Effects of temperature and pH on the competition between diatom Nitzschia palea and cyanobacterium Microcystis aeruginosa

Abstract

 This study is investigated to the competition between cyanobacterium Microcystis aeruginosa and diatom Nitzschia palea that can increase their cell number in a favorable environment for the occurrence of water bloom. We particularly focused on the temperature and pH effects on the inhibition effects of M. aeruginosa by N. palea. The maximum cell yield of M. aeruginosa reduced by approximately 50 % in the co-culture with N. palea at 15–30 ℃ as compared to that in the monoculture. N. palea also reduced the maximum cell yield of M. aeruginosa by 33, 54 and 66 % at pH 7.0, 8.0 and 9.0, respectively. N. palea reduced M. aeruginosa growth in the culture condition where water bloom is likely to occur. However, M. aeruginosa remained the dominant species in co-culture at 20–30 ℃ or pH 7.0–8.0. It is necessary to artificially increase the relative abundance of N. palea for enhancing the inhibition effect of M. aeruginosa.