scholarly journals Spatiotemporal Variations in Seston C:N:P Stoichiometry in a Large Eutrophic Floodplain Lake (Lake Taihu): Do the Sources of Seston Explain Stoichiometric Flexibility?

Water ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 36
Author(s):  
Jian Cai ◽  
Chengrong Bai ◽  
Xiangming Tang ◽  
Jiangyu Dai ◽  
Xingyu Jiang ◽  
...  
Keyword(s):  
Lake Taihu ◽  
Freshwater Ecosystems ◽  
Floodplain Lakes ◽  
Agricultural Watershed ◽  
Particulate Phosphorus ◽  
Floodplain Lake ◽  
Spatiotemporal Variations ◽  
Eutrophic Lakes ◽  
C:N:P Stoichiometry ◽  
Stoichiometric Ratios

Although sources of seston are much more complicated in lakes compared to oceans, the influences of different sources on the spatiotemporal variations in seston stoichiometry are still underexplored, especially in large eutrophic floodplain lakes. Here, we investigated seston stoichiometric ratios across a typical large eutrophic floodplain lake (Lake Taihu, East China) over one year. In addition, we used the n-alkane proxies to examine the influence of the seston source on seston stoichiometry variation. Throughout the study, the average value of the C:N:P ratio of 143:19:1 across Lake Taihu was close to the canonical lake’s ratios (166:20:1). Similar to other eutrophic lakes, seston C:N ratios varied the least across all environments, but C:P and N:P ratios varied widely and showed a strong decreasing trend in ratios of N:P and C:P from growing season to senescence season. This seasonal change was mainly associated with the decreasing contribution from algal-derived materials in seston pools because the non-algal dominated seston exhibited significantly lower ratios than algal-dominated seston. Furthermore, the spatial heterogeneity of stoichiometric ratios was also related to the seston source. During the senescence season, the terrestrial-dominated seston from agricultural watershed exhibited the lowest ratios in estuary sites compared with other areas. Statistically, the predictive power of environmental variables on stoichiometric ratios was strongly improved by adding n-alkanes proxies. Apart from source indicators, particulate phosphorus (PP) contents also partly explained the spatiotemporal variations in stoichiometric ratios. This study, thus, highlights the utility of multiple-combined n-alkane proxies in addition to simple C:N ratios to get more robust source information, which is essential for interpreting the spatiotemporal variations in seston stoichiometric ratios among eutrophic floodplain lakes and other freshwater ecosystems.

scholarly journals Effects of Cyanobacteria on Phosphorus Cycling and Other Aquatic Organisms in Simulated Eutrophic Ecosystems

Water ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 2265
Author(s):  
Peng Gu ◽  
Qi Li ◽  
Hao Zhang ◽  
Xin Luo ◽  
Weizhen Zhang ◽  
...  
Keyword(s):  
Nutrient Management ◽  
Lake Taihu ◽  
Cyanobacterial Bloom ◽  
Aquatic Organisms ◽  
Pilot Scale ◽  
Freshwater Ecosystems ◽  
Cyanobacterial Blooms ◽  
Eutrophic Lakes ◽  
P Concentration ◽  
Bloom Formation

Cyanobacterial blooms caused by eutrophication in Lake Taihu have led to ecological threats to freshwater ecosystems. A pilot scale experiment was implemented to investigate the relationship between cyanobacteria and other aquatic plants and animals in simulated eutrophic ecosystems under different phosphorus (P) regimes. The results of this study showed that cyanobacteria had two characteristics favorable for bloom formation in eutrophic ecosystems. One is the nutrient absorption. The presence of alkaline phosphatase was beneficial for algal cells in nutrition absorption under low P concentration. Cyanobacteria exhibited a stronger ability to absorb and store P compared to Vallisneria natans, which contributed to the fast growth of algal cells between 0.2 and 0.5 mg·L−1 of P (p < 0.05). However, P loads affected only the maximum biomass, but not the growth phases. The growth cycle of cyanobacteria remained unchanged and was not related to P concentration. P cycling indicated that 43.05–69.90% of the total P existed in the form of sediment, and P content of cyanobacteria showed the highest increase among the organisms. The other is the release of microcystin. Toxic microcystin-LR was released into the water, causing indirectly the growth inhibition of Carassius auratus and Bellamya quadrata and the reduction of microbial diversity. These findings are of importance in exploring the mechanism of cyanobacterial bloom formation and the nutrient management of eutrophic lakes.

