Nitrogen is essential to marine life and cycles throughout the ocean in a delicately balanced system. Living organisms—especially marine plants called phytoplankton—require nitrogen in processes such as photosynthesis. In turn, phytoplankton growth takes up carbon dioxide from the atmosphere and helps regulate global climate.
According to new research by Thomas Weber, an assistant professor of Earth and environmental sciences at the University of Rochester, small microenvironments in the deep ocean may hold key clues to the global cycling of nitrogen in seawater.
In a paper published in Nature Geoscience, Weber and his co-author Daniele Bianchi, an assistant professor of atmospheric and oceanic sciences at UCLA, show that small microbes that remove nitrogen from the water exist in these microenvironments and are more widespread than previously thought. Using this data, they developed a computer model that changes the way we think about the marine nitrogen cycle.
“The previous understanding of the nitrogen cycle was that nitrogen was lost from the ocean only in three regions where oxygen is scarce. If we wanted to predict how the nitrogen cycle would respond to climate change, all we needed to do was predict how these three low oxygen regions would expand or contract,” Weber says. “Our study changes that picture by showing that nitrogen loss is actually happening over much larger regions, and we need to think about how the ocean as a whole is changing.”
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Image: There are three regions in the ocean with exceptionally low oxygen levels; two off the coast of the Americas, just north and south of the equator (numbers 1 and 2) and one in the Arabian Sea (number 3). These areas are known as "dead zones" because only anaerobic microbes can survive here. (Credit: Thomas Weber / University of Rochester)