Environmental threats of seafloor mining to the Twilight Zone

Mining-generated sediment plumes and noise have a variety of possible effects on pelagic taxa. (Organisms and plume impacts are not to scale.) Image credit: Amanda Dillon (graphic artist)

A team of researchers from a wide range of oceanographic research centers worldwide recently published an opinion article in the Proceedings of the National Academy of Sciences (PNAS) that concludes seafloor mining has the potential to significantly disrupt the ocean’s twilight zone. Despite this, very little consideration is given to mid-water ecosystems when evaluating the environmental risks of deep-sea mining. They write:

[R]esearch indicates that seafloor mining will generate sediment plumes and noise at the seabed and in the water column that may have extensive ecological effects in deep midwaters, which can extend from an approximate depth of 200 meters to 5 kilometers. Deep midwater ecosystems represent more than 90% of the biosphere, contain fish biomass 100 times greater than the global annual fish catch, connect shallow and deep-sea ecosystems, and play key roles in carbon export, nutrient regeneration, and provisioning of harvestable fish stocks. These ecosystem services, as well as biodiversity, could be negatively affected by mining.

Read more:

Drazen J.C., et al., “Midwater ecosystems must be considered when evaluating environmental risks of deep-sea mining,” PNAS, published online July 8, 2020.