Collaborative Research: UV Effects on Marine Production by Bacteria and Phytoplankton Assessing the Impact of UVB

紫外线对细菌和浮游植物海洋生产的影响：评估UVB的影响。 来自太阳的紫外线辐射（UVR，290-400 nm）在许多海洋环境中渗透到相当深的地方，各种研究表明其生态重要性。平流层臭氧消耗增加了对生物有害的短波UVB（290-320纳米）的水平，从而在不同地点不同程度地改变了太阳LTVR的光谱组成。先前的工作表明，UVB和波长较长的UVA（320-400纳米）主要通过影响构成海洋食物网基础的浮游植物和浮游细菌，影响海洋碳循环。浮游植物负责固碳，而浮游细菌在营养物质的矿化中起着至关重要的作用，并为高等生物提供营养联系。要评估臭氧和水透明度变化期间紫外线对这些过程的影响，就需要准确了解光谱依赖性。这种依赖性由生物加权函数（BWF）描述。 在过去二十年中，为解决控制水生环境中初级生产率的生物过程（即光抑制）的生物WFs问题做出了重大努力。然而，与紫外线对浮游植物的影响的报告相比，紫外线辐射对浮游细菌的影响和效果的研究还处于相对初期阶段。以前对浮游细菌的研究仅限于广谱分析（即UVA与UVB）。不幸的是，这种有限的光谱分辨率排除了预测，特别是由于臭氧消耗增加的UVB的影响。该项目的主要目标是开发生物加权函数，用于抑制浮游细菌的生产，使用DNA，RNA和蛋白质合成作为代表性的生物过程。生物加权功能的抑制DNA，RNA和蛋白质的合成将被确定为不同的海洋环境（切萨皮克湾和墨西哥湾）使用多色光制度和浮游植物测量的类似功能相比。将开发模型，并将其与现场生产测量结果进行比较，并检查是否存在重大差异。 实验前和后分级样品将表明如何浮游细菌耦合影响紫外线响应。时间序列分析将确定反应如何与暴露相关，以及损伤是否被光复活抵消。这项研究将增加我们对不同环境中浮游细菌自然聚集的光谱敏感性以及UVR在控制海洋生态系统中的作用的了解，特别是与平流层臭氧消耗相关的UVB增加。

U.V. Effects on Marine Production by Bacteria and Phytoplankton: Assessing the Impact of UVB. Ultraviolet radiation (UVR, 290-400 nm) from the sun penetrates to significant depths in many marine environments and a variety of studies have indicated its ecological importance. Stratospheric ozone depletion is changing the spectral composition of solar LTVR to varying degrees in different locations by increasing levels of biologically harmful, short wavelength UVB (290-320 nm). Previous work has shown that both UVB and the longer wavelength UVA (320-400 nm) affect marine carbon cycling, primarily through effects on phytoplankton and bacterioplankton which comprise the base of oceanic food webs. While phytoplankton are responsible for carbon fixation, bacterioplankton play a vital role in the mineralization of nutrients and provide a trophic link to higher organisms. Assessing the impact of UV on these processes during variations in ozone and water transparency requires accurate knowledge of spectral dependence. This dependence is described by a biological weighting function (BWF). Significant effort has been devoted in the last two decades to resolving BWFs for biological processes controlling rates of primary production in aquatic environments (i.e. photoinhibition). Compared to reports of UV effects on phytoplankton, however, studies of the impact and effects of UVR on bacterioplankton are in their relative infancy. Previous work with bacterioplankton has been limited to broad spectrum analysis (i.e. UVA vs. UVB). Unfortunately, such limited spectral resolution precludes prediction, particularly of the effects of increased UVB due to ozone depletion. The principal goal of this project is to develop biological weighting functions for inhibition of bacterioplankton production using DNA, RNA, and protein synthesis as representative biological processes. Biological weighting functions for inhibition of DNA, RNA, and protein synthesis will be determined for diverse marine environments (Chesapeake Bay and Gulf of Mexico) using polychromatic light regimes and compared to similar functions measured for phytoplankton. Models will be developed and compared to in situ measurements of production and examined for significant disparities. Experiments with pre- and post- fractionated samples will indicate how bacterioplankton coupling influences UV responses. Time series assays will define how response is related to exposure and whether damage is counteracted by photoreactivation. This study will increase our understanding of the spectral sensitivity of natural assemblages of bacterioplankton in diverse environments and of the role of UVR in controlling marine ecosystems with particular reference to increased UVB associated with stratospheric ozone depletion.