| 研究課題/領域番号 |
18K13833
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| 研究機関 | 埼玉大学 |
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研究代表者 |
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| 研究期間 (年度) |
2018-04-01 – 2021-03-31
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| キーワード | Antioxidants / Extreme light / Light stress / Macrophyte Interactions / Oxidative stress / Stress recovery / Varying light |
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| 研究実績の概要 |
Responses of Phormidium ambiguum and Microcystis aeruginosa exposure to different light intensities (0,10,30,50,100,300,600 μmol/m/s PAR) for 2- and 8-days periods were tested. Considering the OD730, chlorophyll content, H2O2 and antioxidant responses (AOX), both species were negatively affected by >30 and < 50 PAR (30 and 50 PAR favorable for both species). M. aeruginosa has a higher tolerance for extreme light conditions than P. galeata. The varying light conditions (0 to max 300 or 600 PAR) revealed that AOX of both species responded to H2O2. The H2O2 AOX levels of two species were. Exposure to 500, 1000 and 1500 μmol/m/s PAR revealed that M. aeruginosa becomes chlorosis after 6 days. The interaction of M. aeruginosa with aquatic macrophyte, E. densa was tested under different PAR intensities (0, 50, 100, 200, and 300 PAR).The 7-day experiment revealed that the interaction was negative for both species and the light intensity is a detrimental factor of the interaction. Under favorable light conditions 50 μmol/m/s PAR for M. aeruginosa and 100 μmol/m/s PAR for E. densa both species were strong. The E. densa can be used to reduce the M. aeruginosa; however, only under the extreme light conditions for M. aeruginosa. The field observation conducted in Kausmigaura revealed that M. aeruginosa is starting to grow in the lake with water temperature 10±0.8 C. Based on the present findings, exposure to strong lights can suppress cyanobacteria; however, further research needed to prevent the recovery of cyanobacteria after stress exposure.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
3: やや遅れている
理由
Currently, investigating the recovery phase of cyanobacteria after exposure to extreme light (~1000 μmol/m/s PAR). It is required to understand the response of cyanobacteria to different light conditions with time and their recovery after stress prior to the field observations and applications. The combination of light stress, together with other factors that can suppress cyanobacterial growth (macrophytes allopathy, turbulence, and flow velocity), should be conducted. The flow velocity research was delayed due to the construction of a new turbulence-free circulatory velocity device. The field experiments and applications to be started this year.
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| 今後の研究の推進方策 |
The flow velocities effect from stagnant to high (0, 2, 5, 8, 10 cm/s) will be tested, and the experiment will be combined with extreme light conditions (500, 100 and 1500 μmol/m/s PAR). The recovery of cyanobacteria after exposure to stress (light or/and flow velocity) will be studied to understand post-stress recovery and adaptation. The macrophyte (E. densa) allopathy can be used as an additional approach that can be combined with light exposure to control cyanobacteria. The cyanobacteria-macrophyte coexistence conditions will be further tested under different light conditions. Due to global warming, coastal water bodies such as lakes and rivers could experience salinity intrusion or further increase of the salinity. We will test the low to high salinity (0, 2.5, 5, 7.5 and 10 ppm) effect on the cyanobacteria and will be combined under different light conditions. The growth of cyanobacteria in reservoirs under seasonal temperature conditions will be tested. Under such temperatures and cyanobacteria densities, the effect of different light intensities will be tested. Aiming the control of cyanobacteria by increasing the stress exceeding the threshold H2O2 levels, combinations of light stress together with other factors (velocity, temperature and if possible macrophytes) will be tested in a reservoir/lake.
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| 次年度使用額が生じた理由 |
We decided to keep the amount of ￥186,199 for the next fiscal year as we have planned following works,1.Attend foreign conferences and workshops related to Cyanobacteria, 2.Do more filed works in Kasumigaura lake on Cyanobacteria light response and change of responses with seasonal factors, 3.Pay English correction charges and manuscript publication charges.
However, due to the current COVID19 situation, conference attendance is uncertain. Therefore, the remain budgets will be utilized for more field and laboratory research.
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