R/V Yokosuka – Shinkai 6500 YK06

R/V Yokosuka – Shinkai 6500
YK06-11 Cruise in Palau Trench
“PalaDiCe” Expedition
August 14 – 25, 2006
CRUISE REPORT
CONTENTS
1. Introduction
2. Participants on board
2-1. Scientist
2-2. Crew
3. Proposal
4. Dive Reports
4-1.
Dive#969: A complete cross sectional overview of a huge sunken paleo
coral reef at the Palau Trench forearc (Kantaro Fujioka)
4-2.
Dive#970: Abundance, biodiversity and feeding ecology of deep-sea
benthic foraminifera at abyssal depth: reference site for limestone fauna (Hiroshi
Kitazato)
4-3.
Dive#971: A complete cross sectional overview of a huge sunken paleo
coral reef at the Palau Trench forearc -2- (Hideki Wada)
4-4.
Dive#972: Abundance, biodiversity and feeding ecology of deep-sea
benthic foraminifera at abyssal depth: reference site for limestone fauna -2(Kazumasa Oguri)
4-5.
Dive logs
4-6.
List of event sites (in the separated folder “4-6_EventSites”)
4-7.
Maps of each dive (in the separated folder “4-7_MapsofEachDive”)
5. Methods, Results, and future studies for individual study
5-1.
Water samples
5-2.
In situ experiments
Appendix
1. List of Samples (an original file exist in the folder)
1-1.
Water
1-2.
Sediments
1-3.
Rocks
2. List of Videotapes
3. Photographs of payload at each dive
(original pictures exist in the “Appendix_3_” folder)
4. Topography and Track chart
(original files exist in the “Appendix_4_”folder)
5. CTDO data
(pdf files in the “Appendix_CTDO_data)
1. Introduction
Calcium Carbonate Compensation Depth (CCCD) is a depth where calcium
contents of bottom sediment is zero below the depth.
boundary for calcareous benthic organisms.
The depth should be a critical
Because, any of calcium carbonate tests
do not remain in the sediment below the depth.
Organisms that are precipitating
skeletal carbonates either exo- or endo-bodies can survive below the CCCD by secreting
calcium carbonate against dissolution. Of course, the skeletons dissolve instantaneously
after death. These environments should be a stressful for the skeletal organisms.
Limestone are cropped out in the depth of 6500 m at landward slope of the Palau
Trench (Fujioka and Kitazato, 1994).
Muddy sediment covered on limestone is rich in
calcium carbonate, in particular to tests of planktonic foraminifera, even though the
depth is 2000m below the CCD.
Several species of calcareous benthic foraminifera
also dwell in the sediment (Kitazato and Fujioka, 1996).
Our purpose to have a dive cruise is to elucidate why limestone cropped out at
6500m deep and what kind of benthic organisms live in sediment on limestone.
Multidisciplinary researches among geology, geochemistry and biology have been
carried out during the cruise YK06-11. This dive cruise is partly supported by the
Grant-in-Aid from Japan Society of the Promotion of Science, Fundamental Research A
to H.K.
Cruise Coordinator for the cruise YK06-11
Hiroshi Kitazato
(Institute for Research on Earth Evolution,
Japan Agency for Marine-Earth Science and Technology, Japan)
2. Participants on board
2-1. Scientists
北里 洋
独立行政法人海洋研究開発機構
地球内部変動研究センター 地球古環境変動プログラム
PD
Hiroshi KITAZATO (Program Director)
Research Program for Paleoenvironment
Institute for Research on Earth Evolution (IFREE)
Japan Agency for Marine-Earth Science and Technology (JAMSTEC)
藤岡 換太郎
独立行政法人海洋研究開発機構
地球内部変動研究センター プレート挙動解析プログラム
特任研究員
Kantaro FUJIOKA (Senior Scientist)
Research Program for Plate Dynamics
Institute for Research on Earth Evolution (IFREE)
Japan Agency for Marine-Earth Science and Technology (JAMSTEC)
和田 秀樹
静岡大学 理学部 教授
Hideki WADA (Professor)
Institute of Geosciences
Faculty of Science
Shizuoka University
小栗 一将
独立行政法人海洋研究開発機構
地球内部変動研究センター 地球古環境変動プログラム
研究員
Kazumasa OGURI (Researcher)
Research Program for Paleoenvironment
Institute for Research on Earth Evolution (IFREE)
Japan Agency for Marine-Earth Science and Technology (JAMSTEC)
野牧 秀隆
独立行政法人海洋研究開発機構
地球内部変動研究センター 地球古環境変動プログラム
PD 研究員
Hidetaka NOMAKI (Post-Doctoral Researcher)
Research Program for Paleoenvironment
Institute for Research on Earth Evolution (IFREE)
Japan Agency for Marine-Earth Science and Technology (JAMSTEC)
岩崎 藍子
東京大学大学院新領域創生科学研究科 修士課程 1 年
Aiko IWASAKI (Master course student)
Institute of Environmental Studies
Graduate School of Frontier Science
The University of Tokyo
岡田 聡
日本海洋事業株式会社 海洋科学部
Satoshi OKADA
Nippon Marine Enterprises ,Ltd
2-2. Crew members
No
職 名
Position
氏 名
１
船 長
Captain
齋藤 房夫
SAITO
FUSAO
2
一航士
Chief Off
青木 高文
AOKI
TAKAFUMI
3
二航士
2nd Off
前田 勇雄
MAEDA
ISAO
4
三航士
3rd Off
高尾
TAKAO
JUN
5
機関長
Chief Eng
梶西喜代徳
KAJINISHI
KIYONORI
6
一機士
1st Eng
梶原 正博
KAJIHARA
MASAHIRO
7
二機士
2nd Eng
平塚 義信
HIRATSUKA
YOSHINOBU
8
三機士
3rd Eng
橋本 豊
HASHIMOTO
YUTAKA
9
電子長
Chief Electronics Operator
WATASE
SATOSHI
10
二電士
2nd Electronics Operator
北村 勝利
KITAMURA
KATSUTOSHI
11
甲板長
Boat Swain
中村
NAKAMURA
KINGO
12
甲板手
Able Seaman
13
甲板手
Able Seaman
角口 国治
KADOGUCHI
KUNIHARU
14
甲板手
Able Seaman
山本 修一
YAMAMOTO
SHUICHI
15
甲板手
Able Seaman
大端 正則
OHATA
MASANORI
16
甲板手
Able Seaman
吉野 勇希
YOSHINO
YUKI
17
甲板員
Sailor
高橋 英樹
TAKAHASHI
HIDEKI
18
操機長
No.1 Oiler
八幡 喜好
YAHATA
KIYOSHI
19
操機手
Oiler
MIURA
KOZO
20
操機手
Oiler
大石 洋之
OISHI
HIROYUKI
21
機関員
Assistant Oiler
田中 佐幸
TANAKA
SAKOH
22
機関員
Assistant Oiler
田中 将貴
TANAKA
MASAKI
23
司厨長
Chief Steward
宮内 武志
MIYAUCHI
TAKESHI
24
司厨手
Steward
田中 信介
TANAKA
SHINSUKE
25
司厨手
Steward
高津 忠幸
TAKATSU
TADAYUKI
26
司厨員
Porter
阿部 崇裕
ABE
TAKAHIRO
27
司厨員
Porter
潜技長
Operetion Maneger
渡瀬
淳
諭
金吾
Family
八頭後 浩三 YATOGO
三浦
浩三
富宇加 誠之 TOMIUKA
Given
KOZO
SATOSHI
28
29
今井 義司
IMAI
YOSHIJI
30 一等潜技士
Assistant Operation Maneger
櫻井 利明
SAKURAI
TOSHIAKI
31 一等潜技士
1st Submersible staff
