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Dr. Close instructs undergraduate student Nicola Paul on operation of the GC-IRMS
Lipid extracts from a depth profile at Station ALOHA
Dr. Close deploying in situ pumps in the North Pacific
Dr. Close and Ph.D. student Shannon Doherty deploying in situ pumps in Monterey Bay
Lipid extracts from the Eastern Tropical North Pacific
R/V Knorr docked in Barbados on one of its last voyages in 2013 (Deep DOM cruise)
Sunset over the Eastern Tropical North Pacific
Installation of the magnet on the MAT 253 isotope ratio mass spectrometer
Group Photo, 2019-2020 Group Photo, 2019-2020
Close Lab group, 2019-2020
Close Lab group, 2017-2018

Marine Organic and Isotope Geochemistry

The Close Lab specializes in particle sampling, purification of organic compound classes, and compound-specific isotope analysis in order to constrain how organic matter is produced, degraded, and physically distributed in marine environments. The lab includes equipment for the extraction and purification of lipids, amino acids, and other compound classes and instrumentation for compound identification (GC-MS), bulk stable isotope analysis (EA-IRMS), and compound-specific isotope analysis of lipids and amino acids (GC-IRMS). Research opportunities for undergraduate students are always available.

News and updates


June 2021: Shannon Doherty successfully defended her Ph.D. on June 14th -- congratulations Dr. Doherty!

Four students in the Close Lab will present research at the ASLO Aquatic Sciences virtual meeting. On June 24, look for a talk by Lillian Henderson on her recent work identifying photosynthetic carbon isotope signatures of the lower euphotic zone and a poster by Paul Wojtal on his work interpreting mechanisms of carbon flux attenuation in the northeast Pacific. On June 25, Shannon Doherty will give a talk on recent work using nitrogen isotopes of amino acids to estimate fecal pellet composition of particles in Monterey Bay, and Suzanne Stremler will present a poster demonstrating that the periostracum of deep-sea mussels retains unique compound-specific isotope signatures related to methanotrophy.


May 2021: New open-access paper out now! Led by fifth-year Ph.D. candidate Shannon Doherty: Distinguishing zooplankton fecal pellets as a component of the biological pump using compound-specific isotope analysis of amino acids


Congratulations to Suzanne Stremler for a great senior honors thesis, "Compound-specific isotope analysis of periostracum growth bands from Bathymodiolus childressi: potential temporal archive of ecology at methane seeps". We wish Suzanne the best of luck as a Ph.D. student at UC Santa Cruz starting in the fall!


September 2020: New open-access paper out now! By Dr. Close and Ph.D. student Lillian Henderson: Open-ocean minima in δ13C values of particulate organic carbon in the lower euphotic zone, Frontiers in Marine Science.


August 2020: The Close Lab bids a fond farewell to research assistant Joshua Pi, who kept isotope analyses going throughout much of the pandemic. Josh is off to a Ph.D. program at the Graduate School of Oceanography at the University of Rhode Island, studying with Dr. Kelton McMahon.


Summer 2020: This summer has been turbulent for many reasons. Lab members have continued to check in with each other frequently over video chats, have practiced safe interactions in the lab, and have been active in anti-racism efforts. Please visit the webpage of the RSMAS Diversity, Equity and Inclusion Committee as one starting place for information about equipping ourselves to take active roles in building more inclusive and diverse STEM environments and for university plans for advancing racial justice.


March 2020: Dr. Close visited UC Santa Barbara to give the last in-person seminar for the Interdepartmental Graduate Program in Marine Science before all travel was shut down due to SARS-CoV-2. Many thanks to members of the Carlson Lab (and many others) for their hospitality!


February 2020: Shannon and Hilary were back in California for the 2020 Ocean Sciences Meeting. See the abstracts here (Doherty et al.) and here (Close et al.). Some new work from our collaborative projects was also featured: Romero-Romero et al. and Shea et al. from the Popp Lab (Hawaii), relating to dietary usage of small particles by zooplankton, and Vookhshoori et al. from the McCarthy Lab (UCSC), relating to the N isotopic signatures of chemosymbiosis at seafloor methane seeps.


December 2019: Shannon and Dr. Close presented exciting new isotope data at the AGU Fall Meeting in San Francisco. See the abstracts here (Doherty et al., compound-specific isotope analysis of fecal pellets) and here (Close, new interpretation of water column organic carbon isotope ratios)


August 2019: We are excited to welcome two new Ph.D. students to the lab! Look out for great things from Lillian Henderson and Paul Wojtal.

Dr. Close presented at the 2019 Goldschmidt meeting in Barcelona. See the abstract here.

July 2019: Dr. Close participated in her second summer research cruise with the BIOS-SCOPE collaboration, sampling large-volume, size-fractionated particles from the oligotrophic North Atlantic. Collaborators investigating microbial and metabolomic properties of these particle samples include Dr. Craig Carlson (UCSB) and Dr. Liz Kujawinski (WHOI).

June 2019: This month we welcome summer undergraduate researcher Sophia Schiaroli from Franklin and Marshall College. She is joining MGS Ph.D. student Evan Moore in extracting organic biomarkers from shallow-water carbonate rocks. At the same time, we bid a fond farewell to research assistant Nicola Paul, who has been the master of many lab techniques in her two years with our group. We wish her great success in her new position as Ph.D. student in the Santoro Lab at UCSB.

May 2019: Shannon joined a research cruise to the BATS (oligotrophic North Atlantic) site with our EXPORTS collaborator Dr. Amy Maas (BIOS) to collect particles, zooplankton, and fecal pellets.

April 2019: Via our partnership with the U.S. Geological Survey, we are excited to obtain samples from the water column and seafloor around a deep-sea coral habitat on the U.S. mid-Atlantic margin. See more about the multi-agency research happening this April on board the Ronald H. Brown here.

February 2019: Dr. Close presented at the ASLO meeting in San Juan, Puerto Rico on our work with the U.S. Geological Survey at methane seeps in the mid-Atlantic.

September 2018: The Close Lab has joined the EXPORTS team! We are grateful to our collaborators for collecting samples in the subarctic Pacific, onboard the R/V Roger Revelle and R/V Sally Ride in August-September, 2018. See our NSF project description here.

August 2018:

Shannon collected particle samples along a transect in the North Pacific onboard the R/V Oceanus in August, 2018, alongside other RSMAS researchers and alumni.

Dr. Close presented at Goldschmidt 2018 in Boston. See the abstract here.