Robustness of the biotic indicators used for classification of ecological status of lotic water bodies: A testing method when the data series are short

Successful implementation of the Water Framework Directive and achieving its objective of good ecological status of all water bodies depend on the power of the set of monitoring indicators to capture the change in the ecological status of aquatic systems. In this context, testing the robustness and sensitivity of ecological indicators currently used for assessing the status of lotic water bodies is instrumental for the adaptation and further development of assessment methods. This is also a prerequisite for an effective, context-based monitoring system and for improving the quality of the decision making for water bodies. This is particularly challenging in regions where the sets of indicators are under development, the data series are relatively short and data which addresses the individual error sources are lacking. Here we show that hierarchical clusters and ordination analysis provide appropriate tools with which the validity of the ecological status of water bodies set up based on biological multimetric monitoring indices in a small water basin could be tested. We hypothesize that robust and informative monitoring methods classify all water bodies belonging to a single ordination grouping in the same quality class (high, good, moderate, poor or bad). In our case study multimetric biological indicators failed to discriminate between the good and moderate ecological status. Community structure as well as water conductivity and nitrate load were primarily responsible for the observed difference between ordination groupings. Inconsistencies shown in our case study are likely to be induced by insufficient refinement of monitoring schemes and by the constraints existing in the data series and available metadata. We show that multiplication of indicators leads to discrepant interpretation and problematic application. Proposed ordination analysis proves to be a simple and useful tool to detect such discrepancies and support further progress in indicator development. Integrated and longer data and metadata series are needed to refine context-based monitoring methods.     

Geomorphology variables predict fish assemblages for forested and endorheic rivers of two continents

Stream fishes are restricted to specific environments with appropriate habitats for feeding and reproduction. Interactions between streams and surrounding landscapes influence the availability and type of fish habitat, nutrient concentrations, suspended solids, and substrate composition. Valley width and gradient are geomorphological variables that influence the frequency and intensity that a stream interacts with the surrounding landscape. For example, in constrained valleys, canyon walls are steeply sloped and valleys are narrow, limiting the movement of water into riparian zones. Wide valleys have long, flat floodplains that are inundated with high discharge. We tested for differences in fish assemblages with geomorphology variation among stream sites. We selected rivers in similar forested and endorheic ecoregion types of the United States and Mongolia. Sites where we collected were defined as geomorphologically unique river segments (i.e., functional process zones; FPZs) using an automated ArcGIS‐based tool. This tool extracts geomorphic variables at the valley and catchment scales and uses them to cluster stream segments based on their similarity. We collected a representative fish sample from replicates of FPZs. Then, we used constrained ordinations to determine whether river geomorphology could predict fish assemblage variation. Our constrained ordination approach using geomorphology to predict fish assemblages resulted in significance using fish taxonomy and traits in several watersheds. The watersheds where constrained ordinations were not successful were next analyzed with unconstrained ordinations to examine patterns among fish taxonomy and traits with geomorphology variables. Common geomorphology variables as predictors for taxonomic fish assemblages were river gradient, valley width, and valley slope. Significant geomorphology predictors of functional traits were valley width‐to‐floor width ratio, elevation, gradient, and channel sinuosity. These results provide evidence that fish assemblages respond similarly and strongly to geomorphic variables on two continents.     

Modification of an index of biotic integrity based on fish assemblages to characterize rivers of the Seine Basin,France

The Index of Biotic Integrity (IBI) is a measure of fish assemblage health that has been used to assess catchment and stream quality throughout North America. It reflects human perturbations on natural environmental structures and processes. While preserving the ecological foundation of the original North American metrics, we have modified and adapted the IBI to the mainstem Seine River and its major tributaries in France. This successful modification of the IBI to a considerably different fish fauna on a different continent further supports its wider use outside the midwestern United States. Using data collected in 1967, 1981, and 1988–1989 from a total of 46 sites, we show spatial and temporal variation in the Seine as indicated by IBI scores. Statistically significant relationships were found between IBI and catchment area but insignificant relationships existed between IBI and an independent Water Quality Index (WQI) based on water chemistry. Comparisons between the IBI and the WQI indicate that the former is a more sensitive and robust measure of water body quality. Our results demonstrate that the IBI, combined with a statistically designed national monitoring program, would offer a reliable means of assessing spatial patterns and temporal trends in water body improvement or degradation in France. The more primitive fish families in the Basin were affected first by perturbations. These families include all the diadromous species found in the Seine and suggest serious disruption of their life histories.     

