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Field Work

Oxygen Minimum Zones - Eastern Tropical North Pacific and Gulf of Mexico
2012-2015: As part of a multi-year project (Grant 1151698) funded by NSF's Biological Oceanography program, our lab works collaboratively with biogeochemists to explore how oxygen depletion affects the diversity, distribution, and function of marine bacterioplankton. Our primary field site is the large, permanent oxygen minimum zone in the Eastern Tropical North Pacific (ETNP) off northern Mexico. Dissolved oxygen concentrations in this region fall from near saturation at the surface to below detection (< 50 nM) within the OMZ depths (~150-750 m). This steep gradient is coupled with similarly sharp transitions in nutrients, light, and other energy substrates. Microorganisms associated with OMZ gradients mediate key biogeochemical cycles through diverse metabolic processes, including nitrification, denitrification, anaerobic ammonia oxidation (annamox), and sulfur oxidation. Our lab is particularly interested in understanding the diversity and activity of OMZ sulfur-utilizing bacteria across niches within OMZs (e.g., across depth zones, or between organic particle-associated or free-living microhabitats) and between OMZs with varying physical and geochemical conditions. To that end, we are also exploring microbial community diversity and function in regions with seasonal oxygen depletion and overall higher oxygen or nutrient concentrations, such as in the seasonally hypoxic (O2 < 20 uM) "deadzone" on the Louisiana Shelf. The following are from cruises to the ETNP OMZ (2013) and the Louisiana Shelf (2012).
corer reactor_GoM sampler
R/V Cape Hatteras (2012). Multicore deployment.
(Photo: H. Olins)
Bioreactors. Oxygen and sulfur experiments. In situ RNA sampler.
(Photo: H. Olins)
fishing 2013 OMZOMBIE ctd
Fishing, Louisiana Shelf. R/V New Horizon (2013). Oxygen Minimum Zone Microbial Biogeochemistry Expedition CTD deployment.
(Photo: H. Olins)

Oxygen Minimum Zone - Eastern Tropical South Pacific
2009-2010: As a post-doc (in Ed DeLong's lab at MIT) I used high-throughput sequencing to study the diversity and function of bacterioplankton from an oxygen minimum zone (OMZ) in the eastern South Pacific. Microorganisms associated with the OMZ mediate key biogeochemical cycles through a diverse range of metabolic processes, including nitrification, denitrification, anaerobic ammonia oxidation (annamox), and sulfur oxidation. As part of an international collaboration, the Chilean naval vessel R/V Vidal Gormaz was deployed to collect samples for characterizing the unique biogeochemistry of the OMZ. The following are from a cruise in August 2009, leaving out of the Chilean port of Iquique.
Fishing boats, Iquique. Filling bioreactors with OMZ water for shipboard experiments. Bioreactors. N, S, or O2 additions. MIT crew: me, Sara Lincoln, Julio Sepulveda (rear).
Leaving Iquique. Replica of the Peruvian ship Huascar. Cruise party. Bow of
Vidal Gormaz.
Whale. Species?
Albatross. Giant petrels. Sea lion. Whale again.

Warmer Climes
2003-2008: My Ph.D. thesis, completed in Colleen Cavanaug's lab at Harvard, examined the diversification of sulfur-oxidizing autotrophic bacteria living in symbiosis with marine invertebrates. Most of this work focused on symbionts of deep-sea clams (Family Vesicomyidae) living at hydrothermal vents and hydrocarbon cold seeps. A side-project, which morphed into the senior thesis of an undergrad in the lab (Alan Baik), examined the population genetics of the coastal bivalve Solemya velum, a shallow-water analog to deep-sea chemosynthetic symbioses. The following images are primarily from the Extreme 2003 cruise of the R/V Atlantis to the East Pacific Rise (chief scientist: Craig Cary).
Alvin going in
R/V Atlantis in Manzanillo, Mexico. Extreme 2003 cruise. (Photo: ILGN)
DSV Alvin.
Extreme 2003
9N East Pacific Rise (EPR).
On deck. FS, Andrea Nussbaumer, Colleen Cavanaugh, Irene Newton, Tara Harmer. (Photo: unknown)
Boarding Alvin.
(Photo: ILGN)
Alvin in water
Descending off the stern.
(Photo: ILGN)
Alvin at the surface.
(Photo: ILGN)
Post dive shower.
(Photo: ILGN)
Riftia pachyptila tubeworms in the biobox. (Photo: ILGN)
Riftia clump.
(Photo: ILGN)
Black smokers.
(Photo: ILGN)
Sampling Riftia.
(Photo: ILGN)
Bathymodiolus thermophilus mussels, EPR. (Photo: ILGN)
Sampling elevator launched from R/V Atlantis.
Extreme 2003 crew.
Sunset on the Pacific.
(Photo: ILGN)
Hanging with Eric DeChaine. Bow of the R/V Atlantis. Extreme 2004 cruise, EPR.




