Zooplankton community structure along a pollution gradient at fine geographical scales in river ecosystems: The importance of species sorting over dispersal

The release of anthropogenic pollution into freshwater ecosystems has largely transformed biodiversity and its geographical distribution patterns globally. However, for many communities including ecologically crucial ones such as zooplankton, it is largely unknown how different communities respond to environmental pollution. Collectively, dispersal and species sorting are two competing processes in determining the structure and geographical distribution of zooplankton communities in running water ecosystems such as rivers. At fine geographical scales, dispersal is usually considered as the dominant factor; however, the relative role of species sorting has not been evaluated well, mainly because significant environmental gradients rarely exist along continuously flowing rivers. The Chaobai River in northern China represents a rare system, where a significant environmental gradient exists at fine scales. Here, we employed high‐throughput sequencing to characterize complex zooplankton communities collected from the Chaobai River, and tested the relative roles of dispersal and species sorting in determining zooplankton community structure along the pollution gradient. Our results showed distinct patterns of zooplankton communities along the environmental gradient, and chemical pollutant‐related factors such as total phosphorus and chlorophyll‐a were identified as the major drivers for the observed patterns. Further partial redundancy analyses showed that species sorting overrode the effect of dispersal to shape local zooplankton community structure. Thus, our results reject the dispersal hypothesis and support the concept that species sorting caused by local pollution can largely determine the zooplankton community structure when significant environmental gradients exist at fine geographical scales in highly polluted running water ecosystems.     

Geographical distribution of zooplankton biodiversity in highly polluted running water ecosystems: Validation of fine‐scale species sorting hypothesis

Dispersal, rather than species sorting, is widely recognized as the dominant driver for determining meta‐community structure at fine geographical scales in running water ecosystems. However, this view has been challenged by a recently proposed “fine‐scale species sorting hypothesis,” where community structure can be largely determined by an environmental gradient formed by local pollution at fine scales. Here, we tested this hypothesis by studying community composition and geographical distribution of metazoan zooplankton in a heavily polluted river—the North Canal River in the Haihe River Basin, China. Analysis of similarity (ANOSIM) showed that the community composition of metazoan zooplankton differed significantly (p = .001) along the environmental gradient. Ammonium (NH₄‐N) was the leading factor responsible for changes in zooplankton community structure and geographical distribution, followed by total dissolved solid (TDS), Na, dissolved oxygen (DO) and temperature (T). Variation partitioning revealed a larger contribution of environmental variables (21.6%) than spatial variables (1.1%) to the total explained variation of zooplankton communities. Our results support that species sorting, rather than dispersal, played a key role in structuring communities. Threshold Indicator Taxa ANalysis (TITAN) also revealed significant change points at both taxon and community levels along the gradient of NH₄‐N, providing further support for the influence of environmental variables on zooplankton communities. Collectively, we validate the fine‐scale species sorting hypothesis when an environmental gradient exists in running water ecosystems at fine geographical scales. However, future studies on interactions between pollutants and zooplankton communities are still needed to better understand mechanisms responsible for the meta‐community dynamics.     

Seasonal strengths of the abiotic and biotic drivers of a zooplankton community

相似文献   

基于宏基因组的保安湖浮游动物多样性研究

研究于2019年春、夏、秋、冬四季对保安湖进行了水样采集, 基于宏基因组测序, 在优化物种鉴定和丰度计算方法的基础上, 考察了保安湖浮游动物的多样性、群落结构及其影响因素。共鉴定到浮游动物OTU 374种, 其中原生动物282个; 枝角类45个; 桡足类26个; 轮虫21个。从季节来看, 夏、秋季保安湖的浮游动物多样性高; 从湖区来看, 肖四海和主湖区浮游动物多样性高。季节因素对保安湖浮游动物群落结构的影响高于湖区影响。保安湖营养状态为中营养型, 水体温度、叶绿素a是影响保安湖浮游动物群落结构的主要环境因子, 不同类群与环境因子相关性不同, 总体可分为5类。其中原生动物优势类群为混合营养的纤毛虫和丝足虫, 同硝氮、化学需氧量、温度有明显的相关性, 而枝角类和桡足类同环境因子的关系较为相似, 与溶氧、叶绿素a、正磷酸盐存在明显相关。研究利用宏基因组方法对保安湖浮游动物多样性开展了研究, 为从浮游动物这一角度来理解保安湖这一江湖阻隔型湖泊的生物多样性的变化提供了支撑。     

