Recent News...
Zehria floridana, a newly described genus and species of cyanobacteria. (Image credit: Mares et al., 2019)
Meet Zehria! A newly described genus of marine N2-fixing cyanobacteria is named in honor of Professor Zehr
April 2019
Jeffrey Johansen (John Carroll University) and colleagues disentangled the phylogeny of Cyanothece-like organisms and described two new genera of cyanobacteria, including Zehria, in a recent article in the Journal of Phycology.
Graduate student Katie Harding and colleagues demonstrate cyanobacterial N2 fixation in cold Arctic waters
December 2018
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Read a more integrative view and detailed description of the Zehr’s lab work aboard the Falkor here.
Eddy Exploration & Ecosystem Dynamics
Schmidt Ocean Institute
R/V Falkor
Ana Cabello and Rosie Gradoville, April-May 2018
The main objective of this cruise was to characterize the deep chlorophyll maximum within the center of eddy fields in the North Pacific Subtropical Gyre using long-range autonomous underwater vehicles (LRAUVs). These self-driving vehicles collect information about water temperature, chemistry, and chlorophyll and also are able to collect and preserve seawater samples at sea to study the microorganisms present. In parallel, our group was performing diel sampling every 3-6 hours from CTD casts, nitrogen fixation incubations on free drifting arrays, and deck-board experiments. These experiments all explored the diversity and activity of nitrogen-fixing bacteria, with special focus on UCYN-A. During the diel sampling we collected DNA, RNA and CARD-FISH samples at different depths to compare UCYN-A transcriptional activity and cell-division rates between surface and deep populations. Our incubation experiments investigated how UCYN-A cell-specific carbon and nitrogen fixation rates vary with depth (from 5 to 125m), and also tested whether UCYN-A is fixing nitrogen during the natural dark period.
 Zehrites |
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 SIO |
 SIO |
 CTD ops |
 CTD ops |
 Britt |
 Zehrites |
 Ana & Brittany |
 CTD crew |
 Ana |
 Matt |
 CTD sampling |
 CTD ops |
 pump deployment |
 Britt |
 Incubations |
 Incubation crew |
 R/V Gordon Sproul |
 R/V Gordon Sproul |
 Core cast crew |
 Incubations! |
 Incubations! |
 SIO |
 deck ops |
 deck ops |
 Catalina Island |
 deck ops |
 sunset |
What is UCYN-A doing in a coastal shelf ecosystem?
SP1729 R/V Gordon Sproul
Kendra Turk-Kubo, Ana Cabello, Britt Henke, Brittany Stewart, and honorary Zehr Lab member Jenna Spakeen (VIMS) in collaboration with Matt Mills and Arrigo Lab members (Stanford), October 2017
This was the second of two cruises scheduled this year off the coast of Baja. Our objectives for both cruises were to track growth rates, bulk and cell-specific N2 fixation, nitrate uptake rates, CO2 fixation, and metabolic activities of UCYN-A1 and UCYN-A2 in coastal waters. We also conducted core casts at each station to measure environmental variables including POC/PON, chl a, nutrients (N, P, Si) and take samples to characterize the microbial community composition (DNA/RNA/FCM/CARD-FISH).
 Baltic Room |
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 middle of the night in Nome |
 Nome Harbor |
 R/V Sikuliaq |
 R/V Sikuliaq |
 Leaving Nome |
 R/V Sikuliaq |
 The team |
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 dimming |
 CTD ops |
 CTD ops |
 Beaufort Sea |
 Beaufort Sea |
 Incubations |
 finally, night-ish |
 returning to land |
 Nome, from sea |
 charter from Barrow to Nome |
 BARC |
 Small boat ops |
 Small boat ops |
 thermokarst |
 sunset |
 BARC |
 R/V Ukpik |
 Sampling at the edge |
Are there Diazotrophs in the Arctic?
Field operations out of BARC &
R/V Sikuliaq
Kendra Turk-Kubo, Britt Henke, Katie Harding,
August-September 2017
This was our second trip to the Arctic to investigate the spatial extent of nitrogen fixation and which diazotroph species may be active in the Beaufort and Chukchi Sea (Arctic Ocean). Led by Rachel Sipler (VIMS), a team of researchers from VIMS, UCSC, and GIT have come together to study this enigma.
Follow the blog: https://thedynamicarctic.com
And hear an interview with K. Turk-Kubo about our research:
https://thedynamicarctic.com/2017/08/16/diazotrophs-in-the-arctic/
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 gradients cruise.com |
 CTD deployment |
 Sunset from the R/V Langseth |
Gradients 2.0 cruise in the North Pacific, from the Subtropical Gyre (21°N) to the Subarctic Gyre (43°N).
