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1.
Influences of habitat complexity on the diversity and abundance of epiphytic invertebrates on plants 总被引：10，自引：0，他引：10
SUMMARY 1. The compound influence of habitat complexity and patch size on stream invertebrate assemblages associated with submerged macrophytes was investigated through field sampling of two natural macrophyte species with contrasting leaf morphologies (complex, Ranunculus yezoensis; simple, Sparganium emersum) and an experiment with two artificial plants with different levels of morphological complexity. 2. The artificial plant experiment was designed to separate the effects of habitat area (patch size) and habitat complexity, thus enabling a more rigorous assessment of complexity per se than in previous studies where only a single patch size was used. Simple and complex artificial plants were established with five different patch sizes corresponding to the range found in natural plants. 3. Invertebrates occurred on both complex and simple forms of natural and artificial plants at similar abundances with dipterans and ephemeropterans being predominant. Taxon richness was higher on structurally complex Ranunculus than on simple Sparganium and was similarly higher on the complex artificial plant than on the simple one, over the entire range of habitat patch sizes. Thus, architectural complexity affected the taxon richness of epiphytic invertebrates, independently of habitat scale. 4. On the natural plants there was no difference in the abundance (both number of individuals and biomass) of invertebrates between simple and complex forms, while on artificial plants more invertebrates occurred on complex than on simple forms. The amount of particulate organic matter, >225 μm (POM) and chlorophyll a showed mixed patterns on natural and artificial plants, suggesting that the availability of these resources is not an overriding proximate factor controlling invertebrate abundance on plants. The difficulty of extrapolating from experimental results involving use of artificial plants is discussed, especially when considering the relationship between habitat structure and the occurrence of epiphytic invertebrates on natural plants. 相似文献
2.
Streams form hierarchical, dendritic physical networks, but relatively little is known about how this spatial structure affects community assembly. We investigated interactions between changes over time in macroinvertebrate assemblages and their distribution in space (the space–time interaction) in stream networks. Assemblages were sampled from every tributary, and every reach between tributaries, to determine effects of network position on assemblage composition, in four West Coast, South Island, New Zealand, headwater networks. Using canonical redundancy analysis, we found that macroinvertebrate assemblages were significantly spatially structured and species assemblages changed significantly between two sampling periods. The most important environmental variables (averaged over all AIC models) explaining change in assemblage composition were related to disturbance, local habitat/resources and habitat size. The lack of a significant interaction between space and time, however, indicated the spatial pattern of assemblages remained the same over time, regardless of changes in assemblage composition. Consistent spatial structuring could be the result of unchanging processes such as those arising from the universal nature of stream topology and hydrology acting both on habitat‐ and dispersal‐ related community processes. Thus, we conclude that although community assemblages changed over time, the spatial arrangement of communities could potentially be predicted from stream network topology and hydrology. 相似文献
3.
底栖动物是河流生态系统中食物链的重要环节。通过对长江、黄河、东江和拒马河等河流野外调查和采样分析研究了河床底质组成对底栖动物群落结构的影响规律。研究结果发现,不同河床底质组成中的底栖动物结构差别很大,不同地理位置而相同底质条件和水力条件的河流底栖动物群落组成相似,说明河床底质是影响河流底栖动物群落结构的关键因素,受地理位置和大气候的影响不大;利用多项生物指标分析了不同河床底质组成中底栖动物群落的多样性,卵石河床且有水生植物生长的河流底栖动物物种组成最丰富,大河中沙质河床不稳定,未采集到底栖动物;不同底质类型河床中的优势种群亦不同。并分析了采样所得底栖动物物种数与采样面积之间的关系,符合前者随后者呈幂指数增加的规律,当实测采样面积为1～2m^2时物种数变化不大,建议一般情况下最小采样面积应为1m^2。 相似文献
4.
Significant variations in four biological measures of water quality with stream order and river basin were demonstrated for streams of the Black and Osage river basins of Missouri. Water quality criteria specific for each order and basin were then developed.Benthic macroinvertebrates from springs and stream orders 3–8 in the two river basins were sampled quarterly for one year with riffle nets and artificial substrate samplers. A total of 548 samples were taken at 137 stations. The average annual macroinvertebrate density, index of diversity, number of taxa, and number of mayfly and stonefly taxa were determined for each station. These measures showed significant differences (p < 0.05) across stream order within and between the two river basins. Total taxa, total mayfly and stonefly taxa, and diversity were highest in orders 4 and 5 with decreased values in lower and higher stream orders. Maximum organism densities occurred in intermediate order streams. These differences were attributed to the succession of physical changes from headwaters to mouth within each river and to the unique geomorphology of each catchment basin.Water quality criteria based on three of the four measures described above (with 95% confidence limits) were established for each stream order in each river basin. Criteria for the Osage River basin were then used to identify three streams in the basin affected by environmental disturbances (stream impoundment, channelization and sewage discharge). The use of order- and basin-specific criteria assures that the biological differences between streams caused by environmental disturbance can be distinguished from the natural biological differences between streams of different orders and drainages. 相似文献
5.
