Ecological significance of the Antarctic sea ice -Experimental study on occurrence of micro habitats-

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K20050
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Research Field: Environmental analyses and evaluation and related fields
• Research Institution: National Institute of Polar Research
• Principal Investigator: Odate Tsuneo 国立極地研究所, 研究教育系, 教授 (60224250)
• Project Period (FY): 2017-06-30 – 2020-03-31
• Keywords: 海洋生態 / Antarctic Ocean / Sea ice biota / Micro habitats / Alternative pathway

Outline of Final Research Achievements

The main place where sea ice is produced in the Antarctic Ocean is considered to be the continental coastal area exposed to the extremely cold wind (katabatic wind) that blows over the continental ice sheet. The intensity of the katabatic wind affects the mixing intensity in the coastal ocean. In this study, sea ice production experiments were conducted by changing the mixing intensity. Phytoplankton strain dominated in the seasonal sea ice zone of the Antarctic Ocean was added to the filtered seawater used in the experiments. After the experiments, the concentrations of chlorophyll a in the produced sea ice were measured. The higher the amount of phytoplankton incorporated into the sea ice were observed under the higher the mixing intensity. This result suggests that even in the Antarctic field, a larger amount of phytoplankton may be incorporated into sea ice in a sea area with a stronger katabatic wind.

Free Research Field

生物海洋学

Academic Significance and Societal Importance of the Research Achievements

本研究では、今後の南極海における炭素循環や食物連鎖の研究に新たな道筋を提案することができた。冬季に南極大陸沿岸で生成した海氷は、数か月かけて沖合の低緯度側へ運ばれ、夏を迎えると融解する。そこで海氷内のマイクロハビタットは崩壊し、生物相は海洋表層へ放出されることになる。一般に海洋生態系における一次有機物は、現場の植物プランクトンの光合成によって生産されると考えられている。南極海季節海氷域においては、現場の一次生産に加え、海氷によって輸送される有機物の放出が、食物連鎖に加わっているものと推察される。今後の研究では、こうした別経路の有機物供給の貢献度を明らかにする必要がある。