R/V Langseth
Rosie Gradoville and Brittany Stewart, May-June 2017
This cruise tracked the gradients in diversity and biogeochemistry in the North Pacific on a transect from the Subtropical Gyre to the Subarctic Gyre. We steamed north from Honolulu and mapped out the “transition zone” between the two gyres. Then, we turned around and sailed back to Hawaii, collecting samples at stations aimed at characterizing all three regions. The Zehr lab collected samples for DNA, RNA, and fluorescence in situ hybridization (FISH) in order to explore the diversity, abundance, and activity of nitrogen-fixing bacteria along this transect.
 The team |
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 R/V Gordon Sproul |
 R/V Gordon Sproul |
 IMG_9054 |
 Incubators |
 CTD control room |
 CTD control room |
 Core team! |
 Meredith operating the winch |
 Meredith operating the winch |
 Meredith operating the winch |
 Deployed! |
 Leona |
 CTD deployment |
 CTD deployment |
 The team! |
What is UCYN-A doing in a coastal shelf ecosystem?
SP1714 R/V Gordon Sproul
Kendra Turk-Kubo, Mary Hogan, Katie Harding, and honorary Zehr Lab members Meredith McPherson (UCSC) and Jenna Spakeen (VIMS) in collaboration with Matt Mills and Arrigo Lab members (Stanford), May 2017
Our objective on this cruise were to track growth rates, bulk and cell-specific N2 fixation, nitrate uptake rates, CO2 fixation, and metabolic activities of UCYN-A1 and UCYN-A2 in coastal waters. We also conducted core casts at each station to measure environmental variables including POC/PON, chl a, nutrients (N, P, Si) and take samples to characterize the microbial community composition (DNA/RNA/FCM/CARD-FISH).
While off the coast of Baja California, we encountered a storm - the seas were high and the boat was small. See the videos to the left!
In the News...
Gordon and Betty Moore Foundation awards Himadri Pakrasi (InCEES/WUStl) and Prof. Zehr funding to study the symbiotic relationship between oceanic cyanobacteria and microalgae
January 2017
Read the press release:
https://incees.wustl.edu/2017/01/26/1-million-grant-awarded-to-i-cares-director-and-ucsc-professor/
Link to the Pakrasi Lab:
https://sites.wustl.edu/photosynthbio/
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Prof. Zehr invited to give Plenary talk at The Third Xiamen Symposium on Marine Environmental Sciences
Xiamen, China, January 9-11, 2017
http://mel.xmu.edu.cn/conference/3XMAS/
Arctic Research Cruise, R/V Sikuliaq, September 3-29, 2016
Katie Harding, September 2016
We visited the Arctic to investigate the spatial extent of nitrogen fixation and which diazotroph species may be active in the Beaufort and Chukchi Sea (Arctic Ocean). Led by Rachel Sipler (VIMS), a team of researchers from VIMS, UCSC, and GIT have come together to study this enigma.
Follow the blog: https://thedynamicarctic.wordpress.com/
And read up on our research goals:
https://thedynamicarctic.wordpress.com/2016/08/31/an-arctic-fixation/
 The team |
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 Trace metal clean ziplock bags |
 Termite in bed |
 Sunset 2 |
 Pump watch view |
 Sunset |
 Krill |
 Leaving Honolulu |
 Incubation babies lined up |
 Incubators on a sunny day |
 Filtering for CARD-FISH in the dead box |
 Fitration setup |
 Filtering for Chl a |
 Calm seas |
 3000 m foam cups |
 Baby |
 CTD on deck |
Gradients cruise KOK1606, Transect northbound to 37°N along 158°W
Hanna Farnelid and Brittany Stewart, April-May 2016
Our objectives during the Gradients cruise were to characterize diazotroph diversity and abundances across the transition zone region between the North Pacific Subtropical Gyre and the Subpolar Gyre. Along the cruise tract, diazotroph diversity and community composition will be analyzed using nifH amplicon sequencing, quantitative PCR (qPCR) targeting known diazotrophs, and fluorescence in situ hybridization (FISH) targeting the unicellular symbiont UCYN-A. We also conducted mixing experiments between different water masses to simulate what happens in the transition zone. We had an eventful cruise with a termite swarm (!) and a toilet flooding but seas were mainly calm.
 women @ sea |
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 ready to deploy |
 in situ array recovery |
 in situ array recovery |
 in situ array bottles |
 safety @ sea |
 CTD recovery |
 CTD recovery |
 CTD recovery |
 CTD @ dusk |
 sunset |
 sunset |
 sunset |
 sunset |
 diamond head |
 returning to land |
 tug assist |
SCOPE cruise KM1605, North Pacific Subtropical Gyre
Mary Hogan and Kendra Turk-Kubo, March 2015
Our research group had several objectives for this cruise: 1) Investigate diazotroph growth rates under various nutrient, light, trace metal and temperature regimes; and 2) Investigate diazotroph grazing rates under different light and temperature regimes.