An advanced Index of Biotic Integrity for use in tropical shallow lowland streams in Costa Rica: Fish assemblages as indicators of stream ecosystem health

This paper presents an advanced version of the Index of Biotic Integrity (IBI), a multimetric index to indicate ecosystem health. The multimetric index has been adapted in such a way that it not only indicates overall condition but also specific causes of environmental disturbance. The newly developed index (a) uses data of tolerant as well as intolerant species in a single metric to indicate environmental disturbance, (b) does not require knowledge about species from the literature, and (c) can be applied to artificial landscapes.The metrics proposed here consist of indicator species assemblages that are selected directly for their relationship with an environmental component or specific type of environmental degradation. Thus, each metric indicates a type of environmental concern, which enables conservation practices to be targeted more effectively. Species assemblages for each single metric consist of a combination of species that can be negatively and positively related to environmental disturbances, providing a better indication of stream ecosystem health.The area studied was assumed to be too diverse for one single index. Canonical Indirect-Gradient Principal Component Analysis indicated that the optimal division of subindices based on stream typology was for streams with drainage basin sizes <10 km² and >10 km². Pearson Product-Moment Correlations were used to identify relationships between anthropogenic disturbances and the composition and abundance of fish species at impacted as well as undisturbed sites. This index proved to be useful for indicating overall stream ecosystem health as well as local onsite environmental disturbances or the environmental components of greatest concern. This index does require extensive information about measured levels of anthropogenic disturbances with the accompanying composition and abundance of fish species.     

A fourteen-year overview of the fish assemblages and yield of the two oldest Algarve artificial reefs (southern Portugal)

Artificial reefs have been deployed worldwide for the last three decades in response to problems concerning coastal resources, ecosystems and fisheries. In many countries they have became important elements of integrated fisheries management plans. In Portugal two artificial reef systems (ARSs) were deployed by the Portuguese Institute of Marine Research (IPIMAR) in 1990, in the southern coast (Algarve). They were located off Faro and Olhão, over different sea-bottom types and located at different distances from the coastline. To analyse the effect of ARSs deployment on local fish assemblages and to evaluate their effectiveness in terms of mean fishing yields and mean number of species caught, fishing surveys have been conducted over 14 years (256 net sets) using a gillnet to sample the ARS of Faro and Olhão and respective control sites. The fishing yields from the ARs continually exceeded those from the control sites, in both the mean number of species caught and the mean CPUE in weight (1.8–2.6 times); both were higher at Faro. Moreover, the comparison between fish assemblages from the ARS and respective control sites showed that the deployment of the man-made structures did not change the composition of the fish assemblages caught by the gill nets, or the equilibrium of the community, since the relative proportion of the different functional groups of fish remained stable. The ARSs are a useful management tool on the Algarve coast, enhancing and diversifying the catches, thus contributing to improved local artisanal fisheries, which play a major role in this region.     

An index of biotic integrity based on fish assemblages for subtropical streams in southern Brazil

Several methods for calculating indices of biological integrity (IBIs) have been developed for different ecogeographic regions of the world. All of them calculate IBI scores by comparing against reference sites or historical data on fish assemblage composition. Because of intensive agriculture and urbanization in our study area, we located no reference sites, and historical information about fish assemblage composition did not exist. Instead, we developed hypothetical reference scores based on seasonal electrofishing surveys at six study sites in adjacent but geomorphologically different watersheds. Our IBI included 10 metrics that varied with degree of degradation. We found that Shannon–Wiener indices varied significantly between seasons, indicating significant changes in species composition. Therefore, we calculated seasonal IBI scores also, but these did not significantly differ from each streams general IBI score, which was calculated on the basis of four samples per site. General stream IBI scores reflected differing levels of anthropogenic disturbance.     

