Microbial epibiotic community of the galatheid squat lobster Munidopsis alvisca

The basis for life at hydrothermal vent sites is provided by chemosynthetic primary producers that provide substrates for heterotrophic microorganisms and generate biomass for higher trophic levels. Chemoautotrophs are often found in association with invertebrates that provide a stable habitat and in turn benefit from detoxification of hydrothermal vent fluids. To investigate attached bacterial and archaeal communities on deep-sea squat lobsters, we collected Munidopsis alvisca specimens at the hydrothermal vent site Rebecca's Roost (Guaymas Basin, Mexico). Amplicon sequencing revealed that epibiotic communities were significantly different from ambient sea water communities. Major bacterial taxa on M. alvisca carapaces were chemoautotrophic Gammaproteobacteria, such as Thiotrichaceae and Methylococcaceae, while archaea were almost exclusively represented by ASVs affiliated with Ca. Nitrosopumilus. In sea water samples marine group II and III archaea and organoheterotrophic Alphaproteobacteria, Flavobacteriia and Planctomycetacia were more abundant and more active. We assume that main metabolic processes, carried out by M. alvisca epibiota, are ammonia, methane, and sulphide oxidation, while free-living heterotrophic bacteria degrade hydrocarbon-rich compounds and sinking organic matter. A mutualistic host-microbe relationship is likely, considering that M. alvisca benefit from sulphide detoxification by their epibiota, while attached microbes are supplied with a stable habitat in proximity to substrate-rich hydrothermal fluids