scholarly journals Temporal and vertical variability of bacterioplankton composition in Chipana bay (21º20’S) in a coastal upwelling system of northern Chile: A fluorescence in situ hybridization approach

2020 ◽  
Vol 55 (1) ◽  
pp. 47
Author(s):  
Cristy Medina-Armijo ◽  
Rubén Moraga-Mamani ◽  
Edgardo Santander-Pulgar
Keyword(s):  
In Situ Hybridization ◽  
Coastal Upwelling ◽  
Surface Layers ◽  
Gamma Proteobacteria ◽  
Minimum Zone ◽  
Taxonomic Groups ◽  
Alpha Proteobacteria ◽  
The Vertical Distribution ◽  
Oxygen Minimum

The bacterioplankton in the upwelling systems associated with oceanographic condition of the oxygen minimum zone (OMZ) of the Eastern tropical South Pacific was studied through visualization and enumeration with fluorescent in situ hybridization (FISH). Six different taxonomic groups were studied (Alpha, Beta, Gamma-proteobacteria, Cytophaga-flavobacterium and the domains Archaea and Bacteria). The analysis showed a greater predominance of the Bacteria domain (20 to 68% of hybridized cells) over Archaea (2 to 18% of hybridized cells). The specific groups showed that Cytophaga-flavobacterium, Alpha-proteobacteria and Gamma-proteobacteria are more abundant in the surface layer. Gamma-proteobacteria is also most abundant in the deep oxycline and, Beta-proteobacteria is the group with the lowest registered abundances. Changes in the vertical distribution of the bacterial community in the water column between OMZ and on oxycline were observed through NMDS. This change is a product of a shift in the abundances of the specific groups Cytophaga-flavobacterium and Gamma-proteobacteria in the surface layers, due to low concentration of chlorophyll-a caused by periods of relaxation in the upwelling. 

scholarly journals Differences between coastal and open ocean distributions of N<sub>2</sub>O in the oxygen minimum zone off Peru

2015 ◽  
Vol 12 (13) ◽  
pp. 10167-10193 ◽  
Author(s):  
A. Kock ◽  
D. L. Arévalo-Martínez ◽  
C. R. Löscher ◽  
H. W. Bange
Keyword(s):  
Linear Relationship ◽  
Coastal Upwelling ◽  
Oxygen Minimum Zone ◽  
Open Ocean ◽  
Oxygen Utilization ◽  
Double Peak Structure ◽  
Peak Structure ◽  
Minimum Zone ◽  
Oxygen Minimum ◽  
Oxygen Concentrations

Abstract. Depth profiles of nitrous oxide (N2O) were measured during six cruises to the upwelling area and oxygen minimum zone (OMZ) off Peru in 2009 and 2012/13, covering both the coastal shelf region and the adjacent open ocean. N2O profiles displayed a strong sensitivity towards oxygen concentrations. Open ocean profiles showed a transition from a broad maximum to a double-peak structure towards the centre of the OMZ where the oxygen minimum was more pronounced. Maximum N2O concentrations in the open ocean were about 80 nM. A linear relationship between ΔN2O and apparent oxygen utilization (AOU) could be found for all measurements within the upper oxycline, with a slope similar to studies in other oceanic regions. N2O profiles close to the shelf revealed a much higher variability, with N2O concentrations in the upper oxycline reaching up to several hundred nanomoles per liter at selected stations. Due to the extremely sharp oxygen gradients at the shelf, these maxima occurred in very shallow water depths of less than 50 m. In this area, a linear relationship between ΔN2O and AOU could not be observed. N2O concentrations above 100 nM were observed at oxygen concentrations ranging from close to saturation to suboxic conditions. Our results indicate that the coastal upwelling off Peru at the shelf causes conditions that lead to extreme N2O accumulation.

scholarly journals The control of hydrogen sulfide on benthic iron and cadmium fluxes in the oxygen minimum zone off Peru

2019 ◽  
Author(s):  
Anna Plass ◽  
Christian Schlosser ◽  
Stefan Sommer ◽  
Andrew W. Dale ◽  
Eric P. Achterberg ◽  
...  
Keyword(s):  
Hydrogen Sulfide ◽  
Trace Metals ◽  
Pore Water ◽  
Oxygen Minimum Zone ◽  
Benthic Fluxes ◽  
Benthic Chamber ◽  
Bottom Waters ◽  
Minimum Zone ◽  
Oxygen Minimum

