Abstract
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.
Highlights
Understanding spatial patterns and temporal dynamics of biotic community structure and processes in relation to intrinsic factors and environmental forcing is a longstanding concern in ecology (Legendre 1993)
The reduction of sea ice, which is one of the most obvious effects of warming in polar regions, and the alterations of its dynamics lead to large-scale changes in the environmental conditions of Arctic seas, with cascading impacts on marine ecosystems (Macias-Fauria and Post 2018)
Variation partitioning revealed that both spatial distances among sampling locations and environmental variables considered in our study explained part of the overall variation in the community data, ranging from 17.3% for the ≤ 100-km scale to 23.3% across all spatial scales (Fig. 3)
Summary
Understanding spatial patterns and temporal dynamics of biotic community structure and processes in relation to intrinsic factors and environmental forcing is a longstanding concern in ecology (Legendre 1993). The reduction of sea ice, which is one of the most obvious effects of warming in polar regions, and the alterations of its dynamics lead to large-scale changes in the environmental conditions of Arctic seas, with cascading impacts on marine ecosystems (Macias-Fauria and Post 2018). This includes the composition and spatial distribution of benthic communities (Doney et al 2012), the knowledge of which is of high value for environmental protection efforts (Sirenko 2001). Bathymetry, water temperature, salinity, and sediment properties are considered the environmental drivers that are most influential in determining benthic biodiversity patterns and processes (Vedenin et al 2015), while fisheries, persistent contaminants, industrial development and shipping are key anthropogenic drivers (Yasuhara et al 2012; CAFF 2017)
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