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The present work to study the composition and diversity of phytobenthic communities was conducted at downstream to a 330 MW hydroelectric dam, constructed on River Alaknanda, Uttarakhand. In the present study, a total of 48 genera of phytobenthos belonging to 23 families of 9 orders and 5 classes were recorded. The Chlorophyceae and Bacillariophyceae were the most dominant class respectively. Among the genus, Gomphonema and Navicula were the predominant genera that suggest the organic pollution at downstream to dam. Habitat heterogeneity reflects the increased density, diversity and richness of the phytobenthic communities downstream to dam. [ABSTRACT FROM AUTHOR]

To test if phytobenthic algae provide additional important information to macrophytes and phytoplankton for lake monitoring, we sampled two large lakes in Norway. In each lake, we analyzed water chemistry and phytoplankton above the deepest site, recorded macrophytes and non-diatom phytobenthic algae at 20 sites around the shoreline and estimated site-specific nutrient input from land cover. Since no ready-to-use phytobenthos index exists for lakes in Norway, we tested the PIT index developed for rivers, commonly perceived signs of disturbance such as high algal cover, and taxon richness as well as similarity patterns. Both lakes were nutrient poor, but had potential local nutrient inputs (villages, agriculture). In neither of the lakes did phytobenthos indicate a worse overall ecological status than macrophytes and phytoplankton. Our data therefore, did not suggest that it would be useful to add phytobenthos into surveillance monitoring of lakes in Norway. There was a loose correlation between macrophyte and phytobenthic site-specific taxon richness and similarities. This means that macrophytes and phytobenthos do indeed give partly redundant information. High algal cover was found at sites with both high and low phosphorus input. Using algal cover as indicator of site-specific nutrient input is therefore overly simplistic. Urban and cultivated areas were associated with a more eutrophic PIT. This indicates that the PIT, despite being developed for lotic waters, may be used to detect site specific nutrient input in lakes. [ABSTRACT FROM AUTHOR]

Abstract: The reduction and equalization of the salt concentrations in the River Werra have resulted in a gradual recovery of the aquatic flora. Spatial high-resolution macrophyte mappings document the spread of the aquatic vascular plants in the middle and lower River Werra. Simultaneously, the plankton blooms have declined. Changes in the composition of the algal communities including diatoms also indicated lower salinity. In addition to the salinity, high nutrient concentrations, waste water discharges and structural degradation are important stressors in the River Werra as shown by e.g. low species richness of vascular plants and the common occurrence of pollution tolerant diatoms. From the existing data it is clear that an encompassing improvement of the ecological conditions in the River Werra can only be achieved by further restoration measures considering all stressors. [Copyright &y& Elsevier]

Abstract: Spatial patterns on a very small scale (10cm), and the effect of artificial barriers on the composition of phytobenthic algal assemblages along two transects within different microhabitat types were investigated. Samples were taken in a peat bog along linear transects on a scale of 10cm, and water chemistry was examined. The distribution of algae along both transects was influenced by both spatial distance and environmental conditions in similar proportions. Differences in species composition in various parts of the transects were observed, but this pattern was primarily related to the abundance of species, rather than to their presence/absence in samples. Similarity in species composition correlated with spatial distance and environmental parameters in both microhabitat types. I concluded that, given a homogenous environment on a small scale, spatial distribution of algae is affected by both the environmental conditions of the microhabitats and their dispersal limitations. Moreover, an artificial barrier constituted an obstruction for water and nutrient flow, as well as algal migration, and had an impact on species composition. [Copyright &y& Elsevier]

Abstract: The eukaryotic community of the Río Tinto (SW, Spain) was surveyed in fall, winter and spring through the combined use of traditional microscopy and molecular approaches, including Denaturing Gradient Gel Electrophoresis (DGGE) and sequence analysis of 18S rRNA gene fragments. Eukaryotic assemblages of surface sediment biofilms collected in January, May and September 2002 were compared from 13 sampling stations along the river. Physicochemical data revealed extremely acidic conditions (the pH ranged from 0.9 to 2.5) with high concentrations of heavy metals, including up to 20mgl−1 Fe, 317mgl−1 Zn, 47mgl−1 As, 42mgl−1 Cd and 4mgl−1 Ni. In total, 20 taxa were identified, including members of the Bacillariophyta, Chlorophyta and Euglenophyta phyla as well as ciliates, cercomonads, amoebae, stramenopiles, fungi, heliozoans and rotifers. In general, total cell abundances were highest in fall and spring but decreased drastically in winter, and the sampling stations with the most extreme conditions showed the lowest number of cells, as well as the lowest diversity. Species diversity did not vary much during the year. Only the filamentous algae showed a dramatic seasonal change, since they almost disappeared in winter and reached the highest biomass during the summer. Principal Components Analysis (PCA) showed a high inverse correlation between pH and most of the heavy metals analyzed, as well as Dunaliella sp., while Chlamydomonas sp. was directly related to pH during May and September. Three heavy metals (Zn, Cu and Ni) remained separate from the rest and showed an inverse correlation with most of the species analyzed, except for Dunaliella sp. [Copyright &y& Elsevier]

