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Understanding movement patterns and home range of rare species is challenging, especially aquatic fauna like fishes. The Sickle Darter Percina williamsi is a rare fish species endemic to the upper Tennessee River basin in eastern Tennessee, southwestern Virginia, and western North Carolina (USA). It has been listed as threatened by the states of Tennessee and Virginia and is being petitioned for federal listing under the United States Endangered Species Act. Little is known about the movement and home range of this species. A total of 8 Sickle Darters from the upper Emory River system were implanted with 8-mm PIT tags and released at the point of capture. The mean (± SD) total length and weight of all fish PIT tagged was 70.1 ± 3.4 mm and 3.08 ± 1.4 g. Movement of individuals was tracked every 2 weeks for 6 months (September–March) with a Biomark® HPR Plus reader and BP Plus portable antenna. Associated environmental data were collected throughout the study. Mean total effort for all the tracking events was 70 ± 39.4 min, mean catch-per-effort was 9.3 ± 6.6 (min/detection) and mean (± SE) detection was 69.5 ± 12%. Mean (± SD) distanced moved of all individuals throughout the study was 7.1 ± 4.5 m. Best sub-sets regressions modelling suggest that Sickle Darter movement is related to discharge (m/s3) at multiple temporal levels (1, 3, or 7-day). Home range for individuals varied in size. Median home range size was 157.5 (86.0–312.5) m2 and median (range) degree of overlap for estimated home range was 23.3 (6.2–34.0) %. The results from this study suggest that Sickle Darters exhibit strong site fidelity except when discharge is extremely high. Therefore, conservation measures that protect or attempt to reconnect fragmented habitats will need to factor in the low dispersal ability of this species. [ABSTRACT FROM AUTHOR]

Water abstraction modifies the environmental conditions of stream ecosystems, which can affect invertebrate assemblages by altering drift. We examined this issue with a before-after-control-impact design experiment in which we diverted 90% of the natural flow from a headwater stream. We measured flow-reduction effects on drift densities (animals/m3), total drift rates (animals leaving the reach per hour) and net balance of invertebrates entering or leaving the Impact reach. We also identified the specific taxa and traits that drove these responses. The sudden decrease in flow promoted a 12-fold increase in overall drift density at the Impact reach, which was primarily driven by filterers, shredders and taxa associated with fast velocities, such as simulids. By contrast, drift densities of other abundant taxa, such as Baetis, Esolus and chironomids, increased less than what could be expected from the magnitude of flow reduction. While drift rates remained unchanged after water abstraction, the Impact reach became a net invertebrate exporter indicating that many taxa drifted actively as a response to stressful conditions rather than passively, which would be reduced by water abstraction. Therefore, our results suggest that water abstraction influences drift, with potentially important consequences for the invertebrate assemblages and ecosystem processes further downstream. [ABSTRACT FROM AUTHOR]

The implementation of the Water Framework Directive has required intense research in applied aquatic ecology in Europe, and thus created challenges for data management in international research projects. In the project Waterbodies in Europe: Integrative Systems to assess Ecological status and Recovery (WISER), biological and environmental data from rivers, lakes, transitional and coastal waters in 26 European countries were collated. More than one million records of biological observations were stored in the project's central database, representing phytoplankton, macrophytes, macroalgae, angiosperms, phytobenthos, invertebrates and fish. The central database includes new data from the WISER field campaign in lakes and transitional/coastal waters during 2009-2010 (more than 6,000 biological samples from 58 waterbodies in 14 countries). The purpose of this paper is to provide an overview of the data collated within WISER, in order to facilitate future re-use of these data by other scientists. More specifically, the objectives are to (1) describe the data management in WISER, (2) describe the structure and content of the WISER central database and (3) share experiences and give recommendations for data management in large ecological research projects. [ABSTRACT FROM AUTHOR]

The EU-funded research project WISER ('Water bodies in Europe: Integrative Systems to assess Ecological status and Recovery') developed new assessment methods required by the EU Water Framework Directive (WFD) for lakes, coastal and transitional waters. WISER also addressed the recovery of biotic assemblages from degradation. The results are summarised in five key messages, supported by papers in this special issue and by WISER results published elsewhere: (1) Response to stress differs between organism groups, water types and stressors; a conceptual model is proposed summarising how the individual organism groups respond to different types of degradation in rivers, lakes, transitional and coastal waters. (2) The sources of uncertainty differ between BQEs and water types, leading to methodological suggestions on how to design WFD sampling programmes. (3) Results from about 300 current assessment methods indicate geographical variations in metrics but assessments are comparable at an aggregated level ('ecological status'). (4) Scale and time matter; restoration requires action at (sub)-basin levels and recovery may require decades. (5) Long-term trends require consideration; the effects of both degradation and restoration at the water body or river basin scales is increasingly superimposed by multiple stressors acting at large scales, in particular by climate change. [ABSTRACT FROM AUTHOR]

In ecological sciences, the role of metadata (i.e. key information about a dataset) to make existing datasets visible and discoverable has become increasingly important. Within the EU-funded WISER project (Water bodies in Europe: Integrative Systems to assess Ecological status and Recovery), we designed a metadatabase to allow scientists to find the optimal data for their analyses. An online questionnaire helped to collect metadata from the data providers and an online query tool () facilitated data evaluation. The WISER metadatabase currently holds information on 114 datasets (22 river, 71 lake, 1 general freshwater and 20 coastal/transitional datasets), which also can be accessed by external scientists. We evaluate if generally used metadata standards (e.g. Darwin Core, ISO 19115, CSDGM, EML) are suitable for such specific purposes as WISER and suggest at least the linkage with standard metadata fields. Furthermore, we discuss whether the simple metadata documentation is enough for others to reuse a dataset and why there is still reluctance to publish both metadata and primary research data (i.e. time and financial constraints, misuse of data, abandoning intellectual property rights). We emphasise that metadata publication has major advantages as it makes datasets detectable by other scientists and generally makes a scientist's work more visible. [ABSTRACT FROM AUTHOR]

Relationships between environmental variables, ecosystem metabolism, and benthos are not well understood in sub-arctic ecosystems. The goal of this study was to investigate environmental drivers of river ecosystem metabolism and macroinvertebrate density in a sub-arctic river. We estimated primary production and respiration rates, sampled benthic macroinvertebrates, and monitored light intensity, discharge rate, and nutrient concentrations in the Chena River, interior Alaska, over two summers. We employed Random Forests models to identify predictor variables for metabolism rates and benthic macroinvertebrate density and biomass, and calculated Spearman correlations between in-stream nutrient levels and metabolism rates. Models indicated that discharge and length of time between high water events were the most important factors measured for predicting metabolism rates. Discharge was the most important variable for predicting benthic macroinvertebrate density and biomass. Primary production rate peaked at intermediate discharge, respiration rate was lowest at the greatest time since last high water event, and benthic macroinvertebrate density was lowest at high discharge rates. The ratio of dissolved inorganic nitrogen to soluble reactive phosphorus ranged from 27:1 to 172:1. We found that discharge plays a key role in regulating stream ecosystem metabolism, but that low phosphorous levels also likely limit primary production in this sub-arctic stream. [ABSTRACT FROM AUTHOR]

