Lloyd Karen G.

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Lloyd

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Karen G.

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0000-0003-0914-6375

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Drill site locations from MPSV GREATSHIP MANISHA IODP-347 cruise in the Baltic Sea in 2013 (IODP-347 Microbial Quantification project)

(Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2016-11-15) Lloyd, Karen G. ; Steen, Andrew D.

In 2013, Integrated Ocean Drilling Program Expedition 347 sampled six subbasins within the Baltic Sea Basin in an effort to understand the sedimentological record of climate dynamics over the last 140,000 years. These sites, including Bornholm Basin (BSB-7), Lille Belt (BSB-3), and Anholt Loch (BSB-9), were selected because they contain varved, rapidly deposited sediments that represent an archive of paleoclimatological information spanning from the last glacial cycle. This expedition was led by Dr. Bo Barker Jørgensen of Aarhus University and Dr. Thomas Andrén of Södertörn University aboard the vessel MPSV GREATSHIP MANISHA. Data included here are dates sampled, latitude and longitude, and depth of overlying water. For a complete list of measurements, refer to the supplemental document 'Field_names.pdf', and a full dataset description is included in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: http://www.bco-dmo.org/dataset/641342
Sulfide ameliorates metal toxicity for deep-sea hydrothermal vent archaea

(American Society for Microbiology, 2004-04) Edgcomb, Virginia P. ; Molyneaux, Stephen J. ; Saito, Mak A. ; Lloyd, Karen G. ; Boer, Simone ; Wirsen, Carl O. ; Atkins, Michael S. ; Teske, Andreas

The chemical stress factors for microbial life at deep-sea hydrothermal vents include high concentrations of heavy metals and sulfide. Three hyperthermophilic vent archaea, the sulfur-reducing heterotrophs Thermococcus fumicolans and Pyrococcus strain GB-D and the chemolithoautotrophic methanogen Methanocaldococcus jannaschii, were tested for survival tolerance to heavy metals (Zn, Co, and Cu) and sulfide. The sulfide addition consistently ameliorated the high toxicity of free metal cations by the formation of dissolved metal-sulfide complexes as well as solid precipitates. Thus, chemical speciation of heavy metals with sulfide allows hydrothermal vent archaea to tolerate otherwise toxic metal concentrations in their natural environment.
Effects of dissolved sulfide, pH, and temperature on growth and survival of marine hyperthermophilic archaea

(American Society for Microbiology, 2005-10) Lloyd, Karen G. ; Edgcomb, Virginia P. ; Molyneaux, Stephen J. ; Boer, Simone ; Wirsen, Carl O. ; Atkins, Michael S. ; Teske, Andreas

The ability of metabolically diverse hyperthermophilic archaea to withstand high temperatures, low pHs, high sulfide concentrations, and the absence of carbon and energy sources was investigated. Close relatives of our study organisms, Methanocaldococcus jannaschii, Archaeoglobus profundus, Thermococcus fumicolans, and Pyrococcus sp. strain GB-D, are commonly found in hydrothermal vent chimney walls and hot sediments and possibly deeper in the subsurface, where highly dynamic hydrothermal flow patterns and steep chemical and temperature gradients provide an ever-changing mosaic of microhabitats. These organisms (with the possible exception of Pyrococcus strain GB-D) tolerated greater extremes of low pH, high sulfide concentration, and high temperature when actively growing and metabolizing than when starved of carbon sources and electron donors/acceptors. Therefore these organisms must be actively metabolizing in the hydrothermal vent chimneys, sediments, and subsurface in order to withstand at least 24 h of exposure to extremes of pH, sulfide, and temperature that occur in these environments.
Heterotrophic Archaea dominate sedimentary subsurface ecosystems off Peru

