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, ^( Y/ I; p: v5 \. z With a body made of calcium carbonate, this sea star lives in the upper reaches of the deep sea’s abyssal plain.
2 L8 f7 Q" j0 j& M8 S* E Where do deep-sea creatures live? Where they won’t dissolve Vast muddy seabeds cover more than 60% of the planet, collectively making them Earth’s largest habitat. At first glance, these frigid, sunless depths all seem more or less the same. Yet the animals that live there, kilometers below the surface, prefer some regions over others, according to a new study. What accounts for their preferences? It’s nothing they can see or sense, the authors say, but an invisible and life-threatening limit imposed by seawater chemistry.This limit demarcates where an important component of many kinds of marine life, calcium carbonate, naturally dissolves. Researchers have long known that microscopic, shelled creatures called forams will vanish under these inhospitable conditions. The new work suggests this restriction on carbonate could also influence where larger animals live. “It’s remarkable,” says Mark Costello, a marine ecologist at Nord University who was not involved with the work, reported today in Nature Ecology & Evolution. “This [limit] will be a major driver of biodiversity in the deep sea everywhere.” It could also drive new discussions surrounding the regulation of deep-sea mining, the authors note, which represents a controversial and looming threat to life on abyssal plains.Almost a decade ago, Erik Simon-Lledó, a marine ecologist with the U.K. National Oceanography Centre, began to study the diversity of life in the Clarion-Clipperton Zone. That’s the part of the abyssal plain in the northeastern Pacific Ocean that extends for about 6 million square kilometers from Mexico to south of Hawaii. Mining companies have explored the region’s seabeds because they contain vast stores of polymetallic nodules, potato-size rocks that are rich in manganese and other valuable metals. Scientists are interested, too, hoping to guide and inform environmental regulations for any future mining—as well as learn about these mysterious ecosystems. One basic question is how—or whether—animals exist in distinct communities, as they do on land. So, Simon-Lledó and colleagues examined images taken by deep-sea robots roaming the zone.The researchers often couldn’t identify species from photographs alone—sometimes characteristic parts of the anatomy, such as on the underside, are not visible from above—so they coded the photographed subjects’ overall shapes into 411 types. Giant sea anemones have long soft tentacles, whereas fan corals stand tall and rigid. Another distinctive creature is a long-armed shrimp that aggressively defends the mounds of sediment it builds for unknown reasons. Pooling their data, the researchers ended up with more than 50,000 creatures of the deep in their data set.When Simon-Lledó plotted the locations of these animals, he found a clear divide in where they preferred to hang out. “It was a bit of a whoa moment,” Simon-Lledó says.The shallower levels of the abyss, between 3800 and 4300 meters, are densely populated with animals that require calcium carbonate for their shells and