Research line:

Coastal zone

Considering that Chile’s major cities are in the coastal zone, this research line seeks to determine the impact of climate change on these socio-natural territories.

For the 2024-2025 period, the research line is committed to a comprehensive approach, delving deeper into the physical and biogeochemical coastal processes at various spatiotemporal scales. From a socio-ecological perspective, this approach will focus on understanding the drivers, impacts, risks, and feedback.

Efforts are directed toward understanding the co-variability between coastal upwelling and the oxygen minimum zone in Chile, particularly with hypoxia (lack of oxygen) events. The dynamics of ice melt and its connection with atmospheric processes are also studied, which is crucial for studying the impacts of climate change on the Antarctic ice sheet and sea level rise.

Work is being done on the research and characterization of extreme events, such as harmful algal blooms and marine heat waves, through in situ and remote observations and the use of coupled regional numerical models (atmosphere-ocean waves).

The research line is dedicated to bringing its findings to the local scale, aiming to provide a comprehensive understanding of the impacts, risks, and processes of coastal communities in building resilience. Moreover, it seeks to identify potential coastal climate refugia, offering practical solutions based on current environmental variability, future scenarios, and potential services to protect against future climate risks.

Review the research achievements of this line in our institutional report.







TítuloAutoresLínea de InvestigaciónAñoDOIAbstractRevistaISSNAccesoPáginasVolumenIndexKey Words
A source of isotopically light organic carbon in a low-pH anoxic marine zoneVargas, 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, JoeZonas Costeras2021.010.1038/s41467-021-21871-4Abstract 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.Nature Communications2041-1723 Reuters ISIcarbon, 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
A review of the observed air temperature in the Antarctic Peninsula. Did the warming trend come back after the early 21st hiatus?Carrasco, Jorge F.; Bozkurt, Deniz; Cordero, Raul R.Zonas Costeras; Agua y Extremos2021.010.1016/j.polar.2021.100653Recent 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).Polar Science18739652 Reuters ISIair temperature, antarctic peninsula, change point, reader database, warming and cooling trends
Temperature and precipitation projections for the Antarctic Peninsula over the next two decades: contrasting global and regional climate model simulationsBozkurt, Deniz; Bromwich, David H.; Carrasco, Jorge; Rondanelli, RobertoZonas Costeras; Agua y Extremos2021.010.1007/s00382-021-05667-2This 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.Climate Dynamics0930-7575, 1432-0894 Reuters ISIair temperature, climate change, climate modeling, cmip, downscaling, extreme event, global climate, precipitation assessment, regional climate, antarctic peninsula, antarctica, larsen ice shelf, west antarctica
Coastal Bacterial Community Response to Glacier Melting in the Western Antarctic PeninsulaAlcamán-Arias, María Estrella; Fuentes-Alburquenque, Sebastián; Vergara-Barros, Pablo; Cifuentes-Anticevic, Jerónimo; Verdugo, Josefa; Polz, Martin; Farías, Laura; Pedrós-Alió, Carlos; Díez, BeatrizZonas Costeras2021.010.3390/microorganisms9010088Current 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.Microorganisms2076-2607 Reuters ISIbacterial microbial community, coastal antarctic zone, glacial melting
Recent Changes in the Low-Level Jet along the Subtropical West Coast of South AmericaAguirre, Catalina; Flores-Aqueveque, Valentina; Vilches, Pablo; Vásquez, Alicia; Rutllant, José A.; Garreaud, RenéZonas Costeras; Agua y Extremos2021.010.3390/atmos12040465Surface 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.Atmosphere2073-4433 Reuters ISIatmospheric 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
Niche differentiation of Dinophysis acuta and D. acuminata in a stratified fjordBaldrich, 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.Zonas Costeras2021.010.1016/j.hal.2021.102010Dinophysis 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.Harmful Algae15689883 Reuters ISIcell differentiation, chile, ciliate, dinoflagellate, estuary, cell differentiation, chile, ciliophora, dinoflagellida, estuaries
Drivers of dinoflagellate benthic cyst assemblages in the NW Patagonian Fjords System and its adjacent oceanic shelf, with a focus on harmful speciesRodríguez-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.Zonas Costeras2021.010.1016/j.scitotenv.2021.147378In 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.Science of The Total Environment0048-9697 Reuters ISIdissolved 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
Temporal methane variability in the water column of an area of seasonal coastal upwelling: A study based on a 12 year time seriesFarías, L.; Tenorio, S.; Sanzana, K.; Faundez, J.Zonas Costeras2021.010.1016/j.pocean.2021.102589Temporal 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.Progress in Oceanography0079-6611 Reuters ISImixing, 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
Electrochemical enrichment of marine denitrifying bacteria to enhance nitrate metabolization in seawaterDe La Fuente, María José; De la Iglesia, Rodrigo; Farias, Laura; Daims, Holger; Lukumbuzya, Michael; Vargas, Ignacio T.Zonas Costeras2021.010.1016/j.jece.2021.105604High 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.Journal of Environmental Chemical Engineering2213-3437 Reuters ISIcyclic 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
Identifying key driving mechanisms of heat waves in central ChileDemortier, Alan; Bozkurt, Deniz; Jacques-Coper, MartínZonas Costeras; Agua y Extremos2021.010.1007/s00382-021-05810-zThis 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.Climate Dynamics0930-7575, 1432-0894 Reuters ISIatmospheric teleconnections, blocking pattern, central chile, heat waves, mjo, temperature extremes
Spatial Distribution of Dissolved Methane Over Extreme Oceanographic Gradients in the Subtropical Eastern South Pacific (17° to 37°S)Farías, L.; Troncoso, M.; Sanzana, K.; Verdugo, J.; Masotti, I.Zonas Costeras2021.010.1029/2020JC016925Methane (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.Journal of Geophysical Research: Oceans2169-9275, 2169-9291 Reuters ISIaccuracy 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)
Contaminant emissions as indicators of chemical elements in the snow along a latitudinal gradient in southern AndesPizarro, 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, StevenZonas Costeras2021.010.1038/s41598-021-93895-1Abstract 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.Scientific Reports2045-2322 Reuters ISI
The 21st-century fate of the Mocho-Choshuenco ice cap in southern ChileScheiter, Matthias; Schaefer, Marius; Flández, Eduardo; Bozkurt, Deniz; Greve, RalfZonas Costeras; Agua y Extremos2021.010.5194/tc-15-3637-2021Abstract. 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.The Cryosphere1994-0424 Reuters ISIclimate modeling, deglaciation, equilibrium line, glacier dynamics, ice cap, ice sheet, surface temperature, twenty first century, andes, los rios [chile], mocho-choshuenco, southern volcanic zone
Ecogenomics and Adaptation Strategies of Southern Ocean Viral CommunitiesAlarcón-Schumacher, Tomás; Guajardo-Leiva, Sergio; Martinez-Garcia, Manuel; Díez, BeatrizZonas Costeras2021.010.1128/mSystems.00396-21Viruses 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.mSystems2379-5077 Reuters ISImolecular and physiological adaptations, southern ocean, stress adaptation, viral diversity
Influence of Estuarine Water on the Microbial Community Structure of Patagonian FjordsTamayo-Leiva, Javier; Cifuentes-Anticevic, Jerónimo; Aparicio-Rizzo, Pilar; Arroyo, José Ignacio; Masotti, Italo; Díez, BeatrizZonas Costeras2021.010.3389/fmars.2021.611981Fjords 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.Frontiers in Marine Science2296-7745 Reuters ISIbacterioplankton, estuarine water, eukaryotic phytoplankton, microbial indicator, patagonian fjords, subantarctic
Projected increases in surface melt and ice loss for the Northern and Southern Patagonian IcefieldsBravo, Claudio; Bozkurt, Deniz; Ross, Andrew N.; Quincey, Duncan J.Zonas Costeras2021.010.1038/s41598-021-95725-wAbstract 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.Scientific Reports2045-2322 Reuters ISIarticle, body weight, climate, glacier, sea level rise
High-Frequency Variability of the Surface Ocean Properties Off Central Chile During the Upwelling SeasonAguirre, Catalina; Garreaud, René; Belmar, Lucy; Farías, Laura; Ramajo, Laura; Barrera, FacundoZonas Costeras; Agua y Extremos2021.010.3389/fmars.2021.702051The 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.Frontiers in Marine Science2296-7745 Reuters ISIair-sea exchanges, biogeochemical properties, coastal buoy observations, coastal upwelling, coastal winds, eastern boundary conditions, sub-seasonal variability
Trace elements in Antarctic penguins and the potential role of guano as source of recycled metals in the Southern OceanSparaventi, Erica; Rodríguez-Romero, Araceli; Barbosa, Andrés; Ramajo, Laura; Tovar-Sánchez, AntonioZonas Costeras; Agua y Extremos2021.010.1016/j.chemosphere.2021.131423Penguins 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.Chemosphere00456535 Reuters ISIecosystems, 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
Intraseasonal teleconnections leading to heat waves in central ChileJacques‐Coper, Martín; Veloso‐Aguila, Daniel; Segura, Christian; Valencia, AmandaZonas Costeras2021.010.1002/joc.7096The 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.International Journal of Climatology0899-8418, 1097-0088 Reuters ISItropics, 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
Assessment of ECMWF SEAS5 seasonal forecast performance over South AmericaGubler, S.; Sedlmeier, K.; Bhend, J.; Avalos, G.; Coelho, C. A. S.; Escajadillo, Y.; Jacques-Coper, M.; Martinez, R.; Schwierz, C.; de Skansi, M.; Spirig, Ch.Zonas Costeras2020.010.1175/WAF-D-19-0106.1Seasonal predictions have a great socio-economic potential if they are reliable and skillful. In this study, we assess the prediction performance of SEAS5, version 5 of the seasonal prediction system of the European Centre for Medium-Range Weather Forecasts (ECMWF), over South America against homogenized station data. For temperature, we find highest prediction performances in the tropics during austral summer, where the probability that the predictions correctly discriminate different observed outcomes is 70%. In regions lying to the east of the Andes, the predictions of maximum and minimum temperature still exhibit considerable performance, while further to the south in Chile and Argentina the temperature prediction performance is low. Generally, the prediction performance of minimum temperature is slightly lower than for maximum temperature. The prediction performance of precipitation is generally lower and spatially and temporally more variable than for temperature. The highest prediction performance is observed at the coast and over the highlands of Colombia and Ecuador, over north-eastern part of Brazil, and over an isolated region to the north of Uruguay during DJF. In general, Nino3.4 has a strong influence on both air temperature and precipitation in the regions where ECMWF SEAS5 shows high performance, in some regions through teleconnections (e.g., to the north of Uruguay). However, we show that SEAS5 outperforms a simple empirical prediction based on Nino3.4 in most regions where the prediction performance of the dynamical model is high, thereby supporting the potential benefit of using a dynamical model instead of statistical relationships for predictions at the seasonal scale.Weather and Forecasting0882-8156, 1520-0434 Reuters ISIclimatology, empirical predictions, european centre for medium-range weather forecasts, maximum and minimum temperatures, minimum temperatures, prediction performance, seasonal prediction, statistical relationship, temperature prediction, weather forecasting, air temperature, climate prediction, performance assessment, precipitation (climatology), summer, teleconnection, weather forecasting, argentina, brazil, chile, colombia, ecuador, uruguay
Late Quaternary climatic variability in northern Patagonia, Argentina, based on δ18O of modern and fossil shells of Amiantis purpurata (Bivalvia, Veneridae)Bayer, Sol; Beierlein, Lars; Morán, Gisela A.; Doldán, María S.; Morsan, Enrique M.; Brey, Thomas; Mackensen, Andreas; Farias, Laura; García, Gerardo; Gordillo, SandraZonas Costeras2020.010.1016/j.palaeo.2020.110012Amiantis purpurata is a common warm-temperate water bivalve species distributed from southern Brazil to northern Patagonia, Argentina, which has a rich and well preserved fossil record in the San Matías Gulf (SMG) dating back to the late Quaternary. This study aims to establish A. purpurata shells as a new palaeoarchive of past marine conditions in South America. We compared the stable oxygen and carbon profiles (δ18Oshell; δ13Cshell) of eleven specimens of A. purpurata from different geological times (modern, Late Holocene and interglacial Late Pleistocene), and additionally present in situ oxygen isotope values of seawater within SMG (δ18Owater). Using both sets of information, we calculated and reconstructed palaeowater temperatures for the Late Holocene and compared them to modern water temperatures. Our findings indicate that A. purpurata records past environmental parameters such as water temperatures on a seasonal scale and can therefore be considered a suitable candidate for future palaeoenvironmental reconstructions in Northern Patagonia. This study is the first step towards further stable isotope analyses on fossil A. purpurata shells, which will show whether and if so, to what extent, important global climate events such as the Neoglacial (Early Holocene), the Hypsithermal (Middle Holocene) and the Little Ice Age (Late Holocene) occurred in South America.Palaeogeography, Palaeoclimatology, Palaeoecology00310182 Reuters ISIbivalve, climate variation, fossil record, global climate, hypsithermal, interglacial, little ice age, marine environment, neoglacial, oxygen isotope, pleistocene-holocene boundary, quaternary, shell, type specimen, argentina, atlantic ocean, brazil, san matias gulf, amiantis, bivalvia, veneridae
South Pacific Subtropical High from the late Holocene to the end of the 21st century: insights from climate proxies and general circulation modelsFlores-Aqueveque, Valentina; Rojas, Maisa; Aguirre, Catalina; Arias, Paola A.; González, CharlesZonas Costeras; Gobernanza e Interfaz Ciencia y Política2020.010.5194/cp-16-79-2020Abstract. The South Pacific Subtropical High (SPSH) is a predominant feature of the South American climate. The variability of this high-pressure center induces changes in the intensity of coastal alongshore winds and precipitation, among others, over southwestern South America. In recent decades, strengthening and expansion of the SPSH have been observed and attributed to the current global warming. These changes have led to an intensification of the southerly winds along the coast of northern to central Chile and a decrease in precipitation from central to southern Chile. Motivated by improving our understanding about the regional impacts of climate change in this part of the Southern Hemisphere, we analyzed SPSH changes during the two most extreme climate events of the last millennium, the Little Ice Age (LIA) and the Current Warm Period (CWP: 1970–2000), based on paleoclimate records and CMIP5/PMIP3 model simulations. In order to assess the level of agreement of general circulation models, we also compare them with ERA-Interim reanalysis data for the 1979–2009 period as a complementary analysis. Finally, with the aim of evaluating future SPSH behavior, we include 21st century projections under a Representative Concentration Pathway (RCP8.5) scenario in our analyses. Our results indicate that during the relative warm (cold) period, the SPSH expands (contracts). Together with this change, alongshore winds intensify (weaken) south (north) of ∼35∘ S; also, southern westerly winds become stronger (weaker) and shift southward (northward). Model results generally underestimate reanalysis data. These changes are in good agreement with paleoclimate records, which suggest that these variations could be related to tropical climate dynamics but also to extratropical phenomena. However, although models adequately represent most of the South American climate changes, they fail to represent the Intertropical Convergence Zone–Hadley cell system dynamics, emphasizing the importance of improving tropical system dynamics in simulations for a better understanding of its effects on South America. Climate model projections indicate that changes recently observed will continue during the next decades, highlighting the need to establish effective mitigation and adaptation strategies against their environmental and socioeconomic impacts.Climate of the Past1814-9332 Reuters ISIclimate change, general circulation model, holocene, little ice age, paleoclimate, proxy climate record, twenty first century, chile, pacific ocean, pacific ocean (south), south america