(National Academy of Sciences, 2006-02-27) Biddle, Jennifer F. ; Lipp, Julius S. ; Lever, Mark A. ; Lloyd, Karen G. ; Sorensen, Ketil B. ; Anderson, Rika E. ; Fredricks, Helen F. ; Elvert, Marcus ; Kelly, Timothy J. ; Schrag, Daniel P. ; Sogin, Mitchell L. ; Brenchley, Jean E. ; Teske, Andreas ; House, Christopher H. ; Hinrichs, Kai-Uwe

Studies of deeply buried, sedimentary microbial communities and associated biogeochemical processes during Ocean Drilling Program Leg 201 showed elevated prokaryotic cell numbers in sediment layers where methane is consumed anaerobically at the expense of sulfate. Here, we show that extractable archaeal rRNA, selecting only for active community members in these ecosystems, is dominated by sequences of uncultivated Archaea affiliated with the Marine Benthic Group B and the Miscellaneous Crenarchaeotal Group, whereas known methanotrophic Archaea are not detectable. Carbon flow reconstructions based on stable isotopic compositions of whole archaeal cells, intact archaeal membrane lipids, and other sedimentary carbon pools indicate that these Archaea assimilate sedimentary organic compounds other than methane even though methanotrophy accounts for a major fraction of carbon cycled in these ecosystems. Oxidation of methane by members of Marine Benthic Group B and the Miscellaneous Crenarchaeotal Group without assimilation of methane–carbon provides a plausible explanation. Maintenance energies of these subsurface communities appear to be orders of magnitude lower than minimum values known from laboratory observations, and ecosystem-level carbon budgets suggest that community turnover times are on the order of 100–2,000 years. Our study provides clues about the metabolic functionality of two cosmopolitan groups of uncultured Archaea.
The Guaymas Basin hiking guide to hydrothermal mounds, chimneys, and microbial mats : complex seafloor expressions of subsurface hydrothermal circulation

(Frontiers Media, 2016-02-18) Teske, Andreas ; de Beer, Dirk ; McKay, Luke J. ; Tivey, Margaret K. ; Biddle, Jennifer F. ; Hoer, Daniel ; Lloyd, Karen G. ; Lever, Mark A. ; Røy, Hans ; Albert, Daniel B. ; Mendlovitz, Howard P. ; MacGregor, Barbara J.

The hydrothermal mats, mounds, and chimneys of the southern Guaymas Basin are the surface expression of complex subsurface hydrothermal circulation patterns. In this overview, we document the most frequently visited features of this hydrothermal area with photographs, temperature measurements, and selected geochemical data; many of these distinct habitats await characterization of their microbial communities and activities. Microprofiler deployments on microbial mats and hydrothermal sediments show their steep geochemical and thermal gradients at millimeter-scale vertical resolution. Mapping these hydrothermal features and sampling locations within the southern Guaymas Basin suggest linkages to underlying shallow sills and heat flow gradients. Recognizing the inherent spatial limitations of much current Guaymas Basin sampling calls for comprehensive surveys of the wider spreading region.
United States contributions to the Second International Indian Ocean Expedition (US IIOE-2)

(US Steering Committee, 2018-10-23) Hood, Raleigh R. ; Beal, Lisa M. ; Benway, Heather M. ; Chandler, Cynthia L. ; Coles, Victoria J. ; Cutter, Gregory A. ; Dick, Henry J. B. ; Gangopadhyay, Avijit ; Goes, Joachim I. ; Humphris, Susan E. ; Landry, Michael R. ; Lloyd, Karen G. ; McPhaden, Michael J. ; Murtugudde, Raghu ; Subrahmanyam, Bulusu ; Susanto, R. Dwi ; Talley, Lynne D. ; Wiggert, Jerry D. ; Zhang, Chidong

