Ecological Quality Classes Research Articles

Comparison of bioassessment results and costs between preserved and unpreserved macroinvertebrate samples from streams

The choice to use or not use a preservative before sorting macroinvertebrate samples (i.e., dead specimens vs. living specimens) is based on studies not solely focused on the effects of preservation. Using identical sample processing protocols, we compared preserved and unpreserved samples for the following parameters: (1) the number of taxa and individuals for each major macroinvertebrate group, (2) ecological quality classes calculated with a multimetric index developed for the assessment of small Dutch lowland streams, and (3) costs of sample processing. We collected macroinvertebrate samples from three lowland streams in the Netherlands. At each site, we collected six replicate samples, of which three samples were preserved and three were not. Significantly different numbers of Ephemeroptera individuals and Hydracarina taxa and individuals were collected from preserved samples compared to unpreserved samples. In assessments based on these individual metrics, standardization of sample processing will be required. In streams with Ephemeroptera, the preservation of samples is necessary to optimize the number of Ephemeroptera individuals collected. In streams that contain Hydracarina, the preservation of samples will result in an underestimation of the number of Hydracarina taxa and individuals present. In only one instance there was a difference in ecological quality between preserved and unpreserved samples, indicating that assessing small Dutch lowland streams does not require standardization of sample preservation as part of the sample processing protocol. We detected no significant differences in sample processing costs between preserved and unpreserved samples.

Integrating the fish embryo toxicity test as triad element for sediment toxicity assessment based on the Water Framework Directive approach

Purpose The objective of this study was to complement analyses according to the European Union Water Framework Directive (WFD) with a sediment toxicity analysis as part of an integrated river assessment. To this end, Hessian water courses were analyzed using the sediment quality triad concept according to Chapman with chemical analyses, in situ effect evaluations, and ecotoxicological assessments. For the ecotoxicological assessment (fish embryo toxicity test with Danio rerio), a new evaluation scheme was developed, the fish teratogenicity index (FTI), that allows for a classification of sediments into ecological quality classes compliant to the WFD.

An insight into the performance of benthic classification indices tested in Eastern Mediterranean coastal waters

This work evaluates four indices that have been used for benthic macroinvertebrate ecological quality classification in the Mediterranean Sea. Our study was based on the data obtained from the participation of Greece and Cyprus in the Mediterranean Geographical Intercalibration group. The indices AMBI, M-AMBI, MEDOCC and BENTIX were applied to the available benthic species data, and the succession of the ecological groups along the graded values of each index was plotted. The level of agreement among methods was calculated, and the performance of each method in estimating ecological quality status was evaluated. AMBI, based on the Atlantic model, and its derivative M-AMBI overestimated the statuses, while MEDOCC showed the best level of agreement with BENTIX. BENTIX gives equal weight to tolerant and opportunistic species groups, which correlates them more closely than the other indices and makes BENTIX the most sensitive in detecting ecological disturbances in the Eastern Mediterranean basin, where tolerant and opportunistic groups seem to play an equally important role in the response of benthic communities to stressors.

Ecological quality classes of river hydromorphology in Poland

This work presents rules and results of classifications of hydromorphological status of watercourses used presently in Europe. The Water Framework Directive introduced an obligation to monitor hydromorphological elements of rivers, which include hydrological regime, river continuity and bed morphology. European standards require somewhat different quality indicators and the way of their assessment for such investigations. Classification of status and ecological potential shall include categories and types of rivers, however, the methods existing so far do not provide such a distinction. Assessment of much differentiated features and attributes, as well as the requirement of presenting the outcome in EQR form, within limits from zero to one, cause that all the studied parameters, which are very diverse, must be conveyed to numerical form. The MHR method takes into account the above conditions and proposes a classification which includes limit values for five classes of status and four classes of ecological potential. It assumes limit values of classes lowering from natural watercourses through heavily modified to artificial.

