Ultraviolet Radiation Induced Changes in the Patterns of Production and Composition of Biochemical Compounds in Antarctic Phytoplankton

有足够的证据表明，目前的入射紫外线辐射（UVR, 280-400nm）水平正在损害南大洋浮游植物的生产力。然而，为了准确而明确地预测紫外线辐射对南极海洋食物网和海洋生物地球化学循环的影响，对这些发现进行外推的努力受到了不确定性的影响。对南极海洋生态系统的估计影响从微不足道到灾难性的不等。这种差异是由于在UVR光生物学和光化学的关键领域缺乏信息。一般来说，研究都是基于宽带UVR，并没有考虑到浮游植物在UVR波段不同波长的竞争反应。如果我们要了解紫外线增强对海洋浮游植物碳同化的影响及其对食物网和生物地球化学循环的影响，这些信息至关重要。在南极这样的地区尤其如此，那里平流层臭氧浓度每年春天可以减少约50%，改变了浮游植物在生长季节接受的中波紫外线（280-320纳米）和长波紫外线（320-400纳米）辐射的比例。该项目将系统地调查在光谱确定的条件下南极浮游植物细胞内生化化合物的生产速率和组成的变化。对南极浮游植物的实验室培养和自然种群进行调查，以了解1)浮游植物细胞生化过程如何受到不同UVR波长和可见光之间相互作用的影响；2)不同浮游植物分类群对UVR的敏感性如何变化；3)这种敏感性差异是否导致一种植物优于另一种植物。紫外线照射对浮游植物细胞营养吸收的影响也将被研究。这一信息将有助于确定紫外线辐射在南大洋浮游植物动态中的作用。

Goes0126150There is sufficient evidence to show that present levels of incident ultraviolet radiation (UVR, 280-400nm) are impairing phytoplankton productivity in the Southern Ocean. Yet, efforts at extrapolating these findings to allow accurate and unambiguous predictions of the consequences of UVR on the Antarctic marine food web and biogeochemical cycles in the sea have been confounded with uncertainty. Estimated impacts to the Antarctic marine ecosystem range from insignificant to catastrophic. This disparity has been attributed to lack of information in key areas of UVR photobiology and photochemistry. Generally, studies have been based on broadband UVR, and do not take into account competing responses of phytoplankton at different wavelengths across the UVR waveband. Such information is critical if we are to understand the consequences of UVR enhancement on carbon assimilation by marine phytoplankton and its consequences for the food web and biogeochemical cycles. This is especially true in regions like the Antarctic where stratospheric ozone concentrations can decrease by about 50% each spring altering the proportion of UVB (280-320nm) and UVA (320-400nm) radiation that phytoplankton receive during their growth season. This project will systematically investigate changes in the production rates and composition of biochemical compounds within Antarctic phytoplankton cells under spectrally defined conditions. Investigations of both laboratory cultures and natural populations of Antarctic phytoplankton will be undertaken to understand 1) how phytoplankton cellular biochemical processes are impacted by the interplay between the different UVR wavelengths and visible light, 2) how UVR sensitivity varies across taxonomic groups of phytoplankton and 3) whether this difference in sensitivity is responsible for the dominance of one species over the other. The effect of UVR exposure on nutrient uptake by phytoplankton cells will also be studied. This information will help ascertain the role of UVR in the phytoplankton dynamics of the Southern Ocean.