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CHAPTER 1
Oceans of Krill
Euphausia — true shining light (Greek)
It was night, and the trawl deck of the Canadian research vessel Dawson was an oasis of light in the inky summer darkness. The ship rolled in the gentle swell, revealing a phosphorescent wake as the stern rose and fell. From the A-frame a single wire stretched taut into the floodlit water, which parted around it in a V-shaped wake as the ship moved slowly forward. At the appropriate signal, the ship's hydraulics groaned into action, and the cable was slowly retrieved from the depths, dripping seawater from the pulley block. A cry of "Sight!" indicated that the net was close to the surface, a pale billowing ghost just visible in the subaquatic greenish light. The drizzling net emerged from the water and was hoisted overhead like an elongated mosquito net. As the wire reached the zenith of the A-frame, the net hung suspended above the glistening deck. The scientific crew sprang into action, using a seawater hose to wash the contents into the net's cod-end — the small container at the end of the net that holds the catch.
Satisfied that every inhabitant of the deep had been flushed into its final resting place in the cod-end, the lead researcher undid the clasp that fastened the cylindrical cod-end to the long, flimsy body of the net. I joined the crowd of eager students on deck as contents were decanted into a plastic tray. "Bugs!" dismissed the professor, as the students enthusiastically poked the rapidly dying catch with tweezers.
A fine-mesh net towed through the water has been standard equipment for sampling the smaller inhabitants of the ocean for more than two hundred years. Because the ocean depths are still one of the planet's great unknowns, there is always a sense of excitement when the contents of a net are heaved onto the deck for examination. The animal life collected in a net has an unforgettable odor — uniquely marine, slightly musty, yet not entirely unpleasant. The animals themselves can vary widely, from wriggling worms to delicate jellies, often crushed and punctured by their unanticipated journey to the surface, to robust amphipod crustaceans that ricochet off the walls of the specimen tray, tiny flealike copepods that twitch their way through the water, and sea snails that appear strangely out of place in the open ocean.
Some larger animals caught my eye — shrimplike creatures that had clearly endured an uncomfortable trip to the surface. These were krill. They lay on their sides, their swimming legs going through the motions, their bodies turning opaque as they slowly died under the glare of the ship's spotlights.
This was my first oceanographic cruise, and my first encounter with living-but-soon-to-be-dead krill. I watched as the tray was whisked away and its contents poured into a jar and topped with formalin — an evil-smelling chemical concoction used to preserve specimens for later analysis. Biological oceanography in the 1970s was essentially this process: dragging a Victorian-era device behind the ship, dispassionately sorting its contents on deck, preserving specimens of interest, and tossing the rest overboard. The exercise was repeated throughout the area of ocean being studied. We gave little thought to the diversity of the sea life we collected, or how the creatures lived and behaved. They were "bugs," zooplankton whose lives were ranked by size, weight, and relative abundance. Through the barrel of a microscope, one animal suspended in formalin looked much like the next.
On a calm day, later that same year, the sun glinted off the gently heaving waters of the Bay of Fundy on the Atlantic coast of North America. Distant flocks of birds hovered above the calmer waters of the oily slicks that meandered across the surface. Our small fishing boat slowly motored toward the signs of biological activity, and I scanned the water for further signs of aquatic life. In the calm, emerald water, rays of sunshine penetrated several meters into the depths of the bay, brightly illuminating surface features, but deeper objects remained indistinct and ghostly. The dense green light of the surface layer distorted the colors of deeper objects. Coastal debris — clumps of seaweed, leaves, twigs, plastic bottles, buoys, and other rubbish associated with fishing communities — had accumulated in the slicks. But below this film there was movement.
Several meters down I could make out a whitish cloud, which gradually turned pink, then red, as it rose to the surface. The cloud became a swarm of thousands of animals with elongated, tapered bodies, swimming in unison and headed in the same direction as if they had a common purpose. As the school neared the surface film, the water turned a rich ochre-red, and I could make out individual krill. Each was about three centimeters (roughly an inch) long, separated by one centimeter from its neighbors. Each probed the water ahead with a set of four antennae, backed up by a pair of bulging black eyes. Krill bodies rippled as their swimming legs propelled them smoothly through the water, their movements perfectly synchronized with those of others in the school. As the krill swarm reached the surface, the school extended their antennae out of the water, and the calm surface rippled from thousands of crustaceans sensing the air. As I watched, mesmerized, this mass of crustaceans became a living, brick-red raft, writhing on top of the water's surface. As if on cue, thousands of krill flipped their muscular tails and leaped clear of the water, falling back like a shower of pink raindrops.
