BPT03-01

会場:104

時間:5 月 26 日 09:15-09:30

JpGU-EGU 国際セッションの意義と狙い
JpGU-EGU Biogeosciences Joint Session: aims and challenge
北里 洋 1∗KITAZATO, Hiroshi1∗
1
1

独立行政法人海洋研究開発機構
Japan Agency for Marine-Earth Science and Technology

JpGU に地球生命科学セクションが創立されて以来、EGU との国際セッションを行なっている。本セッションは、石灰化する生物をプロキシー生物として、殻に記録された地球化学情報からその生態および海洋環境を読み取ることを目指している。そのために、殻を作る生物の生態や生理、そして地球化学的な特徴を検討するような、地球科学と生物学をまたぐ研究を奨励している。本講演では、プロキシー生物として重要な分類群である有孔虫の多様性とそのプロキシーへの有用性を論ずる。
キーワード: 地球生命科学, 有孔虫, プロキシー, 自然史, 基礎研究
Keywords: Biogeosciences, foraminifera, proxy, natural history, basic

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BPT03-02

会場:104

時間:5 月 26 日 09:30-09:45

浮遊性有孔虫・遺伝子型の季節変動
Seasonal variation in genetic types of a planktonic foraminifer
氏家 由利香 1∗ ; 上田 拓史 2
UJIIE, Yurika1∗ ; UEDA, Hiroshi2
1
1

信州大学・理学部生物科学科, 2 高知大学・総合研究センター海洋生物研究教育施設
Department of Biology, Shinshu University, 2 Usa Marine Biological Institute, Kochi University

Planktonic foraminifers have been employed in paleoceanographic studies due to two major characters: wide geographic
distributions of species and chemical composition of their calcareous shells, which reflect temperature and chemistry of ambient
seawater. Accumulating phylogeographic knowledge, high genetic diversity of planktonic foraminifers has been known today
and these genetically isolated species are distributed in narrower geographic area than we expected. The previous studies reestablished temperature dependences of genetic types according to the pattern of their geographic distributions in many area.
Moreover, genetic differentiation among geographically distant populations examined the role of ocean currents in dispersal ofplanktonic foraminifers. In order to improve the use of planktonic foraminifers as ocean environmental indicators, understanding
ecological characters of genetic types is a crucial issue. In the previous studies for molecular phylogenetic analyses, living
specimens of planktonic foraminifers were collected at each site as occasion arises. The present study therefore collected samples
every month for 1 and half years at same location, the Tosa Bay, where the branch of the Kuroshio Current reaches. We focused on
Globigerinoides ruber , the most commonly used species for paleoceanography, and found this morphospecies during the wholeyears in the study area. Four genetic types are detected throughout our survey, though the frequency of each type varied at eachsampling time. We demonstrate the effect of external environment to productivity of planktonic foraminifers by analyzing therelationship among water-temperature, chlorophyll concentration, and frequency of genetic types. We furthermore test whether
the distance from the main path of the Kuroshio Current is efficiently caused to transport a population of specific genetic type.
These examinations provide us the exact information to address seasonal variation of planktonic foraminifers at genetic-type
level.
キーワード: 時系列試料, 浮遊性有孔虫, 遺伝子型, 生態的特徴
Keywords: time-series collection, planktonic foraminifer, genetic type, ecological feature

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BPT03-03

会場:104

時間:5 月 26 日 09:45-10:00

Cryptic diversity in planktonic foraminifera and the relationship between molecular andmorphological classification
Cryptic diversity in planktonic foraminifera and the relationship between molecular andmorphological classification
WEINER, Agnes1∗ ; KITAZATO, Hiroshi2 ; KUCERA, Michal1
WEINER, Agnes1∗ ; KITAZATO, Hiroshi2 ; KUCERA, Michal1
11

