The combined effect of different temperatures and diurnal light intensity can be an effective tool for cyanobacterial bloom management considering hydrogen peroxide as an indicator

Abstract

Abstract Diurnal variations in oxidative stress conditions of cyanobacteria using laboratory experiments were conducted for assessing photoinhibition effects. The sufficient Microcystis aeruginosa cells were made in three sets at 30°C, 20°C, and 10°C for 23 days. The diurnal light changing exposure was performed after 23 days starting at 6:00 and continuing till 21:00. The samples were collected at three hour intervals — 6:00, 9:00, 12:00, 15:00, 18:00, and 21:00 — to analyze hydrogen peroxide (H2O2) concentration, protein concentration, chlorophyll-a (Chl-a) content, and catalase (CAT) activity. The production of H2O2 increased following the PAR intensity variation, with a delay of a few hours (peaking at15:00) in the different temperatures. The Chl-a content and protein concentration also declined as an effect of temperatures and the diurnal light intensities. CAT activity was proportionate to the H2O2/protein. No H2O2 concentrations detected outside cells indicated the biological production of H2O2 which was parameterized with H2O2/protein. The combined effect of different temperatures and diurnal light intensity shows that a decreasing trend of H2O2/protein is observed at 10°C compared with 30°C and 20°C. Hence, this combined effect of temperature and diurnal light change will be effective in cyanobacterial bloom treatment using H2O2 as an indicator.