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).