Gene fusion of heterophyletic gamma-globin genes in platyrrhine primatesArroyo, José Ignacio; Nery, Mariana F.Zonas Costeras2018.010.1007/s12041-018-1039-0We performed phylogenetic analyses of HBG genes to assess its origin and interspecific variation among primates. Our analyses showed variation in HBG genes copy number ranging from one to three, some of them pseudogenes. For platyrrhines HBG genes, phylogenetic reconstructions of flanking regions recovered orthologous clades with distinct topologies for 5′ and 3′ flanking regions. The 5′ region originated in the common ancestor of platyrrhines but the 3′ region had an anthropoid origin. We hypothesize that the platyrrhine HBG genes of 5′ and 3′ heterophyletic origins arose from subsequent fusions of the (earlier) platyrrhine 5′ portion and the (later) anthropoid 3′ portion.Journal of Genetics0022-1333, 0973-7731 Reuters ISIhemoglobin gamma chain, animal, biological model, classification, gene duplication, gene fusion, genetic variation, genetics, molecular evolution, phylogeny, primate, pseudogene, animals, evolution, molecular, gamma-globins, gene duplication, gene fusion, genetic variation, models, genetic, phylogeny, primates, pseudogenes
Metagenomic Insights into the Sewage RNA Virosphere of a Large CityGuajardo-Leiva, Sergio; Chnaiderman, Jonás; Gaggero, Aldo; Díez, BeatrizZonas Costeras2020.010.3390/v12091050Sewage-associated viruses can cause several human and animal diseases, such as gastroenteritis, hepatitis, and respiratory infections. Therefore, their detection in wastewater can reflect current infections within the source population. To date, no viral study has been performed using the sewage of any large South American city. In this study, we used viral metagenomics to obtain a single sample snapshot of the RNA virosphere in the wastewater from Santiago de Chile, the seventh largest city in the Americas. Despite the overrepresentation of dsRNA viruses, our results show that Santiago’s sewage RNA virosphere was composed mostly of unknown sequences (88%), while known viral sequences were dominated by viruses that infect bacteria (60%), invertebrates (37%) and humans (2.4%). Interestingly, we discovered three novel genogroups within the Picobirnaviridae family that can fill major gaps in this taxa’s evolutionary history. We also demonstrated the dominance of emerging Rotavirus genotypes, such as G8 and G6, that have displaced other classical genotypes, which is consistent with recent clinical reports. This study supports the usefulness of sewage viral metagenomics for public health surveillance. Moreover, it demonstrates the need to monitor the viral component during the wastewater treatment and recycling process, where this virome can constitute a reservoir of human pathogens.Viruses1999-4915 Reuters ISIprotein e6, rna, rna 16s, rna directed rna polymerase, viral protein, acute gastroenteritis, aedes aegypti, amino acid substitution, animal disease, antibiotic resistance, article, bioinformatics, bromoviridae, caudovirales, chile, cystoviridae, dna extraction, escherichia coli, feces analysis, flocculation, gastroenteritis, genetic variability, genome analysis, genotype, greenhouse effect, health survey, high throughput sequencing, hospitalization, human, human rotavirus, illumina sequencing, intestine flora, metagenome, metagenomics, microbial community, microbial diversity, nonhuman, norovirus, nucleotide sequence, open reading frame, phage therapy, phylogenetic tree, phylogeny, picobirnaviridae, polyacrylamide gel electrophoresis, prevalence, public health, real time polymerase chain reaction, recycling, retroposon, rotavirus, rotavirus c, sequence analysis, sewage, taxonomy, ultracentrifugation, vaccination, viral gastroenteritis, virosphere, virus detection, virus genome, virus particle, wart virus, waste water management, water availability, animal, classification, genetics, invertebrate, metagenome, metagenomics, picobirnavirus, procedures, rna virus, sewage, virology, virus, wastewater, animals, chile, humans, invertebrates, metagenome, metagenomics, picobirnavirus, rna viruses, rotavirus, sewage, viral proteins, viruses, waste water
The Chilean Tornado Outbreak of May 2019: Synoptic, mesoscale, and historical contextsVicencio, José; Rondanelli, Roberto; Campos, Diego; Valenzuela, Raúl; Garreaud, René; Reyes, Alejandra; Padilla, Rodrigo; Abarca, Ricardo; Barahona, Camilo; Delgado, Rodrigo; Nicora, GabrielaZonas Costeras; Agua y Extremos2020.010.1175/BAMS-D-19-0218.1Capsule An unprecedented tornado outbreak occurred in Southern Chile, with at least seven tornadoes reported over a period of 24 hours, causing substantial damage, dozens of injuries, and one fatality.Bulletin of the American Meteorological Society0003-0007, 1520-0477 Reuters ISIpotential energy, storms, anecdotal evidences, convective available potential energies, lightning datum, low-level winds, mid-latitude storms, tornado outbreak, vorticity generation, western south america, tornadoes
Ideas and perspectives: A strategic assessment of methane and nitrous oxide measurements in the marine environmentWilson, Samuel T.; Al-Haj, Alia N.; Bourbonnais, Annie; Frey, Claudia; Fulweiler, Robinson W.; Kessler, John D.; Marchant, Hannah K.; Milucka, Jana; Ray, Nicholas E.; Suntharalingam, Parvadha; Thornton, Brett F.; Upstill-Goddard, Robert C.; Weber, Thomas S.; Arévalo-Martínez, Damian L.; Bange, Hermann W.; Benway, Heather M.; Bianchi, Daniele; Borges, Alberto V.; Chang, Bonnie X.; Crill, Patrick M.; del Valle, Daniela A.; Farías, Laura; Joye, Samantha B.; Kock, Annette; Labidi, Jabrane; Manning, Cara C.; Pohlman, John W.; Rehder, Gregor; Sparrow, Katy J.; Tortell, Philippe D.; Treude, Tina; Valentine, David L.; Ward, Bess B.; Yang, Simon; Yurganov, Leonid N.Zonas Costeras2020.010.5194/bg-17-5809-2020Abstract. In the current era of rapid climate change, accurate characterization of climate-relevant gas dynamics – namely production, consumption, and net emissions – is required for all biomes, especially those ecosystems most susceptible to the impact of change. Marine environments include regions that act as net sources or sinks for numerous climate-active trace gases including methane (CH4) and nitrous oxide (N2O). The temporal and spatial distributions of CH4 and N2O are controlled by the interaction of complex biogeochemical and physical processes. To evaluate and quantify how these mechanisms affect marine CH4 and N2O cycling requires a combination of traditional scientific disciplines including oceanography, microbiology, and numerical modeling. Fundamental to these efforts is ensuring that the datasets produced by independent scientists are comparable and interoperable. Equally critical is transparent communication within the research community about the technical improvements required to increase our collective understanding of marine CH4 and N2O. A workshop sponsored by Ocean Carbon and Biogeochemistry (OCB) was organized to enhance dialogue and collaborations pertaining to marine CH4 and N2O. Here, we summarize the outcomes from the workshop to describe the challenges and opportunities for near-future CH4 and N2O research in the marine environment.Biogeosciences1726-4189 Reuters ISIbiogeochemistry, gas exchange, marine ecosystem, methane, nitrous oxide, numerical model, strategic approach
Low-Cost Ka-Band Cloud Radar System for Distributed Measurements within the Atmospheric Boundary LayerAguirre, Roberto; Toledo, Felipe; Rodríguez, Rafael; Rondanelli, Roberto; Reyes, Nicolas; Díaz, MarcosZonas Costeras2020.010.3390/rs12233965Radars are used to retrieve physical parameters related to clouds and fog. With these measurements, models can be developed for several application fields such as climate, agriculture, aviation, energy, and astronomy. In Chile, coastal fog and low marine stratus intersect the coastal topography, forming a thick fog essential to sustain coastal ecosystems. This phenomenon motivates the development of cloud radars to boost scientific research. In this article, we present the design of a Ka-band cloud radar and the experiments that prove its operation. The radar uses a frequency-modulated continuous-wave with a carrier frequency of 38 GHz. By using a drone and a commercial Lidar, we were able to verify that the radar can measure reflectivities in the order of −60 dBZ at 500 m of distance, with a range resolution of 20 m. The lower needed range coverage imposed by our case of study enabled a significant reduction of the instrument cost compared to existent alternatives. The portability and low-cost of the designed instrument enable its implementation in a distributed manner along the coastal mountain range, as well as its use in medium-size aerial vehicles or balloons to study higher layers. The main features, limitations, and possible improvements to the current instrument are discussed.Remote Sensing2072-4292 Reuters ISIagricultural robots, antennas, atmospheric boundary layer, climate models, costs, ecosystems, fog, optical radar, topography, application fields, cloud radar systems, coastal ecosystems, coastal topography, distributed measurements, frequency-modulated continuous waves, physical parameters, scientific researches, radar measurement
Influence of coastal upwelling on micro-phytoplankton variability at Valparaíso Bay (~33ºS), Central ChileAparicio-Rizzo, Pilar; Masotti, Italo; Landaeta, Mauricio F.Zonas Costeras2020.010.22370/rbmo.2020.55.1.2353In this work 10 years of data (1986-1996) from a fixed station located in the northern part of Valparaíso Bay (33º00’S; 71º35’W) were analysed to study the influence of coastal upwelling activity on the temporal variation of micro-phytoplankton (20-200 μm) and their relationship with oceanographic conditions. The upwelling activity at the bay was associated to semi-annual wind regime with an intensification of upwelling-favourable S-SW winds from September to March followed by a decrease and the occurrence of downwelling events from April to August. Oceanographic conditions showed the ascent of cold, nutrient-rich salty water in spring (September-November). However, during summertime under highest upwelling index, thermal stratification conditions were registered. This stratification might be associated to either the solar radiation or the presence of an upwelling shadow area in the bay. The upwelling period had the highest micro-phytoplankton abundance mainly dominated by diatoms. This period was associated with an increase in biomass and richness in the bay. Meanwhile during non-upwelling period —under homogenous conditions of temperature, salinity and nutrients— an increase in diversity (but low abundance and richness) associated to dinoflagellates and silicoflagellates was noted. Therefore, the results suggest the presence of a bi-modal regime of micro-phytoplankton in the bay in response to changes in oceanographic conditions related to local wind forcing and mixing/stratification.Revista de Biología Marina y Oceanografía0718-1957, 0717-3326 Reuters ISIcoastal zone, phytoplankton, stratification, temporal variation, upwelling, wind forcing, chile, valparaiso bay, valparaiso [chile], bacillariophyta, costera, dictyochophyceae, dinophyceae
Connection between Antarctic Ozone and Climate: Interannual Precipitation Changes in the Southern HemisphereDamiani, Alessandro; Cordero, Raul R.; Llanillo, Pedro J.; Feron, Sarah; Boisier, Juan P.; Garreaud, Rene; Rondanelli, Roberto; Irie, Hitoshi; Watanabe, ShingoZonas Costeras; Agua y Extremos2020.010.3390/atmos11060579In this study, we explored the connection between anomalies in springtime Antarctic ozone and all-year precipitation in the Southern Hemisphere by using observations from 1960–2018 and coupled simulations for 1960–2050. The observations showed that this correlation was enhanced during the last several decades, when a simultaneously increased coupling between ozone and Southern Annular Mode (SAM) anomalies became broader, covering most of the following summer and part of the previous winter. For eastern Australia, the ozone–precipitation connection shows a greater persistence toward the following summer than for other regions. On the other hand, for South America, the ozone–precipitation correlation seems more robust, especially in the early summer. There, the correlation also covers part of the previous winter, suggesting that winter planetary waves could affect both parameters. Further, we estimated the sensitivity of precipitation to changes in Antarctic ozone. In both observations and simulations, we found comparable sensitivity values during the spring–summer period. Overall, our results indicate that ozone anomalies can be understood as a tracer of stratospheric circulation. However, simulations indicate that stratospheric ozone chemistry still contributes to strengthening the interannual relationship between ozone and surface climate. Because simulations reproduced most of the observed connections, we suggest that including ozone variability in seasonal forecasting systems can potentially improve predictions.Atmosphere2073-4433 Reuters ISIozone layer, coupled simulation, precipitation change, seasonal forecasting, sensitivity values, southern annular mode, southern hemisphere, stratospheric circulations, stratospheric ozone chemistry, ozone, annual variation, anomaly, atmospheric chemistry, computer simulation, ozone, precipitation (climatology), regional climate, southern hemisphere, antarctica
Taxonomic Novelty and Distinctive Genomic Features of Hot Spring CyanobacteriaAlcorta, Jaime; Alarcón-Schumacher, Tomás; Salgado, Oscar; Díez, BeatrizZonas Costeras2020.010.3389/fgene.2020.568223Several cyanobacterial species are dominant primary producers in hot spring microbial mats. To date, hot spring cyanobacterial taxonomy, as well as the evolution of their genomic adaptations to high temperatures, are poorly understood, with genomic information currently available for only a few dominant genera, including Fischerella and Synechococcus. To address this knowledge gap, the present study expands the genomic landscape of hot spring cyanobacteria and traces the phylum-wide genomic consequences of evolution in high temperature environments. From 21 globally distributed hot spring metagenomes, with temperatures between 32 and 75°C, 57 medium- and high-quality cyanobacterial metagenome-assembled genomes were recovered, representing taxonomic novelty for 1 order, 3 families, 15 genera and 36 species. Comparative genomics of 93 hot spring genomes (including the 57 metagenome-assembled genomes) and 66 non-thermal genomes, showed that the former have smaller genomes and a higher GC content, as well as shorter proteins that are more hydrophilic and basic, when compared to the non-thermal genomes. Additionally, the core accessory orthogroups from the hot spring genomes of some genera had a greater abundance of functional categories, such as inorganic ion metabolism, translation and post-translational modifications. Moreover, hot spring genomes showed increased abundances of inorganic ion transport and amino acid metabolism, as well as less replication and transcription functions in the protein coding sequences. Furthermore, they showed a higher dependence on the CRISPR-Cas defense system against exogenous nucleic acids, and a reduction in secondary metabolism biosynthetic gene clusters. This suggests differences in the cyanobacterial response to environment-specific microbial communities. This phylum-wide study provides new insights into cyanobacterial genomic adaptations to a specific niche where they are dominant, which could be essential to trace bacterial evolution pathways in a warmer world, such as the current global warming scenario.Frontiers in Genetics1664-8021 Reuters ISIamino acid transporter, reduced nicotinamide adenine dinucleotide (phosphate) dehydrogenase (quinone), rna 16s, amino acid metabolism, article, bacterium isolation, bioinformatics, bioremediation, comparative genomics, crispr cas system, cyanobacterium, dna base composition, dna extraction, gene cluster, gene sequence, genetic transcription, genome size, genomics, geographic distribution, haplotype, heat shock, human, hydrophilicity, hydrophobicity, ion transport, metagenome, metagenomics, microbial community, microbial diversity, molecular genetics, nonhuman, phylogenomics, polyphyly, prevalence, protein function, protein processing, secondary metabolism, taxonomy, thermal spring
