Ecological Quality Of Rivers Research Articles

A next-generation sequencing approach to river biomonitoring using benthic diatoms

AbstractDiatoms are main bioindicators used to assess the ecological quality of rivers, but their identification is difficult and time-consuming. Next Generation Sequencing (NGS) can be used to study communities of microorganisms, so we carried out a test of the reliability of 454 pyrosequencing for estimating diatom inventories in environmental samples. We used small subunit ribosomal deoxyribonucleic acid (SSU rDNA), ribulose-1, 5-bisphosphate carboxylase (rbcL), and cytochrome oxidase I (COI) markers and examined reference libraries to define thresholds between the intra- and interspecific and intra- and intergeneric genetic distances. Based on tests of 1 mock community, we used a threshold of 99% identity for SSU rDNA and rbcL sequences to study freshwater diatoms at the species level. We applied 454 pyrosequencing to 4 contrasting environmental samples (with one in duplicate), assigned taxon names to environmental sequences, and compared the qualitative and quantitative molecular inventories to those...

Response of fish and benthic invertebrate communities to constrained channel conditions in a mountain river: Case study of the Biała, Polish Carpathians

Abstract Following considerable hydromorphological degradation in past decades, the gravel-bed Biala River, Polish Carpathians, is to be restored through establishing erodible corridor in two river sections. In these sections, relatively long, unmanaged channel reaches alternate with short, channelized reaches located in the vicinity of bridges. Effects of the alternating morphologies on physical habitat conditions, fish and benthic invertebrate communities, and ecological river quality were investigated in 10 pairs of unmanaged and channelized cross-sections located between significant tributaries. Unmanaged cross-sections with an average of two low-flow channels exhibited significantly greater variation in depth-averaged and near-bed velocity and bed material size than single-thread, channelized cross-sections. Summer, autumn and winter surveys of benthic invertebrates indicated that the unmanaged cross-sections typically hosted three times more taxa than channelized cross-sections, and this was reflected in distinct appraisal of the two cross-section types by means of invertebrate-based BMWP-PL index. Electrofishing indicated no statistically significant difference in the number of fish species between both types of river cross-sections, and the resultant similar scores of the European Fish Index allowed both cross-section types to be associated with the same class of ecological river quality. This study indicated that short channelized river reaches do not disrupt continuity of fish populations, although they provide worse habitats for fish, reflected in the lower numbers of individuals, especially juveniles. It also highlighted the need of investigating various groups of river biota to determine the response of river biocoenosis to environmental stressors and evaluate the ecological status of the river.

Plant invasions in the rivers of the Iberian Peninsula, south-western Europe: A review

Aquatic and riparian ecosystems are known to be highly vulnerable to invasive alien species (IAS), especially when subjected to human-induced disturbances. In the last three decades, we have witnessed a growing increase in plant invasions in Portugal and Spain (Iberian Peninsula, south-western Europe), with very detrimental economic, social and ecological effects. Some of these species, such as the giant reed (Arundo donax L.) and the water hyacinth (Eichhornia crassipes (Mart.) Solms-Laub.), number among the world's worst weeds. We present an appraisal of this invasive alien river flora and the most problematic aquatic weeds. We review various aspects of invasion ecology, including spatial and temporal patterns of invasion, species invasiveness, species traits of invasive weeds, and relationships between human disturbance in rivers and surrounding areas and invasibility, and contextualize them in overall state-of-the-art terms. We also acknowledge the use of IAS as bioindicators of the ecological quality of rivers, wetlands and riparian zones. Remote-sensing tools and Geographic Information Systems for detecting and monitoring IAS in Iberian rivers are presented.

The use of benthic macroinvertebrate families for river quality assessment in Lithuania

AbstractThe aim of this study was to evaluate the influence of environmental factors on the distribution of macroinvertebrate taxa in different sized lowland Lithuanian rivers. A secondary aim was to assess ecological river quality and to determine the most suitable biotic index. A final aim was to determine the most appropriate macroinvertebrate families for river quality assessment in Lithuania. Species composition and quantitative characteristics of benthic macroinvertebrate communities have been investigated using standard kick-sampling method by a standard hand net in 24 different river sites in spring. Physical and chemical environmental parameters were measured in the same study site as the macroinvertebrate sampling. A total of 186 taxa representing 66 families or higher taxonomic ranks of benthic macroinvertebrates have been identified. Water temperature and current velocity influenced the highest number of ivestigated families. Seven of the most tolerant and eleven of the most sensitive macroinvertebrate taxa for hydrochemical parameters related with organic pollution were determined. The DSFI method was founded to be the best index for assessment of ecological status for Lithuanian rivers until more accurate estimation method will be created.