佐々木義高
SASAKI
YOSHITAKA
32 一等潜技士
1st Submersible staff
牧 哲司
MAKI
TETSUJI
33 一等潜技士
1st Submersible staff
川間 格
KAWAMA
ITARU
34 一等潜技士
1st Submersible staff
大野 芳生
ONO
YOSHINARI
35 二等潜技士
2nd Submersible staff
小椋 徹也
KOMUKU
TETSUYA
36 二等潜技士
2nd Submersible staff
松本 恵太
MATSUMOTO KEITA
37 三等潜技士
3rd Submersible staff
植木 博文
UEKI
HIROFUMI
38 三等潜技士
3rd Submersible staff
齋藤 文誉
SAITO
FUMITAKA
39 三等潜技士
3rd Submersible staff
大西 琢磨
ONISHI
TAKUMA
3. Proposal
Scientific background and objectives of the dive cruise
Calcium carbonate (CaCO3) is soluble in seawater.
However, the solubility
changes in relation to specific environmental conditions, such as carbonate saturation
levels, hydraulic pressures and temperatures of ambient seawater.
In the western
Equatorial Pacific, dissolution threshold for calcium carbonate situates in between 4100
and 4500m.
We call the limit as CCD (Calcium carbonate Compensation Depth).
Theoretically, calcium carbonate contents in sediment are zero percent below the CCD.
The CCD depths change in proportion to the balance between supply of calcium
carbonate and dissolution rates.
than those of the Pacific.
For instance, CCD of the Atlantic is 1000m deeper
Because both carbonate contents in deep-sea water and
surface calcium carbonate production by planktic organisms are much higher at the
Atlantic Ocean than the Pacific.
Calcareous planktic organisms have appeared on the sea during the middle of the
Mesozoic Era.
Because calcareous components in marine snow particles were
increased drastically at the middle Mesozoic, CCD became deep in comparison to the
earlier Mesozoic.
Calcareous benthic foraminifers have become a major group among
deep-sea benthic communities since then. For examining this scenario, we need to
check calcareous benthic faunas at modern analogous environmental settings.
Fortunately, we found large limestone blocks in the landward slope with 6500m deep at
the Palau Trench during Shinkai 6500 dives #190 and #293 (Figure 1. Fujioka and
Kitazato, 1994; Kitazato and Fujioka, 1996). The limestone blocks are distributed in
2000m deeper than average CCD at the western equatorial Pacific.
covers thinly on the limestone blocks.
Deep-sea sediment
Calcareous benthic foraminifera (single-celled
organisms) richly furnish in the sediments together with common soft-shelled and
agglutinated benthic foraminifera.
in the world.
This should be the deepest calcareous benthic fauna
It also should be modern analogue of the mid-Mesozoic marine
revolution as stated above.
We have two research targets for the limestone blocks at the Palau trench during
Shinkai 6500 dives.
1. Origin of limestone blocks:
depth?
Why and how do these limestone blocks exist at the
When and where do limestone form?
How do these limestones transport
and settle at the depth? What kinds of relation do exist between tectonic evolution of
the Palau arc-trench systems and limestone blocks?
For solving these series of
questions, we try to collect limestone block samples from the outcrops in the Palau
Trench.
We plan to investigate geological, geochemical and paleontological
analyses for limestone blocks.
During the night time, we plan to carry out
underwater topographic survey at slope areas between trench and Palau islands. We
expect that large escarpments may exist at shallower slope areas. Limestone blocks
may fall down from these escarpments with debris flow.
2. Deepest calcareous foraminiferal fauna in the world:
What kinds of foraminiferal
species do occupy the fauna in the sediments that cover on limestone blocks?
Where are calcareous benthic organisms originate from?
For investigating to solve
these questions, we plan to collect push core samples, dredge samples from the
sediments that are covered on limestone blocks.
research with push core samples.
We plan to conduct taxonomic
Using taxonomic data, we try to elucidate faunal
composition of sediment dwelling organisms.
We try to extract DNA from deep-sea
benthic foraminifera for discussing about the origin of limestone fauna. During the
dives, we also plan to collect water samples for measuring calcium concentration at
different heights from the sea floor.
These data should be useful for calculating
dissolution flux of calcite from limestone blocks to the bottom water. In addition to
series of dives for limestone blocks, we plan to dive at similar depths of outer slope
of the Palau Trench on the Caroline Plate for comparing faunal composition of
foraminifera between sediments on limestone blocks and those from pelagic
sediments.
In total, four dives will be planned, two dives at limestone block area and two
dives at outer seaward slope of the Palau Trench.
4. Dive reports
4-1. Dive#969
Aug. 21 ‘06
A complete cross sectional overview of a huge sunken paleo coral reef at the Palau
Trench forearc
Kantaro Fujioka (JAMSTEC/IFREE)
4-1-1. Objectives of the dive
In the Palau Trench landward slope at water depth of 6500 m, a large
limestone block was found by Shinkai 6500 dive #190 by Fujioka, 1993 and several
dives (#292, 293, 343, 344, 345) were followed successfully (Fujioka et al., 1993,
Fujioka et al., 1995;1996). Results were two major things; A huge limestone block may
be transported from the land, Palau Island Arc and the landward lower slope consists of
serpentinites like Mariana forearc.
Origin and mechanism of the transportation of huge limestone are still unknown
and characterization of serpentinites was not succeeded. Therefore in this cruise we plan
to elucidate the former problem with special emphasis to bio-geochemical aspect.