Population attenuation in zooplankton communities during transoceanic transfer in ballast water

Successful biological invasion requires introduction of a viable population of a nonindigenous species (NIS). Rarely have ecologists assessed changes in populations while entrained in invasion pathways. Here, we investigate how zooplankton communities resident in ballast water change during transoceanic voyages. We used next‐generation sequencing technology to sequence a nuclear small subunit ribosomal DNA fragment of zooplankton from ballast water during initial, middle, and final segments as a vessel transited between Canada and Brazil. Operational taxonomic unit (OTU) diversity decreased as voyage duration increased, indicating loss of community‐based genetic diversity and development of bottlenecks for zooplankton taxa prior to discharge of ballast water. On average, we observed 47, 26, and 24 OTUs in initial, middle, and final samples, respectively. Moreover, a comparison of genetic diversity within taxa indicated likely attenuation of OTUs in final relative to initial samples. Abundance of the most common taxa (copepods) declined in all final relative to initial samples. Some taxa (e.g., Copepoda) were represented by a high number of OTUs throughout the voyage, and thus had a high level of intraspecific genetic variation. It is not clear whether genotypes that were most successful in surviving transit in ballast water will be the most successful upon introduction to novel environments. This study highlights that population bottlenecks may be common prior to introduction of NIS to new ecosystems.     

Impacts of a Small Dam on Riverine Zooplankton

In order to explore the temporal impacts of a small dam on riverine zooplankton, monthly samples were conducted from November 2005 to June 2006 in a reach of Xiangxi River, China, which is affected by a small hydropower plant. A total of 56 taxa of zooplankton were recorded during the study and rotifers were the most abundant group, accounting for 97% of total taxa, while the others were copepod nauplii and copepod adults. This study indicated that: (1) the small dam in the Xiangxi River study area created distinct physical and ecological conditions relative to free‐flowing lotic reaches despite the constrained channel and small size of the dam; (2) the existence of the plant's small dam had a significant effect on the zooplankton community. In long periods of drought or dry seasons the effect of the dam on potamoplankton was more pronounced (e.g., November, February, March, and May). But the downfall or the connectivity of channel appeared to decrease the effect of small hydropower plants on riverine zooplankton (e.g., April). The present observation underscores the need for additional studies that provide more basic data on riverine zooplankton communities and quantify ecological responses to dam construction over longer time spans. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Climate shifts the interaction web of a marine plankton community

Climatic effects in the ocean at the community level are poorly described, yet accurate predictions about ecosystem responses to changing environmental conditions rely on understanding biotic responses in a food‐web context to support knowledge about direct biotic responses to the physical environment. Here we conduct time‐series analyses with multivariate autoregressive (MAR) models of marine zooplankton abundance in the Northern California Current from 1996 to 2009 to determine the influence of climate variables on zooplankton community interactions. Autoregressive models showed different community interactions during warm vs. cool ocean climate conditions. Negative ecological interactions among zooplankton groups characterized the major warm phase during the time series, whereas during the major cool phase, ocean transport largely structured zooplankton communities. Local environmental conditions (sea temperature) and large‐scale climate indices (El Niño/Southern Oscillation) were associated with changes in zooplankton abundance across the full time series. Secondary environmental correlates of zooplankton abundance varied with ocean climate phase, with most support during the warm phase for upwelling as a covariate, and most support during the cool phase for salinity. Through simultaneous quantitation of community interactions and environmental covariates, we show that marine zooplankton community structure varies with climate, suggesting that predictions about ecosystem responses to future climate scenarios in the Northern California Current should include potential changes to the base of the pelagic food.     