Abstract. Sediments in oxygen-depleted marine environments can be an important sink or source of bio-essential trace metals in the ocean. However, the key mechanisms controlling the release from or burial of trace metals in sediments are not exactly understood. Here, we investigate the benthic biogeochemical cycling of Fe and Cd in the oxygen minimum zone off Peru. We combine bottom water profiles, pore water profiles, as well as benthic fluxes determined from pore water profiles and in-situ from benthic chamber incubations along a depth transect at 12° S. In agreement with previous studies, both concentration-depth profiles and in-situ benthic fluxes indicate a Fe release from sediments into bottom waters. Diffusive Fe fluxes and Fe fluxes from benthic chamber incubations are roughly consistent (0.3–17.1 mmol m−2 y−1), indicating that diffusion is the main transport mechanism of dissolved Fe across the sediment-water interface. The occurrence of mats of sulfur oxidizing bacteria on the seafloor represents an important control on the spatial distribution of Fe fluxes by regulating hydrogen sulfide (H2S) concentrations and, potentially, Fe sulfide precipitation within the surface sediment. Removal of dissolved Fe after its release to anoxic bottom waters is rapid in the first 4 m away from the seafloor (half-life

scholarly journals Uptake of algal carbon and the likely synthesis of an "essential" fatty acid by <i>Uvigerina</i> ex. gr. <i>semiornata</i> (Foraminifera) within the Pakistan margin oxygen minimum zone: evidence from fatty acid biomarker and <sup>13</sup>C tracer experiments

2014 ◽  
Vol 11 (14) ◽  
pp. 3729-3738 ◽  
Author(s):  
K. E. Larkin ◽  
A. J. Gooday ◽  
C. Woulds ◽  
R. M. Jeffreys ◽  
M. Schwartz ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Food Source ◽  
Benthic Communities ◽  
Oxygen Minimum Zone ◽  
Monsoon Period ◽  
Minimum Zone ◽  
Oxygen Minimum ◽  
Tracer Experiments

Abstract. Foraminifera are an important component of benthic communities in oxygen-depleted settings, where they potentially play a significant role in the processing of organic matter. We tracked the uptake of a 13C-labelled algal food source into individual fatty acids in the benthic foraminiferal species Uvigerina ex. gr. semiornata from the Arabian Sea oxygen minimum zone (OMZ). The tracer experiments were conducted on the Pakistan margin during the late/post monsoon period (August–October 2003). A monoculture of the diatom Thalassiosira weisflogii was 13C-labelled and used to simulate a pulse of phytoplankton in two complementary experiments. A lander system was used for in situ incubations at 140 m water depth and for 2.5 days in duration. Shipboard laboratory incubations of cores collected at 140 m incorporated an oxystat system to maintain ambient dissolved oxygen concentrations and were terminated after 5 days. Uptake of diatoms was rapid, with a high incorporation of diatom fatty acids into foraminifera after ~ 2 days in both experiments. Ingestion of the diatom food source was indicated by the increase over time in the quantity of diatom biomarker fatty acids in the foraminifera and by the high percentage of 13C in many of the fatty acids present at the endpoint of both in situ and laboratory-based experiments. These results indicate that

Contribution of oxygen minimum zone waters to the coastal upwelling off Mauritania

2009 ◽  
Vol 83 (1-4) ◽  
pp. 143-150 ◽  
Author(s):  
Mirjam S. Glessmer ◽  
Carsten Eden ◽  
Andreas Oschlies
Keyword(s):  
Coastal Upwelling ◽  
Oxygen Minimum Zone ◽  
Minimum Zone ◽  
Oxygen Minimum

scholarly journals Cryptic role of tetrathionate in the sulfur cycle: A study from Arabian Sea oxygen minimum zone sediments

2019 ◽  
Author(s):  
Subhrangshu Mandal ◽  
Sabyasachi Bhattacharya ◽  
Chayan Roy ◽  
Moidu Jameela Rameez ◽  
Jagannath Sarkar ◽  
...  
Keyword(s):  
Arabian Sea ◽  
Potential Role ◽  
Sediment Cores ◽  
Oxygen Minimum Zone ◽  
Sulfur Cycle ◽  
Metagenome Analysis ◽  
Minimum Zone ◽  
Oxygen Minimum

