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Jeudi 11 Juin - The interaction between organic matter and microbes as a carbon sequestration pathway in the ocean

Par semsou — Dernière modification 18/05/2015 17:15
Quand ? Le 11/06/2015,
de 11:00 à 12:00
Où ? Salle Lyot
Participants Mar Benavides, Mediterranean Institute of Oceanography (MIO), IRD Nouméa
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Mar Benavides, Mediterranean Institute of Oceanography (MIO), IRD Nouméa


Titre: The interaction between organic matter and microbes as a carbon sequestration
pathway in the ocean
Résumé: The objective of this seminar is to present my research and myself to the members of the LEGOS laboratory, to exchange ideas and kindly ask them for feedback, with the ultimate aim of promoting my candidature for a CR2 position at IRD (Concours chercheurs 2015).

My previous work has been devoted to investigate biological nitrogen fixation in the ocean. During my PhD at the University of Las Palmas de Gran Canaria (Spain) I investigated the magnitude and controls of nitrogen fixation in the North Atlantic. The results of this research showed that the Northeast Atlantic harbors a contrasted nitrogen-fixing microorganism assemblage as compared to its western counterpart, and that it is strongly influenced by hydrography, nutrient fields and atmospheric deposition. Remarkably, I found that a substantial part of the fixed nitrogen is released out of the cell as organic matter. Marine organic matter is a complex pool of compounds that contains as much carbon as the Earth’s atmosphere in the form of carbon dioxide (CO2). Thus, the dynamics of marine organic matter are bound to have important consequences for global climate. Intrigued by the interactions between organic matter and nitrogen-fixing microbes, during my postdoctoral research I started investigating how organic matter shapes their distribution, activity and diversity in the Southwest Pacific Ocean. The results obtained so far reveal a previously unknown connection between organic matter and nitrogen-fixers in the mesopelagic layer, which suggests that the magnitude of nitrogen fixation is much greater than recognized before and takes place in poorly studied areas of the ocean. This has direct implications in the magnitude of the global ocean nitrogen reservoir, and hence on the biological uptake of CO2 and the capacity of the oceans to regulate climate through biological production.

Firmly convinced to undertake a research career in France, with an international and development perspectives as IRD provides, I have recently applied for a CR2 position. The project proposed for this position aims to study the microbial transformation of organic matter into refractory compounds in the waters around New Caledonia, as a means of CO2 sequestration besides -or complementary to- the classical ‘biological carbon pump’. The interaction between microbes and organic matter is a novel field which requires the application of integrated approaches. I propose a dual approach including organic geochemistry and molecular biology techniques to unveil the role of microbes in transforming organic matter. This approach can be further applied to other ecosystems and specific environmental issues, offering development options in IRD implantations other than New Caledonia, training and education opportunities, as well as bright future research perspectives. Finally, the foreseen integration into the IRD landscape and future research applications will also be presented.

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