M. T. Furse

The performance of a new biological water quality score system based on macroinvertebrates over a wide range of unpolluted running-water sites

Abstract The occurrence of families of macroinvertebrates has recently been used as the basis for the BMWP (Biological Monitoring Working Party) system of assigning scores to lotic sites. In this study the performance of the system across 268 sites on 41 rivers providing a wide range of physical and chemical features has been appraised. Changes in score and ASPT (average score per taxon) with respect to season and sampling effort have been examined. Seasonal variations were relatively slight and it is concluded that samples taken in any of the three seasons, spring, summer or autumn, were likely to provide consistent estimates of score and particularly ASPT. Sample replication led to substantial accretion of scores but had little effect on ASPT and therefore more information was obtained for less effort when ASPT was used. Data are presented on score and ASPT values for 8 groups of sites derived by multivariate classificatory techniques. Considerable variability in achievable score and ASPT was observed in the different groups of unpolluted sites. In general, scores were highest in the group at the middle of the range of environmental features and lowest in groups at the bottom of the range (lowland areas). ASPT in contrast showed a relatively steady decline in values between groups at the top (mainly upland rivers) and bottom of the range of environmental features. Attempts were made to predict score and ASPT from physical and chemical data, or physical data alone using multiple regression. Equations used to predict ASPT explained on average a higher proportion of the variance (65%) than those predicting scores (22%). It is suggested that predictive equations for ASPT will enable theoretical ASPT to be calculated, thus providing target values against which observed values can be compared. Recommendations to facilitate use and interpretation of the BMWP score system are presented.

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

Abstract 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.

The STAR project: context, objectives and approaches

STAR is a European Commission Framework V project (EVK1-CT-2001-00089). The project aim is to provide practical advice and solutions with regard to many of the issues associated with the Water Framework Directive. This paper provides a context for the STAR research programme through a review of the requirements of the directive and the Common Implementation Strategy responsible for guiding its implementation. The scientific and strategic objectives of STAR are set out in the form of a series of research questions and the reader is referred to the papers in this volume that address those objectives, which include: (a) Which methods or biological quality elements are best able to indicate certain stressors? (b) Which method can be used on which scale? (c) Which method is suited for early and late warnings? (d) How are different assessment methods affected by errors and uncertainty? (e) How can data from different assessment methods be intercalibrated? (f) How can the cost-effectiveness of field and laboratory protocols be optimised? (g) How can boundaries of the five classes of Ecological Status be best set? (h) What contribution can STAR make to the development of European standards? The methodological approaches adopted to meet these objectives are described. These include the selection of the 22 stream-types and 263 sites sampled in 11 countries, the sampling protocols used to sample and survey phytobenthos, macrophytes, macroinvertebrates, fish and hydromorphology, the quality control and uncertainty analyses that were applied, including training, replicate sampling and audit of performance, the development of bespoke software and the project outputs. This paper provides the detailed background information to be referred to in conjunction with most of the other papers in this volume. These papers are divided into seven sections: (1) typology, (2) organism groups, (3) macrophytes and diatoms, (4) hydromorphology, (5) tools for assessing European streams with macroinvertebrates, (6) intercalibration and comparison and (7) errors and uncertainty. The principal findings of the papers in each section and their relevance to the Water Framework Directive are synthesised in short summary papers at the beginning of each section. Additional outputs, including all sampling and laboratory protocols and project deliverables, together with a range of freely downloadable software are available from the project website at www.eu_star.at.

Detection of ecological change using multiple organism groups: metrics and uncertainty

A number of biological approaches are commonly used to assess the ecological integrity of stream ecosystems. Recently, it is becoming increasingly common to use multiple organism groups in bioassessment. Advocates of the multiple organism approach argue that the use of different organism groups should strengthen inference-based models and ultimately result in lower assessment error, while opponents argue that organism groups often respond similarly to stress implying a high degree of redundancy. Using fish, macroinvertebrate, macrophyte and benthic diatom data, site-specific parameters (e.g., water chemistry and substratum) and catchment variables from European mountain (n = 77) and lowland (n = 85) streams we evaluated the discriminatory power and uncertainty associated with the use of a number of biological metrics commonly used in stream assessment. The primary environmental gradient for both streams types was land use and nutrient enrichment. Secondary and tertiary gradients were related to habitat quality or alterations in hydromorphology. Benthic diatom and macroinvertebrate metrics showed high discriminatory power (R2 values often >0.50) and low error (<30%) with the primary (nutrient) gradient, while both fish and macrophyte metrics performed relatively poorly. Conversely, both fish and macrophyte metrics showed higher response (high coefficients of determination) than either benthic diatom or macroinvertebrate metrics to the second (e.g., alteration in habitat/hydromorphology) gradient. However, the discriminatory power and error associated with individual metrics varied markedly, indicating that caution should be exercised when selecting the ‘best’ organism group or metric to monitor stress.

