Forty years ago, scientists found alien life. Not on another planet, but on Earth, in the deep sea, in places where plumes of steam and nutrients heated by volcanic activity fed entire ecologies of creatures adapted to harness chemical energy rather than energy from the sun.

A submersible takes samples from a microbial ecosystem near a hydrothermal vent in the Juan de Fuca Ridge, a tectonic spreading center located off the western coast of North America.Pilot Mark Spear/Woods Hole Oceanographic Institution

The discovery redefined life’s biophysical possibilities, and scientists and explorers have since charted another world. Or, rather, many worlds: there are more than 500 hydrothermal vent fields scattered across Earth’s seafloors, containing not just the iconic smoking vents but volcano slopes called cobalt crusts and seabed plains known as manganese nodule fields. These are, in a sense, the rain forests and mountains and prairies of the deep sea. Yet that life is now threatened. 

Rich in gold and copper and rare-earth metals—essential ingredients for our digital—hydrothermal vent fields are targets of a nascent deep-sea mining industry that’s slowly but steadily developing the machinery to go after them. Companies and countries have filed prospecting permits or secured mineral rights on 20 percent of the vent fields; the first deep-sea mining operation is expected to break seabed in 2018 off the coast of Papua New Guinea.

It was discovering an alien world, basically, a whole new way of being alive. The knowledge we’ve gained is immeasurable.

That fate of our ocean’s hydrothermal vent fields depends on how carefully they are mined. Mining can be destructive, but it can also be done judiciously, with attention to its consequences on life other than our own. “We’re going to have to make a choice,” wrote deep-sea ecologist Andrew David Thaler on Twitter recently, “between disposable technology and ecosystems we’ll never see.”

Thaler has spent much of his life studying hydrothermal vent fields and their extraordinary life. Nautilus talked to him about whether they might still be saved.

Whats it like trying to get people to care about an ecosystem theyll never even be able to visit in person?

We’re fighting against a long-held belief that began in the 1600s and has persisted since that the deep sea is devoid of life. People think of it as a desert, a wasteland. They don’t think of vibrant communities of exotic animals they’ve never seen. And in general, these aren’t the most charismatic species on the planet. In the ecosystems I particularly love, the western Pacific hydrothermal vents, the dominant species are a couple of snails and squat lobsters. Everybody loves them, though. The yeti crab is a squat lobster, which has been tremendously good for raising awareness.

What makes deep-sea ecologies unique?  

Because they’re so rare, because they’re so spread out, every vent system is different from every other vent system. They have their own different fauna and fascinating patterns of species development. Dynamic ecosystems are the most biodiverse ecosystems. You generally have one or two dominant fauna, then a halo of associated fauna that are exploiting the biomass. When you look at the images, you see these vibrant pictures of tubeworms, and crabs and limpets and snails crawling around them. Then, when you look at some of the slow systems, they’re completely dominated by a single species that has evolved to exploit the niche. But low diversity doesn’t mean no diversity. Low diversity is still rich and vibrant and full of fascinating organisms you’ll never see anywhere else in the world.

Yeti crabs cram into their habitat near a hydrothermal vent in the East Scotia Ridge, located between South America and Antarctica.National Environment Research Council

What have we learned from studying deep-sea vents?

In the 1970s, when we found vents, we saw organisms getting their energy from hydrogen sulfide, but not directly. They build relationships with bacteria that allow them to extract energy. That was the beginning of people even thinking about the microbiome. Now we talk about the idea that humans are mostly bacteria that do bioprocessing for us, that we’re composed of relationships between lots of different organisms. We saw those relationships very clearly and powerfully at hydrothermal vents. So they’re more than a store of resources. They’re a source for inspiration. In fact, before the discovery of hydrothermal vent systems, we had no idea that animals could survive independently of the sun. It was discovering an alien world, basically, a whole new way of being alive. The knowledge we’ve gained is immeasurable.

How do deep-sea vents fit into the bigger picture of life on Earth?

It’s not something we regularly do, but think about the long-term evolutionary conservation of life on Earth. Hydrothermal vent fields represent a completely different way of being alive. If something catastrophic happens, a K-T level event that causes 99.9 percent of life to go extinct, having that diversity of lifestyles safeguards us against the total extinction of Earth-bound life. At some high-end level, the purpose of being alive is to ensure that life continues, right?

What will mining companies send down to the sea floor?

Nautilus Minerals has built some big, Michael Bay-esque machines on the seafloor. As someone who both builds robots and works in deep-sea conservation, I’m amazed and a little terrified. I don’t think there will be autonomous seafloor machines, though. We’re going to be looking at human-controlled vehicles. Some involve dredging up the seafloor. One proposal I saw was just dragging a big bucket across the seafloor and pulling it up, the same way we do strip-mining.

The question becomes: Is there an acceptable loss before we’ve wiped out too much of an ecosystem?

Can the deep sea be safely mined?

Like any mining process, it’s ultimately destructive, but there are ways to do it to minimize the extent of the destruction. Companies are building the tools, laying the groundwork, identifying the ore bodies and target prospects, getting the permits—but nobody’s gone down and actually mined the deep sea. Companies have every incentive to look as green as possible. But until someone goes down and mines, we don’t know if they’re actually walking the walk rather than talking the talk. So the first deep-sea mines will be an experiment.

With deep-sea mining, because conservationists and explorers got there first, we’ve got 40 years of baseline data about the ecosystem including high-resolution seafloor maps and an understanding of populations around hydrothermal vent fields. This gives us the opportunity to think about how to do deep-sea mining right.

Can the ecosystems around deep-sea vents recover from mining?

These are dynamic systems. Some communities, with lifespans of 10 to 12 years, have evolved to handle disturbance. Underwater volcanoes erupt regularly and wipe them out. When we talk about mining a hydrothermal vent, there’s a possibility for the community of life to come back. It’s possible that if you remove just one, then 10 years from now there will be no trace of it being mined at the site—though there is damage to the rest of the seafloor, which is prolonged, because the deep seafloor tends to be undisturbed.

Cobalt-rich crusts and manganese nodule fields, however, are “slow” ecosystems. They can last for centuries. Any affront to a slower system is going to have more consequences. The question becomes: Is there an acceptable loss before we’ve wiped out too much of an ecosystem?

Do you ever wonder whether it would have been better if we never discovered hydrothermal vents?

That question haunts me. Maybe, in some ways, these communities would have been much better off. I don’t think we would have been better off, though. And we already do a lot of damage to the seafloor without seeing it. We drag trawls across the ocean and crush deep-sea coral mounds with dredges so we can bring up fish. So, long-term, I don’t know if not knowing about hydrothermal vents would protect them any more than ignorance protected all the other species and ecosystems we’ve destroyed without having known them.

But the thought does keep me up many nights, wondering what we’ve done by letting the world know about vents. Not knowing what we’ve lost is a lot more tragic, though, than having had the chance to protect something before it goes away.

Brandon Keim is a freelance journalist who writes about science, technology, and nature. His work has appeared in Wired, Aeon, Scientific American Mind, and other publications. @9brandon