scholarly journals Spatiotemporal Variations in Microcystin Concentrations and in the Proportions of Microcystin-Producing Cells in Several Microcystis aeruginosa Populations

2010 ◽  
Vol 76 (14) ◽  
pp. 4750-4759 ◽  
Author(s):  
M. Sabart ◽  
D. Pobel ◽  
E. Briand ◽  
B. Combourieu ◽  
M. J. Salençon ◽  
...  
Keyword(s):  
Microcystis Aeruginosa ◽  
Environmental Conditions ◽  
Real Time Pcr ◽  
Geographical Area ◽  
Freshwater Ecosystems ◽  
Cyanobacterial Blooms ◽  
Spatiotemporal Variations ◽  
Potential Toxicity ◽  
Genotype Composition ◽  
Over Time

ABSTRACT With the aim of explaining the variations in microcystin (MC) concentrations during cyanobacterial blooms, we studied several Microcystis aeruginosa populations blooming in different freshwater ecosystems located in the same geographical area. As assessed by real-time PCR, it appeared that the potentially MC-producing cells (mcyB +) were predominant (70 to 100%) in all of these M. aeruginosa populations, with the exception of one population in which non-MC-producing cells always dominated. Apart from the population in the Grangent Reservoir, we found that the proportions of potentially MC-producing and non-MC-producing cells varied little over time, which was consistent with the fact that according to a previous study of the same populations, the intergenic transcribed spacer (ITS) genotype composition did not change (38). In the Grangent Reservoir, the MC-RR variant was the dominant microcystin variant throughout the bloom season, despite changes in the ITS composition and in the proportions of mcyB + cells. Finally, the variations in total MC concentrations (0.3 to 15 μg liter−1) and in the MC cellular quotas (0.01 to 3.4 pg cell−1) were high both between and within sites, and no correlation was found between the MC concentrations and the proportion of mcyB + cells. All of these findings demonstrate that very different results can be found for the proportions of potentially MC-producing and non-MC-producing cells and MC concentrations, even in M. aeruginosa populations living in more or less connected ecosystems, demonstrating the importance of the effect of very local environmental conditions on these parameters and also the difficulty of predicting the potential toxicity of Microcystis blooms.

scholarly journals Spatial and Seasonal Variations in the Abundance of Nitrogen-Transforming Genes and the Microbial Community Structure in Freshwater Lakes with Different Trophic Statuses

2019 ◽  
Vol 16 (13) ◽  
pp. 2298 ◽  
Author(s):  
Yu Wan ◽  
Xiaohong Ruan ◽  
Jie Wang ◽  
Xiaojun Shi
Keyword(s):  
Microbial Community ◽  
Trophic Status ◽  
Lake Taihu ◽  
Quantitative Polymerase Chain Reaction ◽  
Amoa Gene ◽  
Functional Markers ◽  
Ammonia Oxidizing Bacteria ◽  
Eutrophic Lakes ◽  
Nirs Gene ◽  
Transforming Genes

Identifying nitrogen-transforming genes and the microbial community in the lacustrine sedimentary environment is critical for revealing nitrogen cycle processes in eutrophic lakes. In this study, we examined the diversity and abundance of ammonia-oxidizing bacteria (AOB), ammonia-oxidizing archaea (AOA), denitrifying bacteria (DNB), and anammox bacteria (AAOB) in different trophic status regions of Lake Taihu using the amoA, Arch-amoA, nirS, and hzo genes as functional markers. Quantitative Polymerase Chain Reaction (qPCR) results indicated that the abundance of the nirS gene was the highest, while the amoA gene had the lowest abundance in all regions. Except for the primary inflow area of Lake Taihu, Arch-amoA gene abundance was higher than the hzo gene in three lake bays, and the abundance of the nirS gene increased with decreasing trophic status. The opposite pattern was observed for the amoA, Arch-amoA, and hzo genes. Phylogenetic analyses showed that the predominant AOB and AOA were Nitrosomonas and Nitrosopumilus maritimus, respectively, and the proportion of Nitrosomonas in the eutrophic region (87.9%) was higher than that in the mesotrophic region (71.1%). Brocadia and Anammoxoglobus were the two predominant AAOB in Lake Taihu. Five novel unknown phylotypes of AAOB were observed, and Cluster AAOB-B was only observed in the inflow area with a proportion of 32%. In the DNB community, Flavobacterium occurred at a higher proportion (22.6–38.2%) in all regions, the proportion of Arthrobacter in the mesotrophic region (3.6%) was significantly lower than that in the eutrophic region (15.6%), and the proportions of Cluster DNB-E in the inflow area (24.5%) was significantly higher than that in the lake bay (7.3%). The canonical correspondence analysis demonstrated that the substrate concentration in sedimentary environments, such as NOx--N in the sediment, NH4+-N in the pore water, and the total organic matter, were the key factors that determined the nitrogen-transforming microbial community. However, the temperature was also a predominant factor affecting the AOA and AAOB communities.