This abundance of densely packaged protein did not go unobserved by the rest of the food chain. The gradual ascent of the krill to the surface was tracked by schools of squid that darted into the aggregations from below, grabbing individual krill with their tentacles, then shooting backward into the ocean's murky depths. Shoals of herring flashed through the krill schools, disrupting their orderly structure and leaving a snowfall of silver scales in their wake. Birds — shearwaters and gulls — squabbled over the smorgasbord of seafood, devouring predator and prey alike. Loud exhalations heralded the arrival of mammals: dolphins and giant fin whales, intent on a meal of krill, fish, and squid, lunged into the krill swarms with mouths agape.
As our boat drifted amongst the swarms of krill and their splashing predators, I watched one long, ribbon-like school of krill moving purposefully past the boat, antennae forward, black eyes prominent, and tails ablur as their swimming legs rhythmically and in unison pushed water away. Each krill maintained a set distance from its neighbors, and the school moved as one — most of the time. As the school passed the boat, one krill broke ranks and swam toward the watching humans, momentarily pausing a meter away. It appeared to check us out before turning around at high speed to rejoin the school.
This first encounter with living krill and their intriguing range of complex social behaviors left me captivated, and the spectacle became my second lesson in biological oceanography. Although routine specimen collection is still scientifically necessary, it became clear to me during this encounter that dead krill under the microscope can provide only part of the scientific story. Preserved specimens allow us to identify and classify anatomical features and conduct important measurements and observations. But just as learning about human life involves more than studying cadavers, learning about krill involves drifting alongside them, entering their world, learning their rhythms and observing their interactions with their swarm-mates and their predators. My attitude toward life in the oceans changed in an afternoon; no longer could I view krill as mere bugs; I was beginning to appreciate their complexity and their beauty.
Given the difficulties of studying life in the open ocean, most marine scientists learn about their subjects by second-hand methods: samples collected in nets, traces on an echosounder readout, or blurred images on an underwater video. There is little capacity to personally observe most animals in the open ocean, or to witness their interactions with the rest of the ecosystem. There are exceptions, however, and in my search for a PhD project, I stumbled across one of them in the Bay of Fundy, a dynamic body of water that separates Nova Scotia from New Brunswick and Maine. According to local ornithologists, krill rose to the surface here in vast numbers each summer and became the food of vast flocks of seabirds. Why? The conventional scientific wisdom of the day conjectured that the massive tidal range, up to eight meters in places, brought krill passively to the surface, where seabirds and whales lined up to feast on these highly visible, calorie-dense treats. But nobody had studied the krill swarms in detail, and I was determined to figure out the mystery. Why would millions of krill take such a suicidal journey in broad daylight?
I spent several idyllic summers searching for an answer, messing around in a small boat with an affable fisherman, chasing krill, catching fish, and watching whales — eventually answering that question to the satisfaction of my doctoral dissertation committee. The answer, like the answer to so many biological mysteries, was sex; the krill were at the surface to mate and lay their eggs. But I could only arrive at this conclusion after several years of sampling, observations, and long hours in the laboratory hunched over a microscope.
My guide and mentor was Ray Thurber, an archetypical wise old fisherman who knew the Bay of Fundy intimately in the old-fashioned way, without the aid of modern instrumentation. He could read patterns in surface waters that changed with the tides and could take me to any location of the bay with barely a glance at his depth sounder. GPS had not yet been invented, and if it had, he wouldn't have needed it. Ray taught me that a fisherman's livelihood depends on his ability to catch fish, and so, like scientists, fishermen devise, and test, elaborate theories about what structures life in the sea. If they're successful, they catch fish. If they're not, they must refine their theory or come up with a new one.
Ray and I set out in his small cape island fishing boat each morning, just after dawn, to search the bay for krill. We were accompanied by a flotilla of fishing boats, their skippers all convinced that early morning was the best time to catch fish. On our way out to sea we passed a different flotilla coming in from a night of fishing, their skippers equally convinced that night was the best time to catch fish. Fishermen, like scientists, interpret the results of their investigations in many ways and modify their sampling strategies accordingly.
Ray was always happy to put his theories to the test. I asked his advice on the currents that swirled around the ledges where the krill regularly appeared, and he was sure he knew where the currents came from and where they flowed to. We would conduct experiments, throwing drifters into the water to track the current flow. Sometimes they ended up exactly where Ray predicted, sometimes not. "There's another theory shot to hell!" he would mutter from behind his corn-cob pipe when his predictions failed to pass muster.