Assessing Ecological Water Quality with Macroinvertebrates and Fish: A Case Study from a Small Mediterranean River

Biological elements, such as benthic macroinvertebrates and fish, have been used in assessing the ecological quality of rivers according to the requirements of the Water Framework Directive. However, the concurrent use of multiple organism groups provides a broader perspective for such evaluations, since each biological element may respond differently to certain environmental variables. In the present study, we assessed the ecological quality of a Greek river (RM4 type), during autumn 2003 and spring 2004 at 10 sites, with benthic macroinvertebrates and fish. Hydromorphological and physicochemical parameters, habitat structure, and riparian vegetation were also considered. Pollution sensitive macroinvertebrate taxa were more abundant at headwaters, which had good/excellent water quality according to the Hellenic Evaluation System (HES). The main river reaches possessed moderate water quality, while downstream sites were mainly characterised as having bad or poor water quality, dominated by pollution-tolerant macroinvertebrate taxa. Macroinvertebrates related strongly to local stressors as chemical degradation (ordination analysis CCA) and riparian quality impairment (bivariate analysis) while fish did not. Fish were absent from the severely impacted lower river reaches. Furthermore, external pathological signs were observed in fish caught at certain sites. A combined use of both macroinvertebrates and fish in biomonitoring programs is proposed for providing a safer assessment of local and regional habitat impairment.

“HKH screening”: a field bio-assessment to evaluate the ecological status of streams in the Hindu Kush-Himalayan region

A macro-invertebrate-based field screening method for assessing the ecological status of rivers in the Hindu Kush-Himalayan Region is presented herein. The method was developed within an EU-funded project called “Development of an Assessment System to Evaluate the Ecological Status of Rivers in the Hindu Kush-Himalayan Region (ASSESS-HKH)”. The data originate from five countries: Bangladesh, Bhutan, India, Nepal, and Pakistan. The main instrumental method used was a screening protocol based on the Austrian method for screening the ecological quality of rivers and streams. The conception of the method, its adoption to the conditions in the Hindu Kush-Himalayan Region, and the application of the protocol are described comprehensively. The assessment procedure was based on sensory criteria and biota that can be identified in the field, with a special focus on benthic macro-invertebrates. The basic principles of benthic bio-indicators’ assortment are described. The determination of individual bio-indicative values is demonstrated for selected examples. An NMS analysis was performed to describe the intra- and inter-similarities of benthic invertebrate assemblages in streams of different eco-regions. As a result, two different HKH screening protocols are provided: one for rivers in mountainous regions and one for lowland rivers. The performance of the screening method in the region and its validation as a rapid, cost-effective, and scientifically based tool for river quality assessment is discussed.

Development of the HKHbios: a new biotic score to assess the river quality in the Hindu Kush-Himalaya

Within the ASSESS-HKH project (Development of an Assessment System to Evaluate the Ecological Status of Rivers in the Hindu Kush-Himalayan (HKH) region—a research project funded by the European Union; contract number: INCO-CT-2005-003659) a benthic invertebrate-based scoring system (HKHbios; Hindu Kush-Himalayan biotic score) was developed. The development was based on multi-habitat samples from 198 sampling sites located in five ecoregions and five Asian countries (Bangladesh, Bhutan, India, Nepal and Pakistan) taken in two different seasons (pre- and post-monsoon). Environmental and biological screening data were used to select macro-invertebrates as indicators for the ecological river quality. Taxa scores were assigned based on the range and distribution patterns of taxa amongst different degrees of impact and on available autecological information. In total, 199 taxa were scored for the HKHbios, which is calculated a weighted average score per taxon (ASPT). The range of the index values under different degrees of stress was evaluated and a five-class quality assessment system was generated for each ecoregion. Correlation analysis between the HKHbios, 38 selected environmental parameters and complex PCA gradients were used to test the response of the HKHbios to different kinds of impact.