The use of prediction to assess macroinvertebrate response to river regulation

A technique, which uses environmental data to predict the macroinvertebrate fauna of running water sites, was used to investigate the response of faunal communities to flow regulation below a set of upland reservoirs in Great Britain. Five variables (total oxidised nitrogen, alkalinity, chloride, substratum type and site distance from stream source) were used to predict family presence and abundance at 30 regulated sites. The predictions were compared with the observed fauna recorded in samples taking in spring, summer and autumn. Of the 37 commonly occurring families 22 showed statistically significant trends. Twelve of these occurred at lower abundances than predicted and the effect was greatest in Heptageniidae, Simuliidae, Elminthidae, Perlodidae and Rhyacophilidae. Ten families were more more abundant than predicted and these included Polycentropodidae, Sphaeriidae, Sialidae and some groups of chironomids and oligochaetes. Fifteen families showed no significant trends. Most families showed little difference in the observed and expected frequency of occurrence in the 30 sites but Taeniopterygidae and Perlidae amongst others occurred at less than the expected number of sites and Hydridae, Prodiamesinae and Muscidae occurred more commonly than expected. These faunal responses are discussed in relation to environmental changes arising from flow regulation. The possible uses of the predictive technique in simulating and assessing the effects of regulation on downstream fauna are outlined.

An appraisal of pond-net samples for biological monitoring of lotic macro-invertebrates☆

Abstract The use of a pond-net to sample benthic macro-invertebrates is assessed as a technique for use in a national classification scheme for running water sites. In a field trial, 6 pond-net samples of 3 min duration were taken at each of 4 sites on the River Axe in south-west England. Three different people each took 2 samples at each of the sites. A comparison of the number of families and species caught indicated significant differences with respect to sites, operators and site x operator interactions. Significant inter-operator differences in the number of taxa removed from samples were also shown at the sample processing stage, but only at family level. Despite these differences, clustering and ordination procedures showed strong site faithfulness for each series of 6 samples when data were analysed at species level. Similar analyses at family level produced several misclassifications of samples with those from other sites. Most of these misclassifications were eliminated when categories of abundance were applied to the family level data. A 3 min sample collected approx. 62% of families and 50% of species that could be attained at a site by 18 min netting. The results of this field trial provided justification for the use of a pond-net as the principal sampling technique in the classification exercise.

The ecological status of European rivers: evaluation and intercalibration of assessment methods

In this special issue we present the major results of the EU funded research project STAR (Standardisation of River Classifications: Framework method for calibrating different biological survey results against ecological quality classifications to be developed for the Water Framework Directive; contract number EVK1-CT-2001-00089).

Indicators of ecological change: comparison of the early response of four organism groups to stress gradients

A central goal in monitoring and assessment programs is to detect change early before costly or irreversible damage occurs. To design robust early-warning monitoring programs requires knowledge of indicator response to stress as well as the uncertainty associated with the indicator(s) selected. Using a dataset consisting of four organism groups (fish, macrophytes, benthic diatoms and macroinvertebrates) and catchment, riparian and in-stream physico-chemical variables from 77 mountain and 85 lowland streams we determined the relationships between indicator response and complex environmental gradients. The upper (>75th percentile) and lower (<25th percentiles) tails of principal component (PC) gradients were used to study the early response of the four organism groups to stress. An organism/metric was considered as an early warning indicator if the response to the short gradients was more robust (higher R2 values, steeper slope and lower error) than the null model (organism response to the full PC gradient). For mountain streams, both fish and macrophyte CA scores were shown to exhibit an early warning response to the upper tail of the 1st PC gradient when compared to the null model. Five of the eight metrics showed better response to the upper tail of the 2nd PC gradient compared to the null model, while only one metric (macrophyte CA scores) showed improvement when compared to the lower tail of the 2nd PC gradient. For lowland streams all four organism-groups showed better response (CA scores) to the upper tail of the PC gradient when compared to the null model. Only one metric (fish CA scores) regressed against the lower tail of the 2nd PC gradient was found to be more robust than the PC2 null model. These findings indicate that the nonlinear relationships of organism/metric response to stress can be used to select potentially robust early warning indicators for monitoring and assessment.

Intercalibration and comparison — major results and conclusions from the STAR project

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.

The validation of common European class boundaries for river benthic macroinvertebrates to facilitate the intercalibration process of the Water Framework Directive

The Water Framework Directive (WFD) requires that all the water bodies in Europe be protected and enhanced to achieve Good Ecological Status by 2015. The intercalibration of the biological monitoring results of Member States has to be carried out in relation to classification tasks to guarantee a common understanding of ‘Good Ecological Status’ at a European level. An intercalibration exercise was carried out within the framework of different Geographical Intercalibration Groups (GIGs), each composed of a group of countries that share similar river types and have a discrete geographical range. By means of the intercalibration exercise, common European boundaries were proposed for river invertebrate assessment methods within each GIG. The purpose of this study was to validate the boundaries proposed for the formal intercalibration exercise. A benchmark data set was used, which comprised data, collected in different European countries that satisfied WFD requirements. The data set included a set of reference sites and provided evidence of a high degree of comparability among countries. The STAR Intercalibration Common Metric index (STAR_ICMi) was calculated for benchmark samples and was selected as the index in which national assessment boundaries were expressed. It was applied for the intercalibration exercise in two GIGs. For the STAR_ICMi, the coefficient of variation was also calculated, demonstrating a comparable variability with indices that are based on species level identification. A fixed percentile of reference samples STAR_ICMi values was selected as the boundary between High and Good status. The range from this fixed percentile to the lowest possible value was divided into four equal parts to obtain the remaining class boundaries. The resulting High/Good and Good/Moderate boundaries were compared to the boundaries proposed by GIGs and proved to be in line with those defined in the intercalibration exercise. Even if, for the intercalibration exercise, some procedures to check the Member States (MS) data sets where put into practice, it is the responsibility of each state to guarantee the WFD compliancy of their reference conditions and methods. Accordingly, the process of validation explained in this article, or similar ones, can be an important step forward and demonstrate the comparability of the actual boundaries.