Hiroshi Kitazato (IFREE, JAMSTEC)

Transcription

1 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)

2 Motivation-1 (Monitoring of material cycles at continental margins)

3 Carbon burial at continental margins Seibold and Berger, 1996

4 Sagami Bay ー long-term monitoring ー For the purpose to know how both material transportation and carbon burial occur in bathyal basin at active continental margin, long-term monitoring of carbon budget both water column and basin floor have long been carrying out at Sagami Bay since 1991.

5 color fluorescent flux by water of benthic nepheloid layer at long-term deep-sea observatory off Hatsushima of surface sediments with multiple situ monitoring and experiments with submersible / ROV / profiling lander systems Kitazato, H. ed., 2003, Prog. Oceanogr.

6 Transportation pathways of organic carbon ー exemplified from Sagami Bay ー Tokyo Bay Sagami Bay Downslope input (terrestrial, coastal) Organic/inorganic matter artificial compounds Vertical input (pelagic) Marine organic matter clay Kitazato H. ed., 2003 ProOce mgc/m 2 /day Advection?

7 Carbon Budget at Sagami Bay Sinking organic carbon has consumed at benthic food webs. However, many of them are accumulated in the sediment. megabenthos + Carbon burials into sediment advection are forced both with terrestrial input of organic / inorganic materials and shallow RPD level at SWI Kitazato, 2003; Nomaki et al., submitted deposition Meiobenthos Respiration production Burial in sediment 100mgC/m 2 /day central Sagami Bay: 0.1Gt / ye

8 Material cycles and strata formation at active ocean margins When we discuss material cycles and strata formation at oceans, bio-geo geo-chemical activities at SWI give important boundary conditions for these processes.

9 Monitoring of material cycles at sediment-water interface 炭素サイクル Wada,2002

10 Motivation-2 (anoxic environment)

11 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 euxinic environments, whereas the later is well ventilated oxic environment. 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.

12 Changes in redox boundary since 4.6 Ba Origin of Life Falkowski et al., 2004 H + H + O 2 H + O 2 O 2 Kitazato 2005 Oceanic Anoxic Event(OAE)

13 Changes in Earth s s interior, climate and biotic evolution Since 150 Ma

14 Oceanic Target Anoxic Event-2 Livello Bonarelli at C/T boundary (94 Ma) Turonian limestone Cenomanian limestone 1 m-thick finely laminated black shale Intercalated in pelagic limestone Duration: ky (Arthur and Premoli-Silva, 1982; Ohkouchi et al., 1999)

15 Schematic oceanic environments during the OAE-2, mid-cretaceous Diazotrophic cyanobacteria Green sulfur bacteria Ohkouchi et al., 2006

16 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.

17 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 area cf. Arabian Sea, off Namibia High input of terrestrial organic carbon cf. coastal anoxic environments Permanent ocean stratification due to Megaplume or brine water inputs cf. Red Sea

18 Modern Anoxic Environments cf. Black Sea cf. Red Sea cf. Arabian Sea Coastal Anoxia Modified from Herrle, Tuebinger Mikropal. Mitteil., 2002

19 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.

20 Anoxic ciliates house Endosymbiotic Bacteria in cell Methane producing bacteria +hydrogenosome Fenchel and Finley, 1995

21 Foraminifers live in euxinic environment Both sulfur oxidizing bacteria and sequestered diatom -originated chloroplast are housed in cytoplasm as symbionts Bernhard, 2003

22 Nitrogen cycle

23 Anammox Nitrogen oxidation from NH 4+ to N 2 under anoxic environment Kuypers et al., 2003

24 By courtesy of A. Gooday

25 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.

26 Research Tactics

27 In situ approaches In situ experiments In situ measurement, monitoring and observations

28 in situ feeding experiments

29 Outline of in situ 13 C- 15 N feeding experiments 1) Settle culture cores on the seafloor by ROV Hyper-dolphin. 2) Introduce 13 C- 15 N 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. Bulk analyses After decalcify tests, EA:TOC content IRMS:Carbon isotopic composition Lipid analyses After extracting organic compounds, Permanent station 1450m GC/MS:identification, quantification GC/C/MS: Carbon isotopic composition

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31 Changes in seasonal assimilation of organic carbon by benthic foraminifers at SWI Most POC has been consumed for respiration Nomaki et al., 2005

32 In situ Measurements and Monitoring (O 2, ph )

33 Laboratory observation Intertidal sediment with harpacticoid copepods and nematodes QuickTimeý Dz None êlí ÉvÉçÉOÉâÉÄ Ç Ç±ÇÃÉsÉNÉ`ÉÉǾå ÇÈÇžÇ½Ç ÇÕïKóvÇ-ÇÅB

34 2D-O 2 optode system for in situ observation collaborative cruise with IFREE, JAMSTEC / Univ. Copenhagen / MPI-Bremen / Univ. Tübingen (2003) Elinor-type Lander Filter Dichroic mirror Optode film CCD camera Lens LEDs Mirror

35 Time-lapse optode images obtained from NT06-05 cruise give 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

36 Bioirrigation by polychaete Courtesy from Glud and Staahl

37 R/V Yokosuka Shinkai 6500

38 Target Area High productivity anoxic ocean environment 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.

39 Arabian Sea

40

41 Off Goa

42 Cowie, 2005

43 Season: post monsoon period (October - Ship/submersible: Yokosuka / Shinkai Dives: 30 dives at five stations (500, 900, 1500, 2000, 3000m)

44 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

45 Connection to the International Program COMARGE Project, Census of Marine Life (CoML) IMBER?