Nitrogen! This simple element controls so much about life in the ocean and therefore Earth’s climate as a whole. Much of the ocean’s fertility is limited by nitrogen – an essential ingredient for making DNA and proteins – so in in many ways, the availability of this nutrient sets the concentration of greenhouse gases like carbon dioxide in the atmosphere. In other words, climate is all about nitrogen

Phytoplankton (the microscopic plants that form the base of the marine food chain that directly control carbon dioxide levels) are not the only consumers of nitrogen in the ocean. Certain groups of bacteria known as “denitrifiers” also consume this nutrient, but in contrast to phytoplankton, they do not also draw down atmospheric carbon dioxide. Furthermore, these denitrifiers convert nitrogen to a molecular form not accessible to most other life and therefore prevent phytoplankton from growing. One caveat: denitrifiers are not “bad” by limiting the fertility of the ocean. They are natural and serve essential roles in the climate system. My research attempts to understand what controls these organisms and how in turn they help shape the climate of the planet.

As for who these denitrifiers are: that’s a tough question, and the reason I have a job. My goal on this cruise is to understand which microbes are responsible for consuming nitrogen, and how these organisms structures themselves to form an efficient (or not) community. By sampling for DNA at a variety of conditions (namely dissolved oxygen concentrations) found along the southern California coast, we can begin to evaluate how nitrogen is transformed in the environment, who is doing it, and how fast it is happening.

The ultimate beauty in doing what I do is that it necessarily requires me to go to sea to sample the natural environment because none of the great complexity of life observed in the ocean can be reproduced synthetically in the laboratory. While at sea, I am exposed to the sensational nature of the world around me: gorgeous sunsets, gallivanting whales, and awesome new friendships with the other scientists and crew on board.

Photo credit: Chris Lowery

Posted by Andrew