Seasonal variation in the composition of fish assemblages in small Amazonian forest streams: evidence for predictable changes

1. The effects of seasonal inundation on the biology of fishes on floodplains of large Amazonian rivers are well studied. However, the small seasonal changes in headwater streams are generally considered to have little effect on fish assemblages. 2. In this study, we analysed seasonal changes in the species composition and abundance of fish in small Amazonian forest streams. We sampled fish with hand and seine nets in headwater streams in a 10 000 ha terra‐firme forest reserve near Manaus, Brazil. Each stream was surveyed at the end of the 2005 dry season, at the beginning of the 2006 rainy season and at the beginning of the 2006 dry season, by means of a standardized sampling effort. 3. The numbers of individuals and species caught were higher in the dry season, but rarefaction analyses indicated that greater species numbers could have been due simply to the larger number of individuals caught. 4. Between the dry and rainy season, the direction of changes in species composition in multivariate space varied among sites, especially for quantitative (abundance) data. However, the observed variation among sites was the less than expected if the directions of change were random. 5. Fish assemblages in the second dry season were more similar to those in the previous dry season than expected if changes in species composition among seasons were random. This indicates that a general seasonal pattern in fish assemblages can be detected, despite the existence of some erratic site‐specific changes. 6. Most of the species that showed large seasonal variations in density occupy temporary ponds during the rainy season, when much of the valley is inundated and pond networks form adjacent to streams. Short‐duration lateral migrations to these ponds may play an important role in the seasonal fish‐assemblage dynamics in Amazonian headwater streams. 7. Our results contrast with previous studies on small Amazonian streams, which have found little seasonal change in fish assemblages, and highlight the importance of the abundance of common species as an indicator of general fish assemblage structure in biological monitoring programmes.     

Impacts of past glaciation events on contemporary fish assemblages of the Ohio River basin

Aim We evaluated variation in fish assemblages on the basis of taxonomic composition and functional groups based on Pleistocene glacial boundaries in the Ohio River basin. We tested for the influence of habitat and hydrology on fish assemblage variation. Location Ohio River basin of North America, including the states of Ohio, Indiana and Illinois. Methods Fish collection sites were identified as Wisconsinan, pre‐Wisconsinan or unglaciated regions. Multivariate analyses, multi‐response permutation procedures, discriminant analysis and indicator species analyses were used to test whether taxonomic and functional assemblages were distinct among regions with varying glacial histories. Principal components analysis was used to identify habitat and water quality, as well as hydrological gradients that could be discerned by glacial region. Results We identified significant differences in both taxonomic and functional fish assemblage structure and habitat variation among regions that had different glaciation histories. The largest differences in taxonomic and functionally based fish communities were for unglaciated and pre‐Wisconsinan regions, while unglaciated and Wisconsinan regions were most similar. We correctly classified study regions in 71% and 60% of sites using taxonomy and functional analyses, respectively. Wisconsinan sites were characterized by Cyprinidae and Catostomidae assemblages with high abundances of tolerant fishes that tended to occur in habitats with reduced current velocity. Pre‐Wisconsinan sites were characterized by Cyprinidae, Catostomidae, Centrarchidae and Percidae families with increased abundances of intolerant fishes that tended to occur in habitats with coarser substrates and increased water velocity in streams of varying size. Unglaciated sites were characterized by Cyprinidae and Percidae families and were not closely associated with any habitat‐based functional group. Habitat in the unglaciated and pre‐Wisconsinan sites was significantly different from that in the Wisconsinan sites, which were characterized by increased channel structure and reduced stream size. Main conclusions Pleistocene glaciation events formed a lasting template of predictable regional differences in stream habitat and in the corresponding taxonomic and functional fish assemblage structures. While many factors impact the distribution of fishes, these results suggest that historical influences such as glaciation may be used to further explain the underlying mechanisms of spatial variation in fish assemblages.     

An evaluation framework based on sustainability-related indicators for the comparison of conceptual approaches for ecological networks

Ecological networks (EN) are designed to maintain biodiversity and ecological processes by protecting habitats and their linkages. By considering the functional role of the landscape, EN can support the integration of ecological sustainability with human activities. Although all EN share the same general objectives, there are many different approaches for determining the spatial configuration of their components. The choice of an approach for the design of an EN has a major impact on the spatial configuration, ecological value, and ease of implementation of the resulting network. We applied different approaches to construct EN for the Saint-François River watershed (8700 km²) in southern Quebec, Canada. The approaches were based on single-species, multi-species, and landscape modeling categories. All of the resulting EN were evaluated using ecological, economic, and social spatial thematic indicators (TI) relevant to sustainable landscape management. This allowed us to quantitatively assess the impact of each approach and to establish their relative performance within a common framework. Our results showed that the conceptual approach for EN has a direct influence on their spatial configuration and performance. Single-species-, multi-species- and landscape-based categories produced very different EN. These results emphasize the importance of the selection of focal species and/or key environments for the design of EN. Our results also highlight the importance of adequately defining the desired objectives and expected functions of an EN, knowing that the results of the conceptual approach will be modified depending on the environment. Results are discussed in relation to the objectives sought by the implementation of the EN, spatial scale, and land use. Our evaluation framework is a useful tool for mitigating uncertainties associated with EN by facilitating the integration of stakeholders’ priorities and landscape management objectives.     

