Last March, the National Oceanic and Atmospheric Association exploration vessel Okeanos made a remarkable discovery while surveying the deep sea floor off of Hawaii. In the pale bright light of a remotely operated underwater vehicle's (ROV) floodlights, a purplish form appeared—an unknown species of octopus. The little gelatinous blob staring back at the camera became somewhat of an internet sensation and earned the endearing nickname "casper."
Unfortunately, the deep sea environments where these beloved octopods live are going to be under serious pressure in the very near future. Casper and many other deep dwelling sea creatures make their livelihoods in undersea plains littered with metallic nodules of manganese, nickel, zinc, copper, gold and more—metals in high demand partly because of their use in electronic devices like smartphones. Mining companies have hungrily eyed these mineral rich regions for decades, but have never been able to reach them until now. With cost effective technology finally available to bring nodules up to the surface, organisms like the casper octopus, so long sheltered from human activity, are going to find themselves in danger.
Polymetallic nodules are potato-sized hunks of metal that form much like a pearl does in an oyster. Over time—millions of years maybe—metal bits coalesce around a tiny object (strangely, the most common seed of these nodules is a shark's tooth). There's some argument over how long it takes them to form, but ecologist Autun Purser of the Helmholtz Centre for Polar and Marine Research in Germany, told Motherboard that "these things are like half a millimeter thicker than when Napoleon or Julius Caesar was walking around. So they're very slow to form."
"These things are like half a millimeter thicker than when Napoleon or Julius Caesar was walking around. So they're very slow to form."
"They're always in deep waters and are distributed across all the major oceans of the world in varying densities," said Purser, but he noted that wide deep sea basins 3000 - 6000 meters deep in the Pacific and Indian oceans, can have some very high densities. The Clarion-Clipperton Zone in the Pacific Ocean contains an estimated 21 billion tons of manganese nodules and covers an area the size of Europe.
Nodules lie loosely in the sand, but because they exist in places devoid of any other hard substrates—just muddy sediment—they end up acting like pseudo-reefs. Sponges and other sessile creatures can anchor themselves to the metallic rocks. They in turn provide habitat for a wide variety of other deep sea organisms. "Any complexity in the seafloor adds more habitat niches," said Purser. More niches, more friends.
An array of large, mobile creatures like sea cucumbers, deep-sea prawns, deep sea fishes, brittle stars (crazy looking starfish with spindly arms) and the beloved casper octopods spend their days in and around the nodule fields, foraging and reproducing. In a paper released this week in the journal Current Biology, scientists (including Purser, one of the paper's co-authors) described how the ghost-like octopus lays its eggs on the dead stalks of sponges affixed to manganese nodules. The mother broods these eggs on the sponges until they hatch, which can take years.
Beneath the muddy sea floor exists a menagerie of squirming organisms living and dying in the muck. "There is a lot of biomass within that mud," said Purser. Crabs and mussels, spiky bristle worms, and many-legged copepods are some of the organisms that call the sediment home—and also probably make a nice meal for the casper octopod digging around in the mud with its tentacles.
Purser believes the octopod to be an apex predator in these nodule environments. "The number of eggs it laid on these nodules was quite small, which usually means that an animal has a long life and not too many predators," he said.
These secret, dark dwelling communities are about to be invaded by large machines, however. Over one million square kilometers of ocean floor, between 800 and 6,000 meters deep, have been earmarked for exploration by mining companies. "It's coming very soon," said Purser. Maybe even within the next year.
Not only will the sea sponges and the other unique animals living directly on the nodules be killed, but as is evident with the casper octopod, other mobile creatures will be negatively affected as well. If the nodules are removed, then the sponges on which it relies to lay its eggs will be gone as well. And removing an apex predator like the octopod will have knock-on effects of its own—upending the balance of the sea floor ecosystem.
"Species are found there and nowhere else on the planet, and many of the species are just getting discovered."
The machines mining companies are likely to use resemble giant potato harvesters. These giant 300-ton robot tractors trundle along the seafloor, ploughing through the sediment, scooping up manganese rocks. The resulting clouds of mud agitated by such a disturbance could be devastating to the fauna that live within it and in the water column. Such machines could even contribute to climate change by shaking up the natural carbon storage processes in the ocean. Woe to the octopod that gets in a robot's way.
"These are often very ancient, very slow-growing ecosystems," Douglas McCauley, director of the Benioff Ocean Initiative and marine biologist at UC Santa Barbara, told Motherboard earlier this year. "Species are found there and nowhere else on the planet, and many of the species are just getting discovered. So, the prospect that you are going to grind a road on that space and then roll one of these 300-ton robots over the top of it and suck it all out—that makes a few alarm bells go off in terms of what the impact would be."
Since so little is known about these mysterious ecosystems it'll be hard to get any protective legislation before extraction starts. "The companies that are inventing these technologies are playing their cards very close to their chest," Purser lamented, so the International Seabed Authority of the United Nations will have to be proactive in putting forth the protection required when the time comes. Hopefully it won't be too late.
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