基于eDNA metabarcoding探究北京市主要河流鱼类分布及影响因素

使用eDNA宏条形码(eDNA metabarcoding)和地笼法检测了北京市3条水系在夏季和秋季两个季节的鱼类多样性, 旨在研究北京市鱼类群落的空间格局特征, 探索适用于北京鱼类生物多样性监测及保护的新方法。结果表明: 在北京市的34个采样点中, 利用eDNA metabarcoding共检测出鱼类55种, 显著高于传统方法所捕获的鱼类种数(35种), 鱼类组成以鲤形目和鲈形目为主。山区河流清水鱼的多样性要显著高于城区河流, 城区河流(北运河水系)群落结构较为单一, 以鲫(Carassius auratus)、麦穗鱼(Pseudorasbora parva)、泥鳅(Misgurnus anguillicaudatus)等耐污种为优势种; 山区河流(潮白河水系及大清河水系)以宽鳍鱲(Zacco platypus)、拉氏鱥(Rhynchocypris lagowskii)、马口鱼(Opsariichthys uncirostris)等为优势种。不同季节影响清水鱼群落结构的环境因子不同, 夏季主要是总溶解固体和电导率, 秋季主要是海拔和温度。清水鱼丰富度与环境因子及人类活动的相关性表明, 清水鱼的丰富度随着总溶解固体及灯光指数增加而显著降低, 且均与海拔、温度等存在显著相关性。本研究证明了eDNA metabarcoding方法用于监测北京市鱼类多样性及其时空分布的可行性。     

Convergence of fish communities from the littoral zone of reservoirs

1. Understanding factors that regulate the assembly of communities is a main focus of ecology. Human‐engineered habitats, such as reservoirs, may provide insight into these assembly processes because they represent novel habitats that are subjected to colonization by fishes from the surrounding river basin or transported by humans. By contrasting community similarity within and among reservoirs from different drainage basins to nearby stream communities, we can test the relative constraints of reservoir habitats and regional species pools in determining species composition of reservoirs. 2. We used a large spatial database that included intensive collections from 143 stream and 28 reservoir sites within three major river basins in the Great Plains, U.S.A., to compare patterns of species diversity and community structure between streams and reservoirs and to characterize variation in fish community structure within and among major drainage basins. We expected reservoir fish faunas to reflect the regional species pool, but would be more homogeneous that stream communities because similar species are stocked and thrive in reservoirs (e.g. planktivores and piscivores), and they lack obligate stream organisms that are not shared among regional species pools. 3. We found that fish communities from reservoirs were a subset of fishes collected from streams and dominant taxa had ecological traits that would be favoured in lentic environments. Although there were regional differences in reservoir fish communities, species richness, patterns of rank abundance and community structure in reservoir communities were more homogonous across three major drainage basins than for stream communities. 4. The general pattern of convergence of reservoir fish community structure suggests their assembly is constrained by local factors such as habitat and biotic interactions, and facilitated by the introduction of species among basins. Because there is a reciprocal transfer of biota between reservoirs and streams, understanding factors structuring both habitats is necessary to evaluate the long‐term dynamics of impounded river networks.     

Macrophyte communities in unimpacted European streams: variability in assemblage patterns, abundance and diversity

Macrophytes are an important component of aquatic ecosystems and are used widely within the Water Framework Directive (WFD) to establish ecological quality. In the present paper we investigated macrophyte community structure, i.e., composition, richness and diversity measures in 60 unimpacted stream and river sites throughout Europe. The objectives were to describe assemblage patterns in different types of streams and to assess the variability in various structural and ecological metrics within these types to provide a basis for an evaluation of their suitability in ecological quality assessment. Macrophyte assemblage patterns varied considerably among the main stream types. Moving from small-sized, shallow mountain streams to medium-sized, lowland streams there was a clear transition in species richness, diversity and community structure. There was especially a shift from a predominance of species-poor mosses and communities dominated by liverwort in the small-sized, shallow mountain streams to more species-rich communities dominated by vascular plants in the medium-sized, lowland streams. The macrophyte communities responded to most of the features underlying the typological framework defined in WFD. The present interpretation of the WFD typology may not, however, be adequate for an evaluation of stream quality based on macrophytes. First and most important, by using this typology we may overlook an important community type, which is characteristic of small-sized, relatively steep-gradient streams that are an intermediate type between the small-sized, shallow mountain streams and the medium-sized, lowland streams. Second, the variability in most of the calculated metrics was slightly higher when using the pre-defined typology. The consistency of these results should be investigated by analysing a larger number of sites. Particularly the need of re-defining the typology to improve the ability to detect impacts on streams and rivers from macrophyte assemblage patterns should be investigated. Electronic supplementary material Electronic supplementary material is available for this article at and accessible for authorised users.     