From the Preface: The purpose of this document is to motivate and coordinate U.S. participation in the Second International Indian Ocean Expedition (IIOE-2) by outlining a core set of research priorities that will accelerate our understanding of geologic, oceanic, and atmospheric processes and their interactions in the Indian Ocean. These research priorities have been developed by the U.S. IIOE-2 Steering Committee based on the outcomes of an interdisciplinary Indian Ocean science workshop held at the Scripps Institution of Oceanography on September 11-13, 2017. The workshop was attended by 70 scientists with expertise spanning climate, atmospheric sciences, and multiple sub-disciplines of oceanography. Workshop participants were largely drawn from U.S. academic institutions and government agencies, with a few experts invited from India, China, and France to provide a broader perspective on international programs and activities and opportunities for collaboration. These research priorities also build upon the previously developed International IIOE-2 Science Plan and Implementation Strategy. Outcomes from the workshop are condensed into five scientific themes: Upwelling, inter-ocean exchanges, monsoon dynamics, inter-basin contrasts, marine geology and the deep ocean. Each theme is identified with priority questions that the U.S. research community would like to address and the measurements that need to be made in the Indian Ocean to address them.
High (3)He/(4)He in central Panama reveals a distal connection to the Galápagos plume

(National Academy of Sciences, 2021-11-23) Bekaert, David V. ; Gazel, Esteban ; Turner, Stephen ; Behn, Mark D. ; de Moor, J. Maarten ; Zahirovic, Sabin ; Manea, Vlad C. ; Hoernle, Kaj A. ; Fischer, Tobias P. ; Hammerstrom, Alexander ; Seltzer, Alan M. ; Kulongoski, Justin T. ; Patel, Bina S. ; Schrenk, Matthew O. ; Halldórsson, Saemundur ; Nakagawa, Mayuko ; Ramírez, Carlos J. ; Krantz, John A. ; Yucel, Mustafa ; Ballentine, Christopher J. ; Giovannelli, Donato ; Lloyd, Karen G. ; Barry, Peter H.

It is well established that mantle plumes are the main conduits for upwelling geochemically enriched material from Earth's deep interior. The fashion and extent to which lateral flow processes at shallow depths may disperse enriched mantle material far (>1,000 km) from vertical plume conduits, however, remain poorly constrained. Here, we report He and C isotope data from 65 hydrothermal fluids from the southern Central America Margin (CAM) which reveal strikingly high 3He/4He (up to 8.9RA) in low-temperature (≤50 °C) geothermal springs of central Panama that are not associated with active volcanism. Following radiogenic correction, these data imply a mantle source 3He/4He >10.3RA (and potentially up to 26RA, similar to Galápagos hotspot lavas) markedly greater than the upper mantle range (8 ± 1RA). Lava geochemistry (Pb isotopes, Nb/U, and Ce/Pb) and geophysical constraints show that high 3He/4He values in central Panama are likely derived from the infiltration of a Galápagos plume–like mantle through a slab window that opened ∼8 Mya. Two potential transport mechanisms can explain the connection between the Galápagos plume and the slab window: 1) sublithospheric transport of Galápagos plume material channeled by lithosphere thinning along the Panama Fracture Zone or 2) active upwelling of Galápagos plume material blown by a “mantle wind” toward the CAM. We present a model of global mantle flow that supports the second mechanism, whereby most of the eastward transport of Galápagos plume material occurs in the shallow asthenosphere. These findings underscore the potential for lateral mantle flow to transport mantle geochemical heterogeneities thousands of kilometers away from plume conduits.
The helium and carbon isotope characteristics of the Andean Convergent Margin

(Frontiers Media, 2022-06-13) Barry, Peter H. ; de Moor, J. Maarten ; Chiodi, Agostina ; Aguilera, Felipe ; Hudak, Michael R. ; Bekaert, David V. ; Turner, Stephen ; Curtice, Joshua ; Seltzer, Alan M. ; Jessen, Gerdhard L. ; Osses, Esteban ; Blamey, Jenny M. ; Amenabar, Maximiliano J. ; Selci, Matteo ; Cascone, Martina ; Bastianoni, Alessia ; Nakagawa, Mayuko ; Filipovich, Rubén ; Bustos, Emilce ; Schrenk, Matthew O. ; Buongiorno, Joy ; Ramirez, Carlos J. ; Rogers, Timothy J. ; Lloyd, Karen G. ; Giovannelli, Donato

