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Investigation on Bio-Geo-Chemical cycles and sedimentary processes at sediment-water
interface under Oxygen Depleted Environments:
Dive cruise at Indian Margin of the Arabian Sea
Hiroshi Kitazato(IFREE, JAMSTEC)
Motivation-1(Monitoring of material cycles at
continental margins)
Carbon burial at continental margins
Seibold and Berger, 1996
Sagami BaySagami Bayーlong-term monitoringー
1991〜2006
For the purpose to know For the purpose to know how both material transportation how both material transportation
and carbon burial occur inand carbon burial occur inbathyalbathyal basin at basin at
active continental margin,active continental margin,longlong--term monitoring term monitoring
of carbon budget of carbon budget both water column and both water column and
basin floor basin floor have long been have long been
carrying out at Sagami Bay carrying out at Sagami Bay since 1991.since 1991.
Monitoring:@Ocean color satellite@Natural fluorescent light@Chlorophyll-a measurement@sinking flux by sediment-
trap @CTD-CMS water sampler @Observation of benthic
nepheloid layer at long-term deep-sea observatory off Hatsushima Island
@collection of surface sediments with multiple corer
@in situ monitoring and experiments with submersible / ROV / profiling lander systems
Kitazato, H. ed., 2003, Prog. Oceanogr.
Transportation pathways of organic carbonTransportation pathways of organic carbonーーexemplified from Sagami Bayexemplified from Sagami Bayーー
Advection?
Organic/inorganic matterartificial compounds
DownslopeDownslope inputinput(terrestrial, coastal)(terrestrial, coastal)
Vertical inputVertical input(pelagic)(pelagic)
Marine organic matterclay
mgC/m2/day
Tokyo Bay Sagami Bay
Kitazato H. ed., 2003 ProOce
Carbon BudgetCarbon Budgetat Sagami Bayat Sagami Bay
Sinking organic carbon has consumed at
benthic food webs.However, many of them are
accumulated in the sediment.
Carbon burials into sedimentare forced
both with terrestrial inputof organic / inorganic materials
andshallow RPD level at SWI
RespirationRespiration
productioproductionn
depositiondeposition
megabenthosmegabenthos++
advectionadvection
Kitazato, 2003; Nomaki et al., submitted
MeiobenthosMeiobenthos
Burial in sediment Burial in sediment 100mgC/m100mgC/m22/day/daycentral Sagami Baycentral Sagami Bay:: 0.1Gt / ye/ ye
Material cyclesMaterial cyclesand strata formationand strata formation
atatactive ocean marginsactive ocean margins
When we discussWhen we discussmaterial cyclesmaterial cycles and and
strata formation strata formation at oceans,at oceans,
biobio--geogeo--chemical activities chemical activities at SWIat SWI give important give important boundary conditionsboundary conditionsfor these processesfor these processes. .
Monitoring of Monitoring of material cyclesmaterial cycles
at sedimentat sediment--waterwaterinterfaceinterface
炭素サイクル
Wada,2002
Motivation-2(anoxic environment)
Oceanic Anoxia• When we have taken an overview the Earth’s
environmental history since 4.6Ba, we easily recognize two distinct environmental settings. Earlier half of the Earth’s history is characterized by anoxic and/or euxinicenvironments, whereas the later is well ventilated oxicenvironment. During the anoxic Earth’s environments, there may exist both different biogeochemical cycles and depositional processes even in the ocean.
• Both banded iron formation and black shales are typically formed as sediments during the anoxic marine environments. Because, microbial ecosystem which is mainly composed of eubacteria, archaea and protists, may sustain primary production and material cycles in the anoxic ocean.
Changes in redox boundary since 4.6 Ba
Oceanic Anoxic Event(OAE)
HH++
OO22 OO22OO22
Falkowski et al., 2004
Kitazato、2005
HH++
Origin of Life
HH++
Changes in EarthChanges in Earth’’s interior, climate and biotic evolutions interior, climate and biotic evolutionSince 150 MaSince 150 Ma
Target
1 m-thick finely laminated black shaleIntercalated in pelagic limestoneDuration: 350-800 ky
(Arthur and Premoli-Silva, 1982; Ohkouchi et al., 1999)
Cenomanian
limestone
Turonian limestone
Oceanic Anoxic Event-2 Livello Bonarelli at C/T boundary (94 Ma)
Schematic oceanic environments during the OAE-2, mid-Cretaceous
Ohkouchi et al., 2006
Diazotrophic cyanobacteriaGreen sulfur bacteria
Modern Analogue
• Investigation of analogous environment at modern oceans may be the most effective approach to understand for elucidating ancient anoxic marine environmental systems and also for understanding mechanisms of biotic evolution.
• Black Sea, Red Sea, Northern Arabian Sea and California Border Land should be typical cases for oceanic dysoxic/anoxic environments.
