Factors shaping the microbiomes of deep-sea sponges

Ieva Čaraitė

Marine sponges are filter-feeding metazoans that host complex microbiota and can be found widely spread from polar regions to tropics and from shallow to deep waters. They are great organisms for studying marine symbiosis, as they are the oldest still existing metazoans and live in strong association with microorganisms. There are more studies conducted on shallow water sponges due to their better accessibility, so their microbiome is more explored than that of deep-sea sponges. In order to obtain a better understanding of symbiont community compositions in Arctic deep-sea sponges, research was conducted on specimens collected at Vesteris Seamount during cruise MSM86 of RV Maria S. Merian in 2019 August/September. The last exploration of that area was 30 years ago the microbial communities associated with the sponges were not studied. In the present work, 104 sponge samples corresponding to Demospongiae and Hexactinellida classes and 18 reference samples (water, sediments) were analyzed via 16S rRNA gene amplicon sequencing. Three factors were implemented into the analysis to estimate the main driver shaping symbiont communities: host-identities, shape and facies. This study brings new insights into the composition of deep-sea sponge microbial communities of a variety of hosts.