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BIOSOPE CRUISE

BIOSOPE CRUISE. Main objectives To study the biogeochemical properties of different trophic regimes in the south east Pacific To describe distribution of biogenic elements and productivity levels with special attention of new production. Patrick RAIMBAULT Nicole GARCIA Gerd SLAWYK.

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BIOSOPE CRUISE

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  1. BIOSOPE CRUISE Main objectives To study the biogeochemical properties of different trophic regimes in the south east Pacific To describe distribution of biogenic elements and productivity levels with special attention of new production Patrick RAIMBAULT Nicole GARCIA Gerd SLAWYK Laboratoire d’Océanographie et de Biogéochimie Campus de Luminy 13288 Marseille cedex 09

  2. BIOSOPE New production and export carbon N2 CO2 CO2 Primary production Dissolved organic matter COD, NOD, POD N2 Nitrate Nitrite Ammonium Phosphate Silicate Diazotrophy Phytoplankton Trophic chain EXCRETION DO15N/DO13C New production Euphotic zone Microbial loop Regenerated production Particulate organic matter:COP, NOP, POP, d15N HYDRODYNAMIQUE REGENERATION (NH4, NO3) sédimentation Nitrate Nitrite Ammonium Phosphate Silicate Dissolved organic matter COD, NOD, POD Detritical material COP, NOP, POP Deep ocean EXPORT PRODUCTION Conceptual scheme of carbon and nitrogen cycles in the euphotic zone indicating the different nutrient pools (in blue) and biological processes (in red) measured during the BIOSOPE cruise.

  3. UPWELLING New production and export carbon CO2 Nanoplankton CO2 Primary production Dissolved organic matter COD, NOD, POD N2 Nitrate Phosphate Silicate Phytoplankton New production Trophic chain EXCRETION DO15N/DO13C Euphotic zone Microbial loop Particulate organic matter:COP, NOP, POP, d15N HYDRODYNAMIQUE UPWELLING sédimentation Dissolved organic matter COD, NOD, POD Detritical material COP, NOP, POP Deep ocean EXPORT PRODUCTION Conceptual scheme of carbon and nitrogen cycles in the euphotic zone indicating the different nutrient pools (in blue) and biological processes (in red) measured during the BIOSOPE cruise.

  4. OLIGOTROPHY New production and export carbon CO2 CO2 Primary production Dissolved organic matter COD, NOD, POD N2 Nitrite Ammonium Phosphate Silicate Diazotrophy Phytoplankton Trophic chain EXCRETION DO15N/DO13C Euphotic zone Microbial loop Regenerated production Particulate organic matter:COP, NOP, POP, d15N HYDRODYNAMIQUE REGENERATION (NH4, NO3) sédimentation Nitrate Nitrite Ammonium Phosphate Silicate Dissolved organic matter COD, NOD, POD Detritical material COP, NOP, POP Deep ocean EXPORT PRODUCTION Conceptual scheme of carbon and nitrogen cycles in the euphotic zone indicating the different nutrient pools (in blue) and biological processes (in red) measured during the BIOSOPE cruise.

  5. BIOSOPE Parameters • Biogenic elements (C/N/P); POM on 0.2µm • Chlorophyll a • Daily primary production (13C) and new production (15N) • Nitrogen fixation (15N) • Ammonium regeneration and nitrification (15N) • DO15N and DO13C release rates • Variation of natural abundance of 15N (d15N) In red, recent parameters included in our field works (see below)

  6. POOL OF NUTRIENTS Nanomolarlevels (Raimbault al.1990) Nanomolar levels (Holmes et al., 1999) Results from PECHE cruises DYFAMED site Conventional procedures ??)

  7. POOL OF PARTICULATE ORGANIC MATTER Extraction in Methanol (Raimbault et al., 1988) C/N/P on the same sample (Raimbault et al., 1999a)

  8. POOL OF DISSOLVED ORGANIC MATTER CARBON NITROGEN PHOSPHORUS C/N/P on the same sample(Raimbault et al., 1999b)

  9. BIOLOGICAL FLUXES OF CARBON AND NITROGEN 13C/15N2 dual labelling 15N2 fixation Montoya et al., 1996 C-N excretion on the same filtrate(Raimbault et al., 1999c) (Raimbault et al., in progress)

  10. Estimation of nitrogen fixation by the 15N procedure (Montoya et al., 1996) Good reproductibility at low rates Nitrogen fixation is detected in the <10 µm fraction Importance in nitrogen and carbon budgets in oligotrophic systems?? A NEW new production ???? Results from Diapalis cruises

  11. 300 ml + HgCl2 300 ml + HgCl2 Dual Labelling procedure (13C/15N) proposed for the Biosope cruise 13C/15N2 13C/15NO3 0.6-1.2 l samples 13C/15NH4 Incubation (12h/24h) Slawyk et Raimbault., 1995 Raimbault et al., 1999 Raimbault et al., 2000 Slawyk et al., 2000 Filtration Diffusion 1 NH4 regeneration GF/F Diffusion 2 Mass spectrometry Nitrification Diffusion 3 Primary production (x3) New production Regenerated production DON excretion DOC excretion (in progress)

  12. Variation of natural abundance of 15N = d15N It is a non intrusive mean of estimating the degree of N recycling in the photic zone In deep water : d15N = + 6 - 8% Recent N depletion : d15N = + 6 - 13% N2 fixation : d15N = 0 % Persistent oligotrophy : d15N < 0 % Requirements: precision of 0.3‰ PON = 5 µmoles = 70 µg

  13. FIRST TESTS

  14. Additional experiments ??? C/N/P in sediment traps Free floatting net for Trichodesmium Limitation of new production

  15. On board requirements • 1-2 scientists: P. Raimbault + student ??? • Surface of laboratory: 6 m2. • Incubators on the sun deck ( 2 m2) with circulation of surface water. • Sampling before sunset for productivity experiments

  16. NOP and POP measured on GF/F and 0.2µm PTFE membranes in oligotrophic waters

  17. Estimation of primary production by by the 13C procedure POMME MINOS Comparaison of primary production rates obtained with 13C and 14C isotopic procedures

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