One of the most striking features of the diatom Didymosphenia geminata, which has increased markedly in abundance in a number of countries in recent years, is the very large branched stalks. In order to help understanding their role, an ultrastructural study was carried out on two populations, one from a stream in northern England and the other from a river on Vancouver Island, Canada. In both cases, the main part of the stalk had a central reticulate core surrounded by an outer region with dense fibres. A longitudinal structure in the uppermost part of the stalk just under the collar surrounding the base of the cell may perhaps correspond to a tube. The structure of the septa formed where branches divide is also described. Phosphomonoesterase activity known to be present in the stalks was shown to occur in the inner peripheral layers of the stalks and especially in the collar area. The results show that stalks have a complex structure suggesting their importance for their phosphatase activity to overcome low inorganic phosphate concentrations. Their large surface may function in herbivory avoidance, a better exposure of cells to turbulent conditions to increase nutrient uptake, adsorption of limiting elements and gas exchange. [ABSTRACT FROM AUTHOR]

Intercalibration of ecological status class boundaries between member states is a requirement of the European Union's Water Framework Directive. Although a preliminary intercalibration of boundaries established for phytobenthos has been performed, a number of questions remain, including the extent to which variations in taxonomic concepts used in different member states influences the position of these boundaries. In this paper, the robustness of the diatom-based metrics used for intercalibration is assessed. Whilst use of genus-level identification led to a loss of ecological information, merging representatives of closely-related taxa has little effect on these metrics. Similarly, taxa that occur only rarely or never have high relative abundances in a dataset can also be ignored without the loss of ecological information. Similar results were obtained when modern taxonomic concepts were compared with concepts in use 80 years ago. Fine scale taxonomy may play a valuable role within member states; however, our results suggest that, at a continental scale, a simplified approach to diatom taxonomy should not affect intercalibration results. [ABSTRACT FROM AUTHOR]

Riverine habitats are vulnerable to a host of environmental stressors, many of which are increasing in frequency and intensity across the globe. Climate change is arguably the greatest threat on the horizon, with serious implications for freshwater food webs via alterations in thermal regimes, resource quality and availability, and hydrology. This will induce radical restructuring of many food webs, by altering the identity of nodes, the strength and patterning of interactions and consequently the dynamics and architecture of the trophic network as a whole. Although such effects are likely to be apparent globally, they are predicted to be especially rapid and dramatic in high altitude and latitude ecosystems, which represent 'sentinel systems'. The complex and subtle connections between members of a food web and potential synergistic interactions with other environmental stressors can lead to seemingly counterintuitive responses to perturbations that cannot be predicted from the traditional focus of studying individual species in isolation. In this review, we highlight the need for developing new network-based approaches to understand and predict the consequences of global change in running waters. [ABSTRACT FROM AUTHOR]

This article comprises a literature analysis of 41 river rehabilitation projects to assess the short-term (5 years) ability of indicator groups to demonstrate progress towards river rehabilitation goals. Positive indications were compared to land-use, river size, rehabilitation intervention and time. A questionnaire was developed to investigate river manager's interpretation of rehabilitation success and to assess their level of adherence to recommendations in the literature with regard to rehabilitation assessment on a conceptual level. A total of 54 responses were received from respondents based in Germany, The Netherlands and the United Kingdom. The results indicate that macroinvertebrate indicators, while widely used in assessing river rehabilitation efforts, exhibited a lower frequency of positive responses than most other indicator types in the short term. Conversely, terrestrial floodplain indicators exhibited the most frequent level of positive response for all ecological type indicators leading to recommendations for further investigations into their use for short-term monitoring. Assessment procedures recommended in literature are largely followed, illustrating the advances that have been made with regard to assessment planning. Indicator responses are influenced by scale factors, for example, land-use and river size, that are often not considered by rehabilitation managers. While an emphasis is placed on ecological, hydrological and morphological indicators in monitoring schemes, the socioeconomic perspective (emphasized in the literature as forming an integral part of the river system) is neglected. [ABSTRACT FROM AUTHOR]

We examined abundances of fishes by ecological categories for variation with time (years) and longitudinal river distance (km) in the Wabash River, a large US Midwestern river. An ordination resulted in significant correlations with time for an axis that represented increases in surface-feeding invertivores and species that prefer sand substrates. We found increased abundances of planktivores and species with high tolerance to silt in downstream river sites. We found significant changes in abundance for the majority of ecological categories in comparisons of upstream–downstream locations. There was a general decrease in abundances of taxa in ecological categories that tend to inhabit upstream reaches: species that prefer rubble substrates, inhabit fast, and moderate current velocity habitats, and that have low silt tolerance with time. These abundance changes suggest that the upstream river experienced increased sedimentation during 1974–1998. The use of ecological categories provided information for likely habitat changes, such as increased sedimentation, that were not apparent in previous taxonomic analyses. We suggest that combinations of anthropogenic impacts including hydrologic alterations and agricultural activities in the Wabash River resulted in ecosystem changes and subsequent changes in abundance of fishes by ecological categories. [ABSTRACT FROM AUTHOR]

The structure and dynamics of fish communities were characterized by richness, abundance, diversity and stability, during high-water and low-water periods. These analyses were performed on data from the flood zone of four streams in the lower Purus River, in the Brazilian Amazon. A total of 188 species of fish were collected, distributed among 29 families and eight orders. The statistical test showed a difference in community diversity between periods. The high-water period showed higher evenness in comparison to the low-water season. The low-water period was marked by high species abundance. A great variation in community composition between the flood and low-water periods was encountered. The adjustments for species abundance models suggested that stochastic events structure the communities. Most of the species showed a temporal variation of abundance indicating low community stability. Changes in the physico-chemical conditions of the water caused by the seasonal hydrological regime may be influencing the structuring of the fish communities. [ABSTRACT FROM AUTHOR]

