Team Players


By Jeffrey Marlow /Rogier Braakman J. マーロウ /R. ブラークマン
English 日本語 日本語
Half a mile below the surface of the ocean, off the coast of Oregon, the Alvin submersible’s headlights flicker on to reveal a colorful oasis. Plush carpets of white, yellow and orange microbes cover the seafloor, punctuated by fields of clams and mussels. Red rockfish watch the vessel warily with bulbous milky eyes, while bubble plumes belch from mounds of chalky, variegated rock. The halo of illumination draws visitors forward like a lure, exposing this alien terrain bit by unexpected bit while obscuring its true extent.  オレゴン州沖の水深800mの海の中,潜水艇アルビン号のヘッドライトが点灯すると,色鮮やかなオアシスが目の前に広がった。白や黄色,オレンジのビロードのような微生物のカーペットに覆われた海底のところどころに二枚貝が群生している。赤いカサゴの仲間がまん丸い乳白色の目で潜水艇を用心深く見つめ,灰白色の岩の小山から泡が噴き出して立ち上っている。ヘッドライトの明かりがルアーのように訪問者を船首に引き寄せ,この異質なエリアの予想外の姿を少しずつ明らかにする一方で,その真の広がりは依然として闇に包まれたままだ。
Hours earlier on this expedition in 2010, one of us (Marlow) had wriggled his way into Alvin’ s titanium sphere, along with two other explorers. We pressed our faces to the circular windows as we descended through a kaleidoscope of blue. Our destination was Hydrate Ridge, a rocky precinct where vast quantities of methane are being squeezed out of Earth’s crust. With the accelerating pace of discovery of such methane seeps, as they are known (450 were found during a single 2016 expedition in the eastern Pacific), scientists are racing to understand their environmental impact. Methane, after all, is a strong greenhouse gas: although it constitutes only 0.00018 percent of the atmosphere, it accounts for 20 percent of the atmosphere’s overall warming potential. Estimates suggest that roughly 10 percent of atmospheric methane emerges from seafloor seeps every year. Unchecked, this bubble stream could wreak climate havoc, but something prevents more methane from reaching the atmosphere: the microbes living in the seeps.  2010年に行われたこの海底探査の数時間前,著者の1人(マーロウ)は2人の探検家とともにアルビン号のチタン製の球体の中に身をよじらせて乗り込んだ。千変万化する青い海の中を下降する間,私たちは丸窓に顔を押し付けて外を覗いていた。目的地はハイドレート・リッジと呼ばれる,地殻からメタンが大量に絞り出されている岩だらけの区域だった。
These microbes, which dwell underneath the white microbial mats and clam shards, consume methane with remarkable voracity. Individually minuscule but collectively mighty, they work together in ways that help to shape landscapes, sustain ecosystems and impact the planet’s climate. Their power lies in their cooperation. Scientists have known about these microorganisms for decades, yet they remain mysterious in many respects. Key among the unknowns is the extent of their influence: Do they reside in only a few regions of the ocean floor, or are they widespread? More broadly, is their propensity for cooperation exceptional among microbes, or is it commonplace? Prevailing views long held that such organisms mostly compete with one another for resources. But maybe teamwork is actually their default mode. We were there—a speck of light suspended in the inky expanse—to figure out just how pervasive this way of life really is.  これらの微生物は白い微生物マットや二枚貝の破片の下に生息し,驚くほど貪欲にメタンを消費している。個々の微生物は極めて小さいが,まとまると大きな力を発揮する。彼らは協力して景観を作り出し,生態系を支え,地球の気候に影響を及ぼしている。そのパワーの源泉は協力だ。
 協力し合う微生物の存在は何十年も前から知られていたが,依然として多くの点で謎めいている。わかっていないことのうちで特に重要なのは,その影響の程度だ。彼らは海底の限られた領域にだけ生息しているのか,それとも広範囲に存在しているのか? さらに,彼らが協力し合う傾向は微生物の世界では特別なのか,あるいはよく見られるものなのか?