scholarly journals Ammonia-Oxidizing β-Proteobacteria from the Oxygen Minimum Zone off Northern Chile

2007 ◽  
Vol 73 (11) ◽  
pp. 3547-3555 ◽  
Author(s):  
Verónica Molina ◽  
Osvaldo Ulloa ◽  
Laura Farías ◽  
Homero Urrutia ◽  
Salvador Ramírez ◽  
...  
Keyword(s):  
16S Rrna ◽  
Waste Treatment ◽  
Treatment Plant ◽  
Oxygen Minimum Zone ◽  
Rrna Gene ◽  
Ammonia Oxidizing Bacteria ◽  
Northern Chile ◽  
Clone Libraries ◽  
Minimum Zone ◽  
Oxygen Minimum

ABSTRACT The composition of ammonia-oxidizing bacteria from the β-Proteobacteria subclass (βAOB) was studied in the surface and upper-oxycline oxic waters (2- to 50-m depth, ∼200 to 44 μM O2) and within the oxygen minimum zone (OMZ) suboxic waters (50- to 400-m depth, ≤10 μM O2) of the eastern South Pacific off northern Chile. This study was carried out through cloning and sequencing of genes coding for 16S rRNA and the ammonia monooxygenase enzyme active subunit (amoA). Sequences affiliated with Nitrosospira-like cluster 1 dominated the 16S rRNA gene clone libraries constructed from both oxic and suboxic waters. Cluster 1 consists exclusively of yet-uncultivated βAOB from marine environments. However, a single clone, out of 224 obtained from the OMZ, was found to belong to Nitrosospira lineage cluster 0. To our knowledge, cluster 0 sequences have been derived from βAOB isolated only from sand, soil, and freshwater environments. Sequences in clone libraries of the amoA gene from the surface and upper oxycline could be grouped in a marine subcluster, also containing no cultured representatives. In contrast, all 74 amoA sequences originating from the OMZ were either closely affiliated with cultured Nitrosospira spp. from clusters 0 and 2 or with other yet-uncultured βAOB from soil and an aerated-anoxic Orbal process waste treatment plant. Our results reveal the presence of Nitrosospira-like βAOB in both oxic and suboxic waters associated with the OMZ but with a clear community shift at the functional level (amoA) along the strong oxygen gradient.

scholarly journals Benthic archaea as potential sources of tetraether membrane lipids in sediments across an oxygen minimum zone

2018 ◽  
Vol 15 (13) ◽  
pp. 4047-4064 ◽  
Author(s):  
Marc A. Besseling ◽  
Ellen C. Hopmans ◽  
R. Christine Boschman ◽  
Jaap S. Sinninghe Damsté ◽  
Laura Villanueva
Keyword(s):  
16S Rrna ◽  
Relative Abundance ◽  
Surface Sediments ◽  
Membrane Lipids ◽  
Oxygen Minimum Zone ◽  
Rrna Gene ◽  
Polar Head Group ◽  
Group I ◽  
Minimum Zone ◽  
Oxygen Minimum

Abstract. Benthic archaea comprise a significant part of the total prokaryotic biomass in marine sediments. Recent genomic surveys suggest they are largely involved in anaerobic processing of organic matter, but the distribution and abundance of these archaeal groups are still largely unknown. Archaeal membrane lipids composed of isoprenoid diethers or tetraethers (glycerol dibiphytanyl glycerol tetraether, GDGT) are often used as archaeal biomarkers. Here, we compare the archaeal diversity and intact polar lipid (IPL) composition in both surface (0–0.5 cm) and subsurface (10–12 cm) sediments recovered within, just below, and well below the oxygen minimum zone (OMZ) of the Arabian Sea. Archaeal 16S rRNA gene amplicon sequencing revealed a predominance of Thaumarchaeota (Marine Group I, MG-I) in oxygenated sediments. Quantification of archaeal 16S rRNA and ammonia monoxygenase (amoA) of Thaumarchaeota genes and their transcripts indicated the presence of an active in situ benthic population, which coincided with a high relative abundance of hexose phosphohexose crenarchaeol, a specific biomarker for living Thaumarchaeota. On the other hand, anoxic surface sediments within the OMZ and all subsurface sediments were dominated by archaea belonging to the Miscellaneous Crenarchaeota Group (MCG), the Thermoplasmatales and archaea of the DPANN (superphylum grouping Micrarchaeota, Diapherotrites, Aenigmarchaeota, Nanohaloarchaeota, Parvarchaeota, Nanoarchaeota, Pacearchaeota and Woesearchaeota). Members of the MCG were diverse, with a dominance of subgroup MCG-12 in anoxic surface sediments. This coincided with a high relative abundance of IPL GDGT-0 with an unknown polar head group. Subsurface anoxic sediments were characterized by higher relative abundance of GDGT-0, -2 and -3 with dihexose IPL types, GDGT-0 with a cyclopentanetetraol molecule and hexose, as well as the presence of specific MCG subgroups, suggesting that these groups could be the biological sources of these archaeal lipids.

