[B-PT03] 生物鉱化作用（バイオミネラリゼーション）と古環境プロキシー

[BPT03-P02] セジメントトラップ試料を用いた北西太平洋亜熱帯域の浮遊性有孔虫の季節変化

*黒柳 あずみ¹、鈴木 淳²、山岡 香子²、橋本 優里³、藤井 武史⁴、近藤 俊祐⁴、湊谷 純平⁵ (1.東北大学学術資源研究公開センター東北大学総合学術博物館、2.産業技術総合研究所 地質情報研究部門、3.東北大学理学部地圏環境科学科、4.KANSOテクノス、5.石油天然ガス・金属鉱物資源機構)

キーワード：浮遊性有孔虫、セジメントトラップ、西部北太平洋

Planktic foraminifers are marine plankton with calcite tests, and the ocean surface environment can be reflected in their abundance, assemblage and shell chemical composition. Thus, planktic foraminifera plays an important role in the reconstruction of paleoenvironments. In fact, based on planktic foraminiferal records, subtropical biodiversity is predicted to decrease in the near future due to global warming. However, only a few modern planktic foraminifera studies in the subtropical Pacific Ocean have been reported. In this study, we used sediment trap samples from the subtropical Pacific Ocean with a two-week time resolution to examine in detail the seasonal changes in fluxes and assemblage of planktic foraminifera. Foraminiferal fluxes showed large seasonal variations, generally high in winter and low in summer. This was not associated with fluctuations in total fluxes, which were relatively high in summer and autumn. It suggests that foraminiferal fluxes in the subtropics are generally dominated by factors unrelated to total fluxes, such as sea surface temperature and water column stratification.Foraminiferal assemblage composition also showed a large seasonal variation, with each species showing a peak in flux at different times. This might be attributed to the different environmental factors that regulate each species.