Subduction zones represent the interface between Earth’s interior (crust and mantle) and exterior (atmosphere and oceans), where carbon and other volatile elements are actively cycled between Earth reservoirs by plate tectonics. Helium is a sensitive tracer of volatile sources and can be used to deconvolute mantle and crustal sources in arcs; however it is not thought to be recycled into the mantle by subduction processes. In contrast, carbon is readily recycled, mostly in the form of carbon-rich sediments, and can thus be used to understand volatile delivery via subduction. Further, carbon is chemically-reactive and isotope fractionation can be used to determine the main processes controlling volatile movements within arc systems. Here, we report helium isotope and abundance data for 42 deeply-sourced fluid and gas samples from the Central Volcanic Zone (CVZ) and Southern Volcanic Zone (SVZ) of the Andean Convergent Margin (ACM). Data are used to assess the influence of subduction parameters (e.g., crustal thickness, subduction inputs, and convergence rate) on the composition of volatiles in surface volcanic fluid and gas emissions. He isotopes from the CVZ backarc range from 0.1 to 2.6 RA (n = 23), with the highest values in the Puna and the lowest in the Sub-Andean foreland fold-and-thrust belt. Atmosphere-corrected He isotopes from the SVZ range from 0.7 to 5.0 RA (n = 19). Taken together, these data reveal a clear southeastward increase in 3He/4He, with the highest values (in the SVZ) falling below the nominal range associated with pure upper mantle helium (8 ± 1 RA), approaching the mean He isotope value for arc gases of (5.4 ± 1.9 RA). Notably, the lowest values are found in the CVZ, suggesting more significant crustal inputs (i.e., assimilation of 4He) to the helium budget. The crustal thickness in the CVZ (up to 70 km) is significantly larger than in the SVZ, where it is just ∼40 km. We suggest that crustal thickness exerts a primary control on the extent of fluid-crust interaction, as helium and other volatiles rise through the upper plate in the ACM. We also report carbon isotopes from (n = 11) sites in the CVZ, where δ13C varies between −15.3‰ and −1.2‰ [vs. Vienna Pee Dee Belemnite (VPDB)] and CO2/3He values that vary by over two orders of magnitude (6.9 × 108–1.7 × 1011). In the SVZ, carbon isotope ratios are also reported from (n = 13) sites and vary between −17.2‰ and −4.1‰. CO2/3He values vary by over four orders of magnitude (4.7 × 107–1.7 × 1012). Low δ13C and CO2/3He values are consistent with CO2 removal (e.g., calcite precipitation and gas dissolution) in shallow hydrothermal systems. Carbon isotope fractionation modeling suggests that calcite precipitation occurs at temperatures coincident with the upper temperature limit for life (122°C), suggesting that biology may play a role in C-He systematics of arc-related volcanic fluid and gas emissions.
Sampling across large-scale geological gradients to study geosphere–biosphere interactions

(Frontiers Media, 2022-10-31) Giovannelli, Donato ; Barry, Peter H. ; de Moor, J. Maarten ; Jessen, Gerdhard L. ; Schrenk, Matthew O. ; Lloyd, Karen G.

Despite being one of the largest microbial ecosystems on Earth, many basic open questions remain about how life exists and thrives in the deep subsurface biosphere. Much of this ambiguity is due to the fact that it is exceedingly difficult and often prohibitively expensive to directly sample the deep subsurface, requiring elaborate drilling programs or access to deep mines. We propose a sampling approach which involves collection of a large suite of geological, geochemical, and biological data from numerous deeply-sourced seeps—including lower temperature sites—over large spatial scales. This enables research into interactions between the geosphere and the biosphere, expanding the classical local approach to regional or even planetary scales. Understanding the interplay between geology, geochemistry and biology on such scales is essential for building subsurface ecosystem models and extrapolating the ecological and biogeochemical roles of subsurface microbes beyond single site interpretations. This approach has been used successfully across the Central and South American Convergent Margins, and can be applied more broadly to other types of geological regions (i.e., rifting, intraplate volcanic, and hydrothermal settings). Working across geological spatial scales inherently encompasses broad temporal scales (e.g., millions of years of volatile cycling across a convergent margin), providing access to a framework for interpreting evolution and ecosystem functions through deep time and space. We propose that tectonic interactions are fundamental to maintaining planetary habitability through feedbacks that stabilize the ecosphere, and deep biosphere studies are fundamental to understanding geo-bio feedbacks on these processes on a global scale.
Quantitative PCR data from sediment samples from MPSV GREATSHIP MANISHA IODP-347 cruise in the Baltic Sea in 2013 (IODP-347 Microbial Quantification project)

(Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2016-11-15) Lloyd, Karen G. ; Steen, Andrew D.

These data include the quantification of specific microbial taxa within the sediments collected during Integrated Ocean Drilling Program (IODP) Expedition 347: Baltic Sea. DNA was extracted from the interior of frozen whole round cores sampled from Little Belt, Anholt Loch, Landsort Deep, and Bornholm Basin at The University of Tennessee. For a more detailed description of drill sites, access the data set, "IODP-347 drill site locations". Primers specifically targeting the 16S rRNA gene of bacteria, archaea, anaerobic methane oxidizers (ANME-1), and Miscellaneous Crenarchaeota Group (MCG; taxonomically reassigned as the Bathyarchaeota phylum of Archaea) were used to assess abundance of these microbial groups. Abundance data was generated using quantitative-PCR (qPCR) and a non-specific, intercalating DNA stain, SYBR Green. Values were compared against a standard curve to generate copies/uL. These data were collected by Alex Shumaker as part of Dr. Karen Lloyd and Dr. Andrew Steen’s project funded by the National Science Foundation entitled, "Quantifying the contribution of the deep biosphere in the marine sediment carbon cycle using deep-sea sediment cores from the Baltic Sea". For a complete list of measurements, refer to the supplemental document 'Field_names.pdf', and a full dataset description is included in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: http://www.bco-dmo.org/dataset/641358
Ultrahigh-precision noble gas isotope analyses reveal pervasive subsurface fractionation in hydrothermal systems

(American Association for the Advancement of Science, 2023-03-16) Bekaert, David V. ; Barry, Peter H. ; Broadley, Michael W. ; Byrne, David J. ; Marty, Bernard ; Ramírez, Carlos J. ; de Moor, J Maarten ; Rodriguez, Alejandro ; Hudak, Michael R. ; Subhas, Adam V. ; Halldórsson, Saemundur A. ; Stefánsson, Andri ; Caracausi, Antonio ; Lloyd, Karen G. ; Giovannelli, Donato ; Seltzer, Alan M.

Mantle-derived noble gases in volcanic gases are powerful tracers of terrestrial volatile evolution, as they contain mixtures of both primordial (from Earth's accretion) and secondary (e.g., radiogenic) isotope signals that characterize the composition of deep Earth. However, volcanic gases emitted through subaerial hydrothermal systems also contain contributions from shallow reservoirs (groundwater, crust, atmosphere). Deconvolving deep and shallow source signals is critical for robust interpretations of mantle-derived signals. Here, we use a novel dynamic mass spectrometry technique to measure argon, krypton, and xenon isotopes in volcanic gas with ultrahigh precision. Data from Iceland, Germany, United States (Yellowstone, Salton Sea), Costa Rica, and Chile show that subsurface isotope fractionation within hydrothermal systems is a globally pervasive and previously unrecognized process causing substantial nonradiogenic Ar-Kr-Xe isotope variations. Quantitatively accounting for this process is vital for accurately interpreting mantle-derived volatile (e.g., noble gas and nitrogen) signals, with profound implications for our understanding of terrestrial volatile evolution.
Helium, inorganic and organic carbon isotopes of fluids and gases across the Costa Rica convergent margin

(Nature Research, 2019-11-25) Barry, Peter H. ; Nakagawa, Mayuko ; Giovannelli, Donato ; de Moor, J. Maarten ; Schrenk, Matthew O. ; Seltzer, Alan M. ; Manini, Elena ; Fattorini, Daniele ; di Carlo, Marta ; Regoli, Francesco ; Fullerton, Katherine ; Lloyd, Karen G.

