The reconstruction of paleovegetation and paleoclimate requires an understanding of the relationships between surface pollen assemblages and modern vegetation and climate.Here,we analyzed the characteristics of surfac...The reconstruction of paleovegetation and paleoclimate requires an understanding of the relationships between surface pollen assemblages and modern vegetation and climate.Here,we analyzed the characteristics of surface pollen assemblages across different vegetation zones in the Tianshan Mountains.Using surface pollen analysis and vegetation sample surveys at 75 sites on the northern slopes of the Tianshan Mountains,we determined the correlation between the percentage of dominant pollen types and the corresponding vegetation cover.Redundancy analysis was used to investigate the relationships between surface pollen assemblages and environmental factors.Our results show that the Tianshan Mountains contain several distinct ecological regions,which can be divided into five main vegetation zones from low to high altitudes:mountain desert zone(Hutubi County(HTB):500-1300 m;Qitai County(QT):1000-1600 m),mountain steppe zone(HTB:1400-1600 m;QT:1650-1800 m),mountain forest zone(HTB:1650-2525 m;QT:1850-2450 m),subalpine meadow zone(HTB:2550-2600 m;QT:2500-2600 m),and alpine mat vegetation zone(HTB:2625-2700 m;QT:2625-2750 m).The surface pollen assemblages of different vegetation zones can accurately reflect the characteristics of the mountainous vegetation patterns on the northern slopes of the Tianshan Mountains when excluding the widespread occurrence of Chenopodiaceae,Artemisia,and Picea pollen.Both average annual precipitation(P_(ann))and annual average temperature(T_(ann))affect the distribution of surface pollen assemblages.Moreover,P_(ann) is the primary environmental factor affecting surface pollen assemblages in this region.A significant correlation exists between the pollen percentage and vegetation cover of Picea,Chenopodiaceae,Artemisia,and Asteraceae.Moreover,Picea,Chenopodiaceae,and Artemisia pollen are over-represented compared with their corresponding vegetation cover.The Asteraceae pollen percentage roughly reflects the distribution of a species within the local vegetation.These results have important implications for enhancing our understanding of the relationship between surface pollen assemblages and modern vegetation and climate.展开更多
Effects of the heavy metal copper(Cu), the metalloid arsenic(As), and the antibiotic oxytetracycline(OTC) on bacterial community structure and diversity during cow and pig manure composting were investigated. Eight tr...Effects of the heavy metal copper(Cu), the metalloid arsenic(As), and the antibiotic oxytetracycline(OTC) on bacterial community structure and diversity during cow and pig manure composting were investigated. Eight treatments were applied, four to each manure type, namely cow manure with:(1) no additives(control),(2) addition of heavy metal and metalloid,(3) addition of OTC and(4) addition of OTC with heavy metal and metalloid;and pig manure with:(5) no additives(control),(6) addition of heavy metal and metalloid,(7) addition of OTC and(8) addition of OTC with heavy metal and metalloid. After 35 days of composting, according to the alpha diversity indices, the combination treatment(OTC with heavy metal and metalloid) in pig manure was less harmful to microbial diversity than the control or heavy metal and metalloid treatments. In cow manure, the treatment with heavy metal and metalloid was the most harmful to the microbial community, followed by the combination and OTC treatments. The OTC and combination treatments had negative effects on the relative abundance of microbes in cow manure composts. The dominant phyla in both manure composts included Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria. The microbial diversity relative abundance transformation was dependent on the composting time. Redundancy analysis(RDA) revealed that environmental parameters had the most influence on the bacterial communities. In conclusion, the composting process is the most sustainable technology for reducing heavy metal and metalloid impacts and antibiotic contamination in cow and pig manure. The physicochemical property variations in the manures had a significant effect on the microbial community during the composting process. This study provides an improved understanding of bacterial community composition and its changes during the composting process.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
We characterized variations in bacterioplankton community composition(BCC) in mesocosms subject to three different treatments. Two groups contained fish(group one: Cyprinus carpio; group two: Hypophthalmichthys molitr...We characterized variations in bacterioplankton community composition(BCC) in mesocosms subject to three different treatments. Two groups contained fish(group one: Cyprinus carpio; group two: Hypophthalmichthys molitrix); and group three, the untreated mesocosm, was the control. Samples were taken seven times over a 49-d period, and BCC was analyzed by PCR-denaturing gradient gel electrophoresis(DGGE) and real-time quantitative PCR(q PCR). Results revealed that introduction of C. carpio and H. molitrix had a remarkable impact on the composition of bacterioplankton communities, and the BCC was significantly diff erent between each treatment. Sequencing of DGGE bands revealed that the bacterioplankton community in the different treatment groups was consistent at a taxonomic level, but differed in its abundance. H. molitrix promoted the richness of Alphaproteobacteria and Actinobacteria, while more bands affiliated to Cyanobacteria were detected in C. carpio mesocosms. The redundancy analysis(RDA) result demonstrated that the BCC was closely related to the bottom-up(total phosphorus, chlorophyll a, phytoplankton biomass) and top-down forces(biomass of copepods and cladocera) in C. carpio and control mesocosms, respectively. We found no evidence for top-down regulation of BCC by zooplankton in H. molitrix mesocosms, while grazing by protozoa(heterotrophic nanoflagellates, ciliates) became the major way to regulate BCC. Total bacterioplankton abundances were significantly higher in C. carpio mesocosms because of high nutrient concentration and suspended solids. Our study provided insights into the relationship between fish and bacterioplankton at species level, leading to a deep understanding of the function of the microbial loop and the aquatic ecosystem.展开更多
