In mid-July and August 2003 and 2004, 18 reservoirs in the Czech Republic were sampled for phytoplankton species composition and concentration of intracellular microcystins (MCs). As a consequence of high nutrient loading, most of the reservoirs experienced cyanobacterial blooms of various intensities, with the prevalence of cyanobacteria increasing markedly in August, along with a conspicuous shift in species composition toward dominance of Microcystis spp. Microcystins were detected in 90% of the samples, and their amount also increased considerably in August, reflecting the cyanobacterial biomass. In Microcystis-dominated samples, a significantly higher amount of MCs (p < 0.001) occurred than in samples in which other taxa prevailed. Microcystins were positively correlated with chlorophyll a and cyanobacterial biovolume (p < 0.05, R2 = 0.61 and 0.66, respectively), with the strongest correlation found for Microcystis spp. biovolume (p < 0.001, R2 = 0.87). This taxon was the most important producer of MCs in Czech reservoirs. The main structural variants of MCs were MC-LR, MC-RR, and MC-YR. This study's data also indicate that the relative share of MC variants (MC-LR and MC-RR) varies considerably with time, most likely as a consequence of different species and strain compositions during the summer. This study clearly demonstrates a high prevalence of MC-producing cyanobacteria in Czech reservoirs. Therefore, regular monitoring of these reservoirs is highly desirable in an effort to minimize potential health risks to the human population. Copyright 2006 Wiley Periodicals, Inc.

• MeSH
• biomasa MeSH
• cyklické peptidy metabolismus   MeSH
• eutrofizace MeSH
• mikrobiologie vody MeSH
• mikrocystiny MeSH
• monitorování životního prostředí MeSH
• populační dynamika MeSH
• roční období MeSH
• sinice růst a vývoj   MeSH
• sladká voda chemie   mikrobiologie   MeSH
• zásobování vodou MeSH
• Publikační typ
• práce podpořená grantem MeSH

• MeSH
• chemické znečištění vody škodlivé účinky   MeSH
• financování organizované MeSH
• fytoplankton patogenita   účinky léků   MeSH
• lidé MeSH
• škodlivý vodní květ účinky léků   MeSH
• sladká voda mikrobiologie   MeSH
• Check Tag
• lidé MeSH
• Geografické názvy
• Česká republika MeSH