Prof. Zehr in the News:
'This is how scientists will save the Baltic Sea'
http://mobil.unt.se/uppland/uppsala/sa-ska-forskarna-radda-ostersjon-3848114.aspx
 R/V KOK (UH) |
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 Secured and ready for transit |
 Britt and the CTD rosette |
 Bird's eye view of the Niskins |
 Filtering station |
 Filtering! |
 Preparing for Array deployment |
 Incubation Array deployment |
 Incubation Array Recovery |
 Incubation Array Recovery |
 Incubation Array Recovery |
 Incubation Array recovery |
 Incubation Array Recovery |
 Deckboard incubations |
 Filtering in the air castle......is challenging! |
 Dead filtering zone |
 Dead filtering zone |
 Sunset in the NPSG |
 Sunset in the NPSG |
 Sunrise in the NPSG |
 Almost home! |
 Diamond Head |
SCOPE cruise KOK1507, 200 miles N. of Station ALOHA
Hanna Farnelid, Britt Henke and Kendra Turk-Kubo, July-August 2015
Our research group had several objectives for this cruise: 1) Investigate diazotroph growth rates under various nutrient, light and temperature regimes (K. Turk-Kubo); 2) Investigate particle associated and phytoplankton associated bacteria (H. Farnelid), and 3) Continue cultivation efforts to isolate the UCYN-A symbiont (B.Henke).
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C-MORE/SCOPE cruise C-20, Station ALOHA
Maria del Carmen Muñoz-Marin, April 2015
During the C-20 cruise, Postdoc Maria del Carmen Muñoz-Marin sampled diel cycles over 3 days for RNA, DNA and CARD-FISH. With these samples she will develop a whole genome array approach for the nitrogen-fixing cyanobacterium UCYN-A1. With this technique, she will try to determine the whole genome transcription patterns related to PSI, energy metabolism and nitrogenase gene expression over light-dark cycles.
Moreover, she will study the interaction between the host and the cyanobacterium during light-dark cycles using double CARD-FISH.
 R/V Ka`imikai-O-Kanaloa (UH)HOT cruises depart from Snug Harbor in Honolulu. The R/V Ka`imikai-O-Kanaloa (KOK) often transports the science team to Station ALOHA. |
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 Sunrise at Snug HarborA beautiful February morning in Honolulu. |
 Departing Snug HarborThe Honolulu Skyline as we depart Snug Harbor. |
 Last glimpses of landOceanographers have large collections of sky/sea shots like this! |
 UH Cytometry VanThis van houses a BD Influx cytometer, that our lab has used many times over the years. Many of our most exciting discoveries have been facilitated by this van. |
 Bridge of the KOKLooking towards the bridge of the KOK. |
 Growth rate incubationsThis is where we conduct microcosm incubations with the microbial community at Station ALOHA. This experiment was designed to measure growth and grazing rates of nitrogen fixing microbes. |
 IncubationsThese incubations were conducted in cubitainers, so that there was enough volume to sample for molecular work more than once. |
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HOT-269
Kendra Turk-Kubo and Hanna Farnelid, February 2015
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NEMO Cruise, August 2014
Irina Shilova, Julie Robidart, and colleagues from Stanford, MIT, and the Univeristy of Hawaii
In late summer of 2014, the UCSC, Stanford, and UH research team conducted a month long expedition named NEMO (Nutrient Effects on Marine microOrganisms), as a part of our research funded by the NSF Dimensions in Biodiversity program. The objective of the NEMO research cruise was to investigate the role of nitrogen in shaping phytoplankton biodiversity and physiology in the central North Pacific Ocean. Starting from San Diego, CA, they characterized the nutrient rich dynamic waters of the California Current System, followed by an extensive phytoplankton bloom in the middle of North Pacific Ocean, low-nutrient waters and a large Trichodesmium bloom near Hawaii. Through taking various physicochemical and biological measurements along the transect, and conducting nutrient manipulation experiments, they examined how different forms of nitrogenous substrates together with phosphorus and iron alter microbial community structure, physiology and the rates of phytoplankton photosynthesis.