Environmental Impact

There is a significant environmental issue with mining (and to a lesser extent dredging) active hydrothermal vents. There are a number of marine creatures that depend on the heat and the minerals ejected from these vents to survive. Bacteria feed on the sulfur and other minerals in the events, plankton and other small critters feed on the bacteria, then tube worms, corals, shrimp, crabs, mussels, and a variety of larger creatures feed on the bacteria and plankton. Each vent hosts a unique variety of creatures, and some of the creatures that have been identified exist literally nowhere else on earth but the single vent site where they were found. Pretty much every time a biologist studies one of these vent sites there are at least a few new species discovered. So it’s not hard to imagine that ripping up the rocks and hydrothermal chimneys at these vent sites would interrupt if not completely massacre these unique ecosystems. Dredging is unlikely to have as large of an effect because it wouldn’t destroy the whole site and it would most likely recover over a matter of months to years. But mining the area in the way that Nautilus plans to would likely cause irreparable damage to these delicate sites. The good news is that these vents typically only have a natural life span of a few years to maybe a few hundred years, but it’s impossible to predict when they will shut down. As I see it, the “holy grail” for this type of seafloor mining would be a way to reliably identify recently inactive vents which have already died on their own, but this is very difficult to do, because the easiest way to detect them is by the temperature and water column anomalies discussed previously, and those disappear once the vent dies. If we could reliably find dead sites there would be basically no negative environmental impact, but it is difficult to do. The hydrothermal activity alters the rocks, changing both the magnetic and gravity signatures, so these are potential methods for identifying dead vents, but you would have to have pretty high resolution data to find an individual hydrothermal field, and you would have to have some idea of where to look. Another problem with dead vents is that they are quickly buried by sediment, so unless the vents are recently inactive they would have to dig through meters to kilometers of sediment to get to the metals. As of now, they have not actually started mining any vents, and the Nautilus people are aware of the issue, but I doubt the environmental impact alone will stop them when they get to the mining phase.

A crack on the seafloor where hydrothermal fluids are released and mussels live

A picture from the TowCam, showing deep water corals and even a couple crabs

Some less fortunate shrimp that went for a ride in the dredge bag