ABSTRACTTo explore the potential role of tetrathionate in the sulfur cycle of marine sediments, the population ecology of tetrathionate-forming, oxidizing, and respiring microorganisms was revealed at 15-30 cm resolution along two, ∼3-m-long, cores collected from 530- and 580-mbsl water-depths of Arabian Sea, off India’s west coast, within the oxygen minimum zone (OMZ). Metagenome analysis along the two sediment-cores revealed widespread occurrence of the structural genes that govern these metabolisms; high diversity and relative-abundance was also detected for the bacteria known to render these processes. Slurry-incubation of the sediment-samples, pure-culture isolation, and metatranscriptome analysis, corroborated thein situfunctionality of all the three metabolic-types. Geochemical analyses revealed thiosulfate (0-11.1 μM), pyrite (0.05-1.09 wt %), iron (9232-17234 ppm) and manganese (71-172 ppm) along the two sediment-cores. Pyrites (via abiotic reaction with MnO2) and thiosulfate (via oxidation by chemolithotrophic bacteria prevalentin situ) are apparently the main sources of tetrathionate in this ecosystem. Tetrathionate, in turn, can be either converted to sulfate (via oxidation by the chemolithotrophs present) or reduced back to thiosulfate (via respiration by native bacteria); 0-2.01 mM sulfide present in the sediment-cores may also reduce tetrathionate abiotically to thiosulfate and elemental sulfur. Notably tetrathionate was not detectedin situ- high microbiological and geochemical reactivity of this polythionate is apparently instrumental in the cryptic nature of its potential role as a central sulfur cycle intermediate. Biogeochemical roles of this polythionate, albeit revealed here in the context of OMZ sediments, may well extend to the sulfur cycles of other geomicrobiologically-distinct marine sediment horizons.

scholarly journals Cryptic role of tetrathionate in the sulfur cycle: A study from Arabian Sea oxygen minimum zone sediments

2019 ◽  
Author(s):  
Subhrangshu Mandal ◽  
Sabyasachi Bhattacharya ◽  
Chayan Roy ◽  
Moidu Jameela Rameez ◽  
Jagannath Sarkar ◽  
...  
Keyword(s):  
Arabian Sea ◽  
Potential Role ◽  
Sediment Cores ◽  
Oxygen Minimum Zone ◽  
Sulfur Cycle ◽  
Metagenome Analysis ◽  
Minimum Zone ◽  
Oxygen Minimum

Abstract. To explore the potential role of tetrathionate in the sulfur cycle of marine sediments, the population ecology of tetrathionate-forming, oxidizing, and respiring microorganisms was revealed at 15–30 cm resolution along two, ~ 3-m-long, cores collected from 530- and 580-mbsl water-depths of Arabian Sea, off India’s west coast, within the oxygen minimum zone (OMZ). Metagenome analysis along the two sediment-cores revealed widespread occurrence of the structural genes that govern these metabolisms; high diversity and relative-abundance was also detected for the bacteria known to render these processes. Slurry-incubation of the sediment-samples, pure-culture isolation, and metatranscriptome analysis, corroborated the in situ functionality of all the three metabolic-types. Geochemical analyses revealed thiosulfate (0–11.1 µM), pyrite (0.05–1.09 wt %), iron (9232–17234 ppm) and manganese (71–172 ppm) along the two sediment-cores. Pyrites (via abiotic reaction with MnO2) and thiosulfate (via oxidation by chemolithotrophic bacteria prevalent in situ) are apparently the main sources of tetrathionate in this ecosystem. Tetrathionate, in turn, can be either converted to sulfate (via oxidation by the chemolithotrophs present) or reduced back to thiosulfate (via respiration by native bacteria); 0–2.01 mM sulfide present in the sediment-cores may also reduce tetrathionate abiotically to thiosulfate and elemental sulfur. Notably tetrathionate was not detected in situ – high microbiological and geochemical reactivity of this polythionate is apparently instrumental in the cryptic nature of its potential role as a central sulfur cycle intermediate. Biogeochemical roles of this polythionate, albeit revealed here in the context of OMZ sediments, may well extend to the sulfur cycles of other geomicrobiologically-distinct marine sediment horizons.

scholarly journals ENSO-driven fluctuations in oxygen supply and vertical extent of oxygen-poor waters in the oxygen minimum zone of the Eastern Tropical South Pacific

2019 ◽  
Author(s):  
Yonss Saranga José ◽  
Lothar Stramma ◽  
Sunke Schmidtko ◽  
Andreas Oschlies
Keyword(s):  
El Niño ◽  
Oxygen Supply ◽  
El Nino ◽  
La Niña ◽  
Vertical Extent ◽  
La Nina ◽  
Minimum Zone ◽  
In Situ Observations ◽  
Oxygen Minimum

