Línea de investigación:

Zona costera

Aunque representa solo el 10% de la superficie del océano, la zona costera alberga el 90% de todas las especies marinas y presenta dinámicas capaces de modular el clima regional y generar efectos globales. Las principales ciudades chilenas están ubicadas en esta área y se ven cada vez más expuestas a los impactos del cambio climático. Para el (CR)2, la investigación en la zona costera aborda la influencia de la variabilidad climática y el forzamiento antropogénico en el océano y el fondo marino costeros en zonas clave de surgencia en Chile, así como en los sistemas socioecológicos contenidos.

El fenómeno de surgencia costera (ascenso de aguas profundas ricas en nutrientes) favorece el desarrollo de la industria pesquera en nuestro país. Evaluar los riesgos e impactos asociados a esta actividad requerirá una mejor observación y modelado por parte de nuestros investigadores, así como el diseño y la implementación de acciones de adaptación y mitigación.

Las floraciones microalgales, la eutrofización, así como la mayor incidencia de tormentas y marejadas plantean nuevos desafíos para la gobernanza en las costas chilenas. La regulación en esta zona es diversa y compleja, lo que genera problemas institucionales que deben abordarse desde la línea de investigación.

Las proyecciones climáticas para Chile indican cambios que los regímenes de vientos regionales que favorecerán la surgencia costera. Además, se espera que la disponibilidad de agua dulce se vea afectada por los cambios en los sistemas de precipitación. Estas tendencias pueden afectar el flujo de calor, los aerosoles y la concentración de gases en la costa chilena, entre otros impactos. Por esta razón, los esfuerzos de la línea de investigación se centrarán en el forzamiento climático actual para comprender los procesos que pueden tener implicaciones climáticas, como las modificaciones en la advección o la circulación estuarina.

INVESTIGADORA PRINCIPAL

CO-INVESTIGADOR PRINCIPAL

INVESTIGADORES ASOCIADOS

INVESTIGADORES ADJUNTOS

INVESTIGADORES POSTDOCTORALES

ESTUDIANTES

Nombre Apellido
Felipe Andrés Vargas Goméz
Patricio Morales Pacheco
Catalina Barra
María del Pilar Aparicio Rizzo
Maura Francisca Araneda Silva
María José Araya Lobos
Myriam Macarena Troncoso
Sergio Guajardo Leiva
Angeline González
José Ignacio Arroyo González
Felipe Toledo
Giovanni Testa
Maximo Quezada
Pablo Ignacio Garrido Darricarrere
Cristóbal Garrido
Sandy Elizabeth Tenorio Sanchéz
Javier Alejandro Ignacio Tamayo Leiva
Diego Campos
Flor Uribe Ruiz
Susana Rodríguez Marconi
Valeria Moreno
Diego Andrés Silva Díaz
Francisca Clemo
Mirko del Hoyo
Amanda Valencia