香溪河流域梯级水库底栖动物群落比较

对香溪河流域3座梯级水库（古洞口一级水库、古洞口二级水库和三峡水库香溪河库湾）的底栖动物进行了比较生态学研究。运用主成分分析（PCA）对梯级水库的水质进行研究,表明沿着水库的梯度水质逐渐恶化。运用非度量多维标度法（NMS）对梯级水库的底栖动物群落结构进行相似性比较,表明选择水库湖泊区的样点进行梯级水库底栖动物生态学研究具有典型代表性。在物种组成和密度方面,古洞口一级水库和香溪河库湾都是寡毛类占优势,古洞口二级水库是摇蚊幼虫占优势。但3个水库都是耐污种占优势。采用典型对应分析（CCA）解析底栖动物群落结构与环境因子的关系,显示3个水库群落结构的差异主要由浊度造成。用TOC／Turb来表征有机物对浊度的贡献,结果显示古洞口二级水库有机物对浊度的贡献相对较小,因而表明泥沙等无机物对浊度的贡献相对较大。     

Seasonal zooplankton dynamics in main channel and backwater habitats of the Upper Mississippi River

This study used stratified random sampling to examine the spatial and temporal distribution of zooplankton communities in a large floodplain river (Mississippi River, USA). Potential mechanisms controlling zooplankton abundance and community structure were considered. Main channel and backwater habitats included in this study differed between a turbid upper pool reach where aquatic macrophytes were sparse and a lower pool reach which was considerably less turbid and had extensive aquatic macrophyte coverage. Samples were collected monthly during the summer over a 2-year period and multivariate analysis was used to examine the spatial and temporal distribution of zooplankton. Significant differences were found in zooplankton density and community composition among habitats and reaches within the pool. Rotifers were the dominant taxa and seasonality was pronounced, with peak densities often occurring in late-spring. Community structure varied by habitat and reach, which suggests that water quality, physical habitat characteristics, presence of aquatic macrophytes, and zooplankton sources can all influence the zooplankton communities of the Upper Mississippi River. Characterization of the zooplankton communities provides a basis for understanding changes in the river ecosystem and examination of zooplankton communities among habitats provides insight into the mechanisms affecting zooplankton dynamics.     

Biogeographical patterns of freshwater micro‐ and macroorganisms: a comparison between phytoplankton,zooplankton and fish in the eastern Mediterranean

Aim We investigated the biogeographical patterns of phytoplankton, zooplankton and fish in freshwater ecosystems. We tested whether spatial distance or environmental heterogeneity act as potential factors controlling community composition. Location Northern and central Greece, eastern Mediterranean. Method Data on 310 phytoplankton, 72 zooplankton and 37 fish species were collected from seven freshwater systems. Species occurrence data were used to generate similarity matrices describing community composition. We performed Mantel tests to compare spatial patterns in community composition of phytoplankton, zooplankton and fish. Next, we examined the correlation between geographical distance and the degree of similarity in community composition. The analysis was repeated for different taxonomic, trophic and size‐based groups of the microorganisms studied. We assessed different environmental variables (topographic and limnological) as predictors of community composition. Results Phytoplankton community composition showed a strong positive correlation with environmental heterogeneity but was not correlated with the geographical distance between systems. Zooplankton community composition was unrelated to geographical distance and was only weakly correlated with environmental variables. In contrast, fish community similarity decayed significantly with distance. We found no relationship along all pairwise comparisons of the compositional matrices of the three groups. The pairwise comparisons of the different taxonomic, trophic and size‐based groups of the microorganism communities studied were in accordance with the results for the entire microorganism community. Main conclusions Our results support the proposition that the biogeography of microorganisms does not demonstrate a distance–decay pattern and further suggest that, in reality, the drivers of distribution depend on the specific community examined. In contrast, the biogeography of macroorganisms was affected by geographical distance. These differences reflect the dispersal abilities of the different organisms. The microorganisms exhibit passive dispersal through the air, with local environmental conditions structuring their community composition. On the other hand, for macroorganisms such as fish, the terrestrial environment could pose barriers to their dispersal; with fish structuring distinctive communities over greater distances. Overall, we suggest that the biogeography of freshwater phytoplankton and zooplankton reflects contemporary environmental conditions, while the biogeographical patterns for fish inhabiting the same systems are related to factors affecting their dispersal ability.     

