| Zonas Costeras | 2021 | Vargas, Cristian A.; Cantarero, Sebastian I.; Sepúlveda, Julio; Galán, Alexander; De Pol-Holz, Ricardo; Walker, Brett; Schneider, Wolfgang; Farías, Laura; D’Ottone, Marcela Cornejo; Walker, Jennifer; Xu, Xiaomei; Salisbury, Joe | A source of isotopically light organic carbon in a low-pH anoxic marine zone | Nature Communications | | 10.1038/s41467-021-21871-4 | 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, A T , DIC and p CO 2 ) 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. | http://www.nature.com/articles/s41467-021-21871-4 | 1604 | 12.0 | Thomson Reuters ISI | carbon, carbonic acid, nitrogen, organic carbon, oxygen, sulfur, water, anoxic conditions, carbon fixation, carbonate system, denitrification, isotopic fractionation, organic carbon, particulate organic carbon, stable isotope, alkalinity, anaerobic ammonium oxidation, article, carbon cycling, carbon dioxide tension, carbon fixation, denitrification, fractionation, heterotrophy, inorganic nutrient, light, microbial community, ph, salinity, temperature, chile |
| Zonas Costeras; Agua y Extremos | 2021 | Carrasco, Jorge F.; Bozkurt, Deniz; Cordero, Raul R. | A review of the observed air temperature in the Antarctic Peninsula. Did the warming trend come back after the early 21st hiatus? | Polar Science | | 10.1016/j.polar.2021.100653 | Recent changes in the near-surface air temperature (nSAT) in the Antarctic Peninsula (AP) suggests that the absence of 21st century warming on Antarctic Peninsula may be coming to end. To examine this, the long-term annual and seasonal variability of the nSAT at eight Antarctic stations located in the AP are analyzed using available data from the SCAR Reader database, complemented with data from the Chilean Weather Service (Frei and O’Higgins). An exponential lter was applied to the original annual and seasonal mean series to obtain a decadal-like variation of the nSAT. A stacked and the standardized anomaly of the nSAT record was constructed to examine the average regional behavior in the AP. Cumulative sum (CUSUM) and changepoint analysis were applied through the stacked nSAT series to highlight signi cant changes caused by variation in weather and climate. The CUSUM and bootstrapping analysis revealed two statistically signi cant breaking points during the 1978–2020 period. The rst one occurred in the late nineties ending a warming period and making the beginning of a cooling period; the second one may have taken place in the mid-2010s and could mark the end of the warming pause. These trends appear to be consistent with the changes observed in the large-scale climate modes (i.e., the Antarctic Annular Mode – AAO). | https://linkinghub.elsevier.com/retrieve/pii/S1873965221000189 | 100653 | | Thomson Reuters ISI | air temperature, antarctic peninsula, change point, reader database, warming and cooling trends |
| Zonas Costeras; Agua y Extremos | 2021 | Bozkurt, Deniz; Bromwich, David H.; Carrasco, Jorge; Rondanelli, Roberto | Temperature and precipitation projections for the Antarctic Peninsula over the next two decades: contrasting global and regional climate model simulations | Climate Dynamics | | 10.1007/s00382-021-05667-2 | This study presents near future (2020–2044) temperature and precipitation changes over the Antarctic Peninsula under the high-emission scenario (RCP8.5). We make use of historical and projected simulations from 19 global climate models (GCMs) participating in Coupled Model Intercomparison Project phase 5 (CMIP5). We compare and contrast GCMs projections with two groups of regional climate model simulations (RCMs): (1) high resolution (15-km) simulations performed with Polar-WRF model forced with bias-corrected NCAR-CESM1 (NC-CORR) over the Antarctic Peninsula, (2) medium resolution (50-km) simulations of KNMI-RACMO21P forced with EC-EARTH (EC) obtained from the CORDEX-Antarctica. A further comparison of historical simulations (1981–2005) with respect to ERA5 reanalysis is also included for circulation patterns and near-surface temperature climatology. In general, both RCM boundary conditions represent well the main circulation patterns of the historical period. Nonetheless, there are important differences in projections such as a notable deepening and weakening of the Amundsen Sea Low in EC and NC-CORR, respectively. Mean annual near-surface temperatures are projected to increase by about 0.5–1.5 ∘C across the entire peninsula. Temperature increase is more substantial in autumn and winter (∼ 2 ∘C). Following opposite circulation pattern changes, both EC and NC-CORR exhibit different warming rates, indicating a possible continuation of natural decadal variability. Although generally showing similar temperature changes, RCM projections show less warming and a smaller increase in melt days in the Larsen Ice Shelf compared to their respective driving fields. Regarding precipitation, there is a broad agreement among the simulations, indicating an increase in mean annual precipitation (∼ 5 to 10%). However, RCMs show some notable differences over the Larsen Ice Shelf where total precipitation decreases (for RACMO) and shows a small increase in rain frequency. We conclude that it seems still difficult to get consistent projections from GCMs for the Antarctic Peninsula as depicted in both RCM boundary conditions. In addition, dominant and common changes from the boundary conditions are largely evident in the RCM simulations. We argue that added value of RCM projections is driven by processes shaped by finer local details and different physics schemes that are introduced by RCMs, particularly over the Larsen Ice Shelf. | http://link.springer.com/10.1007/s00382-021-05667-2 | | | Thomson Reuters ISI | air temperature, climate change, climate modeling, cmip, downscaling, extreme event, global climate, precipitation assessment, regional climate, antarctic peninsula, antarctica, larsen ice shelf, west antarctica |