Tillage practices and organic amendment are strategies used worldwide to preserve the properties and fertility of soils.This study aimed to elucidate effects of 3-year field treatments of tillage practice and straw ma...Tillage practices and organic amendment are strategies used worldwide to preserve the properties and fertility of soils.This study aimed to elucidate effects of 3-year field treatments of tillage practice and straw management on physical properties of Mollisols,root architecture and maize yield in northeast China.The experiment was conducted from 2015 to 2018 following a splitplot design of a randomized complete block with tillage practices[rotary tillage(R)and deep tillage(D)]as main plots and straw managements[straw returning(S),straw returning and organic fertilizer(M),straw removal(T)]as subplots.Soil samples at 0-15,15-30,30-50 cm depths and root samples at the seedling stage were collected.The results showed that DM treatment significantly improved soil moisture content at 10-50 cm soil depth and decreased soil compaction(P<0.05),which led to a better root architecture.Rotary tillage had a slower thermal conductivity but better thermal insulation performance,while deep tillage showed a higher daily temperature difference.Bulk density of topsoil was significantly lower in DS(1.16 g·cm^(-3))than in other treatments,but the soil permeability in DS(1.40 mm·min^(-1)in 0-15 soil depth and 1.45 mm·min-1in 15-30 cm soil depth)was the highest.At the maize seedling stage,DM had the highest root dry weight,root-shoot ratio and root length,while RM had the highest root volume,root furcation number and root tip number.The maize yield of three years in DM was 6.19%,5.21%and 15.72%higher than that in DS,DT and RM(P<0.01),respectively.Relative to RT and DT,a slight decrease(2.72%and 0.93%,respectively)in maize yield under RS and DS was observed,which could be alleviated by the addition of organic fertilizer.The correlation matrix indicated that kernel per ear number and 100-kernel weight were the dominant factors that affected maize yield.Redundancy analysis suggested that straw managements and tillage practices were significantly positively correlated with root-shoot ratio,root dry weight,maximum root length,the total root length and maize yield,but significantly negatively correlated with soil compaction,bulk density,soil moisture content and soil temperature.Among all the treatments,deep tillage with straw returning and the addition of organic fertilizer was recommended as a promising strategy in restoring soil productivity,promoting maize growth and increasing maize yield in Mollisols of northeast China and similar regions around the world.展开更多
Objective:Gastrointestinal heat retention syndrome(GHRS)is associated with lung-heat syndrome and is related to recurrent respiratory infection.Upper respiratory tract infection(URTI)lung heat syndrome is common in ch...Objective:Gastrointestinal heat retention syndrome(GHRS)is associated with lung-heat syndrome and is related to recurrent respiratory infection.Upper respiratory tract infection(URTI)lung heat syndrome is common in children.The study will explore the effect of GHRS on the structure and function of gut microbiota in children with URTI lung-heat syndrome.Methods:Participants were divided into both groups using the self-developed URTI scale and the“GHRS Diagnostic Scale$Pediatric Part”:GHRS-positive children(LS group)and GHRS-negative children(L group).General information,clinical symptoms,and stool were collected.We used 16S rRNA amplicon sequencing technology to determine the gene sequence of the V3eV4 region in feces and measure the gut microbiota of the both groups at the genus level.Results:A total of 23 children were included in the both groups.There were 12 cases in the LS group and 11 cases in the L group.There was no statistical difference between the both groups in age,gender,height,weight,and body mass index.The effective sequences shared by the both groups accounted for 85.66%of the total.In the gut microbiota,there was no difference in the a diversity and the b diversity between the both groups.Compared with the L group,the LS group had a significant increase in the relative abundance of the Ruminococcus gnavus group,Prevotella-9,Staphylococcus,and Actinomyces(P<.05).The functions of the both groups of microbiota primarily concentrate on metabolism,genetic information processing,and environmental information processing.The relative abundance of signaling molecules and interactions in the LS group were higher than that in the L group(P<.05).The redundancy analysis(RDA)showed that the URTI score had the greatest impact on the distribution of microbiota.Conclusion:GHRS may affect the development of URTI lung-heat syndrome by changing the relative abundances of gut microbiota.展开更多
The insufficient supply of phosphorus is the main problem facing agriculture and forestry production in red soil region of southern China.To investigate whether applying bag-controlled slow-release fertilizer can impr...The insufficient supply of phosphorus is the main problem facing agriculture and forestry production in red soil region of southern China.To investigate whether applying bag-controlled slow-release fertilizer can improve the phosphorus availability and available phosphorus component content,with Gaofeng State-owned Eucalyptus Plantations Forest Farm in Guangxi red soil region as the research object,comparative test of different fertilizer types and fertilizer amount of bag-controlled slow-release fertilizer with conventional fertilization(G1),bag-controlled slow-release fertilizer with reducing fertilization(G2),traditional compound fertilizer(G3),basal fertilizer(G4),and no fertilization(G5)was designed.Soil phosphorus classification method was used to determine the content of phosphorus components in the soil,and redundancy analysis was used to study the effects of components on tree growth.The results showed that:compared with traditional fertilization,bag-controlled slow-release fertilizer significantly increased the contents of AP,Pi,Fe-P and other components in soil;the phosphorus activation coefficients of G2 and G1 were significantly higher than those of the other three treatments,and the order was G2>G1>G4>G5>G3;redundancy analysis showed that PAC and Fe-P had the most significant effect on plant growth among all phosphorus components.The application of bag-controlled slow-release fertilizer in red soil of eucalyptus plantation in southern China could promote the accumulation of phosphorus and increase the phosphorus activity.The mechanism of higher phosphorus use efficiency in bag-controlled slow-release fertilizer was mainly through the sustained phosphorus input and reducing phosphorus immobilization in soil by obstructing the contact of phosphorus with acid soil,to guarantee the phosphorus supply in tree growth process.展开更多
Intercropping of mulberry(Morus alba L.)and alfalfa(Medicago sativa L.)is a new forestry-grass compound model in China,which can provide high forage yields with high protein.Nitrogen application is one of the importan...Intercropping of mulberry(Morus alba L.)and alfalfa(Medicago sativa L.)is a new forestry-grass compound model in China,which can provide high forage yields with high protein.Nitrogen application is one of the important factors determining the production and quality of this system.To elucidate the advantages of intercropping and nitrogen application,we analyzed the changes of physicochemical properties,enzyme activities,and microbial communities in the rhizosphere soil.We used principal components analysis(PCA)and redundancy discriminators analysis to clarify the relationships among treatments and between treatments and environmental factors,respectively.The results showed that nitrogen application significantly increased pH value,available nitrogen content,soil water content(SWC),and urea(URE)activity in rhizosphere soil of monoculture mulberry.In contrast,intercropping and intercropping+N significantly decreased pH and SWC in mulberry treatments.Nitrogen,intercropping and intercropping+N sharply reduced soil organic matter content and SWC in alfalfa treatments.Nitrogen,intercropping,and intercropping+N increased the values of McIntosh diversity(U),Simpson diversity(D),and Shannon-Weaver diversity(H’)in mulberry treatments.However,PC