Earth System Science Seminar Series: Dr. Jenan Kharbush

EARTH SYSTEM SCIENCE
SEMINAR SERIES

November 12, 2026
12:00 - 1:00 PM
Y2E2, Room 299


Jenan Kharbush, Ph.D.
Assistant Professor
University of Michigan

 

“A moving nitrogen target: How nitrogen availability and speciation shape the ecology of Microcystis-dominated cyanobacterial blooms” 

Abstract
In cyanobacterial harmful algal blooms (CyanoHABs) dominated by the non-diazotrophic cyanobacterium Microcystis, nitrogen availability is critical for production of the nitrogen-rich toxin microcystin, and may also play a role in shaping Microcystis strain composition and relative abundance of toxic and non-toxic strains. During the annual CyanoHAB in Western Lake Erie, the dominant nitrogen pools shift between inorganic and organic forms as the bloom progresses. At the same time, Microcystis strain composition and the heterotrophic bacterial communities associated with Microcystis colonies also change. Recent metagenomics and culture-based work suggests that some of these heterotrophs participate in nitrogen acquisition and cycling processes with Microcystis. In this talk, I will discuss our efforts to understand the influence of nitrogen availability and speciation on Microcystis bloom ecology using nano-secondary ion mass spectrometry (nanoSIMS), complemented by shotgun metagenomic and transcriptomic community data. Our results suggest that Microcystis maintains a broad capacity to assimilate multiple nitrogen substrates across all bloom phases, effectively remaining primed to exploit shifting nitrogen pools regardless of their ambient concentrations. This flexibility may help sustain Microcystis dominance under changing bloom conditions.

 

Biography
I am an Assistant Professor in the Earth and Environmental Sciences Department at the University of Michigan. I earned my PhD in Chemical Oceanography from the Scripps Institution of Oceanography in San Diego, CA, where I first developed an appreciation for the complexity of microbial life and the outsized impacts microbes have on their environment. At U-M, my research group studies how aquatic microorganisms, particularly phytoplankton, acquire and use nitrogen, including during cyanobacterial harmful algal blooms. The lab combines laboratory culture experiments with field-based environmental observations to link cellular-level nitrogen cycling processes to large-scale geochemical patterns in both modern and ancient environments.

 

https://sites.lsa.umich.edu/jenanjk-lab/