MARUM, University of Bremen, 2 JAMSTECMARUM, University of Bremen, 2 JAMSTEC

Planktonic foraminifera are marine single celled eukaryotes that are found globally in the ocean. They construct calcite shellsthat accumulate in the sediment and are used for micropaleontological studies to reconstruct past climate conditions. Modern
planktonic foraminifera have been classified into about 40 species on the basis of morphological characteristics of their calcite
shell. Molecular investigations however uncovered an unexpectedly high cryptic genetic diversity within these morphospecies,
implying that their biodiversity has been largely underestimated. These cryptic species show distinct biogeographic distribution
patterns and ecological adaptations. Therefore, understanding the extent of genetic diversity within a morphospecies as well as
the ecological adaptations of its cryptic species is highly important in order to enhance the applicability of foraminifera as proxies
in micropaleontological studies. We are applying a single cell approach to survey the extent of cryptic diversity within the SSU
rDNA of individual morphospecies and to examine the biogeography, habitats and ecological adaptations of cryptic species. In
addition, we are trying to establish a connection between genetic diversity and morphological variability of the calcite shells bymorphometric analysis in order to taxonomically revise the morphospecies and to create a connection between living specimens
and the fossil record.

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BPT03-04

会場:104

時間:5 月 26 日 10:00-10:15

採光の機能を持った大型底生有孔虫の棘状突起
A fundamental function of calcareous spine of large benthic foraminifers for lighting
inside石谷 佳之 1∗ ; Cusack Maggie1
ISHITANI, Yoshiyuki1∗ ; CUSACK, Maggie1
1
1

グラスゴー大学地球科学科
School of Geophysical and Earth Science, Glasgow University

Major groups of foraminifers precipitate calcium carbonate and form calcareous shells with unique and complicate structure.
One characteristic structure is a spine, covering the exterior surface of the shells. These shells and spines are though to have afunction for the protection of the cell from predators or for the prop to extend the pseudopodia. However, in other organisms(e.g., land plants), calcareous crystals play a role for increasing light intensity into the photosynthetic tissue more efficiency byscattering light. Our question is what are ecological functions of the shell and spines of calcareous crystals in foraminifers.
Large benthic foraminifers (e.g., Calcarina ) are the dominant species in the tropical reef waters, where is under exposureof strong light with nutrient depletion. They harbor a vast amount of photosynthetic symbionts inside the cell and utilize these
symbionts for uptake recycle-nutrients to survive in the oligotrophic waters. Morphologically, Calcarina have blunt spines, which
help to spread the pseudopodia, extended in a single circle round a central axis. Their pseudopodia attach to the basement, andavoid to be flowed over by tidal wave. However, our knowledge to ecological function of calcareous spines of Calcarina is still
limited. We investigated the crystal orientation of calcareous spines of Calcarina gaudichaudii by using Electron Back Scatter
Diffraction (EBSD) analysis. Calcareous crystals are arranged horizontally to the axis of the spine in the center and graduallyvent to the edge. This orientation of calcareous crystals makes a pathway of light through spines to the interior of the shell.
Our finding suggests that calcareous spines of C. gaudichaudii have ecological function to focus light into the cell and promote
photosynthesis of their harboring symbionts.

キーワード: カルカリナ属, 炭酸塩鉱物, 電子線後方散乱回折法
Keywords: Calcarina, calcareous, Electron Back Scatter Diffraction analysis

1/1BPT03-05

会場:104

時間:5 月 26 日 10:15-10:30

トランスジェニックアコヤガイを用いた貝殻タンパク質の機能解析
Functional analysis of shell proteins using transgenic pearl oysters
趙 然 1∗ ; 遠藤 一佳 1
ZHAO, Ran1∗ ; ENDO, Kazuyoshi111

東京大学 地球惑星科学専攻
Dept of Earth and Planetary Sciences, University of Tokyo

For the study of biomineralization, the mollusc Pinctada fucata is arguably an attractive genetic model system, with its draft
genome sequence having been deciphered recently. It produces two crystallographically different shell layers, including theindustrially important nacreous layer. We are interested in developing knock-out pearl oysters to analyze the functions of shell
matrix proteins, the key players in biomineralization processes, including the unusually acidic protein Aspein. In this study, thewidely used Minos transposon system is applied to generate insertional mutagenesis. The first step in developing transposons as
tools for mutagenesis is to demonstrate their mobile elements function efficiently and stably in the target organism. Therefore,
green fluorescent protein (GFP) is integrated into the transposon to reflect its efficiency.