The main objectives of this dive are;
(1) To make a topographic and geological cross sectional overview of the Palau
limestone block from east to west parallel to the dive track of # 344 dive, 1996,
(2) To take water samples just on the surface of the limestone block, 0.5m, 1m, 5m and
10m above the limestone and seawater contact with temperature measurement,
(3) To sample limestones, and other rocks such as ultramafic and sedimentary rocks
from various depths for reconstruction and make clear the history of forearc formation
in relation to the lower crust and upper mantle structure,
(4) To sample sediments by MBARI and push corers at various depths for the
microbiological and chemical analyses.
(5) To deploy the special type of MBARI corer for In-situ cultivation of benthic
foraminifers.
4-1-2. Dive site
Palau Trench forearc slope at the same position of event 2 site as dive #293, 6º
20.055’, 133º 57.103’E. Landing at 6500 m and move to 300° direction as shallow as
possible to observe, measure and sample various kind of rocks, sediments and water
existed.
4-1-3. Strategy of dive #969
To best meet the objectives of the dive, the following dive strategy is
proposed at various stops:
(1) First, to land the site near the Black Band of the limestone blocks which lies about
6500m water depth to recognize the exact position.
(2) If we find the suitable site, take water sample just on the limetone body, 0.5m, 1m,
5m and 10m above the body by means both of Pump sampler and Niskin-type water
sampler.
Landing on the limestone body to take Niskin-type water sample first and 3 pump
samples, next, 3 pump samples at 0.5 m above the bottom, and Niskin and 2 pump
samples at 1 m above the bottom, then to take the Niskin-type water samples at 5 m,
and 10 m above the bottom with temperature measurement.
(3) Then we move to thinly covered sediment surface of the limestone body to take push
core sample in order to check the sediment thickness then take 9 MBARI core
samples and deploy 2 special MBARI core for the in situ cultivation and fixation of
foraminifers. Finally we deploy a marker on this site for the recovery of the
cultivation system 2 days later during dive #971 by H.Wada. After taking all the
cores we try to take surface sediments by “Chiritori” sampler.
(4) We move to the Black Band site after accomplishment three missions above to take
push core sample exactly from BB and limestones and other rocks if we encounter.
(5) We move toward shallower part to take samples and observe the distribution of
limestone body.
(6) Continuous video records (three videos, one fixed, one movable, one inside hull 8
mm) and still camera photographs of the Palau forearc will be taken in order to help
elucidate the geological cross sectional map.
4-1-4. Pay loads:
(1) Niskin-type water sampler x 4, (2) Gamo-type pump sampler x 8 bottles with
temperature probe, (3) 9 MBARI type corers in addition to two special equipment for
in-situ cultivation system and special corer with two syringe for in-situ fixation, (4) 3
Push corers, (5) Scoop (Chiritori sampler) for taking pebbles, (6) 8 mm Video camera
(inside pressure hull).
4-1-5. Co-workers of onboard and shore based studies related with this dive:
Topography: H.Kitazato, and S. Okada
Geology: H.Kitazato (JAMSTEC), H.Wada (Shizuoka Univ), K. Oguri and H.Nomaki
(JAMSTEC)
Water sample: H.Kitazato (JAMSTEC), H.Wada (Shizuoka Univ), K.Oguri and
H.Nomaki, (JAMSTEC), and A.Iwasaki (Univ of Tokyo)
Sediments: H.Kitazato (JAMSTEC), H.Wada (Shizuoka Univ), K.Oguri and H.Nomaki,
(JAMSTEC), and A.Iwasaki (Univ of Tokyo)
Age of basalts if any: O. Ishizuka (AIST)
Petrology of volcanic rocks, metamorphic rocks and meta-basalts: H.Ueta (Hirosaki
Univ)
Geophysics: T.Fujiwara (JAMSTEC)
Biology: H. Kitazato (JAMSTEC)
4-2. Dive#970
Aug. 22 ‘06
Abundance, biodiversity and feeding ecology of deep-sea benthic foraminifera at
abyssal depth: reference site for limestone fauna
Hiroshi Kitazato (JAMSTEC/IFREE4)
4-2-1. Objectives of the dive
On abyssal plain, abundant foraminiferal fauna are recorded from the east
central Pacific Ocean (Gooday et al., 2003; Nozawa et al., in press).
Fauna are mainly
composed of both soft-shelled and agglutinated groups, and scarce in calcareous benthic
foraminifea.
Because, abyssal depth situates below the CCD (Calcite Compensation
Depth) where any of calcite does not remain in the sediment.
However, we found very
rich calcareous benthic foraminiferal fauna from the Palau Trench landward slope at
water depth of 6500 m where a large limestone blocks were exposed (Fujioka et al.,
1994; Fujioka et al., 1996; Kitazato and Fujioka, 1996).
Even though the depth
situates in 2000m deep below the CCD, it is amazing that tests of calcareous
foraminifera are preserved quite well.
are preserved in detail.
below the CCD?
Even the thin spines of planktonic foraminifera
What kind of mechanism do work to remain calcareous fauna
What kind of calcareous benthic species do dwell in the site?
From
where do calcareous benthic species originate?
4-2-2. Dive site
Palau Trench seaside slope at 6º 20.055’, 134º 04.00’E. Landing at 6500 m
and move to 150° direction as shallow as possible to observe, measure and sample
various kind of rocks, sediments and water existed.
4-2-3. Strategy of dive #970
To perform the objectives of the dive, the following dive strategy is proposed
at various stops:
(1) First, submersible land on sediment bottom about 6500m water depth.
(2) If we find the suitable site, take water sample just above sediment surface, 0.5m, 1m,
5m and 10m above the SWI by use of both Gamo-type Pump sampler and
Niskin-type water sampler. First of all, we try to collect 3 pump + 1 Niskin water
samples just above SWI.
Three pump samples from 50cm high, two pump samples
+ one Niskin bottle samples from 1m high, one Niskin bottle sample from 5 m high
and one Niskin from 10 m high.
(3) Then we move to location where sediment surface are well preserved in natural
condition. We shall take nine MBARI cores from the locality.
feeding device.
Set one in situ
Stick in situ fixation device and recover. We deploy a marker on
this site for recovering feeding device during dive #972 by K. Oguri. After taking all
the cores we try to take surface sediments by “Chiritori” sampler.
(4) We climb up to shallower depth as far as the dive is being time-out..
4-2-4. Pay loads:
(1) Niskin-type water sampler x 6, (2) Gamo-type pump sampler x 8 bottles with
temperature probe, (3) 9 MBARI type corers (4) one in-situ feeding device and one in
situ fixation device, (5) 3 6K-type Push corers, (5) Scoop (Chiritori sampler) for taking
sediment.