Noticias relacionadas a esta línea

Línea de InvestigaciónAñoAutoresTítuloRevistaFicha de PublicaciónDOIAbstractAccesoPáginasVolumenIndex
Zonas Costeras2017Galán, A., Thamdrup, B., Saldías, G. S., Farías, L.Vertical segregation among pathways mediating nitrogen loss (N2 and N2O production) across the oxygen gradient in a coastal upwelling ecosystemBiogeosciences10.5194/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.https://www.biogeosciences.net/14/4795/2017/4795-4813vol.14Thomson Reuters ISI
Zonas Costeras2017Hamisi, Mi., Lugomela, C., Lyimo, Tj., Bergman, B., Díez, B.Plankton composition, biomass, phylogeny and toxin genes in Lake Big Momela, TanzaniaAfrican Journal of Aquatic Science10.2989/16085914.2017.1334621
Lake 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.https://www.tandfonline.com/doi/full/10.2989/16085914.2017.1334621109-121vol.42Thomson Reuters ISI
Zonas Costeras2017Molina, A., Falvey, M., Rondanelli, R.A solar radiation database for ChileScientific Reports10.1038/s41598-017-13761-x
Chile 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.http://www.nature.com/articles/s41598-017-13761-xvol.7Thomson Reuters ISI
Zonas Costeras2017Shaffer, G., Fernández Villanueva, E., Rondanelli, R., Pedersen, J. O. P., Olsen, S. M., Huber, M.
Implementation of methane cycling for deep time, global warming simulations with the DCESS Earth System Model (Version 1.2)
Geoscientific Model Development
10.5194/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.https://www.geosci-model-dev.net/10/4081/2017/4081-4103vol.10 is.11Thomson Reuters ISI
Zonas Costeras2017Toledo, F., Rodriguez, R., Rondanelli, R., Aguirre, R., Diaz, M.SDR Cloud Radar development with reused radio telescope componentsIEEE Geoscience and Remote Sensing10.1109/GRSS-CHILE.2017.7996016The ongoing implementation of a fog observatory in a coastal fog forest in northern Chile is expected to provide valuable information to improve our comprehension of these ecosystems alongside retrieving valuable data to fog scientists. Observing this opportunity and the increase on radio astronomy instrumental it is proposed to develop a low-cost Cloud Radar reutilizing obsolete but operative radio telescope components and software defined radios for modulation. Only preliminary tests have been conducted so far to test the viability of this approach. These tests show that it is in fact possible to build an emitter and receiver operating at 35 GHz using radio telescope components as a Radio Frequency front-end, and that the detected echo coming from the signal is affected by the presence of liquid water droplets in the air. Further development is being carried on the prototype to enable the detection of fog droplets in the boundary layer up to 2 km of height.http://ieeexplore.ieee.org/document/7996016/01/05/18vol.published onlineNot indexed
Zonas Costeras2018Alcamán-Arias, M.E., Pedrós-Alió, C., Tamames, J., Fernández, C., Pérez-Pantoja, D., Vásquez, M., Díez, B.Frontiers in Microbiology10.3389/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.https://www.frontiersin.org/article/10.3389/fmicb.2018.02353/fullVol.9Thomson Reuters ISI
Zonas Costeras2018Aguirre, C, García-Loyola, S, Testa, G, Silva, D, Farías, L.Insight into anthropogenic forcing on coastal upwelling off south-central ChileElem Sci Anth10.1525/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.https://www.elementascience.org/article/10.1525/elementa.314/593-605Vol.6 is.1Thomson Reuters ISI
Zonas Costeras2018Alcamán-Arias, M., Farías, L., Verdugo, J., Alarcón-Schumacher, T., Díez, B.
Microbial activity during a coastal phytoplankton bloom on the Western Antarctic Peninsula in late summerFEMS Microbiology Letters10.1093/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.https://academic.oup.com/femsle/article/doi/10.1093/femsle/fny090/49611371574-6968vol.365 is.10Thomson Reuters ISI
Zonas Costeras2018Alcorta, J., Espinoza, S., Viver, T., Alcamán-Arias, M., Trefault, N., Rosselló-Móra, R., Díez, B.
Temperature modulates Fischerella thermalis ecotypes in Porcelana Hot Spring
Systematic and Applied Microbiology
10.1016/j.syapm.2018.05.006
