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Reference : UMR7263-CARJUL-004
Workplace : MARSEILLE 07
Date of publication : Friday, September 11, 2020
Scientific Responsible name : PEREZ Thierry
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 1 November 2020
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly
Description of the thesis topic
Mitigating the effects of global change on socio-ecosystems and protecting biodiversity are major challenges for the decades to come. Ecosystem services provided to humanity are powerful communication tools that should convince as many people as possible of the need to conserve nature. The ocean concentrates most of the environmental disturbances and appears to be the compartment that would contain the greatest regulatory potential. Knowledge about the functioning of ocean ecosystems and their services is still scarce, paradoxically.
Since its beginning, LIA MARRIO has focused on studying all the components of sponge biodiversity. These sessile filter-feeding organisms dominate many ecosystems and play a key role in the cycle of matter in the ocean. Excellent bioindicators, they are less known for their ability to transform and degrade pollutants than for their production of molecules with pharmacological properties. Sponges are, thus, a potential source of ecosystem services, some of which still need to be revealed. MARRIO has shown for the first time that sponges are able to exude molecules constituting signals in a complex "chemical seascape", and thus interacting from a distance with the mobile fauna of a marine ecosystem. This type of chemical signal conditions the relationships between organisms and the environment, and therefore intervenes in the general functioning of ecosystems. These chemical signals contribute to functions related to mediation and other ecosystem services; the importance of which can be compared to the terrestrial volatile signals associated with odors and their role in the relationships between plants and insects. Unfortunately, marine chemical ecology has long focused on the pharmacological potential of sponges, forgetting the greater portion of chemical diversity and its ecological functions. Also, MARRIO has developed metabolomics in marine ecology, considering chemical diversity as an indicator of the effects of natural selection or as a tool for measuring biological responses to global change. The priority today is to better understand the ecological functions of chemical compounds produced by marine organisms. With its development project in IRL, MARRIO has the ambition to develop new tools for the underwater “capture of chemical seascapes” and to experimentally study their functions at the ecosystem scale: (I) identify the chemical cues emitted by sponges and governing mediation in a marine ecosystem; (II) measure the influence of chemical signals on swimming organisms, from the expression of chemoreceptor genes to their behavioral response; (III) complete the functioning models of marine ecosystems.
Ultimately, this interdisciplinary project will enable to measure the effects of changes in biodiversity (e.g. of sponges associated with climatic events, introductions or pollution) on chemical seascapes and marine ecosystems. It will demonstrate the key role of chemical mediation in the ocean, a function as essential as pollination in continental environments. It will then be possible to better communicate on ecosystem services and the need to protect marine biodiversity in a context of a changing environment.
The host laboratory will be the IMBE (Mediterranean Institute of Biodiversity and Marine and Continental Ecology, UMR 7263 CNRS, Aix Marseille University, IRD, Avignon University). More specifically, the doctoral student will be attached to the DFME team located in Marseille. The recruited agent will carry out her/his PhD training within the framework of the MUSE project "Chemical mediation in the marine environment, an invaluable source of Ecosystem Services". The aim is to develop new tools for underwater “capture of chemical seascapes” and to experimentally study their functions on an ecosystem scale: (I) identify the chemical signals emitted by sponges and governing chemical mediation in a marine ecosystem; (II) measure the influence of chemical signals on swimming organisms; (III) complete the functioning models of marine ecosystems.
Available Resources: IMBE joint research services and technical platforms, including chemical and metabolomic ecology service, molecular biology service, aquariums. OSU Pythéas Institute Marine Services.
Main contacts: Thierry Pérez, Charlotte Simmler and the "diversity and functioning of molecules in ecosystems" team in particular. Other IMBE staff, in particular those responsible for technical services. Scientific collaborators of LIA MARRIO France Brazil.
Constraints and risks
Working conditions: 35 hrs / week minimum - missions at sea, in France and abroad.
Expected skills: strong background in ecology and chemistry; practical experience in one of the disciplines and in Omics data processing. Autonomy, sense of initiative and team spirit. An aptitude for work at sea, in particular Scuba diving, will be appreciated.
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