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This WP will provide technological means for studying
the organisms inhabiting extreme ecosystems. These means will allow the
investigation, through experiments on live organisms, of the
physico-chemical limits suitable for life. In addition to improve our
understanding of organism/environment relationships, these experiments
will help gathering crucial information on native biological
characteristics of these organisms (thermotolerance, adaptation to anoxic
conditions). Two approaches are proposed : the first one is to collect and
recover live macrofauna in good physiological state, in order to carry out
in vivo experimentations in controlled environmental conditions; the
second is to monitor in situ environmental conditions associated to the
development of microorganisms inside experimental colonisation devices.
Microorganisms
Hot vent and cold seep chemosynthetic ecosystems
represent oases in the sparsely populated deep sea. Both represent complex
systems where biology and geology directly interact. Although they have
been already discovered in the 70's, we are still far from understanding
their nature, distribution and interaction with the surrounding deep sea
ecosystem.
From recent investigations of cold seep systems we
learned that their biogeochemistry is very heterogeneous on all scales
in space and time. Look at the differences in microbial activity of
sediment cores taken within an area of 0.25 m2 in Figure 1.
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Figure 1. Methanotrophic sulfate
reduction rates of samples taken by a multiple corer within an area of
ca. 0.25m2 at Hydrate Ridge, Cascadian Margin. Each symbol represents
a different replicate core. From: Treude et al. 2003, Marine Ecology
Progress Series 264, 1-14.
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Figure 2. ROV Victor 6000 (IFREMER)
subsampling bacterial mats surrounding the Haakon Mosby mud volcano
(joint AWI/IFREMER expedition 2001). |
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The reason for this may be varying gas and fluid
fluxes causing varying turnover rates of methane and sulfate. However,
changes in the activity of seep fauna and geological interferences as
illustrated in Fig. 3 may be equally important. A major methodical
problem of investigations at vents/seeps is the measurement of in situ
microbial activity and distribution. Samples recovered from greater
depths undergo decompression and therefore often strong degassing and
mixing. |
Figure 3. Possible reasons causing
heterogeneity in microbial turnover rates at cold seep sites covered
by sulfur-oxidizing bacteria and symbiotic bivalves. From: Treude et
al. 2003, Marine Ecology Progress Series 264, 1-14. |
It is therefore one aim within WP4 to develop
instrumentations that allow a better understanding of endemic organisms of
seeps and vents.
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PERISCOP (Projet d’Enceinte de
Récupération Isobare au Service de la Collecte d’Organismes Profonds) will
allow the collection and recovery of deep-sea organisms at their natural
pressure (isobaric collection), from depths up to 3000 m. It will give
access to live animals or bacteria, by avoiding the traumatic, and often
lethal, decompression. |
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DESEARES (DEep-SEA RESpirometer)
will allow us to understand, with a high level of resolution and using an
ecophysiological approach, the physiological mechanisms, responsible for
the life and evolution of the key organisms colonizing extreme marine
habitats. |
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AISICS (Autonomous In Situ
Instrumented Colonisation System) will allow in situ colonisation of
a specific substratum by indigenous microorganisms and will simultaneously
provide information on temperatures and fluid composition inside the
colonisation system.
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