The EU’s Water Framework Directive (WFD) in particular makes good use of riverine biota—including fish—as ecological indicators of river integrity. However, it is also important to examine when our indicators fail to serve the purpose for which they were originally intended: to consistently and reliably describe the quality of the environment. We argue that in the Czech Republic (and probably several other European countries), the use of adult fish as ecological indicators often fails to fulfill these purposes for several reasons, especially when fish are stocked in natural waters, for practical considerations during field sampling, and problems with public relations. The ecological quality of running waters sensu WFD is usually assessed on the basis of the adult fish assemblage. The aim of this study is to describe disadvantages of monitoring river integrity using adult fish in Czech Republic, which has regular and widespread stocking of more than one-third of fish species present in running waters and to suggest the alternative strategy of young-of-the-year (YOY) fish monitoring for assessing river ecological quality with the ability to provide a sensitive response to water quality and habitat structure regardless of the effect of stocking or river size. We conclude that even though YOY sampling is often a more logical and practical approach to water quality monitoring under specific conditions, no method is perfect and caution should be taken. For example, YOY can have high annual variability in density and higher sensitivity to summer flood events than adults. The suitable time for sampling YOY fishes in late summer is much shorter than for the adult fish community, and therefore must be considered when designing a successful monitoring strategy. Monitoring of YOY fishes does not provide direct information about age structure of fish populations, which is required by WFD. YOY sampling is a useful—albeit imperfect—method for providing a sensitive response to ecological status of rivers, especially under specific stocking conditions. [ABSTRACT FROM AUTHOR]

The stream macroalgal community is controlled by heterogeneous physical, chemical, and biological factors related with multiple spatial and temporal scales; however, the mechanisms that explain diversity and distribution are scarcely known. The present investigation was conducted to characterize the macroalgal community structure and spatial and temporal distribution and to recognize biogeographic affinities with mountain streams from other regions. Habitat characteristics, abundance, and diversity were investigated in four mountain streams of Valle de Bravo Basin, central Mexico, during two annual cycles. Sampling of visible benthic growths was collected in the most contrasting parts of the year. Physicochemical parameters were recorded in situ at each site and the main ions and nutriments were evaluated for every collection. Statistical analysis between dates was assessed with one-way analysis of variance (ANOVA) and Canonical Correspondence Analysis (CCA). Observed richness average was four species per site and the high abundance of Phormidium interruptum, Nostoc parmelioides, Paralemanea mexicana, Batrachospermum gelatinosum, Sirodotia suecica, Cladophora glomerata, and Prasiola mexicana correlated with cold dry season, high current velocity, and a major size substrate. Valle de Bravo streams can be viewed as a habitat subjected to moderated disturbance, mainly due to the effects of seasonal changes in rainfall contrary to torrents expected of tropical regions. The seasonal patterns of macroalgal communities in Valle de Bravo basin were typically characterized by two distinct periods essentially determined by the rainfall regime and related to temperature, and can be viewed as habitats subjected to moderate disturbance according to intermediate disturbance hypothesis. The distribution species pattern registered suggests a group of temperate species frequently found in mountain regions of the Mexican Volcanic Belt and temperate eastern region of North America and may indicate a possible biogeographic connection with the Neartic region with similar environmental requirements. [ABSTRACT FROM AUTHOR]

Diatoms have been routinely used to monitor the ecological status of French rivers. Since 2000, this monitoring has been carried out to comply with the Water Framework Directive. Ecoregions corresponding to the aquatic fauna and flora of rivers were originally defined on the basis of physical descriptors, designated “hydro-ecoregions” in France. Since, they have been simplified into diato-ecoregions for diatoms. In this study, data sets for benthic diatoms from rivers in north-eastern France were used to identify four main groups of diatom assemblages. The first such assemblage is found in small rivers with crystalline geologies in mountainous massifs with neutral to slightly acidic pH. The second assemblage occurs in small rivers flowing on limestone in lowland regions with an alkaline pH. The third corresponds to the assemblage found in large rivers in limestone lowland regions, and the fourth in highly mineralized rivers with high levels of chloride. Within each of these main assemblages, several communities have been characterized corresponding to different levels of pollution: from pristine to highly polluted. Multivariate analysis showed that the underlying geology was the main factor structuring the diatom assemblages, followed by the pollution level. River size had little impact on diatoms. Statistical tests showed that diato-ecoregions provided little information about diatom assemblages in the studied region, whereas there was a close correlation between diatoms and hydro-ecoregions. Nevertheless, these hydro-ecoregions did not account for the diatom assemblages in the highly mineralized rivers. These ecoregions could be further improved by merging the hydro-ecoregions of the crystalline mountainous massifs, all of which shared the same diatom assemblages. [ABSTRACT FROM AUTHOR]

This study determined the relative influences of environmental variation versus spatial autocorrelation on benthic macroinvertebrate community composition of temperate headwater streams. We enumerated fauna in riffle zones of 23 separate (i.e., not tributaries to each other) but closely grouped from first- to third-order woodland streams surrounding Zoar Valley Canyon, western New York State, USA, during spring, summer, and fall of 2006. Watershed geomorphology (stream order, catchment area, and forest cover) and semi-quantitative habitat characteristics, the latter of which were incorporated into a Qualitative Habitat Evaluation Index (QHEI), were also recorded for each stream. Non-metric Multidimensional Scaling (NMDS) ordination was used to establish patterns of biotic similarity among these streams. Matrices of biological and environmental Euclidean distances were constructed for all between-stream pairings. Additionally, a between-stream spatial matrix was constructed based on global position system coordinates of sampling sites. Non-significant partial Mantel coefficients indicated that biological distances were uncorrelated with spatial distances both among all 23 study streams and among 12 first-order streams only. In contrast, biological distances were positively correlated with environmental distances ( rM = 0.375 and 0.289 for all streams and for first-order streams only, respectively; P values < 0.05). Environmental and spatial distances were uncorrelated (partial Mantel P values > 0.05), indicating that the measured environmental characteristics were not spatially structured. Each of the geomorphological and habitat variables was statistically associated with NMDS community composition axes (stepwise multiple regression, one-factor MANOVA). These results suggest that environmental filters and niche-based species sorting may operate here between separate streams, and that study sites appear to be effectively insular in their biota despite close physical proximity. [ABSTRACT FROM AUTHOR]

The macrozoobenthos colonization process on artificial substrata in lotic environments was evaluated. Two seasonal periods, autumn–winter and spring–summer, of a relatively undisturbed fluvial system, the Estero Nonguén (VIII Region, Chile), have been studied. Five stations, two in riffles and three on sandy bottoms, extending from a head water stream to 5 km down river, were sampled. For all stations and for each season the results were as follows: (a) 32% of the total number of taxa found in this study colonized the artificial substrata on the first day of exposure, (b) the taxa that colonized sandy bottoms were typical for riffle, (c) the colonization process showed the same abundance, specific and cumulative richness and diversity patterns over time, and (d) equilibrium was reached approximately 2 weeks after initial exposure. This suggests that “Estero Nonguén” stream presents a nearly pristine condition and can be considered as a reference site to carry out biodiversity and ecosystem functionality studies, and giving information on time recovery for sectors previously disturbed. [ABSTRACT FROM AUTHOR]

