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Limitations and controls of nitrogen fixing microbes in coastal North Atlantic

Wednesday, October 21, 2026 at 12:30pm to 1:30pm

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SMAST East 101-103 : 836 S. Rodney French Boulevard, New Bedford MA 02744
Callie Rumbut
c.rumbut@umassd.edu
https://umassd.zoom.us/j/97440069270

Seminar Announcement
Department of Estuarine and Ocean Sciences

"Limitations and controls of nitrogen fixing microbes in coastal North Atlantic"
Dr. Pia Moisander
Professor, Biology and Estuarine and Ocean Sciences, UMassD

Wednesday, October 21, 2026
12:30 - 1:30 pm
SMAST E 101-103 and via Zoom

Abstract:

Biological nitrogen fixation is an assimilatory process in which certain bacteria and archaea (diazotrophs) reduce dinitrogen gas to biologically available ammonia. The process is important in marine environments where nitrogen limitation prevails. Classically, nitrogen fixation in marine environments has been attributed to cyanobacteria, but recent research shows a great diversity and prevalence of non-cyanobacterial diazotrophs (NCDs). The environmental controls and limitations of marine diazotrophs remain elusive.

In this talk I will discuss our recent studies on diversity and environmental limitations of cyanobacterial and non-cyanobacterial diazotrophs in coastal New England. I will first discuss characterization and phosphorus limitation in a benthic, bloom-forming cyanobacterial diazotroph Hydrocoleum sp. on Nantucket Island. I will then discuss diazotroph distributions in Buzzards Bay over a decadal scale, demonstrating seasonal filtering of communities, largely driven by the prevalence and seasonal variability in the cyanobacterial UCYN-A. Finally, I'll discuss potential metabolic strategies of NCDs based on metagenome assembled genomes we've enriched from Buzzards Bay. Understanding the environmental controls and limitations of marine nitrogen fixing microbial communities allows assessment of their importance in the global nitrogen cycle.

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https://umassd.zoom.us/j/97440069270
Note: Meeting ID and passcode required, email contact to obtain

For additional information, please contact Callie Rumbut at c.rumbut@umassd.edu