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Wu H, Wu X, Yang T, Wang C, Tian C, Xiao B, Lorke A. Feedback regulation of surface scum formation and persistence by self-shading of Microcystis colonies: Numerical simulations and laboratory experiments. WATER RESEARCH 2021; 194:116908. [PMID: 33596491 DOI: 10.1016/j.watres.2021.116908] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2020] [Revised: 01/31/2021] [Accepted: 02/02/2021] [Indexed: 06/12/2023]
Abstract
Light availability is an important driver of algal growth and for the formation of surface blooms. The formation of Microcystis surface scum decreases the transparency of the water column and influences the vertical distribution of light intensity. Only few studies analysed the interactions between the dynamics of surface blooms and the light distribution in the water column. Particularly the effect of light attenuation caused by Microcystis colonies (self-shading) on the formation of surface scum has not been explored. In the present study, we simulate the effect of variable cell concentration of Microcystis colonies on the vertical distribution of light in the water column based on experimental estimates of the extinction coefficient of Microcystis colonies. The laboratory observations indicated that higher cell concentration of Microcystis enhance the light attenuation in water column and promotes surface scum formation. We extended an existing model for the light-driven migration of Microcystis by introducing the effect of self-shading and simulated the dynamics of vertical migration for different cell concentrations and different colonial morphologies. The simulation results show that high cell concentrations of Microcystis promote surface scum formation, as well as its persistence throughout diel photoperiods. Large and tight Microcystis colonies facilitate scum formation, while small and loose colonies increase scum stability and persistence. This study reveals a positive feedback regulation of Microcystis surface scum formation and stability by self-shading and provides novel insights into the underlying mechanisms.
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Affiliation(s)
- Huaming Wu
- Key Laboratory of Algal Biology of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xingqiang Wu
- Key Laboratory of Algal Biology of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
| | - Tiantian Yang
- Key Laboratory of Algal Biology of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Chunbo Wang
- Key Laboratory of Algal Biology of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Cuicui Tian
- Key Laboratory of Algal Biology of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Bangding Xiao
- Key Laboratory of Algal Biology of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Andreas Lorke
- Institute for Environmental Sciences, University of Koblenz-Landau, Landau 76829, Germany
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Xiao M, Hamilton DP, O'Brien KR, Adams MP, Willis A, Burford MA. Are laboratory growth rate experiments relevant to explaining bloom-forming cyanobacteria distributions at global scale? HARMFUL ALGAE 2020; 92:101732. [PMID: 32113600 DOI: 10.1016/j.hal.2019.101732] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 11/04/2019] [Accepted: 12/17/2019] [Indexed: 06/10/2023]
Abstract
Predicting algal population dynamics using models informed by experimental data has been used as a strategy to inform the management and control of harmful cyanobacterial blooms. We selected toxic bloom-forming species Microcystis spp. and Raphidiopsis raciborskii (basionym Cylindrospermopsis raciborskii) for further examination as they dominate in 78 % and 17 %, respectively, of freshwater cyanobacterial blooms (cyanoHABs) reported globally over the past 30 years. Field measurements of cyanoHABs are typically based on biomass accumulation, but laboratory experiments typically measure growth rates, which are an important variable in cyanoHAB models. Our objective was to determine the usefulness of laboratory studies of these cyanoHAB growth rates for simulating the species dominance at a global scale. We synthesized growth responses of M. aeruginosa and R. raciborskii from 20 and 16 culture studies, respectively, to predict growth rates as a function of two environmental variables, light and temperature. Predicted growth rates of R. raciborskii exceeded those of M. aeruginosa at temperatures ≳ 25 °C and light intensities ≳ 150 μmol photons m-2 s-1. Field observations of biomass accumulation, however, show that M. aeruginosa dominates over R. raciborskii, irrespective of climatic zones. The mismatch between biomass accumulation measured in the field, and what is predicted from growth rate measured in the laboratory, hinders effective use of culture studies to predict formation of cyanoHABs in the natural environment. The usefulness of growth rates measured may therefore be limited, and field experiments should instead be designed to examine key physiological attributes such as colony formation, buoyancy regulation and photoadaptation. Improving prediction of cyanoHABs in a changing climate requires a more effective integration of field and laboratory approaches, and an explicit consideration of strain-level variability.
