There is a long-standing debate about how deep-sea mining can destroy the seabed and stir up fine sediment creating plumes of suspended particles, but there is another critical aspect that is often overlooked: underwater noise.
Wildlife NGO OceanCare has been campaigning against noise pollution for nearly two decades. “Underwater noise threatens marine life,” says Cyrill Martin, ocean policy expert at the marine wildlife protection NGO OceanCare. “High levels of noise would be emitted continuously for decades if deep-sea mining were allowed without additional research and regulations,” he adds.
Under the right conditions, low frequencies can be heard thousands of miles into the ocean. At about 800-1000 meters deep in temperate waters, the speed of sound is at its minimum, but it can travel long distances. This is called the Sound Fixing and Ranging (SOFAR) channel. For example, sounds generated in the southern Indian Ocean can be heard in both the North Atlantic and the North Pacific.
But how noisy is deep sea mining? While it is virtually impossible to assess the real impact of deep-sea mining, a comparison shows just how loud the noise emissions from deep-sea diving can be: it is estimated that all equipment used (sonars, multiple ships, dredges and drills) can emit a noise several times louder than a rocket launch.
No wonder all this noise is detrimental to aquatic life. Many marine species use sound to communicate with others, hunt, spot dangers, and find a mate. And it’s not just the whales and dolphins, who are known for their sophisticated songs. Many marine species depend on sound for their survival. Unfortunately, numerous studies have shown that noise can interfere with navigation and foraging, as well as cause health problems, such as hearing loss, internal injuries, impaired egg development, and deformities.
“About 150 marine species have been shown to be affected by noise, so there is no longer any doubt that underwater noise is a harmful and serious pollutant,” says Lindy Weilgart, marine biologist at Dalhousie University, Canada , and OceanCare consultant. “Humans are already making noise almost constantly through shipping, oil and gas exploration, military sonar and other activities. We see the consequences in whales, dolphins and other marine animals. Adding another source of constant, loud noise without further research on impacts and without significant efforts to reduce noise would be totally irresponsible.
The problem is, while we know that noise can affect marine life, this is still a relatively new area of research. As commercial deep-sea mining has yet to begin, researchers have not really studied its impact on a large scale. However, at the very least, the lack of information makes these projects even more dangerous.
“Many deep-sea species are not well understood, including how they might be affected by underwater noise or what ecological effects might result,” says deep-sea biologist Diva Amon. “Pursuing an experiment that could have long-term impacts on the deep sea or even the entire ocean (such as its ability to store huge amounts of carbon) is unwise. Out of sight doesn’t mean without impact. Humans tend to rush into activities without fully understanding their consequences, ”adds Cyrill Martin.
This is especially true because the benefits of deep-sea mining are not entirely clear. Some argue that the benefits outweigh the risks and that seabed minerals are essential to our technological future. However, there are alternatives and many battery manufacturers are already turning to more readily available materials, such as iron and phosphate.
Future actions
Suggestions recommended by OceanCare include:
- Restrict noise emissions until there is sufficient evidence to show that they do not significantly affect marine life
- Research all relevant aspects of noise pollution caused by deep sea mining
- Develop and adopt regulations and directives on environmental protection. For example, these regulations should define that underwater noise in mined areas and their surroundings should be at levels proven not to adversely affect the marine environment.
Interest in this topic is growing. Most recently, the European Parliament adopted resolutions incorporating a moratorium on deep-sea mining. In addition, industry representatives from Google, Philips, Volvo, Samsung and BMW also supported the temporary shutdown of deepwater mining operations and pledged to stop funding all deepwater mining activity. There is so much we don’t know about our waters and aquatic life, and it would be a shame to degrade it to such an extent that we would lose it before we could understand it.
