BATMAN
| Type | Oceanographic cruise |
|---|---|
| Ship | L'Europe |
| Ship owner | Ifremer |
| Dates | 10/03/2016 - 16/03/2016 |
| Chief scientist(s) | SCHINTU JACQUET Stéphanie |
INSTITUT MÉDITERRANÉEN D'OCÉANOLOGIE - UMR 7294 UMR IRD 235 - MARSEILLE 163 avenue de Luminy Bâtiment Méditerranée 13288 Marseille Cedex 9 +33(0)4 86 09 05 00 |
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| DOI | 10.17600/16011100 |
| Objective | The purpose of the BATMAN oceanographic cruise is to study the importance of mineral phases (ballast minerals) associated with particles settling in the water column for remineralization in the mesopelagic zone (100-1000 m) of particulate organic carbon (POC) by marine prokaryotes. The cruise took place from 10 to 16 March 2016 in the North-West Mediterranean on the ANTARES MEUST observation site (FIXO3 OceanSITES, MOOSE EMSO). Our research focused on barium (Ba) tracer dynamics. The biogenic particulate barium (P_Ba, BaSO4 barite) is an estimator of POC remineralization fluxes in the mesopelagic zone. P_Ba was investigated in combination with other parameters related to POC remineralization obtained with different approaches and time scales. The ANTARES MEUST site is an oligotrophic system, where there are significant fluxes of biogenic material and is influenced by recurring deposits of Saharan dust. In view of the notable impacts to come on the ocean linked to climate change, such as acidification of water, changes in biomineralizing species or aerosol deposits, either the abundance or the absence of ballast minerals could have a decisive role in the transfer of matter in the water column. The latter is a crucial question in understanding the role of the ocean in deep carbon sequestration. These modifications could also modify the way in which the dynamics of dissolved and particulate Ba phases operate during POC mineralization processes, which is critical for the validity of the Ba-barite tool to estimate POC remineralization fluxes and their variability in the context of a changing ocean. The 8 scientists involved in the cruise combined their respective expertise in biogeochemistry and microbiology in a joint strategy aiming to better understand the impact of ballast minerals on POC remineralization and their role in regulating the transfer of carbon in the mesopelagic zone. In-situ measurements and sampling were combined on board with experimental incubations performed under controlled pressure (experiment in PASS particle sinking simulator). Indeed, a key point in the methodology was to consider the effect of hydrostatic pressure on remineralization fluxes. Water and particle samples were taken using three methods: with classic Niskin bottles mounted on a Seabird rosette equipped with a "grappe optique" optical profiling package (UVP, LOCP and LISST; MIO atmosphere and sea service) of instruments to characterize particles, with high-pressure bottles (HPSS system) making it possible to sample, incubate and take sub-samples without any risk of decompression or handling of the sampled material, and finally with a Marine Snow catcher (courtesy of R. Lampitt, UK, Southhampton) which enabled the harvesting of material, part of which will be used for the PASS experiments. The cruise fits into the national LEFE-CYBER and international GEOTRACES, IMBER and SOLAS themes, and is directly linked to the Mediterranean MISTRALS programme, including the MERMEX project's WP2 actions. The cruise is related to the OT-MED ROBIN project whose general objective is to study how organic/mineral interactions affect the mesopelagic remineralization of POC by marine prokaryotes, to better constrain estimations of C transfer in the water column in the context of environmental change. |