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Affiliation(s)
- Man Xiao
- Australian Rivers Institute, Griffith University, Nathan, Australia; School of Environment and Science, Griffith University, Nathan, Australia.
| | - David P Hamilton
- Australian Rivers Institute, Griffith University, Nathan, Australia
| | - Katherine R O'Brien
- School of Chemical Engineering, University of Queensland, St Lucia, Australia
| | - Matthew P Adams
- School of Chemical Engineering, University of Queensland, St Lucia, Australia; School of Earth and Environmental Sciences, University of Queensland, St Lucia, Australia; School of Biological Sciences, University of Queensland, St Lucia, Australia
| | - Anusuya Willis
- Australian Rivers Institute, Griffith University, Nathan, Australia; Australian National Algae Culture Collection, CSIRO, Hobart, Tasmania, Australia
| | - Michele A Burford
- Australian Rivers Institute, Griffith University, Nathan, Australia; School of Environment and Science, Griffith University, Nathan, Australia
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Feng G, Zhu W, Hu S, Xue Z, Wang R, Chen H. Attenuation of light influences the size of Microcystis colonies. HARMFUL ALGAE 2019; 89:101667. [PMID: 31672232 DOI: 10.1016/j.hal.2019.101667] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 09/04/2019] [Accepted: 09/21/2019] [Indexed: 06/10/2023]
Abstract
Colony formation provides excellent advantages for the dominance of Microcystis. However, studies on microenvironments during the process of colony formation are rare, especially regarding intra-colony light usage. This study analyzed the attenuation of light intensity in Microcystis colonies, where most objects followed Lambert-Beer law ( [Formula: see text] ). Intra-colony light limited the maximum thickness of the colony (BMax=4.3×105c-1) and thus affected colony size. Field data showed that the colony size for M. ichthyoblabe was small and limited to approximately 300 μm, while larger colonies were mainly formed by M. aeruginosa and M. wesenbergii respectively. These results imply that the strategies used by morphospecies to allow colonies to tolerate intra-colony light limitation might be different; M. aeruginosa benefited from a reticular growth pattern, and M. wesenbergii colonies were large (500 μm), obtaining a large thickness by lowering cell concentration. The results obtained in this work suggest that M. aeruginosa and M. wesenbergii had more advantages regarding intra-colony light usage, colony size level and bloom formation ability in summer and autumn.
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Affiliation(s)
- Ganyu Feng
- College of Environment, Hohai University, Nanjing 210098, Jiangsu, China; Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, Jiangsu, China
| | - Wei Zhu
- College of Environment, Hohai University, Nanjing 210098, Jiangsu, China.
| | - Siyuan Hu
- College of Environment, Hohai University, Nanjing 210098, Jiangsu, China; Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, Jiangsu, China
| | - Zongpu Xue
- College of Hydrology and Water Resources, Hohai University, Nanjing 210098, Jiangsu, China
| | - Ruochen Wang
- College of Environment, Hohai University, Nanjing 210098, Jiangsu, China
| | - Huaimin Chen
- College of Environment, Hohai University, Nanjing 210098, Jiangsu, China
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Xiao M, Li M, Reynolds CS. Colony formation in the cyanobacterium
Microcystis. Biol Rev Camb Philos Soc 2018; 93:1399-1420. [DOI: 10.1111/brv.12401] [Citation(s) in RCA: 176] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 01/16/2018] [Accepted: 01/24/2018] [Indexed: 02/07/2023]
Affiliation(s)
- Man Xiao
- College of Natural Resources and Environment Northwest A & F University Yangling 712100 China
- Australian Rivers Institute, School of Environment and Science Griffith University Nathan Queensland 4111 Australia
| | - Ming Li
- College of Natural Resources and Environment Northwest A & F University Yangling 712100 China
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Xiao M, Willis A, Burford MA. Differences in cyanobacterial strain responses to light and temperature reflect species plasticity. HARMFUL ALGAE 2017; 62:84-93. [PMID: 28118895 DOI: 10.1016/j.hal.2016.12.008] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 12/24/2016] [Accepted: 12/29/2016] [Indexed: 06/06/2023]
Abstract
