@article {ISI:000360888000001,
	title = {{Carbon fixation by basalt-hosted microbial communities}},
	journal = {FRONTIERS IN MICROBIOLOGY},
	volume = {6},
	year = {2015},
	month = {sep},
	type = {Article},
	abstract = {Oceanic crust is a massive potential habitat for microbial life on Earth, yet our understanding of this ecosystem is limited due to difficulty in access. In particular, measurements of rates of microbial activity are sparse. We used stable carbon isotope incubations of crustal samples, coupled with functional gene analyses, to examine the potential for carbon fixation on oceanic crust. Both seafloor-exposed and subseafloor basalts were recovered from different mid-ocean ridge and hot spot environments (i.e., the Juan de Fuca Ridge, the Mid-Atlantic Ridge, and the Loihi Seamount) and incubated with C-13-labeled bicarbonate. Seafloor-exposed basalts revealed incorporation of C-13-label into organic matter over time, though the degree of incorporation was heterogeneous. The incorporation of C-13 into biomass was inconclusive in subseafloor basalts. Translating these measurements into potential rates of carbon fixation indicated that 0.1-10 nmol C g(-1) rock d(-1) could be fixed by seafloor-exposed rocks. When scaled to the global production of oceanic crust, this suggests carbon fixation rates of 10(9)-10(12) g C year(-1), which matches earlier predictions based on thermodynamic calculations. Functional gene analyses indicate that the Calvin cycle is likely the dominant biochemical mechanism for carbon fixation in basalt-hosted biofilms, although the reductive acetyl-CoA pathway and reverse TCA cycle likely play some role in net carbon fixation. These results provide empirical evidence for autotrophy in oceanic crust, suggesting that basalt-hosted autotrophy could be a significant contributor of organic matter in this remote and vast environment.},
	keywords = {HOV Alvin (Human Occupied Vehicle), ROV Jason (Remotely Operated Vehicle)},
	issn = {1664-302X},
	doi = {10.3389/fmicb.2015.90400904},
	author = {Orcutt, Beth N and Sylvan, Jason B and Rogers, Daniel R and Delaney, Jennifer and Lee, Raymond W and Girguis, Peter R}
}
@article {ISI:000361984700015,
	title = {{Comparison of Archaeal and Bacterial Diversity in Methane Seep Carbonate Nodules and Host Sediments, Eel River Basin and Hydrate Ridge, USA}},
	journal = {MICROBIAL ECOLOGY},
	volume = {70},
	number = {3},
	year = {2015},
	month = {oct},
	pages = {766{\textendash}784},
	type = {Article},
	abstract = {Anaerobic oxidation of methane (AOM) impacts carbon cycling by acting as a methane sink and by sequestering inorganic carbon via AOM-induced carbonate precipitation. These precipitates commonly take the form of carbonate nodules that form within methane seep sediments. The timing and sequence of nodule formation within methane seep sediments are not well understood. Further, the microbial diversity associated with sediment-hosted nodules has not been well characterized and the degree to which nodules reflect the microbial assemblage in surrounding sediments is unknown. Here, we conducted a comparative study of microbial assemblages in methane-derived authigenic carbonate nodules and their host sediments using molecular, mineralogical, and geochemical methods. Analysis of 16S rRNA gene diversity from paired carbonate nodules and sediments revealed that both sample types contained methanotrophic archaea (ANME-1 and ANME-2) and syntrophic sulfate-reducing bacteria (Desulfobacteraceae and Desulfobulbaceae), as well as other microbial community members. The combination of geochemical and molecular data from Eel River Basin and Hydrate Ridge suggested that some nodules formed in situ and captured the local sediment-hosted microbial community, while other nodules may have been translocated or may represent a record of conditions prior to the contemporary environment. Taken together, this comparative analysis offers clues to the formation regimes and mechanisms of sediment-hosted carbonate nodules.},
	keywords = {HOV Alvin (Human Occupied Vehicle)},
	issn = {0095-3628},
	doi = {10.1007/s00248-015-0615-6},
	author = {Mason, Olivia U and Case, David H and Naehr, Thomas H and Lee, Raymond W and Thomas, Randal B and Bailey, Jake V and Orphan, Victoria J}
}
@article {ISI:000332225300011,
	title = {{Spatial patterns of tissue stable isotope contents give insight into the nutritional sources for seep communities on the Gulf of Mexico lower slope}},
	journal = {MARINE ECOLOGY PROGRESS SERIES},
	volume = {498},
	year = {2014},
	pages = {133{\textendash}U481},
	type = {Article},