A scatter plots showed clustering of monoculture mulberry with nitrogen(MNE)and intercropping mulberry without nitrogen(M0).Intercropping reduced both H’and D but nitrogen application showed no effect on diversity of microbial communities in alfalfa.There were obvious differences in using the six types of carbon sources between mulberry and alfalfa treatments.Nitrogen and intercropping increased the numbers of sole carbon substrate in mulberry treatments where the relative use rate exceeded 4%.While the numbers declined in alfalfa with nitrogen and intercropping.RDA indicated that URE was positive when intercropping mulberry was treated with nitrogen,but was negative in monoculture alfalfa treated with nitrogen.Soil pH and SWC were positive with mulberry treatments but were negative with alfalfa treatments.Intercropping with alfalfa benefited mulberry in the absence of nitrogen application.Intercropping with alfalfa and nitrogen application could improve the microbial community function and diversity in rhizosphere soil of mulberry.The microbial community in rhizosphere soil of mulberry and alfalfa is strategically complementary in terms of using carbon sources.展开更多
A complex number mode analysis approach is proposed for vibration reducing of structural flexible redundant manipulators by utilizing self motion. In the proposed approach, the self motion is evaluated to nullify the ...A complex number mode analysis approach is proposed for vibration reducing of structural flexible redundant manipulators by utilizing self motion. In the proposed approach, the self motion is evaluated to nullify the modal exciting force of flexural motion, and the approach can be freely used when the degree of freedom of flexural motion is much greater than the available degree of reundancy. The availability and effectiveness of the proposed approach are demonstrated through numerical simulation with a four link spatial robotic manipulator possessing an end flexible link.展开更多
Aims Beta diversity is the variation in species composition among sites in a geographic region.Beta diversity is a key concept for understanding the functioning of ecosystems,for the conservation of biodiversity and f...Aims Beta diversity is the variation in species composition among sites in a geographic region.Beta diversity is a key concept for understanding the functioning of ecosystems,for the conservation of biodiversity and for ecosystem management.The present report describes how to analyse beta diversity from community composition and associated environmental and spatial data tables.Methods Beta diversity can be studied by computing diversity indices for each site and testing hypotheses about the factors that may explain the variation among sites.Alternatively,one can carry out a direct analysis of the community composition data table over the study sites,as a function of sets of environmental and spatial variables.These analyses are carried out by the statistical method of partitioning the variation of the diversity indices or the community composition data table with respect to environmental and spatial variables.Variation partitioning is briefly described herein.Important findings Variation partitioning is a method of choice for the interpretation of beta diversity using tables of environmental and spatial variables.Beta diversity is an interesting‘currency’for ecologists to compare either different sampling areas or different ecological communities cooccurring in an area.Partitioning must be based upon unbiased estimates of the variation of the community composition data table that is explained by the various tables of explanatory variables.The adjusted coefficient of determination provides such an unbiased estimate in both multiple regression and canonical redundancy analysis.After partitioning,one can test the significance of the fractions of interest and plot maps of the fitted values corresponding to these fractions.展开更多
Aims studies of species distribution patterns traditionally have been conducted at a single scale,often overlooking species-environment relationships operating at finer or coarser scales.Testing diversity-related hypo...Aims studies of species distribution patterns traditionally have been conducted at a single scale,often overlooking species-environment relationships operating at finer or coarser scales.Testing diversity-related hypotheses at multiple scales requires a robust sampling design that is nested across scales.our chief motivation in this study was to quantify the contributions of different predictors of herbaceous species richness at a range of local scales.Methods Here,we develop a hierarchically nested sampling design that is balanced across scales,in order to study the role of several envi-ronmental factors in determining herbaceous species distribution at various scales simultaneously.We focus on the impact of woody vegetation,a relatively unexplored factor,as well as that of soil and topography.light detection and ranging(liDAR)imaging enabled precise characterization of the 3D structure of the woody vegetation,while acoustic spectrophotometry allowed a particularly high-resolution mapping of soil CaCo3 and organic matter contents.Important Findings We found that woody vegetation was the dominant explanatory variable at all three scales(10,100 and 1000 m2),accounting for more than 60%of the total explained variance.in addition,we found that the species richness-environment relationship was scale dependent.many studies that explicitly address the issue of scale do so by comparing local and regional scales.our results show that efforts to conserve plant communities should take into account scale dependence when analyzing species richness-environment relationships,even at much finer resolutions than local vs.regional.in addition,conserving heterogeneity in woody vegetation structure at multiple scales is a key to conserving diverse herbaceous communities.展开更多
The Yellow River Basin(YRB)occupies an important position in China’s socioeconomic development and ecological conservation efforts.Understanding the spatiotemporal characteristics of the relationships among multiple ...The Yellow River Basin(YRB)occupies an important position in China’s socioeconomic development and ecological conservation efforts.Understanding the spatiotemporal characteristics of the relationships among multiple ecosystem services(ESs)and their drivers is crucial for regional sustainable development and human-earth system coordination.This study simulated food production(FP),water yield(WY),net primary production(NPP),soil conservation(SC),and habitat quality(HQ)in the YRB from 2000 to 2020,and evaluated the spatial evolution and the relationship of ESs at the raster scale.Redundancy analysis was used to identify the impact of natural,socioeconomic,and landscape patterns on the relationship between ESs.The results demonstrated that the average HQ per unit area decreased by 18.10%,while SC,NPP,WY,and FP increased by 42.68%,47.63%,30.82%,and 67.10%,respectively,from 2000 to 2020.The relationship between ESs in the YRB was dominated by weak trade-offs and weak synergies at a temporal scale,with the trade-offs strengthened in the Upper Yellow River Basin(UYRB)and the Middle Yellow River Basin(MYRB),and synergies strengthened in the Lower Yellow River Basin(LYRB).At the spatial scale,the relationships between HQ and WY,HQ and SC,HQ and NPP,FP and SC,and FP and HQ were all dominated by trade-offs,while other ES pairs were mostly based on synergistic relationships.In the YRB,the relationships among ESs were mainly influenced by human disturbance,precipitation,and land-use and exploitation intensity.Specifically,the trade-offs among ESs in the UYRB were primarily affected by precipitation,and those in the MYRB and LYRB by human disturbance.The heterogeneity of the landscape could also effectively promote synergies among ESs.This study could provide insights into trade-offs and synergies among ESs and their driving forces and lay a foundation for ecological restoration and sustainable development of ESs in the YRB.展开更多
Aims Deserts are one of the ecosystems most sensitive to global climate change.However,there are few studies examining how changing abiotic and biotic factors under climate change will affect plant species diversity i...Aims Deserts are one of the ecosystems most sensitive to global climate change.However,there are few studies examining how changing abiotic and biotic factors under climate change will affect plant species diversity in the temperate deserts of Asia.This study aimed to:(i)characterize species distributions and diversity patterns in an Asian temperate desert;and(ii)to quantify the effects of spatial and environment variables on plant species diversity.Methods We surveyed 61 sites to examine the relationship between plant species diversity and several spatial/environmental variables in the Gurbantunggut Desert.Spatial and environmental variables were used to predict plant species diversity in separate multiple regression and ordination models.Variation in species responses to spatial and environmental conditions was partitioned by combining these variables in a redundancy analysis(RDA)and by creating multivariate regression trees(MRT).Important Findings We found 92 plant species across the 61 sites.Elevation and geographic location were the dominant environmental factors underlying variation in site species richness.A RDA indicated that 93%of the variance in the species–environment relationships was explained by altitude,latitude,longitude,precipitation and slope position.Precipitation and topographic heterogeneity,through their effects on water availability,were more important than soil chemistry in determining the distribution of species.MRT analyses categorized communities into four groups based on latitude,soil pH and elevation,explaining 42.3%of the standardized species variance.Soil pH strongly influenced community composition within homogeneous geographic areas.Our findings suggest that precipitation and topographic heterogeneity,rather than edaphic heterogeneity,are more closely correlated to the number of species and their distributions in the temperate desert.展开更多
Chiral pesticides account for 30% of pesticides. Pesticides are inevitably leached into the groundwater by runoff. At the watershed level, the distribution characteristics of enantiomers in sediments collected from th...Chiral pesticides account for 30% of pesticides. Pesticides are inevitably leached into the groundwater by runoff. At the watershed level, the distribution characteristics of enantiomers in sediments collected from the river network of an agricultural area near the middle and lower reaches of the Yangtze River were tested, and their potential correlations with the physicochemical properties and microbial communities of the sediments were analyzed. The sediment pollution was serious at sites 8 and 9, with their pollution source possibly being agricultural or industrial sewage. Moreover, there were higher cumulative contents of pesticide residues at sites 4, 8, and 9. Specifically, Cycloxaprid was the most detected chiral pesticide in the study area, followed by Dinotefuran and Diclofop-methyl. Additionally,Ethiprole and Difenoconazole had strong enantioselectivity in the study area. Interestingly,the enantiomers of some chiral pesticides, such as Tebuconazole, had completely different distributions at different sites. Pearson correlation analysis showed that sediment catalase and microbial biomass carbon were important factors for enantioselectivity of chiral pesticides. The effect of sediment physicochemical properties on enantioselective distribution was achieved by influencing the microorganisms in the sediment. Furthermore, the enantioselective distribution of Tebuconazole was closely related to the genus Arenimonas.Overall, the enantioselective distribution of most of the chiral pesticides was positively correlated with the prokaryotic microbial community. This study provides empirical support for agricultural non-point source pollution caused by chiral pesticides, and also lays a research foundation for exploring the factors that affect the fate of chiral pesticides in the environment.展开更多
The influences of technical factors on the catching efficiencies of gillnets are well understood,but less is known about the importance of environmental factors and how these might concurrently affect target-species c...The influences of technical factors on the catching efficiencies of gillnets are well understood,but less is known about the importance of environmental factors and how these might concurrently affect target-species condition.Here we address this deficit for two economically important southeast Asian cyprinids(Labiobarbus festivus and Osteochilus hasseltii)during a one-year study at a key fishing location in Lake Kenyir,Malaysia.Three gillnets(each 200 m long,2 m deep and comprising either 38-,51-,or 76-mm mesh)were deployed each month concurrent with sampling of benthic macroinvertebrates and various environmental parameters.Various multivariate analyses(detrended correspondence analysis,redundancy analysis and permutational multivariate analysis of variance)were used to explore potential relationships between the extrinsic variables(mesh size,sampling season,water quality and,based on known prey items,benthic macroinvertebrates)and gillnet catches and the biological condition(growth co-efficient and hepatosomatic index)of the target species.Catches of L.festivus(the most abundant species)were positively influenced by water turbidity without seasonal effects,while their biological condition was positively influenced by benthic macroinvertebrates(mostly Trichoptera)and the concentrations of DO and phosphate,and negatively influenced by water temperature.By comparison,seasonal influences on the catches and biology of O.hasseltii were somewhat size specific with positive and negative effects of the monsoon on small and large fish,respectively.The abundance of phytoplankton also positively affected the catches of O.hasseltii,while their biological condition was positively influenced by water temperature,but negatively influenced by water turbidity.Such species-specific differences were attributed to life histories,and although the more abundant L.festivus might be best sought during any period of turbidity,effort should be focused during the monsoon when individuals have optimal condition(and therefore better flesh quality).In contrast,larger O.hasseltii might be best sought during non-monsoon months concurrent with greater catches and optimal condition.Collecting similar data for other freshwater species both nationally and internationally might facilitate future efforts at fine-tuning gillnet fishing effort.展开更多
基金supported by the National Natural Science Foundation of China(42071102).