Previous studies on recovery in hyporheic communities have found that communities rapidly return to pre-disturbance levels. However, most of these studies have concentrated on small floods or ones with short return periods. I studied the impact of a large 1 in 6 year flood on the hyporheic community at 2 sites in the Hunter River, a large coastal river in New South Wales with a mean daily flow of 15 m3 s−1. The flood peaked at 1270 m3 s−1 and afterwards invertebrate densities at the 2 sites were 83 and 67% less than they were before. Recovery to pre-flood densities was slow but was aided by increases in the oligochaete and cyclopoid populations. At Site 1, there was a boom in oligochaete and cyclopoid numbers 61 d after the flood, but the communities resumed their pre-flood densities by Day 139. Recovery at Site 2 took 139 d. Most groundwater taxa (stygobites) living in the hyporheic zone did not recover from the disturbance when compared to non-stygobites. Apart from Microturbellaria and the harpacticoid Parastenocaris sp., numbers of all stygobite taxa continued to decline after the flood, becoming absent after 61 d. The poor recovery of stygobites is probably due to their adaptations for survival in the relatively stable groundwater environment. This study shows that hyporheic communities are sensitive to large bed-moving floods and supports the hypothesis that ecotonal species with a strong affinity to one ecosystem can be poor at recovering from disturbances that occur in an adjacent ecosystem. [ABSTRACT FROM AUTHOR]

The main results of the STAR project on the intercalibration of boundaries of European assessment systems and comparison between assessment methods are summarized here. The main findings are outlined in the context of the Water Framework Directive that requires reliable instructions to be set up on how to use and harmonise assessment systems and methods for European rivers. The main papers published on these subjects by STAR partners are reviewed, with focus on major questions addressed and approaches used for investigation. The need for broad coverage of geographic ranges and pressure gradients, together with the goal of providing outcomes appropriate to the effective application of the WFD are emphasized. Extensive datasets from a wide range of countries, stream types and sites and a large number of methods, metrics and approaches are compared and tested and various cross-cutting themes emerged. Among these, the value of the use of benchmarking systems for comparison and intercalibration is highlighted. Two ways of looking for comparability of assessment systems results were analyzed: a) by adopting identical sampling techniques across Europe and b) by harmonizing the classification results of the national assessment systems. In addition, the need, in the intercalibration process, for a proper definition of the criteria for reference conditions is underlined. This is because their imprecision now represents one of the major weaknesses of the whole intercalibration process. Direct and indirect approaches to intercalibration are considered and commented on for their potential use in distinct circumstances. Finally, the use common metrics for the intercalibration process, which make comparability across Europe valid, is tested and indeed encouraged. [ABSTRACT FROM AUTHOR]

The aim of the intercalibration exercise presently performed by the EU is to identify and resolve significant inconsistencies between the ecological quality classifications of EU Member States and the normative definitions of the EU Water Framework Directive. Based on benthic macroinvertebrate data of two European stream types (small siliceous mountain streams and medium-sized lowland streams in Central and Western Europe) we correlated the indices of 10 river quality assessment methods (ASPT, BMWP, DSFI, German Multimetric Index, Saprobic Indices) applied in Austria, Czech Republic, Denmark, Germany, Poland, Slovak Republic, Sweden and United Kingdom. National class boundaries were compared via regression analysis. Assessment methods of the same type (Saprobic Indices, BMWP/ASPT scores) showed best correlation results ( R 2>0.7). The good quality status boundaries of the national methods deviated up to 25%; thus indicating the necessity to harmonize the national classification schemes. Prerequisites of the presented intercalibration approach are (1) a sufficiently large and consistent dataset representative of the respective common intercalibration types and (2) agreement on common type specific reference conditions. [ABSTRACT FROM AUTHOR]

The results of four macrophyte assessment methods (French Indice Biologique Macrophytique en Rivière, German Reference Index, British Mean Trophic Rank and Dutch Macrophyte Score) were compared, based on plant survey data of medium-sized lowland streams in Central Europe. To intercalibrate the good quality class boundaries two alternative methods were applied: direct comparison and the use of “common metrics”. While the French and British methods were highly related ( R 2>0.75), the German RI showed less (0.20< R 2<0.55) and the Dutch DMS least correlation ( R 2<0.10) with other methods. Of 70 macrophyte metrics tested only Ellenberg_N was considerably related to three of the national assessment methods, thus representing a potential common metric for intercalibration. Comparison of quality class boundaries via regression analysis using both intercalibration approaches revealed major differences between classifications of the French, German and British methods, which are, in addition, related in a nonlinear way. [ABSTRACT FROM AUTHOR]

The impact of altering hydro-morphology on three macrophyte community types was investigated at 107 European stream sites. Sites were surveyed using standard macrophyte and habitat survey techniques (Mean Trophic Rank Methodology and River Habitat Survey respectively). Principal Components Analysis shows the macrophyte community of upland streams live in a more structurally diverse physical habitat than lowland communities. Variables representing the homogeneity and diversity of the physical environment were used to successfully separate un-impacted from impacted sites, e.g. homogeneity of depth and substrate increased with decreasing quality class for lowland sites (ANOVA p < 0.05). Macrophyte attribute groups and structural metrics such as species richness were successfully linked to hydro-morphological variables indicative of impact. Most links were specific to each macrophyte community type, e.g., the attribute group liverworts, mosses and lichens decreased in abundance with increasing homogeneity of depth and decreasing substrate size at lowland sites but not at upland sites. Elodea canadensis, Sparganium emersum and Potamogeton crispus were indicative of impacted lowland sites. Many of the indicator species are also known to be tolerant to other forms of impact. The potential for a macrophyte tool indicative of hydro-morphological impact is discussed. It is concluded one could be constructed by combining indicator species and metrics such as species richness and evenness. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Successful stream restoration requires the setting of appropriate goals and an ability to measure restoration success using quantitative ecological indicators. At present, a dichotomy exists between the setting of restoration goals to enhance ecosystem ‘processes’ or ‘functions’ such as sustainability, and measuring the success of these goals using ‘patterns’ or ‘structural’ ecosystem attributes. The presence of a structural facade may be no indication of a viable ecosystem as this requires evaluation of whether key ecosystem processes have been restored and whether the system is ecologically sustainable. We briefly discuss the benefits and drawbacks associated with setting restoration goals and measuring their success based on ecosystem patterns and processes. Two case studies are provided based on measurements of biofilm chlorophyll a and Dissolved Organic Carbon (DOC) to debunk the myth that these structural variables can be used as surrogates for ecosystem processes of productivity and respiration in rivers. We suggest that the discipline of restoration ecology will benefit and grow from a greater appreciation of the functional role of biological communities within stream ecosystems, and from targeting some restoration towards the re-establishment of structurally significant species and functionally significant processes. This approach to stream restoration with a well-founded conceptual base and defined scientific and management goals should expand our knowledge of stream function and contribute to the effective restoration of stream systems. [ABSTRACT FROM AUTHOR]