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BPT03-06

会場:104

時間:5 月 26 日 11:00-11:15

共焦点顕微鏡による大型有孔虫の細胞質形態と小胞内ｐ H の可視化
Morphological observation of cytoplasm with acidic and alkaline vesicles in large foraminifera
cell by confocal imaging
大野 良和 1∗ ; 藤田 和彦 2 ; 豊福 高志 3 ; 中村 崇 1
OHNO, Yoshikazu1∗ ; FUJITA, Kazuhiko2 ; TOYOFUKU, Takashi3 ; NAKAMURA, Takashi1
1

琉球大学理工学研究科, 2 琉球大学理学部物質地球科学科, 3 独立行政法人海洋研究開発機構
Graduate school of Engineering and science, University of Ryukyus, 2 Department of Physics and Earth Sciences, University of
Ryukyus, 3 Institute of Biogeosciences (BioGeos), Japan Agency for Marine-Earth Science and Technology
1

Algal symbiont-bearing large benthic foraminifers are primary and carbonate producers as well as paleoenvironmental indicators in tropical and subtropical reef environments. Despite their importance, their cellular physiology is not well known. In
the present study, we have developed methods to observe in vivo images of a living symbiotic porcelaneous large foraminifer,
Amphisorus kudakajimensis. The Nikon A1 confocal laser scanning microscope with Calcein-AM was used as a fluorescent indicator for visualizing the morphology and streaming of cytoplasm in living A. kudakajimensis. The observations indicated thatthe cytoplasmic density decreased and reticulopodia were formed at the aperture in the marginal part of intrashell cytoplasm. We
also observed vesicles with elevated pH (pH 9.0) and lowered pH (pH 6.0) in reticulopodia-like cytoplasms using a pH-sensitive
probe molecule, 8-hydroxypyrene-1,3,6-trisulfonic acid (HPTS). The present study demonstrates the use of confocal microscopy
in studying cytoplasmic dynamics and the initial calcification processes such as seawater endocytosis and alkalization of seawatervacuoles.
キーワード: 大型有孔虫, 共焦点顕微鏡, 生体観察, ｐ H, 石灰化
Keywords: Large foraminifera, Confocal imaging, Live imaging, pH, Calcification

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BPT03-07

会場:104

時間:5 月 26 日 11:15-11:30

Calcification mechanisms in foraminifera and proxy incorporation
Calcification mechanisms in foraminifera and proxy incorporation
Bijma Jelle1∗ ; Nehrke Gernot1 ; Raitsch Markus1 ; de Nooijer Lennart2 ; Funcke Antje1 ; Keul Nina3
BIJMA, Jelle1∗ ; NEHRKE, Gernot1 ; RAITSCH, Markus1 ; DE NOOIJER, Lennart2 ; FUNCKE, Antje1 ;KEUL, Nina3
1

Marine Biogeosciences, Alfred Wegener Institute, 2 Marine Geology, Royal NIOZ, 3 Biology and Paleo Environment, LamontDoherty Earth Observatory
1
Marine Biogeosciences, Alfred Wegener Institute, 2 Marine Geology, Royal NIOZ, 3 Biology and Paleo Environment, LamontDoherty Earth Observatory
Calcifying organisms, such as pteropods, bivalves, corals and foraminifera provide a rich resource for pale-oceanographers and?climatologists because their geochemical make-up (proxies) can be used to reconstruct past ocean history and evolution during
and after natural carbon perturbations. However, it has been shown for all geochemical proxies that the main assumption of only
one environmental variable controlling a target proxy is too simple. Empirical calibrations introduce a lot of uncertainty because
the mechanisms of proxy incorporation are not well understood. The major problem is that the calcification mechanisms are stilla black box. In this presentation I will review our current understanding of calcification and proxy incorporation in foraminifera,
specifically with respect to the impact of carbonate chemistry and the new opportunities arising from this.
キーワード: 石灰化, 有孔虫, 古環境指標
Keywords: Calcification, proxy1/1

