Towards a framework for predicting arctic food web response to global climate change

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The climate of the Arctic is currently changing faster than that of any other part of the globe. While impacts at the population level are increasingly well described, we know little about changes at the level of trophic interactions among populations, and of resultant changes in food web structure. Such changes have been hypothesized to affect the stability, dynamics and functioning of arctic communities. Of particular concern are changes in the food web modules dominating the Arctic in terms of both biomass and diversity, i.e. the arthropods. Despite their presumed contribution to ecosystem functioning, trophic interactions between arctic arthropods have so far been largely neglected. Within high-arctic food webs, wolf spiders maintain a rare role as arthropod top predators. With changes in populations at lower trophic levels, these spiders are then expected to be massively affected by arctic change - with effects percolating across the webs. Studies of trophic interactions between these spiders and other parts of the food web may therefore offer key insights into the community- and ecosystem-level effects of arctic change. In this project, I will use novel techniques to expose key mechanisms linking environmental change to food web structure and dynamics. In particular, I will quantify the feeding ecology of wolf spiders by combining DNA-based molecular faeces analysis and functional response models. To ground-truth the resultant models, I will quantify local food web structure along an altitude gradient, chosen to represent variation in microclimatic conditions as predicted by IPCC climate scenarios. Overall, I expect this combination of cutting-edge molecular techniques, parameterised functional models and empirical quantifications of food web structure to offer a fundamentally new approach to understanding the functional consequences of arctic change.