文摘The reconstruction of paleovegetation and paleoclimate requires an understanding of the relationships between surface pollen assemblages and modern vegetation and climate.Here,we analyzed the characteristics of surface pollen assemblages across different vegetation zones in the Tianshan Mountains.Using surface pollen analysis and vegetation sample surveys at 75 sites on the northern slopes of the Tianshan Mountains,we determined the correlation between the percentage of dominant pollen types and the corresponding vegetation cover.Redundancy analysis was used to investigate the relationships between surface pollen assemblages and environmental factors.Our results show that the Tianshan Mountains contain several distinct ecological regions,which can be divided into five main vegetation zones from low to high altitudes:mountain desert zone(Hutubi County(HTB):500-1300 m;Qitai County(QT):1000-1600 m),mountain steppe zone(HTB:1400-1600 m;QT:1650-1800 m),mountain forest zone(HTB:1650-2525 m;QT:1850-2450 m),subalpine meadow zone(HTB:2550-2600 m;QT:2500-2600 m),and alpine mat vegetation zone(HTB:2625-2700 m;QT:2625-2750 m).The surface pollen assemblages of different vegetation zones can accurately reflect the characteristics of the mountainous vegetation patterns on the northern slopes of the Tianshan Mountains when excluding the widespread occurrence of Chenopodiaceae,Artemisia,and Picea pollen.Both average annual precipitation(P_(ann))and annual average temperature(T_(ann))affect the distribution of surface pollen assemblages.Moreover,P_(ann) is the primary environmental factor affecting surface pollen assemblages in this region.A significant correlation exists between the pollen percentage and vegetation cover of Picea,Chenopodiaceae,Artemisia,and Asteraceae.Moreover,Picea,Chenopodiaceae,and Artemisia pollen are over-represented compared with their corresponding vegetation cover.The Asteraceae pollen percentage roughly reflects the distribution of a species within the local vegetation.These results have important implications for enhancing our understanding of the relationship between surface pollen assemblages and modern vegetation and climate.
基金the National Key Technology R&D Program of China(2018YFD0500206)the National Natural Science Foundation of China(31572209,31772395 and 31972943)the Foundation for Safety of Agricultural Products by Ministry of Agriculture and Rural Affairs,China(GJFP2019033)。
文摘Effects of the heavy metal copper(Cu), the metalloid arsenic(As), and the antibiotic oxytetracycline(OTC) on bacterial community structure and diversity during cow and pig manure composting were investigated. Eight treatments were applied, four to each manure type, namely cow manure with:(1) no additives(control),(2) addition of heavy metal and metalloid,(3) addition of OTC and(4) addition of OTC with heavy metal and metalloid;and pig manure with:(5) no additives(control),(6) addition of heavy metal and metalloid,(7) addition of OTC and(8) addition of OTC with heavy metal and metalloid. After 35 days of composting, according to the alpha diversity indices, the combination treatment(OTC with heavy metal and metalloid) in pig manure was less harmful to microbial diversity than the control or heavy metal and metalloid treatments. In cow manure, the treatment with heavy metal and metalloid was the most harmful to the microbial community, followed by the combination and OTC treatments. The OTC and combination treatments had negative effects on the relative abundance of microbes in cow manure composts. The dominant phyla in both manure composts included Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria. The microbial diversity relative abundance transformation was dependent on the composting time. Redundancy analysis(RDA) revealed that environmental parameters had the most influence on the bacterial communities. In conclusion, the composting process is the most sustainable technology for reducing heavy metal and metalloid impacts and antibiotic contamination in cow and pig manure. The physicochemical property variations in the manures had a significant effect on the microbial community during the composting process. This study provides an improved understanding of bacterial community composition and its changes during the composting process.
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.
基金Supported by the National Key Technology R&D Program of China(No.2014BAC09B02)the National Water Pollution Control and Management Technology Major Projects(No.2012ZX07101-002)the High-Level Scientific Research Foundation for the Introduction of Talent(No.E07016043)
文摘We characterized variations in bacterioplankton community composition(BCC) in mesocosms subject to three different treatments. Two groups contained fish(group one: Cyprinus carpio; group two: Hypophthalmichthys molitrix); and group three, the untreated mesocosm, was the control. Samples were taken seven times over a 49-d period, and BCC was analyzed by PCR-denaturing gradient gel electrophoresis(DGGE) and real-time quantitative PCR(q PCR). Results revealed that introduction of C. carpio and H. molitrix had a remarkable impact on the composition of bacterioplankton communities, and the BCC was significantly diff erent between each treatment. Sequencing of DGGE bands revealed that the bacterioplankton community in the different treatment groups was consistent at a taxonomic level, but differed in its abundance. H. molitrix promoted the richness of Alphaproteobacteria and Actinobacteria, while more bands affiliated to Cyanobacteria were detected in C. carpio mesocosms. The redundancy analysis(RDA) result demonstrated that the BCC was closely related to the bottom-up(total phosphorus, chlorophyll a, phytoplankton biomass) and top-down forces(biomass of copepods and cladocera) in C. carpio and control mesocosms, respectively. We found no evidence for top-down regulation of BCC by zooplankton in H. molitrix mesocosms, while grazing by protozoa(heterotrophic nanoflagellates, ciliates) became the major way to regulate BCC. Total bacterioplankton abundances were significantly higher in C. carpio mesocosms because of high nutrient concentration and suspended solids. Our study provided insights into the relationship between fish and bacterioplankton at species level, leading to a deep understanding of the function of the microbial loop and the aquatic ecosystem.