Pyrosequencing analysis of free-living and attached bacterial communities in Meiliang Bay, Lake Taihu, a large eutrophic shallow lake in China

2015 ◽  
Vol 61 (1) ◽  
pp. 22-31 ◽  
Author(s):  
Xiangming Tang ◽  
Linlin Li ◽  
Keqiang Shao ◽  
Boweng Wang ◽  
Xianlei Cai ◽  
...  
Keyword(s):  
Bacterial Communities ◽  
Lake Taihu ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Eutrophic Lakes ◽  
Free Living ◽  
Bacterial Populations ◽  
Meiliang Bay ◽  
Taxonomic Groups ◽  
High Level

To elucidate the relationship between particle-attached (PA, ≥5.0 μm) and free-living (FL, 0.2–5.0 μm) bacterial communities, samplings were collected seasonally from November 2011 to August 2012 in Meiliang Bay, Lake Taihu, China. We used 454 pyrosequencing of 16S rRNA genes to study bacterial diversity and structure of PA and FL communities. The analysis rendered 37 985 highly qualified reads, subsequently assigned to 1755 operational taxonomic units (97% similarity) for the 8 samples. Although 27 high-level taxonomic groups were obtained, the 3 dominant phyla (Proteobacteria, Actinobacteria, and Bacteroidetes) comprised about 75.9% and 82.4% of the PA and FL fractions, respectively. Overall, we found no significant differences between community types, as indicated by ANOSIM R statistics (R = 0.063, P > 0.05) and the Parsimony test (P = 0.222). Dynamics of bacterial communities were correlated with changes in concentrations of total suspended solids (TSS) and total phosphorus (TP). In summer, a significant taxonomic overlap in the 2 size fractions was observed when Cyanobacteria, a major contributor of TSS and TP, dominated in the water, highlighting the potential rapid exchange between PA and FL bacterial populations in large shallow eutrophic lakes.

scholarly journals Effects of slope aspect on altitudinal pattern of soil C:N:P stoichiometry in alpine forest of Tibet

2021 ◽  
Vol 269 ◽  
pp. 01012
Author(s):  
Jiangrong Li ◽  
Qiqiang Guo ◽  
Heping Ma ◽  
Weilie Zheng
Keyword(s):  
Soil Temperature ◽  
Altitudinal Gradient ◽  
Sampling Site ◽  
Slope Aspect ◽  
C:N:P Stoichiometry ◽  
Soil C ◽  
Soil P ◽  
Soil Nutrition ◽  
Significant Difference ◽  
Stoichiometric Ratios

Knowledge of altitudinal patterns in soil C, N and P distribution is important for understanding biogeochemical processes in mountainous forests, yet the influence of slope aspects on soil stoichiometry has been largely neglected in previous studies. In this paper, a total number of 150 topsoil samples at four altitudes (3700, 3900, 4100, 4380 m a.s.l.) on sunny and shady slopes of Sygera mountains in the Southeastern Tibet were collected. Soil C, N and P contents, and pH, were measured. Soil temperature, moisture and richness of plant species were investigated at each sampling site. The results showed that: 1) in sunny slope, soil C, N and P concentrations increased with the increase in altitude, whereas soil C:N, C:P, and N:P decreased along the altitudinal gradient on s. Soil moisture was the main regulator of soil nutrition and stoichiometric ratios. 2) In shady slope, soil C and N contents had no significant difference along the altitudinal gradient except the higher values at low altitude, whereas soil P increased first and then decreased. Soil C:N increased with the increase in altitude, whereas C:P and N:P decreased first and then increased. Soil temperature and species richness were the main factors influencing soil nutrition and stoichiometric ratios. 3) Decoupling of soil C:N:P stoichiometry was observed in shady slope owing to changes in soil pH and temperature. 4) The rich contents of soil C and P were observed at two slopes along the altitudinal gradient, and high capacity of N supply existed at the topsoil in shady slope. These results suggested that slope aspect plays an important role in shaping the altitudinal pattern of soil C:N:P stoichiometry in mountainous forests.

scholarly journals Cyanopeptides Restriction and Degradation Co-mediate Microbiota Assembly During a Freshwater Cyanobacterial Harmful Algal Bloom (CyanoHAB)

