10 results on '"Sebastian I. Cantarero"'
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2. Size-Fractionated Contribution of Microbial Biomass to Suspended Organic Matter in the Eastern Tropical South Pacific Oxygen Minimum Zone
- Author
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Sebastian I. Cantarero, Carlos Henríquez-Castillo, Nadia Dildar, Cristian A. Vargas, Peter von Dassow, Marcela Cornejo-D’Ottone, and Julio Sepúlveda
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intact polar lipids ,oxygen minimum zone ,marine biogeochemistry ,biomarker ,microbial biomass ,Science ,General. Including nature conservation, geographical distribution ,QH1-199.5 - Abstract
Cell membrane intact polar lipids (IPLs) are chemotaxonomic biomarkers whose abundances and distributions in water column environments reflect the living biomass of in situ microbial communities, and can be used to determine the relative contribution of distinct functional and phylogenetic groups to water column carbon stocks. The diversity of IPLs in marine environments is, however, vast, while our knowledge of their biological origins remains limited. Here, we study the distribution of IPLs in size-fractionated suspended organic matter from the oxygen minimum zone (OMZ) of the eastern tropical South Pacific (ETSP) off northern Chile. Canonical correspondence analyses of total IPL abundances and water column physiochemistry demonstrate distinct distributions of microbial sources associated with different geochemical regions in the water column (chlorophyll maximum, upper chemocline, lower chemocline, upper OMZ, core OMZ, and mesopelagic region). Furthermore, the distribution of IPLs in free-living (0.3–2.7 μm) and particle-attached (2.7–53 μm) suspended organic matter differs, suggesting distinct biological sources in each size fraction. While some parallels exist, the diversity and distribution of IPLs in the OMZ system of the ETSP off northern Chile exhibited some unique features compared to other OMZ systems; for instance, we observed a significantly lower contribution of betaine lipids from phytoplanktonic sources, possibly reflecting a physiological response to severe N-limitation in this area. The overall IPL abundance in the two size fractions also indicates a dominance of free-living biomass in the OMZ and mesopelagic regions, suggesting that these areas of the water column could provide additional sources of submicrometer-sized organic carbon to deeper waters. This study improves the utility of IPLs as chemotaxonomic biomarkers by providing insight into the contrasting distributions of microbial biomass from different life modes (free-living and particle-attached). Our results suggest that microbial production in low oxygen environments may be more important to total water column carbon stocks than previously thought.
- Published
- 2020
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3. Bacterial and eukaryotic intact polar lipids point to in situ production as a key source of labile organic matter in hadal surface sediment of the Atacama Trench
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Edgart Flores, Sebastian I. Cantarero, Paula Ruiz-Fernández, Nadia Dildar, Matthias Zabel, Osvaldo Ulloa, and Julio Sepúlveda
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Ecology, Evolution, Behavior and Systematics ,Earth-Surface Processes - Abstract
Elevated organic matter (OM) concentrations are found in hadal surface sediments relative to the surrounding abyssal seabed. However, the origin of this biological material remains elusive. Here, we report on the composition and distribution of cellular membrane intact polar lipids (IPLs) extracted from surface sediments around the deepest points of the Atacama Trench and adjacent bathyal margin to assess and constrain the sources of labile OM in the hadal seabed. Multiscale bootstrap resampling of IPLs' structural diversity and abundance indicates distinct lipid signatures in the sediments of the Atacama Trench that are more closely related to those found in bathyal sediments than to those previously reported for the upper ocean water column in the region. Whereas the overall number of unique IPL structures in hadal sediments contributes a small fraction of the total IPL pool, we also report a high contribution of phospholipids with mono- and di-unsaturated fatty acids that are not associated with photoautotrophic sources and that resemble traits of physiological adaptation to high pressure and low temperature. Our results indicate that IPLs in hadal sediments of the Atacama Trench predominantly derive from in situ microbial production and biomass, whereas the export of the most labile lipid component of the OM pool from the euphotic zone and the overlying oxygen minimum zone is neglectable. While other OM sources such as the downslope and/or lateral transport of labile OM cannot be ruled out and remain to be studied, they are likely less important in view of the lability of ester-bond IPLs. Our results contribute to the understanding of the mechanisms that control the delivery of labile OM to this extreme deep-sea ecosystem. Furthermore, they provide insights into some potential physiological adaptation of the in situ microbial community to high pressure and low temperature through lipid remodeling.
