Biology subjects

Cathalot, C.

Publications and source records attributed to Cathalot, C..

3 recordsLinked to original sources

bioRxiv2026

Two new gastropod holobionts from Atlantic hydrothermal vents showing different levels of endosymbiosis dependence

Chemosynthetic symbioses underpin animal life at deep-sea hydrothermal vents, encompassing substantial variabilities in symbiont identity, metabolic capacity, and host dependence. Here, we characterise symbioses in two peltospirid snails from Mid-Atlantic Ridge vents, Peltospira gargantua and P. smaragdina, using 3D anatomical reconstruction, stable isotope analyses, fluorescence in situ hybridization, transmission electron microscopy, and metagenomics. Both species hosted abundant intracellular Campylobacterota within bacteriocytes of a hypertrophied oesophageal gland. Their dominant symbionts belonged to genus Sulfurimonas, but the two hosts were associated with distinct symbiont lineages. Symbiont genomes encoded carbon fixation through the rTCA cycle, sulfide oxidation, and Group I Ni-Fe hydrogenases, indicating combined thiotrophic and hydrogenotrophic capacities. Hydrogenase copy number varied across vent fields from one to three copies. The P. gargantua symbiont from the hydrogen-enriched Hydra vent field carried two divergent copies, including one with a truncated catalytic region, potentially reflecting local adaptation to vent geochemistry. Anatomical and isotopic comparisons further revealed contrasting host dependence, with P. gargantua having a proportionally larger oesophageal gland and ventricle coupled with a reduced radula, as well as a greater nitrogen-isotope enrichment between symbiotic and non-symbiotic tissues. The smaller oesophageal gland and larger feeding apparatus of P. smaragdina point to it being mixotrophic. Previously, all known peltospirid symbioses have partnered with Gammaproteobacteria, and we expand the known diversity of peltospirid symbioses. Our findings underscore how closely related hosts can exhibit different degrees of dependence on symbiosis, and that mixotrophic symbiosis may be prevalent in small vent species previously thought to be non-symbiotic.

ecology↗

bioRxiv2023

A step towards measuring connectivity in the deep-sea: elemental fingerprints of mollusk larval shells discriminate hydrothermal sites

Deep-sea hydrothermal-vent systems are under investigation for base and precious metal exploitations. The impact of mining will depend critically on the ability of larval dispersal to connect and replenish endemic populations. However, assessing connectivity is extremely challenging, especially in the deep sea. Here, we investigate the potential of elemental fingerprinting of mollusc larval shells to discriminate larval origins between multiple hydrothermal sites in the Southwest Pacific Ocean. The gastropod Shinkailepas tollmanni represents a suitable candidate as it uses capsules to hold larvae before dispersal, which facilitates sampling and ensures mineralization occurs on the site of origin. Multielemental microchemistry was performed using cutting-edge femtosecond laser ablation Inductively Coupled Plasma Mass Spectrometry analysis to obtain individual measurements on 600 encapsulated larval shells. We used classification methods to discriminate the origin of individuals from 14 hydrothermal sites spanning over 3,500 km, with an overall success rate of 70%. When considering less sites within more restricted areas, reflecting dispersal distances reported by genetic and modelling approaches, the success rate increased up to 86%. We conclude that individual larval shells register site-specific elemental signatures that can be used to assess their origin. These results open new perspectives to get direct estimates on population connectivity from the geochemistry of pre-dispersal shell of recently settled juveniles.

ecology↗

bioRxiv2021

Population structure and environmental niches of Rimicaris shrimps from the Mid Atlantic Ridge

Among the endemic and specialized fauna from hydrothermal vents, Rimicaris shrimp surely constitutes one of the most important and emblematic components of these ecosystems. In the Mid Atlantic Ridge, two species affiliated to this genus co-occur: Rimicaris exoculata and Rimicaris chacei that differ by their morphology, their trophic regime as well as by their abundance. The first forms large and dense aggregations on active vent chimney walls in close proximity to vent fluid emissions, whereas the second is recognized as much less conspicuous, living mostly in scattered groups or solitary further away from the fluids. However, the recent revision of Rimicaris juvenile stages from the Mid Atlantic Ridge shows that R. chacei abundance would be higher than expected at these early life stages. Here, we describe and compare the population structures of R. exoculata and R. chacei at the Snake Pit and TAG vent fields. We show distinct population demographics between the two co-occurring shrimps with a large post settlement collapse in R. chacei population suggesting a large juvenile mortality for this species. We also observe important spatial segregation patterns between the two species and their different life stages. Additionally, our results highlight distinct niches for the earliest juvenile stages of both R. exoculata and R. chacei, compared to all the other life stages. Finally, we discuss the potential factors - predation and competitive interactions among others - that could explain the differences we observe in the population structure of these two species.

ecology↗