Hydromorphology – major results and conclusions from the STAR project

The major results and conclusions of the two papers in the hydromorphology section of the Hydrobiologia special issue on the EU STAR project are summarised. Several key findings have emerged from this research. Firstly, the hydromorphological characteristics of rivers between different geographical regions of Europe were found to vary considerably with rivers in each region possessing distinctive hydromorphological characteristics. Secondly, the hydromorphological attributes that most strongly influence two existing hydromorphological indices (the Habitat Quality Assessment and the Habitat Modification Score) were identified and attention was drawn to the accurate definition and recording of these attributes in field surveys and training courses. Thirdly, links between hydromorphological characteristics and macroinvertebrate quality indices were investigated. Two types of bank modification (resectioning and reinforcement) were significantly correlated with two biotic indices (EPT taxa and MTS), while channel modifications were negatively correlated with ASPT. While biotic indices were often strongly correlated with Habitat Quality Assessment they were less strongly related to Habitat Modification Score suggesting that physical habitat diversity may be more important in determining macroinvertebrate community structure than morphological alteration. The papers in this section provide important underpinning research for the implementation of the European Water Framework Directive. In both papers suggestions are made for further research on the hydromorphology of European rivers.     

Macroinvertebrate communities in Phragmites australis (Cav.) Trin. ex Steud. reed beds and open bank habitats in central victorian streams in Australia

Reed invasion is a common phenomenon of open streams with disturbed riparian vegetation in river catchments. Knowledge of the effects of such vegetation change on aquatic communities is fundamental to river management. Macroinvertebrate fauna in Phragmites australis (Cav.) Trin. ex Steud. and open bank habitats were examined in three rivers in central Victoria in order to understand the effect of such littoral habitat on macroinvertebrates. Data were analysed using Partially Nested Factorial ANOVA with season, river and habitats as main effects. Habitat structure had a significant effect (p<0.05) on macroinvertebrate species richness, however this was not seasonally consistent across the three rivers. There was a significant increase (p<0.05) in macroinvertebrate taxa richness in Phragmites habitats during winter and spring seasons. Total abundance of taxa showed no consistent significant differences in the two habitats. Results of Canonical Analysis of Principle Coordinates indicated significant differences (p<0.05) in macroinvertebrate assemblages between Phragmites and bare bank habitats in all seasons. Habitat selection by taxa could be related to the microphysical environment of the habitats. This study suggests that reed beds create important littoral habitat structures which support diverse macroinvertebrate assemblages.     

REPLY TO COMMENTS BY DR D H R HELLWIG ON PAPERS BY J.U. GROBBELAAR,M.K. SEELY & O.B. KOK

The aim of this study was to assess and compare the water quality of the Gwebi and Mukuvisi Rivers, on the basis of selected physicochemical variables and macroinvertebrate community structure. Five sites where selected on both rivers and these were sampled on three separate occasions between January and July of 1998. The water variables measured were the concentrations of iron, chromium, zinc, lead, copper, manganese, chlorides, fluorides, sulphates, total phosphates, nitrates, ammonia, total dissolved salts, dissolved oxygen, biological oxygen demand, as well as pH, conductivity, temperature, water surface velocity and discharge. The concentration of most of the chemical variables was relatively similar along the course of the Gwebi River, but there were drastic increases in the levels of iron, chromium, copper, zinc, chlorides, fluorides, sulphates, and ammonia along the Mukuvisi River. The two rivers were different with respect to the physicochemical variables, with the exception of the first site on the Mukuvisi, which was similar to sites on the Gwebi River. This was because of the differences in the levels of human activities on the two rivers. Industrial, sewage and domestic pollution has had an adverse effect on the water quality of the Mukuvisi River. There was a sharp decline in the number of macroinvertebrate taxa along the Mukuvisi River. The lower reaches of the river where dominated by oligochaetes and Chironimidae larvae. Sample score classification of water quality based on the South African Scoring System Version 4 (SASS4) showed that most of the Mukuvisi river had poor quality water quality, whilst much of the Gwebi River had fair quality water. The HABS1 habitat assessment index was used to assess habitat quality at each site. Although much of the Mukuvisi recorded fair to good habitat scores and had generally higher habitat scores than sites on the Gwebi, the SASS scores were generally lower compared to those along the Gwebi. The sample scores and average score per taxon (ASPT) of the SASS4 showed that the Mukuvisi River was of much lower quality than the Gwebi. Both the sample score and ASPT were negatively and significantly (p<0.05) correlated to most of the physicochemical variables. The water quality variables accounted for 61.1% and 59.0% of the differences in the sample score and ASPT respectively. There was a marginal decrease in the Margalef and Shannon indices along the Gwebi River, but the Simpson's index remained relatively constant. Along the Mukuvisi River, there was a clear and distinct decrease in the magnitude of all three diversity indices, indicating decreasing macroinvertebrate community structure. The change in water physicochemical variables accounted for 61.3%, 69.2% and 87.2% of the changes in the Margalef, Shannon and Simpson's index respectively. The study provides evidence that the changes in macroinvertebrate community structure along the Mukuvisi River is due to decline in the water quality. On the Gwebi, water quality is not the main factor determining macroinvertebrate community structure.     

