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一直在增加。这种辐射，类似于可见光，穿透到水中，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无根藻类。我用人工培养的绿藻、椭球小球藻和天然湖泊的浮游藻类得到了以下结果。在太阳紫外线照射下，小球藻的光合速率和细胞生长速率下降；太阳紫外线A（波长320 ~ 400nm）对细胞生长的抑制作用较强，紫外线B（波长280 ~ 320nm）对细胞生长的抑制作用最强，紫外线A对细胞生长的抑制作用中等。只有紫外线B对DNA的损伤负责，这是由藻类细胞中胸腺素二聚体的产生确定的。采用平板菌落法对浅水湖泊中分离的绿藻进行了生存能力评价。在强太阳辐射下，即在阳光充足的条件下暴露4小时，藻类几乎100%死亡。用13C法和氧法测量了浮游植物种群的原位光合速率。在阳光充足的日子里，在湖泊的浅层处，紫外线A的作用降低了速率。本研究表明，太阳紫外线辐射也对浮游动物的垂直迁移起作用。

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。