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Based on the ‘European Mires Book’ of the International Mire Conservation Group (IMCG), this article provides a composite map of national datasets as the first comprehensive peatland map for the whole of Europe. We also present estimates of the extent of peatlands and mires in each European country individually and for the entire continent. A minimum peat thickness criterion has not been strictly applied, to allow for (often historically determined) country-specific definitions. Our ‘peatland’ concept includes all ‘mires’, which are peatlands where peat is being formed. The map was constructed by merging national datasets in GIS while maintaining the mapping scales of the original input data. This ‘bottom-up’ approach indicates that the overall area of peatland in Europe is 593,727 km². Mires were found to cover more than 320,000 km² (around 54 % of the total peatland area). If shallow-peat lands (< 30 cm peat) in European Russia are also taken into account, the total peatland area in Europe is more than 1,000,000 km2 , which is almost 10 % of the total surface area. Composite inventories of national peatland information, as presented here for Europe, may serve to identify gaps and priority areas for field survey, and help to cross-check and calibrate remote sensing based mapping approaches.

Based on the ‘European Mires Book’ of the International Mire Conservation Group (IMCG), this article provides a composite map of national datasets as the first comprehensive peatland map for the whole of Europe. We also present estimates of the extent of peatlands and mires in each European country individually and for the entire continent. A minimum peat thickness criterion has not been strictly applied, to allow for (often historically determined) country-specific definitions. Our ‘peatland’ concept includes all ‘mires’, which are peatlands where peat is being formed. The map was constructed by merging national datasets in GIS while maintaining the mapping scales of the original input data. This ‘bottom-up’ approach indicates that the overall area of peatland in Europe is 593,727 km2. Mires were found to cover more than 320,000 km2 (around 54 % of the total peatland area). If shallow-peat lands (< 30 cm peat) in European Russia are also taken into account, the total peatland area in Europe is more than 1,000,000 km2 which is almost 10 % of the total surface area. Composite inventories of national peatland information, as presented here for Europe, may serve to identify gaps and priority areas for field survey, and help to cross-check and calibrate remote sensing based mapping approaches.

The Water Framework Directive (WFD 2000) defines macrophytes as one of the biological groups required for the ecological assessment of European surface waters. Several indices for macrophyte assessment have been proposed or are currently in use by different European states. As a first step towards performing an intercalibration of these indices a common dataset was developed. This dataset contains abundance data on 789 macrophyte species from 316 different lake sites in ten European countries. Various common species and genera were identified as indicators of reference and impacted conditions within the dataset. Cluster analysis of macrophyte data, supported by non-metric multidimensional scaling, indicated that clusters formed were more reflective of their source country rather than lake type. This might be caused by differences in regional climate, biogeography, monitoring techniques, or a combination of these factors. A total of six national indices were applied to assign quality classes to the lakes. However, this produced results that often differed by one or two quality classes for the same site. We foresee that a more precise intercalibration exercise is necessary, and it should be based on more detailed data considering both seasonality and the latitudinal differences within the area covered., The Water Framework Directive (WFD 2000) defines macrophytes as one of the biological groups required for the ecological assessment of European surface waters. Several indices for macrophyte assessment have been proposed or are currently in use by different European states. As a first step towards performing an intercalibration of these indices a common dataset was developed. This dataset contains abundance data on 789 macrophyte species from 316 different lake sites in ten European countries. Various common species and genera were identified as indicators of reference and impacted conditions within the dataset. Cluster analysis of macrophyte data, supported by non-metric multidimensional scaling, indicated that clusters formed were more reflective of their source country rather than lake type. This might be caused by differences in regional climate, biogeography, monitoring techniques, or a combination of these factors. A total of six national indices were applied to assign quality classes to the lakes. However, this produced results that often differed by one or two quality classes for the same site. We foresee that a more precise intercalibration exercise is necessary, and it should be based on more detailed data considering both seasonality and the latitudinal differences within the area covered.