From their introduction in the beginning of the 19th century in the Lez river at Montpellier, the American Ludwigia have, progressively, colonized the whole of France. In spite of their real nuisance for natural habitats, these ornamental hydrophytes are still for sale. The management of these invasive species requires their precise identification, but this appears to be extremely complex. A morphological and cytogenetic study allowed to confirm the presence of two different taxa in France, and the absence of hybrids in the mixed zones that were monitored. The diploids (2 n = 16) correspond to L. peploides subsp. montevidensis (Spreng.) Raven, and the decaploids (2 n = 80) to L. grandiflora subsp. hexapetala (Hook. & Arn.) Nesom & Kartesz. The diploids colonize especially the Mediterranean region (except the Southeastern part), while the polyploids predominate throughout the other regions. Both taxa exhibit an intense vegetative growth, however they have a distinct breeding system: the self-compatible diploids were always found very fructiferous, whereas the self-incompatible polyploids were often observed as sterile. The breeding system difference could explain the substitution of L. grandiflora (first wave of invasion in the 19th century) by L. peploides, in the 20th century, in the southern part of France. [ABSTRACT FROM AUTHOR]

This case study sought to examine how temporal variability in hydrological and hydraulic conditions might affect the feeding opportunities of juvenile Atlantic salmon in two hydrologically contrasting years of 2002 and 2003, which were characterised by high and low flows respectively. Firstly, measures of hydraulic influence were calculated to define what might be ecologically meaningful disturbance periods during high flows. Secondly, for identifying such periods, the parameter Critical Displacement Velocity (CDV) was derived from a river discharge time series as a first approximation of the amount of time in two hydrologically extreme years when fish foraging strategies for specific age classes of juvenile Atlantic salmon ( Salmo salar) might be disrupted by flows. The CDV estimates the threshold velocity above which juvenile salmon are unable to hold station and it is dependent upon fish size and stream temperature. In the wet year 2002, the CDV was exceeded on 18% and 21% of days for 0+ and 1+ fish respectively. In 2003 these respective numbers fell to 6% and 15%. The data suggest that hydrological conditions during certain times of the year have the potential to affect foraging behaviour. This in turn might have implications for recruitment and growth rates for juvenile salmon in upland streams. [ABSTRACT FROM AUTHOR]

Hierarchy theory provides a conceptual framework for understanding the influence of differently scaled processes on the structure of stream communities. Channel form, instream habitat, and stream communities appear to be hierarchically related, but the strength of the relationships among all components of this hypothesized hierarchy have not been examined. We sampled channel form, instream habitat, fishes, and macroinvertebrates in a channelized stream in Mississippi and Alabama to examine the hypothesis that a hierarchical relationship exists among channel form, instream habitat, and stream communities. Instream habitat, fishes, and macroinvertebrates were sampled in May, July, and September 2000. Measurements of channel form were obtained in July 2000. Mantel tests, multiple regressions, and correlation analyses were used to assess strength of the relationships among channel form, instream habitat, and stream communities. Positive correlations were observed between channel form and instream habitat, and correlations observed between these factors were the greatest observed in our study. Overall, fish and macroinvertebrate communities exhibited stronger relationships with instream habitat than with channel form. Species richness, evenness, and abundance tended to exhibit greater correlations with instream habitat, while species composition had greater correlations with channel form. We concluded that channel form, instream habitat, and stream communities were hierarchically related. [ABSTRACT FROM AUTHOR]

Modifications and use of Karr’s Index of Biotic Integrity (IBI) for assessing the effects of anthropogenic impacts to aquatic ecosystems have typically occurred using data collected at the macro scale. However, some non-point sources of habitat degradation occur at small scales. One possible source of perturbation to fish habitat in boreal rivers is the application of rip rap shoreline armouring in human use areas. In this study we assess the use of IBI in a small scale setting and discuss the potential impact of rip rap shoreline armouring. We captured small and juvenile fishes weekly during 2002–2003 from 12 sample sites within the littoral zone of a human use area using a modified beach seine. Principal component analysis (PCA) was performed on the data to examine the relationship between species composition and IBI scores. We also performed PCA on the IBI metrics to assess our modifications. The IBI method produced higher scores for armoured sites than for unarmoured sites. We found a strong rank order correlation (Spearman’s ρ > 0.93; p < 0.001) between the modified IBI scores and the first principal component, suggesting that Karr’s original empirically-based IBI is strongly linked to species composition. We found a high degree of redundancy between the metrics of the IBI that validate our modifications. These results suggest that IBI can be a suitable method for assessing non-point impacts from within a small study area. Our results also indicate that fish habitat from rip rap armoured sites within the test area had consistently higher IBI scores that unarmoured sites. [ABSTRACT FROM AUTHOR]

The loss of feeding areas may pose a threat to many wintering waders because increased competition arising from reduced foraging space may force birds either to emigrate or to die. This has been demonstrated to occur in northwest European estuaries, but virtually no studies have been performed in the estuaries of southern Europe, where the loss of supratidal habitats (salines and saltmarshes), rather than intertidal habitats, are currently the main threat to waders’ habitats. If these habitats are lost, waders may be forced to move to the intertidal mudflats, perhaps increasing competition between individuals and ultimately leading to starvation or emigration. We tested this hypothesis in the Mondego estuary, a small estuary on Portugal’s west coast, which is presently under heavy human pressure. We used indirect methods to test for the occurrence of both components of intra-specific competition: interference and prey depletion. We found no evidence that either interference or depletion competition was occurring at present, either on the mudflats or in the salines. Overall, the results suggest that the intertidal mudflats may still be able to accommodate birds displaced from the destroyed supratidal salines, but modelling is required to predict the effect that the combined loss of feeding area and foraging time that this would entail would have on their fitness, and thus numbers. [ABSTRACT FROM AUTHOR]