Effects of coalbed natural gas development on fish assemblages in tributary streams of the Powder and Tongue rivers

1. Extraction of coalbed natural gas (CBNG) often results in disposal of large quantities of CBNG product water, which may affect aquatic ecosystems. We evaluated the effects of CBNG development on fish assemblages in tributary streams of the Powder and Tongue rivers. We used treatment and control, impact versus reference sites comparisons, surveys of CBNG product‐water streams and in situ fish survival approaches to determine if CBNG development affected fish assemblages. 2. Several of our results suggested that CBNG development did not affect fish assemblages. Species richness and index of biotic integrity (IBI) scores were similar in streams with and streams without CBNG development, and overall biotic integrity was not related to the number or density of CBNG wells. Fish occurred in one stream that was composed largely or entirely of CBNG product water. Sentinel fish survived in cages at treatment sites where no or few fish were captured, suggesting that factors such as lack of stream connectivity rather than water quality limited fish abundance at these sites. Fish species richness did not differ significantly from 1994 to 2006 in comparisons of CBNG‐developed and undeveloped streams. Biotic integrity declined from 1994 to 2006; however, declines occurred at both impact and reference sites, possibly because of long‐term drought. 3. Some evidence suggested that CBNG development negatively affected fish assemblages, or may do so over time. Specific conductivity was on average higher in treatment streams and was negatively related to biotic integrity. Four IBI species richness metrics were negatively correlated with the number or density of CBNG wells in the catchment above sampling sites. Bicarbonate, one of the primary ions in product water, was significantly higher in developed streams and may have limited abundance of longnose dace (Rhinichthys cataractae). Total dissolved solids, alkalinity, magnesium and sulphate were significantly higher in developed streams. 4. Biological monitoring conducted before the development of CBNG, and continuing through the life of development and reclamation, together with data on the quantity, quality and fate of CBNG product water will allow robust assessment of potential effects of future CBNG development worldwide.     

Development and application of benthic macroinvertebrate-based multimetric indices for the assessment of streams and rivers in the Taihu Basin,China

The development of biological indicators for assessing ecological conditions in streams and rivers is urgently needed in China, particularly in heavily impacted regions. The aim of this study was to develop and apply benthic macroinvertebrate-based multimetric indices (MMIs) for the assessment of streams and rivers in the western hill and eastern plain aquatic ecoregions of the Taihu Basin. MMIs were based on samples collected from October 16 to November 8 2012 at 120 sites in streams and rivers. Least disturbed sites defined the reference conditions. Chemical water quality, physical habitat, and land use were used as criteria to identify reference sites in the basin. Metrics related to benthic macroinvertebrate richness, composition, diversity and evenness, pollution tolerance, and functional feeding groups were screened by range, sensitivity, responsiveness, and redundancy tests. Total number of taxa; percentage of Ephemeroptera, Trichoptera and Odonata (% ETO); Berger–Parker’s index (BP); Biotic index (BI); and percentage of filterers–collectors (% FC) were used to construct the MMI for the western hill aquatic ecoregion (MMI_W). Total number of taxa, percentage of Crustacea and Odonata (% CO), BP, BI, and % FC were used to construct the MMI for the eastern plain aquatic ecoregion (MMI_E). The MMI scores were obtained by combining the rating categories (excellent, good, fair, poor, and very poor). The MMIs were tested using a separate subset of the data, and the results indicated that the newly developed MMIs were robust in terms of percentage of sites correctly classified, coefficient of variation, box-separation ratios, and separation powers. The ecological status was then evaluated based on the MMI scores. The results indicated that the general ecological status of streams and rivers in the Taihu Basin was rated lower than “good”, the western hill aquatic ecoregion was rated “fair” and the eastern plain aquatic ecoregion was rated “poor”. Moreover, the MMIs showed a significant negative response to an increasing gradient of disturbance. Therefore, these preliminary MMIs can be used as assessment tools in ecological biomonitoring and management of the Taihu Basin.     

