Characterizing vertical migration of Microcystis aeruginosa and conditions for algal bloom development based on a light-driven migration model
- 144 Downloads
Light-driven vertical migration is critical in dense aggregation of Microcystis aeruginosa during algal blooms under reduced turbulence conditions in natural water bodies. This study examined the vertical migration characteristics of Microcystis aeruginosa in calm water based on a colony migration model with consideration of cell density change, and demonstrated the effects of mucilage fraction, colony size, irradiance intensity, and water turbidity. The results suggest that colonies with larger radii and under higher irradiance usually had a larger daily averaged retention time at the water surface (DRT). In addition to colony size, mucilage was found to be important in changing the vertical migration behavior of Microcystis colonies, in which increasing mucilage volume fraction can increase the migrating velocity of the colony as well as the length of time it remains at the water surface. Increase of light extinction also favors the aggregation of colonies at the surface. An approximate critical value of 2400 µmol photons m2 s−1 for maximum irradiance was found for persistent algal bloom development under the given simulation conditions. Extremely small colonies exposed to irradiance below the critical value were not likely to migrate to the water surface to form algal blooms. According to the DRT values, three regions with different ranges of irradiance and colony size were proposed as the critical conditions for algal bloom development. Rough comparisons to field observations suggested that these results were reasonable and meaningful, and have the potential to be applied in real cases following further validation by more detailed investigations.
KeywordsVertical migration Daily-averaged retention time Colony radius Irradiance Mucilage
This work was financially supported by the Special Foundation (Class D) of the “Hundred Talents Program” of the Chinese Academy of Sciences (CAS), and by the National Natural Science Foundation of China (11202217).
- Hunter PD, Tyler AN, Willby NJ, Gilvear DJ (2008) The spatial dynamics of vertical migration by Microcystis aeruginosa in a eutrophic shallow lake: a case study using high spatial resolution time-series airborne remote sensing. Limnol Oceanogr 53:2391–2406. doi: 10.4319/lo.2008.53.6.2391 CrossRefGoogle Scholar
- Hutchinson GE (1967) A treatise on limnology. Introduction to lake biology and the limnoplankton, vol 2. Wiley, New YorkGoogle Scholar
- Oliver RL, Ganf GG (2002) Fresh water blooms. In: Whitton BA, Potts M (eds) The ecology of cyanobacteria—their diversity in time and space. Kluwer Academic, Dordrecht, pp 149–194Google Scholar
- Walsby AE, Reynolds CS (1980) Sinking and floating. In: Morris I (ed) The physiological ecology of phytoplankton. Blackwell Scientific Publications, Oxford, pp 371–412Google Scholar