The main objective of the European Union (EU) funded project AQEM1was to develop a framework of an assessment system for streams in Europe based on benthic macroinvertebrates that fulfils the requirements of the EU Water Framework Directive. Initial assessment methods for 28 European stream types and more generally applicable tools for stream biomonitoring in Europe were generated. The development of the system was based on a newly collected data set covering stream types in Austria, the Czech Republic, Germany, Greece, Italy, The Netherlands, Portugal and Sweden. Altogether, 901 benthic invertebrate samples were taken using a standardised multi-habitat sampling procedure and a large number of parameters describing the streams and their catchments was recorded for all sampling sites. From the stream and catchment characteristics measures of stress were derived. A large number of metrics was tested independently for each of the stream types, to identify the response of each metric to degradation of a site. This process resulted in up to 18 core metrics for the individual stream types, which were combined into a different multimetric index in each country. The multimetric AQEM assessment system is used to classify a stream stretch into an Ecological Quality Class ranging from 5 (high quality) to 1 (bad quality) and often provides information on the possible causes of degradation. AQEM provides a taxa list of 9557 European macroinvertebrate taxa with associated autecological information, a software package for performing all the calculations necessary for applying the multimetric AQEM assessment system and a manual describing all aspects of the application of the system from site selection to data interpretation. [ABSTRACT FROM AUTHOR]

We developed and tested an `electronic subsampling technique' with benthic invertebrate samples taken in three German stream types to investigate, how strongly the number of individuals analysed influences the results. For each of 152 samples (`reference samples') 100 subsamples of the sizes 100, 200, 300, 500 and 700 individuals were generated randomly. To evaluate subsample deviation from the reference sample 45 metrics were calculated. In general, the variability of metric results increases with decreasing subsample size. Individual metrics show different sensitivity to decreasing subsample size. Three of the metrics tested (German Saprobic Index, German Fauna Index and Ecological Quality Index using Macroinvertebrates) are part of the German AQEM assessment system, for which they are transferred into quality classes. More than 40% of the 100-individuals subsamples are classified into a different quality class compared to the reference samples, but less than 20% for 700-individual subsamples. A certainty >20% is obtained with a subsample size of 300 individuals in lowland streams, whereas 700 individuals are needed to achieve the same level of confidence in mountain streams. Metrics, which rely on absolute abundances or abundance classes (e.g. BMWP, number of taxa) show higher sensitivity to a changing number of individuals than metrics, which depend on relative abundances (e.g. [%] Lithal preferences, [%] of Gatherers/collectors). Thus, the reliability of the metrics is related to subsample size, stream type and metric type. [ABSTRACT FROM AUTHOR]

The European Water Framework Directive stipulates that Member States have to assess the ecological status of a water body by comparing the present to the expected reference condition. In the AQEM project participating countries used the criteria from the Water Framework Directive to select reference sites for each stream type. The purpose of this study was to evaluate the suitability of these criteria and to validate the reference conditions chosen, by comparing the classification of sites before analysis with the final assessment of the sites using the assessment system which was developed within the AQEM project. Our study showed that not all criteria for reference conditions could be met for all stream types. This implies that `true' reference sites could not be selected for all stream types within the AQEM project. In our study, the differences between ecoregions, countries, and stream types were interpreted in terms of human impact. Validation of reference conditions showed differences between classification of sites as reference sites based on criteria to be used in the field and directly interpreting environmental or biological data and the result of the final assessment system. In some countries it was not possible to select reference conditions, because most of the a priori criteria were met. For example, reference conditions for Dutch stream types were established using historical data and predictions based on data from other geographical regions. Using data from adjacent countries appeared to be a feasible method for establishing reference conditions. Reference sites taken from other geographical areas represented a higher ecological quality than the Dutch sites of good ecological quality. However, metric results showed a large overlap between good and high ecological status. Historical information, on the other hand, was not found to be useful in metric calculations because of the confounding differences in sampling methods. One strong advantage of using historical information is that rare species that are locally extinct but still occur in the same stream type in other geographical areas can be added to the expected reference conditions. When and which methods can be used for establishing reference conditions is illustrated in a decision tree. [ABSTRACT FROM AUTHOR]

This study describes the development of a macroinvertebrate based multimetric index for two stream types, fast and slow running streams, in the Netherlands within the AQEM project. Existing macroinvertebrate data (949 samples) were collected from these stream types from all over the Netherlands. All sites received a ecological quality (post-)classification ranging from 1 (bad status) to 4 (good status) based on biotic and abiotic variables, using a combination of multivariate analysis and expert-judgement. A number of bioassessment metrics was tested for both stream types (fast and slow running streams) to examine their power to discriminate between streams of different ecological quality within each stream type. A metric was selected for inclusion in the final multimetric index when there was no overlap of the 25th and 75th percentile between one (or more) ecological quality class(es). Out of all metrics tested, none could distinguish between all four ecological quality classes without overlap of the 25th and 75th percentile between one or more of the classes. Instead, metrics were selected that could distinguish between one (or more) ecological quality class(es) and all others. Finally, 10 metrics were selected for the assessment of slow running streams and 11 metrics for the assessment of fast running streams. Class boundaries were established, to make the assignment of scores to the individual metrics possible. The class boundaries were set at the 25th and/or 75th percentile of the individual metric values. The individual metrics were combined into a multimetric index. Calibration showed that 67% of the samples from slow running streams and 65% of the samples from fast running streams were classified in accordance to their post-classification. In total, only 8% of the samples differed more than one quality class from the post-classification. The multimetric index was validated with data collected in the Netherlands from 82 sites for the purpose of the AQEM project. Validation showed that 54% of the streams were classified correctly. [ABSTRACT FROM AUTHOR]

A sampling programme was developed in three stream types, of siliceous geology, from the south of Portugal (small and mid-sized lowland streams and small-sized median altitude streams). The samples were taken according to the AQEM site protocol procedure, keeping transport and depositional habitats samples separated. In each stream type, at least 13 sites were studied over a gradient of organic pollution (pre-classification). The benthic macroinvertebrates were identified to the lowest possible taxonomic level. A Detrended Correspondence Analysis of macroinvertebrate communities identified a gradient of organic pollution strongly related to the first axis. This ordination allowed the establishment of classes of organic pollution using the Kmeans software (post-classification). Metrics based on the macroinvertebrate communities (tolerance, richness, composition and trophic structure) were computed and tested for correlation with the gradient of organic pollution (first axis of DCA). Most of the selected metrics were able to discriminate the four quality classes (high, good, moderate and poor) of ecological status. A multimetric index, integrating ASPT′ index, Trichoptera families and percentage of Gasteropoda, Oligochaeta and Diptera, is proposed to assess the ecological status of Portuguese southern siliceous basins. [ABSTRACT FROM AUTHOR]

