2012 Fiscal Year Final Research Report

Development and application of novel methods for diagnosis of phytoplankton physiological status

Research Project

Project/Area Number	22710003
Research Category	Grant-in-Aid for Young Scientists (B)
Allocation Type	Single-year Grants
Research Field	Environmental dynamic analysis
Research Institution	The University of Tokyo
Principal Investigator	SATO Mitsuhide 東京大学, 大学院・農学生命科学研究科, 助教 (60466810)
Project Period (FY)	2010 – 2012
Keywords	生物海洋 / 植物プランクトン
Research Abstract	Various methods to diagnose phytoplankton physiological status were applied to cultured and natural phytoplankton populations and their validity was examined. In this process, some cultures of oceanic pico- and nanophytoplankton were established. Among them, it was confirmed that measurement of phosphate monoesterase and diesterase activities using fluorogenic substrates in combination with a fluorescent probe ELF-97 were very effective in detecting phosphorus limitation of phytoplankton. By applying this method in the North and South Pacific, the map of phosphorus limitation was drawn throughout the Pacific Ocean. From kinetics studies, it was found that phosphate diesters are recycled much slower than monoesters in the surface water of the tropical Pacific, which is an important result for biogeochemical cycles of phosphorus.