Relationships between avian diversity and habitat area are assumed to be positive; however, often little attention has given to how these relationships can be influenced by the habitat structure or quality. In addition, other components of biodiversity, such as functional diversity, are often overlooked in assessing habitat patch value. In the Sandhills Ecoregion of Georgia, USA, we investigated the relationship between avian species richness and functional diversity, forest basal area, and patch size in pine forests using basal area as a surrogate for overstory structure which in turn impacts vegetation structure and determines habitat quality within a patch. We conducted bird surveys in planted mature pine stands, during breeding season of 2011. We used three classes of stand basal area (BA): OS, overstocked (BA ≥ 23 m2/ha); FS, fully/densely stocked (13.8 m2/ha ≤ BA < 23 m2/ha); and MS, moderately stocked (2.3 m2/ha ≤ BA < 13.8 m2/ha). MS patches showed more structural diversity due to higher herbaceous vegetation cover than other two pine stocking classes of patches. Total species richness and functional richness increased with the size of MS patches, whereas functional divergence decreased with the size of OS patches (p < 0.05). Functional richness tended to be lower than expected as the size of OS patches increased. Greater richness of pine–grassland species was also found at MS patches. Percent cover of MS patches within a landscape influenced positively the richness of pine–grassland species (p < 0.05). Our results suggest that (a) avian species–habitat area relationship can be affected by habitat quality (structural diversity) and varies depending on diversity indices considered, and (b) it is important to maintain moderate or low levels of pine basal area and to preserve large‐sized patches of the level of basal area to enhance both taxonomic and functional diversity in managed pine forests. 相似文献
6.
Spatial and temporal patterns of distribution and abundance of a tropical fish assemblage in a seasonal Sargassum bed, Cabo Frio Island, Brazil 总被引：1，自引：0，他引：1
The patterns of distribution and abundance of a fish community were influenced by the magnitude of the canopy of Sargassum furcatum . It is suggested that the fish community in the sublittoral of Farol Beach is structured mainly by factors related to the availability of space and habitats. Quantitative data were collected by visual census techniques, along a belt of 30X2 m in each habitat. Fish diversity was greater in S. furcatum bed and in the rocks, than in the sand where there is less structural complexity. The fish density was related to the macroalgal biomass. Correspondence analysis and cluster analysis were used to describe and compare fish assemblages in three different habitats. The association observed between the juveniles of the sparid Diplodus argenteus , the grunt Haemulon aurolineatum and the surgeonfish Acanthurus bahianus and the different habitats in the summer, and juveniles of the other species in the autumn, indicates a pattern of recruitment of the species in these periods. 相似文献
7.
Stream community structure in relation to spatial variation: the influence of mesohabitat characteristics 总被引：13，自引：5，他引：13
Beisel Jean-Nicolas Usseglio-Polatera Philippe Thomas Sandra Moreteau Jean-Claude 《Hydrobiologia》1998,389(1-3):73-88
Community structure of benthic macroinvertebrates was studied in six first- through fourth-order streams in northeast France,
to elucidate changes in richness, abundance, diversity and evenness of mesohabitat assemblages as a function of environmental
conditions. Patch samples were subjected to multivariate analyses to determine: (i) relationships among seven indices describing
community structure (structure parameters); (ii) relationships among seven environmental variables; (iii) the relationship
between community structure and environmental characteristics of patches. Faunal data showed that indices measuring the distribution
of individuals among taxa (evenness, dominance) and richness are prominent in describing the structure of macroinvertebrate
communities of mesohabitats. The analysis of environmental data demonstrated a major differentiating ability of current velocity
and strong inter-relations among in-stream hydraulic-dependent parameters in structuring the mesohabitat environment. The
co-structure (= relationship) between community organization and environmental variables indicated that substrate may be a
primary determinant of community structure. Current velocity and water depth emerged as secondary factors. Trends in community
structure were closely related to the spatial variability of mesohabitats. Species richness increased with habitat heterogeneity.
