Allelopathic influence of low concentration Microcystis aeruginosa on Egeria densa under different light intensities

ABSTRACT

In this study, Egeria densa plants were exposed to a low concentration of (OD₇₃₀ = 0.04) Microcystis aeruginosa for seven days, under different photosynthetically active radiation (PAR) intensities (0, 50, 100, 200, and 300 µmol m⁻² s⁻¹). Experiments were conducted under controlled conditions inside incubators. The H₂O₂ content, antioxidant responses, pigmentation, and chlorophyll fluorescence parameters were measured. The biochemical parameters of E. densa varied with PAR intensity; under the 50 and 100 µmol m⁻² s⁻¹ PAR intensities, E. densa performed relatively better than under other intensities. When exposed to M. aeruginosa, the levels of the measured biochemical parameters reduced in E. densa. Under unfavourable light conditions, the optical density of M. aeruginosa was also reduced when E. densa was also present. Even at low concentrations, the presence of M. aeruginosa in the water can have a negative effect on E. densa pigmentation and physiological parameters, though E. densa also has negative effects on M. aeruginosa growth. Further studies are recommended to evaluate the responses of E. densa after prolonged exposure to M. aeruginosa and the effects of E. densa on M. aeruginosa.

KEYWORDS:

• antioxidants
• Egeria densa
• Microcystis aeruginosa
• negative effects
• oxidative stress
• pigmentation
• short duration

Disclosure statement

No potential conflict of interest was reported by the author(s).

Notes on contributors

M. D. H. Jayasanka Senavirathna is an Assistant Professor at the Graduate School of Science and Engineering and the Department of Environmental Science and Technology, Saitama University, Japan. He is working on stress responses of plants, macrophytes and cyanobacteria, and management of those, particularly in human-engineered environments. Also, he is researching on species interactions.

Guligena Muhetaer is a final year PhD student at the Graduate School of Science and Engineering, Saitama University, Japan. Her research focus is on stress responses and the management of harmful cyanobacteria.

Liu Zhaozhi is an MSc student at the Graduate School of Science and Engineering, Saitama University, Japan. His research focus is on abiotic and biotic stress responses of macrophytes.

Takeshi Fujino is a Professor at Deptartment of Environmental Science and Technology, Saitama University, Japan. His academic background is Civil and Environmental Engineering. He has several domestic and international projects in water quality management, environmental biophysics, and stream ecosystems.

Additional information

Funding

This research was funded by the Japan Society for the Promotion of Science (JSPS), JSPS KAKENHI grant number 18K13833.