Seasonal pattern of zooplankton communities and their environmental response in subtropical maritime channels systems in the Bay of Bengal,Bangladesh

Zooplankton are a primary component of aquatic food chain and play an important role in the functioning of aquatic food webs. Seasonal variation in community structures of zooplankton and potential environmental drivers were studied, during a 1-year cycle (summer 2015 – spring 2016) in subtropical maritime channels systems in the Bay of Bengal, coastal waters in Bangladesh. A total of 32 species representing 25 families, 13 orders and 15 taxonomic groups were identified. Of these species, 23 distributed in all four season of which 8 were dominant species with high contributions of the total communities. Species number was peaked in autumn and fell in summer while maximum abundance was in the winter and minimum in summer. Multivariate analyses showed that there was a clear seasonal shift in zooplankton community structures in relation with environmental conditions. Species diversity and evenness peaked in summer while the high value of species richness was found in autumn. Multivariate correlation (RELATE) and BIO-ENV analysis demonstrated that seasonal variation in community patterns was significantly correlated with temporal shift of environmental conditions and that variation mainly driven by water transparency, salinity, DO, TSS and nutrients. Thus, this finding implies that the zooplankton community represented a clear seasonal shift shaped by environmental drivers in subtropical channels systems.     

Patterns in the Composition of Microbial Communities from a Subtropical River: Effects of Environmental,Spatial and Temporal Factors

Microbes are key components of aquatic ecosystems and play crucial roles in global biogeochemical cycles. However, the spatiotemporal dynamics of planktonic microbial community composition in riverine ecosystems are still poorly understood. In this study, we used denaturing gradient gel electrophoresis of PCR-amplified 16S and 18S rRNA gene fragments and multivariate statistical methods to explore the spatiotemporal patterns and driving factors of planktonic bacterial and microbial eukaryotic communities in the subtropical Jiulong River, southeast China. Both bacterial and microbial eukaryotic communities varied significantly in time and were spatially structured according to upper stream, middle-lower stream and estuary. Among all the environmental factors measured, water temperature, conductivity, PO₄-P and TN/TP were best related to the spatiotemporal distribution of bacterial community, while water temperature, conductivity, NO_x-N and transparency were closest related to the variation of eukaryotic community. Variation partitioning, based on partial RDA, revealed that environmental factors played the most important roles in structuring the microbial assemblages by explaining 11.3% of bacterial variation and 17.5% of eukaryotic variation. However, pure spatial factors (6.5% for bacteria and 9.6% for eukaryotes) and temporal factors (3.3% for bacteria and 5.5% for eukaryotes) also explained some variation in microbial distribution, thus inherent spatial and temporal variation of microbial assemblages should be considered when assessing the impact of environmental factors on microbial communities.     

Changes and drivers of zooplankton diversity patterns in the middle reach of Yangtze River floodplain lakes,China