There are over 300 lakes interconnected by riverbranches and man-made canals in the Danube Delta (Romania). A multidisciplinary survey of these riverine lakes situated in large wetland complexes was made comprising hydrological modelling, remote sensing and monitoring of water quality, plankton, aquatic vegetation and fish communities. Between-lake differences in water quality and aquatic vegetation cover were inferred from satellite image. Based on channel and lake dimensions, hydrological characteristics of the lakes in the delta were determined: hydrological distance from a riverbranch, residence time and impact of reed water. Water-quality and biotic parameters (phyto- and zooplankton, submerged plants and fish) were sampled in a comparative survey in June 1997-1999 in subsets of the lakes. In a follow-up study in 2001-2002, seasonality of aquatic vegetation and fish were recorded. A clear distinction was found in three lake types: (1) inflow lakes at short distance to the river, with a high flushing rate, high load of suspended minerals but low chlorophyll concentrations, high cover of floating and submerged vegetation and dominance of eurytopic fish; (2) large, relatively deep lakes with moderately long residence time, high Potamogeton-cover that collapses during summer, and dominated by eurytopic fish; (3) smaller, isolated lakes at the longest distance from the river, Aquatic vegetation showed a clear seasonality related to the interaction between plant development and light conditions. Seasonal changes in fish distribution within the system merely followed the vegetation trends in different lakes and the conditions in the river channels. Past trends in the trophic gradient are discussed in the context of hydromorphological modifications in the Delta. There is a high potential for restoring natural processes owing to the high connectivity and large scale of the system., There are over 300 lakes interconnected by riverbranches and man-made canals in the Danube Delta (Romania). A multidisciplinary survey of these riverine lakes situated in large wetland complexes was made comprising hydrological modelling, remote sensing and monitoring of water quality, plankton, aquatic vegetation and fish communities. Between-lake differences in water quality and aquatic vegetation cover were inferred from satellite image. Based on channel and lake dimensions, hydrological characteristics of the lakes in the delta were determined: hydrological distance from a riverbranch, residence time and impact of reed water. Water-quality and biotic parameters (phyto- and zooplankton, submerged plants and fish) were sampled in a comparative survey in June 1997-1999 in subsets of the lakes. In a follow-up study in 2001-2002, seasonality of aquatic vegetation and fish were recorded. A clear distinction was found in three lake types: (1) inflow lakes at short distance to the river, with a high flushing rate, high load of suspended minerals but low chlorophyll concentrations, high cover of floating and submerged vegetation and dominance of eurytopic fish; (2) large, relatively deep lakes with moderately long residence time, high Potamogeton-cover that collapses during summer, and dominated by eurytopic fish; (3) smaller, isolated lakes at the longest distance from the river, Aquatic vegetation showed a clear seasonality related to the interaction between plant development and light conditions. Seasonal changes in fish distribution within the system merely followed the vegetation trends in different lakes and the conditions in the river channels. Past trends in the trophic gradient are discussed in the context of hydromorphological modifications in the Delta. There is a high potential for restoring natural processes owing to the high connectivity and large scale of the system.

Aquatic macrophytes are one of the biological quality elements in the Water Framework Directive (WFD) for which status assessments must be defined. We tested two methods to classify macrophyte species and their response to eutrophication pressure: one based on percentiles of occurrence along a phosphorous gradient and another based on trophic ranking of species using Canonical Correspondence Analyses in the ranking procedure. The methods were tested at Europe-wide, regional and national scale as well as by alkalinity category, using 1,147 lakes from 12 European states. The grouping of species as sensitive, tolerant or indifferent to eutrophication was evaluated for some taxa, such as the sensitive Chara spp. and the large isoetids, by analysing the (non-linear) response curve along a phosphorous gradient. These thresholds revealed in these response curves can be used to set boundaries among different ecological status classes. In total 48 taxa out of 114 taxa were classified identically regardless of dataset or classification method. These taxa can be considered the most consistent and reliable indicators of sensitivity or tolerance to eutrophication at European scale. Although the general response of well known indicator species seems to hold, there are many species that were evaluated differently according to the database selection and classification methods. This hampers a Europe-wide comparison of classified species lists as used for the status assessment within the WFD implementation process., Aquatic macrophytes are one of the biological quality elements in the Water Framework Directive (WFD) for which status assessments must be defined. We tested two methods to classify macrophyte species and their response to eutrophication pressure: one based on percentiles of occurrence along a phosphorous gradient and another based on trophic ranking of species using Canonical Correspondence Analyses in the ranking procedure. The methods were tested at Europe-wide, regional and national scale as well as by alkalinity category, using 1,147 lakes from 12 European states. The grouping of species as sensitive, tolerant or indifferent to eutrophication was evaluated for some taxa, such as the sensitive Chara spp. and the large isoetids, by analysing the (non-linear) response curve along a phosphorous gradient. These thresholds revealed in these response curves can be used to set boundaries among different ecological status classes. In total 48 taxa out of 114 taxa were classified identically regardless of dataset or classification method. These taxa can be considered the most consistent and reliable indicators of sensitivity or tolerance to eutrophication at European scale. Although the general response of well known indicator species seems to hold, there are many species that were evaluated differently according to the database selection and classification methods. This hampers a Europe-wide comparison of classified species lists as used for the status assessment within the WFD implementation process.