scholarly journals Benthic Archaea as potential sources of tetraether membrane lipids in sediments across an oxygen minimum zone

2017 ◽  
Author(s):  
Marc A. Besseling ◽  
Ellen C. Hopmans ◽  
Jaap S. Sinninghe Damsté ◽  
Laura Villanueva
Keyword(s):  
16S Rrna ◽  
Relative Abundance ◽  
Surface Sediments ◽  
Membrane Lipids ◽  
Oxygen Minimum Zone ◽  
Rrna Gene ◽  
Polar Head Group ◽  
Group I ◽  
Minimum Zone ◽  
Oxygen Minimum

Abstract. Benthic Archaea comprise a significant part of the total prokaryotic biomass in marine sediments. Recent genomic surveys suggest they are largely involved in anaerobic processing of organic matter but the distribution and abundance of these archaeal groups is still largely unknown. Archaeal membrane lipids composed of isoprenoid diethers or tetraethers (glycerol dibiphytanyl glycerol tetraether, GDGT) are often used as archaeal biomarkers. Here, we compare the archaeal diversity and intact polar lipid (IPL) composition in both surface (0–0.5 cm) and subsurface (10–12 cm) sediments recovered within, just below, and well below the oxygen minimum zone (OMZ) of the Arabian Sea. Archaeal 16S rRNA gene amplicon sequencing revealed a predominance of Thaumarchaeota (Marine Group I, MG-I) in oxygenated sediments. Quantification of archaeal 16S rRNA and ammonia monoxygenase (amoA) of Thaumarchaeota genes and their transcripts indicated the presence of an active in situ benthic population, which coincided with a high relative abundance of hexose phosphohexose crenarchaeol, a specific biomarker for living Thaumarchaeota. On the other hand, anoxic surface sediments within the OMZ and all subsurface sediments were dominated by archaea belonging to the Miscellaneous Crenarchaeota Group (MCG), the Thermoplasmatales and archaea of the DPANN superphylum. Members of the MCG were diverse with a dominance of subgroup MCG-12 in anoxic surface sediments. This coincided with a high relative abundance of IPL GDGT-0 with an unknown polar head group. Subsurface anoxic sediments were characterized by higher relative abundance of GDGT-0, 2 and 3 with dihexose IPL-types, as well as GDGT-0 with a cyclopentanetetraol molecule and a hexose, as well as the presence of specific MCG subgroups, suggesting that these groups could be the biological sources of these archaeal lipids.

scholarly journals Zooplankton diel vertical migration and downward C flux into the oxygen minimum zone in the highly productive upwelling region off northern Chile

2020 ◽  
Vol 17 (2) ◽  
pp. 455-473 ◽  
Author(s):  
Pritha Tutasi ◽  
Ruben Escribano
Keyword(s):  
Vertical Migration ◽  
Diel Vertical Migration ◽  
Net Primary Production ◽  
Oxygen Minimum Zone ◽  
Zooplankton Biomass ◽  
Taxonomic Structure ◽  
Northern Chile ◽  
Minimum Zone ◽  
The Impact ◽  
Oxygen Minimum

