Effects of the solar ultraviolet radiation on the photosynthesis and survival of freshwater algae

太阳紫外线辐射对淡水藻类光合作用和生存的影响

• 批准号: 13640633
• 负责人: WATANABE Yasunori
• 金额: $ 2.18万
• 依托单位: Tokyo Metropolitan University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13640633/
• 关键词: ultraviolet radiation; solar radiation; algae; photosynthesis; phytoplankton; survival; 淡水藻類; 湖; DNA損傷

Solar ultraviolet radiation on the earth surface has been increasing recently. This radiation, similar to the visible light, penetrates into water and gives detrimental effects on various aquatic organisms. The present study aims to elucidate the effect of solar radiation on freshwater algae, including phytoplankton and sessile algae distributed in aquatic environments such as lakes and rivers. I obtained the following results using cultured green alga, Chlorella ellipsoidea, and planktonic algae from natural lakes. Photosynthetic rate and cellular growth rate of the Chlorella decreased under the solar ultraviolet conditions; strong inhibition was brought about by solar ultraviolet A (wave length 320-400nm), whereas for the cellular growth was inhibited by ultraviolet B (280-320nm) most strongly and ultraviolet A moderately. Only ultraviolet B was responsible to the damage of DNA, which was determined by production of thymin-dimmers in the algal cells. Survivability of green algae isolated from shallow lake was assessed by the plate colony method. Almost 100% death of algal population was exhibited by the exposure of strong solar radiation, i.e. sunny conditions for 4 h. Photosynthetic rate of phytoplankton populations in situ was measured with 13C method and the oxygen method. Decrease of the rate by ultraviolet A was observed on sunny days at the shallow depths in the lake. The present study revealed that solar ultraviolet radiation also responsible for the vertical migration of zooplankton.

近年来，地球表面的太阳紫外线辐射不断增加。这种辐射与可见光类似，会渗透到水中并对各种水生生物产生有害影响。本研究旨在阐明太阳辐射对淡水藻类的影响，包括分布在湖泊和河流等水生环境中的浮游植物和固着藻类。我使用培养的绿藻、椭圆小球藻和天然湖泊的浮游藻类获得了以下结果。太阳紫外线条件下小球藻的光合速率和细胞生长速率降低；太阳紫外线A（波长320-400nm）对细胞生长有强烈的抑制作用，而紫外线B（280-320nm）对细胞生长的抑制作用最强，紫外线A的抑制作用中等。只有紫外线 B 会造成 DNA 损伤，这是由藻类细胞中胸腺嘧啶二聚体的产生决定的。采用平板菌落法评估浅湖绿藻的生存能力。暴露在强烈的太阳辐射下，即阳光充足的条件下持续 4 小时，藻类种群几乎 100% 死亡。采用~(13)C法和氧气法测定原位浮游植物种群的光合速率。在阳光明媚的日子里，在湖的浅水深处观察到紫外线A的速率下降。目前的研究表明，太阳紫外线辐射也是浮游动物垂直迁移的原因。

项目成果

Katano, T., Fuki, M., WATANABE, Y.: "Identification of cultured and uncultured picocyanobacteria from a mesotrophic freshwater lake based on the partial sequences of 16S rDNA"Limnology. 2. 213-218 (2001)

Katano, T.、Fuki, M.、WATANABE, Y.：“根据 16S rDNA 的部分序列识别中营养淡水湖中培养和未培养的微微蓝细菌”Limnology。