Drought rewires the cores of food webs

Abstract

Droughts are intensifying under climate change. Research into the resilience of stream food webs to drought now shows that ‘rewiring’ of food web structure in the face of species losses helps to buffer changes to the overall network structure. Droughts are intensifying across the globe1,2, with potentially devastating implications for freshwater ecosystems3,4. We used new network science approaches to investigate drought impacts on stream food webs and explored potential consequences for web robustness to future perturbations. The substructure of the webs was characterized by a core of richly connected species5 surrounded by poorly connected peripheral species. Although drought caused the partial collapse of the food webs6, the loss of the most extinction-prone peripheral species triggered a substantial rewiring of interactions within the networks’ cores. These shifts in species interactions in the core conserved the underlying core/periphery substructure and stability of the drought-impacted webs. When we subsequently perturbed the webs by simulating species loss in silico, the rewired drought webs were as robust as the larger, undisturbed webs. Our research unearths previously unknown compensatory dynamics arising from within the core that could underpin food web stability in the face of environmental perturbations.