An anthropogenic cacophony
Sound travels faster and further in water than in air. Over the course of evolution, many marine organisms have become dependent on sound production, transmission and reception for important aspects of their lives. These important behaviors are threatened by increasing cacophony in the marine environment, as human-produced sounds are louder and more frequent. Duarte et al. discuss the importance of organically produced sounds and the ways anthropogenically produced sounds influence the marine soundscape.
Science, this issue p. eaba4658
Structured summary
BACKGROUND
Sound is the sensory signal that travels farthest across the ocean and is used by marine animals ranging from invertebrates to large whales to interpret and explore the marine environment and interact within and across species. Ocean sound landscapes are changing rapidly due to the dramatic decline in the abundance of sound producing animals, increases in anthropogenic noise and altered contributions from geophysical sources, such as sea ice and storms, due to climate change. As a result, the ocean’s soundscape in the Anthropocene is fundamentally different from that of pre-industrial times, where anthropogenic sound negatively impacts marine life.
PROGRESS
We find evidence that anthropogenic noise has a negative effect on marine animals. Strong evidence for such effects is available for marine mammals, and some studies find effects for fish and invertebrates, sea birds and reptiles as well. Ship noise, active sonar, synthetic sounds (artificial tones and white noise) and acoustic deterrents all affect marine life, as do energy and construction infrastructure noise and seismic surveying. While there is clear evidence that noise compromises hearing and induces physiological and behavioral changes in marine animals, there is less confidence that anthropogenic noise increases the mortality of marine animals and the establishment of their larvae.
OUTLOOK
Anthropogenic noise is a stressor for marine animals. Therefore, we call for it to be included in assessments of cumulative pressures on marine ecosystems. Compared to other stressors that are persistent in the environment, such as carbon dioxide released into the atmosphere or persistent organic pollutants released to marine ecosystems, anthropogenic noise is typically a point source pollutant, the effects of which diminish rapidly once the sources are removed. The evidence summarized here encourages national and international policies to become more ambitious in regulating and applying existing technological solutions to reduce sea noise and improve human stewardship of ocean sounds to maintain a healthy ocean. We offer a range of solutions that can help, supported by appropriate management and policy frameworks that can help reduce the impact on marine animals from anthropogenic noise and noise landscape disturbances.
The illustrations from top to bottom show ocean sounds from before the industrial revolution that consisted largely of sounds from geological (geophony) and biological (biophony) sources, with small contributions from human sources (anthrophony), to the current Anthropocene oceans, where anthropogenic noise and reduced biophony as a result of the depleted abundance of marine animals and healthy habitats have resulted in effects on marine animals. These effects range from behavioral and physiological to, in extreme cases, death. As human activities in the ocean continue to increase, management options must be deployed to prevent these impacts from growing under a “business-as-usual” scenario and instead leading to well-managed soundscapes in a future healthy ocean. AUV, autonomous underwater vehicle.
ILLUSTRATION: XAVIER PITA / FILE
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The illustrations from top to bottom show ocean sounds from before the industrial revolution that consisted largely of sounds from geological (geophony) and biological (biophony) sources, with small contributions from human sources (anthrophony), to the current Anthropocene oceans, where anthropogenic noise and reduced biophony as a result of the depleted abundance of marine animals and healthy habitats have resulted in effects on marine animals. These effects range from behavioral and physiological to, in extreme cases, death. As human activities in the ocean continue to increase, management options must be deployed to prevent these impacts from growing under a “business-as-usual” scenario and instead leading to well-managed soundscapes in a future healthy ocean. AUV, autonomous underwater vehicle.
ILLUSTRATION: XAVIER PITA / FILE
Abstract
Oceans have gotten significantly noisier since the Industrial Revolution. Shipping, resource exploration and infrastructure development have increased anthrophony (sounds generated by human activities), while biophony (sounds of biological origin) has been reduced by hunting, fishing and habitat degradation. Climate change has consequences for geophony (abiotic, natural sounds). Existing evidence shows that anthrophony affects marine animals on multiple levels, including their behavior, physiology and, in extreme cases, survival. This should encourage management measures to deploy existing solutions to reduce ocean noise levels, allowing marine animals to restore their use of ocean noise as a central ecological feature in a healthy ocean.