Data_Sheet_6_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缩减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。本研究采用生物特征分析手段，评估生态系统功能，并检验深海生物普遍范式是否适用于北极楚科奇边界陆架（CBL）的底栖附着生物。同时，我们还探讨了环境因素对附着生物功能结构的影响。分析对象为从486至2610米深度范围内，使用拖网和遥控潜水器采集的106种生物。最常见的特征模式为小型至中型体型、移动性、底栖直接发育和卵黄囊营养幼虫发育，以及捕食性摄食，这些特征在很大程度上支持了全球深海附着生物的现有观点。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异性。自由生活、游泳、悬浮摄食、机会主义者/食腐者、内部受精和球形特征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，这表明生物群通过较少的共享特征来适应更均匀的深海环境。中水层站的功能变异性在特征模式组成和功能多样性方面均较高，表明在更为异质化的生境中资源利用的多样性更大。食物输入与管居、固着、沉积摄食特征的比例丰度呈正相关。有落石的区域与附着、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的中水层异质区域易受干扰，风险在于功能丧失。在整个研究区域内，成体和幼虫生命周期中具有低扩散能力的生物种类的普遍存在可能阻碍对变化的快速适应，降低重新定居和逃避干扰的能力。