Data_Sheet_5_Functional Pattern of Benthic Epifauna in the Chukchi Borderland, Arctic Deep Sea.CSV

Assessment of Arctic deep-sea ecosystem functioning is currently an urgent task considering that ongoing sea-ice reduction opens opportunities for resource exploitation of yet understudied deep-sea regions. We used Biological Trait Analysis to evaluate ecosystem functioning and test if common paradigms for deep-sea fauna apply to benthic epifauna of the deep-sea Arctic Chukchi Borderland (CBL). We also investigated the influence of environmental factors on the functional structure of the epifauna. The analysis was performed for 106 taxa collected with a beam trawl and a Remotely Operated Vehicle from 486 to 2610 m depth. The most common trait modalities were small-medium size, mobile, benthic direct and lecithotrophic larval development, and predatory feeding, which mostly supports the current view of epifauna in the global deep sea. Functional composition of epifauna differed between two depth strata (486–1059 m and 1882–2610 m), with depth and sediment carbon content explaining most of the functional variability. Proportional abundances of the modalities free-living, swimming, suspension feeders, opportunists/scavengers, internal fertilization and globulose were higher at deep stations. Functional redundancy (FR) was also higher there compared to the mid-depth stations, suggesting adaptation of fauna to the more homogeneous deep environment by fewer and shared traits. Mid-depth stations represented higher functional variability in terms of both trait modality composition and functional diversity, indicating more variable resource use in the more heterogeneous habitat. Food input correlated positively with the proportional abundance of the modalities tube-dwelling, sessile and deposit feeding. Areas with drop stones were associated with higher proportional abundance of the modalities attached, upright, and predators. Comparatively low FR may render the heterogeneous mid-depth area of the CBL vulnerable to disturbance through the risk of loss of functions. Across the study area, high occurrence of taxa with low dispersal ability among adult and larval life stages may prevent rapid adaptation to changes, reduce ability to recolonize and escape perturbation.

鉴于持续的海洋冰层减少为尚未充分研究的深海区域资源开发提供了机遇，对北极深海生态系统功能的评估目前已成为一项迫切任务。本研究采用生物特征分析，评估生态系统功能，并检验深海生物普遍范式是否适用于深海北极楚科奇边界的底栖附着生物。此外，我们还研究了环境因素对底栖附着生物功能结构的影响。分析针对从486至2610米深度采集的106个类群进行，这些类群系通过拖网和遥控无人航行器收集。最常见的特征模式为中小型、移动性、底栖直接和卵黄囊幼虫发育，以及捕食性摄食，这些特征大多支持了关于全球深海底栖附着生物的现行观点。底栖附着生物的功能组成在两个深度层（486–1059米和1882–2610米）之间存在差异，深度和沉积碳含量解释了大部分的功能变化。在深水站，自由生活、游泳、悬浮摄食者、机会主义者/食腐者、体内受精和球状类群的相对丰度较高。与中深度站相比，深水站的功能冗余（FR）也较高，这表明生物群落通过较少的共享特征适应了更为均质化的深海环境。中深度站代表了在特征模式组成和功能多样性方面的更高功能变异性，这表明在更为异质化的栖息地中有更丰富的资源利用。食物输入与管状栖息、附着和沉积摄食类群的相对丰度呈正相关。具有落石区域与附着、直立和捕食者的相对丰度较高相关。相对较低的功能冗余可能导致CBL的中层深度区域因功能丧失的风险而容易受到干扰。在整个研究区域内，成体和幼虫阶段中具有低扩散能力的类群高频率出现，可能阻碍了快速适应变化、降低复育能力和逃避干扰的能力。