Fermentation and Anaerobic Oxidation of Organic Carbon in the Oxygen Minimum Zone of the Upwelling Ecosystem Off Concepción, in Central ChileSrain, Benjamín M.; Sobarzo, Marcus; Daneri, Giovanni; González, Humberto E.; Testa, Giovanni; Farías, Laura; Schwarz, Alex; Pérez, Norma; Pantoja-Gutiérrez, SilvioZonas Costeras2020.010.3389/fmars.2020.00533We studied the dynamics of fermentation and anaerobic degradation of organic matter at a fixed station in the Oxygen Minimum Zone (OMZ) within the Humboldt Current System off Concepción, central Chile. Products of the main anaerobic microbial reactions fermentation, denitrification, and reduction of Fe(OH)3 and SO42– were analyzed during laboratory incubations of OMZ waters. Fermentation of glucose and amino acids resulted in the production of volatile fatty acids, mainly acetate; these compounds were detected year-round in in situ water samples and were associated with high primary production rates and presence of O2-deficient waters at the sampling site. In contrast, whilst ethanol was produced from glucose fermentation by OMZ water microorganisms under laboratory conditions, it was not detected in the water column during the annual cycle. Evidence of acetate oxidation (which is thermodynamically feasible), with Fe(OH)3 as an electron acceptor, suggests that microbial activity could reduce solid-phase Fe carried by rivers using fermented metabolites in oxygen-depleted water, thus releasing dissolved bioavailable Fe. Here we present evidence for productivity-driven seasonality of biogeochemical cycles in the Humboldt system, supported by fermentation and anaerobic consumption of fermentation products oxidized by a variety of electron acceptors including NO3–, Fe(OH)3, and SO42–. Our results suggest that products of fermentation in the OMZ may provide a source of labile organics for advection to oxygenated waters of subantarctic origin during austral winter. Fermentation, anaerobic oxidation and associated advection of fermentation products are likely to be enhanced during the twenty-first century due both to temperature increase and decrease in dissolved O2 in the water column.Frontiers in Marine Science2296-7745 Reuters ISIacetate, anaerobic respiration, chile, fermentation, oxygen minimum zone, south east pacific, volatile fatty acids
Seasonal precipitation in South Central Chile: trends in extreme events since 1900González-Reyes, Álvaro; Jacques-Coper, Martin; Muñoz, Ariel AndresZonas Costeras; Agua y Extremos2020.010.20937/ATM.52871We study a regional precipitation time series, built upon seven meteorological records from South Central Chile (SCC; 37° - 42°S), which together cover the period 1900 - 2019. As a first objective, we investigated changes in the return period (RP) of dry ( P80) seasonal extreme events of precipitation (SEE), for each season. We observed a reduction in the RP of wet SEE during 1900 - 1950 in all seasons. Contrarily, the dry SEE RP shows a reduction from 1950 to the present in all seasons. This phenomenon is noteworthy since 1900 for summer and winter, and since 1930 for autumn. Spring registers a constant RP value from 1990 onwards. As a second objective, we study possible relationships between seasonal precipitation variability and climate modes, such as the Southern Annular Mode (SAM) and the Tripolar Index (TPI) of sea surface temperature (SST) over the Pacific Ocean. Summer and autumn precipitation register a significant negative correlation with SAM activity at interannual and decadal scales, while winter and spring precipitation show a significant positive correlation with SST variability over multiple regions of the Pacific Ocean (including the tropics and New Zealand) and the Southern Ocean (Amundsen-Bellingshausen Sea). Finally, we confirm that SAM strongly modulates precipitation in SCC, especially in autumn, and that SEE variability in SCC is considerably characterized by climate modes of tropical and extra-tropical origin.Atmósfera Reuters ISIextreme seasonal precipitation events, south-central chile, southern annular mode (sam), tripole index of sea surface temperature of the pacific ocean (tpi)
Evidence of climate-driven changes on atmospheric, hydrological, and oceanographic variables along the Chilean coastal zoneGrez, Patricio Winckler; Aguirre, Catalina; Farías, Laura; Contreras-López, Manuel; Masotti, ÍtaloZonas Costeras2020.010.1007/s10584-020-02805-3Abstract The Chilean coastal zone (CCZ) is subjected to a complex spectrum of anthropogenic, geophysical, biogeochemical, and climate-driven perturbations. Potentially affected variables including atmospheric sea level pressure ( Pa ), alongshore wind, sea surface temperature ( SST ), chlorophyll-a, rainfall, river discharge, relative mean sea level ( RMSL ), and wave climate are studied using in situ and satellite records, hindcasts, and reanalysis datasets. Linear temporal trends and correlations of anomalies are estimated between 18°S and 55°S along the CCZ. The comparison of some of the variables is achieved by means of a strict homogenization procedure on a monthly basis for 35 years. Our findings show that the poleward drift and strengthening of the Southeast Pacific Subtropical Anticyclone (SPSA) partially explains the increase in Pa and reduction in rainfall and river discharge. The enhancement of alongshore winds, also attributable to changes in the SPSA, increases coastal upwelling, which in turn could reduce SST and increase chlorophyll-a. Despite differential latitudinal responses, increasing wave heights and a southward rotation are evidenced. RMSL does not show significant variation as it is presumably affected by seafloor changes during the seismic cycle. Though some correlations are evidenced, the influence of climate variability at decadal scale (PDO, SAM) may be affecting the detected trends due to the short length of available data. Impacts on coastal communities, infrastructure, and ecosystems are discussed, aiming to highlight that coastal vulnerabilities and risk management should be based on the cumulative impacts of these variables.Climatic Change0165-0009, 1573-1480 Reuters ISIchlorophyll, coastal zones, ocean currents, rain, risk management, surface waters, climate variability, coastal communities, coastal upwelling, cumulative impacts, homogenization procedure, sea level pressure, sea surface temperature (sst), subtropical anticyclone, sea level, anthropogenic effect, biogeochemistry, climate change, coastal zone, complexity, geophysical method, mantle upwelling, perturbation, rainfall, river discharge, satellite data, sea level pressure, sea surface temperature, wave climate, pacific ocean, pacific ocean (southeast)
Recent Near-surface Temperature Trends in the Antarctic Peninsula from Observed, Reanalysis and Regional Climate Model DataBozkurt, D.; Bromwich, D. H.; Carrasco, J; Hines, Keith M.; Maureira, J. C.; Rondanelli, R.Zonas Costeras; Agua y Extremos2020.010.1007/s00376-020-9183-xThis study investigates the recent near-surface temperature trends over the Antarctic Peninsula. We make use of available surface observations, ECMWF’s ERA5 and its predecessor ERA-Interim, as well as numerical simulations, allowing us to contrast different data sources. We use hindcast simulations performed with Polar-WRF over the Antarctic Peninsula on a nested domain configuration at 45 km (PWRF-45) and 15 km (PWRF-15) spatial resolutions for the period 1991-2015. In addition, we include hindcast simulations of KNMI-RACMO21P obtained from the CORDEX-Antarctica domain (~50 km) for further comparisons. Results show that there is a marked windward warming trend except during summer. This windward warming trend is particularly notable in the autumn season and likely to be associated with the recent deepening of the Amundsen/Bellingshausen Sea low and warm advection towards the Antarctic Peninsula. On the other hand, an overall summer cooling is characterized by the strengthening of the Weddell Sea low as well as an anticyclonic trend over the Amundsen Sea accompanied by northward winds. The persistent cooling trend observed at the Larsen Ice Shelf station is not captured by ERA-Interim, whereas hindcast simulations indicate that there is a clear pattern of windward warming and leeward cooling. Furthermore, larger temporal correlations and lower differences exhibited by PWRF-15 illustrate the existence of the added value in the higher spatial resolution simulation.Advances in Atmospheric Sciences0256-1530, 1861-9533 Reuters ISIadded value, amundsen/bellingshausen sea, cloud computing, dynamical downscaling, reanalysis, temperature trend, weddell sea, 宋米荣
Temporal Variability in Net Primary Production in an Upwelling Area off Central Chile (36°S)Testa, Giovanni; Masotti, Italo; Farías, LauraZonas Costeras2018.010.3389/fmars.2018.00179The temporal variability of Net Primary Production (NPP) off central Chile (36°S, 73°W), an area subjected to seasonal coastal upwelling, was analyzed using monthly in situ 13C incubations within the photic zone, along with bio-oceanographic variables from a fixed time series station; and satellite NPP estimations (NPPE) from the Vertically Generalized Production Model between 2006 and 2015. NPP and NPPE rates varied from 0.03 to 18.29 and from 0.45 to 9.07 g C m−2 d−1, respectively. Both rates were fairly well correlated with each other (r2 = 0.61), but when these data were separated into two periods, higher r2 value was found during winter (r2 = 0.70) with respect to the rest of the year (r2 = 0.24); the latter correlation was partially due to increased weekly NPPE variability during active and relaxed upwelling events. NPP rates along with other biophysical variables allowed for a division of the annual cycle into three distinct periods: September to January (high productivity, mean integrated NPP rates of 4.0 g C m−2 d−1), February to March (intermediate productivity, mean integrated NPP rates of 1.4 g C m−2 d−1), and May to August (basal level, mean integrated NPP rates of 0.5 g C m−2 d−1). NPP appeared to be partially controlled by nutrient inputs, either from upwelling (September-April) and river discharge (May-August), maintaining high NPP rates throughout the entire year, with an annual mean NPP rate of 1.1 kg C m−2 yr−1. In this region, El Niño Southern Oscillation events did not appear to impact the NPP interannual variability.Frontiers in Marine Science2296-7745 Reuters ISIcentral chile, coastal upwelling, el niño southern oscillation, primary production rates, river discharge
Toward High-Resolution Vertical Measurements of Dissolved Greenhouse Gases (Nitrous Oxide and Methane) and Nutrients in the Eastern South PacificTroncoso, Macarena; Garcia, Gerardo; Verdugo, Josefa; Farías, LauraZonas Costeras2018.010.3389/fmars.2018.00148In this study, in situ, real-time and high-resolution vertical measurements of dissolved greenhouse gases (GHGs) such as nitrous oxide (N2O) and methane (CH4) and nutrients are reported for the eastern South Pacific (ESP); a region with marked zonal gradients, ranging from highly productive and suboxic conditions in coastal upwelling systems to oligotrophic and oxygenated conditions in the subtropical gyre. Four high-resolution vertical profiles for gases (N2O and CH4) and nutrients (NO−3 and PO3−4) were measured using a Pumped Profiling System (PPS), connected with a liquid degassing membrane coupled with Cavity Ring-Down Spectroscopy (CRDS) and a nutrient auto-analyzer, respectively. The membrane-CRDS system maintains a linear response over a wide range of gas concentrations, detecting N2O and CH4 levels as low as 0.0774 ± 0.0004 and 0.1011 ± 0.001 ppm, respectively. Continuous profiles for gases and nutrients were similar to those reported throughout the ESP, with pronounced N2O and CH4 peaks at the upper oxycline and at the base of the euphotic zone and pycnocline, respectively, in the coastal zone; but almost constant depth profiles in the subtropical gyre. Additionally, other vertical gas and nutrient structures were observed using continuous sampling, which would not have been detected by discrete sampling. Our results demonstrate that continuous measurements can be a potentially useful methodology for future GHGs cycle studies.Frontiers in Marine Science2296-7745 Reuters ISIcontinuous profiles, eastern south pacific, methane, nitrous oxide, nutrients
The influence of river discharge on nutrient export and phytoplankton biomass off the Central Chile coast (33º-37ºS). Seasonal cycle and interannual variabilityMasotti, Italo; Aparicio-Rizzo, Pilar; Yevenes, Mariela A; Garreaud, Rene; Farias, LauraZonas Costeras2018.010.3389/fmars.2018.00423Using in situ hydro-chemical data and MODIS-SeaWiFS ocean color images as a proxy of river plumes and phytoplankton biomass from 2000 to 2014, this study documents the temporal co-variability of river discharge, plume area, nitrate and phosphate export and phytoplankton biomass in the coastal waters off Central Chile (33º-37ºS). Five major rivers (Maipo, Mataquito, Maule, Itata and Biobío) drain into this region with annual mean discharge ranging from 120 to 1000 m3 s-1. River discharge and coastal plume area present a marked seasonal cycle, reaching maximum values during the winter rainy season (June-September). Export of riverine nutrients also peaks in winter, leading to an increase in phytoplankton biomass within the plumes that can be twice larger than the background values in coastal areas away from the river mouths. Wintertime river discharge, plume area and nutrient export are also correlated at interannual time scales. During a recent extended dry period (2010-2014), river discharges, plume areas and nutrient export clearly decreased by about 50% compared to historical values, reducing significantly the size of the chlorophyll pool within plumes off Central Chile during winter. The potential impacts of droughts are discussed in terms of coastal ecology and primary production, a highly relevant issue considering the projections of a dry climate over Central Chile in the future. Systematic evidence of mega-drought effects upon coastal productivity still does not exist, but it remains a priority to further investigate and quantify these impacts.Frontier in Marine Science2296-774527Thomson Reuters ISIcentral chile, drought, nutrient export, phytoplankton biomass, river discharge, satellite remote sensing
Inter-annual variability of oceanographic conditions and phytoplankton in Valparaíso Bay (~33°S), central ChileAparicio-Rizzo, Pilar; Masotti, ItaloZonas Costeras2019.010.22370/rbmo.2019.54.1.1495The inter-annual variability of oceanographic conditions and phytoplankton abundance and biomass was studied using 10 years (1986-1996) of in situ observations at a fixed station in Valparaíso Bay (~33ºS). The time series analysis revealed that strong S-SW winds drive a quasi-permanent upwelling activity that maintain the nutrients availability in the water column to fuel the phytoplankton in the bay. The most important changes in bio-oceanographic conditions were observed during 1987 El Niño event, which was characterized by higher temperatures but lower values for salinity, nitrate, and phosphate concentrations, together with a decrease of phytoplankton biomass compared to 1988 La Niña event when colder, saltier, and nutrient-rich upwelled water were observed. High Aconcagua River discharges were observed during the El Niño conditions (1987-1988 and 1993), which led to a decrease in surface salinity and a high abundance of dinoflagellates. Two periods with differences in bio-oceanographic conditions were observed; 1988-1992 showed lower temperatures but higher nutrients (nitrate), phytoplankton biomass and abundance of diatoms than 1993-1996 period. Throughout the study period, positive trends in upwelling activity was registered accompanied by a fall in phytoplankton biomass and dinoflagellate abundance. This paper provides new evidences concerning the influence of El Niño Southern Oscillation (ENSO) in phytoplankton and oceanographic conditions in the coastal upwelling off central Chile.Revista de Biología Marina y Oceanografía0717-3326 Reuters ISIabundance, annual variation, biomass, dinoflagellate, el nino-southern oscillation, environmental factor, phytoplankton, surface temperature, time series analysis, upwelling, aconcagua river, chile, valparaiso bay, valparaiso [chile], bacillariophyta, dinophyceae