BPT03-08

会場:104

時間:5 月 26 日 11:30-11:54

Minor element partitioning and mineralogy in limpets from a CO2 vent site
Minor element partitioning and mineralogy in limpets from a CO2 vent site
Nehrke Gernot1∗ ; LANGER Gerald2 ; SADEKOV Aleksey2 ; BAGGINI Cecilia3 ; RODOLFO-METALPA Riccardo4 ;HALL-SPENCER Jason3 ; Bijma Jelle1 ; ELDERFIELD Henry2
NEHRKE, Gernot1∗ ; LANGER, Gerald2 ; SADEKOV, Aleksey2 ; BAGGINI, Cecilia3 ;RODOLFO-METALPA, Riccardo4 ; HALL-SPENCER, Jason3 ; BIJMA, Jelle1 ; ELDERFIELD, Henry2
1

Biogeosciences, Alfred-Wegener-Institut, 2 University of Cambridge, 3 School of Marine Science and Engineering, Universityof Plymouth, 4 CoReUs, IRD, Centre IRD de Noumea
1
Biogeosciences, Alfred-Wegener-Institut, 2 University of Cambridge, 3 School of Marine Science and Engineering, Universityof Plymouth, 4 CoReUs, IRD, Centre IRD de Noumea
Specimens of the patellogastropod limpet Patella caerulea were collected within and outside a CO2 vent site at Ischia, Italy.
The shells were sectioned transversally and scanned for polymorph distribution by means of confocal Raman microscopy. Minor element to calcium ratios were measured using laser-ablation-inductively-coupledplasma-mass-spectroscopy (LA-ICPMS).
Mg/Ca, Sr/Ca, and Li/Ca ratios were determined in calcitic as well as aragonitic parts of the shells. This approach allows forinvestigating the effects of the polymorph and the seawater carbonate chemistry on minor element partitioning separately.
キーワード: calcification, proxy, CO2, mineralogy, patellogastropod limpet
Keywords: calcification, proxy, CO2, mineralogy, patellogastropod limpet

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BPT03-09

会場:104

時間:5 月 26 日 11:54-12:09

底生有孔虫の石灰化過程におけるプロトン、炭素、カルシウム輸送の数理分析
Mathematical analysis of proton, carbon, and calcium transport during calcification process of benthic foraminifera
山本 美希 1∗ ; 豊福 高志 1 ; 阪口 秀 1 ; デ ヌーエヘル レナート 2
MATSUO, Miki Y.1∗ ; TOYOFUKU, Takashi1 ; SAKAGUCHI, Hide1 ; DE NOOIJER, Lennart J.2
11

海洋研究開発機構, 2 ユトレヒト大学
Japan Agency for Marine-Earth Science and Technology, 2 Utrecht University

海洋性単細胞生物である有孔虫は、今日の海洋の炭酸カルシウムのおよそ 50%を生成しており、海洋における炭素サ
イクルの重要な部分を担っている。しかしながらその石灰化過程がどのようなメカニズムで進行し、どのように環境を変えているのかは未だ理解されていない。
今回我々は、有孔虫の石灰化過程を理解するために行った pH 分析の結果を報告する。まず pH を可視化することにより、石灰化過程にともなって有孔虫のまわりの pH が急速に低下することが確かめられた。これは有孔虫が石灰化時にプロトンを能動的に外界に輸送していることを意味している。次に可視化した pH 分布からプロトンの流束を見積もり、その流束と釣り合うような内部へのカルシウム輸送を仮定して、そのカルシウムの流入総量と新しいチャンバーを作るために必要な炭酸カルシウム量と比較した。これら結果を用いて、プロトンとカルシウムとの交換が石灰化過程に重要な役割を果たしていることを提唱する。

