The biogeographic transition from boreal to Arctic marine communities entails a strong taxonomic and functional turnover. Communities living in these areas are being strongly affected by climate warming with rapid reorganizations and change in ecosystem functioning. We assess the megabenthic species composition and functional character in a transition zone around Svalbard. The relationships between environment, taxonomic composition and functional traits are investigated and discussed regarding the potential impacts of climate warming. The biomass data from 293 taxa, coded with 6 functional traits (29 modalities), from 144 trawl stations, were analyzed by multivariate statistics based on taxonomy, RLQ- and fourth corner analysis, based on environment and traits. We find that boundaries between water masses and depths are associated gradual taxonomic and sharp functional transitions. We document a biogeographic transition zone on the slope northeast of Svalbard where surface deposit feeding crustacean associations meet crawling Arctic echinoderm predators. Further we show a sharp transition at 500 m depth along the shelf of Svalbard where boreal filtrating deep-sea sponges meet a unique upraised large-bodied assemblage of bathyal species on the Yermak Plateau. Global warming will likely cause rapid taxonomic and functional shifts in these transition areas, with filtrating sponges and deposit feeding crustaceans possibly expanding into Arctic communities while large, upright, predators further down the slope. There is a need for both monitoring of the transition areas, and for protecting the most vulnerable deep and arctic fauna on the Yermak Plateau.

从北方到北极海洋群落的生物地理过渡需要强大的分类和功能更替。生活在这些地区的社区正受到气候变暖的强烈影响，生态系统功能迅速重组和变化。我们评估了斯瓦尔巴群岛周围过渡区的巨型底栖动物物种组成和功能特征。关于气候变暖的潜在影响，研究和讨论了环境、分类组成和功能特征之间的关系。来自 144 个拖网站的 293 个分类群的生物量数据，编码为 6 个功能性状（29 种模式），通过基于分类学、RLQ 和第四角分析的多元统计分析，基于环境和性状。我们发现水团和深度之间的边界与逐渐的分类和急剧的功能转变有关。我们在斯瓦尔巴群岛东北部的斜坡上记录了一个生物地理过渡区，在那里，以甲壳类动物为食的地表沉积物与爬行的北极棘皮动物捕食者相遇。此外，我们还展示了斯瓦尔巴大陆架沿线 500 m 深度处的急剧过渡，在该处，北方过滤的深海海绵与耶尔马克高原上独特的隆起的大型深海物种组合相遇。全球变暖可能会导致这些过渡地区的快速分类和功能变化，过滤海绵和沉积物喂养甲壳类动物可能会扩展到北极社区，而大型、直立的捕食者会进一步下坡。有必要对过渡区域进行监测，