Global warming has caused an increase in the frequency and duration of droughts worldwide.Droughts could trigger large changes in physico-chemical conditions and phytoplankton community in waterbodies,resulting in a s...Global warming has caused an increase in the frequency and duration of droughts worldwide.Droughts could trigger large changes in physico-chemical conditions and phytoplankton community in waterbodies,resulting in a shift in the phytoplankton community.Spring diatom blooms in reservoirs have been increasingly observed in the past decade in the Taihu Lake basin.The aim of the present study is to elucidate the impacts of droughts on aquatic environment and to determine the driving factors for the succession of the phytoplankton functional groups based on the analysis of data collected during spring from 2009 to 2020 in the Daxi Reservoir.The unimodal relationship between 1-month aggregated precipitation index and phytoplankton species richness indicated the competitive exclusion occurred in extremely drought period.The structural equation modeling indicated that drought-related low water level conditions intensified sediment resuspension,and increased the phosphorus-enriched nonalgal turbidity in the Daxi Reservoir.Concurrently,a steady shift in the Reynolds phytoplankton functional groups from L 0,TD,J,X 2,and A(phytoplankton taxa preferring low turbidity and nutrient conditions)to TB(pennate diatoms being adapt to turbid and nutrient-rich conditions)was observed.The increased TP and non-algal turbidity in addition to the lowered disturbance contribute to the prevalence of Group TB.Considering the difficulties in nutrient control,timely water replenishment is often a feasible method of controlling the dominance of harmful algae for reservoir management.Finally,alternative water sources are in high demand for ensuring ecological safety and water availability when dealing with drought.展开更多
Reservoirs are an important water source in many densely populated areas in southwest China.Phytoplankton play an essential role in maintaining the structure and function of reservoir ecosystems.Understanding the succ...Reservoirs are an important water source in many densely populated areas in southwest China.Phytoplankton play an essential role in maintaining the structure and function of reservoir ecosystems.Understanding the succession in phytoplankton communities and the factors driving it are essential for eff ective water quality management in drinking water reservoirs.In this study,water samples were collected monthly at the surface layers from March 2016 to December 2019 in Hongfeng Reservoir,southwest China.The relationship between functional group succession was analyzed based on nonmetric multidimensional scaling analysis(NMDS),redundancy analysis(RDA),succession rate,and other analysis methods.The results showed distinct shifts in the community structure of phytoplankton functional groups within study period.The Cyclotella sp.was dominant in 2016 and 2017,and Pseudanabaena limnetica was the dominant group in 2018 and 2019.It appears that the phytoplankton composition and biomass are closely related to the water temperature and nutrient status in this reservoir.The results clearly showed that the permanganate index(COD_(Mn))was the key factor of dramatic phytoplankton functional group succession,and the change in succession rates was closely caused by total nitrogen concentration(TN).Therefore,the succession pattern and key factors of Hongfeng Reservoir revealed in this study were important guidance for the management of drinking water reservoirs in southwest China.A reasonable limit on exogenous nutrient input should be a priority,especially in high water temperature period.展开更多