Fast-forward fifteen years, and I was at the negotiating table as a member of the Australian delegation to the international commission that regulates the fishery for Antarctic krill in the Southern Ocean, where I was proposing the establishment of limits on the catch of krill off a vast area of East Antarctica. The catch limits we had calculated were based on research I had initiated involving a lengthy seventy-two-day survey on the Aurora Australis, a ninety-five-meter (104yard) Australian icebreaker. We had conducted the firstever census of the krill population specifically designed to regulate the fishery. Our team of forty-two scientists and twenty-five crew used state-of-the art electronics, sampling gear, and advanced computing to estimate the size of the krill population. Although this was a dramatic change in scale from my previous sampling activities in Ray Thurber's small green boat, the motivation behind my multi-million-dollar research project was the same — to understand how krill live in their environment so that we could ensure their conservation. The scale and complexity of the operation had changed and so had the species of krill we were studying. This time it was Antarctic krill, the superb krill.
* * *
What are krill? Ask the average person on the street to describe a krill, and the most frequent response is a blank look. On rare occasions the response is "krill are the tiny shrimp-like crustaceans that whales feed on." Many imagine that krill are microscopic, like water fleas or phytoplankton. Few appreciate their real size, which is far from microscopic. If all the animal inhabitants of the ocean from the largest whale to the most minuscule invertebrate are lined up based on size or weight, krill fall in the middle of the pack. Next to their seafaring brethren, they are average in size — not large but not microscopic. Not even tiny.
Antarctic krill, one of eighty-five krill species, were first noticed by whalers in the Southern Ocean. The bellies of the giant whales they hunted were filled almost exclusively with what whalers variously described as shrimps, squillae, animalcules, and insects. Krill had identity issues from the start. Whalers had known of the existence of krill from their observations in the North Atlantic, where several species are abundant and were frequently sighted on the feeding grounds of the great whales.
The word krill is understood to mean "young fish" in Norwegian, but I was informed by a Norwegian colleague that the term is actually an onomatopoeia, a word formed to replicate the sound of millions of krill pattering on the water as they jumped clear of the surface — behavior I had witnessed firsthand in the Bay of Fundy. This surface swarming behavior, exhibited by many species of krill, was another indication of their existence. Since krill are generally only found deep in offshore waters, they are usually seen only by fishermen and whalers and others who venture far from land.
Krill go by many names in the languages of maritime nations. Gaelic fishermen knew them as suil dhu, which means "black eyes." In Japan they are known as esada or okiami, and fishermen in the English-speaking world often refer to them as red bait. But most people have no need of a word for animals they never see and rarely hear of.
In the language of science, however, krill belong to the taxonomic order of Euphausiids, and several of their eighty-five species are abundant in oceanic and some coastal areas around the world. Not surprisingly, Antarctic krill, first scientifically described in 1855, are found in the waters around the frozen continent. It is, without doubt, the most abundant, ecologically and economically important, and best-studied Euphausiid species, and consequently is the focus of this book. From here on, I will use the term krill to refer to Antarctic krill. If I am dealing with other species, such as my first scientific subject, North Atlantic krill (Meganyctiphanes norvegica), I will clearly indicate it. Like sheep, or fish, the name is both singular and plural, so I will use them when referring to the species as a whole, and it when referring to an individual.
Krill are mostly transparent, when alive, with splashes of contrasting red and green, large spherical black eyes, and an elongated, streamlined shape that tapers to a pointed feathery tail. The green comes from the algae they eat and the red from special pigmentation spots that can expand and contract, making their shells a lighter or darker shade of red. When viewed en masse krill can turn the ocean blood-red.
All species of krill also have electric-blue light-emitting organs that dot the body, providing a spectacular light show, particularly when freshly collected. The overall effect is startling, and those who see living krill for the first time are often struck by their translucent beauty. When viewed closely, they are undoubtedly crustaceans, distant cousins to the prawns and shrimps that are so familiar in the displays in fish markets.
The Australian Antarctic Division in Tasmania established a research aquarium especially for the study of Antarctic krill. The aquarium quickly became a favorite of tour groups who grew to appreciate the beauty of free-swimming krill, including visitors as diverse as schoolchildren, politicians, and wildlife celebrities, such as David Attenborough and Jacques Cousteau. This was often the first time they had seen living krill. Inevitably, comments began with, "I didn't realize they were so big!" This has led to my lifetime quest: to quash the misconception that krill are microscopic organisms. Adult Antarctic krill can reach a length of over six centimeters (roughly two and a half inches) and can weigh up to two grams (0,07 ounces).
(Continues…)
Excerpted from "The Curious Life of Krill"
by .
Copyright © 2018 Stephen Nicol.
Excerpted by permission of ISLAND PRESS.
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