Anthropogenic habitat alteration interferes the natural aquatic habitats and the system''s hydrodynamics in the Yangtze River floodplain lakes, resulting in a serious decline in freshwater biodiversity. Zooplankton communities possess major position in freshwater ecosystems, which play essential parts in maintaining biological balance of freshwater habitats. Knowledge of processes and mechanisms for affecting variations in abundance, biomass, and diversity of zooplankton is important for maintaining biological balance of freshwater ecosystems. Here, we analyzed that the temporal and spatial changes in the structure of zooplankton community and their temporal and spatial variations respond to changes in environmental factors in the middle reach of Yangtze River floodplain lakes. The results showed that zooplankton samples were classified into 128 species, and Rotifera was the most common taxa. Significant seasonal differences were found among the abundance and diversity of zooplankton. Similarly, we also found significant seasonal differences among the biomass of zooplankton functional groups. The spatial turnover component was the main contributor to the β diversity pattern, which indicated that study areas should establish habitat restoration areas to restore regional biodiversity. The NMDS plot showed that the structure of zooplankton community exhibited significant seasonal changes, where the community structure was correlated with pH, water temperature, water depth, salinity, total nitrogen, chlorophyll‐a, and total phosphorus based on RDA. This study highlights that it is very important to ensure the floodplain ecosystem''s original state of functionality for maintaining the regional diversity of the ecosystem as a whole.     

Damming interacts with the flood pulse to alter zooplankton communities in an Amazonian river

相似文献   

pH Influences the Importance of Niche-Related and Neutral Processes in Lacustrine Bacterioplankton Assembly

pH is an important factor that shapes the structure of bacterial communities. However, we have very limited information about the patterns and processes by which overall bacterioplankton communities assemble across wide pH gradients in natural freshwater lakes. Here, we used pyrosequencing to analyze the bacterioplankton communities in 25 discrete freshwater lakes in Denmark with pH levels ranging from 3.8 to 8.8. We found that pH was the key factor impacting lacustrine bacterioplankton community assembly. More acidic lakes imposed stronger environmental filtering, which decreased the richness and evenness of bacterioplankton operational taxonomic units (OTUs) and largely shifted community composition. Although environmental filtering was determined to be the most important determinant of bacterioplankton community assembly, the importance of neutral assembly processes must also be considered, notably in acidic lakes, where the species (OTU) diversity was low. We observed that the strong effect of environmental filtering in more acidic lakes was weakened by the enhanced relative importance of neutral community assembly, and bacterioplankton communities tended to be less phylogenetically clustered in more acidic lakes. In summary, we propose that pH is a major environmental determinant in freshwater lakes, regulating the relative importance and interplay between niche-related and neutral processes and shaping the patterns of freshwater lake bacterioplankton biodiversity.     

Environmental and spatial filters of zooplankton metacommunities in shallow pools in high‐elevation peatlands in the tropical Andes

相似文献   

松花江流域大型底栖动物群落结构与水质评价

【目的】松花江流域是中国最早的工业基地之一,其水生态环境遭到严重破坏,环境保护工作面临巨大挑战。开展松花江流域水质评价及典型生物类群多样性状况调查,可为松花江流域生态系统的保护和修复提供依据。【方法】于2016年7月调查整个松花江流域近岸的大型底栖动物群落组成和测定水质理化指标,开展其水质理化特征评价和生物指数评价,并探讨底栖动物群落分布与水环境因子间的关系。【结果】理化指标评价结果显示,南源松花江水质状况最差,处于中度污染;北源松花江处于轻度污染;梧桐河水质最好,处于良好状态。松花江流域3个河段的底栖动物群落结构存在空间差异性。另外,梧桐河的物种多样性最高,北源松花江次之,南源松花江最低。溶解氧和营养元素K的浓度是驱动底栖动物群落组成发生显著性差异的主要环境因子。生物指数评价结果显示,3个河段水质均处于轻度污染状态。【结论】松花江流域水质处于轻度到中度污染状态。有机污染是松花江流域面临的主要水质环境问题,对松花江流域底栖动物群落结构产生了显著影响。因此,控制有机质的输入是维持松花江流域水生态系统平衡的重要举措之一。     

