Subseafloor sediments harbor over half of all prokaryotic cells on Earth (Whitman et al., 1998). This immense number is calculated from numerous microscopic acridine orange direct counts (AODCs) conducted on sediment cores drilled during the Ocean Drilling Program (ODP) (Parkes et al., 1994, doi:10.1038/371410a0, 2000, doi:10.1007/PL00010971). Because these counts cannot differentiate between living and inactive or even dead cells (Kepner and Pratt, 1994; Morita, 1997), the population size of living microorganisms has recently been enumerated for ODP Leg 201 sediment samples from the equatorial Pacific and the Peru margin using ribosomal ribonucleic acid targeting catalyzed reporter deposition-fluorescence in situ hybridization (CARD-FISH) (Schippers et al., 2005, doi:10.1038/nature03302). A large fraction of the subseafloor prokaryotes were alive, even in very old (16 Ma) and deep (>400 m) sediments. In this study, black shale samples from the Demerara Rise (Erbacher, Mosher, Malone, et al., 2004, doi:10.2973/odp.proc.ir.207.2004) were analyzed using AODC and CARD-FISH to find out if black shales also harbor microorganisms.

Sediment depth is given in mbsf. For prokaryotes and bacteria 0 = not detected. The detection limit was 5 x 104 cells/cm3 for minimum 100 fields of view observed.

Supplement to: Schippers, Axel; Neretin, Lev N (2006): Data report: Microbiological AODC and CARD-FISH analysis of black shale samples from the Demerara Rise, ODP Leg 207. In: Mosher, DC; Erbacher, J; Malone, MJ (eds.) Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 207, 1-6