Oxygen Consumption and Isotope Fractionation in Marine Phytoplankton

海洋浮游植物的氧气消耗和同位素分馏。浮游植物利用氧气进行光合作用和呼吸作用。光合作用中氧的利用直接影响碳素吸收效率，因此对初级生产力的衡量具有重要影响。这项研究集中于浮游植物通过两个鲜为人知的过程--交替呼吸和氯呼吸--对氧气的利用。替代呼吸作用和氯呼吸作用有可能利用大量可用能量，而不提供光合作用产生的生长物质的益处，特别是在光线明亮的水域。此外，替代呼吸作用最近被确定为可能对天然水域的氧同位素组成产生重大影响的过程。据推测，氯呼吸作用也可能对海水中的同位素特征有贡献。该项目将使用稳定的同位素测量和浮游植物吸氧的生理特征，包括蓝藻聚球藻、甲藻、微小原甲藻和硅藻、中肋骨骨藻等。这项实验工作将提供各种环境条件下氯呼吸和交替呼吸的发生和活动的信息。这项工作的结果将为改进对海洋光合作用(生产力)的估计提供关键信息。此外，稳定的同位素数据有助于解释用于古气候学(历史温度记录)的氧同位素数据和估计全球范围内初级和次生生产的平衡(自养和异养)。该项目将包括中学教师通过环境科学教育伙伴关系担任暑期研究助理，并将包括研究生培训。

Todd M. KanaIOS - 0727488Oxygen consumption and isotope fractionation in marine phytoplankton.Phytoplankton use oxygen for both photosynthesis and respiration. Oxygen use in photosynthesis directly effects the efficiency of carbon uptake, and therefore it has an important impact on measures of primary production. This research focuses on oxygen use in phytoplankton by two poorly understood processes, alternative respiration and chlororespiration. Alternative respiration and chlororespiration have the potential to use a significant amount of available energy without providing the benefit of growth substances produced by photosynthesis, particularly in brightly lit waters. In addition, alternative respiration has recently been identified as a process that may have a significant effect on the oxygen isotope composition of natural waters. It is hypothesized that chlororespiration may also contribute to the isotopic signature in marine waters. This project will use stable isotope measurements and physiological characterizations of oxygen uptake in phytoplankton, including the cyanobacterium Synechococcus, the dinoflagellate, Prorocentrum minimum, and the diatom, Skeletonema costatum, among others. The experimental work will provide information on the occurrence and activity of chlororespiration and alternative respiration under various environmental conditions. The results of this work will provide critical information for improving estimates of photosynthesis (productivity) in the oceans. In addition, the stable isotope data aid in the interpretation of oxygen isotope data that are used for paleoclimatology (historical temperature records) and estimates of the balance of primary and secondary production (autotrophy and heterptrophy) at the global scale. This project will include secondary school teachers as summer research assistants through the Environmental Science Education Partnership, and will include graduate student training.