基金the National Key Research and Developmental Program of China(2017YFD0300502-2)。
文摘Tillage practices and organic amendment are strategies used worldwide to preserve the properties and fertility of soils.This study aimed to elucidate effects of 3-year field treatments of tillage practice and straw management on physical properties of Mollisols,root architecture and maize yield in northeast China.The experiment was conducted from 2015 to 2018 following a splitplot design of a randomized complete block with tillage practices[rotary tillage(R)and deep tillage(D)]as main plots and straw managements[straw returning(S),straw returning and organic fertilizer(M),straw removal(T)]as subplots.Soil samples at 0-15,15-30,30-50 cm depths and root samples at the seedling stage were collected.The results showed that DM treatment significantly improved soil moisture content at 10-50 cm soil depth and decreased soil compaction(P<0.05),which led to a better root architecture.Rotary tillage had a slower thermal conductivity but better thermal insulation performance,while deep tillage showed a higher daily temperature difference.Bulk density of topsoil was significantly lower in DS(1.16 g·cm^(-3))than in other treatments,but the soil permeability in DS(1.40 mm·min^(-1)in 0-15 soil depth and 1.45 mm·min-1in 15-30 cm soil depth)was the highest.At the maize seedling stage,DM had the highest root dry weight,root-shoot ratio and root length,while RM had the highest root volume,root furcation number and root tip number.The maize yield of three years in DM was 6.19%,5.21%and 15.72%higher than that in DS,DT and RM(P<0.01),respectively.Relative to RT and DT,a slight decrease(2.72%and 0.93%,respectively)in maize yield under RS and DS was observed,which could be alleviated by the addition of organic fertilizer.The correlation matrix indicated that kernel per ear number and 100-kernel weight were the dominant factors that affected maize yield.Redundancy analysis suggested that straw managements and tillage practices were significantly positively correlated with root-shoot ratio,root dry weight,maximum root length,the total root length and maize yield,but significantly negatively correlated with soil compaction,bulk density,soil moisture content and soil temperature.Among all the treatments,deep tillage with straw returning and the addition of organic fertilizer was recommended as a promising strategy in restoring soil productivity,promoting maize growth and increasing maize yield in Mollisols of northeast China and similar regions around the world.
基金This study was financially supported by the National Key R&D Program of China(2018YFC1704100 and 2018YFC1704101)Beijing Municipal Natural Science Foundation(7172131).
文摘Objective:Gastrointestinal heat retention syndrome(GHRS)is associated with lung-heat syndrome and is related to recurrent respiratory infection.Upper respiratory tract infection(URTI)lung heat syndrome is common in children.The study will explore the effect of GHRS on the structure and function of gut microbiota in children with URTI lung-heat syndrome.Methods:Participants were divided into both groups using the self-developed URTI scale and the“GHRS Diagnostic Scale$Pediatric Part”:GHRS-positive children(LS group)and GHRS-negative children(L group).General information,clinical symptoms,and stool were collected.We used 16S rRNA amplicon sequencing technology to determine the gene sequence of the V3eV4 region in feces and measure the gut microbiota of the both groups at the genus level.Results:A total of 23 children were included in the both groups.There were 12 cases in the LS group and 11 cases in the L group.There was no statistical difference between the both groups in age,gender,height,weight,and body mass index.The effective sequences shared by the both groups accounted for 85.66%of the total.In the gut microbiota,there was no difference in the a diversity and the b diversity between the both groups.Compared with the L group,the LS group had a significant increase in the relative abundance of the Ruminococcus gnavus group,Prevotella-9,Staphylococcus,and Actinomyces(P<.05).The functions of the both groups of microbiota primarily concentrate on metabolism,genetic information processing,and environmental information processing.The relative abundance of signaling molecules and interactions in the LS group were higher than that in the L group(P<.05).The redundancy analysis(RDA)showed that the URTI score had the greatest impact on the distribution of microbiota.Conclusion:GHRS may affect the development of URTI lung-heat syndrome by changing the relative abundances of gut microbiota.
基金Supported by Special Item of Basic Business Expenses of Guangxi Academy of Forestry Sciences(LINKE 202113)Forestry Science and Technology Promotion Demonstration Project of the Central Finance([2021]TG18)Special Fund Project for Innovation Driven Development in Guangxi(GUIKE AA17204087-11)。
文摘The insufficient supply of phosphorus is the main problem facing agriculture and forestry production in red soil region of southern China.To investigate whether applying bag-controlled slow-release fertilizer can improve the phosphorus availability and available phosphorus component content,with Gaofeng State-owned Eucalyptus Plantations Forest Farm in Guangxi red soil region as the research object,comparative test of different fertilizer types and fertilizer amount of bag-controlled slow-release fertilizer with conventional fertilization(G1),bag-controlled slow-release fertilizer with reducing fertilization(G2),traditional compound fertilizer(G3),basal fertilizer(G4),and no fertilization(G5)was designed.Soil phosphorus classification method was used to determine the content of phosphorus components in the soil,and redundancy analysis was used to study the effects of components on tree growth.The results showed that:compared with traditional fertilization,bag-controlled slow-release fertilizer significantly increased the contents of AP,Pi,Fe-P and other components in soil;the phosphorus activation coefficients of G2 and G1 were significantly higher than those of the other three treatments,and the order was G2>G1>G4>G5>G3;redundancy analysis showed that PAC and Fe-P had the most significant effect on plant growth among all phosphorus components.The application of bag-controlled slow-release fertilizer in red soil of eucalyptus plantation in southern China could promote the accumulation of phosphorus and increase the phosphorus activity.The mechanism of higher phosphorus use efficiency in bag-controlled slow-release fertilizer was mainly through the sustained phosphorus input and reducing phosphorus immobilization in soil by obstructing the contact of phosphorus with acid soil,to guarantee the phosphorus supply in tree growth process.
