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对海洋生产的影响：评估紫外线的影响。来自太阳的紫外线辐射(UVR，290-400纳米)在许多海洋环境中穿透到相当深的地方，各种研究表明其生态重要性。平流层臭氧消耗通过增加对生物有害的短波紫外线(290-320 nm)的水平，在不同位置不同程度地改变了太阳LTVR的光谱组成。以前的工作表明，UVB和较长波长的UVA(320-400 nm)都影响海洋碳循环，主要是通过影响构成海洋食物网基础的浮游植物和浮游细菌。浮游植物负责固碳，浮游细菌在营养物质矿化过程中起着至关重要的作用，并为高等生物提供营养纽带。在臭氧和水的透明度变化期间，评估紫外线对这些过程的影响需要准确的光谱相关性知识。这种相关性由生物权重函数(BWF)来描述。在过去的二十年里，人们致力于解决生物过程中的生物量，控制水环境中初级生产量的速率(即光抑制)。然而，与紫外线对浮游植物影响的报道相比，关于紫外线对浮游细菌的影响和影响的研究还处于相对初级阶段。以前关于浮游细菌的工作仅限于广谱分析(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而增加的UVB的影响。这个项目的主要目标是开发生物加权函数，以DNA、RNA和蛋白质合成为代表的生物过程来抑制浮游细菌的生产。将使用多色光系统确定不同海洋环境(切萨皮克湾和墨西哥湾)抑制DNA、RNA和蛋白质合成的生物加权函数，并与测量的浮游植物的类似函数进行比较。将开发模型，并将其与生产的现场测量进行比较，并检查是否存在显著差异。对分离前和分离后的样品进行的实验将表明浮游细菌耦合如何影响紫外线反应。时间序列分析将定义反应如何与暴露相关，以及损伤是否被光重新激活所抵消。这项研究将增加我们对不同环境中浮游细菌自然组合的光谱敏感性的理解，以及紫外线在控制海洋生态系统中的作用，特别是参考与平流层臭氧消耗相关的紫外线B的增加。

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.