Large freshwater aquifers can be found under the porous crust of Earth’s oceans. Though it has been difficult to obtain aquifer samples for study without contaminating the sample or the source with the ocean’s saltwater, it has been predicted that they contain as much as 1/3 of the world’s biomass. A new study into these aquifers has revealed a new species of microbes that could be influencing the carbon cycle. Alberto Robador of the NASA Astrobiology Institute in Hawaii was lead author of the open access paper, which was published in Frontiers in Microbiology.
“It was surprising to find new bugs, but when we go to warmer, relatively old and isolated fluids, we find a unique microbial community,” Robador said in a press release.
The study was partially funded by the NSF’s Center for Dark Energy Biosphere Investigations (C-DEBI). Using these resources, the team explored the biodiversity of microbes in the deep ocean. The samples came from an aquifer located under 3.2 kilometers (2 miles) of ocean water and over 150 meters (500 feet) of seafloor.
“Trying to take a sample of aquifer water without contaminating it with regular ocean water presented a huge challenge,” added co-author Jan Amend, Director of C-DEBI.
This problem was solved by the aptly-named CORK observatories, which stands for Circulation Obviation Retrofit Kit. These create a seal on the ocean floor, allowing the researchers to drill through the sediment and into the aquifer to collect samples without mixing ocean water with the sample or allowing the saltwater to reach the aquifer, which would have tainted the entire water reserve.
The microbes discovered by Robador’s team have not yet been officially classified, but it is known that they are able to ‘breathe’ sulfate; a salt that has a wide variety of industrial uses. These microbes use a form of anaerobic respiration which allows them to obtain energy by using organic compounds from decaying organisms to reduce the sulfate.
This could be an important factor in the planet’s carbon cycle. As the microbes respire using sulfate, carbon dioxide is released as a byproduct. Carbon dioxide is necessary for plants when performing photosynthesis, which converts it into oxygen. This delicate cycle has been interrupted by the massive quantities of carbon dioxide and other greenhouse gasses put into the atmosphere by humans.
“This is the first direct account of microbial activity in these type of environments,” Robador added, “and shows the potential of these organisms to respire organic carbon.”
Understanding the full carbon dioxide contribution of these sulfate-breathing microbes could help scientists improve climate models.
Check out this video that explains how CORK observatories are installed: