Cascade dams disrupt the river continuum,altering hydrology,biodiversity and nutrient flux.Describing the diversity of multi-trophic microbiota and assessing microbial contributions to the ecosystem processes are prerequisites for the restoration of these aquatic systems.This study investigated the microbial food web structure along a cascade-dammed river,paying special attention to the multi-trophic relationships and the potential role of pelagic-benthic coupling in nutrient cycles.Our results revealed the discontinuity in bacterial and eukaryotic community composition,functional group proportion,as well as α-diversity due to fragmentation by damming.The high microbial dissimilarity along the river,with the total multi-trophic β-diversity was 0.84,was almost completely caused by species replacement.Synchronization among trophic levels suggests potential interactions of the pelagic and the benthic groups,of which the β-diversities were primarily influenced by geographic and environmental factors,respectively.Dam-induced environmental variations,especially hydrological and nutrient variables,potentially influence the microbial food web via both top-down and bottom-up forces.We proposed that the cycles of carbon,nitrogen and phosphorus are influenced by multi-trophic groups through autotrophic and heterotrophic processes,predator-prey relationships,as well as the release of nutrients mainly by microfauna.Our results advance the notion that pelagic-benthic trophic coupling may intensify the accumulation of organic carbon,ammonium and inorganic phosphorus,thereby changing the biogeochemical patterns along river systems.As a consequence,researchers should pay more attention to the multi-trophic studies when assessing the environmental impacts,and to provide the necessary guidance for the ecological conservation and restoration of the dam-regulated systems.

Nan Yang;Linqiong Wang;Li Lin;Yi Li;Wenlong Zhang;Lihua Niu;Huanjun Zhang;Longfei Wang

Key Laboratory of Integrated Regulation and Resource Development on Shallow Lake of Ministry of Education,College of Environment,Hohai University,Nanjing 210098,China;College of Oceanography,Hohai University,Nanjing 210098,China;Department of Basin Water Environment,Changjiang River Scientific Research Institute,Wuhan 430010,China;Hubei Provincial Key Laboratory of Basin Water Resources and Ecological Environment Sciences,Changjiang River Scientific Research Institute,Wuhan 430010,China

环境科学与工程前沿

[1]Nan Yang;Linqiong Wang;Li Lin;Yi Li;Wenlong Zhang;Lihua Niu;Huanjun Zhang;Longfei Wang-.Pelagic-benthic coupling of the microbial food web modifies nutrient cycles along a cascade-dammed river)[J].环境科学与工程前沿,2022(04):125-137

Pelagic,dammed,Describing,microfauna

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