Bacterial Community Succession in Natural River Biofilm Assemblages

Temporal bacterial community changes in river biofilms were studied using 16S rRNA gene-based polymerase chain reaction–denaturing gradient gel electrophoresis (DGGE) followed by sequence analysis. Naturally occurring biofilms were sampled in 2001 during an undisturbed 7-month low-water period in the River Garonne (SW France). During the sampling period epilithic biomass exhibited a particular pattern: two 3-month periods of accumulation that resulted in two peaks in summer and fall, each at about 25 g ash-free dry mass per square meter. Bacterial community DGGE profiles differed between the summer and fall biomass peaks and shared only 30% common operational taxonomic units (OTUs), suggesting the influence of seasonal factors on these communities. During the second biomass accrual phase, bacterial richness and the appearance of new OTUs fitted a conceptual model of bacterial biofilm succession. During succession, five OTUs (corresponding to Dechloromonas sp., Nitrospira sp., and three different Spirosoma spp.) exhibited particular patterns and were present only during clearly defined successional stages, suggesting differences in life-history strategies for epilithic bacteria. Co-inertia analysis of DGGE banding patterns and physical–chemical data showed a significant relationship between community structure and environmental conditions suggesting that bacterial communities were mainly influenced by seasonal changes (temperature, light) and hydrodynamic stability. Within the periods of stability, analysis of environmental variables and community patterns showed the dominant influence of time and maturation on bacterial community structure. Thus, succession in these naturally occurring epilithic biofilm assemblages appears to occur through a combination of allogenic (seasonal) and autogenic changes.     

Environmental factors influencing zooplankton species composition of lakes in north-central Ontario,Canada

To assess the relative importance of lake chemistry, morphometry and zoogeography on limnetic zooplankton, we collected zooplankton, water, and morphometric data from 132 headwater Canadian Shield lakes in 6 regions across north-central Ontario. A subset of these lakes (n = 52) were fished with gill nets. We clustered lakes based on their zooplankton species composition (presence/absence). Discriminant analysis was employed to determine how well lake characteristics could predict zooplankton community types. Correct classification of zooplankton communities for three models ranged from 72 to 91%. Lake size, lake location, and buffering capacity were ranked as the most important factors separating lake groups. Fish abundance (CPUE) was not significant in distinguishing between zooplankton communities. Though the range of lake sizes was limited (1–110 ha), larger lakes tended to support more species. Lake location (zoogeography) also influenced species composition patterns. Although Algoma lakes tended to be larger (\-x = 18.0 ha, other lakes \-x = 2.5 ha), they supported relatively depauperate zooplankton communities. Buffering capacity was ranked third in the discriminant analysis models, but pH and alkalinity were not significantly different between lake groups.     

Benthic diatom communities in boreal streams: community structure in relation to environmental and spatial gradients

An important goal for community ecology is the characterization and prediction of changes in community patterns along environmental gradients. We aimed to identify the major environmental correlates of diatom distribution patterns in boreal running waters. We classified 197 stream sites based on their diatom flora. Direct ordination methods were then used to identify the key environmental determinants of this diatom-based stream typology. Finally, we tested whether a regional classification scheme based on terrestrial landscapes (ecoregions) provides a reasonable framework for a regional grouping of streams based on their diatom flora. Two-way indicator species analysis produced 13 site groups, which were primarily separated by chemical variables, mainly conductivity, total P and water colour. In partial CCA, the environmental and spatial factors accounted for 38% and 24%, respectively, of explained variation in community composition. A high proportion (almost 40%) of variation explained by the combined effect (spatially-structured environmental) indicated that diatom communities of boreal streams incorporate a strong spatial component. At the level of subecoregions, classification strength was almost equally strong for all sites as for near-pristine reference sites only. Procrustes analysis indicated that spatial factors and patterns in diatom community structure were strongly concordant. Our data support the argument that diatom communities are strongly spatially structured, with distinctly different communities in different parts of the country. Because of the strong spatial patterns of community composition, bioassessment programs utilising lotic diatoms would clearly benefit from regional stratification. A combination of regional stratification and the prediction of assemblage structure from local environmental features might provide the most robust framework for diatom-based assessment of the biological integrity of boreal streams.