Four probable origins for the creation of anoxic environments
• Permanent ocean stratification covered with fresh water on sea surface cf. Black Sea, Japan Sea
• High surface productivity under upwelling areacf. Arabian Sea, off Namibia
• High input of terrestrial organic carboncf. coastal anoxic environments
• Permanent ocean stratification due to Megaplumeor brine water inputs
cf. Red Sea
Modified from Herrle, Tuebinger Mikropal. Mitteil., 2002
Modern Anoxic Environmentscf. Black Sea cf. Red Sea
cf. Arabian Sea Coastal Anoxia
What kind of organisms does dwell in anoxic environments ?
• Eubacteria, Archaea and Protista dwell in anoxic/euxinic environments.
• Bacterial ecto- and endosymbiosis is commonly observed in anoxic protists. In particular, endosymbiosis may be important for thinking about evolution of eukaryotes.
Anoxic ciliates houseEndosymbioticBacteria in cell
Methane producing bacteria+hydrogenosome
Fenchel and Finley, 1995
Bernhard, 2003
ForaminifersForaminiferslive inlive in
euxiniceuxinicenvironmentenvironment
Both sulfur oxidizing bacteria and sequestered
diatom-originated
chloroplast arehoused in
cytoplasm as symbionts
Nitrogen cycle
AnammoxAnammox
Nitrogen oxidation from NH4
+ to N2 under anoxic environment
Kuypers et al., 2003
By courtesy of A. Gooday
Questions and Purpose
• What kinds of sedimentary processes do take place at oxygen minimum zone and the surrounded environments? How do biogeochemical cycles exist at anoxic seas? What kinds of biotic activities do exist under oxygen depleted environments?
• For the purpose to elucidate depositional processes and biogeochemical cycles at sediment-water interface (SWI) under oxygen depleted environment, we plan to carry out multidisciplinary research cruise at Indian sector of the Arabian Sea.
Research Tactics
In situ approaches
In situ experimentsIn situ measurement, monitoring and
observations
in situin situ feeding experimentsfeeding experiments
1) Settle culture cores on the seafloor by ROV Hyper-dolphin.
2) Introduce 13C-15N labeled food (Dunaliella, diatom, bacteria and glucose) on the seafloor into semi-closed culture devices.
3) After injection of foods, recover culture devices after days of incubation.
4) Cut sediment surface and sort living foraminifera from the sediments.
Outline of in situ 13C-15N feeding experiments
Bulk analyses → After decalcify tests,
EA:TOC contentIRMS:Carbon isotopic composition
Lipid analyses → After extracting organic compounds,
GC/MS:identification, quantificationGC/C/MS: Carbon isotopic composition
Permanent station 1450mPermanent station 1450m
Changes in seasonal assimilation of organic carbon Changes in seasonal assimilation of organic carbon by benthic foraminifers at SWIby benthic foraminifers at SWI
Nomaki et al., 2005Most POC has been consumed for respiration
In situIn situ Measurements and Measurements and MonitoringMonitoring(O(O22, pH , pH ))
Laboratory observationIntertidal sediment with harpacticoid copepods
and nematodes
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ǙDZÇÃÉsÉNÉ`ÉÉǾå©ÇÈǞǽDžÇÕïKóvÇ-Ç�ÅB
2D2D--OO22 optode system for optode system for in situin situ observationobservationcollaborative cruise with IFREE, JAMSTEC / Univ. Copenhagen collaborative cruise with IFREE, JAMSTEC / Univ. Copenhagen
/ MPI/ MPI--Bremen Bremen / Univ. / Univ. TTüübingenbingen (2003)(2003)
ElinorElinor--typetypeLanderLander
CCD CCD cameracamera
LEDsLEDs
MirrorMirrorOptodeOptode filmfilm
FilterFilter
DichroicDichroicmirrormirror
LensLens
Time-lapse optode images obtained from NT06-05 cruisegive us more information about sediment dynamics and
behavioral ecology of micro-benthos dwelled in the deep-sea sediment
1 cm
Courtesy from Glud and Staahl
Bioirrigation by polychaete
Courtesy from Glud and Staahl
R/V YokosukaShinkai 6500
Target Area
• High productivity anoxic oceanenvironment at Arabian Sea: Indian continental margin close to Goa is a target field for dive cruise. Because Indian continental margin is known as the most oxygen-depleted OMZ at Arabian Sea.
Arabian Sea
Off Goa
Cowie, 2005
500900
15002000
3000
Cruise
@ Season: post monsoon period (October - November)
@ Ship/submersible: Yokosuka / Shinkai6500
@ Dives: 30 dives at five stations (500, 900, 1500, 2000, 3000m)
Dive plan
• 6 dives at one station• First dive: set profiling lander /
feeding devices / benthic chambers• Second~fifth dives: collecting cores,
benthic organisms and recover feeding devices → on board experiments
• Sixth dive: recover lander system
Connection to the International Program
• COMARGE Project, Census of Marine Life (CoML)
• IMBER ?