The Central Chile Mega Drought (2010–2018): A climate dynamics perspectiveGarreaud, R.; Boisier, J. P.; Rondanelli, R.; Montecinos, A.; Sepúlveda, H.; Veloso‐Aguila, D.Zonas Costeras; Agua y Extremos2020.010.1002/joc.6219Central Chile, home to more than 10 million inhabitants, has experienced an uninterrupted sequence of dry years since 2010 with mean rainfall deficits of 20–40%. The so‐called Mega Drought (MD) is the longest event on record and with few analogues in the last millennia. It encompasses a broad area, with detrimental effects on water availability, vegetation and forest fires that have scaled into social and economical impacts. Observations and reanalysis data reveal that the exceptional length of the MD results from the prevalence of a circulation dipole‐hindering the passage of extratropical storms over central Chile—characterized by deep tropospheric anticyclonic anomalies over the subtropical Pacific and cyclonic anomalies over the Amundsen–Bellingshausen Sea. El Niño Southern Oscillation (ENSO) is a major modulator of such dipole, but the MD has occurred mostly under ENSO‐neutral conditions, except for the winters of 2010 (La Niña) and 2015 (strong El Niño). Climate model simulations driven both with historical forcing (natural and anthropogenic) and observed global SST replicate the south Pacific dipole and capture part of the rainfall anomalies. Idealized numerical experiments suggest that most of the atmospheric anomalies emanate from the subtropical southwest Pacific, a region that has experienced a marked surface warming over the last decade. Such warming may excite atmospheric Rossby waves whose propagation intensifies the circulation pattern leading to dry conditions in central Chile. On the other hand, anthropogenic forcing (greenhouse gases concentration increase and stratospheric ozone depletion) and the associated positive trend of the Southern Annular Mode also contribute to the strength of the south Pacific dipole and hence to the intensity and longevity of the MD. Given the concomitance of the seemingly natural (ocean sourced) and anthropogenic forcing, we anticipate only a partial recovery of central Chile precipitation in the decades to come.International Journal of Climatology0899-8418 Reuters ISIatmospheric pressure, climate change, deforestation, drought, greenhouse gases, mechanical waves, oceanography, ozone layer, rain, tropics, anthropogenic forcing, anticyclonic anomalies, chile, climate model simulations, enso, numerical experiments, south america, stratospheric ozone depletion, climate models, antarctic oscillation, anthropogenic effect, atmospheric dynamics, climate change, climate forcing, drought, el nino-southern oscillation, pacific decadal oscillation, precipitation (climatology), rossby wave, amundsen sea, bellingshausen sea, chile, pacific ocean, pacific ocean (south), pacific ocean (subtropical), southern ocean
Elucidating Viral Communities During a Phytoplankton Bloom on the West Antarctic PeninsulaAlarcón-Schumacher, Tomás; Guajardo-Leiva, Sergio; Antón, Josefa; Díez, BeatrizZonas Costeras2019.010.3389/fmicb.2019.01014In Antarctic coastal waters where nutrient limitations are low, viruses are expected to play a major role in the regulation of bloom events. Despite this, research in viral identification and dynamics is scarce, with limited information available for the Southern Ocean (SO). This study presents an integrative-omics approach, comparing variation in the viral and microbial active communities on two contrasting sample conditions from a diatom-dominated phytoplankton bloom occurring in Chile Bay in the West Antarctic Peninsula (WAP) in the summer of 2014. The known viral community, initially dominated by Myoviridae family (∼82% of the total assigned reads), changed to become dominated by Phycodnaviridae (∼90%), while viral activity was predominantly driven by dsDNA members of the Phycodnaviridae (∼50%) and diatom infecting ssRNA viruses (∼38%), becoming more significant as chlorophyll a increased. A genomic and phylogenetic characterization allowed the identification of a new viral lineage within the Myoviridae family. This new lineage of viruses infects Pseudoalteromonas and was dominant in the phage community. In addition, a new Phycodnavirus (PaV) was described, which is predicted to infect Phaeocystis antarctica, the main blooming haptophyte in the SO. This work was able to identify the changes in the main viral players during a bloom development and suggests that the changes observed in the virioplankton could be used as a model to understand the development and decay of blooms that occur throughout the WAP. © 2019 Alarcón-Schumacher, Guajardo-Leiva, Antón and Díez. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.Frontiers in Microbiology1664-302X Reuters ISIcapsid protein, chlorophyll a, dna polymerase, ribulosebisphosphate carboxylase, rna 16s, transcriptome, algal bloom, alteromonadales, antarctica, article, asfarviridae, bayes theorem, bootstrapping, chlorophyll content, cryptophyta, diatom, dna base composition, environmental factor, flavobacteriales, gammaproteobacteria, gene sequence, genetic correlation, genetic similarity, genome analysis, haptophyta, maximum likelihood method, metagenome, metagenomics, microbial community, monte carlo method, myoviridae, nonhuman, oxygen concentration, phycodnaviridae, phylogeny, population abundance, pseudoalteromonas phage pm2, quality control, rna sequence, rna virus, seasonal variation, single-stranded rna virus, siphoviridae, taxonomy, virus cell interaction, virus identification
Summertime precipitation deficits in the southern Peruvian highlands since 1964Imfeld, Noemi; Barreto Schuler, Christian; Correa Marrou, Kris Milagros; Jacques‐Coper, Martín; Sedlmeier, Katrin; Gubler, Stefanie; Huerta, Adrian; Brönnimann, StefanZonas Costeras2019.010.1002/joc.6087Precipitation deficits remain a concern to the rural population in the southern Peru-vian highlands and knowledge about their occurrence is lacking because of scarcedata availability. For mountainous regions with sparse station networks, reanalysescan provide valuable information; however, known limitations in reproducing pre-cipitation are aggravated due to unresolved topographical effects. In this study, weassess in a first step the representation of precipitation during the rainy season(January–February–March) in seven reanalysis data sets in comparison to a newlygenerated gridded precipitation data set for Peru. In a second step, we assess sum-mer precipitation deficits in Peru during the second half of the 20th century.In the reanalyses data sets, we find biases strongly influenced by the topography ofthe models and low correlations for the rainy season. Thus, reanalyses do not solvethe problem of data scarcity for this region either. Furthermore, we confirm that ElNiño is not a sufficient stratification criterion for precipitation deficits during therainy season (JFM) in the southern Peruvian highlands. Based on observationalrecords and reanalyses, a considerable fraction of inter-annual variability of precipi-tation can be explained through upper-tropospheric zonal wind anomalies. Westerlywind anomalies, often related to the warming of the troposphere during an El Niñoevent, lead to dry conditions, but not all El Niño events produce these westerly windanomalies. Atmospheric simulations indicate differences between precipitation defi-cits in central Pacific and eastern Pacific El Niño flavours, which cannot beaddressed in observations due to reduced record length: Droughts in the southernPeruvian Andes during eastern Pacific El Niño events seem to be related to a stron-ger warming in the troposphere above the central Pacific ocean, whereas this is notthe case for droughts during central Pacific El Niño events. These results, however,need to be further corroborated by model studies and palaeoclimatological research.International Journal of Climatology0899-8418 Reuters ISIdrought, rain, topography, troposphere, atmospheric simulations, enso, interannual variability, mountain, peru, precipitation deficits, reanalysis, topographical effects, population statistics, annual variation, atmospheric modeling, data assimilation, drought, el nino-southern oscillation, mountain region, precipitation (climatology), rainfall, summer, peru
A Harmonized Nitrous Oxide (N2O) Ocean Observation Network for the 21st CenturyBange, Hermann W.; Arévalo-Martínez, Damian L.; de la Paz, Mercedes; Farías, Laura; Kaiser, Jan; Kock, Annette; Law, Cliff S.; Rees, Andrew P.; Rehder, Gregor; Tortell, Philippe D.; Upstill-Goddard, Robert C.; Wilson, Samuel T.Zonas Costeras2019.010.3389/fmars.2019.00157Nitrous oxide (N2O) is an important atmospheric trace gas involved in tropospheric warming and stratospheric ozone depletion. Estimates of the global ocean contribution to N2O emissions average 21% (range: 10 to 53%). Ongoing environmental changes such as warming, deoxygenation and acidification are affecting oceanic N2O cycling and emissions to the atmosphere. International activities over the last decades aimed at improving estimates of global N2O emissions, including (i) the MarinE MethanE and NiTrous Oxide database (MEMENTO) for archiving of quality-controlled data, and (ii) a recent large-scale inter-laboratory comparison by Working Group 143 of the Scientific Committee on Ocean Research (SCOR). To reduce uncertainties in oceanic N2O emission estimates and to characterize the spatial and temporal variability in N2O distributions in a changing ocean, we propose the establishment of a harmonized N2O Observation Network (N2O-ON) combining discrete and continuous data from various platforms. The network will integrate observations obtained by calibrated techniques, using time series measurements at fixed stations and repeated hydrographic sections on voluntary observing ships and research vessels. In addition to exploiting existing oceanographic infrastructure, we propose the establishment of central calibration facilities in selected international laboratories to improve accuracy, and ensure standardization and comparability of N2O measurements. Final data products will include a harmonized global N2O concentration and emission fields for use in model validation and projections of future oceanic N2O emissions, to inform the global research community and policy makers.Frontiers in Marine Science2296-7745 Reuters ISIcalibration, nitrous oxide, observation network, oceanic distribution, oceanic emissions
Anthropogenic drying in central-southern Chile evidenced by long-term observations and climate model simulationsBoisier, Juan P.; Alvarez-Garretón, Camila; Cordero, Raúl R.; Damiani, Alessandro; Gallardo, Laura; Garreaud, René D.; Lambert, Fabrice; Ramallo, Cinthya; Rojas, Maisa; Rondanelli, RobertoCiudades Resilientes; Zonas Costeras; Agua y Extremos; Gobernanza e Interfaz Ciencia y Política2018.010.1525/elementa.328The socio-ecological sensitivity to water deficits makes Chile highly vulnerable to global change. New evidence of a multi-decadal drying trend and the impacts of a persistent drought that since 2010 has affected several regions of the country, reinforce the need for clear diagnoses of the hydro-climate changes in Chile. Based on the analysis of long-term records (50+ years) of precipitation and streamflow, we confirm a tendency toward a dryer condition in central-southern Chile (30–48°S). We describe the geographical and seasonal character of this trend, as well as the associated large-scale circulation pat- terns. When a large ensemble of climate model simulations is contrasted to observations, anthropogenic forcing appears as the leading factor of precipitation change. In addition to a drying trend driven by greenhouse gas forcing in all seasons, our results indicate that the Antarctic stratospheric ozone deple- tion has played a major role in the summer rainfall decline. Although average model results agree well with the drying trend’s seasonal character, the observed change magnitude is two to three times larger than that simulated, indicating a potential underestimation of future projections for this region. Under present-day carbon emission rates, the drying pathway in Chile will likely prevail during the next decades, although the summer signal should weaken as a result of the gradual ozone layer recovery. The trends and scenarios shown here pose substantial stress on Chilean society and its institutions, and call for urgent action regarding adaptation measures.Elementa: Science of the Anthropocene2325-1026 Reuters ISIanthropogenic effect, carbon emission, climate modeling, drought, greenhouse gas, long-term change, ozone depletion, simulation, streamflow, trend analysis, vulnerability, chile
Strongest MJO on Record Triggers Extreme Atacama Rainfall and Warmth in AntarcticaRondanelli, R.; Hatchett, B.; Rutllant, J.; Bozkurt, D.; Garreaud, R.Zonas Costeras; Agua y Extremos; Transversal2019.010.1029/2018GL081475Tropical perturbations have been shown theoretically and observationally to excite long range atmospheric responses in the form of Rossby wave teleconnections that result from the equator to pole gradient of planetary vorticity. An extreme teleconnection event occurred during March 2015 in the Southeastern Pacific. As a result, extreme high temperatures were observed in Southwestern South America and the Antarctic Peninsula simultaneously with an extreme rainfall and flood event in the hyperarid Atacama desert.%%%%%%We show that the origin of these seemingly disconnected extreme events can be traced to a Rossby wave response to the strongest Madden‐Julian Oscillation (MJO) on record in the tropical central Pacific. A barotropic wavenumber 3 to 4 perturbation with group velocity between 15 to 30 m/s is consistent with the trajectory and timing followed by the upper level anomalies radiating away from the tropics after the MJO episode.Geophysical Research Letters0094-8276 Reuters ISIflood control, floods, mechanical waves, oil well flooding, rain, tropics, antarctic peninsula, antarctica, atmospheric response, climate dynamics, extremes, madden-julian oscillation, rossby wave, rossby wave response, climatology, air-sea interaction, barotropic wave, climate change, extreme event, flood, flooding, high temperature, madden-julian oscillation, rainfall, rossby wave, teleconnection, wave velocity, antarctic peninsula, antarctica, atacama desert, chile, pacific ocean, pacific ocean (central), pacific ocean (southeast), south america, west antarctica
Black carbon and other light-absorbing impurities in snow in the Chilean AndesRowe, Penny M.; Cordero, Raul R.; Warren, Stephen G.; Stewart, Emily; Doherty, Sarah J.; Pankow, Alec; Schrempf, Michael; Casassa, Gino; Carrasco, Jorge; Pizarro, Jaime; MacDonell, Shelley; Damiani, Alessandro; Lambert, Fabrice; Rondanelli, Roberto; Huneeus, Nicolas; Fernandoy, Francisco; Neshyba, StevenCiudades Resilientes; Zonas Costeras2019.010.1038/s41598-019-39312-0Vertical profiles of black carbon (BC) and other light-absorbing impurities were measured in seasonal snow and permanent snowfields in the Chilean Andes during Austral winters 2015 and 2016, at 22 sites between latitudes 18°S and 41°S. The samples were analyzed for spectrally-resolved visible light absorption. For surface snow, the average mass mixing ratio of BC was 15 ng/g in northern Chile (18–33°S), 28 ng/g near Santiago (a major city near latitude 33°S, where urban pollution plays a significant role), and 13 ng/g in southern Chile (33–41°S). The regional average vertically-integrated loading of BC was 207 µg/m 2 in the north, 780 µg/m 2 near Santiago, and 2500 µg/m 2 in the south, where the snow season was longer and the snow was deeper. For samples collected at locations where there had been no new snowfall for a week or more, the BC concentration in surface snow was high (~10–100 ng/g) and the sub-surface snow was comparatively clean, indicating the dominance of dry deposition of BC. Mean albedo reductions due to light-absorbing impurities were 0.0150, 0.0160, and 0.0077 for snow grain radii of 100 µm for northern Chile, the region near Santiago, and southern Chile; respective mean radiative forcings for the winter months were 2.8, 1.4, and 0.6 W/m 2 . In northern Chile, our measurements indicate that light-absorption by impurities in snow was dominated by dust rather than BC. © 2019, The Author(s).Scientific Reports2045-2322 Reuters ISI
