PhD Thesis at Ifremer: Acquisition of symbiotic partners: modalities and consequences on establishment, distribution and ecology of vent species

PhD Thesis proposal 2019

 ARTEMIS (Acquisition des paRTEnaires syMbIotiqueS : modalités et conséquences sur l’établissement, la distribution et l’écologie d’espèces hydrothermales) : Acquisition of symbiotic partners: modalities and consequences on establishment, distribution and ecology of vent species.

 

Research Unit : Etudes des Ecosystèmes Profonds, Ifremer, Brest (France)

Doctoral School : Sciences de la Mer et du Littoral (SML)

Laboratory : Laboratoire de Microbiologie des Environnements Extrêmes (LM2E)

PhD Supervisor : Marie-Anne Cambon-Bonavita

contact : Marie.Anne.Cambon@ifremer.fr, 02 98 22 47 56

Co-supervisor : Florence Pradillon : Laboratoire Environnement Profond (LEP), Unité Etude des Ecosystèmes Profonds (EEP), Ifremer

contact : Florence.Pradillon@ifremer.fr, 02 98 22 49 57

 

Project summary: The main contributors to hydrothermal ecosystem productivity develop symbiosis with micoorganisms, through which they benefit from local chemosynthesis and get protection from vent fluid toxicity. This partnership is crucial for the development of these animals that are often foundation species for more diverse communities. Several examples of such species that are closely related to each other, and coexist on the same vent sites, but exhibit differences in their symbiotic relashionships (integration level or identity of the microorganism partners) point at the role of these relationships in host micro-distribution and ecology (niche partitionning) with consequences on the functionning of the whole community. In particular, the establishment and the proliferation of symbionts in early life-stages (before and after recruitment) may be a key point of vent communities’ development. This thesis will build on well-studied models in our laboratory: Rimicaris shrimps living on the Mid Atlantic Ridge (Bicose cruises), and Alviniconcha snails from south-west back-arc basins (Futuna 2012 and Chubacarc 2019 cruises). The study will focus on the establishment of the symbiosis during early life-stages of these species. The two models will be compared in order to evaluate the universality of processes between endosymbiosis (Alviniconcha) and ectosymbiosis (Rimicaris).

Key-words: Hydrothermal vents, Rimicaris, Alviniconcha, symbiosis acquisition, recruitment, colonisation

 

Objectives & Approaches: The main objective of this thesis is to better understand symbiosis initiation and proliferation in 5 vent species : Rimicaris spp. (R. exoculata et R. chacei) from the MAR and Alviniconcha snails(A. kojimai, A. boucheti et A. strummeri) from the Wallis and Futuna area. The role of local environmental conditions in symbiotic development of host species as well as consequences on species ecology, particularly mechanisms allowing coexistence will also be analyzed in collaboration with colleagues specialists of vent geochemistry (C. Cathalot, GM Ifremer). Specific objectives are :

  1. To characterize microbial communities associated with post-larval and juvenile stages, in comparison with already described microbiome of adults

  2. To evaluate the influence of environmental conditions on holobiont microdistribution at different life stages;

  3. Assess universality and particular traits in endo- (Alviniconcha) and ecto-symbiosis (Rimicaris).

The project involves imaging approaches (FISH, electronic microscopy, histology and (micro-)CT scan) to characterize the distribution of the main bacterial lineages, describe host morphological modifications due to symbiotic proliferation during development, and identify when the host truly turn into a functional holobiont. Molecular approaches will be used to characterize symbiotic diversity, and functional aspects will be tackled through isotopic and meta-transcriptomic approaches.

 

Expected profile

Master in biology, microbiology, ecology, or biological oceanography with background in marine biology.

Experience in molecular biology techniques (DNA extraction, PCR, in situ hybridization), microscopy and/or bio-informatic analysis of NGS data appreciated.

Interest for multidisciplinary research involving biology, microbiology and geochemistry.

Interest or ability for field work at sea.

Good command of the English language.

Starting date: between October 1st 2019 and December 31st 2019

 

Application:

Deadline : 23/05/2019

Application files and instructions are available here: https://theses.u-bretagneloire.fr/sml/theses-2019

Discipline : SVE; Research Laboratory : Ifremer Brest Laboratoire Environnement Profond

Application file should be prepared as a unique pdf file entitled “Name_Firstname.pdf”, including a curriculum vitae, an application letter, as well as graduation and post-graduation academic records.