scholarly journals Community composition of ammonia-oxidizing archaea from surface and anoxic depths of oceanic oxygen minimum zones

2013 ◽  
Vol 4 ◽  
Author(s):  
Xuefeng Peng ◽  
Amal Jayakumar ◽  
Bess B. Ward
Keyword(s):  
Community Composition ◽  
Oxygen Minimum Zones ◽  
Ammonia Oxidizing Archaea ◽  
Oxygen Minimum

scholarly journals Confounding effects of oxygen and temperature on the TEX86signature of marine Thaumarchaeota

2015 ◽  
Vol 112 (35) ◽  
pp. 10979-10984 ◽  
Author(s):  
Wei Qin ◽  
Laura T. Carlson ◽  
E. Virginia Armbrust ◽  
Allan H. Devol ◽  
James W. Moffett ◽  
...  
Keyword(s):  
Membrane Lipids ◽  
Marine Microorganisms ◽  
Low Oxygen ◽  
Oxygen Minimum Zones ◽  
Surface Ocean ◽  
Ammonia Oxidizing Archaea ◽  
Compositional Changes ◽  
Response To Temperature ◽  
Incubation Temperatures ◽  
Oxygen Minimum

Marine ammonia-oxidizing archaea (AOA) are among the most abundant of marine microorganisms, spanning nearly the entire water column of diverse oceanic provinces. Historical patterns of abundance are preserved in sediments in the form of their distinctive glycerol dibiphytanyl glycerol tetraether (GDGT) membrane lipids. The correlation between the composition of GDGTs in surface sediment and the overlying annual average sea surface temperature forms the basis for a paleotemperature proxy (TEX86) that is used to reconstruct surface ocean temperature as far back as the Middle Jurassic. However, mounting evidence suggests that factors other than temperature could also play an important role in determining GDGT distributions. We here use a study set of four marine AOA isolates to demonstrate that these closely related strains generate different TEX86–temperature relationships and that oxygen (O2) concentration is at least as important as temperature in controlling TEX86values in culture. All of the four strains characterized showed a unique membrane compositional response to temperature, with TEX86-inferred temperatures varying as much as 12 °C from the incubation temperatures. In addition, both linear and nonlinear TEX86–temperature relationships were characteristic of individual strains. Increasing relative abundance of GDGT-2 and GDGT-3 with increasing O2limitation, at the expense of GDGT-1, led to significant elevations in TEX86-derived temperature. Although the adaptive significance of GDGT compositional changes in response to both temperature and O2is unclear, this observation necessitates a reassessment of archaeal lipid-based paleotemperature proxies, particularly in records that span low-oxygen events or underlie oxygen minimum zones.

scholarly journals Diversity and distribution of nitrogen fixation genes in the oxygen minimum zones of the world oceans

2020 ◽  
Vol 17 (23) ◽  
pp. 5953-5966
Author(s):  
Amal Jayakumar ◽  
Bess B. Ward
Keyword(s):  
Community Composition ◽  
Surface Waters ◽  
World Ocean ◽  
Operational Taxonomic Unit ◽  
N Fixation ◽  
Oxygen Minimum Zones ◽  
Abundant Otus ◽  
The World ◽  
Nifh Genes ◽  
Oxygen Minimum

Abstract. Diversity and community composition of nitrogen (N) fixing microbes in the three main oxygen minimum zones (OMZs) of the world ocean were investigated using operational taxonomic unit (OTU) analysis of nifH clone libraries. Representatives of three of the four main clusters of nifH genes were detected. Cluster I sequences were most diverse in the surface waters, and the most abundant OTUs were affiliated with Alpha- and Gammaproteobacteria. Cluster II, III, and IV assemblages were most diverse at oxygen-depleted depths, and none of the sequences were closely related to sequences from cultivated organisms. The OTUs were biogeographically distinct for the most part – there was little overlap among regions, between depths, or between cDNA and DNA. In this study of all three OMZ regions, as well as from the few other published reports from individual OMZ sites, the dominance of a few OTUs was commonly observed. This pattern suggests the dynamic response of the components of the overall diverse assemblage to variable environmental conditions. Community composition in most samples was not clearly explained by environmental factors, but the most abundant OTUs were differentially correlated with the obvious variables, temperature, salinity, oxygen, and nitrite concentrations. Only a few cyanobacterial sequences were detected. The prevalence and diversity of microbes that harbor nifH genes in the OMZ regions, where low rates of N fixation are reported, remains an enigma.

scholarly journals In situ quantification of ultra‐low O 2 concentrations in oxygen minimum zones: Application of novel optodes

2016 ◽  
Vol 14 (12) ◽  
pp. 784-800 ◽  
Author(s):  
Morten Larsen ◽  
Philipp Lehner ◽  
Sergey M. Borisov ◽  
Ingo Klimant ◽  
Jan P. Fischer ◽  
...  
Keyword(s):  
Oxygen Minimum Zones ◽  
Oxygen Minimum

scholarly journals Expanded oxygen minimum zones during the late Paleocene-early Eocene: Hints from multiproxy comparison and ocean modeling

2016 ◽  
Vol 31 (12) ◽  
pp. 1532-1546 ◽  
Author(s):  
X. Zhou ◽  
E. Thomas ◽  
A. M. E. Winguth ◽  
A. Ridgwell ◽  
H. Scher ◽  
...  
Keyword(s):  
Ocean Modeling ◽  
Early Eocene ◽  
Oxygen Minimum Zones ◽  
Late Paleocene ◽  
Oxygen Minimum

scholarly journals Toward a global calibration for quantifying past oxygenation in oxygen minimum zones using benthic Foraminifera