Macroinvertebrate community dynamics in a temperate European Atlantic river. Do they conform to general ecological theory?

Spatial and temporal dynamics of macroinvertebrate communities have usually been linked to several environmental and anthropic factors. The aim of this study is to elucidate how important are these factors in structuring macroinvertebrate communities from temperate regions. Regarding the macroinvertebrate number of taxa, the Habitat Template Model, the Dynamic Equilibrium Hypothesis and the Intermediate Disturbance Hypothesis will be tested in order to know how important the diversity of instream elements and the hydrological disturbance frequency are in defining the macroinvertebrate taxonomic richness. Thus, the structure and composition of macroinvertebrate communities were analysed in nine sites of the Pas River basin, a temperate Atlantic basin in northern Spain, during winter, spring, summer and autumn 2005, together with water physicochemical and environmental characteristics. Macroinvertebrate abundance increased downstream and during summer, probably favoured by lower hydraulic stress and water organic enrichment. As predicts the Habitat Template Model, the macroinvertebrate number of taxa was related to habitat heterogeneity. However, no clear relationship amongst macroinvertebrate richness and water quality was found. The macroinvertebrate taxonomic richness did not correspond exactly with the Dynamic Equilibrium Hypothesis and the Intermediate Disturbance Hypothesis because it was relatively high in the absence of hydrological disturbances (summer). Thus, disturbance events may play a secondary role in determining the seasonal dynamic of the number of taxa. However, hydrological disturbances can be considered the most important factors explaining the seasonal pattern of macroinvertebrate abundance. On the other hand, spatial patterns of macroinvertebrate community structure and composition were mainly determined by resource availability, hydraulic conditions, habitat heterogeneity and human alterations, whilst hydrological predictability and resource availability might play a major role in determining seasonal dynamics.     

Habitat diversity and ostracod distribution patterns in Belarus

Ostracod diversity and abundance was studied in 10 different types of water bodies of Belarus (bogs, brooks, canals, oxbows, ponds, reservoirs, rivers, springs, shoal of lake and temporary pools). Hydrochemical variables, sediment, and vegetation were analyzed. In total 156 different localities were investigated. Habitat diversity was based mainly upon the closely correlated hydrochemical variables of mineralization (hardness total and carbonate, conductivity, total value of dissolved substances), although bottom, vegetation characteristics and other factors (pH, dissolved oxygen, nutrients) were also significant. The ostracods found included 62 species in 27 genera comprising 8 cosmopolitan, 17 Holarctic, 13 Palearctic species; 21 of these species are known from central and southern Europe and adjacent areas, while 3 are characteristic for eastern Europe. The distribution of freshwater ostracod assemblages reflected the habitat and depended on water body type. Heterogeneous oxbows and temporary pools supported 37 species, while other types of pool maintained only 27–14 species. The population density of different species varied from 0.5 to more than 10 000 ind./m². Indices of local alpha diversity were significantly correlated with the number of species and temperature and were maximal in heterogeneous habitats. The variation of population density was not connected with habitat patterns but appeared to be regulated by the biotic interactions in the community. Habitat diversity, verified by the beta-diversity indices, enabled us to find localities with a similar heterogeneity level and species richness. Beta-diversity values were independent of species number as well as abundance but a significant positive correlation (p < 0.05) was found with temperature, pH and dissolved oxygen. This index probably reflected the general patterns of different localities.     

