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The sky was moonless and cloudy, with no stars to guide. Alone at the helm in the middle of the Arabian Sea, somewhere between Oman and India, I could see nothing in the ink-black night except the dimly lit compass of our ship, which rolled on its gimbal as we rose and swayed through three-meter seas. But half an hour after my shift, the sails above me began to glow, as if the moon had risen. But there was no moon, no stars, no other ships. The light seemed to come from below and grow. Soon the whole ocean was glowing green, but dim, as if the light shone through a sea of milk.
It was August 2010 and I had been sailing for more than two months, volunteering with the NGO Biosphere Foundation to deliver Mir, a 35-meter wrestler they had recently bought in Malta, back to their home port of Singapore. During the trip, I was accustomed to the usual “sea glow” caused by dinoflagellates, which ignite when water is shaken, causing light bands to twist from Mir’s nose. But that was not it. It was the whole ocean, as far as I could see, glowing in a uniform, opaque green. Although the compass was still spinning in its stand, the light in the water created an optical illusion, making the sea look completely calm, as if we were gliding through phosphorescent skies, not stormy seas.
I woke up the rest of the crew and for more than four hours we were engulfed by this sea of green light, stunned, with no idea what we were witnessing. Finally, a razor-sharp line appeared in front of us, where the shining sea ended and blackness began. Crossing it, we left behind that numinous phantom world and re-entered a familiar one, although we could still see the transparent green glow of our stern for another hour before it disappeared. Only when we arrived at the port 10 days later would we learn the name of the sinister phenomenon that had surrounded us: the Milky Sea.
In August 2010, author Sam Keck Scott and his crew were sailing in the Arabian Sea when they became one of the few people to witness the Milky Sea. The photo was provided by the Biosphere Foundation
For centuries, sailors have described milky seas, rare cases in which vast ocean expanses shine evenly at night, sometimes stretching to tens of thousands of square kilometers or more. NI Kingman, captain of the Shooting Star clipper, had the following to say when he witnessed one in 1854: “The stage was one of awful greatness; the sea that has turned to phosphorus, the skies hanging in black, and the stars that go out, seem to indicate that all of nature is preparing for the last great fire we have been taught to believe is to destroy this material world. ”
The Milky Sea even appeared in Moby Dick, where Melville describes a sailor sailing through a “veiled phantom of bleached waters” that was “terrible to him like a real ghost.”
Neither our small crew, nor Melville, nor Kingman knew what caused the brilliance of the seas. In 2010, our crew had the advantage of living in a world far better defined by science than in the 1800s, which may explain why the sailor Kingman and Melville responded with god-awful terror as we stared in amazement, knowing that no matter how transcendent this phenomenon may seem, it was clearly from this world.
Bioluminescence – the emission of light from a living organism – is a common phenomenon on our planet and nowhere more than in the oceans. Bioluminescent fish, membranes, dinoflagellates, crustaceans, mollusks, jellyfish and bacteria glow and flash in our seas at night. But the Milky Sea, though so vast, is anything but common and is thought to be caused by one of the smallest organisms in the ocean.
Every observation of the Milky Sea throughout history has been a chance encounter, like mine, and has only happened once on a ship with any scientific research, when the USS Wilkes sailed the Milky Sea for three consecutive nights outside the island. Socotra, Yemen, in 1985. On board the Wilkes was the late marine biologist David Lapota, who at the time worked for the Navy and studied bioluminescence. Lapota and his team of researchers took samples of the water and found an abundance of the bioluminescent bacterium Vibrio harveyi – a common, well-dispersed species known to be luminescent – attached to pieces of algae, leading them to speculate that legions of this bacterium and potentially other bioluminescent bacterial species are also the cause of the milky seas. This study, conducted nearly 40 years ago, remains the only time the Milky Sea has ever been studied in this area.
