Lake Tegel is an extreme case of restoration: inflow treatment reduced its main external phosphorus (TP) load 40-fold, sharply focused in time, and low-P water flushed the lake volume ≈ 4 times per year. We analysed 35 years of data for the time TP concentrations took to decline from ≈ 700 to 20–30 µg/l, biota to respond and cyanobacteria to become negligible. The internal load proved of minor relevance. After 10 years, TP rea...

Summary The impact of environmental stimuli on the production of the widespread cyanobacterial hepatotoxin microcystin ( MC ) is under debate. Whereas transcriptional studies of the biosynthetic genes suggest a clear influence of light conditions on toxin production the data for the metabolite itself are inconsistent and highly strain‐specific. Here, we have reassessed the MC content by using two immunological detection techni...

Summary To investigate the abundance of active and inactive microcystin genotypes in populations of the filamentous cyanobacterium Planktothrix spp., individual filaments were grown as clonal strains in the laboratory and analysed for microcystin synthetase ( mcy ) genes and microcystin. Twenty‐three green‐pigmented strains of P. agardhii originating mostly from shallow water bodies fell into two groups, those possessing mcyA...