Karsenti\u2019s revelation meant he had to go where most of the world\u2019s plankton live\u2014to the ocean. Which meant he had to find a boat. And that led him to the schooner Tara<\/em>, and a journey around the world that would involve 150 scientists.<\/p>\n The schooner, Tara<\/em>, on its journey around the world to study marine plankton. Photo by F. Latreille\/Tara Expedition<\/p><\/div>\n Karsenti has always been a keen sailor and, like so many scientists over the ages, his imagination has been fired by the romantic seafaring quests of western scientists, including the 1,000-day expedition in the 1870s of the HMS Challenger<\/em> that set the tone for modern marine biology, discovering new species and sounding the ocean\u2019s mysterious depths; and Charles Darwin\u2019s 1830s round-the-world voyage of nearly five years on HMS Beagle<\/em>, that led him to find exotic new creatures and eventually develop his theory of evolution.<\/p>\n About 10 years ago, Karsenti enlisted the intellectual help of cell biologist Christian Sardet and plankton specialist Gaby Gorsky, both of the Observatoire Oc\u00e9anologique de Villefranche-sur-Mer, on the Mediterranean Coast of France. Together they came up with an idea and a bold 21st-century plan: a modern-day expedition that was Darwinian and necessary to unravel the story of plankton.<\/p>\n \u201cThere was a feeling that what was needed was to study plankton end to end, viruses to small organisms,\u201d Karsenti says. \u201cThere was a hole there. Somehow, nobody had done it \u2026 It was a discovery of part of the universe you don\u2019t know.\u201d<\/p>\n But, embedded within Karsenti\u2019s new plan to study plankton holistically, was a possibility yet more urgent: could the fate of plankton be linked to the fate of other species, including humans?<\/p>\n The idea that marine planktonic organisms are a linchpin to the planet\u2019s fundamental operation is recent. To Darwin, who captured plankton in a net he pulled behind the Beagle<\/em>, they were, at best, a scientific curiosity. He wrote on January 11, 1832: \u201cMany of these creatures so low in the scale of nature are most exquisite in their forms & rich colours. It creates a feeling of wonder that so much beauty should be apparently created for such little purpose.\u201d<\/p>\n Nearly a century later, Winfred Emory Allen, a plankton specialist at Scripps Institute of Oceanography at University of California, San Diego, had turned that view on its head, writing in 1927 that \u201cevery plankton organism is important,\u201d if only because it is food for something else. He pleaded for scientists to study planktonic life.<\/p>\n The Sir Alister Hardy Foundation for Ocean Science in Plymouth, England took up the call in 1931, and has been collecting plankton samples ever since by providing fine silk nets for merchant and research ships to drag through the North Atlantic and North Sea. The goal was to use plankton samples as a measure to predict the health of the commercial fisheries in those parts of the ocean.<\/p>\n More recently, as computing power advanced enough to analyze massive volumes of data, the adventurer and geneticist J. Craig Venter traveled around the globe in his yacht Sorcerer II<\/em>, which he called a \u201cfloating lab,\u201d snatching up bacterial plankton and then chopping them randomly into bits to examine their genomic sequences, reporting in 2007 the discovery of 1.2 million new genes.<\/p>\n By the time Karsenti and the expedition crew was setting off in Tara<\/em>, the 36-meter sailing ship provided by Etienne Bourgois, son of the French fashion designer agn\u00e8s b., pieces of the planktonic puzzle were steadily falling into place. The expedition could pose even more pressing questions\u2014more \u201chows\u201d and \u201cwhys\u201d\u2014than they had originally set.<\/p>\n Expedition leaders, Eric Karsenti (left) and Tara<\/em> owner Etienne Bourgois, son of the French fashion designer agn\u00e8s b., in Patagonia. Photo by Patrick Filleux\/AFP\/Getty Images<\/p><\/div>\n Not only that, but the Tara Expedition also coincided with an emerging trend: ocean scientists were beginning to look at the ocean as a whole system and to see how it connects with other systems on the planet. While much of the long history of biology has been aimed at collecting, cataloguing, and naming organisms, the study of ecology\u2014a discipline that examines how organisms interact with one another and their environment\u2014rose to prominence in the latter half of the 20th century. Rachel Carson\u2019s 1962 book Silent Spring<\/em>, is an early example of the discipline.<\/p>\n Until very recently, ecological studies focused primarily on terrestrial, rather than marine, environments. The first major scientific papers on ocean acidification came out in 1999 and 2000. The first paper describing a global map of human effects on marine ecosystems was published in 2008. Other research looking at whole ocean systems\u2014say, its nitrogen content or how oxygen gets moved around\u2014is even more recent.<\/p>\n As Tara<\/em> set off, the emerging picture was this: plankton as a connected global community rather than a sea of isolated individuals; and plankton as global workhorses, engineers of the atmosphere and climate. And it was all happening in the ocean, a watery medium that scientists were just starting to see as a global force in itself.<\/p>\n Perhaps more importantly, marine researchers were beginning to realize that the chemistry of the ocean is changing fast\u2014\u201cat a rate we almost can\u2019t comprehend,\u201d says Philip Boyd, an ocean biogeochemist at the Institute for Marine and Antarctic Studies in Hobart, Tasmania.<\/p>\n The cause: mounting carbon dioxide concentrations in the atmosphere that get soaked up into the ocean. Plankton\u2014an understudied critical cog in the atmospheric engine\u2014were suddenly at risk.<\/p>\n The changes plankton now face are fundamental ones: the ocean is becoming warmer and more acidic, and their access to nutrients, oxygen, trace metals, and light is shifting.<\/p>\n Each of these affects the growth and survival of different plankton in different ways. For example, as the water becomes more acidic, plankton and other creatures that make shells and other structures out of calcium carbonate have a harder time with their construction, a phenomenon that is becoming better known. Less well known is that large sections of the deep ocean far from the coastlines are becoming anoxic, making them inhospitable to most life.<\/p>\n![](\"\/wp-content\/uploads\/tara-story-plankton.jpg\")
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