Assessment of running waters (Slovakia) using benthic macroinvertebrates — derivation of ecological quality classes with respect to altitudinal gradients

AbstractA method is presented for defining the five classes of ecological quality based on a multimetric index (MMI) of macroinvertebrates, as required for implementation of the Water Framework Directive for small (catchment area 10–100 km2), medium (101–1000 km2) and large (> 1000 km2) streams. Our method (expert judgment) allows us to overcome an absence of reference sites for some stream types. The key was selection of suitable metrics for all stream types. The whole procedure was divided into two parts. 1. Small streams with reference sites: suitable metrics were selected according to their ability to distinguish reference and monitoring sites — SI, Oligo [%], BMWP, RhiTI, Rheoindex, IBCR, % Aka+Lit+Psa [%] and EPT. Here the high-good boundary value was set as the 25th (for metrics decreasing with increasing pollution) or 75th percentile (for metrics increasing with increasing pollution). 2. Medium and large streams which lack reference sites: here the idea was applied that some metrics, the values of which change along an altitudinal gradient, also react to anthropogenic stress — SI, Oligo [%], BMWP, [%] metarhithral, RhiTI, Aka+Lit+Psa [%] and EPT for both medium and large streams with, in addition, IBCR and NFam for medium streams. This assumption was supported by regression analysis of altitude and metrics from small streams. Not all the metrics were related to altitude but metrics with a good ability to separate reference and monitoring sites did show a significant relationship to altitude. The boundary between high and good class for medium and large streams was set as the 95th or 5th percentiles.

Assessment of the ecological status of European surface waters: a work in progress

The ‘normative definitions’ of ecological water quality classes given by the Water Framework Directive (WFD) are narrative descriptions of the conditions present in water bodies of different qualities relative to reference conditions found in unimpacted sites. In order to fill these descriptions with a more solid content, the definitions have been a subject of intensive development of quantitative methodologies for ecological status assessment as well as for rules and criteria for setting of reference conditions and ecological status boundaries for classification of water bodies. In this article, we recall the basic principles of the WFD that sometimes have been overlooked and point out some gaps remained and problems arisen during the ongoing implementation of the directive. Defining type-specific reference conditions for water bodies and finding biological metrics that sensitively reflect only the anthropogenic deviations from those conditions are the biggest challenges that the ecological status assessment faces. So far, there is no guarantee that reference conditions are comparable across EU Member States due to a lack of common criteria, which need still to be elaborated. Defining site-specific reference conditions instead of type specific is a novel approach that allows for minimizing uncertainties introduced by applying broad types. Search for new metrics has led to a real boom of multimetric indices which ought to be the adequate tool to measure the multiple human impairments but which should pass a thorough check before being included in monitoring programs. Curiously, some biological indices constructed as surrogates for chemistry (especially nutrients) start ‘living their own life’ and continue indicating the disturbance when the controlling factors change. This shows the obvious advantage of biological indicators against chemical ones. New challenges to WFD implementation are brought about by the need to consider the effects of alien species and climate change in the assessment framework, and by the nonlinear dose—response relationships dominating in biological systems. Attempts to diminish uncertainties in quality assessment have become a new labour-intensive field for researchers.

Within-stream variability of benthic invertebrate samples and EU Water Framework Directive assessment results