4-2-5. Co-workers of onboard and shore based studies related with this dive:
Topography: K. Fujioka, and S. Okada
Geology: K. Fujioka (JAMSTEC), H.Wada (Shizuoka Univ), K. Oguri and H.Nomaki
(JAMSTEC)
Water sample: K. Fujioka (JAMSTEC), H. Wada (Shizuoka Univ), K.Oguri, H.Nomaki,
(JAMSTEC), and A.Iwasaki (Univ of Tokyo)
Pore water geochemistry: H. Wada (Shizuoka Univ), K.Oguri and H.Nomaki,
(JAMSTEC), and A.Iwasaki (Univ of Tokyo)
Biology: H. Nomaki, M. Tsuchiya, T. Toyofuku and A. Iwasaki (JAMSTEC)
4-3. Dive#971
Aug. 23 ‘06
A complete cross sectional overview of a huge sunken paleo coral reef at the Palau
Trench forearc 2
Hideki Wada (Shizuoka University)
4-3-1. Objectives of the dive
In the Palau Trench landward slope at water depth of 6500 m, a large
limestone block was found by Shinkai 6500 dive #190 by Fujioka, 1993 and several
dives (#292, 293, 343, 344, 345) were followed successfully (Fujioka et al., 1993,
Fujioka et al., 1995;1996). Results were two major things; A huge limestone block may
be transported from the land, Palau Island Arc and the landward lower slope consists of
serpentinites like Mariana forearc.
Origin and mechanism of the transportation of huge limestone are still unknown
and characterization of serpentinites was not succeeded. Therefore in this cruise we plan
to elucidate the former problem with special emphasis to bio-geochemical aspect.
The main objectives of this dive are;
(1) To elucidate the effect of the flux of dissolved carbonate of the Palau submarine
limestone at the depth of 6500m to the ambient seawater around the limestone,
Following the dive #, to recovery of the culture experiments left keeping the in situ
on the limestone sediments.
(2) Using Gamou type water sampling apparatus, to take water samples just on the crack
condensate water or surface of the limestone block, 0, 0.5m, 1m, above the limestone
and seawater contact with temperature measurement,
Niskin water sampler also
use to collect normal the Pacific deep sea water for carbon14C dating and 13C
isotopic measurements.
(3) To collect sample limestones, and other rocks such as ultramafic and sedimentary
rocks from various depths for reconstruction and make clear the history of forearc
formation in relation to the lower crust and upper mantle structure,
(4) To sample sediments by MBARI and push corers at various depths for the
microbiological and chemical analyses.
(5) To deploy the special type of MBARI corer for In-situ cultivation of benthic
foraminifers.
4-3-2. Dive site
Palau Trench forearc slope at the same position of two days before of this dive
#969, 6º 22.’, º ’E. Landing at 6430 m and move to 60° direction as deep as 6460m
depth, measure and water samples sediment samples and various kind of rocks,
sediments and water existed.
4-3-3. Strategy of dive #971
To best meet the objectives of the dive, the following dive strategy is
proposed at various stops:
(0) Before our landing, about 70~100m above the landing point, first water sample
using the Niskin water sampler will be collected.
After landing,
(1) First, to recover the testing in-situ cultivation system corer keeping left two days
since #969 dive.
(2) Alcohol fixing sample recover at the testing core keeping locality.
(3) Surface floculent layer sediment collection.
(4) Subside to 6460m, to rediscovery of the Black Band in the limestone blocks which
lies about 6425(in previous depth scale with 20m uncertainty.
(5) If we find the suitable fracture site on the top of the limestone, trying to take water
sample just on the limestone body, 0m, 0.5m, 1m, above the body by means of
Gamou type pump sample system and Niskin-type sampler.
(6) Then we move to thinly covered sediment surface of the limestone body to take push
core sample in order to check the sediment thickness then take 9 MBARI core
samples and recover the special MBARI core for the in situ cultivation and fixation
of foraminifers the cultivation system 2 days later. After taking all the cores we try to
take surface sediments by “Chiritori” sampler.
4-3-4. Pay loads:
(1) Niskin-type water sampler x 4, (2) Gamo-type pump sampler x 8 bottles with
temperature probe, (3) 9 MBARI type corers in addition to one special equipment for
special corer with two syringe for in-situ fixation, (4) 3 Push corers, (5) Scoop (Chiritori
sampler) for taking pebbles, (6) 8 mm Video camera (inside pressure hull).
4-3-5. Co-workers of onboard and shore based studies related with this dive:
Topograph: H.Kitazato, and S. Okada
Geology: H.Kitazato (JAMSTEC), H.Wada (Shizuoka Univ), K. Oguri and H.Nomaki
(JAMSTEC)
Water sample: H.Kitazato (JAMSTEC), H.Wada (Shizuoka Univ), K.Oguri and
H.Nomaki, (JAMSTEC), and A.Iwasaki (Univ of Tokyo)
Sediments: H.Kitazato (JAMSTEC), H.Wada (Shizuoka Univ), K.Oguri and H.Nomaki,
(JAMSTEC), and A.Iwasaki (Univ of Tokyo)
Age of basalts if any: O. Ishizuka (AIST)
Biology: H. Kitazato (JAMSTEC)
4-4. Dive#972
Aug. 24 ‘06
Abundance, biodiversity and feeding ecology of deep-sea benthic foraminifera at
abyssal depth: reference site for limestone fauna 2
Kazumasa Oguri (JAMSTEC/IFREE4)
4-4-1. Objectives of the dive
Calcareous benthic foramineferal fauna were found at 6500m depth from
Palau trench (Fujioka et al., 1994; Fujioka et al., 1996; Kitazato and Fujioka, 1996),
even though the depth situates in 2000m deep below calcite compensation depth (CCD)
in typical Pacific Ocean. One hypothetical reason to maintain such fauna would be
caused in diffusion of high concentration calcium ions from a carbonate rock below
sediments (Kitazato and Fujioka, 1996). To measure the calcarious faunal activity,
in-situ incubation device were deployed between dive #969 and #971. On the other
hand, eastern part (seaside slope) of the Palau trench bottom covers with carbonate-free
sediments due to undersaturation of calcium ions. The objective of this dive is to
recover in-situ cultivation system set at dive #970 for measuring non-calcarious faunal
activity.
The main objectives of this dive are;
(1) Recovery of the in-situ incubation device deploying from the dive #970.
(2) Collecting nine cores using with MBARI type push core samplers. The sampling
will be carried out to the identical place for the incubation experiment.