Abstract. The El Niño Southern Oscillation (ENSO) with its warm (El Niño) and cold (La Niña) phase has strong impacts on marine ecosystems off Peru. This influence extends from changes in nutrient availability to productivity and oxygen levels. While several studies have demonstrated the influence of ENSO events on biological productivity, less is known about their impact on oxygen concentrations. In situ observations along the Peruvian and Chilean coast have shown a strong water column oxygenation during the 1997/1998 strong El Niño event. These observations suggest a deepening of the oxygen minimum zone (OMZ) along the continental shelf. However, due to reduced spatial coverage of the existing in situ observations, no studies have yet demonstrated the OMZ response to El Niño events in the whole Eastern Tropical South Pacific (ETSP). Furthermore, most studies have focused on El Niño events. Much less attention was given to the oxygen dynamics under La Niña influence. Here, we provide a comprehensive analysis of the ENSO influence on OMZ dynamics. Interannual variability of the OMZ during the period 1990–2010 is derived from a regional coupled physical-biogeochemical model forced with realistic atmospheric and lateral boundary conditions. Our results show a reduction of the vertical extent and a deepening of suboxic waters (SW) during the El Niño phase. During the La Niña phase, there is a vertical expansion of SW. These fluctuations in OMZ extent are due to changes in oxygen supply into its core depth mainly from lateral margins. During the El Niño phase, the enhanced lateral oxygen supply from the subtropics is the main reason for the reduction of SW in both coastal and offshore regions. During the La Niña phase, the oxygenated subtropical waters are blocked by the poleward transport along the southern margin of the OMZ. Consequently, oxygen concentrations within the OMZ are reduced and suboxic conditions expand during La Niña. The detailed analysis of transport pathways presented here provides new insights into how ENSO variability affects the oxygen-sensitive marine biogeochemistry of the ETSP.

scholarly journals Short-term fate of phytodetritus in sediments across the Arabian Sea Oxygen Minimum Zone

2008 ◽  
Vol 5 (1) ◽  
pp. 43-53 ◽  
Author(s):  
J. H. Andersson ◽  
C. Woulds ◽  
M. Schwartz ◽  
G. L. Cowie ◽  
L. A. Levin ◽  
...  
Keyword(s):  
Arabian Sea ◽  
Inorganic Carbon ◽  
Surface Sediments ◽  
Dissolved Inorganic Carbon ◽  
Oxygen Minimum Zone ◽  
Short Term ◽  
Minimum Zone ◽  
Algal Material ◽  
Oxygen Minimum

Abstract. The short-term fate of phytodetritus was investigated across the Pakistan margin of the Arabian Sea at water depths ranging from 140 to 1850 m, encompassing the oxygen minimum zone (~100–1100 m). Phytodetritus sedimentation events were simulated by adding ~44 mmol 13C-labelled algal material per m2 to surface sediments in retrieved cores. Cores were incubated in the dark, at in situ temperature and oxygen concentrations. Overlying waters were sampled periodically, and cores were recovered and sampled (for organisms and sediments) after durations of two and five days. The labelled carbon was subsequently traced into bacterial lipids, foraminiferan and macrofaunal biomass, and dissolved organic and inorganic pools. The majority of the label (20 to 100%) was in most cases left unprocessed in the sediment at the surface. The largest pool of processed carbon was found to be respiration (0 to 25% of added carbon), recovered as dissolved inorganic carbon. Both temperature and oxygen were found to influence the rate of respiration. Macrofaunal influence was most pronounced at the lower part of the oxygen minimum zone where it contributed 11% to the processing of phytodetritus.

Deglacial 14C reservoir ages of surface waters at the northern boundary of Peruvian coastal upwelling

2020 ◽  
Author(s):  
Nicolaas Glock ◽  
Michael Sarnthein ◽  
Kristin Doering ◽  
Gesine Mollenhauer ◽  
Renato Salvatteci
Keyword(s):  
Coastal Upwelling ◽  
Trade Wind ◽  
Small Scale ◽  
Age Difference ◽  
Northern Boundary ◽  
Neogloboquadrina Dutertrei ◽  
Minimum Zone ◽  
Age Model ◽  
The Difference ◽  
Oxygen Minimum

