Data_Sheet_3_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.

鉴于持续的海冰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的任务。本研究采用生物特性分析来评估生态系统功能，并检验深海生物的常见范式是否适用于深海北极楚科奇边疆（CBL）的底栖表生生物。同时，我们还探讨了环境因素对表生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，这些类群是通过拖网和遥控潜水器收集的。最常见的特性模式为小型至中型体型、移动性、底栖直接和卵黄囊发育的幼虫，以及捕食性摄食，这些特性大多支持了全球深海表生生物的当前观点。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，深度和沉积碳含量解释了大部分的功能变异性。自由生活、游泳、悬浮摄食者、机会主义者/食腐者、内部受精和球形特性的相对丰度在深水站更高。与中水层站相比，深水站的功能冗余（FR）也更高，这表明生物群通过较少且共享的特性适应了更加同质化的深海环境。中水层站在特性模式组成和功能多样性方面均表现出更高的功能变异性，这表明在更加异质化的栖息地中有更多样化的资源利用。食物输入与管居、固着、沉积摄食特性的相对丰度呈正相关。与掉石区域相关联的是附着、直立和捕食者特性的相对丰度更高。相对较低的功能冗余可能使CBL的中水层异质区域容易受到干扰，因为功能丧失的风险。在整个研究区域内，成体和幼虫阶段之间具有低扩散能力的类群高发生率可能阻碍了快速适应变化，降低了重新定居和逃避干扰的能力。