Bathymodioline mussels of the Mediterranean Sea: connectivity among chemosynthetic habitats

Symbiotic association between deep-sea marine invertebrate and chemosynthetic bacteria has been considered has a key adaptation allowing colonization of chemosynthetic habitats. Remarkably, this kind of symbiosis was discovered in a lot of other environments such as coastal sediments, mangroves and continental margins. To improve our knowledge about host connectivity, the chemosynthetic deep-sea mussels (Bivalvia, Bathymodiolinae) are a great model because they occur worldwide and including ubiquist species able to colonize various chemosynthetic habitats in a wide range of depth. Whereas biological data pile up for the giant mussels, the small mussels remain poorly studied because difficult to sample. For this reason, some wood experimental devices have been deployed in the Western part of the Mediterranean Sea to better assess the connectivity of deep-sea mussels and there symbionts. In combination to fauna colonization, the experimentally immersed wood was dedicated to microbial and chemical study centered on wood degradation and sulfur dynamics. During the last three campaigns of recuperation of experimental devices, mussel populations have been collected. Two species, genetically divergent, were highlighted from a phylogenetic analysis performed with a mitochondrial and a nuclear gene (COI and rRNA 28S) corresponding to the species known from the Eastern part of the Mediterranean Sea from seep sites, Idas modiolaeformis and Nipamodiolus simpsoni. For these two species, the bacterial diversity was assessed based on the 16 rRNA gene and data were compared with those available in literature. Our study of the bacterial diversity allowed detecting thiotrophic symbionts and other bacteria close to those identified in bathymodioline species from the Mediterranean Sea and the Gulf of Cadiz. However, the bacterial diversity is much contrasted between the two species. The first one, I. modiolaeformis, displays various phylotypes whereas only one phylotype was detected in the second one, N. simpsoni. Connectivity patterns are also contrasted for these two species. Indeed, whereas populations of I. modiolaeformis are genetically structured, no significant geographical structure was detected for N. simpsoni. These striking differences could be attributed to different life history strategies.

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First Name: 
Justine
Last Name: 
Thubaut
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+33 1 40 79 37 43
Affiliation: 
Muséum National d'Histoire Naturelle de Paris
First Name: 
Nadine
Last Name: 
Le Bris
Affiliation: 
Université Pierre et Marie Curie-Paris 6
First Name: 
Sarah
Last Name: 
Samadi
Affiliation: 
Muséum National d'Histoire Naturelle de Paris
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Distribution and abundance
Ecological Interactions
Abstract ID: 
CBE5-160