An approach to intercalibrate ecological classification tools using fish in transitional water of the North East Atlantic

A simple procedure to harmonise and intercalibrate eight national methods classifying the ecological status using fish in transitional waters of the North East Atlantic is described. These methods were initially intercalibrated and a new method recently developed was added to this exercise. A common human pressure index pre-classified the status of each water body in an independent way. Ecological class boundaries values were established according to the level of anthropogenic pressure using regression analyses. A simulated dataset was used to assess the level of agreement between the fish classification methods. Fleiss’ multi-rater kappa analysis indicated that boundary harmonisation was achieved; all classifications fell within one class of each other and class agreement between methods exceeded 70%. The use of a pressure index to establish boundary thresholds provides a practical method of defining and harmonizing the quality classes associated with human pressures, as required by the European Water Framework Directive.     

Otters and fish farms in the Sado estuary: ecological and socio-economic basis of a conflict

The degree of conflict between otter conservation and fish farming was assessed at Sado estuary (SW Portugal), using ecological (otter visiting rates to fish farms and consumption of commercial fish) and socio-economic (past and current instruments and policies addressing the conflict and a social impact assessment, including a discourse analysis of relevant stakeholders) parameters. The study concerned 14 fish farms producing Sparus aurata, Dicentrarchus labrax, Solea senegalensis and Solea solea. Results indicate high visiting rates in most fish farms (average: 76%), although in only 29%, species stocked were the most consumed prey. Other marine species and freshwater prey were the basis of otter diet in the remaining fish farms. The conflict is quite consensual among most fish farmers, and the results indicate that the perceived conflict by fish farmers has an ecological basis, although there are large gaps between effective and perceived predation. No specific instruments exist in Portugal to address the conflict, but some not specifically targeted can have an effect (e.g. species protection legislation and aquaculture licensing), although with limitations to effectively contribute to its mitigation (e.g. lack of enforcement and supervision). Formulating and assessing solutions is the following step, using a participatory approach to the development and evaluation of mitigation/compensation strategies, capable of providing an effective reconciliation of the conflict.

集成的专家系统和神经网络应用于大熊猫生境评价

充分了解大熊猫生境的时空格局及其变化,对有效保护大熊猫非常重要.绘制生境图既是野生动物生境评价和监测的一个有效方式,也是一个必要的步骤.新发展起来的人工智能方法(包括专家系统和神经网络方法),在模拟复杂系统过程中能够同时综合定性和定量信息,并可集成于GIS中,有助于大熊猫复杂生境的制图及评价.为了对大熊猫生境进行评价,本文建立了一个较全面的综合制图方法,将专家系统、神经网络和多类型数据全部集成在GIS环境下.结果表明,采用专家系统和神经网络集成方法绘制的大熊猫生境图的精度达到80％以上,高于单一的专家系统方法、神经网络方法和传统的最大似然法制图的精度.Z统计方法也证实了新建立的专家系统和神经网络集成方法要显著好于3种单一方法.     

A method for prioritizing the reestablishment of river continuity in Austrian rivers

River continuity is one of the hydro-morphological elements supporting the classification of the ecological status of rivers. In order to achieve good ecological status in the continuity of rivers, the impacts of anthropogenic activities must be limited to the extent that some fish age classes may be missing and there may only be slight changes in species composition and abundance from the type specific community. The main goal of the project is to list priorities for removing obstruction to migration within 12 years to reestablish river continuity so as to allow undisturbed migration of aquatic organisms. The ecological status of the river, the cost–benefit ratio of the proposed restoration and the distance between obstructions are analysed. More than 200 obstructions in about 170 km of river were evaluated. A 1st ranking of the parameter “extension of undisturbed river length” shows significant alterations in comparison with the 2nd and 3rd ranking, where the river length is weighted over the parameters “ecological status” of the river reach and the “cost–benefit ratio” of the measure. The ecological status is classified by comparing the present versus the potential natural morphological conditions (Leitbild). The cost–benefit ratio takes into account the increase of the fish species composition and the cost of the measures in relation to local circumstances of available property and height of the drop. Examples of obstructions in the Pinka R. move back in the priority list to a maximum of −9 places and forwards to a maximum of +8 places. As a result the list of obstructions by priority for removal to be removed first at the top is analysed. The financial policy and a schedule for removal for the period 2003–2015 are based upon the results of the priority list. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Guest editors: R. L. Welcomme & G. Marmulla Hydropower, Flood Control and Water Abstraction: Implications for Fish and Fisheries     

Trait‐based diatom functional diversity as an appropriate tool for understanding the effects of environmental changes in soda pans