Defining the overall ecological status of lakes according to the Water Framework Directive (WFD) is to be partially based on the species composition of the aquatic macrophyte community. We tested three assessment methods to define the ecological status of the macrophyte community in response to a eutrophication pressure as reflected by total phosphorus concentrations in lake water. An absolute species richness, a trophic index (TI) and a lake trophic ranking (LTR) method were tested at Europe-wide, regional and national scales as well as by alkalinity category, using data from 1,147 lakes from 12 European states. Total phosphorus data were used to represent the trophic status of individual samples and were plotted against the calculated TI and LTR values. Additionally, the LTR method was tested in some individual lakes with a relatively long time series of monitoring data. The TI correlated well with total P in the Northern European lake types, whereas the relationship in the Central European lake types was less clear. The relationship between total P and light extinction is often very good in the Northern European lake types compared to the Central European lake types. This can be one of the reasons for a better agreement between the indices and eutrophication pressure in the Northern European lake types. The response of individual lakes to changes in the abiotic environment was sometimes represented incorrectly by the indices used, which is a cause of concern for the use of single indices in status assessments in practice., Defining the overall ecological status of lakes according to the Water Framework Directive (WFD) is to be partially based on the species composition of the aquatic macrophyte community. We tested three assessment methods to define the ecological status of the macrophyte community in response to a eutrophication pressure as reflected by total phosphorus concentrations in lake water. An absolute species richness, a trophic index (TI) and a lake trophic ranking (LTR) method were tested at Europe-wide, regional and national scales as well as by alkalinity category, using data from 1,147 lakes from 12 European states. Total phosphorus data were used to represent the trophic status of individual samples and were plotted against the calculated TI and LTR values. Additionally, the LTR method was tested in some individual lakes with a relatively long time series of monitoring data. The TI correlated well with total P in the Northern European lake types, whereas the relationship in the Central European lake types was less clear. The relationship between total P and light extinction is often very good in the Northern European lake types compared to the Central European lake types. This can be one of the reasons for a better agreement between the indices and eutrophication pressure in the Northern European lake types. The response of individual lakes to changes in the abiotic environment was sometimes represented incorrectly by the indices used, which is a cause of concern for the use of single indices in status assessments in practice.

This paper presents data showing phenotypic differences of Phragmites australis (Cav.) Trin. ex Steud. (Common reed) growing in Comana lake and in the Danube Delta (Romania). In Comana lake, tetra- and octoploids were found, whereas in the Danube Delta also hexaploids occurred. In freshwater habitats, shoots of octoploids were longer and thicker with more nodes than those of tetraploids. Panicles of octopoids were also larger than those of tetraploids. The number of alive leaves did not differ between ploidy levels. Total leaf area, however was higher of octo- than of tetraploids, which indicates that octoploids produced larger leaves. Octoploids also had thicker rhizomes. No differences in allocation of dry matter to leaves, stems, and leaves (blades and sheaths) were found between tetra- and octoploids. Both tetra- and octoploids shoots were among the tallest in the central Danube Delta. Tetraploids were morphologically more diverse in Comana lake than in the central Danube Delta. Within areas, size of shoots could, however, not be related to water depth. Salinity reduced shoot size of tetraploids considerably. Under saline conditions, no differences in morphology of shoots were found between tetra- and hexaploids. ([KEYWORDS: Danube Delta; water depth; salinity;environmental stress; plant morphology; Phragmites australis], This paper presents data showing phenotypic differences of Phragmites australis (Cav.) Trin. ex Steud. (Common reed) growing in Comana lake and in the Danube Delta (Romania). In Comana lake, tetra- and octoploids were found, whereas in the Danube Delta also hexaploids occurred. In freshwater habitats, shoots of octoploids were longer and thicker with more nodes than those of tetraploids. Panicles of octopoids were also larger than those of tetraploids. The number of alive leaves did not differ between ploidy levels. Total leaf area, however was higher of octo- than of tetraploids, which indicates that octoploids produced larger leaves. Octoploids also had thicker rhizomes. No differences in allocation of dry matter to leaves, stems, and leaves (blades and sheaths) were found between tetra- and octoploids. Both tetra- and octoploids shoots were among the tallest in the central Danube Delta. Tetraploids were morphologically more diverse in Comana lake than in the central Danube Delta. Within areas, size of shoots could, however, not be related to water depth. Salinity reduced shoot size of tetraploids considerably. Under saline conditions, no differences in morphology of shoots were found between tetra- and hexaploids. ([KEYWORDS: Danube Delta; water depth; salinity;environmental stress; plant morphology; Phragmites australis]