The EU Water Framework Directive (WFD) demands for an integrated biological assessment of surface water bodies. The assessment should use “Biological Quality Elements” as indicators and be based on comparing the observed biota with stream type specifi c reference condition biota to refl ect the impact of various stressors. Moreover, the WFD demands that restoration measures must be taken whenever the Ecological Quality Class (EQC) is “Moderate” or worse. Therefore, it is important to know the reliability of assessment results in order to judge whether an expensive restoration measure is justifi ed or not. The degree of uncertainty is linked with the variability of the data. The aim of the present study was to investigate the variability of benthic invertebrate samples of running waters. In 26 mid-sized streams in Germany, two samples were taken following a slightly modifi ed STAR/AQEM protocol (NTotal = 52). The STAR/AQEM protocol (Furse et al. 2006, STAR consortium 2003) is the result of two successive EU-funded projects, which aimed to develop a standardised macroinvertebrate sampling protocol and assessment system for running waters (Furse et al. 2006, Hering et al. 2003). STAR/AQEM multi-habitat sampling is based on 20 sampling units, which are distributed proportional to the estimated microhabitat covers at a sampling site. The two samples of each stream were taken at sites which were relatively close to one another (100 to 650 m) and had similar structural parameters, hydromorphology and physical/chemical parameters. Thus, it was expected that biocoenoses at both sites and assessment results should be similar. However, the results showed that samples differed in terms of number of taxa and abundances. These differences caused deviations in metric results, including the Multimetric Index (MMI) and its constituent core metrics, such as the percentage of EPT-Taxa (EPT [%]) or number of EPTCBO-Taxa (EPTCBO). In 10 of 26 cases the differences in metric assessment results led to different ecological quality classes (EQCs). In order to quantify uncertainty in assessment results, the STARBUGS simulation software was used. By simulating metric scores based on the observed sampling variance in the present data set, this software calculates the confi dence probability of a sample belonging to each of the fi ve possible EQCs. For the MMI the average confi - dence probability that a stream site truly belonged to the EQC estimated from the observed sample was 89 %. This means that the probability that a stream site belongs to a different EQC than the assessment result indicates was quite low (approximately 11 %). However, it is discussed that the given confi dence probabilities can only be used to estimate the precision of the analysed samples – the results cannot be used for estimating the probability of future samples delivering the same assessment result. Moreover, the present study revealed that certain metrics are more susceptible to variability (EPT [%], EPTCBO) than others (e.g. German Fauna Index “GFI”). The reasons for variability and consequently uncertainty inherent to benthic invertebrate samples are discussed. The results of the present study stress the importance of implementing standardised sampling and sorting protocols and quality control mechanisms in benthic invertebrate assessment schemes.

Chlorophyll reference conditions for European lake types used for intercalibration of ecological status

The Water Framework Directive (WFD), requires European Member States to assess the “ecological status” of surface waters. As part of this, many European countries have developed an ecological quality classification scheme for chlorophyll concentrations as a measure of phytoplankton abundance. The assessment of ecological quality must be based on the degree of divergence of a water body from an appropriate baseline, or ‘reference condition’. It is, therefore, necessary to determine chlorophyll reference conditions for all European lake types. This involves examining how chlorophyll concentrations vary by lake type, in the absence of any nutrient pressures from agriculture or wastewater. For this purpose, a dataset of 540 European lakes considered to be in a relatively undisturbed reference condition has been assembled, including data on chlorophyll concentration, altitude, mean depth, alkalinity, humic content, surface area and geographical region. Chlorophyll was found to vary with lake type and geographical region, and to be naturally highest in low-altitude, very shallow, high alkalinity and humic lake types and naturally lowest in clear, deep, low alkalinity lakes. The results suggest that light and mineral availability are important drivers of chlorophyll concentrations in undisturbed lakes. Descriptive statistics (median and percentiles) of chlorophyll concentrations were calculated from populations of lakes in this reference lake dataset and used to derive lake-type specific reference chlorophyll concentrations. These reference conditions can be applied, through a comparison with observed chlorophyll concentrations at a site, in the assessments of ecological status and provide a consistent baseline to adopt for European countries.

Defining chemical status of a temporary Mediterranean River

Although the majority of rivers and streams in the Mediterranean area are temporary, no particular attention is being paid for such systems in the Water Framework Directive (WFD). A typical temporal Mediterranean river, draining an intensively cultivated basin, was assessed for its chemical status. Elevated concentrations of nitrates and salts in river water as well as nutrients and heavy metals in river sediments have been attributed to agricultural land uses and practices and point sources of organic pollution. A scheme for the classification of the river's chemical status (within the ecological quality classification procedure) was applied by combining pollution parameters in groups according to related pressures. In light of the temporal hydrological regime and anthropogenic impacts, sediment chemical quality elements were considered, in addition to hydrochemical ones. Despite the extensive agricultural activities in the basin, the majority of the sites examined showed a good quality and only three of them were classified as moderate. For the classification of the chemical quality of temporary water bodies, there is a need to develop ecologically relevant salinity and sediment quality standards.