キーワード: 底生有孔虫, 石灰化, プロトン輸送, 数理分析
Keywords: benthic foraminifera, calcification, proton transport, mathematical analysis

1/1BPT03-10

会場:104

時間:5 月 26 日 12:09-12:24

浮遊性有孔虫光共生系の栄養機構の理解にむけた飼育実験からのアプローチ
An experimental approach to understand trophic interaction of photosymbiosis in planktic
foraminifers
高木 悠花 1∗ ; 木元 克典 2 ; 藤木 徹一 2 ; 平野 弘道 3
TAKAGI, Haruka1∗ ; KIMOTO, Katsunori2 ; FUJIKI, Tetsuichi2 ; HIRANO, Hiromichi3
1

早稲田大学・院・創造理工, 2 海洋研究開発機構, 3 早稲田大学・教育・地球科学
CSE Grad. School, Waseda University, 2 Japan Agency for Marine-Earth Science and Technology, 3 Dep. Earth Sciences, Sch.
Education, Waseda University

1

Planktic foraminifers are marine heterotrophic protists. Of about 50 species of modern planktic foraminifers, about 10 species
that especially dominate in warm and low-nutrient surface water harbor autotrophic algae as endosymbionts (photosymbiosis).
It is generally considered that foraminifers benefit from photosynthates of symbionts, and in return, they provide nutritious environment for symbionts to live. At the same time, however, the host’s degree of dependence on symbionts is still enigmatic. Thisis because growth of the host primarily depends on food (prey) availability. In this context, a common assumption that photosymbiosis is an advantageous ecology for host foraminifers to live in oligotrophic oceans still has room to discuss. To understandtrophic interaction between host and symbionts, we conducted culture experiments and analyzed vitality of host-symbiont consortia under controlled nutrient conditions.
We cultured dinoflagellate-bearing species Globigerinoides sacculifer for two weeks. Assuming the two sources of nutrientsfor symbionts, i.e., from the host’s metabolites and from the ambient seawater, we controlled feeding regime (fed Artemia every other day or unfed) and nutrient concentration of culture media (0.22-µm filtered seawater [SW] or nutrients-added filteredseawater [NSW]). Four experimental groups are set; (a) fed and SW, (b) unfed and SW, (c) fed and NSW, and (d) unfed and
NSW. Nutrient concentrations of SW and NSW were respectively 0.2 and 16 µmol L−1 of NO3 +NO2 , and 0.07 and 1.0 µmol
L−1 of PO4 . Temperature was set to 26.5-27.5 ℃. Photosynthetic active radiation was set to 170-220 µmol quanta m−2 s−1 ,and its light/dark cycle was 14/10 hours. Test growth of the host, chlorophyll content, and photo-physiology of the symbionts
were used as criteria of their vitality. We measured maximum test length of host foraminifers and chlorophyll fluorescence ofindividual host-symbiont consortium during the culture period almost every day. For fluorometric analysis, we used fast repetition rate (FRR) fluorometry. From FRR measurement, F m (an index of chlorophyll content), and F v /F m (an index of potential
photosynthetic activity) were obtained and analyzed for each individual consortium.
During the culture period, foraminifers grew and formed new chambers in the fed groups (a, c). On the contrary, specimens
in the unfed groups (b, d) gradually decreased their cytoplasm volume, and in accordance with the decrease they often shedchambers one by one. The chlorophyll content, thus the biomass of symbionts per foraminifer, tended to increase in the fed
groups (a, c), whereas it decreased or kept nearly constant in the unfed groups (b, d). Despite the apparent diminishment of
the unfed groups, F v /F m was significantly higher in the unfed groups (b, d) than that in the fed groups (a, c). It indicates thatsymbionts in starved foraminifers photosynthesized more actively. Nutrient concentration in the culture media (SW or NSW) did
not necessarily affect on F v /F m .
Considering the fact that foraminifers maintained their life and symbionts were capable of photosynthesis in starved condition,
it can be said that foraminifers have survived only by photosynthates derived from the symbionts or digesting the symbionts
themselves for about two weeks of the culture period. If this relationship is true in natural environment, photosymbiotic interaction should help foraminifers to survive for certain duration even if they cannot capture any prey. This should be an advantage
for them to live in low-nutrient and well-lit environment.
キーワード: 浮遊性有孔虫, 光共生, 栄養塩, FRRF, 飼育
Keywords: planktic foraminifers, photosymbiosis, nutrients, FRRF, culture

