Intercalibration of the national classifications of ecological status for Eastern Continental lakes: Biological Quality Element: Phytoplankton

The European Water Framework Directive (WFD) requires the national classifications of good ecological status to be harmonised through an intercalibration exercise. In this exercise, significant differences in status classification among Member States are harmonized by comparing and, if necessary, adjusting the good status boundaries of the national assessment methods. Intercalibration is performed for rivers, lakes, coastal and transitional waters, focusing on selected types of water bodies (intercalibration types), anthropogenic pressures and Biological Quality Elements. Intercalibration exercises were carried out in Geographical Intercalibration Groups - larger geographical units including Member States with similar water body types - and followed the procedure described in the WFD Common Implementation Strategy Guidance document on the intercalibration process (European Commission, 2011). The Technical reports are organized in volumes according to the water category (rivers, lakes, coastal and transitional waters), Biological Quality Element and Geographical Intercalibration group. This volume addresses the intercalibration of the Eastern Continental Lake GIG Phytoplankton ecological assessment methods. Three countries (Bulgaria, Hungary, Romania) participated in the intercalibration exercise and harmonised their phytoplankton assessment systems. The results were approved by the WG ECOSTAT and included in the EC Decision on intercalibration (European Commission, 2018).JRC.D.2-Water and Marine Resource

Patterns of major photosynthetic pigments in freshwater algae. 1. Cyanoprokaryota, Rhodophyta and Cryptophyta

This study investigated major pigment patterns of 8 cyanoprokaryota, 2 rhodophytes and 2 cryptomonads isolated from freshwater ecosystems. Analysis was done by means of HPLC. The method, historically adapted to marine phytoplankton, was modified to accommodate limnic algae. Quantitative results obtained in this study can be used for phytoplankton quantification techniques based on pigment patterns. Compared to marine strains, the studied freshwater cyanoprokaryote strains reveal a more complex pigment pattern, including myxoxanthophyll, canthaxanthin and echinenone. Cryptophyta possess the two acetylenic class-specific marker compounds allo- and monadoxanthin, crocoxanthin was not detectable. Rhodophytes show a simple pigment pattern similar to marine species. Previous reports as to the existence of chlorophyll-d could not be confirmed (historical reports probably refer to an artefact of preparation). Besides methodological considerations, the phenomenon of complementary chromatic adaptation is discussed briefly

Patterns of major photosynthetic pigments in freshwater algae. 2. Dinophyta, Euglenophyta, Chlorophyceae and Charales

Major pigment patterns of 18 chlorophyceae, 7 charales, 4 euglenophyta, and 2 dinophyta isolated from freshwater ecosystems, were investigated by means of HPLC. In this study, quantitative results are presented, too, which are capable for phytoplankton quantification techniques based on pigment patterns. Chlorophyceae revealed a pattern similar to that of higher plants, but in some strains, loroxanthin as well as α-carotene were present. In charophytes, except for vegetative specimens of Chara tomentosa, γ-carotene was detected in antheridia only. Among investigated freshwater euglenophytes diadinoxanthin was the major carotenoid, with neoxanthin and ß-carotene present in minor amounts. Besides chlorophylls-a and -c, dinophytes contained high quantities of peridinin, whereas fucoxanthin was absent. An unknown component eluting just before violaxanthin showed a spectrum reminding of peridinin

Winter conditions in six European shallow lakes: a comparative synopsis

This review summarizes winter conditions from six polymictic European shallow lakes. The lakes range from oligotrophic to hyper-eutrophic. Four of the lakes freeze regularly while ice cover is absent or rare in the two others. Ice duration and timing of ice-out are significantly influenced by climate signals in three of the lakes. Winter water temperature remains higher in non-ice-covered lakes. No long-term trend in temperature is detectable except for one lake where winter water temperature began to increase in 1986. Secchi depth in winter is equal or greater than summer values in all six lakes indicating relatively better light conditions in winter. Total phosphorus concentration in winter ranges from 10 to 130 µg L–1, which is equal or lower than summer values and is unrelated to chlorophyll a in five of the sites. Phytoplankton species composition during winter differs largely at the six sites. The winter assemblages largely depend on the trophic level and the conditions during the previous season. Winter chlorophyll a and phytoplankton biomass are usually lower than summer values because of reduced photosynthetic rates. Bacterial production often exceeds primary production. Epipelic algal assemblages tend to proliferate during winter in both ice-covered and non-ice-covered lakes. Primary production is low during winter because of insufficient light. Zooplankton abundances and biomass critically depend on conditions during the previous season and the winter situation and are quite variable from year to year, but their values correlate with the trophic status of the lakes. As a result, winter conditions are important to understand seasonal and annual changes in shallow lakes