&lt;p&gt;To constrain the accurate age of a marine sediment record, the radiocarbon (&lt;sup&gt;14&lt;/sup&gt;C) ages need to be corrected for short-term and small-scale changes in planktic &lt;sup&gt;14&lt;/sup&gt;C reservoir ages (R&lt;sub&gt;plank&lt;/sub&gt;). Nevertheless, accurate records of past changes in R&lt;sub&gt;plank&lt;/sub&gt; are scarce. Here we present a high-resolution record of deglacial &lt;sup&gt;14&lt;/sup&gt;C ages measured on &lt;em&gt;Globigerina bulloides&lt;/em&gt; in sediment core M77/2-59-1 from the northern boundary (~4&amp;#176;S, 997 m) of the Peruvian upwelling zone. The fine structure of jumps and plateau boundaries in the &lt;sup&gt;14&lt;/sup&gt;C record were tuned to synchronous, thus global structures in the atmospheric &lt;sup&gt;14&lt;/sup&gt;C record of Lake Suigetsu (Bronk Ramsey et al., 2012) and used as tie points for an age model with semi-millennial resolution, moreover to reconstruct deglacial changes in R&lt;sub&gt;plank &lt;/sub&gt;from 17 to 11 cal. ka. In our record, R&lt;sub&gt;plank&lt;/sub&gt; drops from 1250 &lt;sup&gt;14&lt;/sup&gt;C yr prior to 14 cal. ka to ~600 &amp;#8211; 450 &lt;sup&gt;14&lt;/sup&gt;C yr until the plateau named Top of Younger Dryas. The drop suggests a major decrease in coastal upwelling, possibly the result of a southward (poleward) expansion of the Intertropical Convergence Zone and related shift in the southeastern trade wind belt during the B&amp;#248;lling-Aller&amp;#248;d. Subsequent to 14 cal. ka our R&lt;sub&gt;plank &lt;/sub&gt;values are roughly similar to values obtained for thermocline waters near the equator from the age difference between &lt;sup&gt;14&lt;/sup&gt;C ages of wood chunks and &lt;sup&gt;14&lt;/sup&gt;C of &lt;em&gt;G. ruber&lt;/em&gt; (Zhao &amp; Keigwin, 2018). Prior to 14 cal. ka our R&lt;sub&gt;plank &lt;/sub&gt;are ~800 &lt;sup&gt;14&lt;/sup&gt;C yr higher, which corroborates the presumed latitudinal shift of coastal upwelling. Our &lt;sup&gt;14&lt;/sup&gt;C ages measured on G. bulloides differ in part from paired &lt;sup&gt;14&lt;/sup&gt;C ages of &lt;em&gt;Neogloboquadrina dutertrei&lt;/em&gt;, indicating their habitat in different water masses prior to 14 cal. ka, in support of the upwelling affinity of &lt;em&gt;G. bulloides&lt;/em&gt;. In addition, we used our R&lt;sub&gt;plank&lt;/sub&gt; values to accurately derive past ventilation ages of intermediate waters near 1000 m depth based on the difference of paired benthic and planktic &lt;sup&gt;14&lt;/sup&gt;C ages, which is important to constrain centennial to millennial scale changes in circulation influencing the extent of the Peruvian oxygen minimum zone.&lt;/p&gt;&lt;p&gt;References:&lt;/p&gt;&lt;p&gt;Bronk Ramsey, C., et al., Science, 338, 370&amp;#8211;374, 2012.&lt;/p&gt;&lt;p&gt;Zhao &amp; Keigwin, Nature communications, 9, 3077, 2018.&lt;/p&gt;

Acoustic detection of mesopelagic fishes in scattering layers of the Balearic Sea (western Mediterranean)

2014 ◽  
Vol 71 (8) ◽  
pp. 1186-1197 ◽  
Author(s):  
Marian Peña ◽  
M. Pilar Olivar ◽  
Rosa Balbín ◽  
Jose Luis López-Jurado ◽  
Magdalena Iglesias ◽  
...  
Keyword(s):  
Western Mediterranean ◽  
Thermocline Depth ◽  
Late Autumn ◽  
Balearic Sea ◽  
Acoustic Methods ◽  
Minimum Zone ◽  
And Migration ◽  
Gas Bearing ◽  
The Vertical Distribution ◽  
Oxygen Minimum

The distributions of micronekton layers in the Balearic Sea (western Mediterranean) were investigated by acoustic methods. Two multidisciplinary surveys were carried out in late autumn 2009 and summer 2010, recording acoustic, biological, and hydrographic data. We described acoustic layers, migratory behavior, sampled species, and water masses processes. Acoustic modeling of gas-bearing organisms was employed to explain differences between acoustic estimates and sampled abundances. The influence of environmental variables on the vertical distribution and migration pattern of these organisms was analyzed. The thermocline depth was related to the preferred depth for migrating myctophids, while nonmigrant species dwelled in the oxygen minimum zone of the water column both in late autumn and summer periods.

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