Methane and dissolved organic carbon fueled microbial loop supports a tropical subterranean estuary ecosystem

Here we demonstrate that a microbial loop shuttles CH4 and DOC to higher trophic levels of the anchialine food web in the Yucatan Peninsula (Mexico). Methane and DOC production and consumption within the coastal groundwater correspond with a microbial community capable of methanotrophy, heterotrophy and chemoautotrophy, based on characterization by 16S rRNA amplicon sequencing and respiratory quinone composition. This study reveals a heretofore unrecognized subterranean methane sink and contribute to our understanding of the carbon cycle and ecosystem function of karst subterranean estuaries.