In the Porcelana Hot Spring (Northern Patagonia), true-branching cyanobacteria are the dominant primary producers in microbial mats, and they are mainly responsible for carbon and nitrogen fixation. However, little is known about their metabolic and genomic adaptations at high temperatures. Therefore, in this study, a total of 81 Fischerella thermalis strains (also known as Mastigocladus laminosus) were isolated from mat samples in a thermal gradient between 61–46 °C. The complementary use of proteomic comparisons from these strains, and comparative genomics of F. thermalis pangenomes, suggested that at least two different ecotypes were present within these populations. MALDI-TOF MS analysis separated the strains into three clusters; two with strains obtained from mats within the upper temperature range (61 and 54 °C), and a third obtained from mats within the lower temperature range (51 and 46 °C). Both groups possessed different but synonymous nifH alleles. The main proteomic differences were associated with the abundance of photosynthesis-related proteins. Three F. thermalis metagenome assembled genomes (MAGs) were described from 66, 58 and 48 °C metagenomes. These pangenomes indicated a divergence of orthologous genes and a high abundance of exclusive genes at 66 °C. These results improved the current understanding of thermal adaptation of F. thermalis and the evolution of these thermophilic cyanobacterial species.https://linkinghub.elsevier.com/retrieve/pii/S0723202018302297Thomson Reuters ISI
Zonas Costeras2018Arriagada, L., Rojas, O., Arumí, J. L., Munizaga, J., Rojas, C., Farias, L., Vega, C.A new method to evaluate the vulnerability of watersheds facing several stressors: A case study in mediterranean ChileScience of The Total Environment10.1016/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.https://linkinghub.elsevier.com/retrieve/pii/S00489697183368171517-1533vol.651Thomson Reuters ISI
Agua y Extremos; Zonas Costeras; Transversal
2018Bozkurt, D., Rondanelli, R., Marín, J. C., Garreaud, R.
Foehn Event Triggered by an Atmospheric River Underlies Record-Setting Temperature Along Continental AntarcticaJournal of Geophysical Research: Atmospheres10.1002/2017JD027796A 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.http://doi.wiley.com/10.1002/2017JD0277963871-3892vol.123 is.8Thomson Reuters ISI
Zonas Costeras2018Dätwyler Ch., Neukom R., Abram N., Gallant A., Grosjean M., Jacques-Coper M., Karoly D., Villalba R.
Teleconnection stationarity, variability and trends of the Southern Annular Mode (SAM) during the last millenniumClimate Dynamics10.1007/s00382-017-4015-0The Southern Annular Mode (SAM) is the leading mode of atmospheric interannual variability in the Southern Hemisphere (SH) extra-tropics. Here, we assess the stationarity of SAM spatial correlations with instrumental and paleoclimate proxy data for the past millennium. The instrumental period shows that temporal non-stationarities in SAM teleconnections are
not consistent across the SH land areas. This suggests that the influence of the SAM index is modulated by regional effects.
However, within key-regions with good proxy data coverage (South America, Tasmania, New Zealand), teleconnections are mostly stationary over the instrumental period. Using different stationarity criteria for proxy record selection, we provide
new austral summer and annual mean SAM index reconstructions over the last millennium. Our summer SAM reconstructions are very robust to changes in proxy record selection and the selection of the calibration period, particularly on the multi-decadal timescale. In contrast, the weaker performance and lower agreement in the annual mean SAM reconstructions
point towards changing teleconnection patterns that may be particularly important outside the summer months. Our results clearly portend that the temporal stationarity of the proxy-climate relationships should be taken into account in the design of comprehensive regional and hemispherical climate reconstructions. The summer SAM reconstructions show no significant relationship to solar, greenhouse gas and volcanic forcing, with the exception of an extremely strong negative anomaly following the AD 1257 Samalas eruption. Furthermore, reconstructed pre-industrial summer SAM trends are very similar to