Exploring the interactions between flood defence maintenance works and river habitats: the use of River Habitat Survey data

Abstract More extensive physical management of rivers in response to increasing flood risk, and action to improve the ecological quality of rivers represent two major, and potentially conflicting, challenges. Improved understanding of the interactions between flood defence works and habitat structure must be achieved in order to satisfy both of these demands in the context of flood risk management and habitat improvement. This paper examines the ‘extensive’ and ‘intensive’ use of data derived from a standardized method of assessing habitat character to explore the effects of flood risk maintenance works on river habitat quality. Analysis of the UK River Habitat Survey (RHS) data set reveals some broad trends towards reduced habitat heterogeneity associated with recent flood defence works such as dredging and weed‐cutting. These observations correspond with published localized experimental work and suggest that the RHS database can be a useful resource for identifying relationships at relatively broad scales. Applying the RHS methodology at finer spatial scales for sites experiencing continuing maintenance reveals contrasting results and highlights some key methodological issues; these include the availability and selection of high quality benchmark conditions, the legacy of past management, lag times associated with maintenance and recovery, and recording of marginal habitat features. Small modifications to the RHS method could enable calculation of more detailed habitat indices while maintaining comparability with the national dataset. If the issues identified in this paper can be addressed or accounted for, RHS could be an important tool for assessing the relationship between flood defence management and new statutory obligations for ecological improvement. Copyright © 2009 John Wiley & Sons, Ltd.

Does the lentic-lotic character of rivers affect invertebrate metrics used in the assessment of ecological quality?

The importance of local hydraulic conditions on the structuring of freshwater biotic communities is widely recognized by the scientific community. In spite of this, most current methods based upon invertebrates do not take this factor into account in their assessment of ecological quality. The aim of this paper is to investigate the influence of local hydraulic conditions on invertebrate community metrics and to estimate their potential weight in the evaluation of river water quality. The dataset used consisted of 130 stream sites located in four broad European geographical contexts: Alps, Central mountains, Mediterranean mountains and Lowland streams. Using River Habitat Survey data, the river hydromorphology was evaluated by means of the Lentic-lotic River Descriptor and the Habitat Modification Score. To quantify the level of water pollution, a synoptic Organic Pollution Descriptor was calculated. For their established, wide applicability, STAR Intercalibration Common Metrics and index were selected as biological quality indices. Significant relationships between selected environmental variables and biological metrics devoted to the evaluation of ecological quality were obtained by means of Partial Least Squares regression analysis. The lentic-lotic character was the most significant factor affecting invertebrate communities in the Mediterranean mountains, even if it is a relevant factor for most quality metrics also in the Alpine and Central mountain rivers. Therefore, this character should be taken into account when assessing ecological quality of rivers because it can greatly affect the assignment of ecological status.

River restoration in the UK: Meeting the dual needs of the European union water framework directive and flood defence?

A major component of river restoration is the recreation of instream physical habitat heterogeneity and re‐establishment of the linkage between the in‐channel and adjacent floodplain environment. Re‐engineering channels to reinstate a more natural form and the restoration of water and sediment transfer can bring multiple benefits particularly if undertaken as part of an environmental strategy for the whole catchment. The benefits usually include improvements to the ecological quality of rivers and reductions in the severity of flooding downstream. These benefits are achievable because rivers in their natural state are ecosystems that maintain high bio‐diversity, floodplains when inundated attenuate flows, and flooding of low‐lying areas creates wetlands and washlands of high nature conservation value and flood storage potential. This paper will explore (i) how the European Union Water Framework Directive (WFD) (EC, 2000) will become an increasingly important driver for catchment‐based river restoration in the UK, and (ii) how river restoration has the potential to deliver ecological improvements in rivers consistent with WFD targets whilst, at the same time, providing more sustainable flood management.

Assessment of sources of uncertainty in macrophyte surveys and the consequences for river classification

The application of macrophytes in freshwater monitoring is still relatively limited and studies on their intercalibration and sources of variation are required. Therefore, the aim of the study was to compare selected indices and metrics based on macrophytes and to quantify their variability. During the STAR project, several aspects influencing uncertainty in estimation of the ecological quality of river were assessed. Results showed that several metrics based on the indicative value of plant species can be used in evaluation of the ecological status of rivers. Among estimated sources of variance in metric values the inter-surveyor differences had the lowest effect and slightly stronger were the influences of temporal variation (years and seasons) and shading. The impact of habitat modification was the most important factor. Analysis showed that some of macrophyte-based metrics (notably MTR and IBMR) are of sufficient precision in terms of sampling uncertainty, that they could be useful for estimating the ecological status of rivers in accordance with the aims of the Water Framework Directive.

