Bacteria and microbes in underwater cave feed on methane

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Bacteria and microbes in underwater cave feed on methane

November 29, 2017 - 18:25
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Researchers have discovered that methane from surface vegetation is an important food source for bacteria and microbes in the underwater cave network in Mexico's Yucatan Peninsula.

Cave explorer Bil Phillips, also a member of the Texas A&M-led team, uses a flashlight and line to navigate the underwater cave.

When exploring the underwater flooded cave passages within the Ox Bel Ha cave network in Mexico’s Yucatan Peninsula, researchers discovered that methane is an important food source for the bacteria and other microbes there; in fact, they are the foundation of a food web within the cave system.

Their discovery forms the basis of a paper published in the current issue of the Nature Communications journal.

The team responsible for the discovery comprises David Brankovits, a student from Budapest, Hungary (who led the research for his PhD at Texas A&M-Galveston University), and researchers from Mexico, The Netherlands, Switzerland, the University of Alaska-Fairbanks and the US Geological Survey.

The methane in the cave originates from surface vegetation above. It seeps through the limestone in deep waters of the cave system. The microbes then consume the methane in the water and other dissolved organic material produced in the overlying soils and permeable carbonate rock.

“In the studied system, cave-adapted organisms exist where there is no sunlight and virtually all food sources are present in dissolved forms. Without the presence of microbes that can utilise methane and other dissolved energy sources, these animals could not live otherwise,” said Brankovits.

For the researchers, the next step is to investigate other similar cave systems in the Bahamas, the Dominican Republic and other Caribbean locations. According to Brankovits, “There are other dissolved organic materials like natural acids and alcohols, down there that we are just now learning about, and we need to explore them in more detail. The results could be surprising.”

Tom Iliffe, professor of marine biology at the university said that providing a model for the basic function of this globally-distributed ecosystem was an important contribution to coastal groundwater ecology. He added that it “establishes a baseline for evaluating how sea level rise, seaside touristic development and other stressors will impact the viability of these lightless, food-poor systems."

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