Phytoplankton functional groups have gained increasing attention in recent years.To understand the composition of phytoplankton functional groups in Poyang Lake and their drivers,field investigations were conducted ov...Phytoplankton functional groups have gained increasing attention in recent years.To understand the composition of phytoplankton functional groups in Poyang Lake and their drivers,field investigations were conducted over three years:2013,2014,and 2016.Phytoplankton were dominated by diatoms,contributing from 20.19%to 57.57%of the total biomass,followed by cyanobacteria,9.81%-39.98%.Microcystis sp.and Anabaena sp.were the dominant species among cyanobacteria.Twenty-six functional groups were identified among 72 genera or species,and fiver groups(P,B,MP,H1,and G)were categorized dominant.All of dominant groups except H1 were tolerate highly fluctuating mixing intensities and showed a typical monthly succession variation.Water temperature,water level,and nutrients are key drivers for the variation of phytoplankton communities at taxonomic and functional levels.Both of redundancy and variation partitioning analyses showed that environmental variables might explain functional groups better than taxonomic communities,implying that the functional groups were more advantageous in showing the effects of environmental conditions than taxonomic compositions.Hydrological conditions have a crucial influence on phytoplankton assemblage dynamics in highly variable water regime lakes,but not in the largest ones.The functional groups method is suitable for identifying the spatial and seasonal characteristics of aquatic environments that significantly affected by water regimes.展开更多
Aims In a large dam-regulated reservoir with regular hydrological pattern and strong flooding gradients across shore elevations,plants inhabiting in different shore elevations have to confront long-lasting flooding of...Aims In a large dam-regulated reservoir with regular hydrological pattern and strong flooding gradients across shore elevations,plants inhabiting in different shore elevations have to confront long-lasting flooding of differential in tensities every year.Such persistent stress may lead to intraspecific differentiation of flooding tolerance in seeds.Echinochloa crusgalli var.zelayensis is a dominant annual plant in the shores of the Three Gorges Reservoir(TGR),which plays an important role in the shore vegetation.The objective of this study is to check whether intraspecific differentiation of seed flooding tolerance has occurred among E.crusgalli var.zelayensis populations in the TGR shores and whether such differentiation is associated with weak seed dispersal.Methods We collected seeds of E.crusgalli var.zelayensis from different populations in the TGR shores,and then placed them at four elevations in the shores flooded by reservoir impoundment.Parameters reflecting seed flooding tolerance including post-flooding percentage of intact seeds,seed germinability and seedling emergence rate were investigated for the seeds from different populations and undergoing flooding of different intensities.Floating time of seeds and speed of water level rise during impoundment were examined,and used to quantify dispersal potential of seeds in the shores of the TGR when flooded.Important Findings Both intact seed percentage and final seedling emergence rate after flooding significantly declined with increasing shore elevations where the seeds were collected,indicating that intraspecific differentiation in seed flooding tolerance has occurred among E.crusgalli var.zelayensis populations in the TGR shores after 7-year operation of the reservoir.The distanee of seeds transported by rising water during reservoir impoundment was limited due to short-floating time of the seeds and relatively low speed of water level rise in the reservoir.This would be favourable to the development of intraspecific differentiation in seed flooding tolerance.展开更多
基金Supported by the Science and Technology Project of Jiangxi Provincial Department of Education(Nos.GJJ211938,GJJ211933)the National Natural Science Foundation of China(No.52260026)+2 种基金the Science and Technology Research and Development Project of China Railway Group Limited(No.2021-Major-08)the Major Science and Technology Program of Jiangxi Provincial Department of Water Resources(No.202224ZDKT22)the Young Talents Training Project of Jiangxi Province(No.20204BCJL23040)。
文摘Phytoplankton functional groups have gained increasing attention in recent years.To understand the composition of phytoplankton functional groups in Poyang Lake and their drivers,field investigations were conducted over three years:2013,2014,and 2016.Phytoplankton were dominated by diatoms,contributing from 20.19%to 57.57%of the total biomass,followed by cyanobacteria,9.81%-39.98%.Microcystis sp.and Anabaena sp.were the dominant species among cyanobacteria.Twenty-six functional groups were identified among 72 genera or species,and fiver groups(P,B,MP,H1,and G)were categorized dominant.All of dominant groups except H1 were tolerate highly fluctuating mixing intensities and showed a typical monthly succession variation.Water temperature,water level,and nutrients are key drivers for the variation of phytoplankton communities at taxonomic and functional levels.Both of redundancy and variation partitioning analyses showed that environmental variables might explain functional groups better than taxonomic communities,implying that the functional groups were more advantageous in showing the effects of environmental conditions than taxonomic compositions.Hydrological conditions have a crucial influence on phytoplankton assemblage dynamics in highly variable water regime lakes,but not in the largest ones.The functional groups method is suitable for identifying the spatial and seasonal characteristics of aquatic environments that significantly affected by water regimes.
基金supported by the National Key R&D Program of China(2017YFC0505304)National Natural Science Foundation of China(31770465,31370443)Chongqing Municipal Key R&D Program(cstc2018jszx-zdyfxmX0021-01).
文摘Aims In a large dam-regulated reservoir with regular hydrological pattern and strong flooding gradients across shore elevations,plants inhabiting in different shore elevations have to confront long-lasting flooding of differential in tensities every year.Such persistent stress may lead to intraspecific differentiation of flooding tolerance in seeds.Echinochloa crusgalli var.zelayensis is a dominant annual plant in the shores of the Three Gorges Reservoir(TGR),which plays an important role in the shore vegetation.The objective of this study is to check whether intraspecific differentiation of seed flooding tolerance has occurred among E.crusgalli var.zelayensis populations in the TGR shores and whether such differentiation is associated with weak seed dispersal.Methods We collected seeds of E.crusgalli var.zelayensis from different populations in the TGR shores,and then placed them at four elevations in the shores flooded by reservoir impoundment.Parameters reflecting seed flooding tolerance including post-flooding percentage of intact seeds,seed germinability and seedling emergence rate were investigated for the seeds from different populations and undergoing flooding of different intensities.Floating time of seeds and speed of water level rise during impoundment were examined,and used to quantify dispersal potential of seeds in the shores of the TGR when flooded.Important Findings Both intact seed percentage and final seedling emergence rate after flooding significantly declined with increasing shore elevations where the seeds were collected,indicating that intraspecific differentiation in seed flooding tolerance has occurred among E.crusgalli var.zelayensis populations in the TGR shores after 7-year operation of the reservoir.The distanee of seeds transported by rising water during reservoir impoundment was limited due to short-floating time of the seeds and relatively low speed of water level rise in the reservoir.This would be favourable to the development of intraspecific differentiation in seed flooding tolerance.