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- 2022
4. Phytoplankton response to a warming ocean
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Julio Sepúlveda and Sebastian I. Cantarero
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Multidisciplinary ,Hot Temperature ,Oceans and Seas ,Phytoplankton ,Fisheries ,Fishes ,Animals ,Seawater ,Global Warming ,Nutritive Value - Abstract
The nutritional value of marine algae will decrease in a warmer world
- Published
- 2022
5. Supplementary material to 'Intact polar lipids in the hadal seabed of the Atacama Trench point to lateral sediment transport and in situ production as key sources of labile organic matter'
- Author
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Edgart Flores, Sebastian I. Cantarero, Paula Ruiz-Fernández, Nadia Dildar, Matthias Zabel, Osvaldo Ulloa, and Julio Sepúlveda
- Published
- 2021
6. Intact polar lipids in the hadal seabed of the Atacama Trench point to lateral sediment transport and in situ production as key sources of labile organic matter
- Author
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Matthias Zabel, Paula Ruiz-Fernández, Nadia Dildar, Edgart Flores, Sebastian I. Cantarero, Julio Sepúlveda, and Osvaldo Ulloa
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chemistry.chemical_classification ,Abyssal zone ,chemistry ,Environmental chemistry ,Sediment ,Organic matter ,Photic zone ,Hadal zone ,Oxygen minimum zone ,Seabed ,Bathyal zone - Abstract
Elevated concentrations of organic matter are found in sediments of hadal trenches relative to those found in the abyssal seabed, but the origin of such biological material remains elusive. Here, we report the composition and distribution of cell membrane intact polar lipids (IPLs) in surface sediments around the deepest points of the Atacama Trench and adjacent bathyal depths to assess and constrain the sources of labile organic matter in the hadal seabed. Multiscale bootstrap resampling of IPLs’ structural diversity and abundance indicates distinct lipid signatures in the sediments of the Atacama Trench that are more closely related to those found in bathyal sediments than to those previously reported for the upper ocean water column in the region. While the overall number of unique IPL structures in hadal sediments is limited and they contribute a small fraction of the total IPL pool, they include a high contribution of phospholipids with mono- and di-unsaturated fatty acids that are not associated with photoautotrophic sources. The diversity of labile IPLs in hadal sediments of the Atacama Trench suggests the presence of in situ microbial production and biomass that resembles traits of physiological adaptation to high pressure and low temperature, and/or the transport of labile organic matter from shallower sediment. We argue that the export of the most labile lipid component of the organic matter pool from the euphotic zone and the overlying oxygen minimum zone into the hadal sediments is neglectable. Our results contribute to the understanding of the mechanisms that control the delivery of labile organic matter to this extreme deep-sea ecosystem, whereas they provide insights into some potential physiological adaptation of the in situ microbial community to high pressure and low temperature through lipid remodeling.
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- 2021
7. Soil elemental analysis in a high conservation tropical forest in Singapore
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Robert J. Wasson, Sebastian I. Cantarero, Charlene Teo, Elvagris Segovia Estrada, Alan D. Ziegler, and Canh Tien Trinh Nguyen
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geography ,Environmental Engineering ,geography.geographical_feature_category ,0208 environmental biotechnology ,Drainage basin ,02 engineering and technology ,General Medicine ,010501 environmental sciences ,Management, Monitoring, Policy and Law ,Freshwater swamp forest ,Contamination ,01 natural sciences ,Swamp ,020801 environmental engineering ,Urban forest ,Elemental analysis ,Environmental chemistry ,Soil water ,Environmental science ,Trace metal ,Waste Management and Disposal ,0105 earth and related environmental sciences - Abstract
To understand the distribution of soil elemental concentrations and their potential sources of trace metal contamination in the high-conservation Nee Soon freshwater swamp forest in Singapore, we analyzed samples from 227 surface and 35 subsurface (auger profiles) locations. Our assessment involved distribution maps, principle component analysis, cluster analysis, and correlation analysis of element concentrations determined from a mixed acid digestion and measurement on an ICP-MS. We found a distinct zonation in the distribution of several elements (Ba, Cr, Cu, Fe, Mn, Pb, Sr, Ti, V, and Zn) between the upper and lower catchment that gives an erroneous notion of widespread contamination in the lower catchment. We believe this zonation is natural, likely related to differences in the underlying geology. However, Cu, Pb, and Sb concentrations were greatly enriched by anthropogenic activities on military training lands in the lower catchment, firing ranges in particular. Barium, Sr, and Zn also appear to be enriched in the lower part of the catchment, possibly from anthropogenic activities including military activity and roads. Although soils in the catchment are not highly contaminated, isolated areas with high concentrations of Cu, Pb and Sb may warrant management attention given the sensitive nature of the urban forest, which includes the last remaining fresh water swamp forest in Singapore.
