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Uncertainty is an important factor in ecological assessment, and has important implications for the ecological classification and management of lakes. However, our knowledge of the effects of uncertainty in the assessment of different ecological indicators is limited. Here, we used data from a standardized campaign of aquatic plant surveys, in 28 lakes from 10 European countries, to assess variation in macrophyte metrics across a set of nested spatial scales: countries, lakes, sampling stations, replicate transects, and replicate samples at two depth-zones. Metrics investigated in each transect included taxa richness, maximum depth of colonisation and two indicators of trophic status: Ellenberg's N and a metric based on phosphorus trophic status. Metrics were found to have a slightly stronger relationship to pressures when they were calculated on abundance data compared to presence/absence data. Eutrophication metrics based on helophytes were found not to be useful in assessing the effects of nutrient pressure. These metrics were also found to vary with the depth of sampling, with shallower taxa representing higher trophic status. This study demonstrates the complex spatial variability in macrophyte communities, the effect of this variability on the metrics, and the implications to water managers, especially in relation to survey design. [ABSTRACT FROM AUTHOR]

Abstract: During the last decade multimetric indices (MMIs) have been greatly improved by the use of appropriate criteria to define reference conditions and by the use of statistical analysis to select a consistent set of metrics. Among the large number of MMIs developed to assess the ecological status of streams based on fish communities, the emphasis was mainly put on warmwater assemblages. When compared with warmwater fish assemblages, coldwater assemblages present depauperate faunas with a limited suit of traits. Thus, very often the number of metrics used to compute MMIs for coldwater streams is lower than for warmwaters. The objective of this study was to develop new metrics specific to European coldwater assemblages that integrate both the species traits and the body size of fish. Indeed, whereas the use of size or age classes has been highly advocated for developing MMIs, it remains largely underrepresented. Therefore, we used eight biological and ecological traits to characterize species and two size classes: small and large individuals. Among the 96 metrics tested, four were successfully related to environmental gradients and three displayed a significant response to anthropogenic pressures: the number of small rheophilous individuals, the number of small oxygen-intolerant individuals, and the number of small-habitat-intolerant individuals. These results demonstrate that metrics based on size classes could be used in the development of MMIs for coldwater streams and more generally for low-species rivers. [Copyright &y& Elsevier]

Abstract: A procedure for a large scale harmonization of assessment systems is delineated. The data collected for the two E.U. co-funded projects STAR and AQEM have been used as a benchmark dataset against which a test dataset derived from Italian standard monitoring programs was compared. A central step in the procedure adopted is the calculation of Intercalibration Common Metrics (STAR_ICMs). For both the benchmark and test datasets, six metrics were calculated, normalized and averaged to obtain an ICM index. The median values obtained for this index within each of the High and Good status classes, as defined within the STAR/AQEM dataset, were compared to the classes defined by the National method applied in Italy before WFD approval. The process of harmonization involved the re-positioning of the boundaries between Italian method quality classes until no more differences were found with the values observed in the STAR/AQEM samples. The re-setting of the Italian assessment boundaries by a step-by-step procedure lead to comparable STAR_ICM index values in the two datasets. Within this example, small refinements of the boundaries between high/good and good/moderate status were sufficient to harmonize the Italian assessment quality classes to the benchmark classification. Once a benchmark dataset is agreed among different countries, the procedure outlined can be easily applied to compare and harmonize assessment systems within and outside Europe. The main scientific and practical advantages of the procedure are listed and commented, especially facing the next steps of the Water Framework Directive Intercalibration process. [Copyright &y& Elsevier]

This short paper summarises the information developed in the EU funded research project STAR on autecology databases, metrics, multimetrics and community approaches. For Europe the WFD implementation gave an important stimulus for the development of ecology based assessment techniques. Along with the development of metrics and multimetrics indices taxalists and autecological information were strongly improved. Recommendations are given to further develop ecological assessment in European streams and rivers. [ABSTRACT FROM AUTHOR]