The effects of water abstractions on invertebrate communities in U.K. streams

There are increasing concerns about the ecological effects of water abstraction and in the UK, these concerns have been hightened by the 1976, 1984 and 1988-92 droughts. This paper assesses macroinvertebrate and environmental changes induced by surface and groundwater abstractions on 22 streams throughout the UK.The approach involved comparative research to assess differences between reference and impacted sites.Using a database comprising 204 sets of biological and environmental data (89 taxa and 16 environmental variables) a preliminary ordination using principle components analysis clearly differentiated three types of sites: upland, lowland and an intermediate type. At this scale, any effects of abstractions on invertebrate communities are shown to be insignificant relative to regional controls. A simultaneous ordination of the environmental and faunal differences between pairs of sites was undertaken separately for each of the three regional groups. Differences are considered as vectors having both direction and amplitude and the analysis elucidates common patterns in the faunal and environmental data. Important changes were observed in two situations: upland streams affected by major diversions as part of hydro-power schemes in Scotland and lowland rivers impacted by groundwater abstractions.No strong patterns of change (either in amplitude or orientation) were demonstrated within any of the taxonomic groups. However, within the upland type some rheophilous taxa were shown typically to be reduced in abundance at impacted sites. Within the lowland type, a consistent pattern in the dataset is demonstrated by a group of taxa that are reduced in abundance at the impacted sites.     

Spatial Distribution and Temporal Variance of Fish Communities in the Channelized and Regulated Vltava River (Central Europe)

Spatial distribution and temporal variations of fish communities in a channelized portion of the Vltava River (Central Europe) were investigated from May to October 1992. Fish abundance and species number were collected monthly during diel samples in the main channel and a large oxbow. To determine differences in fish communities we chose the low-flow period when maximal differences in physical environment between habitats are expected. Fish community patterns from the main channel and oxbow differed only in abundance of ecological groups; the main channel had higher abundance of rheophilic species, whereas eurytopic species were more abundant in the oxbow. However, our analysis revealed significant differences in temporal variations between habitats. Fish abundance usually varied unpredictably over day-night periods in the main channel, whereas in the oxbow we observed a pronounced peak in fish abundance from morning to mid-afternoon. Diel changes in fish abundance in the oxbow corresponded to occurrence of low dissolved oxygen during afternoon and night-time periods. The effect of oxygen depletion induced by strong organic pollution limited the oxbow suitability for fishes. Similar habitats are usually occupied by limnophilic and phytophilic species that were absent in our samples. Our results suggested that man-induced high variability of physical environment decreased variability in fish community.     

Effects of disturbance caused by selective timber extraction on fish communities in Sabah, Malaysia

To examine the effects of selective timber extraction on fish communities in Sabah, Malaysia, quantitative samples of fishes were taken from thirteen streams running through undisturbed rainforest or through forest that had been selectively logged 3–18 years previously. Multivariate analysis (canonical discriminant analysis and cluster analysis) indicated that mesohabitats within streams (riffles and pools) and differences in stream size were more important in determining community structure than logging history. Riffles in streams running through logged or undisturbed forest were indistinguishable using relative biomass or abundance data, as were pools from small streams (approximate order 2). Fish communities from pools in larger streams showed some separation in multivariate space corresponding to a complex set of relative changes in abundance and/or biomass between species. However it was difficult to unambiguously assign such changes to logging regime alone. There appeared to be some differences in fish communities between streams in recently-logged (3–7 years) and old-logged (17–18 years) areas related to abundance or biomass of three cyprinids (Garra borneensis, Lobocheilos bo and Osteochilus chini). Only one species, Pangio mariarum, was not found in streams in logged forest, but it was only found at one location in undisturbed forest. A number of other species showed significant differences in abundance or biomass between sites but most of these were only present at some sites and in low abundance. Principal components analysis of habitat data showed that riffle sites were homogeneous whatever their logging history as were pools in unlogged large streams. Pools in logged large streams were significantly more heterogeneous but in a random rather than systematic manner. It is concluded that the type of selective logging practices used locally have low impact on fish communities through mechanisms of persistence and/or rapid recolonisation.     