- Published
- 2019
8. A source of isotopically light organic carbon in a low-pH anoxic marine zone
- Author
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Julio Sepúlveda, Cristian A. Vargas, Marcela Cornejo D’Ottone, Xiaomei Xu, Sebastian I. Cantarero, Alexander Galán, Ricardo De Pol-Holz, Jennifer Walker, Brett D. Walker, Wolfgang Schneider, Laura Farías, and Joe Salisbury
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0301 basic medicine ,Denitrification ,010504 meteorology & atmospheric sciences ,Science ,Alkalinity ,General Physics and Astronomy ,Biochemistry ,01 natural sciences ,Article ,General Biochemistry, Genetics and Molecular Biology ,Carbon cycle ,03 medical and health sciences ,chemistry.chemical_compound ,0105 earth and related environmental sciences ,Total organic carbon ,Multidisciplinary ,Stable isotope ratio ,Carbon fixation ,General Chemistry ,Biogeochemistry ,Anoxic waters ,Chemistry ,Ocean sciences ,030104 developmental biology ,chemistry ,Environmental chemistry ,Carbonate ,sense organs - Abstract
Geochemical and stable isotope measurements in the anoxic marine zone (AMZ) off northern Chile during periods of contrasting oceanographic conditions indicate that microbial processes mediating sulfur and nitrogen cycling exert a significant control on the carbonate chemistry (pH, AT, DIC and pCO2) of this region. Here we show that in 2015, a large isotopic fractionation between DIC and POC, a DIC and N deficit in AMZ waters indicate the predominance of in situ dark carbon fixation by sulfur-driven autotrophic denitrification in addition to anammox. In 2018, however, the fractionation between DIC and POC was significantly lower, while the total alkalinity increased in the low-pH AMZ core, suggesting a predominance of heterotrophic processes. An isotope mass-balance model demonstrates that variations in the rates of sulfur- and nitrogen-mediated carbon fixation in AMZ waters contribute ~7–35% of the POC exported to deeper waters. Thus, dark carbon fixation should be included in assessments of future changes in carbon cycling and carbonate chemistry due to AMZ expansion., Anoxic marine zones are expanding and intensifying with climate change. Here the authors show that microbial dark carbon fixation influences the carbonate system and the stable isotope composition in waters off Chile, contributing up to 35% of the organic carbon reaching the mesopelagic region.
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- 2021
9. Simultaneous analysis of Ba and Sr to Ca ratios in scleractinian corals by inductively coupled plasma optical emissions spectrometry
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Nathalie F. Goodkin, Sebastian I. Cantarero, and Jani Tanzil
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Accuracy and precision ,010504 meteorology & atmospheric sciences ,Chemistry ,Coral ,Analytical chemistry ,Ocean Engineering ,010502 geochemistry & geophysics ,Mass spectrometry ,01 natural sciences ,Matrix (chemical analysis) ,Lower cost ,Inductively coupled plasma ,Inductively coupled plasma mass spectrometry ,0105 earth and related environmental sciences - Abstract
Chemical analyses of coral skeletons are useful for reconstructing past ocean conditions. Simultaneous measurements of Ba and Sr to Ca ratios in coral samples have predominantly been achieved by inductively coupled plasma mass spectrometry (ICP-MS). We demonstrate a method that expands the application of the inductively coupled plasma optical emissions spectrometry (ICP-OES) technique to precisely analyze Ba, Sr, and Ca simultaneously. Analytical drift and matrix interferences at a range of Ba/Ca ratios (3–10 μmols/mol) were explored to determine the efficacy of standardized corrections. Minor disparity in drift and matrix interferences between standards of varying Ba/Ca ratios indicate that standardized corrections can be applied. Comparative analysis between ICP-OES and an established ICP-MS technique in a Singapore coral and international coral standard JCp-1 were utilized to validate the proposed ICP-OES technique. ICP-MS and ICP-OES techniques showed a consistent offset, which was correctible with the use of an internal lab standard and resulted in only minor differences between techniques. ICP-OES showed comparable accuracy and precision to the ICP-MS, as evaluated by analysis of JCp-1 which averaged values within one standard deviation of established concentrations (accurate to within 0.38 μmol Ba/mol Ca and 0.014 mmol Sr/mol Ca). We have demonstrated a sufficiently precise and accurate method for simultaneous analysis of Ba and Sr to Ca ratios in coral samples on an ICP-OES system. Expanding the application of ICP-OES in coral geochemical analysis provides a lower cost alternative to ICP-MS, while maintaining a high sample throughput.
- Published
- 2016
10. A clear and present danger: Ladakh's increasing vulnerability to flash floods and debris flows
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Jamie Gillen, Alan D. Ziegler, Pradeep Srivastava, Winston T. L. Chow, Robert J. Wasson, Sebastian I. Cantarero, and Sonam Spalzin
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Hydrology ,021110 strategic, defence & security studies ,geography.geographical_feature_category ,010504 meteorology & atmospheric sciences ,business.industry ,Environmental resource management ,0211 other engineering and technologies ,Vulnerability ,Alluvial fan ,Climate change ,Storm ,02 engineering and technology ,01 natural sciences ,Debris ,Debris flow ,Geography ,Flash flood ,business ,Tourism ,0105 earth and related environmental sciences ,Water Science and Technology - Abstract
This preliminary investigation of the recent spate of deadly flash floods and debris flows in Ladakh (India) over the last decade identifies uncontrolled development in hazardous locations as an important factor contributing to loss of life and property damage in this high mountain desert. The sediments exposed in the channel banks and on the alluvial fans of several mountain streams in the area indicate a long history of flash floods and debris flows resulting from intense storms, which appear to have increased in frequency within the last decade. The signposts of these recurrent hazards are being ignored as a growing economy, which is boosted by a well-established tourism industry, is now driving development onto lands that are susceptible to floods and debris flow hazards. In this science briefing we argue that the increasing vulnerability in Ladakh should be addressed with sound disaster governance strategies that are proactive, rather than reactionary. Copyright © 2016 John Wiley & Sons, Ltd.
- Published
- 2016
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