Environment | Search | Science | UW News Blog
January 20, 2022
Although small, microorganisms are the most abundant form of life in the ocean. Marine microbes are responsible for making about half organic carbon usable by life. Many marine microbes live near the surface, relying on the sun’s energy for photosynthesis.
Yet between low supply and high competition for some key nutrients, like nitrogen, in the deep sea, scientists are intrigued by the great diversity of microbial species found there. Researchers from the University of Washington, in collaboration with researchers from 12 other institutions, show that the time of day matters, according to a to study published January 20 in Nature Ecology & Evolution.
The effort began in 2015, when scientists from the Simons Collaboration on Ocean Processes and Ecologya program now co-directed by UW oceanography professor Ginger Armbrustexamined microbes on the surface of the subtropical North Pacific Gyre, the largest expanse of contiguous ocean on Earth.
“[We were interested in] understand how this fluctuation of photosynthesis during the day and its absence at night propagate through the microbial community [in the ocean]“, explained the co-first author Angela Boysen, who did the work as a doctoral student at UW and is now a postdoctoral fellow at the University of Chicago. “This influences the overall functioning of the ecosystem, the amount of carbon stored, the movements of carbon and the way organisms can interact with each other.”
By integrating data on the timeline of metabolic processes of different microbes on the ocean surface throughout the 24-hour light cycle – from transcription of genes of proteins used in metabolism to synthesis of molecules, such as lipids , in the cells of microbes – the researchers found that the coexistence of such diverse microbes may not have been driven by competition, but by the timing of their nitrogen uptake.
With staggered uptake of essential nutrient nitrogen, “instead of having to compete with the whole field, [microbes] only have to compete with organisms that share this specific change with [them]. Maybe that’s a way to dampen the competition a bit and allow all these diverse microbes to live off the same nutrient source,” the co-first author said. Daniel Muratorea doctoral candidate at Georgia Tech.
Thanks to the interdisciplinary team present during the 2015 research cruise, data on almost the entire metabolic process was collected simultaneously from the same water every four hours, giving researchers unprecedented insight into the how metabolic activity differs between these microbes throughout the 24-hour cycle.
“Collecting all these different types of samples…at the same time is really a first way to look at the whole ecosystem at once from all these different perspectives,” Matthew Harkeco-first author and researcher at the Gloucester Marine Genomics Institute.
The data revealed that most activity occurred at four times: dusk (6 p.m.), night (2 a.m.), morning (6 a.m.) and afternoon (between 10 a.m. and 2 p.m.). Although these times are important for many types of microbes, the activities of different groups at each time were not uniform.
“Realizing that various types of microbes acquire nitrogen at different times of day helps answer a long-standing question in oceanography: how can there be such a diversity of life, all essentially in the same place at the same time? ?” said co-author Anitra Ingalls, professor of oceanography at UW. “Being able to explain the underlying reasons for this diversity will help oceanographers better predict how these communities may change as the ocean changes.”
Sacha Coesel, a UW researcher in oceanography, is also a co-author. The research was supported by grants from the Simons Foundation, the National Science Foundation, the Woods Hole Oceanographic Institution, and the US Geological Survey.
A complete list of authors is available with the paper.
This post was adapted from a Press release by Georgia Tech.
Tag(s): Anitra Ingalls • College of the Environment • Oceanography • School of Oceanography • Virginia Armbrust