Greenhouse gases, nutrients and the carbonate system in the Reloncaví Fjord (Northern Chilean Patagonia): Implications on aquaculture of the mussel, Mytilus chilensis, during an episodic volcanic eruptionYevenes, Mariela A.; Lagos, Nelson A.; Farías, Laura; Vargas, Cristian A.Zonas Costeras2019.010.1016/j.scitotenv.2019.03.037This study investigates the immediate and mid-term effects of the biogeochemical variables input into the Reloncaví fjord (41°40′S; 72°23′O) as a result of the eruption of Calbuco volcano. Reloncaví is an estuarine system supporting one of the largest mussels farming production within Northern Chilean-Patagonia. Field-surveys were conducted immediately after the volcanic eruption (23–30 April 2015), one month (May 2015), and five months posterior to the event (September 2015). Water samples were collected from three stations along the fjord to determine greenhouse gases [GHG: methane (CH 4 ), nitrous oxide (N 2 O)], nutrients [NO 3 − , NO 2 − , PO 4 3− , Si(OH) 4 , sulphate (SO 4 2− )], and carbonate systems parameters [total pH (pHT), temperature, salinity, dissolved oxygen (O 2 ), and total alkalinity (AT)]. Additionally, the impact of physicochemical changes in the water column on juveniles of the produced Chilean blue mussel, Mytilus chilensis, was also studied. Following the eruption, a large phytoplankton bloom led to an increase in pH T , due to the uptake of dissolved-inorganic carbon in photic waters, potentially associated with the runoff of continental soil covered in volcanic ash. Indeed, high surface SO 4 2− and GHG were observed to be associated with river discharges. No direct evidence of the eruption was observed within the carbonate system. Notwithstanding, a vertical pattern was observed, with an undersaturation of aragonite (Ω Ar < 1) both in brackish surface (<3 m) and deep waters (>10 m), and saturated values in subsurface waters (3 to 7 m). Simultaneously, juvenile mussel shells showed maximized length and weight at 4 m depth. Results suggest a localized impact of the volcanic eruption on surface GHG, nutrients and short-term effects on the carbonate system. Optimal conditions for mussel calcification were identified within a subsurface refuge in the fjord. These specific attributes can be integrated into adaptation strategies by the mussel aquaculture industry to confront ocean acidification and changing runoff conditions. © 2019 Elsevier B.V.Science of The Total Environment0048-9697 Reuters ISIalkalinity, aquaculture, biomineralization, carbonation, dissolved oxygen, greenhouse gases, molluscs, nitrogen oxides, nutrients, runoff, sulfur compounds, surface discharges, adaptation strategies, aquaculture industry, chilean patagonian fjord, dissolved inorganic carbon, mussel farming, ocean acidifications, physico-chemical changes, volcanic event, volcanoes, calcium carbonate, carbonic acid, dissolved oxygen, methane, nitrous oxide, sulfate, surface water, carbonic acid, methane, nitrous oxide, sea water, adaptive management, biogeochemical cycle, carbonate system, chemical oceanography, greenhouse gas, mussel culture, nutrient, ocean acidification, volcanic eruption, alkalinity, aquaculture, article, biogeochemical cycle, chilean, estuary, greenhouse gas, mussel, mytilus chilensis, nonhuman, ph, physical chemistry, phytoplankton, priority journal, runoff, salinity, temperature, volcanic ash, volcano, water sampling, analysis, animal, aquaculture, body constitution, chemistry, chile, environmental monitoring, greenhouse gas, mytilus, physiology, season, volcano, calbuco volcano, chile, los lagos, reloncavi fjord, mytilus chilensis, mytilus edulis, animals, aquaculture, body constitution, carbonates, chile, environmental monitoring, greenhouse gases, methane, mytilus, nitrous oxide, nutrients, seasons, seawater, volcanic eruptions
Dynamical downscaling over the complex terrain of southwest South America: present climate conditions and added value analysisBozkurt, Deniz; Rojas, Maisa; Boisier, Juan Pablo; Rondanelli, Roberto; Garreaud, René; Gallardo, LauraCiudades Resilientes; Zonas Costeras; Agua y Extremos; Gobernanza e Interfaz Ciencia y Política; Transversal2019.010.1007/s00382-019-04959-yThis study evaluates hindcast simulations performed with a regional climate model (RCM, RegCM4) driven by reanalysis data (ERA-Interim) over the Pacific coast and Andes Cordillera of extratropical South America. A nested domain configuration at \(0.44^{\circ }\) ( \(\sim\) 50 km) and \(0.09^{\circ }\) ( \(\sim\) 10 km) spatial resolutions is used for the simulations. RegCM4 is also driven by a global climate model (GCM, MPI-ESM-MR) on the same domain configuration to asses the added values for temperature and precipitation (historical simulations). Overall, both 10 km hindcast and historical simulation results are promising and exhibit a better representation of near-surface air temperature and precipitation variability compared to the 50 km simulations. High-resolution simulations suppress an overestimation of precipitation over the Andes Cordillera of northern Chile found with the 50 km simulations. The simulated daily temperature and precipitation extreme indices from 10 km hindcast simulation show a closer estimation of the observed fields. A persistent warm bias ( \(\sim +\,{4\,}^{\circ }\hbox {C}\) ) over the Atacama Desert in 10 km hindcast simulation reveals the complexity in representing land surface and radiative processes over the desert. Difficulties in capturing the temperature trend in northern Chile are notable for both hindcast simulations. Both resolutions exhibit added values for temperature and precipitation over large parts of Chile, in particular, the 10 km resolves the coastal-valley Andes transitions over central Chile. Our results highlight that resolutions coarser than 50 km (e.g., GCMs and reanalysis) miss important climate gradients imposed by complex topography. Given that the highest spatial resolution of the current regional simulations over the South America is about 50 km, higher resolutions are important to improve our understanding of the dynamical processes that determine climate over complex terrain and extreme environments.Climate Dynamics0930-7575 Reuters ISIclimate conditions, climate modeling, climate variation, complex terrain, downscaling, regional climate, spatial analysis, temporal analysis, andes, atacama desert, chile, patagonia, equus asinus
Significant decrease of photovoltaic power production by aerosols. The case of Santiago de ChileDel Hoyo, Mirko; Rondanelli, Roberto; Escobar, RodrigoZonas Costeras2019.010.1016/j.renene.2019.10.005Santiago de Chile frequently suffers from atmospheric pollution that contributes to the decrease of solarirradiance on the surface, leading to losses in the energy output of photovoltaic systems. In this study, asimple model is used to estimate the effect of aerosols on the solar irradiance over the city throughoutthe year, using as input AERONET sunphotometer data and other in-situ measurements. The results showreductions of 3.5% and 14.1% for global horizontal and direct normal irradiance respectively and an in-crease of 35.4% for diffuse horizontal irradiance between the actual condition in Santiago and a hypo-thetical atmosphere free of aerosols. These effects translate approximately to an annual difference in theenergy output of 7.2% and 8.7% for monocrystalline and amorphous silicon PV technologies respec-tively, and an annual difference of 16.4% for a CPV technology, showing that aerosols can have a sig-nificant effect on the photovoltaic energy production.Renewable Energy0960-1481 Reuters ISIaerosols, amorphous silicon, photovoltaic cells, photovoltaic effects, solar power generation, solar radiation, aeronet, chile, photovoltaics, santiago, solar irradiances, air pollution, aeronet, aerosol, atmospheric pollution, data set, irradiance, photovoltaic system, silicon, chile, metropolitana, santiago [metropolitana]
Fischerella thermalis: a model organism to study thermophilic diazotrophy, photosynthesis and multicellularity in cyanobacteriaAlcorta, Jaime; Vergara-Barros, Pablo; Antonaru, Laura A.; Alcamán-Arias, María E.; Nürnberg, Dennis J.; Díez, BeatrizZonas Costeras2019.010.1007/s00792-019-01125-4The true-branching cyanobacterium Fischerella thermalis (also known as Mastigocladus laminosus) is widely distributed in hot springs around the world. Morphologically, it has been described as early as 1837. However, its taxonomic placement remains controversial. F. thermalis belongs to the same genus as mesophilic Fischerella species but forms a monophyletic clade of thermophilic Fischerella strains and sequences from hot springs. Their recent divergence from freshwater or soil true-branching species and the ongoing process of specialization inside the thermal gradient make them an interesting evolutionary model to study. F. thermalis is one of the most complex prokaryotes. It forms a cellular network in which the main trichome and branches exchange metabolites and regulators via septal junctions. This species can adapt to a variety of environmental conditions, with its photosynthetic apparatus remaining active in a temperature range from 15 to 58 °C. Together with its nitrogen-fxing ability, this allows it to dominate in hot spring microbial mats and contribute signifcantly to the de novo carbon and nitrogen input. Here, we review the current knowledge on the taxonomy and distribution of F.thermalis, its morphological complexity, and its physiological adaptations to an extreme environment.Extremophiles1431-0651 Reuters ISIacclimatization, biological model, cyanobacterium, evolution, heat, microbiology, physiology, thermal spring, trichome, acclimatization, biological evolution, cyanobacteria, hot springs, hot temperature, models, biological, trichomes
Validation of Cryogenic Vacuum Extraction of Pore Water from Volcanic Soils for Isotopic AnalysisRivera, Diego; Gutierrez, Karen; Valdivia-Cea, Walter; Zambrano-Bigiarini, Mauricio; Godoy-Faúndez, Alex; Álvez, Amaya; Farías, LauraZonas Costeras; Agua y Extremos2019.010.3390/w11112214Andean headwater catchments are key components of the hydrological cycle, given that they capture moisture, store water and release it for Chilean cities, industry, agriculture, and cities in Chile. However, knowledge about within-Andean catchment processes is far from clear. Most soils in the Andes derive from volcanic ash Andosols and Arenosols presenting high organic matter, high-water retention capacity and fine pores; and are very dry during summer. Despite their importance, there is little research on the hillslope hydrology of Andosols. Environmental isotopes such as Deuterium and 18-O are direct tracers for water and useful on analyzing water-soil interactions. This work explores, for the first time, the efficiency of cryogenic vacuum extraction to remove water from two contrasting soil types (Arenosols, Andosols) at five soil water retention energies (from −1500 to −33 kPa). Two experiments were carried out to analyse the impact of extraction time, and initial water content on the amount of extracted water, while a third experiment tested whether the cryogenic vacuum extraction changed the isotopic ratios after extraction. Minimum extraction times to recover over 90% of water initially in the soil samples were 40–50 min and varied with soil texture. Minimum volume for very dry soils were 0.2 mL (loamy sand) and 1 mL (loam). After extraction, the difference between the isotope standard and the isotopic values after extraction was acceptable. Thus, we recommend this procedure for soils derived from volcanic ashes.Water2073-4441 Reuters ISIcatchments, cryogenics, isotopes, runoff, soil moisture, textures, volcanoes, cryogenic vacuum, environmental isotopes, hillslope hydrology, initial water contents, isotopic analysis, soil water retention, volcanic soils, water-soil interaction, extraction, catchment, deuterium, equipment component, extraction method, hillslope, isotopic analysis, soil water potential, tracer, volcanic ash, volcanic soil, water content, water retention, water-rock interaction, andes, chile
Role of synoptic activity on projected changes in upwelling-favourable winds at the ocean’s eastern boundariesAguirre, Catalina; Rojas, Maisa; Garreaud, René D.; Rahn, David A.Zonas Costeras; Agua y Extremos; Gobernanza e Interfaz Ciencia y Política2019.010.1038/s41612-019-0101-9The climate of the ocean’s eastern boundaries is strongly influenced by subtropical anticyclones, which drive a surface wind stress that promotes coastal upwelling of nutrient-rich subsurface water that supports high primary productivity and an abundance of food resources. Understanding the projected response of upwelling-favourable winds to climate change has broad implications for coastal biogeochemistry, ecology, and fisheries. Here we use a reanalysis, an ensemble of global climate simulations, and an objective algorithm to track anticyclones to investigate the projected changes in upwelling-favourable wind events at the California, Canary, Humboldt, and Benguela coastal upwelling systems. Except for the north Pacific, we find consistent poleward shifts of mean and upper percentile daily winds over the ocean basins. We propose that extratropical, synoptic-scale migratory anticyclones that force intense coastal upwelling events—which become more frequent at higher latitudes and less frequent at lower latitudes in the future—play an important role in the projected changes in upwelling-favourable wind events in these coastal upwelling systems. These changes complement large-scale processes such as the poleward shift of the subtropical ridge (STR) and stationary subtropical highs. Hence, both extratropical and tropical processes need to be considered to fully explain projected changes at the coastal upwelling systems under anthropogenic climate change.npj Climate and Atmospheric Science2397-3722 Reuters ISIanthropogenic effect, anticyclone, climate change, climate modeling, computer simulation, ensemble forecasting, extratropical environment, marine atmosphere, numerical model, synoptic meteorology, tropical environment, weather forecasting, wind field, wind stress, angola, benguela, california, canada, canary islands, humboldt, saskatchewan, spain, united states
Soil microbial community responses to labile organic carbon fractions in relation to soil type and land use along a climate gradientRamírez, Paulina B.; Fuentes-Alburquenque, Sebastián; Díez, Beatriz; Vargas, Ignacio; Bonilla, Carlos A.Zonas Costeras2020.010.1016/j.soilbio.2019.107692There has been a growing interest in studying the labile C pool in order to promote the sequestration and stabilization of soil organic carbon (SOC). Although labile SOC fractions have emerged as standardized indicators because of their potential to detect early SOC trends over time, the relationships between microbial attributes and labile SOC remains poorly understood. In this study, we explored the influence of labile SOC fractions on the topsoil bacteria-archaea community across 28 sites with different land use, climate aridity, and soil types across a wide range of SOC content (0.6–12%) in central Chile. We applied Illumina sequencing to the 16S rRNA to examine shifts in the diversity and composition of these soil microbial communities. Additionally, labile SOC fractions such as the permanganate oxidizable carbon (POXC) and light fraction organic matter (LFOM), along with the soil physicochemical properties were analyzed. The results demonstrated that among all of the environmental factors tested, the pH, POXC/SOC ratio and LFOM were key drivers of microbial community structure (β-diversity). The α-diversity metrics exhibited a decreasing trend when aridity increased, and community structure was found to vary, with high POXC/SOC in sites associated with drier conditions. In addition, POXC/SOC ratios and LFOM were clearly related to shifts in the relative abundances of specific taxonomic groups at genera level. When there was high POXC/SOC and low LFOM content, members of Bacteroidetes (Adhaeribacter, Flavisolibacter, and Niastella), Proteobacteria (Skermanella, Ramlibacter, and Sphingomonas), and Archaea (Thaumarchaeota) were found to be the most dominant groups; however, the microbial taxa responded differently to both labile C fraction types. These results have implications for understanding how labile C content can potentially be used to predict shifts in the microbial community, thus facilitating the development of predictive ecosystem models, as well as early warning indicators for soil degradation.Soil Biology and Biochemistry00380717 Reuters ISIland use, microorganisms, organic carbon, physicochemical properties, rna, soils, 16s rrna gene, archaea, bacterial diversity, light fraction, soil ph, stabilization, bacterium, climate change, community response, community structure, environmental factor, geodiversity, microbial activity, microbial community, odor, ph, relative abundance, soil carbon, soil microorganism, soil organic matter, soil type, species diversity, topsoil, chile, adhaeribacter, bacteria (microorganisms), bacteroidetes, niastella, proteobacteria, ramlibacter, skermanella, sphingomonas
