Patterns and Sources of Variability in Biological Weighting Functions for UVR Inhibition of Primary Production in California Coastal Waters

在过去20年中，除热带地区外，所有纬度地区都发生了紫外线辐射气候学的重大变化，对沿海海洋学产生了潜在的重大影响。迫切需要了解并能够预测紫外线辐射对沿海初级生产的影响；部分原因是由于碳固定在生态系统动力学中起着核心作用，部分原因是由于各种未经检验的情景表明，生产模式会随着UVR气候变化而变化，部分原因是出于对这些情景可能对沿海社会产生的潜在影响的关注。在美国国家科学基金会的资助下，我们已经证明太阳紫外线辐射（UVR）对海洋初级生产的抑制在南大洋的浮游植物、大型藻类、外缘微藻和冰藻中普遍存在。为了建立太阳UVR对初级生产影响的光谱模型，我们测量了几种作用光谱或生物加权函数（BWFs）中的第一个，量化了自然野外条件下初级生产对UVR抑制的光谱敏感性。我们首次记录了这些光谱算法的显著可变性，并确定了这种可变性的潜在实验、分析和自然来源，但尚未对其进行测试。如果要了解紫外线辐射的光学模型和紫外线辐射对初级生产的影响之间的预测联系，就需要这些知识。缺乏对UVR效应的考虑破坏了初级生产模型的预测准确性，并忽略了UVR在改变浮游植物光生态的细胞过程中所起的调节作用。在不同的生态系统中，UVR挑战的性质可能有所不同，对食物网的相互影响也可能得到不同的平衡。1995年对圣巴巴拉海峡表层浮游植物群落的可行性研究表明，紫外线辐射可能对表层初级生产力产生重大但变化很大的影响。基于这些发现，并使用成熟的技术，我们将定义在高度多样化的加利福尼亚沿海水域中，UVR抑制初级生产的BWFs变异性的模式和来源，从而推进UVR依赖初级生产的光谱建模。该研究项目的结果还将有助于确定UVA和UVB调节浮游植物多色生物学的机制，并为全球UVB气候变化对浮游植物生态的潜在影响提供见解。

Significant changes in UVR climatology have occurred all latitudes, except the tropics, during the last 20 years with potentially significant consequences for coastal oceanography. There is a pressing need to understand and be able to forecast UVR effects on coastal primary production; in part because of the central role carbon fixation plays in ecosystem dynamics, in part because of the various but untested scenarios suggesting changes in production patterns in response to changing UVR climatology, and in part out of concern for the potential impact these scenarios might have on coastal societies. With prior NSF funding, we have documented that inhibition of marine primary production by solar ultraviolet radiation (UVR) is widespread in phytoplankton, macroalgae, epilithic microalgae and ice algae in the Southern Ocean. To advance the spectral modeling of solar UVR effects on primary production, we measured the first of several action spectra or biological weighting functions (BWFs) quantify the spectral sensitivity of primary production to UVR inhibition under natural field conditions. We documented, for the first time, the significant variability in these spectral algorithms and identified but have not tested potential experimental, analytical and natural sources of that variability. Such knowledge is required if the predictive linkages between optical models of UVR and UVR effects on primary production are to be known. Lack of consideration of UVR effects undermines the predictive accuracy of primary production models and overlooks the regulatory roles that UVR plays in modifying cell processes that define the photoecology of phytoplankton. It is likely that the nature of the UVR challenges may differ in different ecosystems and the interactive effects on food webs may be balanced differently. A feasibility study of surface phytoplankton communities in the Santa Barbara Channel during 1995 indicate a potential for significant, but highly variable, UVR effects on surface primary production rates. Based on those findings and using proven techniques, we will define the patterns and sources of variability in BWFs for UVR inhibition of primary production in highly diverse California coastal waters and, thereby, advance spectral modeling of UVR dependent primary production. The results of this research project will also help identify the mechanisms by which UVA and UVB regulate the polychromatic biology of phytoplankton and provide insights regarding potential consequences of changing global UVB climatology on phytoplankton ecology.