[MEXICO CITY, SciDev.Net] Noise pollution from deep-sea mining carries an invisible risk for sea-life, warn researchers, urging greater transparency from the industry to help mitigate the harms.

Noise in the deep ocean can lead to a cascade of ecological consequences, altering biodiversity and the behaviours and physiology of many species, research has shown.

This could impact a food chain and ecosystem relied upon by Latin American coastal communities, according to marine experts.

An analysis of more than 2,800 investigations conducted in the Clarion-Clipperton zone (CCZ) — a vast underwater plain twice the size of India located in the Pacific Ocean between Hawaii and Mexico — revealed that most of the types of animals that inhabit it are sensitive to sound.

Much of marine life, including invertebrates, fish, and mammals, rely on sound for communication, navigation, and predator avoidance.

However, the effects of noise pollution have only been studied in 35 per cent of species, according to the article to be published in the September issue of Marine Pollution Bulletin. Researchers say more data sharing is needed to understand the true impacts.

Travis Washburn, an assistant professor at Texas A&M University, in the US, and one of the authors of the paper, told SciDev.Net: “We knew there wouldn’t be data on the deep sea, but I was surprised [at how little] data there was on even the shallow stuff.”

“It’s just a big question mark a lot of time,” he said.

It comes as 37 countries launched the first ever global political coalition to reduce harmful underwater noise pollution at the UN Ocean Conference in Nice, southern France, this week.

The High Ambition Coalition for a Quiet Ocean commits to support policies that promote quieter ship design, establish marine protected areas, and support capacity-building to assess and reduce ocean noise.

Speaking at the conference, UN Secretary-General António Guterres warned that unregulated deep-sea mining could turn the ocean into a lawless “Wild West”.

The CCZ, dotted with shiny black rocks, is the world’s largest mineral exploration region, full of mineral-rich deposits of cobalt, nickel, manganese and rare earths.

For industry, exploiting these deposits is the key to the energy transition. For governments, it is the epicentre of a global dispute.

Meanwhile, for many in the scientific community it is an issue that, considering mounting evidence, demands a precautionary approach.

According to the study, up to one third of fish species in the CCZ may be soniferous, meaning they produce or carry sound. Noise pollution can lead to changes in the physiology and behaviour of such species.

“They use it for everything: communication, finding mates, avoiding predators, finding food,” explained study co-author Lucille Chapuis, an expert in marine bioacoustics at La Trobe University in Melbourne, Australia.

“If we add noise into the system, then these functions are just masked or disrupted.”

Around three quarters of the publications reviewed in the study focused on mammalian and fish species, underscoring a major knowledge gap.

“Invertebrates are massively underrepresented, and the problem is that a lot of the CCZ biodiversity is actually invertebrates,” said Chapuis.

“We know very little about what the responses of these animals are to sound, or whether they can perceive sound.”

A lack of transparency from mining companies also means that data on noise is lacking.

“There’s literally no published data out there on what the sound levels on actual mining activities are going to be — it’s all proprietary,” added Washburn.

“So, we actually used a lot of coastal proxies to get a rough estimate.”

For Daniel Cáceres, a Peruvian specialist in ocean governance who did not participate in the research, the study shows that the impact of mining in the CCZ is neither distant nor abstract.

“The sound waves could affect migratory species, regional food chains and ecosystems that have ecological connections with the coasts of Latin America,” he said.

Cáceres told SciDev.Net in an email that the study highlighted the biological and evolutionary dimensions of sound, something that previous evaluations have not considered in depth.

The marine biologist and regional representative of the Sustainable Ocean Alliance says the research “helps to clearly explain why deep-sea mining is incompatible with conservation commitments … and emphasises, for the umpteenth time, the need for the moratorium that Latin America has been leading”.

With deep sea mining on the rise, the research comes at a critical time.

To date, the International Seabed Authority has granted 31 exploration licenses — 17 of them in the CCZ — and is under pressure to approve a code that would allow commercial exploitation.

In April, US President Donald Trump issued an executive order for the country — which is not a member, but an observer in the International Seabed Authority — to advance the exploitation of minerals in international waters.

However, more than 30 countries, including several in Latin America, oppose this extractive activity and call for a moratorium, according to the Deep Sea Conservation Coalition.

Opponents argue that high-impact industrial activity should not be allowed without solid scientific evidence to guarantee that there will be no irreversible damage.

Alejandro Olivera, Mexico representative of the Center for Biological Diversity, told SciDev.Net: “The challenge now is to get humanity to agree to protect a heritage that belongs to everyone.

“These are ecosystems that we don’t even know about, where we would be destroying forms of life that we have not yet discovered.”

This piece was produced by SciDev.Net’s Latin America and Caribbean desk.