Sediments were collected using multicore sampler, or simple cores when a submarine or a remote operated vehicle (ROV) were present. The cores were collected and sliced according to sediment depth and using a standardized scheme. Slices were preserved and treated individually. When hard substrate was collected, the gear ELFES designed on purpose to scratch and collect the surface of substrate, or bulk samples were retained after sieving communities. Nucleic acids (DNA or RNA) were extracted and submitted to a PCR-ligation protocols using 6 sets of primers pairs targeting metazoans (2 primer pairs targeting a fragment of Cytochrome Oxydase I and one of rDNA18S V1-V2), microeukaryotes (2 primer pairs targeting rDNA 18S V4 and V9) and prokaryotes (2 sets of primer pairs targeting rDNA16S V4-V5 respectively defined for prokaryotes in general, and archaebacterial in particular).