trends obtained by model control simulations. We find that recent trends in the summer SAM lie outside the 5–95% range of pre-industrial natural variability.
http://link.springer.com/10.1007/s00382-017-4015-01-19Thomson Reuters ISI
Zonas Costeras2018Farías L., Bello E., Arancibia G., Fernandez J.Distribution of dissolved methane and nitrous oxide in Chilean coastal systems of the Magellanic Sub-Antarctic region (50°–55°S)Estuarine, Coastal and Shelf Science10.1016/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.https://linkinghub.elsevier.com/retrieve/pii/S0272771418304785229-240Vol.215Thomson Reuters ISI
Zonas Costeras2018Farías, L., Faúndez, J., Sanhueza-Guevara, S.Temporal dynamics of dissolved inorganic nitrogen (DIN) in the aphotic layer of a coastal upwelling system with variable dissolved oxygenJournal of Marine Systems10.1016/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.https://linkinghub.elsevier.com/retrieve/pii/S0924796317302075Thomson Reuters ISI
Zonas Costeras2018Fernández-Gómez, B., Díez, B., Polz, M. F., Arroyo, J. I., Alfaro, F. D., Marchandon, G., Sanhueza, C., Farías, L., Trefault, N., Marquet, P. A., Molina-Montenegro, M. A., Sylvander, P., Snoeijs-Leijonmalm, P.Bacterial community structure in a sympagic habitat expanding with global warming: brackish ice brine at 85–90 °NThe ISME Journal10.1038/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.http://www.nature.com/articles/s41396-018-0268-9Thomson Reuters ISI
Zonas Costeras2018Fuentes, S., Arroyo, J.I., Rodríguez-Marconi, S., Masotti, I., Alarcón-Schumacher, T., Polz, M.F., Trefault, N., de la Iglesia, R., Díez, B.Summer phyto- and bacterioplankton communities during low and high productivity scenarios in the Western Antarctic PeninsulaPolar Biology10.1007/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.http://link.springer.com/10.1007/s00300-018-2411-5Thomson Reuters ISI
Zonas Costeras2018Guajardo-Leiva, S., Pedrós-Alió, C., Salgado, O., Pinto, F., Díez, B.Active Crossfire Between Cyanobacteria and Cyanophages in Phototrophic Mat Communities Within Hot SpringsFrontiers in Microbiology10.3389/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.https://www.frontiersin.org/article/10.3389/fmicb.2018.02039/fullvol.9Thomson Reuters ISI
Zonas Costeras2018Sepulveda-Jauregui, A., Martinez-Cruz, K., Lau, M., Casper, P.Assessment of methane and carbon dioxide emissions in two sub-basins of a small acidic bog lake artificially divided 30 years agoFreshwater Biology10.1111/fwb.13182Although lakes are important sources of methane (CH4) and carbon dioxide (CO2) to the atmosphere contributing to global warming, their CH4 and CO2 emissions are rarely assessed. In particular, increasing inputs of terrestrial dissolved organic carbon (DOC) may affect gas dynamics and alter seasonal changes in gas production. Here, we analysed variations in CH4 and CO2 dynamics in sub-basins of an acidic bog lake, which was artificially divided into four quarters three decades ago, leading to divergence in water chemistry and biology. In the divided lake, only the south-west basin (SW) received DOC inputs from an adjacent peat bog, while the north-east basin (NE) was hydrologically disconnected. A year-long determination of CH4 and CO2 production and emission patterns in the two contrasting basins exposed the indirect mechanisms by which DOC supply exercised control on greenhouse gas dynamics in this shallow lake. In both basins, dissolved CH4 was negatively correlated with dissolved oxygen (O2) through the water column, suggesting that aerobic methanotrophy is an important regulator of CH4 emissions in this lake. In contrast, the amount of CO2 stored in oxic and anoxic layers was not significantly different between the basins, suggesting that O2 is not the most important driver of dissolved CO2. Estimated total CH4 and CO2 emissions were 2.1 and 1.7 times lower in the NE basin than in the SW basin, with major CH4 and CO2 emissions occurring during the fall turnover. The differences in CH4 and CO2 emissions suggest that the hydro-physical properties, namely seasonal temperature, the duration of stratification and O2 availability, are the main drivers of CH4 and CO2 emissions to the atmosphere from small shallow lakes under the influence of DOC inputs under global warming pressure.http://doi.wiley.com/10.1111/fwb.13182Thomson Reuters ISI
