Complex functions of trace metals on regulation of nitrogen cycle in the subsurface ocean

2015 Fiscal Year Final Research Report

• Project/Area Number: 26550010
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Environmental dynamic analysis
• Research Institution: Nagasaki University
• Principal Investigator: TAKEDA Shigenobu 長崎大学, 水産・環境科学総合研究科(水産), 教授 (20334328)
• Co-Investigator(Renkei-kenkyūsha): WADA Minoru 長崎大学, 水産・環境科学総合研究科(水産), 教授 (70292860) ; UMEZAWA Yu 長崎大学, 水産・環境科学総合研究科(水産), 准教授 (50442538)
• Project Period (FY): 2014-04-01 – 2016-03-31
• Keywords: 海洋生態 / 物質循環 / 微量金属 / 窒素 / 植物プランクトン / 鉄

Outline of Final Research Achievements

Based on the field observations and on board incubation experiments conducted in the North Pacific Ocean, it become clear that the phytoplankton assemblages in the subsurface chlorophyll maximum layer are under severe iron-limitation, and that nitrate consumption by phytoplankton can be stimulated under iron-sufficient conditions. Although dissolved zinc and cobalt concentrations also decreased at the subsurface chlorophyll maximum layer, there was no response in phytoplankton growth in the zinc or cobalt enrichment incubation experiments. These results support a hypothesis that iron limitation stimulates nitrite release from phytoplankton cells to the surrounding water due to inhibition of nitrate metabolic pathway, and causes formation of the primary nitrite maximum in the oceanic subsurface layer.

Free Research Field

海洋生物地球化学