Links Between Anthropogenic Perturbations and Benthic Macroinvertebrate Assemblages in Afromontane Forest Streams in Uganda

Relationships between environmental variables and benthic macroinvertebrate assemblages were investigated among several sites that varied in disturbance history in Bwindi Impenetrable National Park, an Afromontane site in East Africa. Environmental variables were correlated with the level of past catchment disturbance – logging, agricultural encroachment, and present tourism activity. For example, sites in medium and high disturbance categories had higher values of specific conductance and lower water transparency than low disturbance category sites, these environmental variables may therefore act indicators of ecological quality of rivers. Environmental variables such as conductivity and water transparency were found to be good predictors of benthic macroinvertebrate assemblages, with anthropogenically stressed sites having lower diversity than the reference sites. Impacted sites were dominated by tolerant taxa such as chironomid and leeches, while ‘clean water’ taxa such as Ephemeroptera, Plecoptera and Trichoptera dominated at minimally impacted sites. Comparison of sites with different disturbance histories provided evidence for differences in benthic macroinvertebrate communities that reflect the state of forest restoration and recovery. We recommend quarterly monitoring of water quality to act as an early warning system of deterioration and tracking ecological recovery of previously impacted sites.

Towards sustainable flood risk management in the Rhine and Meuse river basins: synopsis of the findings of IRMA‐SPONGE

Recent flood events in western Europe have shown the need for improved flood risk management along the Rhine and Meuse rivers. In response, the IRMA-SPONGE research programme was established, consisting of 13 research projects, in which over 30 organizations from six countries co-operated. The aim of IRMA-SPONGE was the development of methods and tools to assess the impact of flood risk reduction measures and of land-use and climate change scenarios, in order to support the spatial planning process for the Rhine and Meuse River Basins. Several important conclusions were agreed upon by participants in the programme; they emphasize the role of spatial planning, especially in areas at risk of flooding, as an important component of flood risk management: 1 Flood risk, defined as a function of both flood probability and potential damage, is increasing not only due to climate change (likely to cause an increase in the probability of extreme discharges) but also due to continued investment in areas at risk of flooding (resulting in an increase in potential damage). 2 Water retention areas and land-use adaptations far upstream may be useful in lowering the frequency of floods in small basins. However, extreme floods far downstream in the lower Rhine and Meuse basins, where the probability of design discharges is less than 1/200 per year, cannot be prevented by such upstream measures. 3 The most effective and sustainable reduction of flood risks could be achieved by reducing the potential damage (vulnerability) in flood-prone areas through adapted land use and spatial planning. 4 Flood risk management organizations should not only aim at a reduction of flood risk but should also seek to enhance the ecological quality of rivers and floodplains.

RIVPACS models for predicting the expected macroinvertebrate fauna and assessing the ecological quality of rivers

The European Union Water Framework Directive recognises the need for and value of biological monitoring. This paper reviews the modelling approach known as River Invertebrate Prediction and Classification System (RIVPACS ) for assessing the ecological quality of river sites using macroinvertebrate sampling. The RIVPACS philosophy is to develop statistical relationships between the fauna and the environmental characteristics of a large set of high quality reference sites which can be used to predict the macroinvertebrate fauna to be expected at any site in the absence of pollution or other environmental stress. The observed fauna at new test sites can then be compared with their site-specific expected fauna to derive indices of ecological quality. All methodological decisions in any such model development have implications for the reliability, precision and robustness of any resulting indices for assessing the ecological quality and ecological grade (‘status’) of individual river stretches. The choice of reference sites and environmental predictor variables, the site classification and discrimination methods, the estimation of the expected fauna, and indices for comparing the agreement, or lack of it, between the observed and expected fauna, are all discussed. The indices are assessed on the reference sites and on a separate test set of 340 sites, which are subject to a wide range of types and degrees of impairment.

