The ocean soundtracks available on YouTube are often calm and soothing but research shows that in reality, the actual sound of a healthy ocean is plagued with human-created noise.
The study published in the journal Science shows that human-induced noise or anthrophony has increased since the industrial revolution and it disrupts marine fauna's behaviour, physiology, reproduction and in extreme cases, causes even mortality. Since sound travels far and quickly underwater, the marine ecosystem and animals from invertebrates to whales that are sensitive to sound and use it as a prominent means of communication are negatively affected.
Soundscapes or the landscapes of the sound are a powerful indicator in revealing the health of the environment and a plagued ocean soundscape speaks volumes about its failing health.
The research team set out to document the impact of noise on marine animals and their ecosystems around the world. They assessed more than 10,000 papers to give compelling evidence and prove that human-made noise impacts marine life across multiple levels, from behaviour to physiology.
Global shipping alone is a huge contributor as it has cranked the low-frequency ocean noises by 32 times. Offshore drilling, sonar, seismic surveys, pile driving and even motorboats have chronic impacts on marine soundscapes.
"We all know that no one wants to live right next to a freeway because of the constant noise. For animals in the ocean, it's like having a mega-freeway in your backyard," said Ben Halpern, a co-author of the study and director of the National Center for Ecological Analysis and Synthesis at UC Santa Barbara.
Climate change also has detrimental impacts on ocean soundscapes. The deterioration of coral reefs which are known for playing a key role in species settling, reproducing and hunting has made the ocean far quieter. This could mean that the animals that depend on coral reefs' habitat noise to breed and forge will struggle to adapt to this drastic change.
Compared to other threats to the marine ecosystem like over-fishing, oil spills and waste dumping, the detrimental impacts of sound pollution have often taken a backseat in regulatory debates. Hence, no concrete policies have yet been taken up to redress the issue even after repeated warnings from biologists, ecologists and oceanographers.
The researchers pointed out that adopting concrete mitigation policy at a global level to tamp down the effect of anthrophony on marine life is the key to achieving healthier oceans. Changing ship machinery to reduce sound through simple technological innovations could help in the recovery of marine life.
A study conducted at the start of the COVID-19 pandemic near the Port of Vancouver found that a reduction in shipping traffic coincided with an average decrease of 1.5 decibels in waters along the shipping routes, thereby suggesting that the benefits of mitigation policies would be immediate.
The authors are hoping that the study will be an eye-opener in helping the world realize that tamping down the human-made noise in the ocean should be made the core component of environmental policy.