Abstract：
As anthropogenic disturbance on deep-sea seamount ecosystems grows, there is an urgent need for a better understanding of the biodiversity and community structure in benthic ecosystems, which can vary at local and regional scales. A survey of the benthic megafauna on two adjacent deep-water seamounts in the northwestern Pacific Ocean was conducted, which are covered by cobalt-rich crusts, to assess the biodiversity patterns and dissimilarity of assemblage composition. Based on a multidisciplinary dataset generated from video recordings, multibeam bathymetry data, and near-bottom currents, environmental and spatial factors impacting the megabenthic communities were explored. Results showed that these two deep-water seamounts were dominated by hexactinellids, crinoids, and octocorals. The seamounts were able to support diverse and moderately abundant megafauna, with a total of 6436 individuals classified into 94 morphospecies. The survey covered a distance of 52.2 km across a depth range of 1421-3335 m, revealing multiple distinct megabenthic assemblages. The megabenthic communities of the two deep-water seamounts, with comparable environmental conditions, exhibited similarities in overall density, richness, and faunal lists, while dissimilarities in the relative abundance of taxa and assemblage composition. No gradual depth-related change in terms of abundance, richness, or species turnover was observed across the two seamounts, despite the statistical significance of depth in structuring the overall communities. The spatial distribution of megabenthic communities displayed a discontinuous and patchy pattern throughout the two deep-water seamounts. This patchiness was driven by the interactive effects of multiple environmental factors. Near-bottom currents and microhabitat features were the primary drivers influencing their dissimilarities in megabenthic community structure. This case study on the megabenthic community structure of two adjacent seamounts with cobalt-rich crusts can serve as an environmental baseline, providing a reference status for the conservation and management of seamount ecosystems, particularly valuable for areas being considered for deep-sea mining.
摘要：
随着深海海山生态系统人为干扰的增长，迫切需要更好地了解底栖生态系统的生物多样性和群落结构，这可能在当地和区域范围内有所不同。对西北太平洋两处相邻深水海山的底栖大型动物进行了调查,被富钴结壳覆盖，评估生物多样性模式和组合组成的差异。基于从视频记录中生成的多学科数据集，多波束测深数据,和接近底部的电流，探讨了影响巨型底栖群落的环境和空间因素。结果表明，这两个深水海山以六叶草为主，海百合,和八珊瑚。海山能够支撑适度丰富和多样化的大型动物，共有6436个个体分为94种形态物种。调查涵盖了52.2公里的距离，深度范围为1421-3335米，揭示出多个不同的巨石组合。两个深水海山的大型群落，在可比的环境条件下，在总体密度上表现出相似性，丰富,和动物群名单，而分类群和组合组成的相对丰度不同。在丰度方面没有逐渐的深度相关变化，丰富,或者在两个海底山观察到物种周转，尽管深度在构建整体社区方面具有统计意义。在整个两个深水海山中，大型底栖群落的空间分布表现出不连续和斑驳的格局。这种斑块是由多种环境因素的相互作用驱动的。近底洋流和微生境特征是影响它们在巨型底栖群落结构中的差异的主要驱动因素。本案例研究了两个相邻的具有富钴结壳的海山的大型底栖群落结构，可以作为环境基线，为海山生态系统的保护和管理提供参考，对于正在考虑进行深海采矿的地区特别有价值。