Abstract: A new assessment system for macrophytes and phytobenthos in German lakes according to the Water Framework Directive of the European Community is described. Based on biological, chemical and hydromorphological data from about 100 lake sites covering the main ecoregions, hydromorphological lake types and degradation forms, biocoenotic types could be defined. For developing a classification system the quality element macrophytes and phytobenthos was divided into two components: macrophytes and benthic diatoms. For macrophytes 4 and for benthic diatoms 4 lake types were identified. The benthic vegetation at reference conditions is described and degradation is characterised as deviation in benthic vegetation species composition and abundance from the reference biocoenosis. For classification in five ecological status classes, several metrics were developed and used in combination with existing indices. For a few of the described lake types further investigations are necessary before a classification can be developed. [Copyright &y& Elsevier]

Abstract: A new assessment system for macrophytes and phytobenthos in German rivers meeting the requirements of the Water Framework Directive (WFD) of the European Community is described. Biocoenotic types based on biological, chemical and hydromorphological data from over 200 river sites covering the main ecoregions, hydromorphological stream types and degradation forms have been defined. For developing a classification system the quality element macrophytes and phytobenthos was divided into three components: macrophytes, benthic diatoms and remaining phytobenthos. For macrophytes seven types including one subtype, for benthic diatoms 14 types including three subtypes and for the remaining phytobenthos five river types were identified. The benthic vegetation at reference condition was described for most of the river types. Degradation is characterised as deviation in benthic vegetation species composition and abundance from the reference biocoenosis. For classification in five ecological status classes, several metrics were developed and used in combination with existing indices. For some of the described river types additional investigations are necessary before a classification system can be developed. [Copyright &y& Elsevier]

A general list of algae for benthos of the northwestern shelf of the Black Sea was represented. It contains 186 species (Chlorophyta -- 62, Phaeophyta -- 41, Rhodophyta -- 81, and Xanthophyta -- 2). Phytogeographycal and ecological characteristics are given for each species and for rare species, additionally, the category of danger. Nine species (Chlorophyta -- 3, Rhodophyta -- 5, Xanthophyta -- 1) are first cited for this area. [ABSTRACT FROM AUTHOR]

• Phytobenthos in lowland lakes in Romania does not demonstrate a strong response to phosphorus. • Assemblage composition is, instead, determined by biochemical oxygen demand and conductivity. • A new metric to evaluate ecological status using phytobenthos in these lakes is described. • Expected values of this metric are derived from a quantile regression of the index against conductivity. • As conductivity is susceptible to climate change, 2010 values are used as benchmarks when calculating expected index values. In contrast to diatom assemblages in lakes in most other parts of Europe, those in lowland lakes in Romania appear to be determined primarily by biochemical oxygen demand (BOD) and conductivity rather than by nutrients. This has confounded the development of a Water Framework Directive-compatible phytobenthos assessment system for Romanian lakes and led, instead, to the development of a new metric, the Romanian Diatom Index (RDI), which captures these gradients. The primary anthropogenic stressor is assumed to be BOD whilst conductivity is a product of background geology and climate. The RDI is strongly correlated with BOD, and ecological quality ratios (EQRs) are computed by dividing the observed RDI by an expected value, determined from the 90th percentile of the relationship between RDI and conductivity. This equates to the "best available" RDI at any point on the conductivity gradient and, in the absence of true "reference sites", has been assumed to represent the boundary between high and good status. The boundary between good and moderate status has been set at the point where the sum of valves of taxa tolerant to elevated BOD exceeds the sum of valves of taxa that are sensitive to elevated BOD. The position of this boundary has been further validated by the use of a Threshold Indicator Species Analysis (TITAN). In view of the susceptibility of conductivity to climate warming, 2010 values of conductivity have been used to ensure a stable benchmark against which future changes can be measured. This study highlights the challenges involved in performing reliable ecological assessments in situations that are, by the standards of much of Europe, atypical. [ABSTRACT FROM AUTHOR]