How does landscape context contribute to effects of habitat fragmentation on diversity and population density of butterflies?

Aim Studies on habitat fragmentation of insect communities mostly ignore the impact of the surrounding landscape matrix and treat all species equally. In our study, on habitat fragmentation and the importance of landscape context, we expected that habitat specialists are more affected by area and isolation, and habitat generalists more by landscape context. Location and methods The study was conducted in the vicinity of the city of Göttingen in Germany in the year 2000. We analysed butterfly communities by transect counts on thirty‐two calcareous grasslands differing in size (0.03–5.14 ha), isolation index (2100–86,000/edge‐to‐edge distance 55–1894 m), and landscape diversity (Shannon–Wiener: 0.09–1.56), which is correlated to percentage grassland in the landscape. Results A total of 15,185 butterfly specimens belonging to fifty‐four species are recorded. In multiple regression analysis, the number of habitat specialist (n = 20) and habitat generalist (n = 34) butterfly species increased with habitat area, but z‐values (slopes) of the species–area relationships for specialists (z = 0.399) were significantly steeper compared with generalists (z = 0.096). Generalists, but not specialists, showed a marginally significant increase with landscape diversity. Effects of landscape diversity were scale‐dependent and significant only at the smallest scale (landscape context within a 250 m radius around the habitat). Habitat isolation was not related to specialist and generalist species numbers. In multiple regression analysis the density of specialists increased significantly with habitat area, whereas generalist density increased only marginally. Habitat isolation and landscape diversity did not show any effects. Main conclusions Habitat area was the most important predictor of butterfly community structure and influenced habitat specialists more than habitat generalists. In contrast to our expectations, habitat isolation had no effect as most butterflies could cope with the degree of isolation in our study region. Landscape diversity appeared to be important for generalist butterflies only.     

Environmental drivers of macroinvertebrate communities in high Arctic rivers (Svalbard)

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河流岸带湿地沉积物重金属分布对植被物种多样性和底栖动物群落特征的影响

河流岸带湿地栖息地完整性对河流水环境、水生态和水文的安全与健康具有重要意义,为探究河流岸带湿地表层沉积物重金属分布特征及其对植被和底栖动物的影响,对滦河干流上中下游河段表层沉积物、植物群落和底栖动物调查分析,采用生物毒性效应系数法和综合潜在生态风险指数法评价沉积物重金属污染特征,采用植被物种多样性指数和底栖动物完整性指数评价滦河植物和底栖动物群落特征,探究岸带湿地沉积物重金属空间分布与植被及底栖动物群落特征之间关系。结果表明,滦河表层沉积物总体呈清洁水平,但不同河段重金属空间分布差异较大,下游重金属生态危害系数和潜在生态风险指数高于上中游。湿地物种调查共识别维管束植物219种,大型无脊椎底栖动物105种,综合评价结果表明下游植物群落物种多样性和底栖动物群落完整性低于上中游。滦河下游岸带湿地沉积物重金属对生物群落具有生物毒性和潜在的生态风险,降低了植被物种多样性和底栖动物群落完整性。大型底栖动物完整性指数能够综合反映底栖动物群落结构特征变化,对河岸带湿地生态健康评价和监测具有重要意义。     

The bioassessment of fish and macroinvertebrates in a Mediterranean–Atlantic climate: Habitat assessment and concordance between contrasting ecological samples