揭示水生生态系统中浮游植物群落的构建机制,是有效预防藻类水华以及科学管理水生态系统的重要条件。为了揭示长江中下游通江湖泊鄱阳湖浮游植物群落的构建机制,以及明确驱动该湖泊浮游植物群落结构变化的具体影响因子,于2020年8月,对全...揭示水生生态系统中浮游植物群落的构建机制,是有效预防藻类水华以及科学管理水生态系统的重要条件。为了揭示长江中下游通江湖泊鄱阳湖浮游植物群落的构建机制,以及明确驱动该湖泊浮游植物群落结构变化的具体影响因子,于2020年8月,对全湖38个采样点的浮游植物及其功能群组成,以及环境因子进行调查分析。共检出7门59属91种,其中绿藻门(27属46种)、硅藻门(13属22种)和蓝藻门(8属11种)分别占总藻类种数的50.5%、24.2%和12.1%,其他门类占13.2%。浮游植物可划分为23个功能群,其中N、G、P、W1和LO为鄱阳湖优势功能群,它们所指示的生境特征表明鄱阳湖存在富营养化风险。鄱阳湖湖湾水域浮游植物群落结构与主航道水域存在明显差异,湖湾水域浮游植物Shannon-Wiener多样性指数、Simpson多样性指数和Pielou均匀度指数均显著高于主航道水域(Mann-Whitney U test,P<0.001)。群落距离与环境距离和地理距离的相关关系结果显示,环境过滤作用和空间扩散限制作用共同影响了鄱阳湖浮游植物及其功能群群落的构建,而变差分解分析、C-score分析和校正随机率分析结果进一步明确了确定性过程(环境过滤作用)占据主导地位且其对功能群群落影响更大。约束性排序分析结果显示,浊度、高锰酸盐指数和电导率是驱动鄱阳湖浮游植物群落结构变化的最重要环境因素,温度、电导率和高锰酸盐指数是影响鄱阳湖浮游植物功能群群落结构的主要环境因素。展开更多
Historical data indicate that the dominance of submerged plants in Dianchi Lake in the 1960 s was characterized by low algal density with dominance of non-toxic group J（Scenedesmus,Pediastrum,etc.）. The removal of s...Historical data indicate that the dominance of submerged plants in Dianchi Lake in the 1960 s was characterized by low algal density with dominance of non-toxic group J（Scenedesmus,Pediastrum,etc.）. The removal of submerged plants,which began in the 1970 s,resulted in the expansion of bloom-forming Microcystis（group M）. Laboratory experiments suggested that Microcystis aeruginosa was inclined to grow and develop at elevated temperatures. The growth of Scenedesmus obliquus was slower than that of co-cultivated M. aeruginosa in the absence of Ceratophyllum demersum,especially at higher temperatures. The existence of submerged plant C. demersum could inhibit the growth of the harmful algae M. aeruginosa and this inhibitory effect by C. demersum was enhanced with an increase in temperature. Instead,with C. demersum,the growth of S. obliquus was not inhibited,but the co-cultivated M. aeruginosa was eliminated in a short time. Combined with the historical data and laboratory experiments,it was indicated that the submerged plants might play important roles in the dominance of the non-toxic group J in the historical succession. Consequently,the introduction of the submerged plant such as C. demersum might alter the dominant phytoplankton functional groups from M to J and benefit the restoration of the eutrophic lake.展开更多
Objective:To study mortality of copepod Artemia franciscana against the occurrence of harmful marine algae and possible toxicological changes exhibited by binary and tertiary combinations of these harmful algae toxins...Objective:To study mortality of copepod Artemia franciscana against the occurrence of harmful marine algae and possible toxicological changes exhibited by binary and tertiary combinations of these harmful algae toxins.Methods:Tweenty four hours acute toxicity assays were performed with selected concentrations of Alexandrium minutum,Prorocentrum lima and Nitzschia N1c1 living cells.Additionally,the results were analyzed using the median-effect/combination index(CI)-isobologram equation to assess possible changes in the toxic effect induced by phytoplankton functional groups.Results:Biotoxin equivalent values obtained by immunodetection were(2.12±0.10),(8.60±1.30)and(4.32±1.67)pg/cell for saxitoxin,okadaic acid and domoic acid,respectively.The 24-h LC_(50) values estimated to saxitoxin and okadaic acid equivalents were 4.06 and 6.27μg/L,significantly below the value obtained for Nitzschia N1c1,which was established at 467.33μg/L.CI analysis applied on phytoplankton assemblages showed that both ternary mixture as the binary combinations exhibited antagonic action on toxic effects in Artemia nauplii,which were significantly lower than the toxic effect exhibited by each species studied.Conclusions:These results show that,although these harmful algae represent a serious risk to estuarine zooplankton community,the presence of phytoplankton functional groups within the same bloom can reduce the potential risk compared to the expected risk when each of the phytoplankton groups are evaluated individually.展开更多
