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>>>> Hypotheses & objectives |
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Hypotheses: 1) Increase in hydrostatic pressure conditions alters bacterial mineralization rates and slows down the decomposition of particle during their fall throughout the water column. This affects (a) the quality of DOM released into the seawater, thus modifying the growth of pelagic bacteria, and (b) the dissolution rate of mineral ballasts (silicate, carbonate and dust). Dissolution of mineral ballast would affect the sinking rate of particles. 2) Hydrostatic pressure condition alters the species composition of prokaryotes communities associated with sinking particles. This succession in microbial communities alters biogeochemical processes exerted by prokaryotes on the particles. This affects mineralization processes throughout intermediate and deep-sea water masses, and the pelagic-benthos coupling, and thus the flux and the quality of organic inputs for intermediate, deep-sea and benthic microbial communities.
Objectives: 1) To quantify effects of increasing hydrostatic pressure on microbiological processes of organic matter mineralization (POC DOC transformation) and regeneration of biogenic elements (silicates, carbonates) within intermediate and deep-sea waters. These biogeochemical processes affect organic inputs throughout the intermediate and deep-sea water masses and the coupling between the pelagic zone and the benthos.2) To determine effects of hydrostatic pressure on prokaryotic species composition ( Bacteria and Archaea) using DGGE (or T-RFLP) and FISH during sinking simulation experiments and in "neutrally buoyant floc" (atmospheric pressure) experiments.3) To study effects of hydrostatic pressure on the dynamics of prokaryotic community composition and activities. The microbial "black box" should not be regarded as homogeneous. Micro-FISH method breaks down this black box with fluorescent 16S rRNA probes and simultaneously determines DOM uptake by each prokaryotic subgroup. |
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Contact:
Christian Tamburini (tamburini@univmed.fr)
; Tel.: +33 4 91 82 90 53 - Fax : +33 4 91 82
90 51 |
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© 2003-2009 - Laboratoire de Microbiologie, Géochimie et Ecologie Marines
- Last update: April 20th 2006 |