| Summary: | Climate change alters species distribution, affecting the organization and functioning of ecosystems. The Barents Sea, a sub arctic shelf sea located to the north of Norway and Russia, has experienced a substantial warming in the last decades, leading to a redistribution of the species that inhabit it. Nektonic species are expected to respond more quickly to climatic changes, causing substantial community rearrangement. Moreover, many of the boreal fish that are experiencing a displacement in the basin are commercially important and thus changes in their distribution should lead to analogous shifts in the fishing effort. This aspect, together with the overall increased human activity in the region, favored by the drastic loss of sea ice cover, could represent an additional stress for the already challenged Arctic ecosystem, highlighting the compelling urge to understand the species distribution dynamics and their main drivers. In this study Species Distribution Models (SDMs) were developed, following a hierarchical procedure, for selected Arctic and boreal nektonic species to investigate the association between climatic changes and the species distribution dynamics, in terms of both biomass and occurrence, in the last decades and the possible correlation of the latter with anthropogenic activity, namely fishing effort and maritime traffic. A time range of seventeen years, from 2004 to 2020, was considered to investigate a potential temporal pattern. Generalized linear models were developed for two Arctic species, Boreogadus saida and Triglops nybelini, and two boreal species, Gadus morhua and Melanogrammus aeglefinus, chosen on the basis of their abundance in the area and functional traits. Nine environmental factors were considered to describe environmental conditions in the basin and their variability through the years. Results showed a strong association between distribution of the species and the environmental drivers, whose spatial dynamic over time seems to be in relation with the spatial-temporal ...
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