| Zonas Costeras | 2021 | Alcamán-Arias, María Estrella; Fuentes-Alburquenque, Sebastián; Vergara-Barros, Pablo; Cifuentes-Anticevic, Jerónimo; Verdugo, Josefa; Polz, Martin; Farías, Laura; Pedrós-Alió, Carlos; Díez, Beatriz | Coastal Bacterial Community Response to Glacier Melting in the Western Antarctic Peninsula | Microorganisms | | 10.3390/microorganisms9010088 | Current warming in the Western Antarctic Peninsula (WAP) has multiple effects on the marine ecosystem, modifying the trophic web and the nutrient regime. In this study, the effect of decreased surface salinity on the marine microbial community as a consequence of freshening from nearby glaciers was investigated in Chile Bay, Greenwich Island, WAP. In the summer of 2016, samples were collected from glacier ice and transects along the bay for 16S rRNA gene sequencing, while in situ dilution experiments were conducted and analyzed using 16S rRNA gene sequencing and metatranscriptomic analysis. The results reveal that certain common seawater genera, such as Polaribacter, Pseudoalteromonas and HTCC2207, responded positively to decreased salinity in both the bay transect and experiments. The relative abundance of these bacteria slightly decreased, but their functional activity was maintained and increased the over time in the dilution experiments. However, while ice bacteria, such as Flavobacterium and Polaromonas, tolerated the increased salinity after mixing with seawater, their gene expression decreased considerably. We suggest that these bacterial taxa could be defined as sentinels of freshening events in the Antarctic coastal system. Furthermore, these results suggest that a significant portion of the microbial community is resilient and can adapt to disturbances, such as freshening due to the warming effect of climate change in Antarctica. | https://www.mdpi.com/2076-2607/9/1/88 | 88 | 9.0 | Thomson Reuters ISI | bacterial microbial community, coastal antarctic zone, glacial melting |
| Zonas Costeras; Agua y Extremos | 2021 | Aguirre, Catalina; Flores-Aqueveque, Valentina; Vilches, Pablo; Vásquez, Alicia; Rutllant, José A.; Garreaud, René | Recent Changes in the Low-Level Jet along the Subtropical West Coast of South America | Atmosphere | | 10.3390/atmos12040465 | Surface winds along the subtropical west coast of South America are characterized by the quasi-weekly occurrences of low-level jet events. These short lived but intense wind events impact the coastal ocean environment. Hence, identifying long-term trends in the coastal low-level jet (CLLJ) is essential for understanding changes in marine ecosystems. Here we use ERA5 reanalysis (1979–2019) and an objective algorithm to track anticyclones to investigate recent changes in CLLJ events off central Chile (25–43 °S). Results present evidence that the number of days with intense wind (≥10 ms−1), and the number and duration of CLLJ events have significantly changed off central Chile in recent decades. There is an increase in the number of CLLJ events in the whole study area during winter (June-July-August; JJA), while during summer (December–January–February; DJF) a decrease is observed at lower latitudes (29–34 °S), and an increase is found at the southern boundary of the Humboldt system. We suggest that changes in the central pressures and frequency of extratropical, migratory anticyclones that reach the coast of South America, which force CLLJs, have played an important role in the recent CLLJ changes observed in this region. | https://www.mdpi.com/2073-4433/12/4/465 | 465 | 12.0 | Thomson Reuters ISI | atmospheric pressure, tropics, central chile, coastal ocean environment, extratropical, long-term trend, low level jet, south america, surface winds, wind events, ecosystems, algorithm, anticyclone, climate modeling, coastal zone, jet, long-term change, surface wind, upwelling, chile |
| Zonas Costeras | 2021 | Baldrich, Ángela M.; Pérez-Santos, Iván; Álvarez, Gonzalo; Reguera, Beatriz; Fernández-Pena, Concepción; Rodríguez-Villegas, Camilo; Araya, Michael; Álvarez, Francisco; Barrera, Facundo; Karasiewicz, Stéphane; Díaz, Patricio A. | Niche differentiation of Dinophysis acuta and D. acuminata in a stratified fjord | Harmful Algae | | 10.1016/j.hal.2021.102010 | Dinophysis acuta and D. acuminata are associated with lipophilic toxins in Southern Chile. Blooms of the two species coincided during summer 2019 in a highly stratified fjord system (Puyuhuapi, Chilean Patagonia). High vertical resolution measurements of physical parameters were carried out during 48 h sampling to i) explore physiological status (e.g., division rates, toxin content) and ii) illustrate the fine scale distribution of D. acuta and D. acuminata populations with a focus on water column structure and co-occurring plastid-bearing ciliates. The species-specific resources and regulators defining the realized niches (sensu Hutchinson) of the two species were identified. Differences in vertical distribution, daily vertical migration and in situ division rates (with record values, 0.76 d−1, in D. acuta), in response to the environmental conditions and potential prey availability, revealed their niche differences. The Outlying Mean Index (OMI) analysis showed that the realized niche of D. acuta (cell maximum 7 × 103 cells L−1 within the pycnocline) was characterized by sub-surface estuarine waters (salinity 23 – 25), lower values of turbulence and PAR, and