Sometimes the sailors’ myths aren’t far off: The deep ocean really is filled with treasure and creatures most strange. For decades, one treasure—potato-size nodules rich in valuable metals that sit on the dark abyssal floor—has lured big-thinking entrepreneurs, while defying their engineers. But that could change April 2019 with the first deep-sea test of a bus-size machine designed to vacuum up these nodules.

The trial, run by Global Sea Mineral Resources (GSR), a subsidiary of the Belgian dredging giant DEME Group, will take place in the international waters of the Clarion-Clipperton Zone (CCZ), a nodule-rich area the width of the continental United States between Mexico and Hawaii. The Patania II collector, tethered to a ship more than 4 kilometers overhead, will attempt to suck up these nodules through four vacuums as it mows back and forth along a 400-meter-long strip.

Ecologists worried about the effect of the treasure hunt on the fragile deep-sea organisms living among and beyond the nodules should get some answers, too. An independent group of scientists on the German R/V Sonne will accompany GSR’s vessel to monitor the effect of the Patania II’s traverses. The European-funded effort, called MiningImpact2, will inform regulations under development for seafloor mining,…

The nodules are abundant, and they are rich in cobalt, a costly metal important for many electronics that is now mined in the forests of the Democratic Republic of the Congo, a conflict zone…Ideal for nodule formation, the CCZ is estimated to contain some 27 billion metric tons of the ore. But its abyssal plain is also a garden of exotic life forms. Craig Smith, a benthic ecologist at the University of Hawaii in Honolulu, has helped lead biological surveys in the CCZ that, in one case, revealed 330 species living in just 30 square kilometers, more than two-thirds of them new to science. The CCZ’s inhabitants include a giant squid worm,  green-yellow sea cucumbers that researchers called “gummy squirrels,” and a greater variety of bristle worms than ever reported before.

Mining could leave a lasting imprint on these ecosystems. In 2015, MiningImpact scientists visited the site of a 1980s experiment off Peru in which a small sledge was pulled along the bottom to simulate nodule harvesting. Three decades later, “It looked like the disturbance had taken place yesterday,” says Andrea Koschinsky… Many of the species in the deep seabed, such as corals and sponges, live right on the nodules. “They will be sucked up and are gone. You can’t go back.”Such concerns make many environmentalists wary of opening any of the deep sea to mining…

For one thing, the legal framework for mining in international waters is uncertain. Although the United Nations’s International Seabed Authority has granted contracts for exploration, it is still drafting rules that will govern commercial operations and set limits for environmental damage. The rules are unlikely to be final before 2021…

These sensors will focus on the plume of sediment the collector kicks up. The waters of the CCZ are some of the clearest in the world, and scientists have long feared that mining could spread a vast blanket of silt, hurting life far outside the mining area. Recent experiments, however, suggest most of the silt particles will clump together and fall out within a kilometer or two, Koschinsky says. But a film of finer nanoparticles might spread farther.

Excerpts from Scheme to Mine the Abyss Gets Sea Tria, Science,  Mar. 15, 2019