Title: Noise from deep-sea mining in the Clarion-Clipperton Zone, Pacific Ocean will impact a broad range of marine taxa

Authors: Williams et al.

Journal & Year: Marine Pollution Bulletin, 2025

BLUF: Williams et al. offer one of the first systematic syntheses of how continuous industrial noise from polymetallic-nodule mining could permeate the entire water column of the Clarion-Clipperton Zone (CCZ). Their meta-analysis shows that only about one-third of the animal classes already catalogued in the CCZ have ever been tested for noise sensitivity, yet many of those that have, display clear behavioral or physiological disruption. Without transparent disclosure of prototype sound signatures and an ISA-endorsed acoustic standard, environmental impact assessments will be flying blind — an avoidable risk for an industry that prides itself on engineering rigour.

Much of the public conversation around deep-sea mining still centers on visible plumes and seafloor scars. Williams et al. rebalance that narrative by tracking sound, the ocean’s primary information channel.

They screened nearly 3,000 publications, distilling 373 data-rich studies down to the subset relevant for CCZ species. Study settings were almost evenly split between laboratory tanks and field deployments, underscoring how little pressure-controlled, deep-sea work has been done.

The outcome is sobering: continuous low-frequency machinery noise (< 200 Hz) emitted by collectors, riser booster pumps and dynamically-positioned surface vessels is predicted to couple with the SOFAR channel at roughly 1 km depth and propagate for hundreds of kilometres.

Their Figure 1 — a cross-section that layers mining hardware and representative taxa from the surface to 6,000 m — visualizes this acoustic footprint far more intuitively than any decibel table could.

Equally striking is Figure 8, a bar chart revealing that deep-sea invertebrates are almost absent from existing noise studies. Only 35 % of the 52 taxonomic classes known from the CCZ have been examined at all, and many experiments were run in shallow aquaria that ignore in-situ pressure or particle motion, limiting their realism.

The authors therefore caution regulators against importing coastal noise thresholds wholesale; instead, they map a research agenda focused on true deep-sea conditions and chronic, not just acute, exposure.

They single out the CCZ’s diverse but poorly studied soniferous fishes and call for a network of long-duration acoustic observatories to track baseline soundscapes before full-scale mining begins.

Williams et al. close by noting that the CCZ remains one of the quietest industrial frontiers on the planet; its ambient soundscape is still dominated by wind, distant whales and the occasional seismic survey. The opportunity, then, is to embed acoustic stewardship from day one — avoiding the retrospective clean-up that has plagued many coastal industries.