25 October 2021
Marine life drowned in manmade sound
Published online 9 February 2021
Noise pollution can be as damaging to marine life as its chemical counterpart, but also offers easier opportunities for remediation if policymakers move quickly.
Over the past century, humans have transformed the oceanic soundscape from a murmured conversation to a cacophony, with potentially serious consequences for all manner of marine life. A recent review in Science from an international team of researchers assesses how manmade noise affects the behaviour and health of oceanic species, and proposes countermeasures that might mitigate these effects.
“This source of pollution has been ignored over and over in global assessments of human pressures on the oceans,” says lead author, Carlos Duarte, of King Abdullah University of Science and Technology in Saudi Arabia. But the extent of the problem is profound. For example, over the past 50 years, shipping has contributed to a roughly 32-fold increase in low-frequency oceanic noise. Other sources, such as undersea construction and sonar systems, have further added to the din.
Unfortunately, this manmade—or ‘anthropogenic’—noise occurs at the same wavelengths that marine invertebrates, fish and mammals use to communicate, navigate and hunt. This loud and unnatural noise can thus mask the sound signatures these animals have evolved to rely upon for survival.
After reviewing the published literature, the authors found that 81% to 94% of the studies they examined demonstrated meaningful effects of anthropogenic noise on the behaviour or health of various categories of marine animals. These included negative impacts on predator evasion, habitat location, and foraging for organisms, ranging from shrimp to whales.
The good news is that there are immediate opportunities to turn down the volume. “Noise pollution represents by far the easiest global pressure to mitigate,” says Duarte, “in contrast to impacts such as chemical pollution, marine plastics, climate change and overfishing, where ocean recovery would require decades.” Appropriate measures could include quieter electric motors, propellers designed for reduced noise, adjustments to shipping routes and speeds—and regulations that promote the adoption of such measures.
Arthur Popper, who studies the effects of anthropogenic noise at the University of Maryland, agrees that this is a critical environmental issue. However, he notes that much of the research in this area—including work highlighted in this review—focuses excessively on ‘charismatic’ mammalian species while paying shorter shrift to more abundant and ecologically important species. “Compared to fishes and to invertebrates, marine mammals are a trivial component of aquatic life,” says Popper. Accordingly, he believes ideal marine noise management measures will require considerably more research to better understand how these diverse species hear and respond to shifts in the soundscape.
Duarte, C. M. et al. The soundscape of the Anthropocene ocean. Science 371, eaba4658 (2021).