skeletons, such as shelled mollusks and soft corals, the team found. In deeper water, between 4800 and 5300 meters, soft-bodied animals such as sea cucumbers were much more abundant.The region in between contained a mix of both communities. That crossover occurred at what’s called the carbonate compensation depth (CCD), where the ocean’s pressure, temperature, acidity, and other factors cause calcium carbonate to dissolve. (The exact depth varies across ocean regions.) Organisms living below the CCD must constantly rebuild their shells or carbonate skeletons, or they will dissolve. For some groups, this can be too much to bear.Identifying what lives where in the abyssal plains is important for regulating deep-sea mining, Simon-Lledó says. Researchers worry about the direct impact of removing the nodules, which are essential habitat for corals and other animals that need the hard surface as a place to attach and grow. Also of concern are plumes of sediment whipped up by the mining. This sediment might clog filter-feeding animals, for example. The impacts of mining operations could be more or less severe for various groups depending on where it happens. “The protocol for assessing impact is likely to need to be revised and be different in the shallow and in the deep area,” he says. Marine ecologist Angelika Brandt of the Senckenberg Research Institute agrees: “This is very important to know for conservation.”The study undoubtedly demonstrates that different types of animals are living at different depths in the abyssal plains, says Les Watling, a biological oceanographer at the University of Hawaii at Mānoa, not involved with the work. “Clearly something is determining the depth limits of the species.”But he’s not convinced the CCD is responsible. Watling points out that some groups with bodies containing calcium carbonate, such as sea pens—stinging animals related to coral and jellyfish—were actually more abundant below the CCD than above it, contrary to what researchers would expect. Another possibility, he says, is that the extreme pressure of deeper levels could cause proteins to deform if animals don’t have enough of certain protective molecules called osmolytes.Determining the role of the CCD in bifurcating the communities that call the abyssal plains home will require a more detailed and complete study of the species there, Brandt says.Unfortunately, rising atmospheric carbon dioxide levels could provide a grim natural experiment. As more carbon dioxide enters the ocean from the atmosphere, some scientists predict the CCD depth will rise. If it rises just a few tens of meters within the abyssal plain, the habitable zone for more sensitive species could shrink by thousands of square kilometers. “It would be a major habitat shift, maybe equivalent to sudden expansion of a desert,” Costello says.参考翻译：