Total abundance increased with trophic potentialities of patches. Equitability and diversity seemed to increase with patch
stability.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
8.
Many efforts have been undertaken to reduce the impairment of stream ecosystems by wastewaters and other pollution, leading to a remarkable improvement of the water quality in most parts of Central Europe. Actually, the most severe disturbance to stream systems in Central Europe is the structural degradation of stream morphology. Restoration practices increasing the structural heterogeneity of formerly degraded stream sections are necessary to create new habitats at different scales that could provide habitat for a diverse invertebrate community. Increasing biodiversity of aquatic invertebrates strengthens the ecological integrity of streams and is therefore a desirable goal in stream restoration. Nevertheless, recent studies focusing on the effect of structural restoration of stream sections often displayed results that did not really met the preset goal of increasing invertebrate diversity. This might be due to sometimes severe disturbance caused by the restoration practice itself, impairing the established invertebrate community in the restored stream section. Additionally, the potential for immigration of new species into the restored stream section is often limited. Therefore, several important prerequisites must be accounted for in the planning of restoration practices to improve structurally degraded stream sections, when the goal of restoration is increasing invertebrate diversity. 相似文献
9.
Aurélio F. Tonetto Ricardo Cardoso‐Leite Cleto K. Peres Pitagoras da C. Bispo Ciro Cesar Z. Branco 《Freshwater Biology》2014,59(8):1687-1694
- Habitat complexity is thought to play an important role in various ecological communities, but its role under variable natural conditions is not well understood, particularly in lotic habitats where the complexity of the substratum influences the diversity and abundance of the benthic community.
- We investigated the effects of the habitat complexity of the substratum, as represented by fractal structure, on the establishment of stream macroalgae. We also analysed the influence of hydraulic conditions associated with variations in the fractal dimension of the substratum. We hypothesised that habitats with higher surface complexity would have higher macroalgal abundance and that hydraulic conditions would affect macroalgal establishment differently on surfaces of differing complexity.
- We designed a field experiment to elucidate the role of habitat complexity (represented by the fractal dimension and density of roughness elements) and consequent hydraulic conditions (assessed by the Reynolds number and drag forces) on algal growth. Sterile artificial substrata with five levels of complexity were placed in four unshaded streams. After 60 days of complete submergence, the substrata were removed from the streams, and the per cent cover of macroalgae was measured.
- We used a principal components analysis (PCA) to reduce the dimensionality and collinearity among our variables (fractal dimension, density of roughness elements, Reynolds number and drag force) and summarise them adequately. Axis 1 (PC1) values were used in a linear model to assess the relationship between the variables and macroalgal cover.
- PC1 explained 82.2% of the variability in substratum complexity and hydraulic condition. The fractal dimension and density of the roughness elements were negatively related with PC1, whereas the Reynolds number and drag force were related positively. Hydraulic conditions differed among each level of complexity, with the Reynolds number and drag force decreasing with increasing complexity. Macroalgal cover increased on surfaces with lower turbulence and drag force, indicating that less aggressive conditions are suitable for macroalgal colonisation. Additionally, the establishment of macroalgae was greatest on the leading edge of flat‐top ridges, where the water velocity slows and the current changes direction.
- Habitat complexity and hydraulic conditions play an important role in the establishment of macroalgae in streams and could explain their naturally patchy distribution.
10.
Simone Fattorini Diana M. P. Galassi Giovanni Strona 《Insect Conservation and Diversity》2016,9(4):369-373
- Human presence can affect biodiversity in many ways. If anthropization is one of the major drivers of species extinctions, at the same time, human induced increase in environmental heterogeneity may also increase species richness.
- In many cases, however, heterogeneity is not enough to explain the unexpectedly high biodiversity found in some densely populated areas.
- A possible explanation to such situations is the partial overlap in resource requirements between man and other species, which promotes a tendency for humans to settle in sites characterised by environmental conditions that are particularly favourable also for many other organisms.
- To test this hypothesis, we investigated the relationships between human population and species richness of native (non‐synanthropic) tenebrionid beetles in the Mediterranean islands, many of which have been inhabited by humans for millennia.
- Using partial correlation analyses, we found that tenebrionid diversity increased not only with island area and maximum elevation (used herein as a measure of environmental heterogeneity), but also with human population.
- This may suggest that the islands that were (and are) more accessible and hospitable to humans are also those which can be more easily colonised by tenebrionids, owing to their larger areas and higher environmental heterogeneity.
