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Alternative TitleStudies on the photophysiology of Skeletonema costatum (Bacillariophyta) and Emiliania huxleyi (Chrysophyta)
Thesis Advisor高坤山
Degree Grantor中国科学院水生生物研究所
Place of Conferral水生生物研究所
Keyword太阳紫外辐射 中肋骨条藻 赫氏颗石藻 光化学效率 光合固碳 海水酸化
Abstract人类活动导致的阳光紫外辐射(UVR)增加、大气CO2浓度升高以及表层海洋酸化等环境变化,如何影响海洋生态系统,是倍受关注的科学问题。为此,阳光紫外辐射的变化和海水酸化如何影响海洋初级生产力的问题是海洋科学研究的焦点之一。本文以全球海洋广泛分布的的中肋骨条藻(硅藻)和赫氏颗石藻(金藻)为研究材料,探讨了阳光紫外辐射和海洋酸化对其光合作用及生长的影响,主要结果如下: 阳光紫外辐射,抑制中肋骨条藻的光化学活性及光合固碳量,其抑制作用与细胞接受的光背景及辐射量和强度有关。从海水原位分离出的中肋骨条藻(WS),对UVR导致的PSII损伤,具有较快的修复能力;而室内保种十几年的品系(IS),经UVR损伤后,修复速度缓慢。即使在光变环境下(模拟水体垂直混合过程),IS受到UVR的抑制率依然大于WS。将IS中肋骨条藻品系,置于阳光下长期培养时,实验初始阶段,IS的生长速率远远低于WS,3天后,两品系的生长速率达到相同水平,UVR对光合固碳引起的抑制作用也均等,显示IS适应阳光后,修复UVR损伤的能力增强。然而,抵御紫外辐射的紫外吸收物质,在适应阳光辐射的过程中并没有增加。 作为钙化藻类的颗石藻,除了光合固碳外,还进行钙化固碳。UVR对两种固碳作用都起到抑制作用;从相对抑制率来看,钙化作用受UVR的抑制作用较大。另外,UVR对颗石藻光合及钙化的抑制,在水体混合(光变)条件下减小。在长期培养过程中,随着对阳光紫外辐射的适应,颗石藻细胞增大,颗石片增厚,紫外吸收物质含量增加,抵御UVR的能力增加。另一方面,当将颗石藻在下调碱性的海水(模拟海洋酸化)中培养时,因海水碳酸盐体系的变化,颗石藻的钙化过程受到明显抑制,细胞增大,光合作用对无机碳的亲和力也下降了。在此海水酸化状态下,UVR对颗石藻的光合与钙化的抑制作用增大。
Other AbstractGlobal changes caused by industrial activities are known as enhanced solar ultra-violet radiation (UVR), increased atmospheric CO2 concentration and ocean acidification. How such environmental changes would influence marine ecosystems is an important issue for marine scientists. One of the most interested questions is to see how UVR and ocean acidification affect marine primary producers. Therefore, we investigated the effects of UVR and ocean acidification on the photosynthesis and growth of the diatom Skeletonema costatum and the cocolithorphore Emiliania huxleyi, two cosmopolitan and ecologically important phytoplankton. The main results are as follows: Solar UVR inhibited the photochemical activity and photosynthetic carbon fixation of the S. costatum cells. The extent of inhibition depends on light history of the cells, doses and intensity of irradiation. In contrast to the cells of naturally grown S. costatum cells (WS), indoor grown strain (IS), which had been grown under low PAR for decades, was more sensitive to solar UVR and slower in repairing the damage of PSII caused by UVR. Even under changing levels of solar radiation simulated for vertical mixing, solar UVR still induced higher inhibition in IS than in WS. During long-term exposures to solar radiation, the specific growth rate was much lower in IS than in WS at the beginning, then increased 3 days later to reach an equivalent level as that of WS until the end of experiment (10th day). It indicated that the repair processes for UVR-induced damages must have been accelerated for IS, however, the contents of UV-absorbing compounds was not increased during the long-term acclimation to solar radiation. E. huxleyi, as a calcifying phytoplankton, operates two kinds of carbon fixation: photosynthesis and calcification. Both processes were inhibited by UVR, but UVR-induced inhibition was higher in calcification than in photosynthesis. However, changing levels (in contrast to constant one) of radiation simulated for vertical mixing decreased the deleterious effects of UVR. During a long-term experiment, the cells became acclimated to solar radiation, showing higher resistance to UVR. During such an acclimation, the cells became larger with thicker cocolith layer and more UV-absorbing compounds. On the other hand, when E. huxleyi cells were grown under simulated oceanic acidification conditions, calcification was inhibited due to of the chemical changes in the seawater carbonate system. At the same time, photosynthetic affinity to inorganic carbon decreased under the acidified conditions.
Document Type学位论文
Recommended Citation
GB/T 7714
关万春. 骨条藻和颗石藻光生理学研究[D]. 水生生物研究所. 中国科学院水生生物研究所,2008.
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