In 2017, fluid and gas samples were collected across the Costa Rican Arc. He and Ne isotopes, C isotopes as well as total organic and inorganic carbon concentrations were measured. The samples (n = 24) from 2017 are accompanied by (n = 17) samples collected in 2008, 2010 and 2012. He-isotopes ranged from arc-like (6.8 RA) to crustal (0.5 RA). Measured dissolved inorganic carbon (DIC) δ13CVPDB values varied from 3.55 to −21.57‰, with dissolved organic carbon (DOC) following the trends of DIC. Gas phase CO2 only occurs within ~20 km of the arc; δ13CVPDB values varied from −0.84 to −5.23‰. Onsite, pH, conductivity, temperature and dissolved oxygen (DO) were measured; pH ranged from 0.9–10.0, conductivity from 200–91,900 μS/cm, temperatures from 23–89 °C and DO from 2–84%. Data were used to develop a model which suggests that ~91 ± 4.0% of carbon released from the slab/mantle beneath the Costa Rican forearc is sequestered within the crust by calcite deposition with an additional 3.3 ± 1.3% incorporated into autotrophic biomass.
Complex organic matter degradation by secondary consumers in chemolithoautotrophy-based subsurface geothermal ecosystems

(Public Library of Science, 2023-08-18) Paul, Raegan ; Rogers, Timothy J. ; Fullerton, Kate M. ; Selci, Matteo ; Cascone, Martina ; Stokes, Murray H. ; Steen, Andrew D. ; de Moor, J. Maarten ; Chiodi, Agostina ; Stefansson, Andri ; Halldorsson, Saemundur ; Ramirez, Carlos J. ; Jessen, Gerdhard L. ; Barry, Peter H. ; Cordone, Angelina ; Giovannelli, Donato ; Lloyd, Karen G.

Microbial communities in terrestrial geothermal systems often contain chemolithoautotrophs with well-characterized distributions and metabolic capabilities. However, the extent to which organic matter produced by these chemolithoautotrophs supports heterotrophs remains largely unknown. Here we compared the abundance and activity of peptidases and carbohydrate active enzymes (CAZymes) that are predicted to be extracellular identified in metagenomic assemblies from 63 springs in the Central American and the Andean convergent margin (Argentinian backarc of the Central Volcanic Zone), as well as the plume-influenced spreading center in Iceland. All assemblies contain two orders of magnitude more peptidases than CAZymes, suggesting that the microorganisms more often use proteins for their carbon and/or nitrogen acquisition instead of complex sugars. The CAZy families in highest abundance are GH23 and CBM50, and the most abundant peptidase families are M23 and C26, all four of which degrade peptidoglycan found in bacterial cells. This implies that the heterotrophic community relies on autochthonous dead cell biomass, rather than allochthonous plant matter, for organic material. Enzymes involved in the degradation of cyanobacterial- and algal-derived compounds are in lower abundance at every site, with volcanic sites having more enzymes degrading cyanobacterial compounds and non-volcanic sites having more enzymes degrading algal compounds. Activity assays showed that many of these enzyme classes are active in these samples. High temperature sites (> 80°C) had similar extracellular carbon-degrading enzymes regardless of their province, suggesting a less well-developed population of secondary consumers at these sites, possibly connected with the limited extent of the subsurface biosphere in these high temperature sites. We conclude that in < 80°C springs, chemolithoautotrophic production supports heterotrophs capable of degrading a wide range of organic compounds that do not vary by geological province, even though the taxonomic and respiratory repertoire of chemolithoautotrophs and heterotrophs differ greatly across these regions.

Lloyd Karen G.

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