Human intervention and drought conditions in Mediterranean rivers may necessitate the collection of organisms from a different habitat type to that specified by the original bioassessment protocol; it is therefore critical to understand the consequences of adaptive sampling strategies in these lotic systems. In a survey of 31 streams (2nd–4th order) in northern Portugal we collected separate macroinvertebrate samples from running-water and standing-water habitats and fish samples from a delineated reach, inclusive of all habitat types. In addition to collecting habitat data specific to macroinvertebrates and fish we conducted a generalized River Habitat Survey (RHS) and derived scores designed to report habitat quality and habitat degradation. Ecological data were described in terms of taxonomic structure, functional organization and by biotic indices and interpreted in relation to habitat data, comparing samples within and between sites for concordance. Macroinvertebrates from respective habitats differed in their relationship with habitat variable with running-water samples more strongly related to substrate and water quality and standing-water samples more strongly reflecting habitat characteristics at the reach scale. Running- and standing-water samples from the same-site varied widely, indicating that substituting standing-water for running-water samples in macroinvertebrate-based bioassessment carries a high risk of misclassification. However, a consistent bias in index scores suggests that a habitat-adjusted interpretation of biotic indices could be employed to improve measurement precision. Variation in key parameters of the fish community corresponded to changes in water quality and habitat structure and to reach-scale features recorded by the RHS. Trends between macroinvertebrate and fish measurements indicated common patterns for oxygen/flow sensitive taxa and for trophic organization that were related to similar habitat preferences. Whilst macroinvertebrates demonstrated no relationship with derived scores of habitat quality, the fish-based Index of well-being (Iwb) was strongly related to the Habitat Modification Score. Overall these data indicate how different ecological samples can be used to focus on different aspects of habitat quality and are suggestive of strategies for both the collection and interpretation of ecological data that would improve assessment performance. This study emphasizes the need to adapt assessment methods not only to the species pool but also to the differences in the managed and natural habitat characteristics of these types of Mediterranean streams.     

大型无脊椎动物群落指数和群落数量指数在河流水质评价中的应用

本文介绍了新西兰常用的大型无脊椎动物群落指数(MCI)和大型无脊椎动物群落数量指数(QMCI)的原理及使用方法,并利用MCI和QMCI对新西兰惠灵顿地区40条河流53个监测点进行评价.结果表明:MCI和QMCI均与河流营养指标呈极显著相关关系,可用来监测和评价水体的营养污染状况;二者快速准确地监测出惠灵顿地区河流水质总体良好,但部分河流污染严重,并分析了污染的原因.MCI与QMCI存在极显著相关关系,但MCI与营养指标间的相关关系大于QMCI,可以准确地反映出水体中营养元素的富集状况.     

An index to track the ecological effects of drought development and recovery on riverine invertebrate communities

In rivers, the ecological effects of drought typically result in gradual adjustments of invertebrate community structure and functioning, punctuated by sudden changes as key habitats, such as wetted channel margins, become dewatered and dry. This paper outlines the development and application of a new index (Drought Effect of Habitat Loss on Invertebrates – DEHLI) to quantify the effects of drought on instream macroinvertebrate communities by assigning weights to taxa on the basis of their likely association with key stages of channel drying. Two case studies are presented, in which the DEHLI index illustrates the ecological development of drought conditions and subsequent recovery. These examples demonstrate persistent drought effects months or several years after river flows recovered. Results derived using DEHLI are compared with an established macroinvertebrate flow velocity-reactive index (Lotic-invertebrate Index for Flow Evaluation – LIFE score) and demonstrates its greater sensitivity to drought conditions. Data from a number of rivers in south east England were used to calibrate a statistical model, which was then used to examine the response of DEHLI and LIFE to a hypothetical multi-year drought. This demonstrated a difference in response between sampling seasons, with the spring model indicating a lagged response due to delayed recolonisation and the autumn model differentiating habitat loss and flow velocity-driven responses. The application of DEHLI and the principles which underlie it allow the effects of drought on instream habitats and invertebrates associated with short or long term weather patterns to be monitored, whilst also allowing the identification of specific locations where intervention via river restoration, or revision of existing abstraction licensing, may be required to increase resilience to the effect of anthropogenic activities exacerbated by climate change.     