A multiscale analysis of the tornadoes of 30–31 May 2019 in south-central ChileBarrett, Bradford S.; Marin, Julio C.; Jacques-Coper, MartinZonas Costeras2020.010.1016/j.atmosres.2019.104811On 30 and 31 May 2019, tornadoes occurred in the cities of Los Angeles and Talcahuano/Concepción in south-central Chile, in a region where tornado activity is not common. The main goal of this study was to analyze these tornadoes across multiple scales: synoptic, mesoscale, and subseasonal. On the synoptic scale, the tornadoes were associated with an anomalous 500-hPa trough and associated surface cyclone to the west of Chile. A strong (20+ m s−1) low-level jet accompanied this trough, potentially enhanced by flow blocking by the Andes. A relatively warm and saturated surface layer combined with cold upper-level temperatures in the trough to yield 200–500 J kg−1 of CAPE on both days. This CAPE was accompanied by high levels of both deep-layer and low-level shear. Storm motions inferred by lightning swaths and GOES-IR imagery, along with estimates of storm motion and updraft helicity from a high-resolution WRF simulation, suggested this CAPE-shear combination was sufficient for the tornadic thunderstorms to be supercells. Finally, anomalies of sea level pressure, 500-hPa height, and surface dew point temperature from 27 to 31 May 2019 resembled long-term composite anomalies for MJO phases 1 and 2, suggesting a subseasonal link between the extreme event in Chile and convection in the tropics.Atmospheric Research01698095 Reuters ISIsea level, storms, chile, dewpoint temperature, meso-scale modeling, multi scale analysis, sea level pressure, synoptic meteorology, tornadic thunderstorms, upper level temperatures, tornadoes, air temperature, atmospheric convection, cyclone, jet stream, mesoscale meteorology, sea level pressure, synoptic meteorology, thunderstorm, tornado, updraft, andes, bio bio, chile, concepcion [bio bio], los angeles [bio bio], talcahuano
AOT Retrieval Procedure for Distributed Measurements With Low-Cost Sun Photometers: AOT RETRIEVAL METHOD FOR SUN PHOTOMETERSToledo, F.; Garrido, C.; Díaz, M.; Rondanelli, R.; Jorquera, S.; Valdivieso, P.Zonas Costeras2018.010.1002/2017JD027309We propose a new application of inexpensive light-emitting diode (LED)-based Sun photometers, consisting of measuring the aerosol optical thickness (AOT) with high resolution within metropolitan scales. Previously, these instruments have been used at continental scales by the GLOBE program, but this extension is already covered by more expensive and higher-precision instruments of the AERONET global network. For this we built an open source two-channeled LED-based Sun photometer based on previous developments, with improvements in the hardware, software, and modifications on the calibration procedure. Among these we highlight the use of MODTRAN to characterize the effect introduced by using LED sensors in the AOT retrieval, an open design available for the scientific community and a calibration procedure that takes advantage of a CIMEL Sun photometer located within the city, enables the intercomparison of several LED Sun photometers with a common reference. We estimated the root-mean-square error in the AOT retrieved by the prototypes as 0.006 at the 564 nm and 0.009 at the 408 nm. This error is way under the magnitude of the AOT daily cycle variability measured by us in our campaigns, even for distances closer than 15 km. In addition to inner city campaigns, we also show aerosol-tracing applications by measuring AOT variations from the city of Santiago to the Andes glaciers. Measuring AOT at high spatial resolution in urban areas can improve our understanding of urban scale aerosol circulation, providing information for solar energy planning, health policies, and climatological studies, among others.Journal of Geophysical Research: Atmospheres2169-897X Reuters ISIaeronet, aerosol, calibration, electrode, energy planning, glacier, metropolitan area, photometer, solar power, spatial resolution, urban area, andes, chile, metropolitana
Microbial activity during a coastal phytoplankton bloom on the Western Antarctic Peninsula in late summerAlcamán-Arias, María E; Farías, Laura; Verdugo, Josefa; Alarcón-Schumacher, Tomás; Díez, BeatrizZonas Costeras2018.010.1093/femsle/fny090Phytoplankton biomass during the austral summer is influenced by freezing and melting cycles as well as oceanographic processes that enable nutrient redistribution in the West Antarctic Peninsula (WAP). Microbial functional capabilities, metagenomic and metatranscriptomic activities as well as inorganic 13C- and 15N-assimilation rates were studied in the surface waters of Chile Bay during two contrasting summer periods in 2014. Concentrations of Chlorophyll a (Chla) varied from 0.3 mg m−3 in February to a maximum of 2.5 mg m−3 in March, together with a decrease in nutrients; however, nutrients were never depleted. The microbial community composition remained similar throughout both sampling periods; however, microbial abundance and activity changed with Chla levels. An increased biomass of Bacillariophyta, Haptophyceae and Cryptophyceae was observed along with night-grazing activity of Dinophyceae and ciliates (Alveolates). During high Chla conditions, HCO3− uptake rates during daytime incubations increased 5-fold (>2516 nmol C L−1 d−1), and increased photosynthetic transcript numbers that were mainly associated with cryptophytes; meanwhile night time NO3− (>706 nmol N L−1 d−1) and NH4+ (41.7 nmol N L−1 d−1) uptake rates were 2- and 3-fold higher, respectively, due to activity from Alpha-/Gammaproteobacteria and Bacteroidetes (Flavobacteriia). Due to a projected acceleration in climate change in the WAP, this information is valuable for predicting the composition and functional changes in Antarctic microbial communities.FEMS Microbiology Letters1574-6968 Reuters ISIammonia, bicarbonate, carbon 13, chlorophyll a, nitrate, nitrogen 15, surface water, bacterial protein, sea water, algal bloom, alphaproteobacteria, antarctica, bacteroidetes, biomass, carbon fixation, coastal waters, concentration (parameters), cryptophyta, diatom, dinoflagellate, gammaproteobacteria, haptophyta, incubation time, metagenomics, metatranscriptomics, microbial activity, microbial community, nitrogen fixation, nonhuman, omics, population abundance, priority journal, salinity, short survey, species composition, summer, water sampling, water temperature, bacterium, chemistry, classification, ecosystem, eukaryote, genetics, growth, development and aging, metabolism, microbiology, microflora, photosynthesis, phytoplankton, season, antarctic regions, bacteria, bacterial proteins, ecosystem, eukaryota, microbiota, photosynthesis, phytoplankton, seasons, seawater
Foehn Event Triggered by an Atmospheric River Underlies Record-Setting Temperature Along Continental AntarcticaBozkurt, D.; Rondanelli, R.; Marín, J. C.; Garreaud, R.Zonas Costeras; Agua y Extremos; Transversal2018.010.1002/2017JD027796A record‐setting temperature of 17.5°C occurred on 24 March 2015 at the Esperanza station located near the northern tip of the Antarctic Peninsula (AP). We studied the event using surface station data, satellite imagery, reanalysis data, and numerical simulations. The Moderate Resolution Imaging Spectroradiometer Antarctic Ice Shelf Image Archive provides clear evidence for disintegration and advection of sea ice, as well as the formation of melt ponds on the ice sheet surface at the base of the AP mountain range. A deep low‐pressure center over the Amundsen‐Bellingshausen Sea and a blocking ridge over the southeast Pacific provided favorable conditions for the development of an atmospheric river with a northwest‐southeast orientation, directing warm and moist air toward the AP, and triggering a widespread foehn episode. A control simulation using a regional climate model shows the existence of local topographically induced warming along the northern tip of the AP (∼60% of the full temperature signal) and the central part of the eastern AP (>90% of the full temperature signal) with respect to a simulation without topography. These modeling results suggest that more than half of the warming experienced at Esperanza can be attributed to the foehn effect (a local process), rather than to the large‐scale advection of warm air from the midlatitudes. Nevertheless, the local foehn effect also has a large‐scale advection component, since the atmospheric river provides water vapor for orographic precipitation enhancement and latent heat release, which makes it difficult to completely disentangle the role of local versus large‐scale processes in explaining the extreme event.Journal of Geophysical Research: Atmospheres2169-897X Reuters ISIadvection, atmospheric moisture, climate change, climate modeling, extreme event, foehn, high temperature, ice shelf, meteorology, modis, regional climate, temperature, amundsen sea, antarctic peninsula, antarctica, bellingshausen sea, pacific ocean, pacific ocean (southeast), southern ocean, west antarctica, esperanza
Diurnal Changes in Active Carbon and Nitrogen Pathways Along the Temperature Gradient in Porcelana Hot Spring Microbial MatAlcamán-Arias, María E.; Pedrós-Alió, Carlos; Tamames, Javier; Fernández, Camila; Pérez-Pantoja, Danilo; Vásquez, Mónica; Díez, BeatrizZonas Costeras2018.010.3389/fmicb.2018.02353Composition, carbon and nitrogen uptake, and gene transcription of microbial mat communities in Porcelana neutral hot spring (Northern Chilean Patagonia) were analyzed using metagenomics, metatranscriptomics and isotopically labeled carbon ((HCO3)-C-13) and nitrogen ((NH4Cl)-N-15 and (KNO3)-N-15) assimilation rates. The microbial mat community included 31 phyla, of which only Cyanobacteria and Chloroflexi were dominant. At 58 degrees C both phyla co-occurred, with similar contributions in relative abundances in metagenomes and total transcriptional activity. At 66 degrees C, filamentous anoxygenic phototrophic Chloroflexi were >90% responsible for the total transcriptional activity recovered, while Cyanobacteria contributed most metagenomics and metatranscriptomics reads at 48 degrees C. According to such reads, phototrophy was carried out both through oxygenic photosynthesis by Cyanobacteria (mostly Mastigocladus) and anoxygenic phototrophy due mainly to Chloroflexi. Inorganic carbon assimilation through the Calvin-Benson cycle was almost exclusively due to Mastigocladus, which was the main primary producer at lower temperatures. Two other CO2 fixation pathways were active at certain times and temperatures as indicated by transcripts: 3-hydroxypropionate (3-HP) bi-cycle due to Chloroflexi and 3-hydroxypropionate-4-hydroxybutyrate (HH) cycle carried out by Thaumarchaeota. The active transcription of the genes involved in these C-fixation pathways correlated with high in situ determined carbon fixation rates. In situ measurements of ammonia assimilation and nitrogen fixation (exclusively attributed to Cyanobacteria and mostly to Mastigocladus sp.) showed these were the most important nitrogen acquisition pathways at 58 and 48 degrees C. At 66 degrees C ammonia oxidation genes were actively transcribed (mostly due to Thaumarchaeota). Reads indicated that denitrification was present as a nitrogen sink at all temperatures and that dissimilatory nitrate reduction to ammonia (DNRA) contributed very little. The combination of metagenomic and metatranscriptomic analysis with in situ assimilation rates, allowed the reconstruction of day and night carbon and nitrogen assimilation pathways together with the contribution of keystone microorganisms in this natural hot spring microbial mat.Frontiers in Microbiology1664-302X Reuters ISIcarbon and nitrogen assimilation, cyanobacteria, metagenomics, metatranscriptomics, microbial mat, neutral hot spring, photosynthesis
Distribution of dissolved methane and nitrous oxide in Chilean coastal systems of the Magellanic Sub-Antarctic region (50°–55°S)Farías, Laura; Bello, Estrella; Arancibia, Gresel; Fernandez, JosselineZonas Costeras2018.010.1016/j.ecss.2018.10.020Nitrous oxide (N2O) and methane (CH4) are greenhouse gases and active in the depletion of the ozone layer. These gases, originating from both anthropogenic and natural sources, are mainly released to the atmosphere from coastal areas, including continental shelves, estuaries and fjords. Surface distribution of dissolved N2O and CH4 during the austral spring were described within the Magellanic Sub-Antarctic region (50–55°S, Chile) with a coastal area that has a complex system of fjords, channels, gulf and, bays. A narrow range of N2O concentrations were observed from under-saturations (∼65%), as result of freshwater/glacial flow into fjord heads, to slight super-saturations (∼120–150%) in fjord mouths and adjacent marine zones. One exception was Otway Sound, where a penguin colony is situated, with N2O levels of up to 218%. In contrast, CH4 concentrations presented a wide range of saturations between 47.9% and 483%, with a spatial distribution that mainly corresponded to the type of hydrographic/geomorphologic basin; in the southern Patagonian Andes (mostly covered by the southern Ice Fields) CH4 levels varied between 65 and 80% in the marine area, and 180% saturation in the channels and fjords; whereas in the southern Patagonian tableland (Magellan Strait) higher CH4 concentrations, up to 483% saturation, were observed apparently associated with continental inputs (peatland and tundra vegetation). N2O concentrations were positively correlated with salinity and nutrients, indicating that the majority of N2O and nutrients (except silicate) originated from the Sub-Antarctic Water Mass (SAAW), which mixes with N2O-depleated freshwater. However, CH4 concentrations did not correlate with any oceanographic variables, suggesting that they originate from local marine/terrestrial interactions. The Magellanic Sub-Antarctic region acts as a modest source of N2O and CH4, to the atmosphere with effluxes of 6.20 ± 10.13 and 16.88 ± 27.04 μmol m−2 d−1 respectively. Due to climate change and a growth in anthropogenic activities such as salmon farming, future emissions of N2O and CH4 within this remote region remain uncertain.Estuarine, Coastal and Shelf Science0272-7714 Reuters ISIcoastal zone, concentration (composition), dissolved gas, fjord, freshwater, greenhouse gas, methane, nitrous oxide, ozone depletion, saturation, spring (season), subantarctic region, andes, antarctica, australia, chile, magellan strait, otway range, patagonia, victoria [australia], spheniscidae
Seasonal drought effects on the water quality of the Biobío River, Central ChileYevenes, Mariela A.; Figueroa, Ricardo; Parra, OscarZonas Costeras2018.010.1007/s11356-018-1415-6Quantifying the effect of droughts on ecosystem functions is essential to the development of coastal zone and river management under a changing climate. It is widely acknowledged that climate change is increasing the frequency and intensity of droughts, which can affect important ecosystem services, such as the regional supply of clean water. Very little is understood about how droughts affect the water quality of Chilean high flow rivers. This paper intends to investigate the effect of an, recently identified, unprecedented drought in Chile (2010–2015), on the Biobío River water quality, (36°45′–38°49′ S and 71°00′–73°20′ W), Central Chile. This river is one of the largest Chilean rivers and it provides abundant freshwater. Water quality (water temperature, pH, dissolved oxygen, electrical conductivity, biological oxygen demand, total suspended solids, chloride, sodium, nutrients, and trace metals), during the drought (2010–2015), was compared with a pre-drought period (2000–2009) over two reaches (upstream and downstream) of the river. Multivariate analysis and seasonal Mann-Kendall trend analyses and a Theil-Sen estimator were employed to analyze trends and slopes of the reaches. Results indicated a significant decreased trend in total suspended solids and a slightly increasing trend in water temperature and EC, major ions, and trace metals (chrome, lead, iron, and cobalt), mainly in summer and autumn during the drought. The reduced variability upstream suggested that nutrient and metal concentrations were more constant than downstream. The results evidenced, due to the close relationship between river discharge and water quality, a slightly decline of the water quality downstream of the Biobío River during drought period, which could be attenuated in a post-drought period. These results displayed that water quality is vulnerable to reductions in flow, through historical and emerging solutes/contaminants and induced pH mobilization. Consequently, seasonal changes and a progressive reduction of river flow affect the ecosystem functionality in this key Chilean river. The outcomes from this research can be used to improve how low flow conditions and the effects of a reduction in the river volume and discharge are assessed, which is the case under the scenario of more frequent drought periods.Environmental Science and Pollution Research0944-1344, 1614-7499 Reuters ISIclimate change, drought, ecosystem function, ecosystem service, river discharge, river flow, river management, seasonal variation, water quality, water supply, water temperature, biobio river, chile, analysis, chemistry, chile, drought, environmental monitoring, river, season, water pollutant, water quality, chile, droughts, environmental monitoring, rivers, seasons, water pollutants, chemical, water quality
