Interactions among species shape the organization of life, influencing patterns of distribution, richness, behavior, and the partitioning of energy within ecosystems. Food webs are a central framework for studying these interactions, describing energy flow among organisms and the mechanisms governing community dynamics. A long-standing debate in network ecology concerns the relationship between complexity and stability, defined as a system’s ability to maintain or recover its original state following perturbations (Kratina et al., 2012). Temperature is a key driver of food web structure because it modulates metabolic rates, population dynamics, and species interactions (Brown et al., 2004); however, its effects on food web stability remain poorly understood.
This study investigates the relationship between complexity and stability in aquatic macroinvertebrate food webs, evaluating how temperature influences interaction structure and network dynamics. We hypothesized that temperate food webs were expected to exhibit lower species richness, larger-bodied organisms, fewer interactions, and higher energy flux per interaction, leading to increased stability through greater total biomass. In contrast, tropical food webs were predicted to show higher species richness, smaller organisms, and a larger number of interactions, with stability sustained by numerous weak, low–energy-flux links.
We conducted monthly sampling over one year in tropical streams (Intervales State Park, Brazil) and temperate ones (Stony Creek Watershed, USA). Macroinvertebrates were collected, identified, and their biomass estimated. Hypothetical food webs were reconstructed using a model based on functional feeding groups and predator–prey allometric relationships. For each food web, we quantified various complexity metrics and estimated stability.
Preliminary results indicated that temperate food webs exhibited higher species richness, larger average body size, and greater complexity across metrics, and were closer to stability than tropical ones. No direct relationship between complexity metrics and stability was detected in tropical networks. In contrast, temperate networks showed a positive association between average population body size and stability, suggesting that food webs become more stable as insects approach emergence and as community structure develops throughout the growing season. These findings enhance our understanding of the mechanisms regulating food web structure and stability and provide insights into how temperature may shape ecosystem persistence under ongoing climate change.