Ozone Depletion and UV Inhibition of Photosynthesis in Arctic Kelps: Spectral and Temporal Dependence

平流层臭氧的消耗，特别是在极地地区，正在引起人们对有害紫外线辐射(主要是UVB，280-320纳米)影响的日益关注。UVB对许多生物过程都是有害的，在植物中，UVB特别针对光合作用。众所周知，在南半球春季，由于臭氧消耗，太阳UVB在南大洋的穿透率大幅增加，这对浮游植物的生产力有重大影响。这种现象在北极没有那么严重，但与臭氧有关的UVB事件的增加在过去三年里加速了。该提案涉及紫外线辐射增加对大型底栖海洋大型藻类(海藻)的影响以及渗透到北极沿海水域的紫外线辐射水平问题。海带光合作用对UVB的敏感性知之甚少。环境中紫外线效应(280-400 nm)的评估可以通过用生物加权函数(BWF；类似于作用光谱)对紫外线辐射光谱进行加权来进行。研究人员将测量北极高海拔地区大型藻类光合作用的详细BWF和UV影响动力学，重点是分布在环北极地区的海带、海带和海带。两个实验室培养的植物和孢子体采集的两个春季和一个夏季的田野季节在加拿大高北极(决心，79o30‘N；950oW)将被测量。在九个月的冰盖期间，植物暴露在不同的自然光环境中，将被检查它们对紫外线辐射的不同敏感性；还将调查植物在恢复过程中的氮状态，以抵消紫外线造成的损害。这一结果将首次量化海带栖息地潜在的紫外线暴露，以及这种暴露对北极沿海系统海藻生产力的生物影响。

Depletion of stratospheric ozone, particularly in the polar regions, is causing increased concern over the effects of harmful UV radiation (mainly UVB, 280-320 nm). UVB is damaging to many biological processes, and in plants, specifically targets photosynthesis. Large increases in the penetration of solar UVB in the Southern Ocean during the austral spring from ozone depletion is known to have significant effects on phytoplankton productivity. The phenomenon is less severe in the Arctic, but ozone related increases in incident UVB have accelerated over the last three years. This proposal addresses the question of the effects of increased UVB on large benthic marine macroalgae (kelp) and the levels of UVB that penetrates into the coastal water of the Arctic. Little is known about the sensitivity of kelp photosynthesis to UVB. Assessment of UV effects (280-400 nm) in an environmental context can be made by weighting the spectrum of UV irradiance with a biological weighting function (BWF; similar to an action spectrum). The investigators will measure detailed BWF's and the kinetics of UV effects n photosynthesis of macroalgae in High Arctic, emphasizing the kelps, Laminaria saccharina and L. solidungula, which are distributed throughout the circumpolar Arctic. Both laboratory cultured plants and sporophytes collected during two spring and one summer field season in the Canadian High Arctic (Resolute, 79o30' N; 95oW) will be measured. Plants exposed to different natural light environments during the nine-month ice covered period will be examined for difference in their sensitivity to UV radiation; the importance of the nitrogen status of the plants in recovery processes that counteract UV-induced damage will also be investigated. The results will enable the first quantification of potential UV exposure in kelp habitats and the biological effects of such exposure in terms of kelp productivity in arctic coastal systems.