Sucking the Life out of Deep Sea

Those involved in deep-sea mining hope it will turn into a multi-billion dollar industry. Seabed nodules are dominated by compounds of iron (which is commonplace) and manganese (which is rarer, but not in short supply from mines on dry land). However, the nodules also contain copper, nickel and cobalt, and sometimes other metals such as molybdenum and vanadium. These are in sufficient demand that visiting the bottom of the ocean to acquire them looks a worthwhile enterprise. Moreover, these metals seldom co-occur in terrestrial mines. So, as Kris Van Nijen, who runs deep-sea mining operations at Global Sea Mineral Resources (gsr), a company interested in exploiting the nodules, observes: “For the same amount of effort, you get the same metals as two or three mines on land.”

Though their location several kilometres beneath the ocean surface makes the nodules hard to get at in one sense, in another they are easily accessible, because they sit invitingly on the seabed, almost begging to be collected. Most are found on parts of the ocean floor like the Clarion Clipperton Zone (ccz), outside the 200-nautical-mile exclusive economic zones of littoral countries. They thus fall under the purview of the International Seabed Authority (isa), which has issued 17 exploration licences for such resources. All but one of these licences pertain to the ccz, an area of about 6m square kilometres east-south-east of Hawaii.

The licensees include Belgium, Britain, China, France, Germany, India, Japan, Russia, Singapore and South Korea, as well as several small Pacific island states. America, which is not party to the United Nations Convention on the Law of the Sea that established the isa, is not involved directly, but at least one American firm, Lockheed Martin, has an interest in the matter through a British subsidiary, uk Seabed Resources. And people are getting busy. Surveying expeditions have already visited the concessions. On land, the required mining machines are being built and tested. What worries biologists is that if all this busyness does lead to mining, it will wreck habitats before they can be properly catalogued, let alone understood.

 Some of the ccz’s creatures stretch the imagination. There is the bizarre, gelatinous, yellow “gummy squirrel”, a 50cm-long sea cucumber with a tall, wide tail that may operate like a sail. There are galloping sea urchins that can scurry across the sea floor on long spines, at speeds of several centimetres a second. There are giant red shrimps, measuring up to 40cm long. And there are “Dumbo” octopuses, which have earlike fins above their eyes, giving them an eerie resemblance to a well-known cartoon elephant…Of 154 species of bristle worms the surveyors found, 70% were previously unknown. 

the Whale fossils, sea cucumbers and shrimps are just the stuff that is visible to the naked eye. Adrian Glover, one of Dr Amon’s colleagues at the Natural History Museum, and his collaborators spent weeks peering down microscopes, inspecting every nook and cranny of the surfaces of some of the nodules themselves. They discovered a miniature ecosystem composed of things that look, at first sight, like flecks of colour—but are, in fact, tiny corals, sponges, fan-like worms and bryozoans, all just millimetres tall. In total, the team logged 77 species of such creatures, probably an underestimate.

Inevitably, much of this life will be damaged by nodule mining. The impacts are likely be long-lasting. Deep-sea mining technology is still in development, but the general idea is that submersible craft equipped with giant vacuum cleaners will suck nodules from the seafloor. Those nodules will be carried up several kilometres of pipes back to the operations’ mother ships, to be washed and sent on their way.

The largest disturbance experiment so far was carried out in 1989 in the Peru Basin, a nodule field to the south of the Galapagos Islands. An eight-metre-wide metal frame fitted with ploughs and harrows was dragged back and forth repeatedly across the seabed, scouring it and wafting a plume of sediment into the water…. The big question was, 26 years after the event, would the sea floor have recovered? The answer was a resounding “no”. The robots brought back images of plough tracks that looked fresh, and of wildlife that had not recovered from the decades-old intrusion.

Conservation and seabed minerals: Mining the deep ocean will soon begin, Economist, Nov. 10, 2018

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