Research Article

Effects of mixing intensity on colony size and growth of Microcystis aeruginosa

¹ Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, PR China
² School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, PR China
³ Department of Microbiology, The University of Tennessee, Knoxville, TN 37996, USA

^* Corresponding author: yanggj1979@163.com

Received: 19 February 2019
Accepted: 5 May 2019

Abstract

Mixing is an integral environmental factor that affects lake ecosystems. For the cyanobacterium Microcystis, colony size is important with respects to migration velocity, how cells respond to grazing pressure, light attenuation, nutrient uptake and growth. To understand how mixing shapes colony size and the growth of Microcystis, we measured the effects of different current velocities (0, 0.16, 0.32, 0.64, and 1.28 m s⁻¹) on M. aeruginosa in Lake Taihu. After 24 h of continuous mixing, the mean colony sizes of M. aeruginosa in the controls, 0.16, 0.32, 0.64, and 1.28 m s⁻¹ groups were 23.6, 50.1, 92.9, 67.8, and 37.3 μm, respectively. Colony sizes of M. aeruginosa in all treatment groups were significantly larger than those in controls. As well, the concentration of soluble extracellular polysaccharide and bound extracellular polysaccharides of M. aeruginosa in all treatment groups were significantly higher than those in controls. Except for the highest level of mixing (1.28 m s⁻¹), the growth rate of M. aeruginosa was significantly higher than that in controls. This study suggested that mixing intensity over short time periods can significantly influence colony size and the growth of M. aeruginosa.