Sampling variation in macroinvertebrate data and implications for river quality indices

SUMMARY 1. The EC Water Framework Directive (2000/60/EC) recognises the need for biological monitoring. Indices derived from standard samples of macroinvertebrates are frequently used for the appraisal of the ecological quality of rivers. However, information on the errors or chance variation that can influence the value of an index is also important.2. This paper describes a study to quantify the observed sampling variation in three ecological indices based on the Biological Monitoring Working Party (BMWP) score system across a wide range of river types and qualities. The indices are number of BMWP taxa, BMWP score and Average Score Per Taxon (ASPT).3. The study sites were selected to encompass the four major groups within the River InVertebrate Prediction And Classification System (RIVPACS) site classification for Britain. Within each group, four sites which differed in ecological quality grade were chosen (total of 16 sites). At each site three standard RIVPACS samples were taken in each of spring, summer and autumn by trained staff. In each season, two samples were taken by one biologist and the third by a different individual to allow for within and between‐operator variation.4. The effects of sampling variation within a season on the number of taxa, BMWP score and ASPT across all sites, irrespective of operator, could be represented by some simple parameters. We found that the sampling SD of the square root of the number of taxa, square root of BMWP score and the untransformed ASPT were roughly constant in each case, irrespective of site type or quality. For each index, SD for two and three seasons combined samples were smaller than for single season samples.5. Inter‐operator influences on sample values were negligible (4–12% of total sampling SD) in this study. This underlines the importance of adequate training for all staff involved in extensive monitoring programmes which use standard procedures from one year to the next, but may involve different staff.6. Indices for number of taxa, BMWP score and ASPT were all estimated with greater precision from combined season samples than from the averages of two or three seasons' samples.7. This study enables us to estimate confidence intervals for the values of the number of taxa, BMWP score and ASPT based on single season, two or three season combined samples collected using standard RIVPACS procedures for any river site in Britain. The results can also be used in simulation models which incorporate the effects of sampling variation into assessments of the ecological quality of river sites based on the ratio of observed to RIVPACS expected values of these BMWP indices.

Hydrology and the ecological quality of Scottish river ecosystems

Hydrology is a primary control on the ecological quality of river systems, through its influence on flow, channel geomorphology, water quality and habitat availability. Scottish rivers are widely perceived to be of high ecological quality, with abundant flow volumes and high water quality. However, historical and current river flow regulations, and land use change have altered the physical and chemical characteristics of Scottish rivers, with adverse consequences for aquatic biota. Baseline hydrological, geomorphological and water quality conditions in Scottish rivers are thus summarised. The impacts of river regulation and land use change on the hydrology, geomorphology and water quality of Scottish rivers are then discussed. Consequences of these changes for aquatic habitat are examined, with particular reference to the economically significant salmonid species ( Salmo salar and Salmo trutta). Policy and management issues relating to the future ecological quality of Scottish rivers are reviewed. These include the impacts of climate change on ecological quality, the calculation and implementation of ecologically acceptable flows, and river restoration and best management practices within integrated catchment planning.

A Europe-wide system for assessing the quality of rivers using macroinvertebrates: the AQEM Project*) and its importance for southern Europe (with special emphasis on Italy)

The AQEM Project aims to develop a Europe-wide system for monitoring the ecological quality of rivers using macroinvertebrates, to satisfy the requirements of the EU Water Framework Directive. Three main types of anthropogenic perturbation are being investigated: morphological degradation, water (organic) pollution and acidification (the last is not under investigation in Italy). The selection of reference and impaired study sites is discussed. Particular attention is paid to the problems encountered when defining reference conditions. The initial stages of the project highlighted the lack of a Europe-wide definition of river types. The future development of such a typology from the AQEM database is discussed. The standard AQEM data gathering methods are presented, from background information about sites to the microhabitat-based macroinvertebrate sampling method. The extended fieldwork methods used in Italy are described. These included the separate analysis of the invertebrate assemblages from each replicate, the recording of additional microhabitat variables for each replicate and the completion of large-scale survey techniques for each site (including RHS). The extended method was designed to enhance the important ecological information available from the dataset, particularly relevant in Italy where significant gaps exist in the taxonomic and ecological knowledge of many macroinvertebrate taxa. Preliminary and expected findings are presented, including examples of the range and habitat selection of two species of Ephemeroptera endemic to Italy, as well as data relating to the number of taxa found at a site with increasing numbers of microhabitat replicates taken. The importance of the AQEM Project not only for biomonitoring, but also for ecology, taxonomy and conservation, in Italy and for the south of Europe in general, is emphasised.