日本地球惑星科学連合2019年大会

講演情報

[E] ポスター発表

セッション記号 B (地球生命科学) » B-PT 古生物学・古生態学

[B-PT04] Biomineralization and the Geochemistry of Proxies

2019年5月26日(日) 15:30 〜 17:00 ポスター会場 (幕張メッセ国際展示場 8ホール)

コンビーナ:豊福 高志(国立研究開発法人海洋研究開発機構)、北里 洋(国立大学法人東京海洋大学)、Bijma Jelle(アルフレッドウェゲナー極域海洋研究所)、廣瀬 孝太郎(早稲田大学  大学院創造理工学研究科 地球・環境資源理工学専攻)

[BPT04-P05] Effects on larger benthic foraminiferal shell density under global warming

★Invited Papers

*木下 峻一1黒柳 あずみ2西 弘嗣2佐々木 理2藤田 和彦3鈴木 淳4川幡 穂高5 (1.東北大学大学院理学研究科、2.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、3.琉球大学理学部物質地球科学科、4.独立行政法人産業技術総合研究所地質情報研究部門、5.東京大学 大気海洋研究所)

キーワード:大型底生有孔虫、殻密度、マイクロCT、室内飼育実験、地球温暖化

On the recent ocean environment, due to progresses of global warming and ocean acidification, it is concerned that calcifying organisms will be seriously affected from these environmental changes. Larger benthic foraminifers (LBFs) build calcium carbonate shells. Their carbonate productivity is the third highest rate in coral reef area next to reef corals and calcareous algae. Therefore, it is important to clarify the relationship between ocean environmental changes and the response of LBFs for predicting future ocean environment including carbon cycle. Based upon test diameter and shell weight, previous studies expected how foraminifers react to sea water conditions where they are living. However, in those reports, it is still not clear whether the changing of shell weight is due to changing of shell thickness (shell volume) or shell density, also whether that changing is depending sea water temperature or acidity. Thus, this study was performed for clarifying the relationships between water temperature and LBFs shell parameters with laboratory experiments and means of micro computed tomography (CT).

In this study, we cultured the LBF Sorites orbiculus in filtered sea water until reproduction. Soon after S. orbiculus reproduced, clonal individuals from same mother individual were picked and separated into seven groups. One group was selected as initial stage sample, and other six groups were provided for culture experiments. We cultured each groups under six different temperature conditions (19, 21, 23, 25, 27 and 29 °C). Because clonal specimens were reproduced asexually from same individual, it was expected the genetic factors were kept to a minimum. We used micro CT to investigate mean CT number (proxy of density), shell volume, test diameter and chamber number of every clonal specimen after culturing. The results show the high correlation of mean CT number with temperature in contrast to the correlation of shell volume and temperature. This suggests changing in temperature of sea water causes shell density difference, furthermore, LBFs build the higher density shell in the higher temperature as long as they lives in 19 to 29 C° environment.