山地河流浅滩深潭生境大型底栖动物群落比较研究——以重庆开县东河为例

浅滩和深潭是山地河流中常见的河流生境结构。2011年7月,在重庆开县东河上游双河口-杉木桥河段,选择21个浅滩和深潭,调查大型底栖动物,研究影响不同生境中底栖动物组成、分布和多样性的生态机理。结果表明:调查河段浅滩和深潭中大型底栖动物分别为31种和24种,密度分别为450.62 个/m²和86.24 个/m²,生物量分别为2.88 g/m²和0.55 g/m²。浅滩有指示种11种,即纹石蛾(Hydropsyche sp.)、假蜉(Iron sp.)、假二翅蜉(Pseudocloeon sp.)、舌石蛾(Glossosoma sp.)、高翔蜉(Epeorus sp.1)、背刺蜉(Notacanthurus sp.)、Heterocloeon sp、锯形蜉(Serratella sp.)、朝大蚊(Antocha sp.)、等蜉(Isonychia sp.)、溪颏蜉(Rhithrogena sp.)。深潭指示种仅蜉蝣(Ephemera sp.)和黑大蚊(Hexatoma sp.)两种。刮食者为两类生境的优势功能摄食类群。浅滩中滤食者和刮食者比例显著高于深潭,而收集者和捕食者显著低于深潭。两类生境中大型底栖动物群落结构差异显著。浅滩中大型底栖动物的密度、生物量、丰富度指数、Shannon-Wiener 指数、改进的Shannon-Wiener指数均明显高于深潭。受地貌形态、水力特征和冲淤变化规律影响的生境稳定性和异质性差异是导致大型底栖动物群落差异的主要原因。     

Ecological health of the Usuthu and Mbuluzi rivers in Swaziland based onselected biological indicators

Biological monitoring, using coliform bacteria and macroinvertebrate populations and diversity, was carried out monthly from August 2004 to January 2005 to determine the ecological health of the Usuthu and Mbuluzi rivers in Swaziland. Water temperature and pH were not significantly different between sites, but differed significantly between months. Bacterial species identified from both rivers were Escherichia coli, Klebsiella pneumoniae and Proteus vulgaris, with no significant differences in mean colony counts between the two rivers. Average colony counts were significantly different between months. A total of 926 macroinvertebrates, representing 28 families, were collected from both rivers and were significantly different between sites, rivers and months. Macroinvertebrate populations and diversity were negatively correlated with bacterial colony counts. Compliance with regulated water quality standards did not necessarily indicate acceptable water quality for biological communities, and thus there is a need for an integrated approach in water quality monitoring.     

Preliminary testing of River Habitat Survey features for the aims of the WFD hydro-morphological assessment: an overview from the STAR Project

The UK River Habitat Survey (RHS) method for the assessment of hydro-morphological features was applied within the EU STAR project simultaneously with the collection of biological data. A subset of data from 79 sites affected by hydro-morphological alteration and belonging to 7 different stream types was analysed. The different features recorded within RHS were evaluated separately considering the characteristics associated with banks, channel and riparian zone. Different scores were assigned to selected features representing hydro-morphological alteration and naturalness of habitat. The ability of the different compartments to represent the quality gradient of sites was investigated. In addition, the link between macroinvertebrate community and hydro-morphological data was investigated, directly relating indices and metrics calculated from taxa list collected in a site to scores assigned to the RHS features. The sections highly affected by morphological alteration were channel geometry and bank profile. Metrics showing the best correlation with the features selected were EPT taxa, ASPT and ICMi (Inter-calibration Common Metric index). Among the indices studied, the HQA score (Habitat Quality Assessment) apparently played the most important role in structuring biological communities and the lentic-lotic character of rivers was also important. Electronic supplementary material Electronic supplementary material is available for this article at and accessible for authorised users.     

Effects of dams and their environmental impacts on the genetic diversity and connectivity of freshwater mussel populations in Poyang Lake Basin,China

1. Habitat fragmentation is one of the main threats to biodiversity. Barriers to dispersal caused by anthropogenic habitat alteration may affect phylogeographic patterns in freshwater mussels. Knowledge of the phylogenetic and phylogeographic patterns of unionoids is vital to inform protection of their biodiversity.
2. Here, we assessed influences of dams and their environmental effects on the genetic diversity and population connectivity of a broadly distributed freshwater mussel, Nodularia douglasiae, in Poyang Lake Basin.
3. The results showed high genetic diversity in areas without dams and low genetic diversity in areas with dams. High genetic differentiation and low gene flow were found among the 11 populations. Genetic variation was significantly correlated with dissolved oxygen levels.
4. The observation of low genetic diversity in populations separated by dams indicated that those populations were subjected to genetic erosion and demographic decline because they are disconnected from other populations with higher diversity. High genetic differentiation and low gene flow among the 11 populations could be correlated with anthropogenic habitat alteration.
5. These results indicated that anthropogenic habitat alterations have led to the decline in freshwater mussel diversity. Therefore, we recommend maintaining favourable habitat conditions and connectivity of rivers or lakes, and strengthening study of life histories with host-test experiments to identify potential host fish species to strengthen the knowledge base underpinning freshwater mussel conservation.

