The purpose of the present research was to analyze the available data on river restoration projects in Europe. As the framework of our study, we conducted a structured international survey. We asked selected entities and experts from among those responsible for river restoration in European countries about the details and costs of European Union river restoration projects. We examined 119 river restoration projects that were implemented in Europe between 1989 and 2016; during the collection of data, some of the projects were still ongoing. Based upon the collected data we observed that the number of river restoration projects has been increasing since 1989, which expresses society’s growing interest in improving the quality of aquatic environments. We revealed that 56% of these European river restoration projects have been implemented by dedicated entities and stakeholders, not as part of any structured, larger-scale river restoration policy. This indicates that most European countries do not have integrated plans for river restoration. Our analysis showed that 52% of the projects analyzed have been designed and implemented without the participation of local stakeholders. It also showed that the budgets for river restoration projects did not differ significantly across various time horizons from 1989 to 2016. In our study, the average cost of restoring 1 ha of an European river was 310,000 euros (EUR). Considering these projects’ permanent assets and including their amortization, we calculated the average unit price of a river restoration’s value in terms of ecosystem meta-service to be 7757 EUR·ha⁻¹·year⁻¹.

The Macrophyte Index for Rivers (MIR) was developed in 2007, and it was one of the first biological methods developed in Poland under the requirements of the Water Framework Directive to assess the ecological status of running waters. It is based on the quantitative and qualitative evaluation of 153 indicator taxa. The aim of this study was to evaluate the ability of the MIR method to detect trophic degradation in rivers and to compare its efficiency with other macrophyte metrics. Our investigation was based on 100 sites, representing a very clear gradient from near oligotrophic to eutrophic conditions. The results showed that macrophytes can be distinguished in terms of their ecological requirements for nutrient concentration in water, and this can be used to develop an effective system of freshwater assessment. The MIR was shown to be the indicator most strongly correlated with various forms of nutrients, and it was demonstrated that calibration of the macrophyte method to local biogeographical conditions resulted in greater effectiveness of the assessment method.

The aim of the study was to identify the vegetation pattern in the different types of watercourses basing on survey in reference conditions in a wide geographical gradient, including mountain, upland and lowland rivers. We tested relationship between composition of macrophytes to environmental variables including: altitude, slope, catchment area, geology of valley, land use, hydromorphological features, water physical and chemical measurements. Analysis based on 109 pristine river sites located throughout major types of rivers in Central Europe. Qualitative and quantitative plant surveys were carried out between 2005 and 2013. Based on TWINSPAN classification and DCA analysis, six macrophyte types were distinguished. The lowland sites were divided into the following three types: humic rivers and two types of siliceous rivers depending on the catchment area, including medium-large and small rivers. The mountain and upland rivers were divided into three geological types: siliceous, calcareous and gravel. We found that the variation of macrophyte communities was determined by several habitat factors (mainly altitude, flow type, riverbed granulometry, conductivity and alkalinity), whereas the spatial factor was rather limited; further, the plant diversity was not reflected accurately by the European ecoregion approach.

The study was carried out from 2007 to 2010 in two ecoregions: the Carpathians and the Central Highlands. The objectives of our survey were to test the existing biological index metric based on benthic macroinvertebrates at reference conditions in the high- and mid-altitude mountain streams of two ecoregions according to the requirements of the EU WFD and to determine which environmental factors influence the distribution of benthic macroinvertebrates. Our results revealed statistically significant differences in the values of the physical and chemical parameters of water as well as the mean values of metrics between the types of streams at the sampling sites. RDA analysis showed that the temperature of the water, pH, conductivity, the stream gradient, values of the HQA index, and altitude were the parameters most associated with the distribution of benthic macroinvertebrate taxa and the values of the metrics. The values of biological indices should be considered according to the stream typology including altitude and geology. At the reference conditions, the suggested border values of biological indices are very harsh. The values of the biological indices of most sampling sites did not correspond to the requirements of the high status in rivers. The streams at altitudes above 1,200 m a.s.l. should be treated as another river type and new reference values should be established.

Freshwater classification according to the Water Framework Directive (WFD) is based on estimation of the deviation between biological elements found on river stretch in comparison with communities detected in the same river type under reference conditions (undisturbed and near-natural habitats). We present analyses to describe macrophyte development in pristine lowland rivers and to reveal the variation among various stream types. The study is based on a country-wide survey of Poland with a dataset of 642 sites on 367 water courses. Surveyed rivers covered the whole lowland area of Poland. Field surveys were conducted using the Polish macrophyte approach, which enabled calculation of several macrophyte metrics. Firstly, a numerical index MIR (Macrophyte Index for Rivers) was computed, which reflects river degradation, especially eutrophication. Furthermore, five diversity metrics were calculated. Each survey, in addition to macrophyte assessment, was supplemented by a complex suite of environmental records. Reference conditions were defined using four criteria: (1) catchment land use, (2) hydromorphological features, (3) water quality and (4) biological assessment. The selected reference lowland rivers included 40 sites. To classify plant data, two-way indicator species analysis Twinspan was used. This resulted in distinguishing four end-clusters which were heterogeneous according to plant composition: organic rivers and three types of siliceous rivers (small with sandy substrate, small with stony substrate and large rivers). The differentiation of environmental factors between river types was confirmed by a variance analysis (ANOVA). Furthermore, the environmental database was explored with principal component analysis (PCA). The PCA principal components were analysed against river types with the canonical correspondence analysis (CCA). Finally botanical differences between identified river types have been detected, using botanical metrics the share of different macrophyte groups and relationships with particular species were defined.