Noise pollution is a growing issue on land -- but the seas are not safe either, apparently.
Marine shipping and construction, along with activity from sonar and seismic sensors are making the ocean a very loud place. While that may sound like just any other day in the big city, these high levels of noise pollution are causing a lot of damage to the health of marine ecosystems. A new paper reports on an "overwhelming body of evidence" that man-made noise is to blame.
Loud and deeply
"We've degraded habitats and depleted marine species," said Prof Carlos Duarte from King Abdullah University, Saudi Arabia, lead author of the study. "So we've silenced the soundtrack of the healthy ocean and replaced it with the sound that we create."
Sound plays a very important part in the lives of marine animals, the team explains, being involved in everything from feeding and navigation to communication and social interactions. A lot of what we know of marine animals such as whales comes from sound recordings.
But this state of affairs could change forever. According to the team, the youngest generations of marine animals are missing out on the "production, transmission, and reception" of key behaviors due to "an increasing cacophony in the marine environment" caused by man-made sound.
Freshly-spawned fish larvae use environmental sound and "follow it", Duarte explains. But these sounds that helped them navigate and understand their environment are now being drowned out. Beyond noise from vessels, sonars, and acoustic deterrent devices, energy and construction infrastructure are also contributing to the issue.
"[T]here is clear evidence that noise compromises hearing ability and induces physiological and behavioral changes in marine animals," the authors explain, adding however that currently "there is lower confidence that anthropogenic noise increases the mortality of marine animals and the settlement of their larvae" directly.
While the problems caused by marine sound pollution are pronounced and wide-reaching, the quarantine also showcased how quickly and easily they can be averted. According to the authors, levels of man-made sound in the ocean fell by around 20% last year.
Among some of the effects of this drop, the team notes that large marine mammals have been observed in waterways or coastlines that they've abandoned for generations. Such effects show that tackling the issue of marine noise is the "low-hanging fruit" of ocean health.
"If we look at climate change and plastic pollution, it's a long and painful path to recovery," Prof Duarte said. "But the moment we turn the volume down, the response of marine life is instantaneous and amazing."
The paper "The soundscape of the Anthropocene ocean" has been published in the journal Science.