基金the Heilongjiang Province Science Foundation for Youths(Grant No.QC2016018)the National Natural Science Foundation of China(Grant No.31600508)+2 种基金the Fundamental Research Funds for the Central University(2572017CA21)the Application Technology Research and Development Projects of Heilongjiang Province(Grant No.WB13B104)the Science and Technology Project of Heilongjiang Farms&Land Reclamation Administration(Grant No.HNK135-01-056)。
文摘Intercropping of mulberry(Morus alba L.)and alfalfa(Medicago sativa L.)is a new forestry-grass compound model in China,which can provide high forage yields with high protein.Nitrogen application is one of the important factors determining the production and quality of this system.To elucidate the advantages of intercropping and nitrogen application,we analyzed the changes of physicochemical properties,enzyme activities,and microbial communities in the rhizosphere soil.We used principal components analysis(PCA)and redundancy discriminators analysis to clarify the relationships among treatments and between treatments and environmental factors,respectively.The results showed that nitrogen application significantly increased pH value,available nitrogen content,soil water content(SWC),and urea(URE)activity in rhizosphere soil of monoculture mulberry.In contrast,intercropping and intercropping+N significantly decreased pH and SWC in mulberry treatments.Nitrogen,intercropping and intercropping+N sharply reduced soil organic matter content and SWC in alfalfa treatments.Nitrogen,intercropping,and intercropping+N increased the values of McIntosh diversity(U),Simpson diversity(D),and Shannon-Weaver diversity(H’)in mulberry treatments.However,PC A scatter plots showed clustering of monoculture mulberry with nitrogen(MNE)and intercropping mulberry without nitrogen(M0).Intercropping reduced both H’and D but nitrogen application showed no effect on diversity of microbial communities in alfalfa.There were obvious differences in using the six types of carbon sources between mulberry and alfalfa treatments.Nitrogen and intercropping increased the numbers of sole carbon substrate in mulberry treatments where the relative use rate exceeded 4%.While the numbers declined in alfalfa with nitrogen and intercropping.RDA indicated that URE was positive when intercropping mulberry was treated with nitrogen,but was negative in monoculture alfalfa treated with nitrogen.Soil pH and SWC were positive with mulberry treatments but were negative with alfalfa treatments.Intercropping with alfalfa benefited mulberry in the absence of nitrogen application.Intercropping with alfalfa and nitrogen application could improve the microbial community function and diversity in rhizosphere soil of mulberry.The microbial community in rhizosphere soil of mulberry and alfalfa is strategically complementary in terms of using carbon sources.
文摘A complex number mode analysis approach is proposed for vibration reducing of structural flexible redundant manipulators by utilizing self motion. In the proposed approach, the self motion is evaluated to nullify the modal exciting force of flexural motion, and the approach can be freely used when the degree of freedom of flexural motion is much greater than the available degree of reundancy. The availability and effectiveness of the proposed approach are demonstrated through numerical simulation with a four link spatial robotic manipulator possessing an end flexible link.
基金Funding was provided by Natural Sciences and Engineering Research Council of Canada(NSERC)grant no.OGP0007738 to P.L.
文摘Aims Beta diversity is the variation in species composition among sites in a geographic region.Beta diversity is a key concept for understanding the functioning of ecosystems,for the conservation of biodiversity and for ecosystem management.The present report describes how to analyse beta diversity from community composition and associated environmental and spatial data tables.Methods Beta diversity can be studied by computing diversity indices for each site and testing hypotheses about the factors that may explain the variation among sites.Alternatively,one can carry out a direct analysis of the community composition data table over the study sites,as a function of sets of environmental and spatial variables.These analyses are carried out by the statistical method of partitioning the variation of the diversity indices or the community composition data table with respect to environmental and spatial variables.Variation partitioning is briefly described herein.Important findings Variation partitioning is a method of choice for the interpretation of beta diversity using tables of environmental and spatial variables.Beta diversity is an interesting‘currency’for ecologists to compare either different sampling areas or different ecological communities cooccurring in an area.Partitioning must be based upon unbiased estimates of the variation of the community composition data table that is explained by the various tables of explanatory variables.The adjusted coefficient of determination provides such an unbiased estimate in both multiple regression and canonical redundancy analysis.After partitioning,one can test the significance of the fractions of interest and plot maps of the fitted values corresponding to these fractions.
文摘Aims studies of species distribution patterns traditionally have been conducted at a single scale,often overlooking species-environment relationships operating at finer or coarser scales.Testing diversity-related hypotheses at multiple scales requires a robust sampling design that is nested across scales.our chief motivation in this study was to quantify the contributions of different predictors of herbaceous species richness at a range of local scales.Methods Here,we develop a hierarchically nested sampling design that is balanced across scales,in order to study the role of several envi-ronmental factors in determining herbaceous species distribution at various scales simultaneously.We focus on the impact of woody vegetation,a relatively unexplored factor,as well as that of soil and topography.light detection and ranging(liDAR)imaging enabled precise characterization of the 3D structure of the woody vegetation,while acoustic spectrophotometry allowed a particularly high-resolution mapping of soil CaCo3 and organic matter contents.Important Findings We found that woody vegetation was the dominant explanatory variable at all three scales(10,100 and 1000 m2),accounting for more than 60%of the total explained variance.in addition,we found that the species richness-environment relationship was scale dependent.many studies that explicitly address the issue of scale do so by comparing local and regional scales.our results show that efforts to conserve plant communities should take into account scale dependence when analyzing species richness-environment relationships,even at much finer resolutions than local vs.regional.in addition,conserving heterogeneity in woody vegetation structure at multiple scales is a key to conserving diverse herbaceous communities.