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BPT03-11

会場:104

時間:5 月 26 日 12:24-12:39

沖ノ鳥島シラナミガイ殻に記録された 2005 年巨大台風の痕跡
Strong typhoon in 2005 recorded in the shell growth lines and geochemical signals of T.
maxima from Okinotori Island
駒越 太郎 1∗ ; 渡邊 剛 1 ; 宮地 鼓 2 ; 白井 厚太朗 3 ; 山崎 敦子 3
KOMAGOE, Taro1∗ ; WATANABE, Tsuyoshi1 ; MIYAJI, Tsuzumi2 ; SHIRAI, Kotaro3 ; YAMAZAKI, Atsuko3
1

北海道大学理学院自然史科学専攻, 2 苫小牧市美術博物館, 3 東京大学大気海洋研究所
Department of Natural History, Graduate School of Science, Hokkaido Univ., Sapporo, Japan, 2 Tomakomai City Museum,Tomakomai, Japan, 3 Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Japan1

The giant clam (Tridacnidae ) widely distributes over the coral reefs in Indo- Pacific oceans and forms the largest shells inbivalves. The giant clam has symbiotic algae, facilitating fast growth rate and forming daily shell growth patterns. By measuring
and counting the daily growth lines, we can know exactly when the daily growth lines were deposited. This growth pattern analysis is useful for reconstruction of the past environments at daily resolution. The aim of this study was to validate whether the shellof the giant clam (Tridacna maxima ) in Okinotori Island, the southern edge island in Japan, could record daily environmental
events such as typhoons.
The shell samples were collected alive in Okinotori Island on 5th Jun 2006. The shells were cut into two slices along the maximum growth axis. The number and interval width of microgrowth lines were measured under a digital microscope (KYENCE
VHX-2000). Sub-sampling for oxygen stable isotope measurements were performed along the growth direction on another sliceof the shell by using dental drill. The powder samples were introduced to carbonate preparation device (Kiel Device Ⅳ), andthe produced CO2 was analyzed by a stable isotope ratio mass spectrometer(Thermo Scientific MAT253). Stable oxygen isotope
ratios (δ 18 O) were compared with sea surface temperature (SST) and maxima values were assigned the lowest SST in February.
The correspondence between reconstructed SST and daily observed SST indicated that the microgrowth lines were formed daily
basis. Growth disturbances were observed as v-shaped breaks in the shell outer layers. The high δ 18 O peaks corresponded withthese growth disturbances suggested that this specimen recorded the strong typhoon in Okinotori Island on 3th September 2005.
Trace element analysis using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) (Agilent 7700) with
100µm and 30µm spots (Mg, Ca, Mn, Sr, Ba) revealed that the specimen has Ba/Ca positive peaks as an after-signature of strong
typhoons. Moreover, the significant positive peaks observed in Ba/Ca profile suggested the upwelling events due to typhoons in
Okinotori Island.
These results indicated that sclerochronological and geochemical record in giant clam shells could be useful for reconstructionof past typhoon events.
キーワード: シャコガイ, 酸素同位体, 炭素同位体, 微量元素, 成長縞
Keywords: Giant clam, Oxygen isotope, Carbon isotope, Trace elements, Growth line

