A new study by researchers at the University of North Carolina at Chapel Hill examined nitrogen fixation among diazotrophs—microorganisms that can convert nitrogen into usable form for other plants and animals—living among sargassum. Sargassum, a brown macroalgae in the seaweed family, floats on the surface of the open ocean and provides habitat for a colorful array of marine life such as small fish, brine shrimp and other microorganisms.
Previous studies have overlooked diazotrophs associated with sargassum, which could mean a historical underestimation of nitrogen fixation in the Atlantic nitrogen budget. The study, published today in PLOS ONE, found that nitrogen fixation in sargassum communities was significant.
“The findings of this study are exciting, especially given much of the recent news regarding sargassum is about the negative effects of its overgrowth in Florida and the Caribbean,” said Lindsay Dubbs, a research associate professor and director of the Outer Banks Field Site at the UNC Institute for the Environment and research associate at East Carolina University’s Coastal Studies Institute. “We were able to show sargassum’s role in nitrogen fixation as meaningful in supporting marine productivity.”
Nitrogen is critical for life. Plants and animals need it for growth. More nitrogen in the ocean means greater biological productivity and growth. Sargassum mats provide an important habitat for organisms to perform nitrogen fixation, but few studies have measured it in sargassum communities.
“Only four studies have been published detailing rates of nitrogen fixation by epiphytes on pelagic sargassum and none in over 30 years,” said Claire Johnson, a Ph.D. student in the Department of Earth, Marine, and Environmental Sciences in the UNC College of Arts and Sciences and a graduate research assistant at the Coastal Studies Institute.
2023-08-04 17:48:02
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