Our study attempted a new approach to biological assessment in Germany that would comply with the requirements of the European Union Water Framework Directive. We developed a multimetric index for use throughout Germany, based on the macrozoobenthos and devised along the guidelines formulated by Karr & Chu (1999). The index contains twelve measures, chosen for their discriminatory power in assessing general impairment as well as specific stressors (e.g., impoundments, acidification, organic or chemical pollution), the inclusion of all meaningful ecological metric categories, interrelationship as low as possible and the feasibility of using them in all geographic stream classes of Germany. Due to the availability of data over time the method was developed in three steps. In step 1 we studied the stressor specific response of biological attributes to additional stress by comparing each of 162 sites impaired by a known factor with a nearby site, which was morphologically comparable, but impaired to a lesser extent. The resulting list of 17 candidate metrics for a multimetric index was validated in step 2 using a set of model data from our own investigations. This step included data from not or minimally disturbed reference sites and the design of a five-class-scale of human impact to permit the use of dose-response curves, but no differentiation of stream types. The multimetric index IBI 12 was developed using dose-response curves, correlation coefficients and graphical analysis. The index was improved in the third step, calculations for this based on a dataset containing about 4000 macrozoobentos samples from over 900 streams and rivers in Germany, collected by water management authorities and researchers. The final version of the method uses type specific reference conditions, but the same set of 12 metrics for all stream types. This new IBI 12 is suitable to fulfil the requirements of the EU Water Framework Directive. It correlates with a Spearman's R of 0.76 with the general state of impairment for every stream type, and a Spearman's R between 0.6 and 0.87 with the most important specific stressors like sewage or morphological degradation. It proved to correlate higher with those stressors than any single index as yet used in Germany. The stressor specific analysis also substantiated that no single metric was really stressor specific with the exception of an acidity index. Even the well established Saprobic indices responded quite well to other stressors besides organic pollution. The results suggest that a separate assessment of specific stressors might be only possible by analysing the reaction pattern of an array of metrics. Further improvement of the index could be achieved by advances in stream typology and the reference conditions, as well as by a higher degree of standardisation to decrease the scatter caused by variations in sampling season, methodology and determination level. [ABSTRACT FROM AUTHOR]

The generalization of ecological results from temporary streams needs the study of those ecosystems across a broad scale of running waters, covering the geographical ecological constraints involved (e.g., precipitation, temperature and geology). For the particular situation of Mediterranean streams in Southern Europe, high changes in water level, with unpredicting flood events, represent an important factor determining the structure and function of Mediterranean streams. This variability, inducing accentuated changes in the macroinvertebrate community, tends to influence the assessment methodologies. A set of metrics commonly used in Europe to assess organic degradation (Shannon–Wiener index, evenness, richness, BBI, IBE, BMWP′, ASPT′, DSFI, EPT, number of Trichoptera families, percentage of Gasteropoda, Oligochaeta and Diptera) and a multimetric index (IM9) developed to assess organic degradation in southern siliceous Portuguese basins were tested to evaluate quality at two contrasting sites (one unimpaired and another impaired by an identified point source of pollution). The multimetric index (IM9) composed by: ASPT′ (average score per taxon); GOLD (one minus percentage of Gasteropoda, Oligochaeta and Diptera); and TRICF (number of Trichoptera families), was the most suitable assessment methodology. IM9 presented a quite stable temporal pattern from February in late winter until June in early summer, even under the effect of episodic floods. A stepwise regression showed that most of tested metrics were significantly related to environmental variables (soluble reactive phosphorous, dissolved inorganic nitrogen and dissolved oxygen). Only richness, IBE and BMWP′ were not significantly influenced by environmental variables. Future research must be done covering the complete gradient of organic degradation, including the extension of multimetric assessment methodologies to temporary streams located in other regions under different geological and climatic conditions. [ABSTRACT FROM AUTHOR]

We investigated four stream types in four different bioregions, classified by catchment area and altitude, and stressed by different degrees of organic pollution and habitat alteration. We examined a macro-invertebrate based multimetric approach for Austrian rivers as a potential assessment method within the European Water Framework Directive. Benthic macro-invertebrate data (100 samples including reference sites) were used to develop a multimetric index for each stream type and targeted stressors. Sites were pre-classified based on physical, chemical, and land use criteria into five ecological quality classes. More than 200 biological metrics were tested for their sensitivity to the targeted stressors, their spatial and temporal variability and their ability to discriminate between different types and degrees of stress. Metrics for index development were selected to reflect different levels of information including ecosystem, community, and individual levels (Karr, 1991; Barbour et al., 1995; Gerritsen, 1995). Combinations of metrics were selected to distinguish best between non or slightly impaired and stressed sites (evaluated by calculating discrimination efficiency values and power analysis). The resulting four indices comprised seven to nine metrics from five to seven metric categories, and distinguished reference/slightly disturbed sites from stressed sites with close to 100% efficiency. The indices can form the basis for stressor-specific assessment of stream condition. [ABSTRACT FROM AUTHOR]

The present study aims to investigate whether taxa with a small distribution range or taxa with low abundances indicate specific habitats or a high ecological quality and what the effect is if these taxa are excluded from ecological assessment. We compared autecological features between stream dwelling taxa with a mean abundance >5 individuals per sample and a mean abundance \le5 individuals per sample as well as between taxa with a small distribution range and taxa with a large distribution range. The number of rare taxa (either with a small distribution range or with low abundances) in a sample was related to the ecological quality classes. To test the effect of exclusion of rare taxa we constructed 8 data sets all including 142 samples of Dutch lowland streams. From each data set we stepwise excluded taxa that had low abundances or taxa that were known to be restricted in their distribution range. With help of the AQEM assessment software we calculated the final ecological quality classes and the metrics that were included in the multimetric for the original data and the 8 selected data sets. Autecological features of the taxa within the different selections showed that taxa with small distribution ranges were often running water taxa, living on stones and gravel and indicating oligosaprobic water conditions in contrast to taxa that had a large distribution range. There were only small differences between taxa with low and high abundances. However, current velocity preference was lower for taxa with abundance \le5 individuals per sample, saprobic values were higher and scores for typical stream habitats, such as lithal, psammal and akal were lower compared to high abundant taxa. If taxa with low abundances were excluded a higher ecological quality class was achieved in most cases, while excluding taxa with a small distribution range resulted in lower ecological quality classes. In conclusion, excluding taxa with a small distribution range led to worse ecological quality classes because these taxa have special autecological features that often indicate natural streams. On the other hand, excluding taxa with low abundances resulted in higher ecological quality classes because these taxa indicate more disturbed situations and because the number of taxa per sample was strongly reduced. Although the documentation of rare taxa (either with low abundances or with small distribution ranges) is often time and cost-intensive regarding field work, laboratory work, data processing, and analyses, the indicative power of these taxa for natural circumstances is essential and therefore rare taxa should be included in ecological assessment studies. [ABSTRACT FROM AUTHOR]