2021 ◽  
Author(s):  
Martin Tetard ◽  
Laetitia Licari ◽  
Kazuyo Tachikawa ◽  
Ekaterina Ovsepyan ◽  
Luc Beaufort
Keyword(s):  
North Pacific ◽  
Transfer Functions ◽  
Late Quaternary ◽  
Global Climate ◽  
Single Species ◽  
Pore Waters ◽  
Oxygen Minimum Zones ◽  
Global Calibration ◽  
Circularity Index ◽  
Oxygen Minimum

Abstract. Oxygen Minimum Zones (OMZs) are oceanic areas largely depleted in dissolved oxygen, nowadays considered in expansion in the face of global warming. Their ecological and economic consequences are being debated. The investigation of past OMZ conditions allows us to better understand biological and physical mechanisms responsible for their variability with regards to climate change, carbon pump and carbonate system. To investigate the relationship between OMZ expansion and global climate changes during the late Quaternary, quantitative oxygen reconstructions are needed, but are still in their early development. Here, past bottom water oxygenation (BWO) was quantitatively assessed through a new, fast, semi-automated, and taxonfree morphometric analysis of benthic foraminiferal tests, developed and calibrated using Eastern North Pacific (ENP) and the Eastern South Pacific (ESP) OMZs samples. This new approach is based on an average size and circularity index for each sample. This method, as well as two already published micropalaeontological approaches based on benthic foraminiferal assemblages variability and porosity investigation of a single species, were here calibrated based on availability of new data from 23 core tops recovered along an oxygen gradient (from 0.03 to 1.79 mL.L−1) from the ENP, ESP, AS (Arabian Sea) and WNP (Western North Pacific, including its marginal seas) OMZs. Global calibrated transfer functions are thus herein proposed for each of these methods. These micropalaeontological reconstruction approaches were then applied on a paleorecord from the ENP OMZ to examine the consistency and limits of these methods, as well as the relative influence of bottom and pore waters on these micropalaeontological tools. Both the assemblages and morphometric approaches (that is also ultimately based on the ecological response of the complete assemblage and faunal succession according to BWO) gave similar and consistent past BWO reconstructions, while the porosity approach (based on a single species and its unique response to a mixed signal of bottom and pore waters) shown ambiguous estimations.

scholarly journals Modulation of the vertical particles transfer efficiency in the Oxygen Minimum Zone off Peru

2018 ◽  
Author(s):  
Marine Bretagnon ◽  
Aurélien Paulmier ◽  
Véronique Garçon ◽  
Boris Dewitte ◽  
Sérena Illig ◽  
...  
Keyword(s):  
Organic Matter ◽  
Water Column ◽  
Sediment Traps ◽  
Biogeochemical Cycles ◽  
High Temporal Resolution ◽  
Oxygen Minimum Zones ◽  
Marine Life ◽  
Minimum Zone ◽  
Earth’S System ◽  
Oxygen Minimum

Abstract. The fate of the Organic Matter (OM) produced by marine life controls the major biogeochemical cycles of the Earth’s system. The OM produced through photosynthesis is either preserved, exported towards sediments or degraded through remineralisation in the water column. The productive Eastern Boundary Upwelling Systems (EBUSs) associated with Oxygen Minimum Zones (OMZs) should foster OM preservation due to low O2 conditions, but their intense and diverse microbial activity should enhance OM degradation. To investigate this contradiction, sediment traps were deployed near the oxycline and in the OMZ core on an instrumented moored line off Peru, providing high temporal resolution O2 series characterizing two seasonal steady states at the upper trap: suboxic ([O2] 

scholarly journals Anthropogenic carbon in the eastern South Pacific Ocean

2007 ◽  
Vol 4 (3) ◽  
pp. 1815-1837 ◽  
Author(s):  
L. Azouzi ◽  
R. Gonçalves Ito ◽  
F. Touratier ◽  
C. Goyet
Keyword(s):  
Pacific Ocean ◽  
General Trend ◽  
South Pacific ◽  
Hydrodynamic Characteristics ◽  
Eastern Pacific Ocean ◽  
Previous Knowledge ◽  
Oxygen Minimum Zones ◽  
South Pacific Ocean ◽  
Anthropogenic Carbon ◽  
Oxygen Minimum

Abstract. We present results from the BIOSOPE cruise in the eastern South Pacific Ocean. In particular, we present estimates of the anthropogenic carbon CantTrOCA distribution in this area using the TrOCA method recently developed by Touratier and Goyet (2004a, b) and Touratier et al. (2007). We study the distribution of this anthropogenic carbon taking into account of the hydrodynamic characteristics of this region. We then compare these results with earlier estimates in nearby areas of the anthropogenic carbon as well as other anthropogenic tracer (CFC-11). The highest concentrations of CantTrOCA are located around 13° S 132° W and 32° S 91° W, and their concentrations are larger than 80 μmol kg−1 and 70 μmol kg−1, respectively. The lowest concentrations were observed below 800 m depths (≤2 μ mol kg−1) and at the Oxygen Minimum Zones (OMZ), mainly around 140° W (<11 μmol kg−1). The comparison with earlier work in nearby areas provides a general trend and indicates that the results presented here are in general agreement with previous knowledge. This work further improves our understanding on the penetration of anthropogenic carbon in the eastern Pacific Ocean.

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