a narrow niche breath. In contrast, the realized niche of D. acuminata (cell maximum 6.8 × 103 cells L−1 just above the pycnocline) was characterized by fresher (salinity 17 – 20) outflowing surface waters, with higher turbulence and light intensity and a wider niche breadth. Results from OMI and PERMANOVA analyses of co-occurring microplanktonic ciliates were compatible with the hypothesis of species such as those from genera Pseudotontonia and Strombidium constituting an alternative ciliate prey to Mesodinium. The D. acuta cell maximum was associated with DSP (OA and DTX-1) toxins and pectenotoxins; that of D. acuminata only with pectenotoxins. Results presented here contribute to a better understanding of the environmental drivers of species-specific blooms of Dinophysis and management of their distinct effects in Southern Chile. | https://linkinghub.elsevier.com/retrieve/pii/S1568988321000378 | 102010 | 103.0 | Thomson Reuters ISI | cell differentiation, chile, ciliate, dinoflagellate, estuary, cell differentiation, chile, ciliophora, dinoflagellida, estuaries |
| Zonas Costeras | 2021 | Rodríguez-Villegas, Camilo; Lee, Matthew R.; Salgado, Pablo; Figueroa, Rosa I.; Baldrich, Ángela; Pérez-Santos, Iván; Tomasetti, Stephen J.; Niklitschek, Edwin; Díaz, Manuel; Álvarez, Gonzalo; Marín, Sandra L.; Seguel, Miriam; Farías, Laura; Díaz, Patricio A. | Drivers of dinoflagellate benthic cyst assemblages in the NW Patagonian Fjords System and its adjacent oceanic shelf, with a focus on harmful species | Science of The Total Environment | | 10.1016/j.scitotenv.2021.147378 | In recent decades, the alteration of coastal food webs (via aquaculture, fishing, and leisure activities), nutrient loading, and an expansion of monitoring programs have prompted an apparent worldwide rise in Harmful Algae Blooms (HABs). Over this time, a parallel increase in HABs has also been observed in the Chilean southern austral region (Patagonia fjords). HAB species like Alexandrium catenella—responsible for Paralytic Shellfish Poisoning (PSP)—are of great public concern due to their negative socioeconomic impacts and significant northward geographical range expansion. Many toxic dinoflagellate species (like A. catenella) produce benthic resting cysts, yet a holistic understanding of the physical-chemical and biological conditions influencing the distributions of cysts in this region is lacking. In this study, we measured a combination of hydrographic (temperature, salinity, and dissolved oxygen) and sediment physical-chemical properties (temperature, pH and redox potential), in addition to meiofaunal abundances –as sediment bioturbators and potential cyst predators– to determine the factors influencing dinoflagellate cyst distribution, with emphasis on A. catenella in and around a “hotspot” area of southern Chile. An analysis of similarities (ANOSIM) test revealed significant differences (p < 0.011) in cyst assemblages between the fjords and oceanic environments. Permutational Analysis of Variance (PERMANOVA) showed significant effects of sediment temperature and silt proportion in explaining differences in the cyst assemblages. A generalized linear model (GLM) indicated that sediment temperature, silt/sand, anoxic conditions, and low abundances of Harpacticoida —a meiofauna herbivore group and potential bioturbator— are associated with the higher resting cyst abundances of the harmful species A. catenella. The implications for A. catenella resting cysts dynamics are discussed, highlighting physical-chemical and biological interactions and their potential for PSP outbreak initiation. | https://linkinghub.elsevier.com/retrieve/pii/S0048969721024499 | 147378 | 785.0 | Thomson Reuters ISI | dissolved oxygen, expansion, leisure, ph, sediments, silt, alexandrium catenellum, algae blooms, chemical and biologicals, chilean patagonium, dinoflagellate resting cyst, harmful algae, meiofauna, paralytic shellfish poisoning, redox potentials, redoxpotential, redox reactions, ammonia, nitrite, river water, algal bloom, benthic foraminifera, dinoflagellate, meiofauna, physicochemical property, redox conditions, species diversity, species richness, alexandrium catenella, analysis of variance, article, dinoflagellate, harmful organism, hydrography, meiofauna, nonhuman, paralytic shellfish poisoning, ph, physical chemistry, population abundance, priority journal, salinity, sea, sea surface temperature, sediment, species composition, species distribution, chile, patagonia, alexandrium, alexandrium catenella, catenella, dinophyceae, harpacticoida |
| Zonas Costeras | 2021 | Farías, L.; Tenorio, S.; Sanzana, K.; Faundez, J. | Temporal methane variability in the water column of an area of seasonal coastal upwelling: A study based on a 12 year time series | Progress in Oceanography | | 10.1016/j.pocean.2021.102589 | Temporal distribution of dissolved CH4 was analysed in a zone of strong seasonal coastal upwelling off central Chile (36.5°S,73°W). Observations were taken from a twelve-year time series that included monthly sampling of the water at eight depths. CH4 concentration fluctuated between 1.75 and 100.9 nmol L-1 (or 67.11% and 3965% of saturation), with the highest levels at bottom waters, which increase as upwelling evolved. Three kind of CH4 profiles were identified; a classical diffusion–advection distribution, with bottom/surface CH4 concentration ratio > 2, was predominantly observed in ~ 54% of the all profiles and attributed to high CH4 production in the sediments during coastal upwelling season (austral spring-summer); a period of higher biological productivity, as well as in hypoxic/anoxic condition. In contrast, relatively homogeneous profiles (CH4 level ratio between bottom and surface depth < 2) was observed about ~ 46% of all profiles during periods of extreme vertical mixing (such as winter storms). Furthermore, irregular CH4 profile with superficial peaks occurring between the surface and 15–30 m depth was likely observed. These peaks indicated that local production rates exceed turbulent mixing rates, suggesting a rapid CH4 cycling due to microbial processes on the surface. Despite the fact that strong seasonality was observed in most oceanographic variables, according to favourable and non-favourable upwelling periods, only a weak seasonality was observed in CH4 content and its air-sea flux, the latter ranged from 1.27 to 47.02 µmol m−2 d-1 (mean ± SD: 10.94 ± 7.48). The annual weighted mean CH4 effluxes during upwelling (64%) and non-upwelling (36%) periods fluctuated from 1.66 to 6.22 mmol m−2 (mean ± SD: 3.40 ± 1.43), highlighting the importance of the continental shelf under the influence of coastal upwelling as a significant CH4 source toward the atmosphere. | https://linkinghub.elsevier.com/retrieve/pii/S0079661121000768 | 102589 | 195.0 | Thomson Reuters ISI | mixing, storms, time series, biological productivity, coastal upwelling, concentration ratio, continental shelves, local production, microbial process, temporal distribution, turbulent mixing, coastal engineering, bottom water, continental shelf, methane, microbial activity, pollutant source, seasonality, temporal variation, time series, upwelling, water column, chile |
| Zonas Costeras | 2021 | De La Fuente, María José; De la Iglesia, Rodrigo; Farias, Laura; Daims, Holger; Lukumbuzya, Michael; Vargas, Ignacio T. | Electrochemical enrichment of marine denitrifying bacteria to enhance nitrate metabolization in seawater | Journal of Environmental Chemical Engineering | | 10.1016/j.jece.2021.105604 | High concentrations of nitrate from industrial discharges to coastal marine environments are a matter of concern owing to their ecological consequences. In the last years, Bioelectrochemical Denitrification Systems (BEDS) have emerged as a promising nitrate removal technology. However, they still have limitations, such as the enrichment strategy for specific microbial communities in the electrodes under natural conditions. In this study, three-electrode electrochemical cells were used to test microbial enrichment from natural seawater by applying three reported potentials associated with the dissimilatory denitrification process (−130, −260, and −570 mV vs. Ag/AgCl). The microbial community analysis showed that by applying −260 mV (vs. Ag/AgCl) to the working electrode, it was possible to significantly enrich denitrifying microorganisms, specifically Marinobacter, in comparison with the control. Furthermore, −260 mV (vs. Ag/AgCl) led to a significantly higher nitrate removal than other conditions, which, combined with cyclic voltammetry analysis, suggested that the polarized electrodes worked as external electron donors for nitrate reduction. Hence, this work demonstrates for the first time that it is possible to enrich marine denitrifying microorganisms by applying an overpotential of −260 mV (vs. Ag/AgCl) without the need for a culture medium, the addition of an exogenous electron donor (i.e., organic matter) or a previously enriched inoculum. | https://linkinghub.elsevier.com/retrieve/pii/S2213343721005819 | 105604 | 9.0 | Thomson Reuters ISI | cyclic voltammetry, denitrification, ecology, electric discharges, electrochemical electrodes, nitrates, seawater, ag/agcl, bioelectrochemical denitrification system, denitrifying bacteria, denitrifying microorganisms, electrochemicals, electron donors, industrial discharges, metabolization, microbial enrichment, nitrates removal, bacteria |
| Zonas Costeras; Agua y Extremos | 2021 | Demortier, Alan; Bozkurt, Deniz; Jacques-Coper, Martín | Identifying key driving mechanisms of heat waves in central Chile | Climate Dynamics | | 10.1007/s00382-021-05810-z | This study explores the main drivers of heat wave (HW) events in central Chile using state-of-the-art reanalysis data (ERA5) and observations during the extended austral summer season (November to March) for the period 1979–2018. Frequency and intensity aspects of the HW events are considered using the total number of the HW events per season and the amplitude. We first contrast ERA5 with several surface meteorological stations in central Chile to evaluate its ability to capture daily maximum temperature variability and the HW events. We then use synoptic- and large-scale fields and teleconnection patterns to address the most favorable conditions of the HW events from a climatological perspective as well as from the extreme January 2017 HW event that swept central Chile with temperature records and wildfires. ERA5 tends to capture temperature extremes and the HW events at the inland stations; on the contrary, it has difficulties in capturing the maximum temperature variability at the coastal stations, which is plausible given the complex terrain features and confined coastal climate zone (only ∼7% of all grid boxes within central Chile). The composite HW days based on ERA5 reveals a mid-level trough-ridge dipole pattern exhibiting a blocking anticyclone on the surface over a large part of southwest South America. Relatively dry and warm easterly flow appears to accompany the anomalous warming in a large part of central Chile. The temporal evolution of the HW events yields a wave-like propagation pattern and enhancement of trough-ridge pattern along the South Pacific. This meridional dipole pattern is found to be largely associated with the Pacific South American pattern. In addition, the Madden–Julian Oscillation (MJO) appears to be a key component of the HW events in central Chile. In particular, while active MJO phases 2 and 7 promote sub-seasonal patterns that favor the South Pacific dipole mode, synoptic anomalies can superimpose on them and favor the formation of a migrating anticyclone over central-southern Chile and coastal lows over central Chile. Agreeing with the climatological findings, the extreme January 2017 HW analysis suggests that an eastward migratory mid-latitude trough-ridge pattern associated with MJO phase 2 was at work. We highlight that in addition to large- and synoptic-scale features, sub-synoptic processes such as coastal lows can have an important role in shaping the HW events and can lead to amplification of temperature extremes during the HW events. | https://link.springer.com/10.1007/s00382-021-05810-z | | | Thomson Reuters ISI | atmospheric teleconnections, blocking pattern, central chile, heat waves, mjo, temperature extremes |
| Zonas Costeras | 2021 | Farías, L.; Troncoso, M.; Sanzana, K.; Verdugo, J.; Masotti, I. | Spatial Distribution of Dissolved Methane Over Extreme Oceanographic Gradients in the Subtropical Eastern South Pacific (17° to 37°S) | Journal of Geophysical Research: Oceans | | 10.1029/2020JC016925 | Methane (CH4) is one of the most powerful greenhouse gases with the capacity to influence the Earth's radiative budget as well as contribute to atmospheric chemistry. Natural oceanic production makes up to ∼4% of the overall global CH4 emissions, however, there is uncertainty around the accuracy of this value due to a lack of accurate measurements. Such is the case in the Subtropical Eastern South Pacific Ocean (SESP), a region with pronounced chlorophyll-a and oxygen gradients, which in turn affect the microbial CH4 cycling. This study was conducted during spring-summer (2014–2016) in the SESP. The region (∼17°–37°S/71°–110°W) is separated into (i) eutrophic, (ii) mesotrophic, and (iii) oligotrophic areas, according to oceanographic and biogeochemical criteria. The SESP presents high CH4 zonal variability with levels ranging from 0.63 to 33.4 nmol L−1, corresponding to 29% and 1,423% saturation, respectively. High CH4 concentrations (>1,000% saturation) are observed in the narrow eutrophic area subjected to coastal upwelling. These conditions clearly differ to those observed in the extended oligotrophic subtropical gyre (∼100% saturation). Furthermore, CH4 also tends to accumulate in the mesotrophic area (with upto 1,423% saturation), where oceanographic conditions as stratification, mesoscale eddies and island mass effect could trigger the presence of a microbial biomass that may be able to induce CH4 regeneration. The CH4 efflux is estimated to be between 0.13 and 19.1 µmol m−2 d−1 (mean ± SD = 4.72 ± 4.67) and the SESP has an emission rate of ∼87.9 Gg CH4 yr−1. | https://onlinelibrary.wiley.com/doi/10.1029/2020JC016925 | | 126.0 | Thomson Reuters ISI | accuracy assessment, atmospheric chemistry, biogeochemistry, biomass, chlorophyll a, concentration (composition), greenhouse gas, gyre, mesoscale eddy, methane, nutrient cycling, radiative transfer, saturation, spatial distribution, upwelling, pacific ocean, pacific ocean (south) |
| Zonas Costeras | 2021 | Pizarro, Jaime; Vergara, Pablo M.; Cerda, Sergio; Cordero, Raúl R.; Castillo, Ximena; Rowe, Penny M.; Casassa, Gino; Carrasco, Jorge; Damiani, Alessandro; Llanillo, Pedro J.; Lambert, Fabrice; Rondanelli, Roberto; Huneeus, Nicolas; Fernandoy, Francisco; Alfonso, Juan; Neshyba, Steven | Contaminant emissions as indicators of chemical elements in the snow along a latitudinal gradient in southern Andes | Scientific Reports | | 10.1038/s41598-021-93895-1 | Abstract The chemical composition of snow provides insights on atmospheric transport of anthropogenic contaminants at different spatial scales. In this study, we assess how human activities influence the concentration of elements in the Andean mountain snow along a latitudinal transect throughout Chile. The concentration of seven elements (Al, Cu, Fe, Li, Mg, Mn and Zn) was associated to gaseous and particulate contaminants emitted at different spatial scales. Our results indicate carbon monoxide (CO) averaged at 20 km and nitrogen oxide (NOx) at 40 km as the main indicators of the chemical elements analyzed. CO was found to be a significant predictor of most element concentrations while concentrations of Cu, Mn, Mg and Zn were positively associated to emissions of NOx. Emission of 2.5 μm and 10 μm particulate matter averaged at different spatial scales was positively associated to concentration of Li. Finally, the concentration of Zn was positively associated to volatile organic compounds (VOC) averaged at 40 km around sampling sites. The association between air contaminants and chemical composition of snow suggests that regions with intensive anthropogenic pollution face reduced quality of freshwater originated from glacier and snow melting. | http://www.nature.com/articles/s41598-021-93895-1 | 14530 | 11.0 | Thomson Reuters ISI | |
| Zonas Costeras; Agua y Extremos | 2021 | Scheiter, Matthias; Schaefer, Marius; Flández, Eduardo; Bozkurt, Deniz; Greve, Ralf | The 21st-century fate of the Mocho-Choshuenco ice cap in southern Chile | The Cryosphere | | 10.5194/tc-15-3637-2021 | Abstract. Glaciers and ice caps are thinning and retreating along the entire Andes ridge, and drivers of this mass loss vary between the different climate zones. The southern part of the Andes (Wet Andes) has the highest abundance of glaciers in number and size, and a proper understanding of ice dynamics is important to assess their evolution. In this contribution, we apply the ice-sheet model SICOPOLIS (SImulation COde for POLythermal Ice Sheets) to the Mocho-Choshuenco ice cap in the Chilean Lake District (40∘ S, 72∘ W; Wet Andes) to reproduce its current state and to project its evolution until the end of the 21st century under different global warming scenarios. First, we create a model spin-up using observed surface mass balance data on the south-eastern catchment, extrapolating them to the whole ice cap using an aspect-dependent parameterization. This spin-up is able to reproduce the most important present-day glacier features. Based on the spin-up, we then run the model 80 years into the future, forced by projected surface temperature anomalies from different global climate models under different radiative pathway scenarios to obtain estimates of the ice cap's state by the end of the 21st century. The mean projected ice volume losses are 56±16 % (RCP2.6), 81±6 % (RCP4.5), and 97±2 % (RCP8.5) with respect to the ice volume estimated by radio-echo sounding data from 2013. We estimate the uncertainty of our projections based on the spread of the results when forcing with different global climate models and on the uncertainty associated with the variation of the equilibrium line altitude with temperature change. Considering our results, we project a considerable deglaciation of the Chilean Lake District by the end of the 21st century. | https://tc.copernicus.org/articles/15/3637/2021/ | 3637-3654 | 15.0 | Thomson Reuters ISI | climate modeling, deglaciation, equilibrium line, glacier dynamics, ice cap, ice sheet, surface temperature, twenty first century, andes, los rios [chile], mocho-choshuenco, southern volcanic zone |
| Zonas Costeras | 2021 | Alarcón-Schumacher, Tomás; Guajardo-Leiva, Sergio; Martinez-Garcia, Manuel; Díez, Beatriz | Ecogenomics and Adaptation Strategies of Southern Ocean Viral Communities | mSystems | | 10.1128/mSystems.00396-21 | Viruses are the most abundant biologic entities in marine systems and strongly influence the microbial community composition and diversity. However, little is known about viral communities’ adaptation and diversification in the ocean. , ABSTRACT The Southern Ocean (SO) represents up to one-fifth of the total carbon drawdown worldwide. Intense selective pressures (low temperature, high UV radiation, and strong seasonality) and physical isolation characterize the SO, serving as a “natural” laboratory for the study of ecogenomics and unique adaptations of endemic viral populations. Here, we report 2,416 novel viral genomes from the SO, obtained from newly sequenced viral metagenomes in combination with mining of publicly available data sets, which represents a 25% increase in the SO viral genomes reported to date. They comprised 567 viral clusters (defined as approximately genus-level groups), with 186 genera endemic to the SO, demonstrating that the SO viral community is predominantly constituted by a large pool of genetically divergent viral species from widespread viral families. The predicted proteome from SO viruses revealed that several protein clusters related to cold-shock-event responses and quorum-sensing mechanisms involved in the lysogenic-lytic cycle shift decision were under positive selection, which is ultimately important for fine adaptation of viral populations in response to the strong selective pressures of the SO. Finally, changes in the hydrophobicity patterns and amino acid frequencies suggested marked temperature-driven genetic selection of the SO viral proteome. Our data provide valuable insights into how viruses adapt and remain successful in this extreme polar marine environment. IMPORTANCE Viruses are the most abundant biologic entities in marine systems and strongly influence the microbial community composition and diversity. However, little is known about viral communities’ adaptation and diversification in the ocean. In this work, we take advantage of the geographical isolation and the intense selective pressures of the SO, to which viruses are exposed, to identify potential viral adaptations due to positive environmental selection and dispersal limitation. To that end, we recovered more than two thousand novel viral genomes, revealing a high degree of divergence in these SO endemic communities. Furthermore, we describe remarkable viral adaptations in amino acid frequencies and accessory proteins related to cold shock response and quorum sensing that allow them to thrive at lower temperatures. Consequently, our work greatly expands the understanding of the diversification of the viral communities of the SO and their particular adaptations to low temperatures. | https://journals.asm.org/doi/10.1128/mSystems.00396-21 | | | Thomson Reuters ISI | molecular and physiological adaptations, southern ocean, stress adaptation, viral diversity |
| Zonas Costeras | 2021 | Tamayo-Leiva, Javier; Cifuentes-Anticevic, Jerónimo; Aparicio-Rizzo, Pilar; Arroyo, José Ignacio; Masotti, Italo; Díez, Beatriz | Influence of Estuarine Water on the Microbial Community Structure of Patagonian Fjords | Frontiers in Marine Science | | 10.3389/fmars.2021.611981 | Fjords are sensitive areas affected by climate change and can act as a natural laboratory to study microbial ecological processes. The Chilean Patagonian fjords (41–56°S), belonging to the Subantarctic ecosystem (46–60°S), make up one of the world’s largest fjord systems. In this region, Estuarine Water (EW) strongly influences oceanographic conditions, generating sharp gradients of oxygen, salinity and nutrients, the effects of which on the microbial community structure are poorly understood. During the spring of 2017 we studied the ecological patterns (dispersal and oceanographic factors) underlying the microbial community distribution in a linear span of 450 km along the estuarine-influenced Chilean Patagonian fjords. Our results show that widespread microbial dispersion existed along the fjords where bacterioplankton exhibited dependence on the eukaryotic phytoplankton community composition. This dependence was particularly observed under the low chlorophyll- a conditions of the Baker Channel area, in which a significant relationship was revealed between SAR11 Clade III and the eukaryotic families Pyrenomonadaceae (Cryptophyte) and Coccomyxaceae (Chlorophyta). Furthermore, dissolved oxygen and salinity were revealed as the main drivers influencing the surface marine microbial communities in these fjords. A strong salinity gradient resulted in the segregation of the Baker Channel prokaryotic communities from the rest of the Patagonian fjords. Likewise, Microbacteriaceae, Burkholderiaceae and SAR11 Clade III, commonly found in freshwater, were strongly associated with EW conditions in these fjords. The direct effect of EW on the microbial community structure and diversity of the fjords exemplifies the significance that climate change and, in particular, deglaciation have on this marine region and its productivity. | https://www.frontiersin.org/articles/10.3389/fmars.2021.611981/full | 611981 | 8.0 | Thomson Reuters ISI | bacterioplankton, estuarine water, eukaryotic phytoplankton, microbial indicator, patagonian fjords, subantarctic |
| Zonas Costeras | 2021 | Bravo, Claudio; Bozkurt, Deniz; Ross, Andrew N.; Quincey, Duncan J. | Projected increases in surface melt and ice loss for the Northern and Southern Patagonian Icefields | Scientific Reports | | 10.1038/s41598-021-95725-w | Abstract The Northern Patagonian Icefield (NPI) and the Southern Patagonian Icefield (SPI) have increased their ice mass loss in recent decades. In view of the impacts of glacier shrinkage in Patagonia, an assessment of the potential future surface mass balance (SMB) of the icefields is critical. We seek to provide this assessment by modelling the SMB between 1976 and 2050 for both icefields, using regional climate model data (RegCM4.6) and a range of emission scenarios. For the NPI, reductions between 1.5 m w.e. (RCP2.6) and 1.9 m w.e. (RCP8.5) were estimated in the mean SMB during the period 2005–2050 compared to the historical period (1976–2005). For the SPI, the estimated reductions were between 1.1 m w.e. (RCP2.6) and 1.5 m w.e. (RCP8.5). Recently frontal ablation estimates suggest that mean SMB in the SPI is positively biased by 1.5 m w.e., probably due to accumulation overestimation. If it is assumed that frontal ablation rates of the recent past will continue, ice loss and sea-level rise contribution will increase. The trend towards lower SMB is mostly explained by an increase in surface melt. Positive ice loss feedbacks linked to increasing in meltwater availability are expected for calving glaciers. | https://www.nature.com/articles/s41598-021-95725-w | 16847 | 11.0 | Thomson Reuters ISI | article, body weight, climate, glacier, sea level rise |
| Zonas Costeras; Agua y Extremos | 2021 | Aguirre, Catalina; Garreaud, René; Belmar, Lucy; Farías, Laura; Ramajo, Laura; Barrera, Facundo | High-Frequency Variability of the Surface Ocean Properties Off Central Chile During the Upwelling Season | Frontiers in Marine Science | | 10.3389/fmars.2021.702051 | The ocean off south-central Chile is subject to seasonal upwelling whose intensity is mainly controlled by the latitudinal migration of the southeast Pacific subtropical anticyclone. During austral spring and summer, the mean flow is equatorward favoring coastal upwelling, but periods of strong southerly winds are intermixed with periods of relaxed southerlies or weak northerly winds (downwelling favorable). This sub-seasonal, high-frequency variability of the coastal winds results in pronounced changes in oceanographic conditions and air-sea heat and gas exchanges, whose quantitative description has been limited by the lack of in-situ monitoring. In this study, high frequency fluctuations of meteorological, oceanographic and biogeochemical near surface variables were analyzed during two consecutive upwelling seasons (2016–17 and 2017–18) using observations from a coastal buoy located in the continental shelf off south-central Chile (36.4°S, 73°W), ∼10 km off the coast. The radiative-driven diel cycle is noticeable in meteorological variables but less pronounced for oceanographic and biogeochemical variables [ocean temperature, nitrate (NO 3 −), partial pressure of carbon dioxide ( p CO 2 sea ), pH, dissolved oxygen (DO)]. Fluorescence, as a proxy of chlorophyll- a , showed diel variations more controlled by biological processes. In the synoptic scale, 23 active upwelling events (strong southerlies, lasting between 2 and 15 days, 6 days in average) were identified, alternated with periods of relaxed southerlies of shorter duration (4.5 days in average). Upwelling events were related to the development of an atmospheric low-level coastal jet in response to an intense along-shore pressure gradient. Physical and biogeochemical surface seawater properties responded to upwelling favorable wind stress with approximately a 12-h lag. During upwelling events, SST, DO and pH decrease, while NO 3 −, p CO 2 sea , and air-sea fluxes increases. During the relaxed southerly wind periods, opposite tendencies were observed. The fluorescence response to wind variations is complex and diverse, but in many cases there was a reduction in the phytoplankton biomass during the upwelling events followed by higher values during wind relaxations. The sub-seasonal variability of the coastal ocean characterized here is important for biogeochemical and productivity studies. | https://www.frontiersin.org/articles/10.3389/fmars.2021.702051/full | 702051 | 8.0 | Thomson Reuters ISI | air-sea exchanges, biogeochemical properties, coastal buoy observations, coastal upwelling, coastal winds, eastern boundary conditions, sub-seasonal variability |
| Zonas Costeras; Agua y Extremos | 2021 | Sparaventi, Erica; Rodríguez-Romero, Araceli; Barbosa, Andrés; Ramajo, Laura; Tovar-Sánchez, Antonio | Trace elements in Antarctic penguins and the potential role of guano as source of recycled metals in the Southern Ocean | Chemosphere | | 10.1016/j.chemosphere.2021.131423 | Penguins dominate the Antarctic avifauna. As key animals in the Antarctic ecosystem, they are monitored to evaluate the ecological status of this pristine and remote region and specifically, they have been used as effective bioindicators suitable for long-term monitoring of metals in the Antarctic environment. However, studies about the role of this emblematic organism could play in the recycling of trace metals (TMs) in the Antarctic ecosystem are very limited. In this study we evaluate, using the peer review research articles already published and our own findings, the distribution of metals (i.e., Ca, Fe, Al, Na, Zn, Mg, Cu, K, Cd, Mn, Sr, Cr, Ni, Pb, Hg, V, Ba, Co, La, Ag, Rb, Hf, Sc, Au and Cs) and metalloids (As and Sb), measured in different biotic matrices, with emphasis on guano, of the Chinstrap (Pygoscelis antarcticus), Adélie (Pygoscelis adeliae) and Gentoo (Pygoscelis papua) penguins. Regarding bioactive metals, the high concentrations (μg g−1 dry weight) of Cu (2.0 ± 1.4) x 102, Fe (4.1 ± 2.9) x 102, Mn (30 ± 34) and Zn (210 ± 90) reported in the guano from all the penguin species studied including our data, are of the same order of magnitude as those reported for whale feces (μg g−1 dry weight): Cu (2.9 ± 2.4) x 102, Fe (1.5 ± 1.4) x 102, Mn (28 ± 17) and Zn (6.2 ± 4.3) x 102, and one order of magnitude higher than the metal contents in krill (μg g−1 dry weight) of Cu (10.2 ± 5.5), Fe (24 ± 29) and Zn (13.5 ± 1.7). This suggest that penguin's excretion products could be an important source of these essential elements in the surface water, with an estimated annual release on a breeding season for Cu, Fe, Mn, Zn respectively of 28, 56, 4 and 29 tons, for the Chinstrap, Adélie and Gentoo penguins. The results provide evidence on the potential influence of penguins recycling TMs in the surface layer of the water column. | https://linkinghub.elsevier.com/retrieve/pii/S0045653521018956 | 131423 | 285.0 | Thomson Reuters ISI | ecosystems, recycling, surface waters, trace elements, antarctica, dropping, dry weight, ecological status, metal concentrations, orders of magnitude, remote regions, southern ocean, trace metal, traces elements, metals, avifauna, bioindicator, breeding season, concentration (composition), excretion, feces, guano, metalloid, recycling, seabird, trace element, whale, southern ocean, pygoscelis antarcticus, spheniscidae |
| Zonas Costeras | 2021 | Jacques‐Coper, Martín; Veloso‐Aguila, Daniel; Segura, Christian; Valencia, Amanda | Intraseasonal teleconnections leading to heat waves in central Chile | International Journal of Climatology | | 10.1002/joc.7096 | The ability to anticipate meteorological extreme events beyond the synoptic range of ~1 week offers direct applications, for example, to limit their ecological and socioeconomical impacts. This study focuses on precursors of summer (December–February, DJF) warm events, particularly heat waves, in central Chile (CCh), which are typically induced by low-level anticyclonic anomalies located to the south of this region. Considering that such atmospheric configuration can be part of a large-scale wave-train circulation pattern located upstream of CCh, we investigate signals that might provide guidance concerning the genesis of warm events in CCh. For a historical period (DJF 1872–2010) based on the 20th century reanalysis version 2 (20CR), our results present teleconnections that indicate higher probabilities of occurrence of such warm events with respect to expected climatological values. These signals can be monitored at least ~2 weeks in advance. Specifically, we explore the relationship between warm events in CCh and (a) the Madden-Julian Oscillation (MJO) as a tropical source of variability, and (b) an extra-tropical index (ETI), representative of the internal dynamics of the Southern Hemipshere mid-latitudes, presented as an original contribution from this study following a novel approach. Both signals, and apparently their constructive superposition, seem to contribute to the organization of the large-scale circulation anomalies leading ultimately to heat waves in CCh. We confirm these results for recent decades (DJF 1981–2020) using temperature observations and further data sets, namely the NCEP-NCAR Reanalysis (NNR) and the Climate Forecast System Reanalysis versions 1 and 2 (CFSR and CFSv2, respectively). Finally, we describe three recent heat wave events in CCh (DJF 2019–2020) to illustrate the suitability of this conceptualization. | https://onlinelibrary.wiley.com/doi/10.1002/joc.7096 | 4712-4731 | 41.0 | Thomson Reuters ISI | tropics, anticyclonic anomalies, circulation patterns, historical periods, large-scale circulation, madden-julian oscillation, meteorological extremes, provide guidances, temperature observations, climatology, atmospheric circulation, extreme event, heat wave, seasonal variation, teleconnection, temperature effect, weather forecasting, chile |