In accordance with the aims of the E.U. funded AQEM Project, an assessment system module based on aquatic macroinvertebrates was developed for small sized rivers in the southern Apennines (south Italy). Eleven stream sites, impacted to a greater or a lesser extent by organic pollution and/or habitat impairment and chosen to cover the whole degradation gradient present in the geographical area were sampled in three seasons. The samples were collected following a proportional, multihabitat procedure, afterwards considering separately the replicates collected in the depositional (pool) and transport (riffle) areas for the analysis. A PCA multivariate analysis was performed to extract the main axes of variation of the biological community, which resulted in the first axis being strongly correlated to ecological quality. The final assessment module is based on a multimetric system, structured by selecting the best metrics in simulating the first axis gradient. The system considers a total of 15 different metrics, mainly providing information concerning tolerance to pollution, taxa richness, habitat features and trophic structure of the community. In accordance with the WFD requirements, some of these metrics are based on abundance classes of taxa. Depositional and transport units, due to the observed dissimilarity in the structure of their benthic communities, were kept separate during the development of the assessment system to retain this potentially useful information and to clear interpretation of the results. Both `riffle' and `pool' invertebrate data showed clear differences in ecological quality between sites. Nevertheless, the final assessment module is based on the macroinvertebrates inhabiting depositional areas of rivers only, because the metrics for these river units showed a better performance than those examined for the transport river units. The application of the assessment module requires 10 replicates to be quantitatively collected, for a total area of 0.5 m2. In terms of sampling and identification effort, the assessment module shows a good comparability with the standard Italian method presently in use and might thus be easily applied for river sites classification according to the Water Framework Directive in southern Italy. The site classification obtained with the proposed multimetric index shows a very good correspondence with the post-classification based on multivariate analysis. [ABSTRACT FROM AUTHOR]

Based on the requirements of the Water Framework Directive, a macroinvertebrate-based assessment system to evaluate the ecological quality of streams has been developed by AQEM project consortium. In the Czech Republic the impact of organic pollution was principal pressure studied, but some morphological degradation of some sampling sites could not be avoided. A multimetric assessment system for three stream types was developed. Detrended Correspondence Analysis was used for the detection of the response of macroinvertebrate communities to the gradient of organic degradation. Significant relationships between abiotic (BOD, TOC, nutrients) and biotic (saprobic index, ASPT) indicators of organic enrichment/eutrophication were identified. Separate storage of the riffle and pool components of each multi-habitat sample allowed differences between these habitats to be compared in context of the metrics applied in the assessment system. Lotic and lentic habitats differed in taxonomic composition, ecological traits and biotic indices. The separate assessment of the riffle and pool parts of samples provides additional useful information when combined effects of organic pollution and morphological degradation are to be considered. [ABSTRACT FROM AUTHOR]

The purpose of this study was to test the applicability of different methods of river habitat assessment and their respective indices in a series of sample sites in Italy. These investigations were carried out within the EU AQEM project with the aim of combining the macroinvertebrate information with that achieved by investigating the hydromorphological characteristics of the river ecosystem as well as the surrounding landscape features. The River Habitat Survey (including the derived indices Habitat Modification Score and Habitat Quality Assessment) from U.K., and three Italian indices (Index of Fluvial Functioning, Buffer Strip Index and Wild State Index) were applied at 33 AQEM sites distributed in three different Italian river types. The obtained results indicate the overall ability of the applied indices to detect the degradation gradient, including river morphology and habitat, in the studied riverine ecosystems. Index of Fluvial Functioning seems useful to promptly describe the ecological quality of rivers as suggested by the good correlation with the AQEM multimetric biotic index. The Buffer Strip Index, showing a clear affinity with the Habitat Quality Assessment, seems suitable to assess richness and quality of the physical structure of a riverine site. The Habitat Modification Score recorded efficiently the morphological impact where present (e.g., North Apennine river sites), while the Italian indices appear to be not appropriate for differentiating this impact type from the general degradation of rivers. [ABSTRACT FROM AUTHOR]

Longitudinal zonation concepts describe the downstream changes in chemico-physical and biological properties of rivers. Including information on ecological fish guilds can enhance the usefulness of fish zonation concepts, in a way that they can be used as tools for assessment and management of the ecological integrity of large rivers. We present an ecological characterization of fish zones and fish communities in near-natural and in regulated large rivers in Europe (the River Doubs in France and the Rivers Rhine and Meuse in the Netherlands), using guild classifications of several life-history traits of fish and national Red Lists of threatened species. The Doubs data set was also analyzed using indices of the sensitivity of fish species to environmental degradation and indices for eurytopy. In these rivers, the number of ecological guilds per zone increases downstream, and there are clear shifts in the structure of the guilds. Flow preference and reproduction ecology of river fish are closely linked. The proportion of rheophilic species in the fish community decreases downstream, and the proportions of limnophilic and eurytopic species increase. Lithophilic and psammophilic spawners are dominant in the upper zones, whereas the lower zones are dominated by phytophilic and phytolithophilic spawners. The proportion of zoobenthivorous and periphytivorous species decreases downstream, and the proportion of zooplanktivorous and phytivorous species increases. However, because the European fish fauna mainly consists of feeding generalists, the discriminative abilities of simplistic feeding guild classifications are not very high. Guilds of sensitive, stenoecious species that share life history strategies that are highly adapted to specific riverine conditions (rheophils and limnophils) have declined far more than generalist species that can survive in a wide range of habitats that are not characteristic of natural river ecosystems. Because of the subsequent over-abundance of the eurytopic species the original longitudinal fish zonations are hardly recognizable anymore in heavily impacted large rivers such as the River Rhine. Hence these rivers do not meet the criteria for ecological integrity. Within a specific fish region, a suitable way of analyzing and monitoring the impact of human disturbance on the structure of the fish community is by comparing the guild structure of the present state of a fish zone with that of the reference situation. [ABSTRACT FROM AUTHOR]

The effect of substrate heterogeneity on the structure of stream macroinvertebrate assemblages (total abundance, taxon richness, and evenness) is still not clear, but this could be due to the lack of standard methods for quantifying substrate heterogeneity. An accurate quantification of substrate heterogeneity was obtained from photographs of sampled areas (each 225 cm2), which were used to create maps that were subsequently digitized and analyzed using image analysis software. These maps allowed the calculation of multiple metrics quantifying two aspects of substrate heterogeneity: composition and spatial configuration of substrate patches. The diversity of substrate types (calculated as the Shannon diversity index), and the heterogeneity of patch compactness (calculated as the coefficient of variation of the relationship between patch dimensions) were the metrics explaining more biotic variance at the sample scale, but at higher scales there were no relationships between assemblage structure and substrate heterogeneity. Most variation in substrate heterogeneity occurred at the sample scale, while some metrics varied significantly at riffle or segment scales; these patterns of variation match those of macroinvertebrate assemblages, which had been previously studied. The importance of quantifying substrate heterogeneity and considering the spatial scales of its study are discussed. [ABSTRACT FROM AUTHOR]