Effect of oligotrophication on protective mechanism against strong light and taxa composition of phytoplankton

2023 Fiscal Year Final Research Report

• Project/Area Number: 22K14937
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 40030:Aquatic bioproduction science-related
• Research Institution: Hiroshima University
• Principal Investigator: Ohara Shizuka 広島大学, 統合生命科学研究科(生), 特任助教 (10878276)
• Project Period (FY): 2022-04-01 – 2024-03-31
• Keywords: 植物プランクトン / 貧栄養化 / 強光阻害 / 非光化学消光 / 分類群組成 / 珪藻類 / 鞭毛藻類 / 瀬戸内海

Outline of Final Research Achievements

Diatoms, which are major primary producers in the ocean, and flagellates, which include species harmful to fishery and capable of vertical migration, were selected. Comparing the maximum value of strong light defense mechanism (non-photochemical quenching: NPQ) of each species of 8 diatoms and 3 flagellates, 1 diatom and 1 flagellate had low NPQ ability. It was suggested that these two species have a mechanism of high-light avoidance other than NPQ, including physical avoidance by vertical migration. Then, the difference of NPQ change under phosphorus limitation was compared for these 11 species, and it was indicated that many diatoms tended to be weak to the combined stress of low nutrient and high light, that both diatoms and flagellates had the species which were advantageous and disadvantageous under the oligotrophic and high light, and that the response to this combined stress might be different by species even in the same genus.

Free Research Field

浮遊生物生態学

Academic Significance and Societal Importance of the Research Achievements

強光防御機構である非光化学消光（NPQ）に着目した研究は陸上植物では盛んである。本研究で対象とする珪藻についてもいくつか研究例があるが，その多くは干潟の底生珪藻や極地に生息する種に関する研究で，瀬戸内海のような沿岸域に代表的な浮遊性珪藻類や鞭毛藻類のNPQ能に関する知見は不足している。一方，瀬戸内海では珪藻類減少による生産力の低下や有害な鞭毛藻類赤潮による漁業被害に悩まされており，植物プランクトン種遷移をコントロールしうるNPQ能の違いを理解することは，基礎生産力低下の要因や有害鞭毛藻類赤潮の発生機構の解明に繋がると期待される。