11.
长江师范学院校园夏季鸟类群落与多样性分析 总被引：5，自引：0，他引：5
2008年3～7月采用样线法对长江师范学院李渡校园鸟类组成和种群数量进行了调查,共记录鸟类6目21科28种,数量1633只,物种多样性指数为3．9204,均匀性指数为1．1765,其中国家“三有”名录鸟类25种,CITES名录鸟类1种。鸟类区系以东洋界成分为主。对不同生境鸟类多样性的分析结果表明：（1）乔灌林鸟类多样性指数和均匀性指数最高,水域鸟类多样性指数最低,建筑区均匀性指数最低;（2）乔灌林与竹林的相似性指数最高,竹林与水域的相似性最低。 相似文献
12.
13.
David L. McCulloch 《Hydrobiologia》1986,135(1-2):61-70
The benthic macroinvertebrate riffle-pool communities of two east Texas streams were sampled monthly for a period of one year. In contrast to previous studies in primarily upland areas, pools in Alazan Creek and Bernaldo Bayou contained significantly higher densities and biomass, as well as a significantly higher diversity and number of taxa. The majority of taxa collected could be characterized as pool adapted organisms, with the Diptera, Ephemeroptera, Coleoptera, and Odonata having greater numbers in pools. Perlesta, Baetis, and Cheumatopsyche were the only genera to have significant numbers in riffles at both sampling sites. A greater number of taxa were restricted to pools at both sampling locations, and although an unstable, sandy substrate was a factor in limiting colonization of riffles, riffles were not as productive as pools even in the presence of suitable substrate conditions. A cluster analysis based on similarity indices indicated that like habitats between streams were more similar to each other, than were adjacent riffle-pool complexes within streams. 相似文献
14.
Aim We investigated partitioning of aquatic macroinvertebrate diversity in eight headwater streams to determine the relative contributions of α and β diversity to γ diversity, and the scale dependence of α and β components. Location Great Dividing Range, Victoria, Australia. Methods We used the method of Jost (Ecology, 2007, 88, 2427–2439) to partition γ diversity into its α and β components. We undertook the analyses at both reach and catchment scales to explore whether inferences depended on scale of observation. Results We hypothesized that β diversity would make a large contribution to the γ diversity of macroinvertebrates in our dendritic riverine landscape, particularly at the larger spatial scale (among catchments) because of limited dispersal among sites and especially among catchments. However, reaches each had relatively high taxon richness and high α diversity, while β diversity made only a small contribution to γ diversity at both the reach and catchment scales. Main conclusions Dendritic riverine landscapes have been thought to generate high β diversity as a consequence of limited dispersal and high heterogeneity among individual streams, but this may not hold for all headwater stream systems. Here, α diversity was high and β diversity low, with individual headwater stream reaches each containing a large portion of γ diversity. Thus, each stream could be considered to have low irreplaceability since losing the option to use one of these sites in a representative reserve network does not greatly diminish the options available for completing the reserve network. Where limited information on individual taxonomic distributions is available, or time and money for modelling approaches are limited, diversity partitioning may provide a useful ‘first‐cut’ for obtaining information about the irreplaceability of individual streams or subcatchments when establishing representative freshwater reserves. 相似文献
15.
淮南地区粉螨群落结构及其多样性 总被引：11，自引：1，他引：11
在淮南地区仓储、人居、工作、野外4类生境中采集粉螨样本,行分离、镜检,共检获粉螨3 650头,隶属于7科20属,共32种。结果表明,其物种数S、丰富度指数R、多样性指数H′排序均为仓储环境>野外环境>人居环境>工作环境,野外环境中粉螨群落的均匀度指数最大,工作环境中粉螨的优势度指数最大。工作和野外环境的群落相似性指数最低,达到极度不相似水平。结果表明,粉螨群落的结构及多样性与其生境条件直接相关,人类活动是较为重要的影响因素。 相似文献
16.
The macroinvertebrate species and assemblages of headwater streams of the River Tyne catchment in northern England were classified and their relationship with environmental variables based on stream structure, water acidity, distance from source and land cover investigated using constrained ordination and logistic regression. Fuzzy classification of data from 322 stream sites generated five assemblages. Stream structure, quantified as an exposure index, was found to be the most important environmental variable, with water acidity also important. Distance from source and land cover had less influence on species and assemblage distribution. A considerable amount of variation in assemblage distribution was explained using a two-variable logistic regression with stream structure (exposure index) and water acidity (pH) in a template. Site structure and water acidity appeared to be related to drift, geology and topography with little anthropogenic influence. The applicability of the habitat template concept for explaining the distribution of stream macroinvertebrates is discussed. 相似文献
17.
