Mining sediment plumes smother benthic fauna kilometers from mine sites

When nodule collector vehicles operate on the seafloor, they disturb 2.5 to 5.5 tonnes of sediment for every tonne of nodules collected. Field tests (including the 2021 MiningImpact2 experiment) show that this sediment forms a gravity current that channels through seafloor depressions and travels 500+ meters downslope, while bottom currents carry suspended particles laterally with concentrations up to four orders of magnitude above ambient levels measured at 50 meters from mining lanes. The particles -- clay, silt, and fine organic matter -- resettle on the surrounding seabed, burying filter-feeding organisms, clogging respiratory structures of sessile fauna, and smothering microbial mats. Post-disturbance surveys document a 37% decrease in macrofaunal density and 32% drop in species richness within mined tracks, with impacts detectable well beyond the directly mined area. This problem persists because no engineering solution currently exists to collect nodules without disturbing the surrounding ultra-fine abyssal sediment, which has accumulated undisturbed for millions of years and has physical properties (extremely low density, high water content) that make it uniquely susceptible to resuspension.