design: Genomic DNA was isolated from biomass retained in glass fiber filters after water filtering from water reservoirs. For 16S rRNA (V3-V4 variable region), cyanobacterial specific primers CYA359F and CYA781Ra/Rb in the same reactrion. For cyanotoxin-biosynthesis: mcyE, primers HEPR/HEPF; anaF atxoaf/atxoar; sxtA sxtaf/sxtar.