We are studying the effect of a pollutant Polybrominated Diphenyl Ethers (PBDEs) on sponge symbiont in terms of microbial community structure and functions. We have sequenced the metagenomic DNA of treated sponge (with abundant symbiotic microbes and other organism inside) and control. Now we are analyze the metagenomic data. The figure showed the abundance of genus from archaea. Blue represent control and yellow represented treated sample. They are all significantly increased or decreased (q<0.05). Can you give some insights from this figure? I noticed that those methogenous archaea generally increased, but what is the possible mechanism and significance to the community?