Solemya velum habitat, tidal mudflats, Point Judith, RI.
YouTube video of S. velum burrowing through glass beads. Courtesy of Guus Roeselers.
Solemya borealis, with foot extruded. Chemosynthetic symbionts live intracellularly
in the clam gills.
From Harvard's MCZ collection.
The smaller, and more ubiquitous, Solemya velum (left) with S. borealis. Sequencing of the S. velum symbiont genome should be completed in fall 2008.

Marguerite Bay, Western Antarctic Pennisula
2000-2002: My M.S. thesis, completed with Chris Fritsen at the Desert Research Institute, examined the extent to which algal and heterotrophic bacterial biomass are coupled across geographic and seasonal gradients in Antarctic sea ice. In collaboration with Alison Murray (DRI), a subset of this work used standard DGGE and 16S genotyping methods to quantify bacterial and archaeal diversity among sea ice sub-habitats (e.g., upper water column, ice brine, slush, ice core). We collected most of the samples for this work in the austral fall and winter during three research cruises (LMG-0106, NBP-0104, NBP-0204) to the Marguerite Bay region of the Western Antarctic Peninsula. This work was completed as part of the US Southern Ocean GLOBEC Program with funding from NSF's Office of Polar Programs.
Antarctic fur seal
R/V Nathaniel B. Palmer
docked in Punta Arenas, Chile.
Columbian ceremonial naval ship, Punta Arenas.
Antarctic fur seal,
Palmer Station.
Ice mushrooms,
near Adelaide Island.
NBP0104 cruise.
R/V Laurence M. Gould
Young sea ice, Laserev Bay.
Fritsen lab crew: Sarah Marschall and me. Palmer Station, LMG0104 cruise.
Near Adelaid Island.
Night coring.
NBP0104 cruise.

Adelie penguins on floe,
R/V LMG in background. NBP0104 cruise.

Mountains of the Antarctic Peninsula, near Palmer Station.
Rafted sea ice. Note algal layer at base of rafted floe.
night coring
silhouette from snowpit
Sunset over icebergs,
Laserev Bay.
Breaking trail for the Gould. NBP0104 cruise.

Coring sea ice,
NBP0104 cruise.

Sunrise from a snow pit. Coring sea ice in
Marguerite Bay.
ship in ice
Ice floes, Marguerite Bay. (Photo: G. Lawson)

Western Antarctic Peninsula.
(Photo: unknown)

(Photo: G. Lawson)
R/V LMG seen from stern of the Palmer, Marguerite Bay. (Photo: G. Lawson)
Below: DAPI-stained cells (blue under UV) isolated from Antarctic sea ice.
These ice samples were collected by CHF in the Ross Sea (NBP-9901 cruise)

McMurdo Dry Valleys, Antarctica
Dec. 1999-Feb. 2000: During my senior year at Middlebury, I assisted Chris Fritsen and Ed Adams (Montana State) in sampling the microbial life locked within glaciers and lake ice of Antarctica's McMurdo Dry Valleys (see the Dry Valley LTER site). This project, funded by NSF's Life in Extreme Environments (LExEn) program, focused on the amazing capacity for microorganisms to persist in the harshest environments on Earth. This work formed the basis for a senior thesis examining the spatial distriibution and abundance of phototrophs (mostly cyanobacteria) in perrenial ice covers of Lakes Fryxell and Bonney.

Mount Erebus,
from McMurdo Station.

1:00 am, Jan. 1, 2000. Happy New Millenium.
On the Ross Ice shelf.
Castle Rock and Mount Erebus, from McMurdo.
Fryxell base
Sampling on L. Fryxell
sampling on L. Bonney
Lake Fryxell base,
sleeping tents behind.
Julie Hunter (grad student, left), Chris (center), Ed.
Hard at work on Lake Fryxell. Julie (left), Chris (rear).
West lobe of Lake Bonney, Taylor Glacier behind.
Canada Glacier
On Taylor Glacier
Helo on glacier
On the Canada Glacier.
Weddell seal near
Discovery Bluff.
On the Taylor Glacier,
upper Taylor Valley.
Landing on the
Canada Glacier.
Ventifact, midnight,
above Lake Bonney.
Taylor Valley.
Sledding gear across
Lake Fryxell.
Ross Sea fauna.
Below: DAPI-stained cells (blue under UV) isolated from the ice and water column of Lakes Fryxell and Bonney.
ice water
water column ~6-10m beneath lake ice

Bering Sea
Summer 1998: My first exposure to field and laboratory research was as an undergrad at Middlebury College. Under the guidance of Matthew Dick (Middlebury) and Eric Munk (Alaska Fisheries Science Center, NMFS), I studied the systematics of marine encusting bryozoans. We collected specimens during a NMFS trawl survey in the Bering Sea and using scanning electron microscopy to make taxonomic identifications based on zooid and colony morphology. This work was funded by an HHMI summer internship grant.
F/V Aldebaran, sister ship to F/V Arcturas during the NMFS trawl survey.
Sorting table on the back deck of the F/V Arcturas.
Home port: Dutch Harbor, Alaska.
Bryozoans show amazing diversity in skeletal/colony structure (above and below).