In 1995 and 1996 a total of 55 German water bodies with different trophic states were investigated for the presence of potentially microcystin-producing cyanobacteria.
The seston biomass of over 500 samples was analyzed by HPLC to assess microcystin content.
The highest microcystin content per dry weight was found when Planktothrix rubescens was dominant, followed by Planktothrix agardhii and Microcystis spp.
The microcystin to chlorophyll-a ratio mostly varied between 0.1 and 0.5, with maxima of 1-2.
In over 70% of the samples from pelagic water, particulate microcystin concentrations were below 10 mug L-1.
By contrast, spatial and temporal concentrations varied by 4 orders of magnitude (2-25,000 mug L-1) at bathing sites in 1997 during a mass development of Microcystis spp.
The seasonal peak of development of Microcystis spp. occurred from June to September and of Planktothrix agardhii from September to November.
Planktothrix rubescens, however, was almost perennial.
The seasonal levels of these cyanobacteria were clearly reflected by microcystin concentrations in the water bodies.
Mots-clés Pascal : Toxique, Niveau trophique, Variation saisonnière, Toxicité, Diversité espèces, Concentration chimique, Espèce dominante, Microcystis, Cyanobacteria, Bactérie, Nostoc, Anabaena, Allemagne, Europe, Milieu eau douce, Lac artificiel, Phytoplancton, Heptapeptide, Toxine, Planktothrix rubescens, Microcystine
Mots-clés Pascal anglais : Poison, Trophic level, Seasonal variation, Toxicity, Species diversity, Chemical concentration, Dominant species, Microcystis, Cyanobacteria, Bacteria, Nostoc, Anabaena, Germany, Europe, Freshwater environment, Artificial lake, Phytoplankton, Heptapeptide, Toxin
Notice produite par :
Inist-CNRS - Institut de l'Information Scientifique et Technique
Cote : 99-0327193
Code Inist : 002A05B10. Création : 16/11/1999.