	abstract = {In this study, we present the first thorough trophic characterization of cold seep macrofaunal communities on the Gulf of Mexico lower continental slope ({\textgreater} 1000 m depth). We analyzed tissue delta C-13, delta N-15, and delta S-34 of vestimentiferan tubeworms, bathymodiolin mussels, vesicomyid clams, and their associated macrofaunal communities from discrete collections made across the entire lower slope. Over half of macrofauna associated with mussels and about half associated with vestimentiferans had delta C-13 values below -45{\%}. We also observed high spatial variability in the delta C-13 values of entire local communities, and the delta C-13 of associated fauna were significantly correlated with the delta C-13 compositions of the symbiotic species from the same location. These data indicate widespread incorporation of methane-derived carbon in mussel and vestimentiferan communities. This finding was particularly surprising in communities associated with older vestimentiferans, given the low rates of seepage observed in similar communities on the upper slope. On average, delta N-13 values in mussels and their associates were significantly more depleted and more variable than vestimentiferans, clams, and their associates, and there was a significant linear relationship between tissue delta N-15 values of mussels and their associated communities. The tissue delta S-34 values in macrofauna associated with vestimentiferans were more variable and significantly more depleted than mussel associates (delta S-34 = -16.8 to + 19.1{\%} for vestimentiferan associates and delta S-34 = -3.1 to + 20.8{\%} for mussel associates), consistent with higher isotopic fractionation during sulfate reduction in vestimentiferan habitats and a potentially higher nutritional contribution of sulfide-derived organic sulfur in vestimentiferan communities.},
	keywords = {HOV Alvin (Human Occupied Vehicle), ROV Jason (Remotely Operated Vehicle)},
	issn = {0171-8630},
	doi = {10.3354/meps10598},
	author = {Becker, Erin L and Cordes, Erik E and Macko, Stephen A and Lee, Raymond W and Fisher, Charles R}
}
@article {ISI:000326430500019,
	title = {{Activity and positioning of eurythermal hydrothermal vent sulphide worms in a variable thermal environment}},
	journal = {JOURNAL OF EXPERIMENTAL MARINE BIOLOGY AND ECOLOGY},
	volume = {448},
	year = {2013},
	month = {oct},
	pages = {149{\textendash}155},
	type = {Article},
	abstract = {Here we investigate behavioral responses to fine-scale spatial and temporal temperature gradients in a heat tolerant hydrothermal vent worm (Paralvinella sulfincola). While this species has been a model organism for understanding physiological adaptations to extreme environments, lacking are corroborative in situ experiments and characterization of temperature-related behaviors representing the lower thermal tolerance range of this species. To address this knowledge gap, we first quantified the upper thermal limit for this species using a rapid heating protocol executed remotely on the seafloor. Second, we used a combination of in situ observations and shipboard experiments to test for temperature-dependent patterns in activity and behavior. We confirm that P. sulfincola is remarkably eurythermal and demonstrates a thermal niche breadth exceeding 45 degrees C. We further show that the activity and positioning of worms relate to temperatures within its lower preferred range (i.e., between 4 and 20 degrees C). Worms tended to remain closer to their tube openings and held their branchial crown in a consistent location when fluids were relatively warm. By contrast, when fluids were cooler, both the distance worms were observed from their tubes and positioning of their branchial crown were more variable. A Bayesian hidden Markov model classified each worm at each time interval as being in a high or low activity state according to the magnitude of change in their orientation and how far they moved between successive time lapse images. We found that the transition between active and inactive states at any time period is related to fluid temperature. Our observations indicate that the behavior of the worms is temperature-dependent, which may in turn reflect temperature-related variables such as the delivery of food particles, dissolved oxygen concentration, or relative environmental variability. Our findings demonstrate that this species can respond behaviorally to very fine-scale environmental variability in a manner not simply predicted by models of increasing activity with temperature. (C) 2013 Elsevier B.V. All rights reserved.},
	keywords = {HOV Alvin (Human Occupied Vehicle)},
	issn = {0022-0981},
	doi = {10.1016/j.jembe.2013.06.015},
	author = {Bates, Amanda E and Bird, Tomas J and Robert, Katleen and Onthank, Kirt L and Quinn, Gerry P and Juniper, S Kim and Lee, Raymond W}
}
