Destabilizing Effects of Environmental Stressors on Aquatic Communities and Interaction Networks across a Major River Basin

Abstract

Human-driven environmental stressors are increasingly threatening species survival and diversity of river systems worldwide. However, it remains unclear how the stressors affect the stability changes across aquatic multiple communities. Here, we used environmental DNA (eDNA) data sets from a humandominated river in China over 3 years and analyzed the stability changes in multiple communities under persistent anthropogenic stressors, including land use and pollutants. First, we found that persistent stressors significantly reduced multifaceted species diversity (e.g., species richness, Shannon's diversity, and Simpson's diversity) and species stability but increased species synchrony across multiple communities. Second, the structures of interaction networks inferred from an empirical meta-food web were significantly changed under persistent stressors, for example, resulting in decreased network modularity and negative/positive cohesion. Third, piecewise structural equation modeling proved that the persistent stress-induced decline in the stability of multiple communities mainly depended upon diversity-mediated pathways rather than the direct effects of stress per se; specifically, the increase of species synchrony and the decline of interaction network modularity were the main biotic drivers of stability variation. Overall, our study highlights the destabilizing effects of persistent stressors on multiple communities as well as the mechanistic dependencies, mainly through reducing species diversity, increasing species synchrony, and changing interaction networks.

Distinct multitrophic biodiversity composition and community organization in a freshwater lake and a hypersaline lake on the Tibetan Plateau

“… 66 , 67 Interestingly, a recent study of river food-web structure also showed decreased network modularity and negative:positive cohesion under persistent anthropogenic stressors. 68 Thus, our results suggest that the hypersaline lake ecosystem may be more vulnerable to environmental disturbances and may show stronger responses to climate changes in the coming decades.…”

Evaluating eDNA and eRNA metabarcoding for aquatic biodiversity assessment: From bacteria to vertebrates

“…This decline has prompted the emergence of the “Kunming-Montreal Global Biodiversity Framework,” which underscores the need for innovative biomonitoring approaches to bolster conservation efforts and enhance environmental management [ 2 ]. Complete taxonomic groups (from bacteria to fishes) and their multiple organization levels (from population to food web) all contribute to the functions and stability of the aquatic ecosystem and, thus, should be monitored conclusively [ 3 , 4 ]. These new monitoring demands cannot be met by morphology-based biomonitoring methods alone, and there is an urgent need for reliable methods capable of detecting diverse taxonomic groups to ensure accurate biodiversity assessments [ 5 , 6 ].…”