Zonas Costeras2018Testa, G., Masotti, I., Farías, L.Temporal Variability in Net Primary Production in an Upwelling Area off Central Chile (36°S)Frontiers in Marine Science10.3389/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.https://www.frontiersin.org/article/10.3389/fmars.2018.00179/fullvol.5Scopus
Zonas Costeras2018Toledo, F., Garrido, C., Díaz, M., Rondanelli, R., Jorquera, S., Valdivieso, P.AOT Retrieval Procedure for Distributed Measurements With Low-Cost Sun Photometers: AOT RETRIEVAL METHOD FOR SUN PHOTOMETERSJournal of Geophysical Research: Atmospheres10.1002/2017JD027309We 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.http://doi.wiley.com/10.1002/2017JD0273091113-1131vol.123 is.2Thomson Reuters ISI
Zonas Costeras2018Troncoso, M., Garcia, G., Verdugo, J., Farías, L.Toward High-Resolution Vertical Measurements of Dissolved Greenhouse Gases (Nitrous Oxide and Methane) and Nutrients in the Eastern South PacificFrontiers in Marine Science10.3389/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 (NO3- and PO43-) 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.
https://www.frontiersin.org/article/10.3389/fmars.2018.00148148vol.5Scopus
Zonas Costeras2019Wilson,ST.,Bange ,H.W, Arévalo-Martínez,D.L. ,Barnes, J, Borges, A.V, Brown, I, Bullister,JohnL, Burgos,M, Capelle,D.W., Casso, M, De la Paz, M, Farías, L, Fenwick,L, Ferrón,S,Garcia, G, Glockzin, M, Karl, D.M, Kock,A, Laperriere,S, Law, C.S, Manning,C.C, Marriner,A, Myllykangas,J-P., Pohlman,J.W., Rees, A.P, Santoro,A.E, Torres, M, Tortell, PD, Upstill-Goddard,R.C,.Wisegarver, D.P, Zhang,G.L, Rehder, G.An intercomparison of oceanic methane and nitrous oxide measurementsBiogeosciences10.5194/bg-15-5891-2018Large-scale climatic forcing is impacting oceanic biogeochemical cycles and is expected to influence the water-column distribution of trace gases, including methane and nitrous oxide. Our ability as a scientific community to evaluate changes in the water-column inventories of methane and nitrous oxide depends largely on our capacity to obtain robust and accurate concentration measurements that can be validated across different laboratory groups. This study represents the first formal international intercomparison of oceanic methane and nitrous oxide measurements whereby participating laboratories received batches of seawater samples from the subtropical Pacific Ocean and the Baltic Sea. Additionally, compressed gas standards from the same calibration scale were distributed to the majority of participating laboratories to improve the analytical accuracy of the gas measurements. The computations used by each laboratory to derive the dissolved gas concentrations were also evaluated for inconsistencies (e.g., pressure and temperature corrections, solubility constants). The results from the intercomparison and intercalibration provided invaluable insights into methane and nitrous oxide measurements. It was observed that analyses of seawater samples with the lowest concentrations of methane and nitrous oxide had the lowest precisions. In comparison, while the analytical precision for samples with the highest concentrations of trace gases was better, the variability between the different laboratories was higher: 36% for methane and 27% for nitrous oxide. In addition, the comparison of different batches of seawater samples with methane and nitrous oxide concentrations that ranged over an order of magnitude revealed the ramifications of different calibration procedures for each trace gas. Finally, this study builds upon the intercomparison results to develop recommendations for improving oceanic methane and nitrous oxide measurements, with the aim of precluding future analytical discrepancies between laboratories.https://www.biogeosciences.net/15/5891/2018/5891-5907Vol.15 is.19Thomson Reuters ISI
Zonas Costeras2018Yevenes, MA., Figueroa, R., Parra., O
Seasonal drought effects on the water quality of the Biobío River, Central Chile
Environmental Science and Pollution Research10.1007/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.http://link.springer.com/10.1007/s11356-018-1415-613844-13856Vol.25 is,14Thomson Reuters ISI