BEATE SLABY: Exploring the sponge microbiota of Langseth Ridge as part of the H2020 EU project SponGES

Exploring the sponge microbiota of Langseth Ridge as part of the H2020 EU projectSponGES

The Horizon 2020 EU project SponGES aims at developing an integrated ecosystem-basedapproach to preserve and sustainably use deep-sea sponge ecosystems of the North Atlantic.One amongst several SponGES-related cruiseswas RV Polarstern cruise PS101 to theCentral Arctic Langseth Ridge. Here the demospongeGeodia parvawas found to dominatethe summits of three adjacent seamounts: Karasik seamount and the newly discoveredCentral mount and Northern mount, as wellas the saddle between Karasik and Centralmount. In their megafaunal community composition, the different sites appeared to besimilar, but differences in density and relative abundances were apparent during Ocean FloorObservation System (OFOS) transects.

Thus, our main research questions are: Are theredifferences also in the sponge microbiota? How are the microbes involved in the sponges’nutrition? Which roles do the different microbes play in the system? By 16S rRNA geneamplicon sequencing, differences in sponge microbial community composition wereaddressed and the sponge microbiota were compared to those of associated seawater andsediment. While the demosponges contained very similar microbial communities with nosignificant differences between habitats or host species, the sponge microbiota were clearlydifferent from surrounding seawater and sediment references.

A high-resolutionmetagenomic and metatranscriptomic study of the dominantGeodia parvawas conducted toassess the functional role of the sponge microbiome and to discover possible differencesbetween the habitats. Taking into account the large sponge biomass at Langseth Ridge, themicrobial involvement in nutrient turnover could affect the sponge host and consequently,also have cascading effects on the sponge grounds ecosystem.