4-4-2. Dive site
Palau Trench seaside slope at 6º 20.055’, 134º 04.00’E. Landing at 6500 m
and move to 150° direction as shallow as possible to observe, measure and sample
various kind of rocks and sediments.
4-4-3. Strategy of dive #972
To perform the objectives of the dive, the following dive strategy are
proposed at various stops:
(5) Go to the location where in-situ cultivation system corer is deploying.
(6) First, recover the testing in-situ cultivation system corer keeping left two days since
#971 dive.
(7) Move slightly in order to collect undisturbed sediment samples.
(8) If necessary, surface sediments are collected using with a “Chiritori” sampler.
(9) Climb up to shallower depth as far as the dive is being time-out.
4-4-4. Pay loads:
(1) Nine MBARI type corers in addition to one special equipment for special corer with
two syringe for in-situ fixation, (2) Three Push corers, (3) Scoop (“Chiritori” sampler)
for taking pebbles, (4) 8 mm Video camera (inside pressure hull).
4-4-5. Co-workers of onboard and shore based studies related with this dive:
Topography: K. Fujioka, and S. Okada
Geology: H. Kitazato (JAMSTEC), H. Wada (Shizuoka Univ), K. Fujioka, H. Nomaki
(JAMSTEC) and A. Iwasaki (Univ of Tokyo)
Sediments: H. Kitazato (JAMSTEC), H. Wada (Shizuoka Univ), K. Fujioka and H.
Nomaki, (JAMSTEC), and A. Iwasaki (Univ of Tokyo)
Biology: H. Kitazato and H. Nomaki (JAMSTEC)
Age of rocks if any:
4-5. Dive Logs
Site： Palau Trench
Scientist： Kantaro Fujioka(JAMSTEC)
Dive Log of
6K Dive #969
Time
(JST)
Dep.
(m)
Alt.
(m)
Head
(Deg)
11:38
6420
60
6457
9
81
Cliff- White carbonate trench wall covered with
grayish sediment
6461
1
46
Sea cucumber trail
11:48
11:51
Landed X=10,Y=240, carbonage bottom, current dir
100N, velocity 5, visibility 8m
6461
11:52
11:57
6458
3
12:05
6434
6
12:13
6428
50m up, run along with the trench wall
327
Changed direction
328
Start Water sampling using with Niskin bottles
10m?
12:18
Description
Toriggered Niskin(Green) , didn't close ahead valve
12:20
6432
5
329
Closed Niskin (Yellow: 5m above sediment surface)
12:28
6433
0
36
Closed Niskin (Blue: sediment surface)
Failed Niskin bottoel sampling (Green, ¥Red: did not
close)
12:29
Start water sampling using "Gamo shiki" pump
sampler
Pump seems working
12:30
12:44
6438
2
35
Pump seems working
12:47
6438
2
35
Pump seems working
12:55
6438
2
35
6355
7
3
13:10
6355
7
146
Pump sampling completed
Wall covered with grayish sediment (carbonacious
sediment?)
Back to previous point, there is no carbonate rocks
13:17
6403
6
355
climbe up the carbonate wall again
13:28
6341
11(?unreliable)
43
6341
10(?)
57
13:37
6339
11
330
Sea cucumber? Purple
landed on the sediment. Check the sediment thickness
using a push core
Dropped the push core, try again. (X=120, Y=380)
Only thin sediments exist here, so try to find a suitable
station
clime up the carbonate wall
13:42
6349
2
335
6350
0
355
6349
0
43
13:06
13:30
13:35
13:36
13:44
13:52
Red shrimp, pellet of sea cucamber, polychaetes
landed on the sediment. Check the sediment thickness
using a push core
MBARI corer Black finished (X=260, Y=320)
13:55
IFREE-MBARI corer Red-Yellow failed (tube off)
14:03
MBARI corer White finished (15-20cm?)
14:05
MBARI corer Red finished (10cm?)
14:07
IFREE-MBARI corer Blue-Yellow finisfed (15cm)
2006/08/21
Remarks
14:10
IFREE-MBARI corer Yellow finished (15cm, top
5cm=normal sed, below 5cm, carbonate? Same for the
other cores)
IFREE-MBARI corer Red-White finisfed (15cm)
14:11
IFREE-MBARI corer Red finished (15cm)
14:15
IFREE-MBARI corer Blue-White finished
14:20
Settled the I-K type in situ feeding core
14:27
Took off the triggers from the in situ feeding core
14:32
In situ EtOH fixation core failed (tube off)
14:40
14:53
Settled SHINKAI Marker (#47), Homer transponder
14:09
6335
10
332
Take off from the bottom
Site: Palau Trench seaside
Scientist: Hiroshi Kitazato(JAMSTEC)
Dive Log of
6K Dive #970
Time
(JST)
Dep.
(m)
Alt.
(m)
Head
(Deg)
6469
2
190
6469
2
6469
1
200
Completion of Niskin sampling: 1 bottle (1 mab, Blue)
11:44
6470
1
189
Niskin sampling failed: 1 bottle (0 mab, Green)
11:48
6470
3
113
Basement rock: Basalt?
11:51
6470
2
58
Landed: Temp 1.7C, Current dir 240C, velosity 3.
11:52
6470
2
52
Start water sampling by using
6470
2
52
Finish water sampling at 0 mab and start water sampling at 0.5 mab
6470
2
52
Finish water sampling at 0.5 mab and start water sampling at 1mab
Description
2006/08/22
Remarks
Completion of Niskin sampling: 2 bottles (10 mab, 5 mab)
11:38
11:39
Seabottom: muddy sediment
11:40
Sandstone
"Gamo shiki" sampler
12:08
12:19
12:26
6470
3
30
Water sampling with "Gamo Shiki" completed.
12:32
6470
3
31
Try rock sampling
12:36
6470
2
34
1 pc of basalt rock from outcrop
12:39
6469
1
71
Run toward degree 100
12:48
6458
1
101
12:50
6459
1
41
6459
1
6
13:04
6442
2
100
Landed: test for push core sampling
This place is not suitable for core sampling due to thin
sediment.
Big breccia (X=20, Y=-670)
13:06
6428
2
100
Bottom is covered by basalt rocks
13:07
6424
2
99
Any big rocks exist here
13:11
6405
2
100
Big basalt rocks
13:15
6389
2
100
White hard substrate
13:24
6366
3
26
6366
3
34
13:32
Landed on the mud sediments. Check the sediment thickness.
(X=-40, Y=-290), sea cucamber and poluchaete were
observed.