Insight into anthropogenic forcing on coastal upwelling off south-central ChileAguirre, Catalina; García-Loyola, Sebastian; Testa, Giovanni; Silva, Diego; Farias, LauraZonas Costeras2018.010.1525/elementa.314Coastal upwelling systems off the coasts of Peru and Chile are among the most productive marine ecosystems in the world, sustaining a significant percentage of global primary production and fishery yields. Seasonal and interannual variability in these systems has been relatively well documented; however, an understanding of recent trends and the influence of climate change on marine processes such as surface cooling and primary productivity is limited. This study presents evidence that winds favorable to upwelling have increased within the southern boundary of the Humboldt Current System (35°–42°S) in recent decades. This trend is consistent with a poleward movement of the influence of the Southeast Pacific Anticyclone and resembles the spatial pattern projected by Global Circulation Models for warming scenarios. Chlorophyll a levels (from 2002 to present) determined by satellite and field-based time-series observations show a positive trend, mainly in austral spring–summer (December–January–February), potentially explained by observed increments in nutrient flux towards surface waters and photosynthetically active radiation. Both parameters appear to respond to alongshore wind stress and cloud cover in the latitudinal range of 35°S to 42°S. In addition, net annual deepening of the mixed layer depth is estimated using density and temperature profiles. Changes in this depth are associated with increasing winds and may explain cooler, more saline, and more productive surface waters, with the latter potentially causing fluctuations in dissolved oxygen and other gases, such as nitrous oxide, sensitive to changes in oxygenation. We argue that these recent changes represent, at least in part, a regional manifestation of the Anthropocene along the Chilean coast.Elem Sci Anth2325-1026 Reuters ISIannual variation, anthropocene, anthropogenic effect, anticyclone, climate change, cloud cover, coastal zone, cooling, dissolved oxygen, estimation method, marine ecosystem, mixed layer, oxygenation, primary production, satellite data, seasonal variation, upwelling, wind stress, chile, humboldt current, pacific ocean, pacific ocean (southeast), peru
A new method to evaluate the vulnerability of watersheds facing several stressors: A case study in mediterranean ChileArriagada, Loretto; Rojas, Octavio; Arumí, José Luis; Munizaga, Juan; Rojas, Carolina; Farias, Laura; Vega, ClaudioZonas Costeras2019.010.1016/j.scitotenv.2018.09.237Freshwater systems are subjected to multiple anthropogenic stressors and natural disturbances that act as debilitating agents and modifiers of river systems, causing cumulative and synergistic effects that deteriorate their health and result in watershed vulnerability. This study proposes an easy-to-apply spatial method of watershed vulnerability evaluation using Geographic Information Systems (GIS) in the Andalién River watershed, located in the Chilean mediterranean. A watershed vulnerability index (WVI) based on three sub-indices – anthropogenic stressors, environmental fragility and natural disturbances – was developed. To determine the index grouping weights, expert surveys were carried out using the Delphi method. We subsequently normalized and integrated the factors of each sub-index with relative weights. The ranges of each thematic layer were re-classified to establish vulnerability scores. The watershed was divided into three sections: headwaters zone, transfer zone and depositional zone. The watershed vulnerability index showed that 41% of the watershed had very low vulnerability and 42% had medium vulnerability, while only 1% – in the depositional zone – had high vulnerability. A one-way ANOVA was carried out to analyze the vulnerability differences among the three sections of the watershed; it showed significant differences (F (2, 16) = 8.15: p < 0.05). The a posteriori test showed differences between the headwaters and depositional zones (Tukey test, p = 0.005) and between the transfer and depositional zones (Tukey test, p = 0.014). To validate the WVI, water quality was measured at 16 stations in the watershed; there was a significant correlation between vulnerability level and NO2 − levels (r = 0.8; p = 0.87; α = 0.05) and pH (r = 0.8; p = 0.80; α = 0.05). The WVI showed the cumulative effects of multiple stressors in the depositional zone of the watershed. This is the first study to evaluate and validate non-regulated watershed vulnerability with GIS using multiple anthropogenic and natural stressors.Science of The Total Environment0048-9697 Reuters ISIdeposition, geographic information systems, information management, information systems, information use, water quality, anthropogenic stressors, environmental fragility, freshwater systems, integrated management, multiple stressors, natural disturbance, vulnerability evaluations, vulnerability index, watersheds, anthropogenic effect, disturbance, environmental assessment, gis, headwater, integrated approach, vulnerability, watershed, article, chile, controlled study, environmental erosion, environmental impact, geographic information system, landfill, priority journal, spatial analysis, thematic analysis, water analysis, water management, water pollution, water quality, water supply, watershed, andalien river, bio bio, chile
Active Crossfire Between Cyanobacteria and Cyanophages in Phototrophic Mat Communities Within Hot SpringsGuajardo-Leiva, Sergio; Pedrós-Alió, Carlos; Salgado, Oscar; Pinto, Fabián; Díez, BeatrizZonas Costeras2018.010.3389/fmicb.2018.02039Cyanophages are viruses with a wide distribution in aquatic ecosystems, that specifically infect Cyanobacteria. These viruses can be readily isolated from marine and fresh waters environments; however, their presence in cosmopolitan thermophilic phototrophic mats remains largely unknown. This study investigates the morphological diversity (TEM), taxonomic composition (metagenomics), and active infectivity (metatranscriptomics) of viral communities over a thermal gradient in hot spring phototrophic mats from Northern Patagonia (Chile). The mats were dominated (up to 53%) by cosmopolitan thermophilic filamentous true-branching cyanobacteria from the genus Mastigocladus, the associated viral community was predominantly composed of Caudovirales (70%), with most of the active infections driven by cyanophages (up to 90% of Caudovirales transcripts). Metagenomic assembly lead to the first full genome description of a T7-like Thermophilic Cyanophage recovered from a hot spring (Porcelana Hot Spring, Chile), with a temperature of 58°C (TC-CHP58). This could potentially represent a world-wide thermophilic lineage of podoviruses that infect cyanobacteria. In the hot spring, TC-CHP58 was active over a temperature gradient from 48 to 66°C, showing a high population variability represented by 1979 single nucleotide variants (SNVs). TC-CHP58 was associated to the Mastigocladus spp. by CRISPR spacers. Marked differences in metagenomic CRISPR loci number and spacers diversity, as well as SNVs, in the TC-CHP58 proto-spacers at different temperatures, reinforce the theory of co-evolution between natural virus populations and cyanobacterial hosts. Considering the importance of cyanobacteria in hot spring biogeochemical cycles, the description of this new cyanopodovirus lineage may have global implications for the functioning of these extreme ecosystems.Frontiers in Microbiology1664-302X Reuters ISIcrispr associated protein, aquatic environment, article, cyanobacterium, cyanophage, high throughput sequencing, mastigocladus, metagenomics, microbial diversity, nonhuman, phototrophy, phylogeny, rna extraction, rna sequence, single nucleotide polymorphism, thermal spring, transmission electron microscopy
Summer phyto- and bacterioplankton communities during low and high productivity scenarios in the Western Antarctic PeninsulaFuentes, Sebastián; Arroyo, José Ignacio; Rodríguez-Marconi, Susana; Masotti, Italo; Alarcón-Schumacher, Tomás; Polz, Martin F.; Trefault, Nicole; De la Iglesia, Rodrigo; Díez, BeatrizZonas Costeras2018.010.1007/s00300-018-2411-5Phytoplankton blooms taking place during the warm season drive high productivity in Antarctic coastal seawaters. Important temporal and spatial variations exist in productivity patterns, indicating local constraints influencing the phototrophic community. Surface water in Chile Bay (Greenwich Island, South Shetlands) is influenced by freshwater from the melting of sea ice and surrounding glaciers; however, it is not a widely studied system. The phyto- and bacterioplankton communities in Chile Bay were studied over two consecutive summers; during a low productivity period (chlorophyll a < 0.05 mg m−3) and an ascendant phototrophic bloom (chlorophyll a up to 2.38 mg m−3). Microbial communities were analyzed by 16S rRNA—including plastidial—gene sequencing. Diatoms (mainly Thalassiosirales) were the most abundant phytoplankton, particularly during the ascendant bloom. Bacterioplankton in the low productivity period was less diverse and dominated by a few operational taxonomic units (OTUs), related to Colwellia and Pseudoalteromonas. Alpha diversity was higher during the bloom, where several Bacteroidetes taxa absent in the low productivity period were present. Network analysis indicated that phytoplankton relative abundance was correlated with bacterioplankton phylogenetic diversity and the abundance of several bacterial taxa. Hubs—the most connected OTUs in the network—were not the most abundant OTUs and included some poorly described taxa in Antarctica, such as Neptunomonas and Ekhidna. In summary, the results of this study indicate that in Antarctic Peninsula coastal waters, such as Chile Bay, higher bacterioplankton community diversity occurs during a phototrophic bloom. This is likely a result of primary production, providing a source of fresh organic matter to bacterioplankton. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature.Polar Biology0722-4060, 1432-2056 Reuters ISIalgal bloom, bacterioplankton, community composition, genetic analysis, organic matter, phylogenetics, phytoplankton, relative abundance, rna, sea ice, seasonality, seawater, summer, antarctic peninsula, antarctica, chilean margin, pacific ocean, west antarctica, bacillariophyta, bacteria (microorganisms), bacteroidetes, colwellia, neptunomonas, otus, pseudoalteromonas, thalassiosirales
Temporal dynamics of dissolved inorganic nitrogen (DIN) in the aphotic layer of a coastal upwelling system with variable dissolved oxygenFarías, Laura; Faúndez, Juan; Sanhueza-Guevara, SandraZonas Costeras2018.010.1016/j.jmarsys.2018.06.001Dissolved O2 (DO) concentration is critical to determining ecosystem functions such as organic matter respiration, which can favor fixed nitrogen loss and the accumulation of compounds such as NH4+. This dynamic is observed in central Chile's coastal upwelling system (36 °S), which presents seasonally O2 deficient waters and high biological productivity. Temporal dynamics for dissolved inorganic nitrogen (DIN: NO3−, NO2− and NH4+) are analyzed based on a ten year time series of monthly measurements of DO and DIN and a three year record of absolute DIN uptake rates (ρDIN), respective turnover rates (νDIN), and O2 utilization rates (OUR). Observed O2 deficit gradually increases from hypoxia to near anoxia as the system becomes more productive, favoring the accumulation of NO2− and NH4+. Three temporal phases within the aphotic layer were distinguished: (I) DO > 62 μmol L−1 (May to August), (II) 5 < DO < 62 μmol L−1 (September to December) and (III) DO < 5 μmol L−1 (January to April). From phase I to III, DO and NO3− inventories decreased by eight and two times, respectively, while NH4+ and NO2 inventories increased two- and five-fold, respectively. Uptake rates for NH4+ varied from 0.23 to 450 nmol N L−1 d−1 and from 1.42 to 184 nmol N L−1 d−1 for NO3−. Notably, integrated ρNH4+ increased during phase III, generating a NH4+ turnover time of 12–29 days; whereas integrated ρNO3− peaked during phase II, and removed the NO3− pool over an extended turnover time (>820 days). Integrated OUR gradually increased from phase I to III (from 225 to 422 mmol m−2 d−1), with DO pools replenished over 2.3 to 26 days. NH4+ regeneration rates ranged from 34 to 62 mmol m−2 d−1 and NH4+ pools were replenished within a few days. Variation in DO, which regulates N cycling, may explain the accumulation of N-species within the aphotic layer. Observed trends could be extrapolated to scenarios of upwelling-favorable winds, eutrophication and hypoxia.Journal of Marine Systems0924-7963 Reuters ISIcoastal engineering, dissolution, eutrophication, lakes, nitrogen, nitrogen oxides, aphotic layer, biological productivity, coastal upwelling, dissolved inorganic nitrogens, ecosystem functions, oxygen utilization, regeneration rate, temporal dynamics, dissolved oxygen, coastal zone, dissolved inorganic nitrogen, dissolved oxygen, eutrophication, hypoxia, nitrogen cycle, temporal variation, time series analysis, upwelling, chile
Temperature modulates Fischerella thermalis ecotypes in Porcelana Hot SpringAlcorta, Jaime; Espinoza, Sebastián; Viver, Tomeu; Alcamán-Arias, María E.; Trefault, Nicole; Rosselló-Móra, Ramon; Díez, BeatrizZonas Costeras2018.010.1016/j.syapm.2018.05.006Systematic and Applied Microbiology07232020 Reuters ISIallele, article, bacterial genome, bacterial strain, ecotype, fischerella, fischerella thermalis, genetic variability, matrix assisted laser desorption ionization time of flight mass spectrometry, metagenome, nitrogen fixation, nonhuman, photosynthesis, priority journal, proteomics, temperature, temperature acclimatization, thermal spring, thermophilic bacterium, chile, cyanobacterium, genetics, heat, isolation and purification, matrix-assisted laser desorption-ionization mass spectrometry, microbiology, molecular evolution, phylogeny, thermal spring, bacterial dna, proteome, rna 16s, chile, cyanobacteria, dna, bacterial, ecotype, evolution, molecular, hot springs, hot temperature, metagenome, phylogeny, proteome, rna, ribosomal, 16s, spectrometry, mass, matrix-assisted laser desorption-ionization
