The deep sea – salvation or ruin?

 kw: book reviews, nonfiction, oceanography, sea life, bioluminescence, seabed mining, polemics

The red tide can be beautiful at night. The tiny animals, so toxic in large concentrations, are also luminescent, flashing when they are disturbed. In the red tide season—when it isn't safe to swim anyway—the best time to watch the surf is late at night, when the waves flash and glow with green and blue colors. That's the only kind of bioluminescent sea life I have seen.

Oceanographers and marine biologists (such as my supervising curator at the DE Museum of Nature and Science) get to see much more, at least through the video eyes of underwater robotic vehicles (ROV's), such as this one shown in an advertising image. Studies using ROV's are finding entire ecologies that nobody knew could exist, and they exist right down to the bottom of the deepest trenches in the sea floor, up to seven miles down.

But in midwater, where it is safe to do so, when they turn off the lights, it isn't all the stygian darkness of the deep ocean. They see sparks of light everywhere. It may be that bioluminescence is the rule, not a rarity, among sea creatures.

This montage of images shows some of the branches of the tree of life that include well-lit creatures. Clockwise from top left, a "firefly squid", one of many squids that light up (and other cephalopods such as cuttlefish can also do so); a jellyfish; a small shark, with lights that help it "vanish" against the light from above; and a siphonophore, of the same phylum as jellyfish but sort of like a coral colony without the rocky shell (this species gets more than 100 feet long, longer than the largest whale).

The discovery of deep water habitats and the creatures that live there are lovingly described in Part One of The Brilliant Abyss: Exploring the Majestic Hidden Life of the Deep Ocean and the Looming Threat That Imperils It, by marine biologist Helen Scales. It is interesting that species of fish and insects that become permanent inhabitants of caves have lost their eyes, yet deep in the ocean, most creatures have eyes, and in some cases, eyes that can see in not just three colors (as we can), but ten or more. In the deep ocean, they don't see by sunlight, but they see each other.

Deeper than 200m (~650 feet) in clear ocean water, there isn't enough light for our eyes to see, but some ocean creatures have eyes that see by the trickle of light that reaches as deep as a kilometer (~3,300 feet). The upper 200m includes just 7% of the oceans, and the upper kilometer contains about 30%. Yet in the deep abyss, from 1km to 11km, there are eyes everywhere, and there is plenty for them to see, including friend and foe, mates and prey. There are squid that, when threatened, squirt a blob of glowing ink, turn off their own lights, and jet away. Anglerfish bob glowing lures to draw in prey, while hatchetfish put on a variety of light shows, which some think could be communication. Some animals light their whole body and then darken smaller areas, like characters on a computer screen.

Part Two of the book describes the slow flow of ocean currents, and then discusses the possibility that cellular life arose in the deep sea, at or near places where the heat from below breaks through at the deep-ocean ridges and hot spots such as the one that has formed Hawaii and its island chain for millions of years. The author goes on to tell of medicinal uses for chemicals found in deep sea life. In the chilly depths, where food is more sparse, we find corals and other creatures that are hundreds, and perhaps thousands, of years old. Living slowly, but persistently. Some have special proteins that help them resist incredible pressures that literally bend the molecules of life out of shape (and shape is what makes a protein do its job). Some have other components that heal wounds, protect tissues from decay, or fight microbes, and some of these have found pharmaceutical uses.

Part Three delves through the history of our "use" of the oceans, both extractive (fishing and whaling, for example) and as a repository for our waste. That latter isn't just the oceans; when I lived in Cleveland in 1961, the "sewage system" consisted of pipes five miles long that took raw sewage into the middle of Lake Erie! A north wind would bring turds ashore. Coastal cities worldwide used to do the same. There are areas of dumped radioactive waste. Do you fancy eating fish caught in those waters?

The third and last chapter of Part Three introduces seabed mining. Interesting "stuff", potentially valuable "stuff" has been found in three areas:

• The abyssal plains, at an average depth of several kilometers, include large areas carpeted with nodules made up of metallic oxides. The most abundant metal is manganese, which isn't particularly valuable, and iron is second in abundance, but they also contain cobalt, nickel and copper, and a little chromium. These are valuable, but make up only a few percent. A typical nodule the size of a walnut took several million years to form. Their composition varies from place to place, depending on what is available in the regional seawater.
• The "caps" of seamounts, their upper few meters, contain a similar suite of metal oxides. There may be a million or more seamounts, most of which are extinct volcanoes. Although their "caps" constitute only one or two percent of the sea floor, they are thick and would be easier to mine for minerals, compared to the abyssal plains.
• Vent communities form on and near the crests of the midocean ridges, which form a chain 40,000 miles long, or 65,000 km. The superheated, mineral-laden water that flows from "black smokers" and "white smokers" (in cooler areas) builds up "chimneys" of metal sulfides and metal oxides, which are like concentrated ores.

Each of these is being considered as mining targets for future exploitation, and some experiments have been performed. So far, the economic story isn't all that attractive, but that hasn't stopped the momentum of the undersea mining interests.

The biggest targets are the nodule fields on the abyssal plains. This area near Tonga is about average. Some places are so densely covered one can hardly see the sand between the nodules.

Just as on land, however, areas that contain desirable "stuff" are already inhabited. A careful look at this image shows whitish spots and blobs, which are some of the larger creatures that live, not just among, but rooted onto, nodules. I carefully scanned a larger version of this image, and found about 100 creatures. Many more are smaller or have a darker color. Most likely, every nodule has something living on it.

Part Four discusses the need to preserve the deep sea and all the habitats included within it. This montage, from a scientific article in ResearchGate, shows some of the creatures that live among metallic nodules in the Clipperton Fracture Zone, a prime target of mining interests.

Here the author becomes quite polemical, in a very good way. We must admit that we know only a tiny fraction of what is going on in the deep sea. We do know that it regulates global temperature, buffers the rise and fall of carbon dioxide in the atmosphere, and either preserves or destroys the great ice caps in north and south. Do we know enough to disrupt it with impunity?

The author points out the few very valuable pharmaceuticals that have been found in deep sea creatures, and the promise of whole new classes of antibiotics, for example. I find it a shame that the "Save them to make future drugs" argument is used so frequently, by many, many authors, not just De. Scales. Is there none other? Is there no way to persuade mining interests to hold off, besides trying to counter one financial interest with another? Is money the only bottom line that matters?

Sea bed "resources" are not renewable, not on a human scale. Vent communities take thousands or tens of thousands of years to form; a potato-sized nodule took 10-20 million years to form; the "cap" of a seamount may have grown over 100 million years. Every extractive technology grows exponentially. What is costly and difficult today gets easier and cheaper with time. People always say, "We won't take everything." It's a lie. Of course we will.

There's an apocryphal story of a Canadian chief talking with a geologist who is exploring in his tribal area. He said, "When white men first came to Canada, they shot all the big game and hauled away the meat. Later, more white men came to trap all the smaller animals, and they hauled away the furs. The next time white men came, they cut down the big trees and hauled them away for lumber. Then, other white men came to cut down the smaller trees, and hauled them away to make pulp for paper. And now here you are, coming for the rocks!"

To a scientist, the only reasonable path is study first, before mining anything. I don't expect that to happen.