Microcrustacean communities in streams from two physiographically contrasting regions of Britain

ABSTRACT. Benthic microcrustaceans were sampled from forty-three streams in two physiographically contrasting regions of Britain: lowland southern England and upland Wales. Lowland streams had a significantly higher species richness than upland streams and, of the forty-three copepod and cladoceran species identified, only fourteen (33%) were found in both the lowlands and uplands. Canonical correspondence analysis revealed large differences in community structure between regions and between streams within regions. Differences within regions were related to pH, the distance downstream of a site and the presence of upstream impoundments. Variables underlying the large biological differences between regions are also discussed, including differences in chemistry (ionic content), physical parameters (e.g. flow), habitat availability and the influence of species biogeography. The importance of understanding species ecology and biogeography when assessing pollution impacts on stream communities is emphasized and a model is proposed for predicting the composition of microcrustacean communities in temperate European streams.     

Community structure of fish in lowland streams differ substantially between subtropical and temperate climates

Fish are important in the structuring of other communities and may have large effects on the functioning of aquatic ecosystems. The structure of fish communities, in turn, seems to differ with climate. We compared the characteristics of fish assemblages in lowland streams located in two contrasting climates (cold-temperate Europe and subtropical South America) by use of published and unpublished data on streams of similar depth, width, and slope (n total?=?91 streams). We also selected a subset of seven comparable little-affected streams in the two contrasting climates: temperate (Denmark, 55°?C57°N, Dk) and subtropical (Uruguay, 30°?C35°S, Uy) and compared the fish community structures in relation to environmental characteristics. We then analysed a series of potential explanatory factors behind the patterns observed, in particular the effect of ambient temperature, by comparing temperature-corrected community metabolism. Significantly higher species richness, higher densities, lower biomass, smaller mean body size, and lower mean weight of fish were observed for the subtropical streams than for the temperate streams, both in the literature review and in the subset of streams. Several characteristics of fish assemblages in streams may be explained by direct and indirect effects of temperature. Accordingly, fish in subtropical systems had a temperature-corrected community metabolism I?m^?2 equal to that of fish in temperate systems, indicating that temperature, besides historical factors, is an important driver of different size structures. Our findings concur with differences previously found in littoral areas of shallow lakes, suggesting that these patterns are not restricted to running waters. Our results elucidate how fish community structure might be affected by increases in temperature triggered by climate warming.     

Comparative Environmental Assessment in the Studies of Benthic Diatom,Macroinvertebrate, and Fish Communities

Community response to environmental gradients operating at hierarchical scales was assessed in studies of benthic diatoms, macroinvertebrates and fish from 44 stream sites in the New York City watershed. Hierarchical cluster analysis (TWINSPAN) of diatoms and fish partitioned the study sites into four groups, i.e., acid streams, reservoir outlets and wetland streams, large eutrophic streams, and small eutrophic streams; macroinvertebrate TWINSPAN distinguished an additional group of silty eutrophic streams. The correspondence among the three assemblage TWINSPAN groupings was moderate, ranging from 51 to 57%. The similarity across the four major group types was the highest among large eutrophic stream and acid stream assemblages, and the lowest among small eutrophic stream assemblages. Stepwise discriminant function analysis revealed that environmental factors discriminated most effectively the diatom grouping and least effectively the fish grouping. The best environmental predictors for diatom and macroinvertebrate grouping were conductance and percent surface water, while population density was most powerful in separating the fish groups. Carbaryl was the only pesticide that correlated with macroinvertebrate grouping. Partial redundancy analyses suggested a differential dependence of freshwater communities on the scale of the environmental factors to which they respond. The role of small‐scale habitat and habitatland cover/land use interaction steadily increased across the diatom, macroinvertebrate, and fish assemblages, whereas the effect of large‐scale land cover/land use declined.     