IFREE-MBARI Blue finished (15cm, top 5-10cm=mud, below
5cm=white)
IFREE-MBARI Blue-Yellow finished (15cm)
13:36
IFREE-MBARI Yellow (cooler corer) finished (15cm)
13:39
IFREE-MBARI Red finished (20cm)
13:43
IFREE-MBARI Red-Yellow finished (15cm)
13:45
MBARI Red finished (10-15cm)
13:49
MBARI White finished (10-15cm)
12:55
13:29
6365
3
34
Sandstone
Sandstone
(X=-70, Y=-460)
Move forward few meters (?)
13:52
Sandstone
MBARI Black finished (15cm, not so white)
14:03
IFREE-MBARI Red-White finished (5cm brown and 15cm
white)
Settled in situ feeding core
14:05
Took off the triggers from the in situ feeding core
14:09
In situ EtOH fixation failed (Head Off, again)
14:21
Settled Marker (#48) and Homer (#78)
13:58
14:29
14:36
14:39
6364
2
31
Basalt sampling (X=-40, Y=-270)
Finish the basalt sampling
6361
2
46
Take off from the bottom
Site: Palau Trench
Scientist: Hideki Wada(Shizuoka University)
Dive Log of
6K Dive #971
Time
(JST)
Dep.
(m)
Alt.
(m)
Head
(Deg)
11:51
6350
3
29
Ripple mark
6352
2
339
Landed: botom mud, 6m sight, Current dir/strength none,
ctd 7.2C, 0.4C
11:54
before
11:54
100
Description
Niskin Blue completed
11:58
6342
6
322
Move to homer (in situ feeding core station)
12:08
6349
3
312
Found the homer and marker (X=340, Y=260)
12:16
6350
2
237
Recovered the in situ feeding core
12:20
6350
2
257
Recovered the homer and marker
6350
2
268
IFREE-MBARI Red finished (20cm, but the surface may be
contaminated by calcareous ooze disturbed at the previous dive)
12:26
12:35
IFREE-MBARI Red -Yellow finished (20cm)
12:37
IFREE-MBARI Green finished
12:39
IFREE-MBARI Blue finished
12:40
Feeding corer finished
12:43
MBARI White finished (may not the surface sediment)
12:51
6349
1
212
Move to another position due to the visiblity
13:01
6345
1
329
13:16
6326
1
X=360, Y=210
Corering had been completed (7 cores in the previous
position)
Move to position X=350, Y=520
13:24
6354
1
99
Coil-like trail (feeding trail or fecal trace by worm?)
13:27
6363
2
101
X=380, Y=370
13:36
6392
4
92
Go down to water depth of 6460m
13:45
6441
2
92
X=350, Y=610
13:49
6469
1
77
6467
7
325
6450
3
330
6415
1
293
X=350, Y=660
Changed heading, X=350, Y=710, climbe up the
limestone wall
X=410, Y=680, Niskin Red completed
X=460, Y=610, start the water sampling with Gamo-type
sampler
Now taking the sixth water sample (6th out of eight)
6415
2
256
13:08
13:58
14:01
14:20
14:41
14:52
Gamo-type water sampling cmpleted
Niskin yellow finished, but the Niskin green failed again…
14:54
Take off from the bottom
2006/08/23
Remarks
Site: Palau Trench
Scientist: Kazumasa Oguri(JAMSTEC)
Dive Log of
6K Dive #972
Time
(JST)
Dep.
(m)
Alt.
(m)
Head
(Deg)
11:40
6345
7
2
6350
4
356
Niskin Red finished
Landed on the bottom. Visiblity = 6m, temperature unknown,
sediment = rock, weak current (X=-100, Y=-180)
Niskin Blue had been finished before landing
11:43
3
Description
Remarks
11:48
6349
5
290
Move to the homer
12:00
6365
3
47
Settled in front of the in situ feeding core
12:05
6365
3
54
Recover the in situ feeding core and the homer
12:26
6360
3
124
X=-100,Y=-230, strat the sediment corering
12:30
6360
3
50
IFREE-MBARI Green finished (could not see the core length)
12:36
6358
2
100
Find a new suitable station with course 100
12:40
6350
1
85
Sandstone (X=-130,Y= -150)
12:41
6349
3
59
Landing. Start the sediment corering. (X=-130, Y=-140)
12:42
IFREE-MBARI Red-Yellow prepared
12:45
a white, long animal (15cm?) was observed
12:46
IFREE-MBARI Red-Yellow finished
12:48
IFREE-MBARI Blue-Yellow finished
12:53
MBARI White finished
MBARI Red finished
12:56
13:00
6349
3
54
Find a new suitable station with course 100
13:02
6349
1
54
Landing. Start the sediment corering. (X=-130, Y=-130)
13:06
In situ EtOH fixation (IM Blue) finished
13:08
IFREE-MBARI Red finished
13:10
MBARI Black finished
13:15
6345
3
49
IFREE-MBARI White-Red finished
13:20
6340
4
50
Move to shallower station (course 70)
13:26
6330
46
Landing. Take a rock sample (mudstone???) (X=-90, Y=-50)
13:36
6327
1
79
Landing. Fail to take a rock sample.
13:46
6327
3
96
Xenophyophora sampling (X=-70, Y=-50)
(X=-80, Y=-50)
Surface sediment sampling finished
14:00
2006/08/24
14:12
6300
2
111
Course 100 (X=-80, Y=130)
14:29
6256
4
101
Many sandstones. (X=-180, Y=480)
14:35
6222
2
102
Large sandstones (X=-230, Y=660)
14:40
6200
2
102
Take off from the bottom (X=-260, Y=780)
5. Methods, Results, and future studies for individual study
5-1. Water sampling and analysis on board
5-1-1. Multi-sampling system
For the purpose of collecting water samples at accurate depths above sea bottom,
a multi-sampling system driven by a deep-sea pump developed by H. Sakai and T.
Gamo (Ocean Research Institute, the University of Tokyo) was used (Sakai et al., 1990;
Ishibashi et al., 1994; Gamo et al., 1994; Tsunogai et al., 1994) at dive #969~#971.
Figure 4.2.1 shows schematic diagram of the water sampler, which consists of (i) a deep
sea impeller pump (Pelagic Electronics, Model 5013A-P), (ii) a 12 port automatic
revolving switch valve (Nichiyu-Giken Kogyo, Co. Ltd.), and (iii) eight water sampling
cylinders.
The system is installed just below the pressure hull of Shinkai 6500. Although the
valve can select up to 12 different cylinders, we used 8 cylinders because of the limited
space below the pressure hull. The cylinders are made of plexyglas, and hold volume of
about 750 ml. Prior to a dive, the cylinders are filled with distilled water (DW) in order
not to contain air bubbles. As shown in Fig.5.1.1, there is a cylindrical piston inside
each cylinder, which moves from one end to the other end when the DW is sucked out
by the deep sea impeller pump so that seawater is introduced to the cylinder through the
sample inlet line.
