Effect of light-mediated variations of colony morphology on the buoyancy regulation of Microcystis colonies. (15th May 2023)

• Record Type: Journal Article
• Authors: Xu, Gang; Zhang, Yanxue; Yang, Tiantian; Wu, Huaming; Lorke, Andreas; Pan, Min; Xiao, Bangding; Wu, Xingqiang
• Is Part Of: Water research. Volume 235(2023)
• Publication Date: 2023-05-15
• Subjects: Light availability -- Microcystis colony -- Buoyancy -- Colony compactness -- Colony size; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2023.119839
• Languages: English
• ISSNs: 0043-1354

Abstract

Highlights: Low light intensity can promote the persistent floatation of microcystis colony. High light intensity can induce high growth rate and large size of colonies. Loose and large colonies can easy sink after a long term exposure to high light. Light attenuation inside colonies restricts the maximal colony size. Abstract: Light is an important driver of algal growth and for the formation of surface blooms. Long-term buoyancy maintenance of Microcystis colonies is crucial for their aggregation at the water surface and the following algal bloom development. However, the effect of light-mediated variations of colony morphology on the buoyancy regulation of Microcystis colonies remains unclear. In this study, growth parameters, colony morphology and floatation/sinking performance of Microcystis colonies were determined to explore how variations in colony morphology influence the buoyancy of colonies under different light conditions. We quantified colony compactness through the cell volume to colony volume ratio ( VR ) and found different responses of colony size and VR under different light intensities. Microcystis colonies with higher VR could stay longer at the water surface under low light conditions, which was beneficial for the long-term growth and buoyancy maintenance. However, increased colony size and decreased compactness were observed at a later growth stage under relatively higher light intensity (i.e., >108 µmol photons m −2 s −1 ). Interestingly, we found a counterintuitive negative correlation between colony size and buoyancy of Microcystis under high light intensity. Additionally, we found that the influence of colony morphology on buoyancy was stronger at high light intensity. These results indicate that light could regulate the buoyancy via colonial morphology and that the role of colony morphology in buoyancy regulation needs to be accounted for in further studies under variable environmental conditions. Graphical abstract: Image, graphical abstract