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BPT03-12

会場:104

時間:5 月 26 日 14:15-14:40

近年の北西太平洋の海洋酸性化がハマサンゴの石灰化に与える影響
Effects of recent ocean acidification in the western North Pacific on Porites coral calcification
窪田 薫 1∗ ; 横山 祐典 1 ; 石川 剛志 2 ; 鈴木 淳 3 ; 石井 雅男 4
KUBOTA, Kaoru1∗ ; YOKOYAMA, Yusuke1 ; ISHIKAWA, Tsuyoshi2 ; SUZUKI, Atsushi3 ; ISHII, Masao41

東京大学 大気海洋研究所, 2 海洋研究開発機構, 3 産業技術総合研究所, 4 気象庁 気象研究所
Atmosphere and Ocean Research Institute, The University of Tokyo, 2 Japan Agency for Marine-Earth Science and Technology,3
National Institute of Advanced Industrial Science and Technology, 4 Meteorological Research Institute, Japan Meteorological
Agency1

人間活動の結果大気へと放出された二酸化炭素の約３分の１は海洋表層水によって吸収されたと考えられている。その結果、海水 pH は例にない速さで低下しており（海洋酸性化）、産業革命以降、すでに 0.1 低下したと考えられている。
海水 pH の低下は炭酸塩飽和度を低下させるため、造礁サンゴに対して重大な影響をもたらすと考えられている。これまで、海洋酸性化が造礁サンゴに与える影響の評価は一般に飼育実験を通じて行われてきており、野外において影響を評価した研究はほとんどない。環境変化に対してサンゴそしてサンゴ礁生態系がどのように適応するか、或いは影響を被るかをより良く理解するためにも野外観測は必要不可欠である。そこで本研究では、北西太平洋・小笠原諸島父島で得られた塊状ハマサンゴに対して、表面電離型質量分析器を用いて過去 100 年間のホウ素同位体比（δ 11 B）の分析を行った。測定結果は、1960 年以降のホウ素同位体比が顕著に低下していること (-0.17 ± 0.07 ‰/decade)、すなわち石灰化流
体の pH が低下していることを示唆している。さらに、ハマサンゴの飼育実験の予想よりも早く石灰化流体の pH が低下していること（感度が高い）も分かった。このことは、石灰化流体の pH の上方調整機構にもかかわらず、アラゴナイト
飽和度が予想よりも早く低下する可能性を示唆するものである（2050 年頃に海水の pH が 8.0 程度になった時には石灰化流体の pH は 8.3 程度）。従って、海洋酸性化は、温暖化に代表される種々の環境ストレスに既に晒されている造礁サンゴに対してさらなる悪影響を既にもたらしている可能性が高いと考えられる。
キーワード: ホウ素, サンゴ, ハマサンゴ, 海洋酸性化, 石灰化
Keywords: boron, coral, Porites, ocean acidification, calcification

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BPT03-13

会場:104

時間:5 月 26 日 14:40-14:55

Proton Management of Foraminiferal Calcification
Proton Management of Foraminiferal Calcification
TOYOFUKU, Takashi1∗ ; DE NOOIJER, Lennart jan2 ; FUJITA, Kazuhiko4 ; SHIRAISHI, Fumito3 ;REICHART, Gert-jan2 ; KITAZATO, Hiroshi1
TOYOFUKU, Takashi1∗ ; DE NOOIJER, Lennart jan2 ; FUJITA, Kazuhiko4 ; SHIRAISHI, Fumito3 ;REICHART, Gert-jan2 ; KITAZATO, Hiroshi1
1
1

JAMSTEC, 2 NIOZ, 3 Hiroshima University, 4 Universoty of Ryukyus, 5 Utrecht University
JAMSTEC, 2 NIOZ, 3 Hiroshima University, 4 Universoty of Ryukyus, 5 Utrecht University