The sampling time is usually between 90 to 110 sec per cylinder. The revolving
valve sequentially selects a sampling cylinder to be pumped out. It takes about 30 sec to
complete changing the next valve. The impeller pump and the revolver valve are
controlled from the submersible. Since the system is set up just below the pressure hull,
the observer cannot watch the operation through the view ports of the submersible.
Instead, the observer can confirm the normal operation of the system by observing a
spinning of a hydraulic turbine attached with the pump outlet and shimmering of DW
with the video camera of Shinkai 6500.
The sample inlet tube is coupled with a Pt resistance thermometer (0 to 400C) to
measure temperature of seawater passing through the inlet tube. The temperature is
displayed inside Shinkai 6500 in real time. The inlet tube as well as the thermometer is
hold in front of the right sample basket of Shinkai 6500. For seawater sampling, a
manipulator of Shinkai 6500 grasps the inlet tube in order to set correct height from the
sea bottom. The tube is connected with the sample cylinders through a flexible Teflon
tube (i.d.= 8mm) of ca. 3m long, which is filled with seawater (ca. 150 ml) before dive.
To avoid contamination of the seawater in the inlet tube, the first and fourth cylinders
are used for flushing of the seawater in the Teflon tube.
Figure 5.1.1. Schematic diagram of the ORI pump sampling system.
5-1-2. Niskin bottles
In addition to the multi-sampling system, 2 litters of Niskin bottle samplers were
installed to the both sample baskets. These bottles were closed with manipulator
operation at respective depths.
5-1-3. Sampling manner after the collections
After the dives, sample cylinders were removed and brought to laboratory in
Yokosuka. Seawater samples were collected for the purpose to measure pH, total
alkalinity (T.A.), dissolved oxygen (DO), ΣCO2 and δ13CDIC and Ca2+, respectively. pH,
T.A. and DO were measured on board. For pH and T.A. measurements, PHM220 pH
meter, PHC2001 pH electrode, REF251 reference electrode, and T201 temperature
probe (Radiometer Analytical) were used. T.A. was measured by adding 15 ml of
0.009N hydrochloric acid into 50 ml of sample seawater (Nishimura and Tsunogai,
1981). Samples for DO measurement were once stored in DO bottles, and they were
measured with Winlker titration. Samples for ΣCO2 and δ13CDIC measurements were
sealed in 100 ml bial bottles in order not to contain gas phase, adding to 100 µl of
saturated HgCl3 solution, respectively. Samples for Ca2+ measurement were sealed in 50
ml bial bottles. The amount of respective ∆14C samples were 150 ml. They were stored
in 250 ml of Schott-Duran bottles prior to be filled with Argon gas to prevent
contamination of 14CO2 from the air.
5-1-4. Sampling results
At dive #969, all the sampling with multi-sampling system was succeeded.
However, two Niskin bottle sampling at 2 m and 10 m above sea bottom were failed due
to insufficient close of the bottle caps. At dive #970, almost bottles of multi-sampling
system were contaminated by fine grained sediments, except for the last (No.8, at 1 m)
bottle. The internal pistons of No. 3 (at 0 m) and No. 6 (at 0.5 m) bottles were stacked
and they could not collect the samples. Two Niskin bottles (1 m and 3 m above sea
bottom) were not closed at the site. At dive #971, the internal piston of No. 7 (at 1 m)
bottle was not moved. Two Niskin bottles (0 m and 1 m above sea bottom) were not
closed. At dive #972, multi-sampling system was removed and two Niskin bottles were
loaded in the basket. Water samples were recovered from 3 m and 10 m, respectively.
5-1-5. Preliminary results of pH, T.A. and DO
Figures 5.1.2a, b, and c shows pH, T.A. and DO profiles above sea bottom,
respectively. In these figures, the data from island side (carbonaceous sea bottom; dives
#969 and #971) are indicated as square dots, and those from trench side (non
carbonaceous sea bottom; dives #970 and #972) are represented as triangle dots,
respectively. pH of the sea water ranged from 7.71 to 7.81, and higher values were
observed in bottom water. T.A. ranged from 2.35 to 2.51 meq l-1. Unlike pH, these
profiles showed relatively constant except from 0.5 m above sea bottom (ASB). As to
see Figs. 6.2a and b, there do not have any trends between two different sites. DO
values ranged from 150 to 345 µM, and the water close to the sea bottom were higher
values. However, 345 µM from 0 m ASB is close to saturation level, so it seems too
high to consider normal O2 concentration at deep water. Thus, the value from 0 m to 1
m may reflect contamination of O2 in air during the preservation to the sample bottles,
or affect to distilled water in the cylinder. If latter effect is true, distilled water must take
effect to pH, T.A., and other values that will be measured after the cruise. To confirm
the contamination of the distilled water to the samples, it would be necessary to measure
salinity for all the samples using rest water for ΣCO2, δ13CDIC or Ca2+ measurements.
Figure 5.1.2, (a) pH, (b) T.A., and (c) DO profiles above sea bottom.
5-2. In situ feeding experiment
Incorporation of 13C-labeled glucose by trench benthic communities
Hidetaka Nomaki and Hiroshi Kitazato
5-2-1.Introduction
Phytodetritus, originated from primary production, transports substantial amount
of carbon from ocean surface to the seafloor. The phytodetritus and its degraded
components are thought to be major food sources for benthic ecosystems. At the same
time, dissolved organic carbon (DOC) degraded by benthic communities is also an
important food source for the benthic ecosystems in a way of direct incorporation or via
bacteria. In particular, DOC should be more important carbon sources in case of hadal
zone, where the phytodetritus is poorly derived. In this study, we operated a stable
carbon isotope labeled experiment in situ to know the hadal zone carbon pathways
originated from DOC on the seafloor. Incorporation of labeled glucose into benthic
organisms will be analyzed each organic compound level.
5-2-2.Materials and Methods
The in situ tracer experiment was carried out at the Palau trench in YK06-11 R/V
Yokosuka cruise. Total 2 culture cores were prepared for the experiment (Figure 5.2.1,
Table 5.2.1). The surface sediment area of the core is 52.8 cm2 (φ=8.2cm). Every core
has couple of 5ml syringes that can contain
13
C-labeled glucose (Cambridge Isotope Co.
ltd).
