The interplay between network structure and functioning of detritus-based communities in patchy aquatic environment

Understanding models of networks formation is fundamental to explore the role of the structure in the functioning of the systems they describe, and their ability to respond to change. In this work, we aimed to understand whether and how the modular (or compartmented) structure of a network composed by macroinvertebrates and leaf detritus in six pools of aquatic system was related with the decomposition process. First, we evaluated the relationship between the temporal patterns of leaf detritus colonization and the modular subdivision of the network. Modularity was then related with the clustering of the pools based on convergent traits of leaf detritus consumption and environmental conditions. A significant relationship between the colonization patterns and the distribution of taxa and pools in well-defined modules was found. The modular and clustering subdivision of the pools showed a significant overlap, which revealed the intimate linkage between the structure and functioning of the system. Modularity shapes the functional architecture of the network, by increasing the spatial differences of leaf litter decomposition over time and the diversity of functional traits among detritus feeder. As a consequence, modularity influences the variability of communities’ responses to disturbance, increasing the diversity and robustness of functional processes. Our results have also implications from a conservation point of view, showing the importance of habitat heterogeneity for the robustness of ecosystem functioning, potentially enhancing biodiversity with positive, long-term effect on the whole food web.