Food webs speak of human impact: Using stable isotope-based tools to measure ecological consequences of environmental change

Linking their major biotic and abiotic components, food webs form the core of ecosystems, many of which are today exposed to multiple human impacts acting at several spatial and temporal scales. A food web perspective allows for a quantification of environmental change effects on both the structure of biological diversity and the functioning of ecosystems. Food web metrics based on stable isotope analysis (SIA) represent a promising way for an integrative assessment of these responses. While showing high sensitivity to environmental change, they are, however, rarely presented and discussed within a systematic mechanistic and hypothesis-driven framework. Here we first provide a global overview of anthropogenic impact types, their effects on food webs and the associated ecological mechanisms. Based on published studies from terrestrial, freshwater and marine ecosystems, we then demonstrate the versatility of SIA-based metrics, allowing for quantification of several key food web attributes and applicable across a wide range of human-induced impacts such as eutrophication, pollution, introduction of exotic species or connectivity interruption. We finally propose a guiding framework to make SIA application in the studies of anthropogenic impact on food webs more rigorous and enhance its potential for producing novel insights.