4 _1 e9 f2 G% Z 深海生物住在哪里？他们不会消失 广阔的泥质海床覆盖了地球上60%以上的面积，使其成为地球上最大的栖息地。乍一看，这些寒冷、无阳光的深渊似乎都差不多。然而，根据一项新研究，生活在数公里深处的动物更喜欢某些区域。是什么决定了它们的偏好？作者表示，这与它们能看到或感知到的东西无关，而是由海水化学性质所限制的一个无形且危险的界限。这个界限标志着许多种海洋生物重要组成部分之一——碳酸钙自然溶解的位置。研究人员早就知道，在这种恶劣条件下，被称为有孔虫的微小有壳生物将会消失。新研究表明，碳酸盐对于较大动物居住地点也可能产生影响。“这非常引人注目”，今天《自然生态与进化》杂志报道称，“这[界限]将成为深海生物多样性的主要驱动因素。”作者还指出，这可能引发关于深海开采的监管的新讨论，这种开采对深海平原上的生命构成了有争议且逼近的威胁。将近十年前，英国国家海洋学中心的海洋生态学家埃里克·西蒙-勒多开始研究克拉里昂-克利珀顿区生物多样性。该区是太平洋东北部深渊平原的一部分，从墨西哥延伸到夏威夷南部，面积约为600万平方公里。矿业公司已经探索了该地区的海床，因为那里有大量富含锰和其他有价值金属的马铃薯大小的多金属结核。科学家们也很感兴趣，希望能为未来任何开采提供环境监管指导和信息，并了解这些神秘生态系统。一个基本问题是动物是否像陆地上那样存在着不同的群落。因此，西蒙-勒多和同事们研究了在该区域漫游的深海机器人拍摄到的图像。研究人员通常无法仅凭照片就确定物种——有时候从上方看不到特征部位（如下侧）——因此他们将被拍摄对象的整体形状编码为411种类型。巨型海葵有柔软的触手，而扇形珊瑚则高耸而坚硬。另一种独特的生物是一种长臂虾，它会为了未知原因而积极地保护自己建造的沉积物堆。汇总数据后，研究人员得到了超过5万个深海生物的数据集。当西蒙-勒多绘制这些动物的位置时，他发现它们更喜欢待在不同的地方。“这真是令人惊讶”，西蒙-勒多说。团队发现，在3800至4300米之间浅层深渊中，需要碳酸钙来构建壳和骨骼的动物（如有壳软体动物和软珊瑚）数量众多。在4800至5300米之间更深处水域中，软体动物（如海参）更加丰富。两个群落之间区域包含了两者的混合。这种交叉发生在所谓的碳酸盐补偿深度（CCD），在那里，海洋压力、温度、酸度和其他因素导致碳酸钙溶解。（确切的深度在不同海洋地区有所变化。）生活在CCD以下的生物必须不断重建它们的壳或碳酸盐骨骼，否则它们将溶解。对于一些动物群体来说，这可能是无法承受的。西蒙-勒多表示，确定深渊平原上生物栖息地的位置对于监管深海开采至关重要。研究人员担心移除结核会对珊瑚和其他需要坚硬表面作为附着和生长场所的动物造成直接影响。此外，挖掘引起的沉积物悬浮也令人担忧。例如，这些沉积物可能堵塞滤食动物。矿业活动对各个群体的影响可能因发生地点而有所不同。“评估影响的协议可能需要进行修订，并且在浅层和深层区域中会有所不同”，他说。森肯贝格研究所的海洋生态学家安格利卡·布兰特也认同：“这对于保护工作非常重要。”夏威夷大学马诺阿分校的生物海洋学家莱斯·沃特林表示，该研究无疑证明了不同类型的动物生活在深渊平原的不同深度。“显然有某种因素决定了物种的深度限制。”但他并不认为CCD负责这一点。沃特林指出，一些含有碳酸钙体的群体（如海梭菜——与珊瑚和水母相关的刺猬动物）在CCD以下实际上比在CCD以上更丰富，与研究人员预期相反。他说，另一个可能性是更深层次的极端压力会导致蛋白质变形，如果动物没有足够数量的被称为渗透剂的保护分子。布兰特表示，要确定CCD在区分深渊平原上栖息群落中的作用，需要对那里的物种进行更详细、完整的研究。不幸的是，大气二氧化碳水平升高可能提供了一个可怕的自然实验。随着更多二氧化碳从大气进入海洋，一些科学家预测CCD深度将会上升。如果它在深渊平原内仅上升几十米，对于更敏感的物种来说，可居住区域可能会缩小数千平方公里。“这将是一个重大的栖息地转变，也许相当于沙漠的突然扩张”，科斯特洛说。词汇学习： # S; `+ s% Q1 ], S8 e9 r" s
dissolve [dɪˈzɑːlv] (v.) - 溶解 # }% k6 o% A# D7 k M; w
habitat [ˈhæbɪtæt] (n.) - 栖息地
" K7 W; R* z, |8 h2 n% A- G frigid [ˈfrɪdʒɪd] (adj.) - 寒冷的
' U, a. r; w9 x' m depths [dɛpθs] (n.) - 深海
1 G: E8 ?2 b# Y8 u% P0 ]5 ^/ r preferences [ˈprɛfərənsɪz] (n.) - 偏好 1 |4 @) \+ C4 o' N# S# `1 w( V
invisible [ɪnˈvɪzəbəl] (adj.) - 看不见的 6 Y* H5 F9 k5 x, M
demarcates [dɪˈmɑːrkeɪts] (v.) - 划定界限
- I! o% l% U/ P3 ?& a inhospitable [ɪnˈhɑːspɪtəbəl] (adj.) - 不适宜居住的 - T' \- C9 G! D: m
biodiversity [ˌbaɪəʊdɪˈvɜːrsɪti] (n.) - 生物多样性 3 U4 r8 V, ~6 y* o6 m; k
looming [ˈluːmɪŋ] (adj.) - 隐约出现的
, o# h5 y; o; B' a8 k# a distinct [dɪˈstɪŋkt] (adj.) - 不同的
4 p' C; N" M2 G# }# h% A anatomy [əˈnætəmi] (n.) - 解剖学 0 E9 z0 U+ f" }: C& i1 ^( m" n: Y
abyssal [əˈbɪsəl] (adj.) - 深渊的 3 ?0 G* q. A0 J$ O- m; {' N) K
carbonate [ˈkɑːrbənət] (n.) - 碳酸盐 5 n x+ Z9 t* l% h% T1 b, k* M
dissolves [dɪˈzɑːlvz] (v.) - 溶解
6 r; h' v/ D+ o4 J' ?8 n regulate [ˈrɛɡjʊleɪt] (v.) - 管理
: H1 k' g4 }- [8 v9 X$ T9 d% } nodules [ˈnɑːdjuːlz] (n.) - 结节
" L! ]; X+ l& F' ~! z4 Y, _' Y% E: w impact [ˈɪmpækt] (n.) - 影响 8 ^& [4 E1 J+ K( \1 L/ S5 X! E2 D
clog [klɒɡ] (v.) - 堵塞 ! M$ x7 |2 h2 I$ D- r& s5 O
conservation [ˌkɒnsərˈveɪʃən] (n.) - 保护
6 o% m1 p; Q# h" M% a9 I3 x( f8 U bifurcating [baɪˈfɜːrkeɪtɪŋ] (v.) - 分叉
! M* K7 B9 ]. d! b0 i2 X atmospheric [ˌætməsˈfɪrɪk] (adj.) - 大气的 0 |' h1 b* [ g2 y! D
carbon dioxide [ˈkɑːrbən daɪˈɒksaɪd] (n.) - 二氧化碳 ( O% j) Z. o& p. D7 ^8 Y
grim [ɡrɪm] (adj.) - 严酷的
" M, M- Q( K# G8 n6 t* ` shrink [ʃrɪŋk] (v.) - 收缩 + o3 C; g" b; | J2 Q: C
habitat shift [ˈhæbɪtæt ʃɪft] - 栖息地转移
r3 g- l# Y# Z% h 文章大意： 本文主要介绍了深海生物居住的地点与其所需的环境条件。研究发现，海水化学特性中的一种无形且危险的限制，即钙碳酸盐的溶解，影响着深海生物的分布。浅层深海适宜钙碳酸盐壳体的动物生存，而较深的区域则更适合软体动物。这种限制被称为碳酸盐补偿深度（CCD），在调控深海矿产开采和保护生物多样性方面具有重要意义。研究还发现，气候变化导致的二氧化碳增加可能导致CCD上升，进而对深海生物的分布和生态系统造成重大影响。这些发现对于深海研究和保护具有重要价值。
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文章节选自《Science》 $ t7 W% j/ e: g( M" o/ z) b
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