Response of phytoplankton assemblage to nutrient dynamics caused by environmental changes in the neritic area of Sagami Bay

Research Project

Project/Area Number	15K07536
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Multi-year Fund
Section	一般
Research Field	Aquatic bioproduction science
Research Institution	Nihon University
Principal Investigator	ARA Koichi 日本大学, 生物資源科学部, 准教授 (40318382)
Project Period (FY)	2015-04-01 – 2018-03-31
Project Status	Completed (Fiscal Year 2017)
Budget Amount *help	¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000) Fiscal Year 2017: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000) Fiscal Year 2016: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000) Fiscal Year 2015: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Keywords	プランクトン / 栄養塩 / クロロフィルa濃度 / ピコ・ナノ・マイクロ植物プランクトン / 一次生産 / 海況 / 陸・外洋起源 / 相模湾沿岸域
Outline of Final Research Achievements	In the neritic area of Sagami Bay, from the short-term variations in physicochemical properties deviated from the seasonal variation pattern, water conditions were divided into the period of normal condition (coastal water), high freshwater discharge from rivers after rainfalls, the expansion of Tokyo Bay Water, and/or the intrusion of Kuroshio Water, Oyashio Intermediate Water or deep water from the continental slope. The effects of these water conditions on phytoplankton assemblage were evaluated. Moreover, annual requirement of dissolved inorganic nitrogen and phosphorus (DIN and DIP, respectively) for phytoplankton was estimated from primary productivity, assuming a nutrient uptake molar C:N:P ratio of 106:16:1 (Redfield ratio). As a result, for annual primary production, the contribution of open-ocean-originated DIN and DIP was slightly higher than that of land-originated ones.