Distribution patterns of blackfly (Diptera: Simuliidae) associations in two Irish river systems

Nine blackfly species were found in two river systems in south western Ireland. Their distribution patterns reflected the three main types of running waters: head waters and mountain brooks; meadow streams and river sections at lower altitudes; lake outlets. Cluster analyses showed correlations between the five most dominant blackfly species and stream sites, as well as with some environmental factors. Larval gut analyses demonstrated that in general the supply of suspended algae determined larval gut content, but there were distinct differences in food utilization between associated larvae.     

Effects of upland clearcutting and riparian partial harvesting on leaf pack breakdown and aquatic invertebrates in boreal forest streams

1. Leaf litter breakdown and associated invertebrates were compared among three logged and three reference stream reaches 2–3 years before and 3–4 years after logging to assess the environmental impacts of partial‐harvest logging as a novel riparian management strategy for boreal forest streams. 2. Partial‐harvest logging at three sites resulted in 10, 21 and 28% average basal area removal from riparian buffers adjacent to upland clear‐cut areas. 3. Leaf litter breakdown rates were not significantly different between reference and logged sites after logging, but litter breakdown was significantly different from year to year at all sites. 4. Significant post‐logging differences in aquatic invertebrate communities were detected at only one of the three logged sites. These differences were largely the result of increases in some leaf‐shredding stoneflies and a detritivorous mayfly and a decrease in a chironomid group 2–4 years after logging. This site where significant change was detected had the lowest intensity of riparian logging (average 10% removal) but the highest proportion of the catchment area that was clear cut (85%). 5.The post‐logging differences in invertebrate communities at this site were more related to catchment‐wide influences (e.g. weather patterns, water yield, possibly upland clearcutting) than to reach‐level disturbances from riparian logging. 6.The study indicates that partial‐harvest logging in riparian buffers at up to 50% removal should pose little risk of harm to leaf litter breakdown processes or aquatic invertebrate communities beyond any impacts that might arise from upland logging disturbance or catchment‐wide influences. However, the results should be viewed in the context of the natural disturbance (summer drought conditions) through the post‐logging assessment period of this study. Post‐logging summer drought conditions may have masked or confounded logging impacts on streams.     

Colonization and ecological development of new streams in Glacier Bay National Park, Alaska

SUMMARY 1. Colonization and ecological development of postglacial freshwater communities was investigated in Glacier Bay National Park, south-eastern Alaska, following the rapid recession of a Neo-glacial ice sheet within the last 250 years.
2. Environmental variables shown to be most significant in stream development were temperature, flow regime and sedimentation.
3. The Chironomidae (Diptera) were the pioneer invertebrate colonizers of newly emergent streams arising as meltwater from receding ice sheets and displayed a distinct pattern of succession with stream maturity.
4. Ephemeroptera and Plecoptera colonized warmer clearwater streams, but Trichoptera had a minimal role in invertebrate community development.
5. Establishment and production of salmonid fish populations in the new streams related principally to stream flow and sediment characteristics.
6. Future pathways along which the streams may develop is probably dependent on the degree of large organic debris input.
7. Stream development, structure and function are summarized including reference to theories of ecosystem development, ecological succession and community stability.     