Marine calcification plays an important role in the global carbon cycle. Currently, approximately half of all carbon buried in theseafloor is the result of biogenic calcium carbonate production. Perforate foraminifera are a prime example of marine carbonate
producers and responsible for a large portion of today’s production. The physiological processes involved in calcification, however, are still unclear. Here we present some results on the intra- and extracellular pH changes in benthic perforate foraminifera
during calcification. These observations allow for calculating the budgets of ion fluxes that are taken up and removed from thecalcification space, which are placed in the context of previously obtained results and published calcification models to constructa unifying model for perforate foraminiferal calcification. This model also accounts for general patterns in observed fractionation
factors of various elements.
キーワード: foraminifera
Keywords: foraminifera

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会場:104

時間:5 月 26 日 14:55-15:10

無機的環境下における炭酸カルシウム多形の形成過程とその前駆物質
Inorganic precipitation mechanism of calcium carbonate polymorphs and their precursors
川野 潤 1∗KAWANO, Jun1∗
11

北海道大学 創成研究機構
Creative Research Institution, Hokkaido University

Calcium carbonate, CaCO3 , occurs in six different forms: three crystalline polymorphs (calcite, aragonite, and vaterite), twohydrate phases, and amorphous calcium carbonate (ACC). These polymorphs are important both in life and material sciences,
especially the occurrence of CaCO3 in living organisms has received considerable attention. As a basis for understanding biomineralization, inorganic precipitation mechamism of these polymorphs has been extensively investigated for over a hundred years.
Recently, crystallization pathway through non-classical mechanism such as stable prenucletaion cluster aggregation has been
proposed, which give a new picture of the early stages of calcium carbonate growth. However our knowledge of formation
process of CaCO3 , especially that of the mechanism of polymorph selection, is far from complete.
We have investigated experimentally and theoretically the metastable formation of CaCO3 polymorphs and their precursors.
In particular, the effect of Mg2+ on the nucleation and growth of CaCO3 polymorphs has been focused and the quantum chemical calculations of Mg-containing CaCO3 surfaces and clusters appearing in the early stages of CaCO3 formation have been
performed. As a result, Mg2+ substituted for Ca2+ affects the structure of surfaces and clusters, and may have significant effecton the polymorph selection of CaCO3 . In this presentation, we will report our results in detail based on the recent progress inthis field.
Keywords: calcium carbonate, metastable phase, precursor

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BPT03-15

会場:104

時間:5 月 26 日 15:10-15:35

生体由来および生体模倣カルサイト結晶におけるメソテクスチャー構造
Mesoscopic textures of biogenic and biomimetic calcite crystals
今井 宏明 1∗ ; 宮島 諒一 1 ; 緒明 佑哉 1 ; 小暮 敏博 2
IMAI, Hiroaki1∗ ; MIYAJIMA, Ryoichi1 ; OAKI, Yuya1 ; KOGURE, Toshihiro2
1
1

慶應義塾大学理工学部, 2 東京大学大学院理学系研究科
Faculty of Science and Technology, Keio University, 2 Graduate School of Science, The university of Tokyo

The mesoscale granular textures having a single crystalline feature are generally observed on the continuous body of various
biogenic and biomimetic calcite crystals. The distribution of the organic phase and lattice strain in the textured crystals vary withorganism species or the growth conditions. The prismatic layer of a fan mussel, A. pectinata, exhibits a relatively homogeneous,
low-strain texture consisting of the nanoscale grains with discrete organic inclusions; the prism structure of a pearl oyster, P.
fucata, and an avian eggshell have a high-strain granular texture with localized organic phases. A variety of the mesoscopic
textures similar to the biogenic calcite crystals are artificially produced in a supersaturated solution containing specific organic
molecules. The high-strain textures were produced through mesoscopic dendritic growth of calcite by physical impedance of arigid gel matrix and subsequent thickening of the branches. Continuous growth of the crystal involving nanoscale segregation ofsoluble polymers would result in the formation of the low-strain body having mesoscopic textures. The chemical durability of
the low-strain biogenic and biomimetic textured calcites are enhanced by the combination of the inorganic crystal and the organic
molecules.
Keywords: Biomineral, Calcium carboate, Mesocrystal

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