One culture core (C-2; Carbonate site 2 days incubation) was settled on the
seafloor (water depth 6350 m) by the manned submersible Shinkai 6500 at dive #969
(21st August, 2006, Figure 5.2.2a). This site is located in landward side of the Palau
trench, where the huge carbonate outcrops exist (Fujioka and Kitazato 1994, Kitazato
and Fujioka 1996). The other culture core (S-2; Seaward site 2 days incubation) was
settled on the seafloor (water depth 6365 m) by the Shinkai 6500 at dive #970 (22nd
August, 2006, Figure 2b). This site is located in seaward side of the Palau trench. After
positioning the culture cores,
13
C-labeled glucose were introduced to the surface
sediments by taking off the triggers of the head part of the core. On the dive # 971 (23rd
August, 2006), C-2 core was recovered, and another culture core (S-2) was recovered at
dive #972 (24th August, 2006). Reference cores (C-B and S-B; Carbonate site
Background, and Seaward site Background) were also taken at each site to investigate
natural isotopic compositions of both dissolved inorganic carbon of seawater and
organic matters in the sediments.
5-2-3.Preliminary results: On board processing
On board, recovered culture cores and two reference cores were kept at 4°C prior
to core processing (within three hours). Overlying water was collected for the
determination of
13
C concentration in dissolved inorganic carbon (DIC) caused by
respiration of benthic communities. Three replicate water samples (20ml each) were
sampled from the overlying water of the core. They were fixed by adding a drop of
AgCl2 solution and preserved at low temperature. Sediments were sliced at 1-cm
intervals from 0 to 5 cm in depth followed by 5-7, and 7-10cm sediment depth samples
(Table 5.2.1). Xenophyophores, a giant protozoan living in the surface sediments, were
picked out from the sliced sediments using forceps. The rest of the sediments were used
for an analysis of bulk organic matter. Both samples were kept frozen at –80°C until the
analysis. These samples will be analyzed for the determination of carbon isotopic
compositions of lipid compounds in benthic organisms.
Table 5.2.1. Sample list of in situ experimental sediment cores.
Core name
C-2
S-2
C-B
S-B
Recovered Dive #
971
972
971
970
Set Dive #
969
970
-
-
Overlying water
3 samples
3 samples
3 samples
3 samples
0-1cm
BS+Xeno
BS+Xeno
BS+Xeno
BS+Xeno
1-2cm
BS
BS
BS
BS+Xeno
2-3cm
BS
BS
BS
BS+Xeno
3-4cm
BS
BS
BS
BS
4-5cm
BS
BS
BS
BS
5-7cm
BS
BS
BS
BS
7-10cm
BS
BS
BS
BS
BS = bulk sediment sample
Xeno = Xenophyophore
Trigger case
Syringe
Core
Figure 5.2.1. I-K type in situ feeding core equipped with the 13C-labeled glucose. Inner diameter of the core
is 8.2 cm. Trigger case, syringes containing the 13C-labeled glucose, and the core.
a (Dive #969)
b (Dive #970)
Marker
Homer
Marker
Homer
Figure 5.2.2. In situ feeding cores on the deep-sea floor. a) Carbonate site at the Dive #969 (6350m), b) Seaward site at
the Dive #970 (6365m). Homer and Marker were also settled on the seafloor adjacent to in situ feeding core.
6. Proposal for the future studies
Storyboard tells us a collapse and huge sliding of a large coral reef to the trench bottom
at the southern tip of the Palau Trench in the Philippine Sea.
Using geophysical data such as bathymetry, gravity and magnetic data and geologic
observation by Shinkai 6500 we will plan to discuss about the possibility of a huge coral
reef collapsed down to the trench bottom to have a huge slope failure resultant
formation of a large tsunami. (K. Fujioka, H. Kitazato and H. Wada)
* Sediment core samples
1) Faunal studies of benthic foraminifera will be held both E and W sites for
comparison between calcareous and non-calcareous bottom environments. (Iwasaki,
Gooday)
2) Genetic analyses will be held for soft-shelled foraminifera (Iwasaki, Tsuchiya)
3) TEM observation for soft-shelled foraminifera (Iwasaki, Uematsu)
4) Historical biology of calcareous foraminiferal fauna on limestone block will be
submitted to quite high-quality journal (Kitazato together with Fujioka, Wada, Iwasaki,
Nomaki, Oguri and Gooday)
* ln situ feeding experiment
Assimilation rate of dissolved organic carbon by deep-sea benthic foraminifera
will be measured. Mineralization rate of organic carbon by total benthic community will
be evaluated from
13
C concentrations in DIC of the overlying water. Lipids will be
extracted from both bulk sediment and Xenophyophores. Identification and
quantification of separated lipids will be performed by GC/MS. Compounds specific
carbon isotopic compositions will be determined by using GC/C/MS. Using these data,
incorporation and alteration of glucose (DOC) by trench communities will be examined.
These data will be compared for those of bathyal Sagami Bay, where the phytodetritus
plays major role of the benthic carbon flow. (Nomaki)
* Water sample
Outflow flux of calcium ion will be measured for estimating dissolution rate and
saturation of calcium on limestone block at 6500m. In order to understand why and how
to maintain calcareous benthic fauna at 6500 m depth, understanding carbonate system
at sea water is important. First of all, Ca2+ concentration at each depth above sea bottom
will be measured. Then, Ca2+ profiles from each site are compared and calculated to
obtain Ca2+ flux from the sediments. As the same, both ΣCO2 and δ13CDIC will be
measured. Using these values, pH and T.A., solubility of Ca2+ will be calculated.
δ13CDIC are also used to compare with those from calcareous foraminiferal tests obtained
from the sediment cores. (Oguri, Wada)
* Geology
Geological explanation will be given why reef limestone blocks are distributed in
6500m deep at the Palau Trench using geologic age and paleoenvironmental data from
limestone and geomorphological analysis of seabeam maps (Fujioka, Wada)
Appendix 2. Videotape list
Camera-1
Camera-2
miniDV (60min)
S-VHS (120min)
miniDV (60min)
S-VHS (120min)
#969 (20060821)
3
2
3
2
#970 (20060822)
3
2
3
2
#971 (20060823)
3
2
3
2
#972 (20060824)
3
2
3
2
Dive No.
Appendix 3. Photographs of pay load at each dive.
Dive #969, whole view of the pay load.
Dive #969, right basket.
Dive #969, left basket.
Dive #969, multiple water sampler.
Dive #970, whole view of the pay load.
Dive #970, right basket.
Dive #970, multiple water sampler.
Dive #970, left basket.
Dive #971, whole view of the pay load.
Dive #971, right basket.
Dive #971, multiple water sampler.
Dive #971, left basket.
Dive #972, whole view of the pay load.
Dive #972, right basket.
Dive #972, left basket.
Appendix 4. Topography and Track charts