Spatial variability in macroinvertebrate assemblages: comparing regional and multivariate approaches for classifying reference sites in South Africa

Spatial variability in macroinvertebrate assemblages was examined with the aim of evaluating the utility of regional classification systems in aquatic bioassessment. Sampling was undertaken at reference sites in the Western Cape and Mpumalanga, South Africa, using the rapid bioassessment method SASS4 (South African Scoring System Version 4). Multivariate analysis of macroinvertebrate assemblages showed that assemblages varied regionally with differences most apparent in upland areas, i.e. mountain streams and foothill-cobble beds, with lowland areas less regionally distinct. Within regions, longitudinal zonation into upland and lowland areas was important, with sites grouping on the basis of broad geomorphological zones or subregions. Of the upland sites, differentiation into mountain streams and foothill-cobble beds was not evident, although overall variability of assemblages within upland areas, in particular the Western Cape, was very high. In general, a priori regional classification of sites using the hierarchical spatial framework developed in South Africa provided a useful framework for preliminary classification of reference sites. Groups of sites based on a posteriori analysis of macroinvertebrate data, however, provided a more robust classification than any regional classification. Spatial classifications therefore offer geographic partitions within which to expect somewhat similar conditions, and regional reference sites selected within the context of the spatial framework are likely to be more representative of specific river types than those selected without using the framework. Classification of sites needs to be an iterative process that allows for subjective a priori regional classifications to be modified on the basis of independent, objective a posteriori classification of biological assemblages.     

Resilience of fishes and invertebrates to prolonged drought in two California streams

Long-term data are needed to assess spatial and temporal variability of communities and their resilience to natural and anthropogenic disturbances, particularly in climatic regions marked by high interannual variability (e.g. mediterranean-climate). A long-term study at four sites on two streams in mediterranean-climate California (annual sampling over 20  yr) allowed us to quantify the influence of a 5-yr prolonged drought on stream invertebrate and fish communities. Invertebrate community composition did not show recovery following drought. The primary environmental factors influencing community composition, identified through principle components and multiple correspondence analyses were precipitation and flow permanence. Invertebrate taxon richness and abundance exhibited few responses (some site specific) and recovered quickly. Native fish abundance was lowest during the drought period and highest during the wet years that occurred at the end of the study period. Importantly, the prolonged drought facilitated the establishment and success of the invasive green sunfish (Centrarchidae: Lepomis cyanellus ) that was then resilient to subsequent large flow events. There was high spatial synchrony in the temporal changes among all four sites, and three distinct periods were identified: early drought, late drought, and post-drought years. However, we still found differences among sites along the flow permanence gradient from temporary to perennial in the response to drought of both invertebrate and fish assemblages likely as a result of changes in substrate, vegetation, and other habitat characteristics. The observed lack of resilience and negative impacts to biodiversity due to prolonged drought associated with long-term habitat changes is important because hydroclimatic extremes are predicted to increase in frequency and magnitude with global climate change.     

Organization patterns of headwater-stream fish communities in the Upper Paraguay–Paraná basins

We compared environmental influences on the assemblages of stream fishes of contiguous but biogeographically distinct parts of the Upper Paraguay and Paraná basins in Brazil, aiming to describe the main distribution patterns of fish species in the headwater streams. We analyzed bimonthly samples in 10 streams in each basin from January to November 2004. Sixty fish species were collected, including 40 species in streams of the Paraguay Basin and 42 species in streams of the Paraná Basin. The species abundance rank did not differ between the basins. We found a clear differentiation between the Paraguay and Paraná stream fish assemblages. There were significant differences in species composition among streams, but no seasonal differences in species composition. Connectivity between streams explains the differences in species composition for the Paraguay streams, but not for the Paraná streams. Hydrological characteristics were the main factors determining species distribution in both basins, suggesting that the migratory capacity of each species and biogeographical barriers may act to filter the local species composition from the total species pool of colonizers. Handling editor: S. M. Thomaz     

Ecological relationships between stream communities and spatial scale: implications for designing catchment-level monitoring programmes

1. Stream communities are structured by factors acting over multiple spatial and temporal scales. Identifying what factors are driving spatial patterns in stream communities is a central aim of ecology.
2. Here we used two large European data sets of fish, invertebrates, macrophytes, benthic diatoms and environmental data in two stream groups (lowland and mountain) to determine the importance of variables at different spatial scales (geographical, regional, local) on community structure.
3. Both geographical position and ecoregion were selected first in canonical correspondence analysis (CCA), clearly showing the broad spatial gradients covered in the data set. Secondary predictors (after accounting for spatial and/or ecoregion effects) were similar between stream groups and among the four organism groups. In particular, conductivity and N concentration were strong predictors reflecting catchment land use.
4. Using partial CCA, we assessed the individual importance of the three spatial scales on the community structure of the four organism groups in the two stream groups. The majority of among-site variability (22–29%) was accounted for by local scale variables (e.g. water chemistry and substratum type), with regional and spatial variables accounting 11–13% and 5–6%, respectively. Our findings indicate that the four organism groups are responding similarly to the different levels of spatial scale, implying much redundancy which should be consider when implementing studies of bioassessment.     

