Significance of Solar Ultraviolet Radiation in Arctic Waters: Effects on Phytoplankton and Ichthyoplankton

9321736霍尔姆-汉森关于南极水域紫外线辐照度增加对浮游生态系统的影响已作了较为详细的研究，但在北半球高纬度地区尚未进行类似的研究。最近的证据表明，北冰洋上空的臭氧正在变薄，这表明北部海域可能会出现类似的紫外线效应。在这项提案中，我们将确定目前紫外线辐射的影响，以及紫外线辐射增加对北极高纬度浮游植物和鱼类的潜在影响。将在挪威进行的北极浮游植物研究将侧重于：(I)紫外线辐射对光合作用速率的影响和对初级生产力总体速率的影响，(Ii)细胞通过合成紫外线吸收化合物降低其对紫外线辐射的敏感性的程度，(Iii)不同物种对紫外线的抵抗力差异，以及(Iv)对北方浮游生物群落未知的DNA修复能力。这两个极地都没有进行过紫外线对浮游鱼群的伤害研究。最近发展的方法使我们能够测量紫外线对个体自由生活的卵和幼虫的DNA损伤量。这些在温带纬度地区进行的研究结果表明，损伤和修复的周期、暴露前的条件和种间差异极大地影响了对紫外线损伤的敏感性。本研究将首次尝试测量紫外线对重要极地渔业物种早期生命阶段的影响。该提案将研究人员测量紫外线损害的技能与挪威特罗姆索实验室的独特位置、合作者和技术能力结合在一起。

9321736 Holm-Hansen The effects of increased ultraviolet (UV) irradiance on planktonic ecosystems have been studied in some detail for Antarctic waters but comparable studies have not been carried out at high northern latitudes. Recent evidence has documented a thinning of ozone over Arctic seas, suggesting the potential for similar UV effects in northern waters. In this proposal we will determine the effects of present-day ultraviolet radiation, as well as the potential effects of increased UV irradiance, on phytoplankton and ichthyoplankton in high Arctic latitudes. Studies of Arctic phytoplankton, to be conducted in Norway, will focus on (i) the effects of UV radiation on photosynthetic rates and the effect on overall rates of primary production, (ii) the extent to which cells can decrease their sensitivity of UV radiation by synthesis of UV-absorbing compounds, (iii) species- specific differences in UV resistance, and (iv) DNA repair capacities which are unknown for northern plankton communites. Studies of UV damage to ichthyoplankton have not been conducted at either pole. Recently developed methods allow us to measure the amount of UV induced DNA damage in individual free-living eggs and larvae. The results of these studies, done at temperate latitudes, have shown that the diel cycle of damage and repair, the pre-exposure conditions, and interspecific differences greatly effect the susceptablility to UV damage. The present study will be the first attempt to measure the impact of UV on early life-stages of important polar fisheries species. The proposal brings together the investigators' skills in measuring UV damage together with the unique location, collaborators and technical capabilities of the laboratories in Tromso, Norway.