Trends in new production during NP NASA EXPORTS

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.

Phytoplankton size-class contributions to new and regenerated production during the EXPORTS Northeast Pacific Ocean field deployment

New publication in Frontiers in Marine Science!

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

New publication in Environmental Microbiology!

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.

Protistan plankton communities in the Galápagos Archipelago respond to changes in deep water masses resulting from the 2015/16 El Niño

Phytoplankton: Thinking in microns

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!


Johnson defends his M.Sc. thesis!

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.

Iron limitation in diatoms impairs viral infection

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.

New publication in mSystems!

March 30, 2021

Chaetoceros decipiens

Our new publication led by former Master’s student Rob Lampe was recently published in mSystems.  In this study we simulated the upwelling conveyor belt cycle (UCBC) to examine how a common diatom and coccolithophore originally isolated from the California upwelling zone respond to changes associated with the cycle.  In addition, we examined the effects of iron-limitation on how these two phytoplankton species cope with the UCBC.  Our findings show that the diatom Chaetoceros decipiens is particularly well-adapted to upwelling cycles.  Co-authors include current graduate student Johnson Lin and former undergraduate researcher Gustavo Hernandez.


Representative Diatom and Coccolithophore Species Exhibit Divergent Responses throughout Simulated Upwelling Cycles

Carly defends her Ph.D. thesis!

Oct. 29, 2020

Congratulations to Dr. Carly Moreno who successfully defended her Ph.D. thesis titled ‘Coupled molecular physiology and ecology of Southern Ocean diatoms in response to shifting iron and light availability’. Carly’s research investigated how polar diatoms acclimate and adapt to varying iron concentrations and light levels, providing new insights into how phytoplankton communities may shift in rapidly changing polar environments.  The punchline is that not all diatoms are created equal!


New publication in Environmental Microbiology!

September 19, 2020

Our new publication led by former Ph.D. student Weida Gong was recently published in Environmental Microbiology.  In this study why compare and contrast multiple approaches for taxonomic identification of eukaryotic phytoplankton in the Neuse River Estuary and examine the environmental factors that influence phytoplankton composition.  Our findings provide additional support and validation for the integration of environmental genomics into coastal water quality monitoring programs.

Phytoplankton composition in a eutrophic estuary: Comparison of multiple taxonomic approaches and influence of environmental factors

New publication in Limnology and Oceanography!

February  7, 2020

Our new publication led by Ph.D. candidate Carly Moreno was recently published in the journal Limnology and Oceanography.  In this study we examine the interactive response of the Southern Ocean diatom Fragilariopsis kerguelensis to changes in light and iron.  The transcriptome analysis reveals mechanisms that may underpin the ecological success of this diatom in low iron and light environments, highlighting the important role of diversified photosynthetic isoforms, iron acquisition, unique detoxification mechanisms of reactive oxygen species, and metabolic shifts in amino acid recycling and carbon metabolism.

Interactive effects of iron and light limitation on the molecular physiology of the Southern Ocean diatom Fragilariopsis kerguelensis