Planktonic microorganisms have been recognized as important components in biogeochemical cycling in lakes.However,research into the impact of phyllosphere microorganisms,particularly those involved in carbon cycling,o...Planktonic microorganisms have been recognized as important components in biogeochemical cycling in lakes.However,research into the impact of phyllosphere microorganisms,particularly those involved in carbon cycling,on CO_(2) fluxes in macrophyte-dominated lakes within the context of global environmental changes remains scarce.Here,by employing high-throughput sequencing techniques,we experimentally tested how nutrient enrichment,top-down effects of fish and increases in dissolved organic carbon(DOC)affect CO_(2) exchange flux at the water-air interface by altering the community structure and functioning of phyllosphere bacteria on macrophytes.We found that our mesocosm ecosystems exhibited a net absorption of CO_(2),but nutrient enrichment significantly decreased the absorption ability.Mantel tests and multiple regression modeling also showed that eutrophication-associated parameters(total nitrogen,total phosphorus and ammonium nitrogen),pH,and extinction coefficient were the key drivers influencing abundance of phyllosphere functional microorganisms.In addition,these experimental treatments significantly altered the composition,diversity and co-occurrence networks of carbon cyclingassociated phyllosphere microorganisms,which impacted the CO_(2) flux.Structural equation models and linear regression further showed that the Shannon Index of phyllosphere functional microorganisms related to carbon cycling(rather than plant volume inhabited-PVI)had a significant positive impact on CO_(2) fixation.This means that environmental changes—especially eutrophication—may hinder carbon sequestration by decreasing the diversity of phyllosphere microorganisms rather than reducing the abundance of submerged macrophytes.This study increases our understanding of carbon cycling processes in aquatic environments from a management perspective by emphasizing the importance of protecting the diversity of phyllosphere microorganisms in macrophyte-dominated lakes.展开更多
Carbon resources play an important role in affecting the benthic bacterial community in shallow lakes. In this study, pyrosequencing was applied to compare bacteria phylogenic profile in incubated sediments with norma...Carbon resources play an important role in affecting the benthic bacterial community in shallow lakes. In this study, pyrosequencing was applied to compare bacteria phylogenic profile in incubated sediments with normal and exchanged organic detritus in macrophyte-dominated East Lake Taihu and algal-dominated Meiliang Bay. We observed significant bacteria species variations in sediments from two bays, regardless of treatments. RDA (Redundancy Analysis) analysis showed that sediment characteristics, especially concentrations of total nitrogen might account for this differentiation. Besides, algal-dominated Meiliang Bay sediment with addition of Vallisneria detritus exhibited higher bacterial species variations than the sediment amended with Microcystis detritus. To the contrary, sediments from macrophyte-dominated East Lake Taihu shared similar bacteria profile at all taxonomic levels and grouped together in MDS (multidimensional scaling) plots over the treatments with Vallisneria or Microcystis detritus addition into the sediment. We speculated that the different degradability of macrophyte detritus and algal detritus led to varied bacterial responses to exchanged organic resources and ultimately, the amounts, nutrient availability and degradability of organic resources may be main reasons for benthic bacteria community structure differentiation between the two states in shallow lakes.展开更多
基金financially supported by the National Natural Science Foundation of China(9225130432371644)Scientific Research and Innovation Project of Postgraduate Students in the Academic Degree of Yunnan University(KC-23233782).
文摘Planktonic microorganisms have been recognized as important components in biogeochemical cycling in lakes.However,research into the impact of phyllosphere microorganisms,particularly those involved in carbon cycling,on CO_(2) fluxes in macrophyte-dominated lakes within the context of global environmental changes remains scarce.Here,by employing high-throughput sequencing techniques,we experimentally tested how nutrient enrichment,top-down effects of fish and increases in dissolved organic carbon(DOC)affect CO_(2) exchange flux at the water-air interface by altering the community structure and functioning of phyllosphere bacteria on macrophytes.We found that our mesocosm ecosystems exhibited a net absorption of CO_(2),but nutrient enrichment significantly decreased the absorption ability.Mantel tests and multiple regression modeling also showed that eutrophication-associated parameters(total nitrogen,total phosphorus and ammonium nitrogen),pH,and extinction coefficient were the key drivers influencing abundance of phyllosphere functional microorganisms.In addition,these experimental treatments significantly altered the composition,diversity and co-occurrence networks of carbon cyclingassociated phyllosphere microorganisms,which impacted the CO_(2) flux.Structural equation models and linear regression further showed that the Shannon Index of phyllosphere functional microorganisms related to carbon cycling(rather than plant volume inhabited-PVI)had a significant positive impact on CO_(2) fixation.This means that environmental changes—especially eutrophication—may hinder carbon sequestration by decreasing the diversity of phyllosphere microorganisms rather than reducing the abundance of submerged macrophytes.This study increases our understanding of carbon cycling processes in aquatic environments from a management perspective by emphasizing the importance of protecting the diversity of phyllosphere microorganisms in macrophyte-dominated lakes.
文摘Carbon resources play an important role in affecting the benthic bacterial community in shallow lakes. In this study, pyrosequencing was applied to compare bacteria phylogenic profile in incubated sediments with normal and exchanged organic detritus in macrophyte-dominated East Lake Taihu and algal-dominated Meiliang Bay. We observed significant bacteria species variations in sediments from two bays, regardless of treatments. RDA (Redundancy Analysis) analysis showed that sediment characteristics, especially concentrations of total nitrogen might account for this differentiation. Besides, algal-dominated Meiliang Bay sediment with addition of Vallisneria detritus exhibited higher bacterial species variations than the sediment amended with Microcystis detritus. To the contrary, sediments from macrophyte-dominated East Lake Taihu shared similar bacteria profile at all taxonomic levels and grouped together in MDS (multidimensional scaling) plots over the treatments with Vallisneria or Microcystis detritus addition into the sediment. We speculated that the different degradability of macrophyte detritus and algal detritus led to varied bacterial responses to exchanged organic resources and ultimately, the amounts, nutrient availability and degradability of organic resources may be main reasons for benthic bacteria community structure differentiation between the two states in shallow lakes.
