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Aim: In complex networks, the degree distribution varies and provides an insight into the general structure of the system. For example, it may show scale‐free characteristics of the network, indicating higher vulnerability against non‐random disturbances. However, investigating its spatio‐temporal variability, degree distribution in marine food webs remains an unresolved issue. In this paper, we focus on describing the global variability of degree distribution in marine food webs. Location: Global. Methods: We studied 105 marine food webs. By Kolmogorov–Smirnov test, and kernel density estimation, we determined the degree distribution of each food web, described its spatio‐temporal pattern and quantified the correlation between relevant parameters as a function of the scale‐free property of the degree distribution. Results: Marine food webs around the globe did not strictly exhibit scale‐free characteristics in most regions, and only below 5% of the food webs entered the "strongest fit" level of the scale‐free network. We also find food webs in the polar regions indicate relatively high goodness‐of‐fit to scale‐free networks. The upwelling ecosystem related to ocean currents is prone to form a scale‐free web, which exhibits periodic scale‐free characteristics. The ecosystem types with relatively 'low fit' levels were mainly concentrated in the ecosystems heavily influenced by human activities. Main Conclusions: This research will enhance the research in terms of (a) classifying degree distribution in marine food webs; (b) revealing the variability in the spatial pattern of particular distributions, for example, the scale‐free characteristics and (c) exploring the distribution of in‐degree in space, quantifying the proportion of generalist and specialist species, as a potential indicator of adaptive potential of ecosystems. This research contributes to our understanding of the scale‐free features of marine food webs globally. It also offers a real systems‐based conservation approach to assess the spatial heterogeneity of the structural vulnerability of marine ecosystems. [ABSTRACT FROM AUTHOR]

Climate change affects ecosystems at several levels: by altering the spatial distribution of individual species, by locally rewiring interspecific interactions, and by reorganizing trophic networks at larger scales. The dynamics of marine food webs are becoming more and more sensitive to spatial processes and connections in the seascape. As a case study, we study the atlantification of the Barents Sea: we compare spatio-temporal subsystems at three levels: the identity of key organisms, critically important interactions and the entire food web. Network analysis offers quantitative measurements, including centrality indices, trophic similarity indices, a topological measure of interaction asymmetry and network-level measures. We found that atlantification alters the identity of key species (boreal demersals becoming hubs), results in strongly asymmetric interactions (dominated by haddock), changes the dominant regulation regime (from bottom-up to wasp-waist control) and makes the food web less modular. Since the results of food web analysis may be quite sensitive to network construction, the aggregation of food web data was explicitly studied to increase the robustness of food web analysis. We found that an alternative, mathematical aggregation algorithm better preserves some network properties (e.g. density) of the original, unaggregated network than the biologically inspired aggregation into functional groups. This article is part of the theme issue 'Connected interactions: enriching food web research by spatial and social interactions'. [ABSTRACT FROM AUTHOR]

This theme issue features 18 papers exploring ecological interactions, encompassing metabolic, social, and spatial connections alongside traditional trophic networks. This integration enriches food web research, offering insights into ecological dynamics. By examining links across organisms, populations, and ecosystems, a hierarchical approach emerges, connecting horizontal effects within organizational levels vertically across biological organization levels. The inclusion of interactions involving humans is a key focus, highlighting the need for their integration into ecology given the complex interactions between human activities and ecological systems in the Anthropocene. The comprehensive exploration in this theme issue sheds light on the interconnectedness of ecological systems and the importance of considering diverse interactions in understanding ecosystem dynamics. This article is part of the theme issue 'Connected interactions: enriching food web research by spatial and social interactions'. [ABSTRACT FROM AUTHOR]

Introduction: Increasing temperature of the global ocean alters the spatial behavior of a number of species. From the northern Atlantic Ocean, species may shift their area towards the poles. This results in the atlantification of the Barents Sea, raising questions about possible changes in species composition, community structure and community control. Methods: We address the question whether possible changes in community control can be detected and quantified based on simple network analytical measures applied to the food web. Based on unweighted (binary) and undirected (symmetric) data, we quantify the strength of direct and indirect interactions in the network, represent the most asymmetric effects in the asymmetry graph composed of directed and weighted links and study the overlap among trophic niches of organisms. Results and discussion: We support earlier findings suggesting that the ecosystem can possibly be characterized bywasp-waist control. Thiswouldmean that focusing management efforts on intermediate trophic levels is of high importance, providing indirect benefit for organisms also at lower and higher trophic levels. [ABSTRACT FROM AUTHOR]