Malviya Shruti, Scalco Eleonora, Audic Stéphane, Vincent Flora, Veluchamy Alaguraj, Poulain Julie, Wincker Patrick, Iudicone Daniele, de Vargas Colomban, Bittner Lucie, Zingone Adriana, Bowler Chris
Institut de Biologie de l'École Normale Supérieure, École Normale Supérieure, Paris Sciences et Lettres Research University, CNRS UMR 8197, INSERM U1024, F-75005 Paris, France;
Stazione Zoologica Anton Dohrn, 80121 Naples, Italy;
Proc Natl Acad Sci U S A. 2016 Mar 15;113(11):E1516-25. doi: 10.1073/pnas.1509523113. Epub 2016 Feb 29.
Diatoms (Bacillariophyta) constitute one of the most diverse and ecologically important groups of phytoplankton. They are considered to be particularly important in nutrient-rich coastal ecosystems and at high latitudes, but considerably less so in the oligotrophic open ocean. The Tara Oceans circumnavigation collected samples from a wide range of oceanic regions using a standardized sampling procedure. Here, a total of ∼12 million diatom V9-18S ribosomal DNA (rDNA) ribotypes, derived from 293 size-fractionated plankton communities collected at 46 sampling sites across the global ocean euphotic zone, have been analyzed to explore diatom global diversity and community composition. We provide a new estimate of diversity of marine planktonic diatoms at 4,748 operational taxonomic units (OTUs). Based on the total assigned ribotypes, Chaetoceros was the most abundant and diverse genus, followed by Fragilariopsis, Thalassiosira, and Corethron We found only a few cosmopolitan ribotypes displaying an even distribution across stations and high abundance, many of which could not be assigned with confidence to any known genus. Three distinct communities from South Pacific, Mediterranean, and Southern Ocean waters were identified that share a substantial percentage of ribotypes within them. Sudden drops in diversity were observed at Cape Agulhas, which separates the Indian and Atlantic Oceans, and across the Drake Passage between the Atlantic and Southern Oceans, indicating the importance of these ocean circulation choke points in constraining diatom distribution and diversity. We also observed high diatom diversity in the open ocean, suggesting that diatoms may be more relevant in these oceanic systems than generally considered.
硅藻（硅藻门）是浮游植物中种类最多、生态意义最重要的类群之一。它们在营养丰富的沿海生态系统和高纬度地区被认为尤为重要，但在贫营养的开阔海洋中重要性则低得多。“塔拉海洋”环球考察使用标准化采样程序从广泛的海洋区域采集了样本。在这里，对来自全球海洋光合层46个采样点收集的293个大小分级浮游生物群落的约1200万个硅藻V9 - 18S核糖体DNA（rDNA）核糖型进行了分析，以探索硅藻的全球多样性和群落组成。我们对海洋浮游硅藻的多样性进行了新的估计，为4748个操作分类单元（OTU）。根据已分类的核糖型总数，角毛藻属是最丰富和多样的属，其次是拟脆杆藻属、海链藻属和心骨藻属。我们仅发现少数几种世界性核糖型在各站点分布均匀且丰度高，其中许多无法可靠地归为任何已知属。确定了来自南太平洋、地中海和南大洋水域的三个不同群落，它们内部有很大比例的核糖型相同。在分隔印度洋和大西洋的厄加勒斯角以及大西洋和南大洋之间的德雷克海峡沿线，观察到多样性突然下降，这表明这些海洋环流瓶颈点在限制硅藻分布和多样性方面的重要性。我们还在开阔海洋中观察到高硅藻多样性，这表明硅藻在这些海洋系统中的相关性可能比通常认为的更高。