基金National Natural Science Foundation of China,No.41931293National Natural Science Foundation of China,No.42171208The Strategic Priority Research Program of the Chinese Academy of Sciences,No.XDA23070302。
文摘The Yellow River Basin(YRB)occupies an important position in China’s socioeconomic development and ecological conservation efforts.Understanding the spatiotemporal characteristics of the relationships among multiple ecosystem services(ESs)and their drivers is crucial for regional sustainable development and human-earth system coordination.This study simulated food production(FP),water yield(WY),net primary production(NPP),soil conservation(SC),and habitat quality(HQ)in the YRB from 2000 to 2020,and evaluated the spatial evolution and the relationship of ESs at the raster scale.Redundancy analysis was used to identify the impact of natural,socioeconomic,and landscape patterns on the relationship between ESs.The results demonstrated that the average HQ per unit area decreased by 18.10%,while SC,NPP,WY,and FP increased by 42.68%,47.63%,30.82%,and 67.10%,respectively,from 2000 to 2020.The relationship between ESs in the YRB was dominated by weak trade-offs and weak synergies at a temporal scale,with the trade-offs strengthened in the Upper Yellow River Basin(UYRB)and the Middle Yellow River Basin(MYRB),and synergies strengthened in the Lower Yellow River Basin(LYRB).At the spatial scale,the relationships between HQ and WY,HQ and SC,HQ and NPP,FP and SC,and FP and HQ were all dominated by trade-offs,while other ES pairs were mostly based on synergistic relationships.In the YRB,the relationships among ESs were mainly influenced by human disturbance,precipitation,and land-use and exploitation intensity.Specifically,the trade-offs among ESs in the UYRB were primarily affected by precipitation,and those in the MYRB and LYRB by human disturbance.The heterogeneity of the landscape could also effectively promote synergies among ESs.This study could provide insights into trade-offs and synergies among ESs and their driving forces and lay a foundation for ecological restoration and sustainable development of ESs in the YRB.
基金Natural Science Foundation of ChinaXinjiang(U1130304)the National Science Foundation of China(41061004 and 31260099).
文摘Aims Deserts are one of the ecosystems most sensitive to global climate change.However,there are few studies examining how changing abiotic and biotic factors under climate change will affect plant species diversity in the temperate deserts of Asia.This study aimed to:(i)characterize species distributions and diversity patterns in an Asian temperate desert;and(ii)to quantify the effects of spatial and environment variables on plant species diversity.Methods We surveyed 61 sites to examine the relationship between plant species diversity and several spatial/environmental variables in the Gurbantunggut Desert.Spatial and environmental variables were used to predict plant species diversity in separate multiple regression and ordination models.Variation in species responses to spatial and environmental conditions was partitioned by combining these variables in a redundancy analysis(RDA)and by creating multivariate regression trees(MRT).Important Findings We found 92 plant species across the 61 sites.Elevation and geographic location were the dominant environmental factors underlying variation in site species richness.A RDA indicated that 93%of the variance in the species–environment relationships was explained by altitude,latitude,longitude,precipitation and slope position.Precipitation and topographic heterogeneity,through their effects on water availability,were more important than soil chemistry in determining the distribution of species.MRT analyses categorized communities into four groups based on latitude,soil pH and elevation,explaining 42.3%of the standardized species variance.Soil pH strongly influenced community composition within homogeneous geographic areas.Our findings suggest that precipitation and topographic heterogeneity,rather than edaphic heterogeneity,are more closely correlated to the number of species and their distributions in the temperate desert.
基金supported by the Fundamental Research Funds for the Central Universities (No. B210201007)。
文摘Chiral pesticides account for 30% of pesticides. Pesticides are inevitably leached into the groundwater by runoff. At the watershed level, the distribution characteristics of enantiomers in sediments collected from the river network of an agricultural area near the middle and lower reaches of the Yangtze River were tested, and their potential correlations with the physicochemical properties and microbial communities of the sediments were analyzed. The sediment pollution was serious at sites 8 and 9, with their pollution source possibly being agricultural or industrial sewage. Moreover, there were higher cumulative contents of pesticide residues at sites 4, 8, and 9. Specifically, Cycloxaprid was the most detected chiral pesticide in the study area, followed by Dinotefuran and Diclofop-methyl. Additionally,Ethiprole and Difenoconazole had strong enantioselectivity in the study area. Interestingly,the enantiomers of some chiral pesticides, such as Tebuconazole, had completely different distributions at different sites. Pearson correlation analysis showed that sediment catalase and microbial biomass carbon were important factors for enantioselectivity of chiral pesticides. The effect of sediment physicochemical properties on enantioselective distribution was achieved by influencing the microorganisms in the sediment. Furthermore, the enantioselective distribution of Tebuconazole was closely related to the genus Arenimonas.Overall, the enantioselective distribution of most of the chiral pesticides was positively correlated with the prokaryotic microbial community. This study provides empirical support for agricultural non-point source pollution caused by chiral pesticides, and also lays a research foundation for exploring the factors that affect the fate of chiral pesticides in the environment.
基金the International Islamic University Malaysia,Malaysia for providing financial support through P-RIGS18-032-0032 project.
文摘The influences of technical factors on the catching efficiencies of gillnets are well understood,but less is known about the importance of environmental factors and how these might concurrently affect target-species condition.Here we address this deficit for two economically important southeast Asian cyprinids(Labiobarbus festivus and Osteochilus hasseltii)during a one-year study at a key fishing location in Lake Kenyir,Malaysia.Three gillnets(each 200 m long,2 m deep and comprising either 38-,51-,or 76-mm mesh)were deployed each month concurrent with sampling of benthic macroinvertebrates and various environmental parameters.Various multivariate analyses(detrended correspondence analysis,redundancy analysis and permutational multivariate analysis of variance)were used to explore potential relationships between the extrinsic variables(mesh size,sampling season,water quality and,based on known prey items,benthic macroinvertebrates)and gillnet catches and the biological condition(growth co-efficient and hepatosomatic index)of the target species.Catches of L.festivus(the most abundant species)were positively influenced by water turbidity without seasonal effects,while their biological condition was positively influenced by benthic macroinvertebrates(mostly Trichoptera)and the concentrations of DO and phosphate,and negatively influenced by water temperature.By comparison,seasonal influences on the catches and biology of O.hasseltii were somewhat size specific with positive and negative effects of the monsoon on small and large fish,respectively.The abundance of phytoplankton also positively affected the catches of O.hasseltii,while their biological condition was positively influenced by water temperature,but negatively influenced by water turbidity.Such species-specific differences were attributed to life histories,and although the more abundant L.festivus might be best sought during any period of turbidity,effort should be focused during the monsoon when individuals have optimal condition(and therefore better flesh quality).In contrast,larger O.hasseltii might be best sought during non-monsoon months concurrent with greater catches and optimal condition.Collecting similar data for other freshwater species both nationally and internationally might facilitate future efforts at fine-tuning gillnet fishing effort.
