During R/V Sonne cruise SO254, we conducted ex-situ experiments with shallow- and deep-water demo- and hexactinellid sponges from New Zealand. Over a period of 5 hours, the sponges were incubated at in-situ temperature in the light (shallow-water incubation) or in the dark (deep-water incubation), and water samples for dissolved organic carbon (DOC), total dissolved nitrogen (TDN), and fluorescing dissolved organic matter (FDOM) were taken every hour. At the end of the incubations, samples for (biogeochemical) tissue analyses (including fatty acid analyses) were taken of the sponges together with samples for microbial analyses of the bacterial community living inside the sponges. Bacteria community composition of 4 species (number of replicates per species: 1) were analyzed based on DNA extracted from sub-samples taken from the sponges at the end of the incubations. After sequencing, representative amplicon sequence variants (ASVs) were classified taxonomically with the SILVA database.