基金Supported by the National Natural Science Foundation of China(Nos.U22A20616,32071573)。
文摘Global warming has caused an increase in the frequency and duration of droughts worldwide.Droughts could trigger large changes in physico-chemical conditions and phytoplankton community in waterbodies,resulting in a shift in the phytoplankton community.Spring diatom blooms in reservoirs have been increasingly observed in the past decade in the Taihu Lake basin.The aim of the present study is to elucidate the impacts of droughts on aquatic environment and to determine the driving factors for the succession of the phytoplankton functional groups based on the analysis of data collected during spring from 2009 to 2020 in the Daxi Reservoir.The unimodal relationship between 1-month aggregated precipitation index and phytoplankton species richness indicated the competitive exclusion occurred in extremely drought period.The structural equation modeling indicated that drought-related low water level conditions intensified sediment resuspension,and increased the phosphorus-enriched nonalgal turbidity in the Daxi Reservoir.Concurrently,a steady shift in the Reynolds phytoplankton functional groups from L 0,TD,J,X 2,and A(phytoplankton taxa preferring low turbidity and nutrient conditions)to TB(pennate diatoms being adapt to turbid and nutrient-rich conditions)was observed.The increased TP and non-algal turbidity in addition to the lowered disturbance contribute to the prevalence of Group TB.Considering the difficulties in nutrient control,timely water replenishment is often a feasible method of controlling the dominance of harmful algae for reservoir management.Finally,alternative water sources are in high demand for ensuring ecological safety and water availability when dealing with drought.
基金Supported by the National Natural Science Foundation of China(No.U1612442)the Science and Technology Foundation of Guizhou Province(Nos.[2020]6009,[2020]4Y009)Anton Brancelj was supported by Slovenian Research Agency(ARRS)(No.P1-0255)。
文摘Reservoirs are an important water source in many densely populated areas in southwest China.Phytoplankton play an essential role in maintaining the structure and function of reservoir ecosystems.Understanding the succession in phytoplankton communities and the factors driving it are essential for eff ective water quality management in drinking water reservoirs.In this study,water samples were collected monthly at the surface layers from March 2016 to December 2019 in Hongfeng Reservoir,southwest China.The relationship between functional group succession was analyzed based on nonmetric multidimensional scaling analysis(NMDS),redundancy analysis(RDA),succession rate,and other analysis methods.The results showed distinct shifts in the community structure of phytoplankton functional groups within study period.The Cyclotella sp.was dominant in 2016 and 2017,and Pseudanabaena limnetica was the dominant group in 2018 and 2019.It appears that the phytoplankton composition and biomass are closely related to the water temperature and nutrient status in this reservoir.The results clearly showed that the permanganate index(COD_(Mn))was the key factor of dramatic phytoplankton functional group succession,and the change in succession rates was closely caused by total nitrogen concentration(TN).Therefore,the succession pattern and key factors of Hongfeng Reservoir revealed in this study were important guidance for the management of drinking water reservoirs in southwest China.A reasonable limit on exogenous nutrient input should be a priority,especially in high water temperature period.
