@article {ISI:000295971300003,
	title = {{Bacterial sulfur cycling shapes microbial communities in surface sediments of an ultramafic hydrothermal vent field}},
	journal = {ENVIRONMENTAL MICROBIOLOGY},
	volume = {13},
	number = {10},
	year = {2011},
	month = {oct},
	pages = {2633{\textendash}2648},
	type = {Article},
	abstract = {The ultramafic-hosted Logatchev hydrothermal field (LHF) is characterized by vent fluids, which are enriched in dissolved hydrogen and methane compared with fluids from basalt-hosted systems. Thick sediment layers in LHF are partly covered by characteristic white mats. In this study, these sediments were investigated in order to determine biogeochemical processes and key organisms relevant for primary production. Temperature profiling at two mat-covered sites showed a conductive heating of the sediments. Elemental sulfur was detected in the overlying mat and metal-sulfides in the upper sediment layer. Micro-profiles revealed an intensive hydrogen sulfide flux from deeper sediment layers. Fluorescence in situ hybridization showed that filamentous and vibrioid, Arcobacter-related Epsilonproteobacteria dominated the overlying mats. This is in contrast to sulfidic sediments in basalt-hosted fields where mats of similar appearance are composed of large sulfur-oxidizing Gammaproteobacteria. Epsilonproteobacteria (7-21{\%}) and Deltaproteobacteria (20-21{\%}) were highly abundant in the surface sediment layer. The physiology of the closest cultivated relatives, revealed by comparative 16S rRNA sequence analysis, was characterized by the capability to metabolize sulfur components. High sulfate reduction rates as well as sulfide depleted in (34)S further confirmed the importance of the biogeochemical sulfur cycle. In contrast, methane was found to be of minor relevance for microbial life in mat-covered surface sediments. Our data indicate that in conductively heated surface sediments microbial sulfur cycling is the driving force for bacterial biomass production although ultramafichosted systems are characterized by fluids with high levels of dissolved methane and hydrogen.},
	keywords = {ROV Jason (Remotely Operated Vehicle)},
	issn = {1462-2912},
	doi = {10.1111/j.1462-2920.2011.02530.x},
	author = {Schauer, Regina and Roy, Hans and Augustin, Nico and Gennerich, Hans-Hermann and Peters, Marc and Wenzhoefer, Frank and Amann, Rudolf and Meyerdierks, Anke}
}
@article {ISI:000292610200001,
	title = {{Deciphering the ocean bottom pressure variation in the Logatchev hydrothermal field at the eastern flank of the Mid-Atlantic Ridge}},
	journal = {GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS},
	volume = {12},
	year = {2011},
	month = {jul},
	type = {Article},
	abstract = {Ocean bottom pressure data from the Logatchev hydrothermal field (LHF) are presented and analyzed. The data were collected with two ocean bottom pressure meters (OBPs), constructed at the University of Bremen, that are capable of recording signals with frequencies up to 0.25 Hz. Over the long-term, a nearly 2.5 kPa (25 cm water column equivalent) pressure variation over 3.7 years is observed, which is consistent with uplift followed by subsidence, but cannot unequivocally be discerned from instrumental drift. Medium-term pressure variations are compared with satellite surface topography, satellite gravity, ocean modeling, and in situ data from an OBP 700 km away. It is shown that fluctuations in the oceanic mass distribution dominate the variations in this frequency range and that oceanic modeling and data from a 700 km distant OBP are positively correlated with the LHF bottom pressure time series. The short-term variations are dominated by microseisms originating from sea surface waves and pressure waves from earthquakes as can be shown by comparison with weather buoy and teleseismic data.},
	keywords = {ROV Jason (Remotely Operated Vehicle)},
	issn = {1525-2027},
	doi = {10.1029/2010GC003441},
	author = {Gennerich, Hans-Hermann and Villinger, Heinrich}
}
@article {ISI:000295134600001,
	title = {{In situ measurements of hydrogen sulfide, oxygen, and temperature in diffuse fluids of an ultramafic-hosted hydrothermal vent field (Logatchev, 14 degrees 45 {\textquoteleft} N, Mid-Atlantic Ridge): Implications for chemosymbiotic bathymodiolin mussels}},
	journal = {GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS},
	volume = {12},
	year = {2011},
	month = {sep},
	type = {Article},
	abstract = {The Logatchev hydrothermal vent field (14 degrees 45{\textquoteright}N, Mid-Atlantic Ridge) is located in a ridge segment characterized by mantle-derived ultramafic outcrops. Compared to basalt-hosted vents, Logatchev high-temperature fluids are relatively low in sulfide indicating that the diffuse, low-temperature fluids of this vent field may not contain sufficient sulfide concentrations to support a chemosymbiotic invertebrate community. However, the high abundances of bathymodiolin mussels with bacterial symbionts related to free-living sulfur-oxidizing bacteria suggested that bioavailable sulfide is present at Logatchev. To clarify, if diffuse fluids above mussel beds of Bathymodiolus puteoserpentis provide the reductants and oxidants needed by their symbionts for aerobic sulfide oxidation, in situ microsensor measurements of dissolved hydrogen sulfide and oxygen were combined with simultaneous temperature measurements. High temporal fluctuations of all three parameters were measured above the mussel beds. H2S and O-2 coexisted with mean concentrations between 9 and 31 mu M (H2S) and 216 and 228 mu M (O-2). Temperature maxima ({\textless}= 7.4 degrees C) were generally concurrent with H2S maxima ({\textless}= 156 mu M) and O-2 minima ({\textgreater}= 142 mu M). Long-term measurements for 250 days using temperature as a proxy for oxygen and sulfide concentrations indicated that the mussels were neither oxygen limited nor sulfide limited. Our in situ measurements at Logatchev indicate that sulfide may also be bioavailable in diffuse fluids from other ultramafic-hosted vents along slow and ultraslow spreading ridges. Components: 12,100 words, 9 figures, 4 tables.},
	keywords = {ROV Jason (Remotely Operated Vehicle)},
	issn = {1525-2027},
	doi = {10.1029/2011GC003632},
	author = {Zielinski, Frank U and Gennerich, Hans-Hermann and Borowski, Christian and Wenzhoefer, Frank and Dubilier, Nicole}
}