There are no existing images of the Milky Sea in nature, but this sample of bioluminescent bacteria demonstrates the uniform radiance of the phenomenon on a small scale. Photo courtesy of Steve Miller
If we assume that scientists are right that the Milky Sea is caused by bacteria, the question remains: why? Unlike many organisms that have developed bioluminescence as a means of escaping predation, bioluminescent bacteria want to be eaten – the inside of a fish’s gut provides a more secure home than free navigation in the open ocean. But a solitary bacterium is probably too small to attract the attention of fish on its own, so in order to express their microscopic bioluminescence on a macro scale, they require strength in numbers. To work together, each bacterium releases a chemical signal to sense if other bacteria are nearby, and only after recognizing a sufficient number – scientists estimate a population of somewhere between 10 and 100 million bacteria per milliliter of water – will it glow. . This is a process called quorum sensing, and may explain why milky seas form.
In rising areas, such as the northwestern Indian Ocean, where an abundance of nutrient-rich, decomposing organic materials – such as pieces of decaying crabs or even spots of long-dead whales – are pushed to the surface from the depths, bacteria will find much to colonize. When these rich waters are isolated due to currents or when individual masses of water with different salinities or temperatures meet and form physical fronts, they can prevent mixing, which in turn can lead to something like a concentrated stew – what scientists have called ” hypothesis for a natural flask. “In this scenario, by taking into account the quorum, these bacteria cause chemical glow, which can become the greatest manifestation of bioluminescence on the planet.
This idea of a natural flask may help explain why, when our boat first sailed into the Milky Sea, the light was dim and almost invisible, but when we got out of it hours later, we crossed a clear line. On the one hand, this particular event mixed luminous and non-luminous waters, while on the other hand, due to some ocean front, a wall-like barrier was maintained between specialized – and little understood – conditions that allow the formation of milky seas and conditions that do not. they do. This is just one of many things that scientists hope to understand better through further study of the Milky Sea in this area, which, thanks to a new generation of satellite technology, may soon become possible.
Steve Miller, director of the Cooperative Institute for Atmospheric Research, is part of a small group of scientists who have been working to demystify the Milky Sea for nearly 20 years, searching for it from the most incredible location: Fort Collins, Colorado. He was the first person to discover the Milky Sea from his office.
Miller contacted me shortly after I wrote a blog post about our experience sailing the Milky Sea, informing me excitedly that the crew of our ship is among the few famous people today who have witnessed it. Our short correspondence made me feel like a minor celebrity.
Miller first became interested in the Milky Sea in 2004 while attending a conference of the American Meteorological Society. There, Miller and his colleagues considered whether it was possible to observe some kind of marine bioluminescence from space. Every small bioluminescence, like a sea spark, was thought to produce too weak a light signal to be seen from so far away. But Miller, intrigued by the idea of studying the sea from space, did some research when he returned home and was amazed to find dozens of surprisingly consistent stories of so-called milky seas given by sailors over the centuries. An atmospheric scientist by education, Miller wondered if he could use historical satellite data to locate one of these events. It didn’t take long for him to find what he was looking for: a detailed account of the Milky Sea seen by the SS Lima crew off the coast of Somalia on January 25, 1995. The bill lists the exact coordinates and time the boat entered the event. Using the course and speed of the ship’s log, Miller was able to extrapolate Lima’s position as the crew claimed to have left the glowing waters six hours later. He drew the dots, date, and time on the image and zoomed in on a grainy black-and-white photo. “Everything was black,” he tells me.
Without worrying, Miller decided to reduce the image a little more, searching the noise for a photo taken more than 800 kilometers away. Suddenly, a small structure appeared in the center of his computer screen, which he initially mistaken for a fingerprint stain, but when he moved the image, the stain moved with it. It increased a little more and a comma appeared in the waters of the Horn of Africa. When he superimposed the ship’s coordinates, they were exactly aligned with the comma. “That’s when we realized we had something,” he said. The shape, larger than Connecticut, was more than 15,000 square kilometers of glowing bacteria.
“I was caught by …
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