Effects of climate and human pressures on ecological network structure and energy flows in major Brazilian wetlands

Abstract

The decline in global biodiversity with increasing human pressures has raised concerns about the risk that species losses pose to the functioning of natural ecosystems. Because trophic interactions modulate the functioning of natural ecosystems, it has been proposed that for a generalization about the extent of biodiversity effects in natural ecosystems, studies with multitrophic perspectives and at different geographic scales are needed. Ecological networks approach is a important tool for understand the structure and functioning of natural ecosystems, as it allows connecting biodiversity and ecosystem functioning through energy flows. However, studies employing ecological networks approach and energy flux in spatially extensive and hyperdiverse ecosystems such as wetlands remain lacking. In this study, we will use data from fish species of multiple feeding guilds sampled from 72 lakes of four major Brazilian wetlands (Amazon, Araguaia, Pantanal and Paraná) to investigate how human pressures and climate influence the ecological network structure and energy flow through trophic compartments. Combining empirical dietary data and mathematical models we will construct interaction networks between fish species, and from these networks we will use an energy ecology approach (assimilation rates, metabolism etc.) to calculate energy fluxes through fish species. Finally, we will apply structural equation models to unveil the direct and indirect effects (via biodiversity and network metrics) of climate and human pressures on energy fluxes. It is expected that our results provide empirical evidence of how the architecture of ecological interactions affects the functioning of natural ecosystems and generate a predictive framework of how increasing human pressures and climate changes could affect ecosystem functioning via trophic simplification.