CONCLUSION
Freshwater ecosystems are particularly vulnerable to climate change and human pressure (Ledger et al. 2013; Reid et al. 2018). Here, we demonstrate a decline in energy flux at the whole-network level. Such decline occurs across multiple trophic compartments, suggesting a loss of multiple food web functions such as carnivory, detritivory, and omnivory. We show retention in energy flux towards the base of the food-web over time, indicating that riverine food webs underwent considerable restructuring in trophic height and the distribution of energy fluxes over time. This should cause impacts on ecosystem services. For instance, large carnivores provide a rich resource of protein and financial support for human well-being (Pelicice et al. 2022). We show that human footprint has strong negative effects on diversity and energy flux in fish food webs, which becomes stronger over time as human influence intensifies. Our findings illustrate that conserving the functioning of food webs in riverine ecosystems will be a major challenge as human pressures continue to increase worldwide (Reid et al. 2018).