Werner Ulrich 《Acta Oecologica》2004,25(3):179-186
The present paper describes basic ecological distributions in a community of beech forest Hymenoptera. It shows that the species diversity–body weight and the density–body weight distributions give rise to a new distribution that relates total community biomass to species diversity. For Hymenoptera this distribution follows a power function with a slope of 1.3. Combining this relation with the species–area and the individuals–area relations resulted in two other distributions that relate community biomass to area and individual numbers. It appeared that population densities decrease when computed over larger areas. The biomass–species diversity relation offers a new and simple way to estimate total community biomass from samples. The possible implications of this distribution to the productivity–diversity debate are discussed. 相似文献
18.
- Groundwater‐fed rivers, such as the chalk streams of southern England, exhibit high levels of stability (e.g. flow and temperature) and physical homogeneity (e.g. depth and substrate grain size). However, growth of instream macrophytes is highly variable depending on season, providing an important but ever‐changing source of cover for stream‐dwelling salmonids, such as brown trout (Salmo trutta).
- In this study, the behavioural ecology of brown trout inhabiting a chalk stream was assessed during periods that included summer and winter. In a reach of the River Lambourn (Berkshire, UK), a combination of physical habitat mapping, electric‐fishing, passive integrated transponder and radio telemetry was used to quantify trout: (1) density relative to physical and thermal characteristics; (2) movement patterns; and (3) performance, in terms of growth.
- Trout density was positively related to depth during winter (February) and spring (May), but not at the end of summer (September). Despite no statistical relation between trout density and macrophytes, periods of strong and no association between density and depth coincided with sparse and extensive macrophyte cover throughout the study reach, respectively.
- Despite being greater for some fish in winter compared to summer, the daily distance moved was generally low (<3.5 m/day). While growth was mostly positive, less mass was gained, and performance deviated farther from optimal levels predicted by a growth model, during periods that included winter.
- A number of factors probably contributed to lower growth in winter, including costs of reproduction, temperatures—which deviated farther from those optimal for growth—and/or an inability to maximise energy intake, e.g. due to time spent holding position in deeper areas as cover provided by macrophytes declined.
- Despite the lack of extremes in chalk stream environments, the behavioural ecology of brown trout appears to be influenced by seasonal variation in instream cover provided by macrophytes. This emphasises the importance of balancing the management (e.g. cutting and removal) of macrophytes with the ecological benefits they provide.
19.
Is resolution the solution?: the effect of taxonomic resolution on the calculated properties of three stream food webs 总被引：4，自引：0，他引：4
- 1 The influence of the level of taxonomic resolution on estimates of food‐web properties was studied in three grassland streams in New Zealand. The food webs, each of which contained ≈ 100 species of algae, macroinvertebrates and fish, were progressively aggregated into higher taxonomic groupings and the effect on food‐web properties was assessed. Aggregation was also carried out differentially on particular taxonomic groups to mimic the usual approach to taxonomy in stream food‐web studies.
- 2 Of the commonly used food‐web properties, mean chain length and linkage complexity varied little with the degree of taxonomic resolution. Estimates of connectance were markedly higher in coarsely resolved (family level) food webs, possibly as a result of a decrease in the number of web elements.
- 3 Connectance, linkage density, linkage complexity and prey : predator ratios, but not mean chain length, were strongly affected by inconsistency in the level of resolution used among different taxonomic groups within a food web.
- 4 In order to make meaningful comparisons among food webs a standardised approach to methodology, resolution and effort is needed.
20.
Quantification of reach-based microhabitat availability for rainbow trout (Oncorhynchus mykiss), considering their microhabitat requirements in two low-gradient streams, northern Japan, was attempted to test for habitat space limitation of local trout density. Underwater observations revealed that fish selected microhabitats of moderate current velocity, relatively greater depth and shorter distance to overhead cover in both streams, although habitat features used and available differed slightly between the streams. Habitat space for fish potentially available in the channel environment was evaluated using principal component analysis (PCA) of both available and used microhabitat. A close relationship was evident in both streams between reach-based microhabitat availability and fish density, which was assessed by a three-pass removal method. Direct estimates of fish microhabitat availability using PCA can contribute to accurate predictions of local fish density and provide insight into the mechanisms responsible for fish–habitat relationships in streams. 相似文献