Description: A photographic seabed survey conducted off the Antarctic Peninsula region provided the opportunity to study spatial patterns, abundance and behaviour of the notothenioid benthic fish fauna. Overall, a total of 12,715 images taken with the Ocean Floor Observation System (OFOS) along 26 transects in three ecoregions (Joinville Island, Bransfield Strait and Drake Passage) were analysed. The fish fauna consisted of at least 34 species belonging to four families of both low-Antarctic and high-Antarctic origin. Nototheniids showed the highest relative abundance and species richness, followed by channichthyids, bathydraconids and artedidraconids. Direct in-situ observations in OFOS seabed images allowed descriptions of fish behaviour, such as aggregation of individuals (Notothenia coriiceps), specific body postures (Cygnodraco mawsoni and Cryodraco antarcticus) and parental care (Chaenodraco wilsoni, Chionodraco rastrospinosus, Pagetopsis macropterus and Trematomus hansoni). Fish density and species richness was primarily correlated with the occurrence of bryozoans, ascidians, and large cup-shaped sponges, providing a three-dimensional habitat suitable for fish settling, foraging, breeding and refuge from predators. Fish diversity was higher (a) off Joinville Island and in Bransfield Strait than in Drake Passage, where almost exclusively low-Antarctic species were recorded, and (b) between 100 and 600 m than at greater depths. Overall, the benthic fish fauna off the northern Antarctic Peninsula is zoogeographically composite and widespread, with well-structured spatial partitioning.

Description: 〈jats:title〉Abstract〈/jats:title〉〈jats:p〉In times of accelerating climate change, species are challenged to respond to rapidly shifting environmental settings. Yet, faunal distribution and composition are still scarcely known for remote and little explored seas, where observations are limited in number and mostly refer to local scales. Here, we present the first comprehensive study on Eurasian-Arctic macrobenthos that aims to unravel the relative influence of distinct spatial scales and environmental factors in determining their large-scale distribution and composition patterns. To consider the spatial structure of benthic distribution patterns in response to environmental forcing, we applied Moran’s eigenvector mapping (MEM) on a large dataset of 341 samples from the Barents, Kara and Laptev Seas taken between 1991 and 2014, with a total of 403 macrobenthic taxa (species or genera) that were present in ≥ 10 samples. MEM analysis revealed three spatial scales describing patterns within or beyond single seas (broad: ≥ 400 km, meso: 100–400 km, and small: ≤ 100 km). Each scale is associated with a characteristic benthic fauna and environmental drivers (broad: apparent oxygen utilization and phosphate, meso: distance-to-shoreline and temperature, small: organic carbon flux and distance-to-shoreline). Our results suggest that different environmental factors determine the variation of Eurasian-Arctic benthic community composition within the spatial scales considered and highlight the importance of considering the diverse spatial structure of species communities in marine ecosystems. This multiple-scale approach facilitates an enhanced understanding of the impact of climate-driven environmental changes that is necessary for developing appropriate management strategies for the conservation and sustainable utilization of Arctic marine systems.〈/jats:p〉

Description: 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.