Abstract. Diel vertical migration (DVM) can enhance the vertical flux of carbon (C), and so contributes to the functioning of the biological pump in the ocean. The magnitude and efficiency of this active transport of C may depend on the size and taxonomic structure of the migrant zooplankton. However, the impact that a variable community structure can have on zooplankton-mediated downward C flux has not been properly addressed. This taxonomic effect may become critically important in highly productive eastern boundary upwelling systems (EBUSs), where high levels of zooplankton biomass are found in the coastal zone and are composed by a diverse community with variable DVM behavior. In these systems, presence of a subsurface oxygen minimum zone (OMZ) can impose an additional constraint to vertical migration and so influence the downward C export. Here, we address these issues based on a vertically stratified zooplankton sampling at three stations off northern Chile (20–30∘ S) during November–December 2015. Automated analysis of zooplankton composition and taxa-structured biomass allowed us to estimate daily migrant biomass by taxa and their amplitude of migration. We found that a higher biomass aggregates above the oxycline, associated with more oxygenated surface waters and this was more evident upon a more intense OMZ. Some taxonomic groups, however, were found closely associated with the OMZ. Most taxa were able to perform DVM in the upwelling zone withstanding severe hypoxia. Also, strong migrants, such as eucalanid copepods and euphausiids, can exhibit a large migration amplitude (∼500 m), remaining either temporarily or permanently within the core of the OMZ and thus contributing to the release of C below the thermocline. Our estimates of DVM-mediated C flux suggested that a mean migrant biomass of ca. 958 mg C m−2 d−1 may contribute with about 71.3 mg C m−2 d−1 to the OMZ system through respiration, mortality and C excretion at depth, accounting for ca. 4 % of the net primary production, and so implies the existence of an efficient mechanism to incorporate freshly produced C into the OMZ. This downward C flux mediated by zooplankton is however spatially variable and mostly dependent on the taxonomic structure due to variable migration amplitude and DVM behavior.

Anammox bacteria and the anaerobic oxidation of ammonium in the oxygen minimum zone off northern Chile

2009 ◽  
Vol 56 (16) ◽  
pp. 1021-1031 ◽  
Author(s):  
Alexander Galán ◽  
Verónica Molina ◽  
Bo Thamdrup ◽  
Dagmar Woebken ◽  
Gaute Lavik ◽  
...  
Keyword(s):  
Oxygen Minimum Zone ◽  
Anammox Bacteria ◽  
Northern Chile ◽  
Anaerobic Oxidation ◽  
Minimum Zone ◽  
Oxygen Minimum

scholarly journals Ammonium cycling under a strong oxygen gradient associated with the Oxygen Minimum Zone off northern Chile (~23°S)

2005 ◽  
Vol 288 ◽  
pp. 35-43 ◽  
Author(s):  
V Molina ◽  
L Farías ◽  
Y Eissler ◽  
LA Cuevas ◽  
CE Morales ◽  
...  
Keyword(s):  
Oxygen Minimum Zone ◽  
Northern Chile ◽  
Oxygen Gradient ◽  
Minimum Zone ◽  
Oxygen Minimum

scholarly journals Underwater Glider Observations in the Oxygen Minimum Zone off Central Chile

2016 ◽  
Vol 97 (10) ◽  
pp. 1783-1789 ◽  
Author(s):  
Oscar Pizarro ◽  
Nadin Ramírez ◽  
Manuel I. Castillo ◽  
Ursula Cifuentes ◽  
Winston Rojas ◽  
...  
Keyword(s):  
Low Frequency ◽  
Oxygen Minimum Zone ◽  
Northern Chile ◽  
Underwater Glider ◽  
Central Chile ◽  
Southern Patagonia ◽  
Minimum Zone ◽  
Frequency Changes ◽  
Oxygen Minimum ◽  
Future Plans

Abstract Gliders have become an efficient and reliable oceanographic platform for measuring physical and biogeochemical properties of the seawater, and the global glider fleet is rapidly expanding. In Chile, glider observations have been carried out in very different oceanographic environments, from the mild upwelling region of subtropical northern Chile to the channels of southern Patagonia. Herein, we briefly present observations and results obtained in the oxygen minimum zone off Concepcion (∼36°30′S). Many new features have been observed in this region thanks to the relatively high resolution of the glider measurements. Future plans for the glider program include an oceanic time series off central Chile that will contribute to the regional observing system of the ocean and allow evaluations of low-frequency changes like those associated with El Niño and La Niña events.

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