Anthropogenic pressures on marine ecosystems and organisms are steadily increasing. Whether and to which extent these pressures influence marine biodiversity is only starting to unveil. Establishment of adequate conservation areas represents a challenging but crucial task in the conservation of genetic diversity and biological variability. Using 16S rRNA gene amplicon sequencing, we analysed the microbial community structure of 32 individuals of the habitat-forming glass sponge Vazella pourtalesii, as well as reference seawater, sediment, and biofilm samples. We assessed how two anthropogenic impacts, i.e. habitat destruction by trawling and artificial substrate provision (moorings made of composite plastic), correspond with in situ V. pourtalesii microbiome variability. In addition, we evaluated the role of two bottom fishery closures in preserving sponge-associated microbial diversity on the Scotian Shelf, Canada.