     

Habitat and hydrology condition indices for the upper Mississippi,Missouri, and Ohio rivers

Habitat and hydrology indices were developed to assess the conditions in reaches of the impounded Mississippi river, the Fort Peck and Garrison reaches of the upper Missouri river, the Missouri National Recreational river (MNRR), the channelized lower Missouri river, and the Ohio river. Data were obtained from field sampling, air photo interpretation, and U.S. Geological Survey (USGS) hydrologic records. Habitat and hydrology attributes were incorporated into four habitat indices (channel complexity, substrate quality, littoral cover, and riparian condition) and one hydrology index. Construction of habitat indices for these very large rivers was complicated by a lack of previous research demonstrating methods for choosing and weighting the metrics used to compose these indices. Many habitat metrics used to assess habitat quality in small rivers proved irrelevant or impractical for assessing habitat quality in the upper Mississippi, Missouri, and Ohio rivers. In addition, these very large rivers, unlike smaller streams, were subject to physical and hydrological alterations due to channelization, revetment, levees, and dams. Because of the lack of proven indicators of habitat condition in very large rivers, we began with a large number of measures of natural and anthropogenic stress, eliminating only those metrics that failed tests of range, redundancy, and correlation with longitudinal position along the river. The lock and low-head dam sequences on the impounded Mississippi and Ohio influenced both hydrological patterns and the resident fish community, with conditions recovering with increased distance below dams, until hydrology was once again altered by impoundment from a downriver dam. Channel complexity and hydrology indices displayed the highest correlations with a multimetric fish index, possibly because these indices integrated habitat condition over a larger scale than the transect- and site-scaled littoral cover and riparian indices. Data limitations prevented the calculation of a littoral cover and a channel complexity index for the upper Missouri and Ohio rivers, respectively.     

Plant diversity and habitat structure affect tree growth,herbivory and natural enemies in shelterbelts

Shelterbelts have become a refuge and source of food for wildlife because of habitat loss in farmlands. However, effects of shelterbelt attributes such as plant diversity and habitat structure on different trophic levels within shelterbelts are unclear. Effects of shelterbelt woody plant diversity and habitat structure (lower vegetation strata, logs, litter and rocks) were measured on the growth and herbivory of Eucalyptus blakelyi saplings that were caged from birds, caged from birds and arthropods and un-caged. Arthropod diversity of E. blakelyi saplings and shelterbelts was evaluated. Height and stem diameter of saplings in all treatments was positively correlated with plant diversity. Habitat structure was negatively correlated with numbers of leaves on E. blakelyi saplings and positively correlated with herbivory, which was greater in saplings caged from birds. The overall abundance of arthropods inhabiting shelterbelts correlated positively with plant diversity, but negatively with habitat structure. Araneae and Formicidae were the most common taxa on E. blakelyi saplings and were more numerous on saplings caged from birds, suggesting an important role of these vertebrates as predators of shelterbelt arthropods.     

The invertebrate fauna of a physically modified urban river

The typical urban river is affected by various factors relating to water quality problems, physical habitat modification (for flood prevention) and flashy flows. These restrict macroinvertebrate biodiversity such that a few tolerant taxa may dominate and more sensitive organisms may be completely absent. This paper presents the findings of a year long, macroinvertebrate survey of an urban river catchment and investigates the effects of physical habitat modification on macroinvertebrates using various analytical tools. It is demonstrated that considerable variation in invertebrate species, abundance, diversity and tolerance exists between different urban rivers, sites on the same river and individual sites at different sampling times. Analysis of paired sites with similar water quality, but contrasting physical habitat, indicates that less modified sites support a slightly higher quality macroinvertebrate fauna (defined by biotic score and beta diversity) than heavily engineered sites. It is concluded that water quality is the primary limiting factor of invertebrate biodiversity in the heavily urbanized River Tame catchment. The removal of heavy engineering structures may facilitate improvements to invertebrate fauna in urban rivers only in conjunction with improvements to water quality.