Our group studies Deep sea chemosynthetic environments, such as hydrothermal vents, hydrocarbon seeps. Sunken wood or whale carcasses are also of interest to us. These remote habitats are caracterized by their patchiness, their elevated biomass, and by peculiar physico-chemical environmental conditions. We study the biology of the endemic species inhabiting such environments, with a particular focus on their dominating symbiotic fauna. Several aspects are studied : the host-symbiont relationship, the sensory organs, the response(s) to thermal, chemical and pression variations. Many of these studies involve experiments on live animals, requiring work at in situ pressure in the lab. Therefore we are also implicated in the design and development of pressurised instruments.
1 - Chemostynthetic symbioses in metazoans
Among the most original symbiotic associations are those involving marine invertebrates and bacteria which perform primary production in the absence of light by oxidizing reduced chemical compounds (chemoautotrophy). They are key to the high biomass productivity observed at many hydrothermal vents, cold seeps and organic falls. Our research focuses on the diversity of microbial symbionts and their hosts, on the functioning of associations at every step of all partner’s life cycle, and on the evolutionary origin and consequences of these complex interactions. Because chemosynthetic symbioses have appeared repeatedly in the course of animal and bacterial evolution, we use comparative approaches and model organisms within the arthropods, mollusks and annelids. We use a wide array of tools including molecular biology, electron and light microscopy, and stable isotope analysis, and perform in vivo experiments during cruises using pressure vessels.
2 - Sensorial perception in hydrothermal shrimp
Hydrothermal vents are relatively ephemeral ecosystems, dependent upon volcanic activity along oceanic ridges and can be highly disparate in their distribution. The capacity to detect and seek out non-natal hydrothermal sites through some level of sensory acuity is critical to the dispersal and survival of this species. Fluid detection probably plays an important role both during larval dispersal and colonization and as adults. Indeed adults, especially Rimicaris exoculata, which must ensure a supply of reduced compounds for their symbionts, requiring some sensory competence for detecting the emissions of vent fluid. Much remains unknown in this regard. Questions could include "what are the signals picked up by animals: temperature, concentration of sulfur, food? What are the receptors involved and where are they located? "
3 - Deep-sea colonisation and adaptation to thermally variable environments: stress response in hydrothermal shrimp
The overall aim of our work is to identify the mechanisms involved in thermal tolerance of deep-sea vent species, and more globally the thermal tolerance processes in thermally variable environments. We have developed comparative studies in shrimp from diverse thermal environments in order to elucidate the thermal adaptations of vent shrimp, as well as the selective role of temperature and pressure in the deep ocean colonization processes.
We are currently focused on the following aims:
4 - Design and development of pressurised instruments : Every 10 meters of water depth, the environmental hydrostatic pressure increases by one atmosphere (0.1 MPa). Deep sea fauna are adapted to high pressure, and the sampling process often proves lethal. Therefore pressure equipment is needed to maintain and study live animals at the lab. Four pressure instruments, were designed in our group :
Caminicella sporogenes gen. nov., sp. nov., a novel thermophilic spore-forming bacterium isolated from an East-Pacific Rise hydrothermal vent. Int J Syst Evol Microbiol 52:1621-8. doi: 10.1099/00207713-52-5-1621(2002)