Effects of sampling microhabitats with low coverage within the STAR/AQEM macroinvertebrate sampling protocol on stream assessment

In the STAR/AQEM protocol microhabitats covering less than 5% of the sampling area were neglected. Driven by an ongoing discussion on the importance of these underrepresented microhabitats we tested the influence of sampling them. We investigated 48 streams representing 14 different stream types from all over Germany. Macroinvertebrates of underrepresented microhabitats were sampled in addition to the STAR/AQEM protocol. To ensure the method remains feasible in routine monitoring programmes the total sampling and sorting effort of additional sampling was limited to 20 min. Particularly those taxa were picked, which were not recognised during the routine STAR/AQEM sorting. To identify the effect of additional sampling on stream assessment results, we calculated the stream type-specific Multimetric Index (MMI) with the “main” and the “main+additional” data for each sample. The mean and median difference in MMI values between “main” and “main+additional” samples was 0.02 and 0.01, respectively. In seven of 48 samples (14.6%) a different ecological quality class was calculated with the “main+additional” dataset. Regarding common metrics within the MMI as well as intercalibration metrics differences between “main” and “main+additional” samples were analysed. The values differed most in richness metrics (e.g., number of EPTCBO Taxa, number of Trichoptera Taxa). The results of the present study show that additional sampling of underrepresented microhabitats could alter multimetric assessment results.

The invertebrate species index (ISI) for streams in southeast Queensland, Australia

Abstract The invertebrate species index (ISI) is a new biotic index to assess stream health in southeast Queensland, Australia, using benthic macroinvertebrates. The index aims to refine stream monitoring, in particular for eutrophication, as nutrient input is a major stressor of streams in the region. Biotic indices previously used for the region were based on sensitivity scores for macroinvertebrate families and orders, and were valid for all streams across the continent. The ISI is based on species level and tailored to the specific traits of southeast Queensland, thus yielding an increased level of detection of biological change. This will improve monitoring of environmental impact on a regional and local scale. The ISI is a site-specific index calculated as the weighted average (WA) of species’ sensitivity scores ( S 10 ), with a species-specific indicator weight ( W ) and the abundance ( A ) of each species used as weights. S 10 scores for 203 species of benthic macroinvertebrates ranging from 10 (species most sensitive to pollution) to 1 (tolerant of excessive pollution) were derived by means of WA regression and calibration using site scores representing an environmental impact gradient. W measures the indicator strength of the species, and was derived from the weighted standard deviation of the S 10 . The initial site scores for the WA modeling were derived using canonical correspondence analysis (CCA) to ordinate the sites along a gradient associated with 12 abiotic variables. The data on benthic macroinvertebrates are based on 212 quantitative samples collected in wadeable freshwater streams in southeast Queensland. Two major stream types, (1) small creeks, mainly of uplands and (2) larger streams and rivers of lowlands, were recognised for the region, and for both types the ISI range representing reference condition was established. These reference conditions can be used to establish ecological quality ratios by comparing observed to expected indices and to define ecological quality classes. The ISI is the first biotic index for streams in Australia that uses sensitivity scores and indicator weights for macroinvertebrate species. There is a growing trend in Australia to identify stream macroinvertebrates to species level and to study their specific traits and ecological requirements. The reasons for this are manifold; assessing and monitoring stream health is only one of them. For most regions of Australia, no common ground exists, so far, on how to use species data for stream health assessment. The new biotic index fills this gap for southeast Queensland in providing a standard for the use of species level data in stream health assessment.

Benthic indicators: Analysis of the threshold values of ecological quality classifications for transitional waters

The effect of the modifications of the threshold values generally adopted for the five EcoQ (Ecological Quality) classes recognized by the European Water Framework Directive (WFD) for the most used benthic indicators and diversity indicators (AMBI, BENTIX, BOPA, BQI, H′, ITI and M-AMBI) were studied to test whether it is possible to obtain the same or similar ecological classifications for transitional waters using these different indicators, and determine whether the current classifications can be improved. The analysis included: (i) the use of indicator equations, (ii) the use of reference indicators, and (iii) the use of indicator distribution laws. These investigations demonstrated that it was impossible to obtain an exact intercalibration of the ecological classifications with the selected indicators. However, some propositions to improve the actual classification were suggested.

