Differences in the methanogen community between the nearshore and offshore sediments of the South Yellow Sea.

The differences in methanogen abundance and community composition were investigated between nearshore and offshore sediments in the South Yellow Sea (SYS). Shannon, Simpson, and Chao1 indices revealed a higher diversity of methanogens in the nearshore sediments than in the offshore sediments. The Mann-Whitney U test demonstrated that the relative abundance of Methanococcoides was significantly higher in the offshore sediments, while the relative abundances of Methanogenium, Methanosarcina, Methanosaeta, Methanolinea, and Methanomassiliicoccus were significantly higher in the nearshore sediments (P < 0.05). The abundance of the mcrA gene in the nearshore sediments was significantly higher than that in the offshore sediments. Furthermore, a similar vertical distribution of the methanogen and sulfate-reducing bacteria (SRB) abundances was observed in the SYS sediments, implying there is potential cooperation between these two functional microbes in this environment. Finally, total organic carbon (TOC) was significantly correlated with methanogen community composition.