Drift patterns in a high Andean stream

The drifting of invertebrates was sampled for six 24-hour periods from September 1976 to July 1977 in a small stream of the paramo of the Ecuadorian Andes. The composition of the drift is similar to that of the benthos, though percentages may differ markedly. Drift is relatively constant throughout the year, except in March when unusually high rates were noted; at this same period a marked reduction in the benthos was also observed. Diel periodicities in the drift are unclear, although on the whole drift is more important during the daytime; when individual data series are analyzed, weak patterns of day or night drifting can be recognized in some groups. The input of insects through drift from the small streams is thought to be an important source of food for the salmonid fish inhabiting the larger torrents.     

Quantifying the direct and indirect effects of flow‐related disturbance on stream fish assemblages

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Local and ecoregion effects on fish assemblage structure in tributaries of the Rio Paraíba do Sul, Brazil

1.  We examined the effects of physical and chemical habitat variables and ecoregions on species occurrence and fish assemblage structure in streams of the Paraíba do Sul basin, in southeast Brazil.
2.  Fish and environmental data were collected from 42 sites on 26 first to fourth order streams (1 : 50 000 map scale) in three ecoregions. The sites occurred in one valley and two plateau ecoregions at altitudes of 40–1080 m and distances of 0.1–188 km from the main channel of the Rio Paraíba do Sul. Physical habitat (substratum, riparian cover, habitat types) and water quality (dissolved oxygen, pH, temperature and conductivity) variables were measured at each sampling site.
3.  A total of 2684 individuals in 16 families and 59 species were recorded.
4.  Ecoregion was a better predictor of the fish assemblage than the other environmental variables, according to the differences between the mean within-class and mean between-class similarities in assemblage data.
5.  Differing landscape characteristics were associated with differing local variables and thereby with differing fish assemblage structures. Riffles, shrub, grass, dissolved oxygen, conductivity and temperature were closely related to fish assemblage structure.
6.  Fish assemblages in sites far from the main river and at higher altitudes also differed from those near the Paraíba do Sul main channel, presumably as a result of differences in connectivity, covarying environmental factors and anthropogenic influence.
7.  These results reinforce the importance of understanding how stream communities are influenced by processes and patterns operating at local and regional scales, which will aid water resource managers to target those factors in their management and rehabilitation efforts.     

Are biological classifications of headwater streams concordant across multiple taxonomic groups?

1. Studies assessing human impacts on freshwater ecosystems are typically based on a single taxonomic group, often macroinvertebrates or fish. Unfortunately, the degree to which such macroinvertebrate or fish‐based surveys can be generalised across other taxonomic groups remains largely unknown. A prerequisite for useful generalisations is that different taxonomic groups exhibit concordant patterns of community structure across sites. 2. We examined the concordance among fish, benthic macroinvertebrates and bryophytes in 32 streams in a boreal catchment in Finland. Our goal was to test how consistently different taxonomic groups classify stream sites; for example, can site groupings based on macroinvertebrates be used as a surrogate for bryophyte or fish assemblage classification? 3. Our results show that community classifications in headwater streams are not concordant across taxonomic groups, at least not at the within‐river system scale. The lack of concordance reflected the fact that all three groups responded to different environmental factors. Macroinvertebrate community structure was mainly correlated with stream size and pH, whereas bryophytes were related to water colour, nutrient content and in‐stream habitat variability. Fish community structure was best described by stream depth, substrate size and water oxygen concentration. 4. Our results suggest that great care should be taken when typologies based on benthic macroinvertebrates, or any other taxonomic group, are extrapolated to other groups in creating typologies of lotic environments.