Assessment of the Ecological Status of Streams in Two Carpathian Subregions

AbstractA multimetric assessment system was developed to determine the ecological status of two types of stream in the Carpathian ecoregion following the requirements of the WFD. The organic pollution gradient was defined using Canonical Correspondence Analysis. Classification based on physical, chemical and biological data divided the tested sites into two stream types with subsequent grouping into several ecological quality classes. From all the metrics tested, 17 for the East Carpathian streams and 15 for the West Carpathian streams, from seven metric categories, were included in the resulting multimetric index. Different kinds of response to degradation (linear, unimodal, exponential) were observed. The Saprobic index (Zelinka and Marvan), Rheoindex (Banning, with abundance classes) and Index of Biocenotic region, showed the best discriminatory ability for both stream types. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Water quality indices across Europe—a comparison of the good ecological status of five river basins

The European Water Framework Directive (WFD) requires the definition of near-natural reference conditions to determine the extent of water bodies' deviation from "good ecological status" caused by stress gradients. However, the classification of ecological quality depends on the assessment method applied and the stressor concerned. While assessment methods that are generally applicable would be favourable, many European countries employ the locally developed water quality metrics that assess the impact of organic pollution (including eutrophication) and the associated decrease in dissolved oxygen. These indices do not specifically address stress from organic toxicants, such as pesticides. The aim of this study was to examine the performance of presently used assessment methods to identify reference conditions of non-contaminated streams in five selected European river basins, covering the geographical region from Spain to Finland, as a crucial prerequisite to indicate toxic gradients. The analysis comprised the Belgium biotic index (BBI), the biological monitoring working party (BMWP) scoring system and the revised German saprobic index. For comparison, we included an adaptation of the recently developed SPEAR index. In two previous field studies, this metric highly correlated with measured pesticide gradients. In this study, SPEAR was the only indicator that was generally applicable to all monitoring data and capable of determining "high ecological status" of reference conditions in all basins. Thus, based upon previous and own results, the authors suggest the species at risk (SPEAR) index to be potentially useful as a European-wide index to address deviations from "good ecological status" due to organic toxicants and recommend it for consideration in integrated water-resource evaluations under the WFD.

The use of macroalgal species richness and composition on intertidal rocky seashores in the assessment of ecological quality under the European Water Framework Directive

The EC Water Framework Directive (WFD) suggests using abundance and species composition of intertidal seaweed communities for ecological quality classification of rocky seashores. There are two difficulties with this. According to WFD all sensitive species should be present on a shore. There is no accepted list of sensitive seaweed species and those which may be sensitive in one location may not be so in another. Second, natural successions can result in very large abundance changes of common species, e.g. from almost completely fucoid-dominated shores to almost totally barnacle-dominated shores, without any change in ecological quality. Studies have shown that numerical species richness, not the list of actual species present, is broadly constant in the absence of disturbance. The ephemeral species, possibly the sensitive members of the community, change regularly in such a way as to conserve species richness. It is proposed that species richness on a defined length of shore be used as a criterion of ecological quality. A database of species found on over 300 shores in the British Isles, under strictly controlled sampling conditions, has given ranges of values of species richness to be expected and has allowed for variations in these values due to sub-habitat variability, wave exposure and turbidity to be factored in. A major problem in applying such a tool is the lack of expertise of many workers in critical identification of seaweed species. A reduced species list has been extracted from the database using species commonly present and identifiable with reasonable certainty. A numerical index of ecological quality is proposed based on scores for various aspects of the physical nature of the habitat combined with a score for species richness which may be based on the reduced species list. The scoring system also uses further aspects of community structure, such as ecological status groups and the proportions of rhodophyta, chlorophyta and opportunist species. For this system to be effective there has to be close control of the way in which sampling is carried out to ensure a uniform level of thoroughness.

