorded from a distance of several thousand kilometers.

Anthrophony

Since the beginning of the industrial age, marine soundscapes have been increasingly characterised by humans. Some sounds are merely the by-product of human activities, such as the engine noise of ships, excavation activities like dredging or the noise of wind turbines. On the other hand, sounds are also used intentionally in various technologies: Seismic surveys use high-energy, low-frequency sounds in the search for resources below the seafloor while high-frequency sounds are used in echosounders and sonars to map the seabed or detect submarines and other targets.

Relevance

Marine animals make use of sound for a wide variety of communication purposes: From attracting potential partners to warning cries, sign of stress or defending their territories against intruders. The well-known songs of the whales even seem to mark distinct whale cultures within the same species. Since marine soundscapes are largely of biological origin, they carry a lot of information about a potential habitat and are therefore helpful for many species to find a suitable home, feeding or spawning ground.

The observation of marine sounds is also a valuable source of information for science: Monitoring the soundscapes of different habitats may open up new opportunities to evaluate and monitor ecosystems through acoustic recordings.

However, it is becoming increasingly difficult for marine life and scientists alike to navigate the sounds of the oceans: On the one hand, a 2016 study suggested that ocean acidification has negative effects on soundscape orientation in larval fish. On the other hand, human-caused noise pollution is extremely disruptive for many sea creatures. Studies found significant effects on behavior, presence, health, physiology, mortality, and demographic. While some attempt to drown out the noise (in what is known as the Lombard effect), others try to escape. Too often, this ends up creating mass strandings.

Art and Culture

• Sound artist, designer and researcher Leah Barclay works at the intersection of art, science and technology. Her works include immersive live performances, interactive installations and virtual reality experiences. She has been commissioned by organizations like the Smithsonian Museum, UNESCO, Ear to the Earth, Streaming Museum, Al Gore’s Climate Reality and the IUCN. http://leahbarclay.com/
• Bernie Krause’s scientific career started off in a musical career. He discovered his fascination with bioacoustics after incorporating natural sounds in his artistic work and went back to university to do a PhD in bioacoustics.
• OCEANS21, a project founded by Ina Krüger and Diana Schniedermeier, started off with the audiovisual installation “Seaphony - Life on Planet Ocean”. Recipients were invited to explore the soundscapes of various bodies of water around the world.

Further Listening

• Radio programme by Deutschlandfunk Kultur with a good introduction to the topic (German): https://www.deutschlandfunkkultur.de/der-neue-sound-der-ozeane-wie-menschen-den-klang-der-meere-veraendern-dlf-kultur-6ef0dd8f-100.html
• Sound library with an overview of biophonic, geophonic and anthrophonic sound sources: https://dosits.org/galleries/audio-gallery/
• Large database of fish sounds, which can also be searched by region: https://fishsounds.net/index.js
• Personal website of marine biologist Dr Rodney Rountree with many of his recordings: http://www.fishecology.org/soniferous/soniferous.htm
• Livestream of hydrophones off the North American coast; you might be lucky enough to hear whales and other sea creatures: https://live.orcasound.net/listen
• Sound library with different sound sources: https://ocr.org/sound-library/#
• Acoustic Data Portal: Overview of various projects on the subject of ocean sounds https://www.iqoe.org/acoustic-data-portal

Further Reading

• Looby, Audrey et al. "A quantitative inventory of global soniferous fish diversity", Reviews in Fish Biology and Fisheries, Vol 32, (2022).
• Duarte, Carlos et al. “The soundscape of the Anthropocene Ocean”, Science, vol. 371, (2021).
• Scheifele, P.M. et al., “Indication of a Lombard vocal response in the St. Lawrence River Beluga”, Acoustical Society of America Journal, Vol. 117, Issue 3, pp. 1486-1492, 2005.
• Tyack, Peter L. and Edward H. Miller, “Vocal Anatomy, Acoustic Communication and Echolocation”, Marine Mammal Biology: An Evolutionary Approach, (2002): 142-184.
• “Lost at sea: ocean acidification undermines larval fish orientation via altered hearing and marine soundscape modification”, Royal Society, (2016).
• Freeman, Simon E. et al., “Photosynthesis by marine algae produces sound, contributing to the daytime soundscape on coral reefs”, PLoS ONE, vol.13, issue. 10, 2018.
• Mercado, Eduardo III, “Song Morphing by Humpback Whales: Cultural or Epiphenomenal?”, Front. Psychol, vol. 11, issue, 574403, (2021).
• Hersh, Taylor A., “Dialects over Space and Time: Cultural Identity and Evolution in Sperm Whale Codas.
• Tyack, Peter L. and Edward H. Miller: Vocal Anatomy, Acoustic Communication and Echolocation, in: Marine Mammal Biology: An Evolutionary Approach, edited byb Rus Hoelzel, (2002):142-184.