Earth’s largest aquifer flows beneath the seafloor, through the rocky upper layer of ocean crust. Together with the sediment that rains down from the ocean above, this vast system is called the marine deep biosphere. It covers the entire seafloor – 70 percent of the planet’s surface. This extreme environment is home to unusual, slow-growing microbes that manage to survive using the limited energy resources available.
“Learning more about microbial populations in the marine deep biosphere is showing us incredible life strategies and redefining our understanding of what it means to be alive,” said Beth Orcutt, a senior research scientist at Bigelow Laboratory for Ocean Sciences. “Our research will help to resolve how life survives under these extreme conditions.”
The hardy microbes that thrive in this environment are isolated from the rays of the sun and limited in oxygen, carbon, and nutrients. This week, Orcutt and her team arrive at the site of a seafloor ocean crust observatory off the coast of Washington with the goal of learning more about the volume, activity, and role that these microbes play in their environment and the ocean beyond. Answering these essential questions will help researchers understand how they affect global environmental cycles and could inform the search for life on other planets.
Orcutt is leading the research team, which is comprised of scientists from 11 institutions, including three postdoctoral researchers and a research associate from Bigelow Laboratory.
The team will also include Kai Ziervogel from the University of New Hampshire and Duane Moser from the Desert Research Institute, who are co-investigators on a five-year project based at Bigelow Laboratory that is developing and applying new tools to connect the functions of individual microbes to their genetic makeup in marine and continental environments.
“This research expedition will provide our collaborative project with key samples from a range of marine environments, including the sunlit surface layer, the deep sea, and the ocean crust,” said Ramunas Stepanauskas, the principal investigator on the project and director of the Single Cell Genomics Center at Bigelow Laboratory.
The researchers will spend two weeks at the eastern flank of the Juan de Fuca Ridge, an underwater volcanic mountain chain where new ocean crust form. A system of subseafloor installations along the ridge flank will provide access to the aquifer fluids circulating more than 900 feet deep within the crust. The team will use the Woods Hole Oceanographic Institution’s deep-diving robot Jason to connect with the seafloor installations and collect samples of the crustal fluids.
While at sea, the researchers will use these fluid samples to conduct experiments that examine microbial activity in this habitat and study the processes that occur beneath the seafloor. Back on land, they will use advanced molecular technologies in the Single Cell Genomics Center to learn more about the activity of individual microbes and the roles they play in the marine deep biosphere.
“Microbial life can survive under conditions that we are not able to replicate in the laboratory,” Orcutt said. “This research will help us understand how these microbial communities interact with their environment and how they have found ways to thrive in unbelievable places.”