2022 ◽  
Author(s):  
Han Gao ◽  
Ze Zhao ◽  
Lu Zhang ◽  
Feng Ju
Keyword(s):  
Community Assembly ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Algal Bloom ◽  
Lake Taihu ◽  
Harmful Algal Bloom ◽  
Size Fraction ◽  
Freshwater Ecosystems ◽  
Cyanobacterial Harmful Algal Blooms ◽  
Microbiota Diversity

Cyanobacterial harmful algal blooms (CyanoHABs) are globally intensifying and exacerbated by climate change and eutrophication. However, microbiota assembly mechanisms underlying CyanoHABs remain scenario specific and elusive. Especially, cyanopeptides, as a group of bioactive secondary metabolites of cyanobacteria, could affect microbiota assembly and ecosystem function. Here, the trajectory of cyanopeptides were followed and linked to microbiota during Microcystis-dominated CyanoHABs in lake Taihu, China. The most abundant cyanopeptide classes detected included microginin, spumigin, microcystin, nodularin and cyanopeptolin with total MC-LR-equivalent concentrations between 0.23 and 2051.54 ppb, of which cyanotoxins beyond microcystins (e.g., cyanostatin B and nodularin_R etc.) far exceeded reported organismal IC50 and negatively correlated with microbiota diversity, exerting potential collective eco-toxicities stronger than microcystins alone. The microbial communities were differentiated by size fraction and sampling date throughout CyanoHABs, and surprisingly, their variances were better explained by cyanopeptides (19-38%) than nutrients (0-16%). Cyanopeptides restriction (e.g., inhibition) and degradation are first quantitatively verified as the deterministic drivers governing community assembly, with stochastic processes being mediated by interplay between cyanopeptide dynamics and lake microbiota. This study presents an emerging paradigm in which cyanopeptides restriction and degradation co-mediate lake water microbiota assembly, unveiling new insights about the ecotoxicological significance of CyanoHABs to freshwater ecosystems.

Nitrate reduction in reactive swales at low temperatures: full-size field system vs. technical scale

2015 ◽  
Vol 15 (3) ◽  
pp. 642-648
Author(s):  
D. Wicke ◽  
P. Rouault ◽  
B. Krause Camilo ◽  
C. Pagotto ◽  
M. Dechesne ◽  
...  
Keyword(s):  
Drinking Water ◽  
Residence Time ◽  
Nitrate Reduction ◽  
Low Temperatures ◽  
Freshwater Ecosystems ◽  
Agricultural Watershed ◽  
Residence Times ◽  
Full Size ◽  
Field System ◽  
Nitrate Concentrations

Diffuse nitrate (NO3) contamination from intense agriculture adversely impacts freshwater ecosystems, and can also result in nitrate concentrations exceeding limits set in drinking water regulation, when receiving surface waters are used for drinking water production. Implementation of near-natural mitigation zones such as reactive swales or wetlands have been proven to be promising measures to reduce nitrate loads in agricultural drainage waters. However, the behavior of these systems at low temperatures and its dependence on system design has not been well known until now. In this study, the behavior of a full-scale (length: 45 m) reactive swale treating drainage water from an agricultural watershed in Brittany (France), with high nitrate concentrations in the receiving river, was monitored for one season (6 months). As flow in this full-size field system is usually restricted to winter and spring months (December–May), it usually operates at low water temperatures of 5–10 °C. Tracer tests revealed shorter than designed retention times due to high inflows and preferential flow in the swale. Results show a correlation between residence time and nitrate reduction with low removal (&lt;10%) for short residence times (&lt;0.1 day), increasing to &gt;25% at residence times &gt;10 h (0.4 day). Performance was compared to results of two technical-scale reactive swales (length: 8 m) operated for 1.5 years with two different residence times (0.4 and 2.5 days), situated at a test site of the German Federal Environmental Agency in Berlin (Germany). Similar nitrate reduction was observed for comparable temperature and residence time, showing that up-scaling is a suitable approach to transferring knowledge gathered from technical-scale experiments to field conditions. For the design of new mitigation systems, one recommendation is to investigate carefully the expected inflow volumes in advance to ensure a sufficient residence time for effective nitrate reduction at low temperatures.

scholarly journals Hydrological and hydrobotanic typology of the lake of North-Steppe Dnieper region

2019 ◽  
Vol 30 (2) ◽  
pp. 125-131
Author(s):  
N. O. Roshchyna ◽  
B. O. Baranovski
Keyword(s):  
Coniferous Forest ◽  
Steppe Zone ◽  
Large River ◽  
Floodplain Lakes ◽  
Floodplain Lake ◽  
Lake District ◽  
Anthropogenic Transformation ◽  
The Third ◽  
The North ◽  
National University

This article is devoted to the typology of lakes of the North-Steppe Dnieper. In developing the typology of lakes, the parameters were taken into account: landscape location, hydro-chemical and hydro-biological characteristics and the degree of their anthropogenic transformation. The data presented are based on the processing of stationary and route research materials from 1998 to 2018 on the lakes of river valleys: Dnieper, Samara, and Orel. Hydrological indicators are analyzed according to the literature, cartographic and archival data of the Dneprodiprovodkhoz Institute and the Biology Research Institute of Oles Honchar Dnipropetrovsk National University. Floristic studies were carried out using general botanical methods of collection and herbarization, and in the study of typical aquatic flora - special hydro-botanical methods. Geo-botanical studies were carried out according to geo-botanical and special hydro-botanical methods. The article presents the hydrological and hydro-botanical features of the lakes of the valley of a large river (Dnieper) and medium rivers (Samara, Orel). Lakes are located exclusively in valley-terrace landscapes in the northern part of the steppe zone of Ukraine. Despite this, based on cartographic materials, we proposed zoning of the territory of the lakes of the North-Steppe Dnieper according to the criteria: their location in lake regions, in various landscapes and the degree of anthropogenic transformation. The following districts and subareas were identified: Dnieper Lake District (Dnieper floodplain lake subarea with slight flooding of the floodplain, Dnieper Lake subarea of floodplain terraces, Dievsky floodplain lake subarea); Samara Lake District (Lake Subarea of Samara Coniferous forest, Lake Subarea of Estuary part of Samara); Orel Lake District. Lakes are located in various physical and geographical conditions of the floodplain, arena and third saline terrace. The typology of the lakes of the North-Steppe Dnieper basin was developed on the basis of regionalization of the location of the lakes, distribution according to the ecological and topographic profile, hydrological, hydro-chemical regimes, degree and nature of overgrowing. 11 types of lakes are identified based on the above criteria. 6 types were identified for the valley of a large river: floodplain lakes (3 types) with a long-flow regime, lakes of the second (sandy) terrace (2 types) and highly mineralized lakes of the third (saline) terrace. 5 types were identified for the valleys of middle rivers: floodplain lakes (3 types) with an episodic short-burial regime, lakes of the second (sandy) terrace (low-mineralized) and excessively mineralized lakes of the third (saline) terrace.

Dissolved organic carbon and relationship with bacterioplankton community composition in 3 lake regions of Lake Taihu, China

2014 ◽  
Vol 60 (10) ◽  
pp. 669-680 ◽  
Author(s):  
Xinghong Pang ◽  
Hong Shen ◽  
Yuan Niu ◽  
Xiaoxue Sun ◽  
Jun Chen ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Community Composition ◽  
Lake Taihu ◽  
Eutrophic Lakes ◽  
Bacterioplankton Community ◽  
Doc Concentration ◽  
Lake Center ◽  
Meiliang Bay ◽  
The Relationship

To clarify the relationships between dissolved organic carbon (DOC) and bacterioplankton community composition (BCC), a 1-year survey (June 2009 – May 2010) was conducted in 3 regions of Lake Taihu (Meiliang Bay, Lake Center, and Eastern Taihu), China. Polymerase chain reaction – denaturing gradient gel electrophoresis was used to analyze the composition and heterogeneity of the bacterioplankton community. Canonical correspondence analysis was used to explore the relationships between DOC concentration and BCC. We found a significant negative correlation between DOC concentration and bacterioplankton community diversity (as measured by the Shannon–Wiener index (H′)). The results show that spatial variation in the bacterioplankton population was stronger than the seasonal variation and that DOC concentration influences BCC in Lake Taihu. DOC concentration, followed by macrophyte biomass, water turbidity, and phytoplankton biomass were the most influential factors that account for BCC changes in Lake Taihu. More detailed studies on the relationship between DOC concentration and BCC should focus on differences in DOC concentrations and quality among these lake regions. DOC had a significant impact on BCC in Meiliang Bay. The relationship between DOC and BCC in the 2 other regions studied (Lake Center and Eastern Taihu) was weaker. The results of this study add to our understanding of the BCC in eutrophic lakes, especially regarding the role of the microbial loop in lake ecosystems.

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