Oxygen Consumption and Isotope Fractionation in Marine Phytoplankton

海洋浮游植物的氧消耗和同位素分馏。浮游植物利用氧气进行光合作用和呼吸作用。光合作用中的氧利用直接影响碳吸收效率，因此对初级生产指标有重要影响。本研究的重点是浮游植物通过两个鲜为人知的过程，交替呼吸和氯呼吸的氧气利用。替代呼吸和氯呼吸有可能使用大量的可用能量，而不提供光合作用产生的生长物质的好处，特别是在明亮的水域。此外，最近已确定替代呼吸是一个可能对天然水体氧同位素组成产生重大影响的过程。据推测，氯呼吸也可能有助于海洋水域的同位素特征。该项目将使用稳定同位素测量和浮游植物摄氧量的生理特征，包括蓝藻聚藻、鞭毛藻、最小原藻和硅藻、骨骸藻等。实验工作将提供在不同环境条件下氯呼吸和替代呼吸的发生和活动的资料。这项工作的结果将为提高对海洋光合作用（生产力）的估计提供关键信息。此外，稳定同位素数据有助于解释用于古气候学（历史温度记录）和估计全球尺度上初级和次级生产（自养和异养）平衡的氧同位素数据。该项目将通过环境科学教育伙伴关系邀请中学教师担任暑期研究助理，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.