Bacterial community structure in a sympagic habitat expanding with global warming: brackish ice brine at 85–90 °NFernández-Gómez, Beatriz; Díez, Beatriz; Polz, Martin F.; Arroyo, José Ignacio; Alfaro, Fernando D.; Marchandon, Germán; Sanhueza, Cynthia; Farías, Laura; Trefault, Nicole; Marquet, Pablo A.; Molina-Montenegro, Marco A.; Sylvander, Peter; Snoeijs-Leijonmalm, PaulineZonas Costeras2018.010.1038/s41396-018-0268-9Larger volumes of sea ice have been thawing in the Central Arctic Ocean (CAO) during the last decades than during the past 800,000 years. Brackish brine (fed by meltwater inside the ice) is an expanding sympagic habitat in summer all over the CAO. We report for the first time the structure of bacterial communities in this brine. They are composed of psychrophilic extremophiles, many of them related to phylotypes known from Arctic and Antarctic regions. Community structure displayed strong habitat segregation between brackish ice brine (IB; salinity 2.4–9.6) and immediate sub-ice seawater (SW; salinity 33.3–34.9), expressed at all taxonomic levels (class to genus), by dominant phylotypes as well as by the rare biosphere, and with specialists dominating IB and generalists SW. The dominant phylotypes in IB were related to Candidatus Aquiluna and Flavobacterium, those in SW to Balneatrix and ZD0405, and those shared between the habitats to Halomonas, Polaribacter and Shewanella. A meta-analysis for the oligotrophic CAO showed a pattern with Flavobacteriia dominating in melt ponds, Flavobacteriia and Gammaproteobacteria in solid ice cores, Flavobacteriia, Gamma- and Betaproteobacteria, and Actinobacteria in brine, and Alphaproteobacteria in SW. Based on our results, we expect that the roles of Actinobacteria and Betaproteobacteria in the CAO will increase with global warming owing to the increased production of meltwater in summer. IB contained three times more phylotypes than SW and may act as an insurance reservoir for bacterial diversity that can act as a recruitment base when environmental conditions change.The ISME Journal1751-7362 Reuters ISIbacterium, brackish water, brine, community structure, dominance, environmental conditions, extremophile, generalist, global warming, meltwater, oligotrophic environment, sea ice, seawater, specialist, arctic and antarctic, arctic ocean, actinobacteria, alphaproteobacteria, bacteria (microorganisms), balneatrix, betaproteobacteria, flavobacterium, gammaproteobacteria, halomonas, polaribacter, shewanella, sea water, actinobacteria, alphaproteobacteria, antarctica, arctic, bacterium, classification, ecosystem, flavobacteriaceae, gammaproteobacteria, greenhouse effect, ice cover, isolation and purification, microbiology, salinity, season, actinobacteria, alphaproteobacteria, antarctic regions, arctic regions, bacteria, ecosystem, flavobacteriaceae, gammaproteobacteria, global warming, ice cover, salinity, seasons, seawater
Plankton composition, biomass, phylogeny and toxin genes in Lake Big Momela, TanzaniaHamisi, Mi; Lugomela, C; Lyimo, Tj; Bergman, B; Díez, BZonas Costeras2017.010.2989/16085914.2017.1334621Lake Big Momela, one of the East African soda lakes in Northern Tanzania characterised by highly saline-alkaline conditions, making them inhospitable to a range of organisms, although supporting massive growths of some adapted planktonic microorganisms that serve as food for birds, such as Lesser Flamingo. The temporal dynamics of plankton, with an emphasis on cyanobacteria, were examined in 2007 using morphological traits and ribosomal genetic markers (16S and 18S rRNA). Cyanobacterial genes encoding for hepatotoxins (mcyE and ndaF) were also screened. Rotifers and copepods dominated the zooplankton, whereas cyanobacteria, such as Anabaenopsis elenkinii and Arthrospira fusiformis dominated the phytoplankton community, and these being related to representatives in other East African soda lakes. The cyanobacteria community also showed distinct seasonal patterns influenced by environmental parameters, mainly salinity, pH and nitrate. Significant positive correlations were found between phytoplankton abundance and nitrate concentrations (r = 0.617, p = 0.033). No signals of the hepatotoxin synthetase genes mcyE and ndaF were retrieved from cyanobacteria during the whole year. In general, our data illustrate the presence of rich planktonic communities, including some unique and potentially endemic cyanobacteria.African Journal of Aquatic Science1608-5914, 1727-9364 Reuters ISIcyanotoxin, limnology, plankton diversity, soda lakes
Implementation of methane cycling for deep-time global warming simulations with the DCESS Earth system model (version 1.2)Shaffer, Gary; Fernández Villanueva, Esteban; Rondanelli, Roberto; Pedersen, Jens Olaf Pepke; Olsen, Steffen Malskær; Huber, MatthewZonas Costeras2017.010.5194/gmd-10-4081-2017Geological records reveal a number of ancient, large and rapid negative excursions of the carbon-13 isotope. Such excursions can only be explained by massive injections of depleted carbon to the Earth system over a short duration. These injections may have forced strong global warming events, sometimes accompanied by mass extinctions such as the Triassic-Jurassic and end-Permian extinctions 201 and 252 million years ago, respectively. In many cases, evidence points to methane as the dominant form of injected carbon, whether as thermogenic methane formed by magma intrusions through overlying carbon-rich sediment or from warming-induced dissociation of methane hydrate, a solid compound of methane and water found in ocean sediments. As a consequence of the ubiquity and importance of methane in major Earth events, Earth system models for addressing such events should include a comprehensive treatment of methane cycling but such a treatment has often been lacking. Here we implement methane cycling in the Danish Center for Earth System Science (DCESS) model, a simplified but well-tested Earth system model of intermediate complexity. We use a generic methane input function that allows variation in input type, size, timescale and ocean–atmosphere partition. To be able to treat such massive inputs more correctly, we extend the model to deal with ocean suboxic/anoxic conditions and with radiative forcing and methane lifetimes appropriate for high atmospheric methane concentrations. With this new model version, we carried out an extensive set of simulations for methane inputs of various sizes, timescales and ocean–atmosphere partitions to probe model behavior. We find that larger methane inputs over shorter timescales with more methane dissolving in the ocean lead to ever-increasing ocean anoxia with consequences for ocean life and global carbon cycling. Greater methane input directly to the atmosphere leads to more warming and, for example, greater carbon dioxide release from land soils. Analysis of synthetic sediment cores from the simulations provides guidelines for the interpretation of real sediment cores spanning the warming events. With this improved DCESS model version and paleo-reconstructions, we are now better armed to gauge the amounts, types, timescales and locations of methane injections driving specific, observed deep-time, global warming events.Geoscientific Model Development1991-9603 Reuters ISIair-sea interaction, anoxic conditions, carbon cycle, carbon dioxide, carbon isotope, climate modeling, extinction, global warming, jurassic, marine sediment, methane, permian, radiative forcing, sediment core, simulation, suboxic conditions, terrestrial environment, triassic, denmark
A solar radiation database for ChileMolina, Alejandra; Falvey, Mark; Rondanelli, RobertoZonas Costeras2017.010.1038/s41598-017-13761-xChile hosts some of the sunniest places on earth, which has led to a growing solar energy industry in recent years. However, the lack of high resolution measurements of solar irradiance becomes a critical obstacle for both financing and design of solar installations. Besides the Atacama Desert, Chile displays a large array of "solar climates" due to large latitude and altitude variations, and so provides a useful testbed for the development of solar irradiance maps. Here a new public database for surface solar irradiance over Chile is presented. This database includes hourly irradiance from 2004 to 2016 at 90 m horizontal resolution over continental Chile. Our results are based on global reanalysis data to force a radiative transfer model for clear sky solar irradiance and an empirical model based on geostationary satellite data for cloudy conditions. The results have been validated using 140 surface solar irradiance stations throughout the country. Model mean percentage error in hourly time series of global horizontal irradiance is only 0.73%, considering both clear and cloudy days. The simplicity and accuracy of the model over a wide range of solar conditions provides confidence that the model can be easily generalized to other regions of the world.Scientific Reports2045-2322 Reuters ISIchile, solar radiation, time series analysis, article
Vertical segregation among pathways mediating nitrogen loss (N2 and N2O production) across the oxygen gradient in a coastal upwelling ecosystemGalán, Alexander; Thamdrup, Bo; Saldías, Gonzalo S.; Farías, LauraZonas Costeras2017.010.5194/bg-14-4795-2017The upwelling system off central Chile (36.5 S) is seasonally subjected to oxygen (O2)-deficient waters, with a strong vertical gradient in O2 (from oxic to anoxic conditions) that spans a few metres (30-50€m interval) over the shelf. This condition inhibits and/or stimulates processes involved in nitrogen (N) removal (e.g. anammox, denitrification, and nitrification). During austral spring (September 2013) and summer (January 2014), the main pathways involved in N loss and its speciation, in the form of N2 and/or N2O, were studied using 15N-tracer incubations, inhibitor assays, and the natural abundance of nitrate isotopes along with hydrographic information. Incubations were developed using water retrieved from the oxycline (25€m depth) and bottom waters (85€m depth) over the continental shelf off Concepción, Chile. Results of 15N-labelled incubations revealed higher N removal activity during the austral summer, with denitrification as the dominant N2-producing pathway, which occurred together with anammox at all times. Interestingly, in both spring and summer maximum potential N removal rates were observed in the oxycline, where a greater availability of oxygen was observed (maximum O2 fluctuation between 270 and 40€μmol€L'1) relative to the hypoxic bottom waters ( < €20€μmol€O2€L'1). Different pathways were responsible for N2O produced in the oxycline and bottom waters, with ammonium oxidation and dissimilatory nitrite reduction, respectively, as the main source processes. Ammonium produced by dissimilatory nitrite reduction to ammonium (DNiRA) could sustain both anammox and nitrification rates, including the ammonium utilized for N2O production. The temporal and vertical variability of /15N-NO3' confirms that multiple N-cycling processes are modulating the isotopic nitrate composition over the shelf off central Chile during spring and summer. N removal processes in this coastal system appear to be related to the availability and distribution of oxygen and particles, which are a source of organic matter and the fuel for the production of other electron donors (i.e. ammonium) and acceptors (i.e. nitrate and nitrite) after its remineralization. These results highlight the links between several pathways involved in N loss. They also establish that different mechanisms supported by alternative N substrates are responsible for substantial accumulation of N2O, which are frequently observed as hotspots in the oxycline and bottom waters. Considering the extreme variation in oxygen observed in several coastal upwelling systems, these findings could help to understand the ecological and biogeochemical implications due to global warming where intensification and/or expansion of the oceanic OMZs is projected.Biogeosciences1726-4189 Reuters ISIbioassay, biogeochemical cycle, bottom water, continental shelf, denitrification, ecosystem dynamics, environmental gradient, global warming, nitrogen, nitrogen cycle, organic matter, oxygen, oxygen minimum layer, tracer, upwelling, vertical profile, chile
Automated Low-Cost LED-Based Sun Photometer for City Scale Distributed MeasurementsGarrido, Cristobal; Toledo, Felipe; Diaz, Marcos; Rondanelli, RobertoZonas Costeras2021.010.3390/rs13224585We propose a monochromatic low-cost automatic sun photometer (LoCo-ASP) to perform distributed aerosol optical depth (AOD) measurements at the city scale. This kind of network could fill the gap between current automatic ground instruments—with good temporal resolution and accuracy, but few devices per city and satellite products—with global coverage, but lower temporal resolution and accuracy-. As a first approach, we consider a single equivalent wavelength around 408 nm. The cost of materials for the instrument is around 220 dollars. Moreover, we propose a calibration transfer for a pattern instrument, and estimate the uncertainties for several units and due to the internal differences and the calibration process. We achieve a max MAE of 0.026 for 38 sensors at 408 nm compared with AERONET Cimel; a mean standard deviation of 0.0062 among our entire sensor for measurement and a calibration uncertainty of 0.01. Finally, we perform city-scale measurements to show the dynamics of AOD. Our instrument can measure unsupervised, with an expected error for AOD between 0.02 and 0.03.Remote Sensing2072-4292 Reuters ISIaerosols, calibration, costs, optical properties, photometers, photometry, uncertainty analysis, aerosol optical depths, city scale, distributed aerosol, distributed measurements, led-based sun photometer, low-costs, monochromatics, network measurement, sun photometers, temporal resolution, light emitting diodes
Proteorhodopsin Phototrophy in Antarctic Coastal WatersCifuentes-Anticevic, Jerónimo; Alcamán-Arias, María E.; Alarcón-Schumacher, Tomás; Tamayo-Leiva, Javier; Pedrós-Alió, Carlos; Farías, Laura; Díez, BeatrizZonas Costeras2021.010.1128/mSphere.00525-21Proteorhodopsin-bearing microorganisms in the Southern Ocean have been overlooked since their discovery in 2000. The present study identify taxonomy and quantify the relative abundance of proteorhodopsin-bearing bacteria and proteorhodopsin gene transcription in the West Antarctic Peninsula’s coastal waters. , ABSTRACT Microbial proton-pumping rhodopsins are considered the simplest strategy among phototrophs to conserve energy from light. Proteorhodopsins are the most studied rhodopsins thus far because of their ubiquitous presence in the ocean, except in Antarctica, where they remain understudied. We analyzed proteorhodopsin abundance and transcriptional activity in the Western Antarctic coastal seawaters. Combining quantitative PCR (qPCR) and metagenomics, the relative abundance of proteorhodopsin-bearing bacteria accounted on average for 17, 3.5, and 29.7% of the bacterial community in Chile Bay (South Shetland Islands) during 2014, 2016, and 2017 summer-autumn, respectively. The abundance of proteorhodopsin-bearing bacteria changed in relation to environmental conditions such as chlorophyll a and temperature. Alphaproteobacteria , Gammaproteobacteria , and Flavobacteriia were the main bacteria that transcribed the proteorhodopsin gene during day and night. Although green light-absorbing proteorhodopsin genes were more abundant than blue-absorbing ones, the latter were transcribed more intensely, resulting in >50% of the proteorhodopsin transcripts during the day and night. Flavobacteriia were the most abundant proteorhodopsin-bearing bacteria in the metagenomes; however, Alphaproteobacteria and Gammaproteobacteria were more represented in the metatranscriptomes, with qPCR quantification suggesting the dominance of the active SAR11 clade. Our results show that proteorhodopsin-bearing bacteria are prevalent in Antarctic coastal waters in late austral summer and early autumn, and their ecological relevance needs to be elucidated to better understand how sunlight energy is used in this marine ecosystem. IMPORTANCE Proteorhodopsin-bearing microorganisms in the Southern Ocean have been overlooked since their discovery in 2000. The present study identify taxonomy and quantify the relative abundance of proteorhodopsin-bearing bacteria and proteorhodopsin gene transcription in the West Antarctic Peninsula’s coastal waters. This information is crucial to understand better how sunlight enters this marine environment through alternative ways unrelated to chlorophyll-based strategies. The relative abundance of proteorhodopsin-bearing bacteria seems to be related to environmental parameters (e.g., chlorophyll a , temperature) that change yearly at the coastal water of the West Antarctic Peninsula during the austral late summers and early autumns. Proteorhodopsin-bearing bacteria from Antarctic coastal waters are potentially able to exploit both the green and blue spectrum of sunlight and are a prevalent group during the summer in this polar environment.mSphere2379-5042 Reuters ISIchlorophyll a, proteorhodopsin, rhodopsin, unclassified drug, alphaproteobacteria, antarctica, article, autumn, coastal waters, flavobacteria, gammaproteobacteria, genetic transcription, metagenome, microbial community, nonhuman, population abundance, proteorhodopsin gene, summer, temperature
Ecogenomics and Adaptation Strategies of Southern Ocean Viral CommunitiesAlarcón-Schumacher, Tomás; Guajardo-Leiva, Sergio; Martinez-Garcia, Manuel; Díez, BeatrizZonas Costeras2021.010.1128/mSystems.00396-21Viruses 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.mSystems2379-5077 Reuters ISImolecular and physiological adaptations, southern ocean, stress adaptation, viral diversity