The invasion and spread of non-native species of many different kinds of organisms is of increasing interest to researchers. Invasions by microscopic organisms, however, are poorly understood, and their impact on the environment is probably underestimated. We collected available data on nonnative and invasive/expansive algae and cyanobacteria in the Czech Republic; we mapped their distribution and assessed their impact on local species and other real or potential risks resulting from their spread. The list of alien species in the Czech Republic contains 10 species of cyanobacteria, 9 species of Bacillariophyceae, 1 species of Dinophyta, 1 species of Ulvophyceae, 2 species of Chlorophyceae, and 1 species complex of Zygnematopyceae. The literature on the worldwide occurrence of these taxa is also reviewed.

A submersible in situ spectrofluorometer, which permits the differentiation of four algal groups (green algae, diatoms, cryptophytes and cyanobacteria), was used for phytoplankton monitoring in five reservoirs with varying levels of eutrophication and composition of their phytoplankton communities. Data obtained in situ were compared to standard laboratory methods for phytoplankton quantification; concentration of chlorophyll a and microscopy analysis. A high correlation (r = 0.95, n = 96) between chlorophyll a levels using different methods was found in all types of phytoplankton community. Taxonomic analyses and cell counts were closely related to the ratio of algal classes measured by the in situ spectrofluorometer. The submersible device used in the study measures in a continuous mode, which is advantageous in comparison with discrete sampling. This method appears to be a good tool for water quality management and can be used in the detection of natural horizontal and vertical variability in phytoplankton communities or for the early detection of cyanobacterial blooms. The device used in this study is recommended as a screening tool that enables more effective sampling that can be focused on the localities and depths where changes in phytoplankton composition occur.Abbreviations: Chl a -chlorophyll a; FP -FluoroProbe; LED -light emitting diode

The aim of the presented paper was to evaluate the effect of cyanobacterial water blooms common in eutrophic reservoirs on blood indices of carp. A total of 180 individuals of juvenile carp (Cyprinus carpio L.) of the average body mass 36.9 g (1996) and 26.3 g (1997) were used in the experiments. The experimental fish were exposed to 4 different natural populations of cyanobacterial water blooms.In 1996, the populations of filamentous cyanobacteria (WB I) formed by Anabaena flos-aquae (90 %) and Aphanizomenon flos-aquae (10 %) at a concentration of 5.6 × 10 4 -3.2 × 10 5 cells . ml -1 without the presence of microcystins and colonial cyanobacteria Microcystis ichthyoblabe (80 %) with subdominant Microcystis aeruginosa (20 %) (WB II) at a concentration of 2.6 × 10 5 -3.6 × 10 6 cells⋅ml -1 with detected Microcystin LR (17.2 µg . g -1 of dry mass) were used. Exposure time was 168 h for filamentous species and 96 h for colonial species. In 1997 the monospecies population of filamentous cyanobacteria Anabaena flos-aquae (WB III) at a concentration of 5.3 × 10 4 -7.9 × 10 4 cells . ml -1 containing two different microcystins (total concentration 56.06 µg . g -1 of dry mass) and water bloom (WB IV) formed by colonial species Microcystis ichthyoblabe (40 %) and Microcystis aeruginosa (30 %) with filamentous Anabaena flos-aquae (30 %) at a concentration of 1.8 × 10 6 -1.4 × 10 7 cells . ml -1 which contained three microcystins (total concentration 289.3 µg . g -1 of dry mass) were used. Both populations were exposed for 48 h. Control fish in both tests were kept in treated drinking water infused 24 h before the start of the experiment.Haematological examination showed significant changes (p < 0.05) in leukocrit (BC) of fish exposed to the cyanobacterial population WB I, and in haematocrit (PCV) values, total protein concentration (TP), ALT and AST activities in fish exposed to the population WB II as compared to control fish. LDH activity in blood plasma of carp exposed to cyanobacterial population WB II was increased (p < 0.01) as compared to control fish. TP values from cyanobacterial populations WB III a WB IV were significantly reduced (p < 0.05) and values of ALT activities increased (p < 0.01). Moreover, significant increase (p < 0.05) of AST activity was recorded for fish exposed to cyanobacterial water bloom WB III.The observations confirmed adverse effects of cyanobacterial biomass on juvenile carp. The effect of toxic water bloom populations was manifested by changes of blood plasma indices. Toxins supply here water the role of catalyzers enhancing the negative influence of toxic high ammonia values. Carp, cyanotoxins, water blooms, plasma enzymesCyanobacteria as photosynthesizing organisms produce biologically active compounds that may affect growth and development of other water organisms and physical and chemical characteristics of water ( M ar‰álek and Turánek 1996). Great attention has recently been paid to the impact of cyanobacterial toxins on fish. Clinical symptoms of poisoning, pathological changes ...

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Phytoplankton communities of three water bodies in the Lednice park were studied from 22nd April till 1st October 2002. These water bodies are the Zámecký pond, Růžový pond and the Dyje River, which is water source of both ponds.Phytoplankton samples were taken every two weeks between 8 - 9 am. Collected phytoplankton samples were preserved with 4% formalin solution and Lugol solution (JJK) and transported to the laboratory. They were determined and counted using inverted microscope. Water temperature, pH and dissolved oxygen were measured in the field using digital portable instruments. Total of 317 phytoplankton species were determined in this study.Heavy algal bloom was observed in the Zámecký pond in mid-summer coinciding with increase in water temperature. Fish diseases and partial mortality occurred during the period of algal bloom and unpleasant smell was dominant feature. A light algal bloom was also observed in the Růžový pond and the Dyje River nearly by the end of summer.The main algae species responsible for blue-green algae bloom were Anabaena flos-aquae, Microcystis aeruginosa, M. ichtyoblabe, M. flos-aquae and M. wesenbergii. Dissolved oxygen values varied between 3.4 - 19.5 mg l-1, pH ranged from 7.6 - 9.7. Secchi depth varied from 0- 65 cm in the Zámecký pond, 15-45 cm in the Růžový pond and 35-65 cm in the Dyje River. Concentration of total phosphate, nitrate and chlorophyll-a in the Dyje River before drainage into the Zámecký and Růžový pond verified heavy nutrient load (Total-P = 0.3, NO3- = 12 mg.l-1) of the river. Although the Dyje River is main water source for both ponds, presence of relatively different phytoplankton communities in these two ponds suggest that probably different nutrient sources might be responsible for differences in phytoplankton communities and eutrophication patterns in the Zámecký pond as compared to the Růžový pond.