Data_Sheet_4_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已成为一项紧迫的任务。本研究采用生物特性分析评估生态系统功能，并测试深海生物群落中普遍的范式是否适用于北极楚科奇边界陆架（CBL）的底栖表生生物。此外，我们还探讨了环境因素对底栖表生生物功能结构的影响。分析对象为从486至2610米深度使用拖网和遥控潜水器收集的106个物种。最常见的特性模式为小型至中型体型、移动性、底栖直接发育和卵黄囊幼虫发育、捕食性摄食，这些特征在很大程度上支持了全球深海中表生生物的现有观点。底栖表生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，深度和沉积物碳含量解释了大部分功能变异性。自由生活、游泳、悬浮摄食者、机会主义者/食腐者、内受精和球状体的比例丰度在深水站更高。与中水层站相比，深水站的功能冗余（FR）也更高，这表明生物群落通过较少且共享的特性对更为均质化的深海环境进行了适应。中水层站在特性模式组成和功能多样性方面表现出更高的功能变异性，这表明在更为异质化的生境中资源利用更为多样。食物输入与管居、固着、沉积摄食的比例丰度呈正相关。有落石的地区与附着、直立和捕食者的比例丰度较高相关。相对较低的功能冗余可能使CBL中异质化的中水层区域易受干扰，因为其功能丧失的风险。在整个研究区域内，成体和幼虫阶段中具有低扩散能力的物种高发率可能阻碍了生物对变化的快速适应，降低了重新定居和逃避干扰的能力。