So far we’ve heard a lot about the ROV Jason, but not so much about Jason Sylvan, our geomicrobiologist collaborator from University of Southern California. Like many of the members of the science team, Jason is a veteran of several Loihi cruises. The excitement of new discoveries and new tools has kept him interested, and experience has given him a focused approach. He’s here to do 2 things.
Thing #1: investigating nitrogen cycling in hydrothermal environments. Water flowing from hydrothermal vents contains a lot of nitrogen in the form of ammonium. Although a major focus of this cruise has been iron-oxidizing microbes, not all microbes in hydrothermal environments use iron as an energy source; some use ammonium. Ammonium can be traced in the hydrothermal plumes of water rising up over Loihi, which is why Jason is interested in CTD samples collected in the water column, as well as near the vents. “Hydrothermal plumes are sort of like incubators,” he says. He’s running an incubation experiment that involves adding isotopically labeled ammonium to vent and plume water samples, then checking periodically to see how quickly it’s disappearing—or in other words, how quickly the microbes are oxidizing it.
The rate of oxidation indicates how fast the microbes are accumulating, which in turn reveals how much new biological carbon they’re contributing to the deep sea. There’s a broader implication here: a better quantification of carbon production in the deep sea means better-constrained models of the global carbon budget, and thereby perhaps even better-informed models of climate change.
Thing #2: taking a close look at the rocks. One of the robotic arms on the ROV Jason has rock-crushing capabilities, allowing us to snap up chunks of rock and bring them to the surface. Jason (the person) breaks apart some of these rocks for age dating and looks at others under the DEBI-pt, a laser scanner that uses deep UV native fluorescence to detect the presence of microbes at extremely fine scales (tens of nanometers). The DEBI-pt delivers a very exact picture of where microbes colonize rocks, a first step in addressing the question of why we find life where we do. This kind of work is helping to groundtruth the techniques that we could use to look for microbial life on other planets.
–Cat Wolner, NSF
Photo credits: Cat Wolner