The deep sea, Earth’s largest biome, harbors numerous unknown species. Prior to the AleutBio (Aleutian Trench Biodiversity Studies) expedition from July to September 2022, the Northeast (NE) Pacific at abyssal and hadal depths was virtually unexplored. Our study presents new findings from the AleutBio project on the macrofaunal composition of the Bering Sea (BS) and Aleutian Trench (AT) collected by means of an epibenthic sledge (EBS), comparing these results with data from the Kuril-Kamchatka Trench (KKT) and the Northwest (NW) Pacific. Additionally, we examine variations in macrofaunal composition and abundance across different regions and depths. A biogeographic gap analysis using data from the Ocean Biodiversity Information System (OBIS) and the Global Biodiversity Information Facility (GBIF) found that, out of 170,627 occurrence records from the North Pacific and Bering Sea, only 153 were from depths below 3,500 m. The AleutBio project addressed this gap by significantly expanding the dataset with 36,499 new records collected during the expedition using an EBS. Nearly 98% of the specimens were from five phyla: Arthropoda, Annelida, Mollusca, Echinodermata, and Nematoda, with Polychaeta, Copepoda, and Nematoda being the most abundant taxa. Although the number of individuals varied between stations, there was no significant decrease in abundance with increasing depth, and some hadal stations had similar numbers of invertebrates as abyssal stations. Regional differences were observed, with Polychaeta and Nematoda being dominant in the BS, and Copepoda more prevalent at western abyssal stations. Depth emerged as the key factor influencing macrofaunal distribution, with distinct patterns across bathyal, abyssal, and hadal depths. Comparisons with other NW Pacific regions, like the Sea of Japan and the Sea of Okhotsk, show that depth and water body isolation play crucial roles in shaping faunal communities. AleutBio’s extensive sampling below 3,500 m has vastly increased available data, aiding in the understanding and conservation of deep-sea biodiversity. While certain taxa showed patchy distributions, no significant differences in faunal composition were found between geographic areas or depth zones. These findings underscore the dynamic nature of deep-sea ecosystems and highlight the importance of depth in shaping macrofaunal communities, emphasizing the need for continued research in these fascinating environments.

中文翻译：

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北太平洋北部深海、深海和深海带的表层和超底栖大型动物群落组成和分布


深海是地球上最大的生物群落，栖息着许多未知物种。在 2022 年 7 月至 9 月的 AleutBio（阿留申海沟生物多样性研究）科考之前，位于深海和海底深度的东北 （NE） 太平洋几乎未被探索。我们的研究提出了 AleutBio 项目关于通过表层底栖雪橇 （EBS） 收集的白令海 （BS） 和阿留申海沟 （AT） 大型动物组成的新发现，并将这些结果与千岛-堪察加海沟 （KKT） 和西北 （NW） 太平洋的数据进行了比较。此外，我们还研究了不同地区和深度的大型动物组成和丰度的变化。使用来自海洋生物多样性信息系统 （OBIS） 和全球生物多样性信息设施 （GBIF） 的数据进行的生物地理差距分析发现，在北太平洋和白令海的 170,627 条出现记录中，只有 153 条来自 3,500 米以下的深度。AleutBio 项目通过显著扩展数据集来填补这一差距，在考察期间使用 EBS 收集了 36499 条新记录。近 98% 的标本来自五个门：节肢动物门、环节动物门、软体动物门、棘皮动物门和线虫门，其中多毛类、桡足纲和线虫门是最丰富的分类群。尽管个体数量因站点而异，但随着深度的增加，丰度没有显著下降，一些 hadal 站点的无脊椎动物数量与深海站点相似。观察到区域差异，多毛类和线虫在 BS 中占主导地位，而桡足类在西部深海站更为普遍。深度成为影响大型动物分布的关键因素，在深海、深海和深海深度具有不同的模式。 与其他西北太平洋地区（如日本海和鄂霍次克海）的比较表明，深度和水体隔离在塑造动物群落方面起着至关重要的作用。AleutBio 在 3,500 米以下的广泛采样大大增加了可用数据，有助于了解和保护深海生物多样性。虽然某些分类群呈斑块状分布，但在地理区域或深度区域之间没有发现动物群组成存在显著差异。这些发现强调了深海生态系统的动态性质，并强调了深度在塑造大型动物群落中的重要性，强调了在这些迷人的环境中继续研究的必要性。