Effects of Ozone-Related Increased UV-B Fluences on Photosynthesis, Photoadaptation and Viability of Phytoplankton in Antarctic Waters

南极洲上空平流层臭氧浓度的降低导致入射在地球表面“臭氧空洞”下的UV-B部分的紫外线辐射水平增加。现在全世界都担心，这种增加的紫外线辐射通量可能会对南大洋的海洋生态系统造成严重损害。该项目包括实地和实验室研究，将有助于确定UV-B辐射水平增强对浮游植物的影响，并将这种影响与覆盖的臭氧浓度联系起来。由美国国家科学基金会在帕尔默站操作的紫外光谱辐射计测定的紫外线水平将直接适用于解释观察到的生物效应。主要关注UV-B辐射对光合作用速率的影响，对DNA造成的细胞活力损失的损害，以及浮游植物通过产生特殊保护色素将细胞紫外线损害降至最低的速度和程度。还将确定主要浮游植物物种或群体对UV-B的不同敏感性，因为这种差异可能对南极水域的食物网结构产生重要影响。由于该项目的活动将涵盖从9月到12月的期间，因此产生的数据集应该包括臭氧层空洞最大发展时期以及夏至时间。这个项目很重要，因为它将阐述之前的发现，并详细说明紫外线对浮游植物的损害程度和性质，以及评估细胞可以针对它建立的各种防御措施。

Decreased concentrations of ozone in the stratosphere over Antarctica have resulted in increased levels of ultraviolet radiation in the UV-B portion of the spectrum incident at the earth's surface beneath the 'ozone hole'. There is now world-wide concern that this enhanced flux of UV radiation may cause serious harm to the marine ecosystem in the Southern Ocean. This project, which includes field and laboratory studies, will help to determine the effects of enhanced levels of UV-B radiation on phytoplankton, and to relate such effects to overlying ozone concentrations. UV levels determined from the NSF-Operated UV- Spectroradiometer at Palmer Station will be directly applicable to the interpretation of observed biological effects. Primary attention will be given to the effects of UV-B radiation on photosynthetic rates, on damage to DNA with resulting loss of cell viability, and on the rates and extent to which phytoplankton can minimize cellular UV damage by production of specialized protective pigments. Differential sensitivity to UV-B of dominant phytoplankton species or groups will also be determined, as such differences might have important consequences on the structure of the food web in antarctic waters. As the project's activity will cover the period from September through December, the resulting data set should encompass the period of maximal development of the ozone hole, as well as the time of the summer solstice. This project is important because it will elaborate previous findings and address in detail the extent and the nature of ultraviolet damage to phytoplankton, as well as evaluate the kinds of defenses cells can muster against it.