The light show far below

 kw: book reviews, nonfiction, oceanography, bioluminescence, memoirs, giant squid, architeuthis

When I lived in southern California I frequently went to the beach; my favorites were Huntington Beach and Laguna Beach. In the summertime there are periodic red tides, and when the water is visibly red, it isn't safe to swim. However, that is when it is nice to visit the beach at night to see glowing blue waves. The red tide creature is a type of dinoflagellate (a single-celled protist) that is also bioluminescent. When agitated, the critters glow or sparkle blue.

In Below the Edge of Darkness: A Memoir of Exploring Light and Life in the Deep Sea, author Edith Widder, PdD tells of the many marine creatures that glow, in many, many ways. In the deep sea, below the limits of sunlight, most animals make their own light. This in itself explains an early mystery: no matter now deep one sent a trawling net, many of the animals brought up had eyes. What are they observing? In this book we learn that there is a lot to observe down there!

Dr. Widder was one of the first persons to descend (in a submersible, of course) into the sea deeper than sunlight can reach, and turn off the lights. Whoever does this for their first time has the same reaction, "It's like a sky full of fireworks!". Yet, just after seeing that, when the lights are turned back on, you typically don't see anything! What gives?

Consider the dinoflagellates that light up the waves along many coastlines. A typical bioluminous dinoflagellate is between 20 and 40 microns in diameter. That's the size of the cells that make up the inside of your cheek. If you use a teaspoon to gently scrape the inside of your cheek, put a drop of the result on a microscope slide and look at medium power, such as 100x, you'll see a bunch of rather blobby cells that appear about an inch across or so, with slightly darker nuclei the size of a BB. Pull the slide out of the microscope and look at it. Just a bit of slightly milky fluid. Nothing you can see distinctly. Yet a single dinoflagellate, the same size as those cheek cells, can make a flash of light that can easily be seen in the dark. Thus, if your sub is surrounded by microbes, you won't see them with the lights on, but in the dark, the flashes they are making because of the disturbance caused by your sub makes the water itself seem to sparkle.

If you so see something, it is likely to be a jellyfish such as this one. Jellyfish and related animals called siphonophores are frequently bioluminescent.

Siphonophores in particular can be so transparent that, even if one is right outside the sub window, you may not see it right away…with the lights on.

What is the purpose of all this light in the deep sea? Three big things, and a host of lesser reasons. The big three: to find food, to avoid being eaten, and to find a mate.

Finding food: Some bioluminescent fish have "flashlights" near their eyes, little organs filled with bioluminescent bacteria, which they feed and care for. The light organs have shutters so the light can be blocked. Many deep sea animals respond to a flash of light with their own flash, so the hunting fish will make a quick flash, and decide among the return flashes if any are worth trying to eat. Whether or not it goes for a meal, it will jerk away, so the flash it made will not let a bigger predator know where it is. Many fish have light organs at the end of appendages where they act as lures to draw in a hungry animal, but it quickly becomes lunch itself. Angler fish are the best known purveyors of this hunting strategy.

Predator avoiding: The flash-and-jerk technique is one way to hunt without being hunted successfully. Another is counter-illumination. Creatures that spend much time near the edge of twilight but not below it could be seen from below unless they employed a little bit of light, shining from their bellies, to mimic the light that would be shining if they weren't there. A similar technique was studied by the U.S. Air Force in the 1970's. A project I worked on briefly studied how well we could see a cluster of lights set against a simulated sky. The idea was to fool the gunners of an antiaircraft battery, who might barely hear a high-flying bomber, but the counter-illumination would make the bomber effectively invisible. It didn't work very well, for two reasons: Firstly, human eyes have very high resolution, so the aircraft would have to have a great many closely-spaced lamps so it wouldn't look like a speckled "something" up above. Secondly, human eyes have excellent color discrimination, and the color of the sky is variable, even varying in different directions at a given time. Thus, lamps of one color that make the plane invisible when seen from directly below, might not work that well to one side or the other. A third nail in the project's coffin: polarizing sunglasses darken the sky, making such an illuminated aircraft more visible than if the lights were left off! Deep-sea fish don't have color vision, and they don't see as clearly, so a cluster of a dozen or two dozen light organs of any bluish or blue-green color, of appropriate brightness, can be an effective invisibility cloak.

Another method to avoid becoming lunch is to make very bright "burglar alarm" flashes when attacked, hoping to bring a bigger predator to drive off or consume whatever is eating you. The Jellyfish Lamp used by Dr. Widder to attract predators in the deep sea emulates a common distress display.

Mate location: Fireflies do this. Those of us living east of the Rockies in the US, and people in many other places worldwide, are familiar with these greenish lights in our yards in June (or December in the southern hemisphere): male fireflies "calling" for females, which don't fly, but rest among vegetation and answer the lights they see with lights of their own. So-called "sea fireflies" (tiny shrimplike ostracods, 1-2 mm long) have a similar mating process, as do a number of other deep water animals. The trick is to make a flash during a turn, to make it harder for a watching predator to locate, similar to hunt-and-jerk.

The last chapters of the book tell the tale of finding and filming giant squids for the first time using a more advanced Jellyfish Lamp named Medusa along with a baitfish to keep the predator busy for a moment. It worked spectacularly well. The montage below shows two images of the attack of a young giant squid on the bait. This squid was "only" ten feet mantle length, with tentacle length estimated at 15-20 feet.

Giant squids that are seen at the surface of the ocean are either dying or dead, and are always red. They float because they have ammonia in their tissues, so they don't need to swim to keep from sinking deeper and deeper. The have to swim to stay down. They are red because they have lost active control of their chromophores. Living, healthy giant squids in the videos these images come from look metallic, with colors of silver and bronze (bronze may indicate alarm), and you can see stripes on the arms.

The videos of these encounters made lots of people very famous, including Dr. Widder. I hope it gives her enough of a platform to advocate more effectively for ocean conservation, along with Sylvia Earle and younger leaders such as Luis David Calderon and Maggie Seida. In her last chapter she tells some compelling stories, including the saga of Georges Bank. This underwater plateau, larger than Massachusetts, has been fished into oblivion. It was once rich with a very diverse ecosystem that included several commercially desirable fish species. Fast-forward a couple of generations. Only after nothing of value was left to catch did the area receive governmental protection. The quantity of life is probably now similar to what existed in the early 1900's, but it is nearly all jellyfish. Not only are the fish gone, including jellyfish-eating swordfish, so are all other jellyfish eaters such as sea turtles. Now that the "cats" are all away, the jelly-mice are out to play, by the trillions. Leaving the place alone may eventually lead to a return to ecological health, but there is a "new normal" at present, and it's pretty stable.

Can we learn enough about the ocean, not just to preserve what's valuable, but to even know what is valuable and needs preserving? The world ocean has been humanity's waste dump and scrounging venue for centuries, even millennia. Now that humans number 8.1 billion, is going back even possible? We spend more on each new NASA venture (all of them much needed!) than the total amount reserved for oceanographic research yearly. A very visible program called Sea Grant has a budget of $90 million. That's "million" with an "M". Compare that to $7.4 billion being spent to "forgive" some student loans. Go ahead, divide the numbers: it's 82 times as much. I'll stop here and let my blood pressure subside.

Whew! I love this book. Get it and read it. Then search "bioluminescence" with your favorite browser and read some more. It can open a new universe to you.

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.