Benthic biodiversity indices versus salinity gradient in the southern Baltic Sea

The need to assess the environmental status of marine and coastal waters according to the EU Water Framework Directive (WFD) encouraged the design of specific biotic indices to evaluate the response of benthic communities to human-induced changes in water quality. In the present study three of these indices, the traditional Shannon Wiener Index (H′) and the more recently published AMBI (AZTI′ Marine Biotic Index) and BQI (Benthic Quality Index), were tested along a salinity gradient in the southern Baltic Sea. The comparison of the three indices demonstrates that in the southern Baltic Sea the ecological quality (EcoQ) classification based on macrozoobenthic communities as indicator greatly depends on the biotic index chosen. We found a significant positive relation between species number, H′, BQI and salinity resulting in EcoQ status of “Bad”, “Poor” or “Moderate” in areas with a salinity value below 10 psu. The AMBI was less dependent on salinity but appear to partly overestimate the EcoQ status. Presently none of these biotic indices appear to be adjusted for application in a gradient system as given in the southern Baltic Sea. A potential approach describing how to overcome this limitation is discussed.

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).

Direct comparison of assessment methods using benthic macroinvertebrates: a contribution to the EU Water Framework Directive intercalibration exercise

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.

Beyond Masses and Blooms: The Indicative Value of Oligochaetes

The European Water Framework Directive (WFD) defines a framework for assessing water bodies in Europe in the future. The conditions in the Directive impose a strong demand for “new” assessment systems. The AQEM project developed an assessment system for European streams using macroinvertebrates. Almost 900 samples were taken in about 400 streams covering 29 stream types distributed over eight countries. The role of the Oligochaeta within this European database was analysed. Almost half a million specimens of oligochaetes were collected in 772 samples. Eight families, 41 genera and 69 species were recorded, although identification emphasised the families Tubificidae and Naididae. Three countries identified oligochaetes to species level, most others restricted their identifications to easy identifiable taxa. Numbers of specimens, species, genera and families differed strongly between the countries due to method, although standardised, and taxonomic knowledge. About 50% of all collected oligochaete taxa had assigned biological and ecological indicator values for metric calculation in the AQEM assessment system. A further refinement of this indication list as well as increased coverage of oligochaete taxa was advised. Weighted averaging was used to evaluate the relation between oligochaete distribution and ecological quality class. It was concluded that when higher taxonomic levels are used in assessment, the quality evaluation results become biased. Furthermore, oligochaetes can tell us much more about the ecological status of streams than is commonly assumed. Differences in ecological optima among Limnodrilus udekemianus, Ilyodrilus templetoni, Aulodrilus pluriseta, Nais communis, and Spirosperma ferox are shown.

The use of a biotic index (Bentix) in assessing long-term effects of dumping coarse metalliferous waste on soft bottom benthic communities

Abstract The biotic index Bentix [Simboura, N., Zenetos, A., 2002. Benthic indicators to use in Ecological Quality classification of Mediterranean soft bottom marine ecosystems, including a new biotic index. Mediterr. Mar. Sci., 3 (2), 77–111] developed for the classification of ecological status of zoobenthic communities was tested in a Mediterranean coastal area (Aegean Sea, N. Evvoikos gulf, Greece) subject to coarse metalliferous waste discharge. The residues in the form of slag are the byproducts of the smelting procedure of a local ferronickel plant and are discharged in a permitted area 8 km from the shore. This practice adopted over the last 36 years has led to the formation of a thick underwater deposit of slag on the sea bottom. A decade of monitoring resulted to a long series of data on macrozoobenthos communities in the area. Application of the Bentix and other indices on the data has revealed the long-term impact of dumping on the benthic communities and the potential of the indices used to assess the community health. Among the indices tested, Bentix index succeeded in assessing the long-term trends of decline or recovery of the community health. The index proved efficient in detecting differences of the ecological status of the communities attributed to the transferring of the core of the dumping activity over the area studied, as validated by the geophysical data provided.