JpGU-AGU Joint Meeting 2017

講演情報

[JJ] ポスター発表

セッション記号 A (大気水圏科学) » A-OS 海洋科学・海洋環境

[A-OS31] [JJ] 近海・縁辺海・沿岸海洋で海洋学と古海洋学の連携を探る

2017年5月20日(土) 15:30 〜 17:00 ポスター会場 (国際展示場 7ホール)

コンビーナ:磯辺 篤彦(九州大学応用力学研究所)、加 三千宣(愛媛大学沿岸環境科学研究センター)、木田 新一郎(九州大学・応用力学研究所)

[AOS31-P01] 堆積物記録に基づく瀬戸内海の過去150年にわたる低次生産量の変動ー外洋・陸起源の栄養塩はどんな影響を与えてきたかー

*槻木 玲美1加 三千宣2谷 幸則3郭 新宇2大森 浩二4武岡 英隆2 (1.松山大学 法学部、2.愛媛大学 沿岸環境科学研究センター、3.静岡県立大学 食品栄養科学部環境生命科学科、4.愛媛大学 社会共創学部)

キーワード:基礎生産、色素、瀬戸内海、黒潮、古海洋学、富栄養化

We examined fossil pigments in a 210Pb-dated sediment core to document the temporal variations in phytoplankton biomass over the past 150 years in a semienclosed bay, Beppu Bay, in the western Seto Inland Sea, Japan. The flux of fossil pigments was used as an index of phytoplankton biomass, which we reconstructed after removing the effect of post-burial degradation on the concentrations of fossil pigments.
The flux doubled from the 1960s to the early 1970s, decreased or remained stable in the early 1980s, and increased again from the late 1980s to the early 1990s. The first increase in phytoplankton biomass during the 1960s was likely caused by eutrophication due to an increase in terrestrial nutrient fluxes from watersheds. The decreasing phytoplankton biomass in the early 1980s was likely related to the establishment of a sewage treatment system that reduced the terrestrial nutrient fluxes to the sea. However, the terrestrial nutrient fluxes could not explain the second increase from the late 1980s to the early 1990s. Intensification of the influx of nutrients from the shelf slope to the sea was likely the cause of the second increase in phytoplankton biomass. This is supported by the inverse relationship between phytoplankton biomass and sea level at the shelf slope, the latter being an index of the intensity of the influx of oceanic nutrients from the shelf slope to the sea. The supply of oceanic nutrients may be therefore a critical factor in the determination of primary production in the western Seto Inland Sea.