Microcystis aeruginosa and Cylindrospermopsis raciborskii are two cyanobacterial species that dominate freshwaters globally. Multiple strains of each species with different physiology occur, however, many studies have focused only on one or two strains, limiting our understanding of both strain variation and characterisation of the species. Therefore, in this study we examined the variation in growth and morphology of multiple isolates of both species, isolated from two adjacent Australian reservoirs. Four M. aeruginosa strains (=isolates) (one colony-forming, three single-celled morphology) and eight C. raciborskii isolates (five with straight trichomes, three with coiled trichomes) were cultured individually in a factorial designed experiment with four light intensities (L: 10, 30, 50 and 100μmol photons m-2s-1) and two temperatures (T: 20 and 28°C). The specific growth rate (μ), cell volume, and final cell concentration was measured. The light attenuation coefficient (kj), a measure of self-shading, was calculated. The results showed that the intraspecific variation was greater than the interspecific variation. The μ of all isolates of M. aeruginosa and C. raciborskii ranged from 0.16 to 0.55d-1 and 0.15 to 0.70d-1, respectively. However, at a specific light and temperature the mean μ of all M. aeruginosa isolates and C. raciborskii isolates were similar. At the species level, M. aeruginosa had higher growth rates at higher light intensity but lower temperature (L100T20), while straight C. raciborskii had higher growth rates at lower light intensity but higher temperature (L50T28), and coiled C. raciborskii had higher growth rates at higher light intensity and higher temperature (L100T28). The final cell concentrations of M. aeruginosa were higher than C. raciborskii. However, C. raciborskii isolates had greater variation in μ, kj and cell volume than M. aeruginosa. kj varied with light and temperature, and decreased with surface-to-volume ratio within each species. kj was lower for M. aeruginosa compared to C. raciborskii as expected based on cell size, but interestingly, C. raciborskii coiled isolates had lower kj than the straight isolates suggesting lower effect of self-shading. This study highlights the extent of strain variation to environmental conditions and to species variability.
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Affiliation(s)
- Man Xiao
- Australian Rivers Institute, Griffith University, 170 Kessels Road, Nathan, Queensland 4111, Australia; School of Environment, Griffith University, 170 Kessels Road, Nathan, Queensland 4111, Australia.
| | - Anusuya Willis
- Australian Rivers Institute, Griffith University, 170 Kessels Road, Nathan, Queensland 4111, Australia
| | - Michele A Burford
- Australian Rivers Institute, Griffith University, 170 Kessels Road, Nathan, Queensland 4111, Australia; School of Environment, Griffith University, 170 Kessels Road, Nathan, Queensland 4111, Australia
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Species-dependent variation in sensitivity of Microcystis species to copper sulfate: implication in algal toxicity of copper and controls of blooms. Sci Rep 2017; 7:40393. [PMID: 28079177 PMCID: PMC5227962 DOI: 10.1038/srep40393] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 12/06/2016] [Indexed: 01/08/2023] Open
Abstract
Copper sulfate is a frequently used reagent for Microcystis blooms control but almost all the previous works have used Microcystis aeruginosa as the target organism to determine dosages. The aim of this study was to evaluate interspecific differences in the responses of various Microcystis species to varying Cu2+ concentrations (0, 0.05, 0.10, 0.25, and 0.50 mg L−1). The half maximal effective concentration values for M. aeruginosa, M. wesenbergii, M. flos-aquae, and M. viridis were 0.16, 0.09, 0.49, and 0.45 mg L−1 Cu2+, respectively. This showed a species-dependent variation in the sensitivity of Microcystis species to copper sulfate. Malonaldehyde content did not decrease with increasing superoxide dismutase content induced by increasing Cu2+, suggesting that superoxide dismutase failed to reduce Cu2+ damage in Microcystis. Considering the risk of microcystin release when Microcystis membranes are destroyed as a result of Cu2+ treatment and the stimulation effects of a low level of Cu2+ on growth in various species, our results suggest that copper sulfate treatment for Microcystis control could be applied before midsummer when M. aeruginosa and M. viridis are not the dominant species and actual amount of Cu2+ used to control M. wesenbergii should be much greater than 0.10 mg L−1.
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