文摘揭示水生生态系统中浮游植物群落的构建机制,是有效预防藻类水华以及科学管理水生态系统的重要条件。为了揭示长江中下游通江湖泊鄱阳湖浮游植物群落的构建机制,以及明确驱动该湖泊浮游植物群落结构变化的具体影响因子,于2020年8月,对全湖38个采样点的浮游植物及其功能群组成,以及环境因子进行调查分析。共检出7门59属91种,其中绿藻门(27属46种)、硅藻门(13属22种)和蓝藻门(8属11种)分别占总藻类种数的50.5%、24.2%和12.1%,其他门类占13.2%。浮游植物可划分为23个功能群,其中N、G、P、W1和LO为鄱阳湖优势功能群,它们所指示的生境特征表明鄱阳湖存在富营养化风险。鄱阳湖湖湾水域浮游植物群落结构与主航道水域存在明显差异,湖湾水域浮游植物Shannon-Wiener多样性指数、Simpson多样性指数和Pielou均匀度指数均显著高于主航道水域(Mann-Whitney U test,P<0.001)。群落距离与环境距离和地理距离的相关关系结果显示,环境过滤作用和空间扩散限制作用共同影响了鄱阳湖浮游植物及其功能群群落的构建,而变差分解分析、C-score分析和校正随机率分析结果进一步明确了确定性过程(环境过滤作用)占据主导地位且其对功能群群落影响更大。约束性排序分析结果显示,浊度、高锰酸盐指数和电导率是驱动鄱阳湖浮游植物群落结构变化的最重要环境因素,温度、电导率和高锰酸盐指数是影响鄱阳湖浮游植物功能群群落结构的主要环境因素。
基金supported by the National Natural Science Foundation of China (No.31370472)the State Key Laboratory of Freshwater Ecology and Biotechnology (No.2014FBZ01)the Major Science and Technology Program for Water Pollution Control and Treatment (No.2013ZX07102-005)
文摘Historical data indicate that the dominance of submerged plants in Dianchi Lake in the 1960 s was characterized by low algal density with dominance of non-toxic group J（Scenedesmus,Pediastrum,etc.）. The removal of submerged plants,which began in the 1970 s,resulted in the expansion of bloom-forming Microcystis（group M）. Laboratory experiments suggested that Microcystis aeruginosa was inclined to grow and develop at elevated temperatures. The growth of Scenedesmus obliquus was slower than that of co-cultivated M. aeruginosa in the absence of Ceratophyllum demersum,especially at higher temperatures. The existence of submerged plant C. demersum could inhibit the growth of the harmful algae M. aeruginosa and this inhibitory effect by C. demersum was enhanced with an increase in temperature. Instead,with C. demersum,the growth of S. obliquus was not inhibited,but the co-cultivated M. aeruginosa was eliminated in a short time. Combined with the historical data and laboratory experiments,it was indicated that the submerged plants might play important roles in the dominance of the non-toxic group J in the historical succession. Consequently,the introduction of the submerged plant such as C. demersum might alter the dominant phytoplankton functional groups from M to J and benefit the restoration of the eutrophic lake.
基金Supported by Spanish Government(CTM2012-34757)the Mexican UMSNH University(CIC/11/301).
文摘Objective:To study mortality of copepod Artemia franciscana against the occurrence of harmful marine algae and possible toxicological changes exhibited by binary and tertiary combinations of these harmful algae toxins.Methods:Tweenty four hours acute toxicity assays were performed with selected concentrations of Alexandrium minutum,Prorocentrum lima and Nitzschia N1c1 living cells.Additionally,the results were analyzed using the median-effect/combination index(CI)-isobologram equation to assess possible changes in the toxic effect induced by phytoplankton functional groups.Results:Biotoxin equivalent values obtained by immunodetection were(2.12±0.10),(8.60±1.30)and(4.32±1.67)pg/cell for saxitoxin,okadaic acid and domoic acid,respectively.The 24-h LC_(50) values estimated to saxitoxin and okadaic acid equivalents were 4.06 and 6.27μg/L,significantly below the value obtained for Nitzschia N1c1,which was established at 467.33μg/L.CI analysis applied on phytoplankton assemblages showed that both ternary mixture as the binary combinations exhibited antagonic action on toxic effects in Artemia nauplii,which were significantly lower than the toxic effect exhibited by each species studied.Conclusions:These results show that,although these harmful algae represent a serious risk to estuarine zooplankton community,the presence of phytoplankton functional groups within the same bloom can reduce the potential risk compared to the expected risk when each of the phytoplankton groups are evaluated individually.
