Box plots of richness, diversity and abundance for the Archaea, methanogens, Crenarchaeota and MBG-D.

The three layers were discriminated from TTGE profile analyses. a, b, c indicate significant differences (p<0.05). Richness and diversity were calculated from the number and the relative peak area of bands on TTGE profiles. Average abundances were determined from 16S rDNA q-PCR data. The abundance of the methanogens was estimated by addition of the abundance of Methanosaetaceae and Methanomicrobiales. All the data were obtained on sediment core 1.