Beschreibung: Arctic oceans are undergoing major changes in many of its fundamental physical constituents, such as shifts from multi- to first-year ice and alterations in the distribution of water masses (Fig. 1). Such changes, often resulting from anthropogenic stressors, have profound impacts on the chemical and biological processes that are at the root of Arctic marine food webs, influencing their structure, function and biodiversity1,2. Yet, much research addressing these on-going changes in the Arctic are limited to local scales or rather exploratory by nature, making it imperative to better characterise and understand the structural and functional diversity of ecological systems that contribute to the marine Arctic across larger scales3,4. We aim to offer more insight in the distributions and abundance of macrobenthic species in Arctic seascapes, e.g. bivalves, polychaetes, and crustaceans that live in marine soft bottoms. Building on recent pan-Arctic community data from 5000 locations, we address a fundamental challenge in Arctic ecological research by employing quantitative models thus far not feasible, enabling assessing spatial diversity patterns and link community organisation and ecosystem functioning.

Beschreibung: We conduct the first model-based assessment of the biogeographical subdivision of Eurasian Arctic seas to (1) delineate spatial distribution and boundaries of macrobenthic communities on a seascape level; (2) assess the significance of environmental drivers of macrobenthic community structures; (3) compare our modelling results to historical biogeographical classifications; and (4) couple the model to climate scenarios of environmental changes to project potential shifts in the distribution and composition of macrobenthic communities by 2100. Location Eurasian Arctic seas, in particular Barents, Kara and Laptev Seas. Taxon 169 species of macrobenthic fauna; most common taxa are Polychaeta (85 species), Malacostraca (30 species), Bivalvia (26 species) and Gastropoda (10 species). Methods We employed the Region of Common Profile (RCP) approach to assess the bioregionalization patterns of Eurasian Arctic seafloor communities. The RCP approach allows the identification of seascape-scale distribution patterns by simultaneously considering biotic and environmental data within one modelling step. Results Four RCPs were identified within the Eurasian Arctic. The results showed that water depth, sea-ice cover, bottom-water temperature and salinity, proportion of fine sediments, particulate organic carbon (POC) and depth of the euphotic zone were among the most important driving variables of macrobenthos communities. The projections, driven by the climate-change scenarios, suggested a general north-eastward shift of the RCPs over the 21st century, mainly correlated with retreating sea-ice and increasing sea-bottom temperature. Main conclusions The identified RCPs largely match the previously reported large-scale distribution patterns of macrobenthic communities in Eurasian Arctic seas. The spatio-temporal dynamics of RCPs are in agreement with local long-term observation data on macrobenthic resilience/vulnerability in the studied region. The representation of the ecoregions and biotas in a probabilistic form, together with quantitative assessment of potential climate-driven changes, will help to adequately consider macrobenthic biodiversity dynamics in the development of science-based conservation measures.