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Laboratoire d'Ecogéochimie des Environnements Benthiques
UMR 8222

proposition de stage M2

Mussel shells as bioarchives for groundwater discharge and fluid seepage in coastal and deep environments.

Description et objectifs scientifiques :
In order to monitor environmental changes and their ecological effects in the coastal and marine environment, the use of carbonate bioarchives is becoming increasingly important worldwide. Long-lived,
slow-growing corals are routinely used as archives to unravel long-term variability of e.g. water temperature, and fast-growing organisms like molluscs can be used to study short-term variability and changes of environmental conditions of their habitat (Lartaud et al., 2010; Nedoncelle et al., 2015).
Hydrological processes play an important role in the life of organisms living both in the coastal and deepsea environment. Input of freshwater from land and the mixing with marine waters modifies the availability of nutrients and growth of calcifying species in the coastal zone. Similarly, input of hydrothermal fluids and
the mixing with deep-sea water control the energy supply and growth of hydrothermal-vent communities. In this project, the use of mollusc shells as bio-archives for (a) groundwater input into coastal lagoons and (b) fluid seepage at hydrothermal vents will be explored.
During carbonate precipitation in calcifying organisms such as foraminiferae, molluscs and corals, elemental and isotopic signatures are embedded into the carbonate matrix which can be used to document environmental conditions experienced by the animal (temperature, primary production etc) as well as life history traits (e.g. growth rate). By sequential sampling along the growth axis, a history of these signatures and of the environmental parameters for which they are a proxy can be established, which will allow us to directly understand (a) exposure of freshwater/fluid seepage to the biota, and (b) to record the variability of environmental parameters such as temperature and salinity, over time scales that cannot easily be obtained with direct measurements.

Encadrants :
Dr. Franck Lartaud (laboratoire d'Ecogéochimie des Environnements Benthiques, LECOB UMR 8222, Banyuls).
Courriel : franck.lartaud @ obs-banyuls.fr
Tél : 04 30 19 24 52


Aladin Andrisoa (Centre de Recherche et d'Enseignement de Géosciences de l'Environnement UMR 7330, Aix-en-Provence).
Courriel : andrisoa @ cerege.fr.
Tél : 04 42 97 15 44


Dr Thomas Stieglitz (Centre de Recherche et d'Enseignement de Géosciences de l'Environnement UMR 7330, Aix-en-Provence)
Courriel : stieglitz@cerege.fr (stieglitz @ cerege.fr)
Tél : 04 42 97 17 61.

 

Localisation du stage :

LECOB UMR822, CNRS UPMC Observatoire Océanologique de Banyuls-Laboratoire Arago, Station Marine de Banyuls-sur-mer (Pyrénées-Orientales). 1, avenue Pierre Fabre, 66650 Banyuls/mer.

22/11/17

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