Cyanobacterial Water Blooms Seriously Change the Structure and Biodiversity of Phytoplankton Assemblages

Abstract

Pollution of surface waters by nutrients cause serious problems connected with mass development of planctonic cyanobacteria forming water blooms. Cyanobacteria produce a broad spectrum of toxic substances. In our study we tested the influence of cyanobacteria on species composition and abundance of phytoplancton. We used data from two reservoir near the city of Brno, Czech Republic. We found, that during the dominance of cyanobacterial species forming water blooms there is serious reduction on species diversity. Especially diatoms seem to be the most sensitive group of phytoplankton. Diatoms practically disappeared in samples, where cyanobacteria have formed blooms. Several statistical methods like principal component analysis and cluster analysis were applied to analyse biotic interaction and separate samples, where cyanobacteria could be responsible for reduction of phytoplankton diversity. Possible mechanisms of this phenomena should be connected with cyanotoxins produced by water blooms.