February 24, 2024
Ph.D student Johnson Lin is the lead author on a study recently published in Limnology and Oceanography where we examined how diatoms respond to upwelling when under various iron states at narrow and wide shelf regions in the California Current System.
October 1, 2023
This NSF-funded project includes UNC PIs Adrian Marchetti and Harvey Seim, with collaborators Monique Messié at the Monterrey Bay Aquarium Research Institute (MBARI) and Diego Figueroa at University of Texas Rio Grande Valley (UT-RGV), who will use ship-based field sampling, a mooring, laboratory culture experiments and numerical modeling to examine how variations in nutrient delivery impact marine plankton in the Galápagos Archipelago.
September 28, 2023
Former undergraduate student Emily Pierce led a publication on comparing different methods for identification of diatoms in dynamic coastal communities. In this study, Emily compared 18s rRNA gene analysis with FlowCam imaging and light microscopy. Her findings show some consistencies, although cross-method comparisons should proceed with caution.
Comparison of advanced methodologies for diatom identification within dynamic coastal communities
September 18, 2023
Our study on proton-pumping rhodopsins (PPR) in Southern Ocean phytoplankton was just published in the Proceedings of the National Academy of Sciences. Led by former post-doc Sarah Andrew, we show that PPR in Southern Ocean diatoms is located in the vacuole, making it an alternative phototrophic organelle to the chloroplast. Energy produced by PPR increases under cold, low iron and high light conditions when photosynthetic rates are at their lowest. We found high expression of PPR genes and concentrations of retinal (the pigment used in PPR) in phytoplankton collected from environmental samples collected in waters surrounding the West Antarctic Peninsula.
Link to PNAS article here
Link to layperson summary on Kudos here
September 16, 2022
Our first paper contribution to the NASA EXPORTS program was recently published in Elementa: Science of the Anthropocene. In this study, Ph.D. candidate Meredith Meyer provides our findings on trends in new and regenerated production during the North Pacific EXPORTS field campaign. Meredith and coauthors show that the majority of net primary production (NPP) is performed by small cells growing on regenerated sources of nitrogen. Yet, any variations in NPP are primary driven by changes in nitrate-based new production.
May 18, 2022
Our second publication investigating the protistan communities in the Galápagos Archipelago was published recently in Frontiers in Marine Sciences. Former post-doc Se Hyeon jang led this effort to examine how environmental conditions influence marine protists with an emphasis on the micrograzer communities. We also report observation from a red tide bloom in Elizabeth Bay, Isabela Island. A bloom of the dinoflagellate Scripsiella lachrymosa was being actively grazed by another dinoflagellate, Polykrikos kofoidii.
Protistan communities within the Galápagos Archipelago with an emphasis on micrograzers
Dec. 19, 2021
Our new publication led by former graduate student Erika Neave was recently published in Environmental Microbiology. This publication is the first highlighting my groups research in the Galápagos Archipelago where we participated on annual research cruises that spanned the 2015/16 El Niño event. In this study, we found that the composition of the marine protist community was significantly influenced by deep water masses. This suggests that the ocean currents are a major source of plankton seed populations to the surface waters in the Galápagos and thus substantially influences plankton composition when these currents change as a result of El Niño-Southern Oscillation (ENSO) events.
Dec. 13, 2021
The video below was made by UNC undergraduate Heidi Hannoush, who was a student in my Marine Phytoplankton (MASC444) class last semester. She was inspired by all the phytoplankton groups she learned about and so made this video for an assignment in another class. Enjoy!
November 17, 2021
Congratulations to Johnson Lin who defended his M.Sc. thesis titled ‘Variability in the phytoplankton response to upwelling across the iron limitation mosaic within the California Current System’, Johnson performed nutrient uptake rates, flow cytometry and gene expression analysis to investigate how phytoplankton respond to simulated upwelling under varying iron physiological states. Turns out some diatoms are just more well-suited to coping with change than others.
April 10, 2021
In a recent study published in Nature Geosciences led by Chana Kranzler from the Thamatrakoln Lab at Rugers University, we examined how iron limitation in diatoms may affect viral infection. Molecular datasets used in the study were derived from incubation experiments led by members of the Marchetti lab during the IrnBru cruise in the California Upwelling Zone in 2014 and a Line P cruise in the Northeast Pacific in 2015. The study found an interesting ecological trade-off in how growth limitation by low iron availability may result in diatoms being less vulnerable to viral infection by slowing down mortality and reducing viral replication.
Impaired viral infection and reduced mortality of diatoms in iron-limited oceanic regions
A Nature Geosciences news and views article about the study is available here.
University Operator: (919) 962-2211 | © 2025 The University of North Carolina at Chapel Hill |