Saline lakes, among the most seriously endangered ecosystems, are threatened due to climate change and human activities. One valuable feature of these environments is that they constitute areas of high biodiversity. Ecologists are, therefore, under great pressure to improve their understanding of the effects of natural and anthropogenic disturbances on the biodiversity of saline lakes. In this study, a total of 257 samples from 32 soda pans in Central Europe between 2006 and 2015 were examined. The effects of environmental variables and of geographical and limnoecological factors on functional diversity were analyzed. Furthermore, the explanatory power of the trait‐based approach was assessed, and the applicability of the indices for biomonitoring purposes was determined. It was found that low habitat heterogeneity and harsh environments lead to the selection of a small number of suitable traits, and consequently, to a naturally low level of functional diversity. Anthropogenic activities enhance diversity at functional level due to the shift toward freshwater characteristics. On the regional scale, the effects of the region and status (natural, degraded, reconstructed) on diatom functional diversity were significant and more pronounced than that of the environmental and other limnoecological factors. The degree of variance found in functional diversity ascribed to environmental variables is five times greater in the case of the application of a trait‐based approach, than when a taxonomic one is employed in the literature. Each of the tested functional diversity indices was sensitive to the most important environmental variables. Furthermore, these were type‐specific and proved to be more complex indicators than taxonomic metrics. It is possible to suggest four functional diversity indices (FGR, FRic, FDis, and FDiv) which emphasize their independence from substrate and seasonal variations for ecological status assessment and conservation planning.     

An easy-to-use index of ecological integrity for prioritizing freshwater sites and for assessing habitat quality

Prioritizing and assessing the condition of sites for conservation action requires robust and ergonomic methodological tools. We focus here on prioritizing freshwater sites using two promising biodiversity indices, the Dragonfly Biotic Index (DBI) and Average Taxonomic Distinctness (AvTD). The AvTD had no significant association with either species richness or endemism. In contrast, the DBI was highly significantly associated with species richness and endemism, although the strengths of the associations were weak. These associations are related to how the sub-indices in the DBI are weighted, and how species are distributed geographically. Additionally, the DBI was found to be very useful for site selection based on its ability to measure ecological integrity, combined with level of threat, at multiple spatial scales. The AvTD was found to be useful principally for regional use. As the DBI is a low-cost, easy-to-use method, it has the additional use as a method for assessing habitat quality and recovery in restoration programs. The DBI operates at the species level, and is therefore highly sensitive to habitat condition and has great potential for environmental assessment and monitoring freshwater biodiversity and quality. Practical, worked examples of river restoration are given here. In view of the ease and versatility by which the DBI can be employed, we recommend its testing and possible integration into freshwater management and conservation schemes elsewhere in the world.     

An expert system to estimate the pesticide contamination of small streams using benthic macroinvertebrates as bioindicators II. The knowledge base of LIMPACT

The development and the evaluation of a biological indicator system for pesticide pollution in streams are presented. For small headwater streams with an agricultural catchment area, the expert system LIMPACT estimates the pesticide contamination according to the four classes: Not Detected (ND), Low (L), Moderate (M) and High (H) contamination without any specification of the chemical agents. The input parameters are the abundance data of benthic macroinvertebrate taxa within four time frames in a year (March/April, May/June, July/August, September/October) and nine basic water-quality and morphological parameters. The heuristic knowledge base was developed with the shell-kit D3 and contains 921 diagnostic rules with scores either to establish or to de-establish a diagnosis. The 418 rules had less than three symptoms, and only 47 rules had more than four symptoms in their rule condition. We differentiate between positive indicator (PI) taxa, which indicate contamination by high abundance values and positive abundance dynamics, and negative indicator (NI) taxa, a high abundance of which rules out contamination and indicates an uncontaminated site. We analysed 39 taxa and found 13 positive and 24 negative indicators. The database comprises 157 investigations per stream and year with rainfall event-controlled pesticide sampling and repeated benthic sampling as described in Part 1 [Ecol. Indicators, this issue]. For the evaluation of LIMPACT, we used the same cases. The correct class for the 157 investigations per stream and year is established by LIMPACT in 66.7–85.5% of the cases, with better results for uncontaminated sites. The overall alpha error probability (false positive) is 9.6% while the beta error probability (false negative) varied between 0 and 8% depending on the contamination class. If each stream is considered only once in the system (n=104), the correct diagnosis is established by LIMPACT in 51.9–88.6% of the cases. In most of the remaining cases no diagnosis is established instead of a wrong one.