CEAZA
Modelling the hydrological response of debris‐free and debris‐covered glaciers to present climatic conditions in the semiarid Andes of central Chile.
Ayala, A., Pellicciotti, F., MacDonell, S., McPhee, J., Vivero, S., Campos, C., & Egli, P.
We apply the process-based, distributed TOPKAPI-ETH glacio-hydrological model to a glacierized catchment (19% glacierized) in the semiarid Andes of central Chile. The semiarid Andes provides vital freshwater resources to valleys in Chile and Argentina, but only few glacio-hydrological modelling studies have been conducted, and its dominant hydrological processes remain poorly understood. The catchment contains two debris-free glaciers reaching down to 3900 m asl (Bello and Yeso glaciers) and one debris-covered avalanche-fed glacier reaching to 3200 m asl (Piramide Glacier). Our main objective is to compare the mass balance and runoff contributions of both glacier types under current climatic conditions. We use a unique dataset of field measurements collected over two ablation seasons combined with the distributed TOPKAPI-ETH model that includes physically oriented parameterizations of snow and ice ablation, gravitational distribution of snow, snow albedo evolution and the ablation of debris-covered ice. Model outputs indicate that while the mass balance of Bello and Yeso glaciers is mostly explained by temperature gradients, the Piramide Glacier mass balance is governed by debris thickness and avalanches and has a clear non-linear profile with elevation as a result. Despite the thermal insulation effect of the debris cover, the mass balance and contribution to runoff from debris-free and debris-covered glaciers are similar in magnitude, mainly because of elevation differences. However, runoff contributions are distinct in time and seasonality with ice melt starting approximately four weeks earlier from the debris-covered glacier, what is of relevance for water resources management. At the catchment scale, snowmelt is the dominant contributor to runoff during both years. However, during the driest year of our simulations, ice melt contributes 42 ± 8% and 67 ± 6% of the annual and summer runoff, respectively. Sensitivity analyses show that runoff is most sensitive to temperature and precipitation gradients, melt factors and debris cover thickness. Copyright © 2016 John Wiley & Sons, Ltd.
Año: 2016
Palabras claves:
Referencia APA: Ayala, A., Pellicciotti, F., MacDonell, S., McPhee, J., Vivero, S., Campos, C., & Egli, P. (2016). Modelling the hydrological response of debris‐free and debris‐covered glaciers to present climatic conditions in the semiarid Andes of central Chile. Hydrological Processes, 30(22), 4036-4058.
Seasonal variability of the Ekman transport and pumping in the upwelling system off central-northern Chile (∼ 30° S) based on a high-resolution atmospheric regional model (WRF).
Bravo, L., Ramos, M., Astudillo, O., Dewitte, B., & Goubanova, K.
Two physical mechanisms can contribute to coastal upwelling in eastern boundary current systems: offshore Ekman transport due to the predominant alongshore wind stress and Ekman pumping due to the cyclonic wind stress curl, mainly caused by the abrupt decrease in wind stress (drop-off) in a cross-shore band of 100 km. This wind drop-off is thought to be an ubiquitous feature in coastal upwelling systems and to regulate the relative contribution of both mechanisms. It has been poorly studied along the central-northern Chile region because of the lack in wind measurements along the shoreline and of the relatively low resolution of the available atmospheric reanalysis. Here, the seasonal variability in Ekman transport, Ekman pumping and their relative contribution to total upwelling along the central-northern Chile region (∼ 30° S) is evaluated from a high-resolution atmospheric model simulation. As a first step, the simulation is validated from satellite observations, which indicates a realistic representation of the spatial and temporal variability of the wind along the coast by the model. The model outputs are then used to document the fine-scale structures in the wind stress and wind curl in relation to the topographic features along the coast (headlands and embayments). Both wind stress and wind curl had a clear seasonal variability with annual and semiannual components. Alongshore wind stress maximum peak occurred in spring, second increase was in fall and minimum in winter. When a threshold of −3 × 10−5 s−1 for the across-shore gradient of alongshore wind was considered to define the region from which the winds decrease toward the coast, the wind drop-off length scale varied between 8 and 45 km. The relative contribution of the coastal divergence and Ekman pumping to the vertical transport along the coast, considering the estimated wind drop-off length, indicated meridional alternation between both mechanisms, modulated by orography and the intricate coastline. Roughly, coastal divergence predominated in areas with low orography and headlands. Ekman pumping was higher in regions with high orography and the presence of embayments along the coast. In the study region, the vertical transport induced by coastal divergence and Ekman pumping represented 60 and 40 % of the total upwelling transport, respectively. The potential role of Ekman pumping on the spatial structure of sea surface temperature is also discussed.
Año: 2016
Palabras claves: Cryoconite hole connectivity on the Wright Lower Glacier, McMurdo Dry Valleys, Antarctica.
Referencia APA: Bravo, L., Ramos, M., Astudillo, O., Dewitte, B., & Goubanova, K. (2016). Seasonal variability of the Ekman transport and pumping in the upwelling system off central-northern Chile (∼ 30° S) based on a high-resolution atmospheric regional model (WRF). Ocean Science, 12(5), 1049-1065.
Seasonal variability of the oxygen minimum zone off Peru in a high-resolution regional coupled model.
Vergara, O., Dewitte, B., Montes, I., Garçon, V., Ramos, M., Paulmier, A., & Pizarro, O.
In addition to being one of the most productive upwelling systems, the oceanic region off Peru is embedded in one of the most extensive oxygen minimum zones (OMZs) of the world ocean. The dynamics of the OMZ off Peru remain uncertain, partly due to the scarcity of data and to the ubiquitous role of mesoscale activity on the circulation and biogeochemistry. Here we use a high-resolution coupled physical/biogeochemical model simulation to investigate the seasonal variability of the OMZ off Peru. The focus is on characterizing the seasonal cycle in dissolved O2 (DO) eddy flux at the OMZ boundaries, including the coastal domain, viewed here as the eastern boundary of the OMZ, considering that the mean DO eddy flux in these zones has a significant contribution to the total DO flux. The results indicate that the seasonal variations of the OMZ can be interpreted as resulting from the seasonal modulation of the mesoscale activity. Along the coast, despite the increased seasonal low DO water upwelling, the DO peaks homogeneously over the water column and within the Peru Undercurrent (PUC) in austral winter, which results from mixing associated with the increase in both the intraseasonal wind variability and baroclinic instability of the PUC. The coastal ocean acts therefore as a source of DO in austral winter for the OMZ core, through eddy-induced offshore transport that is also shown to peak in austral winter. In the open ocean, the OMZ can be divided vertically into two zones: an upper zone above 400 m, where the mean DO eddy flux is larger on average than the mean seasonal DO flux and varies seasonally, and a lower part, where the mean seasonal DO flux exhibits vertical–zonal propagating features that share similar characteristics than those of the energy flux associated with the annual extratropical Rossby waves. At the OMZ meridional boundaries where the mean DO eddy flux is large, the DO eddy flux has also a marked seasonal cycle that peaks in austral winter (spring) at the northern (southern) boundary. In the model, the amplitude of the seasonal cycle is 70 % larger at the southern boundary than at the northern boundary. Our results suggest the existence of distinct seasonal regimes for the ventilation of the OMZ by eddies at its boundaries. Implications for understanding the OMZ variability at longer timescales are discussed.
Año: 2016
Palabras claves:
Referencia APA: ergara, O., Dewitte, B., Montes, I., Garçon, V., Ramos, M., Paulmier, A., & Pizarro, O. (2016). Seasonal variability of the oxygen minimum zone off Peru in a high-resolution regional coupled model. Biogeosciences, 13(15), 4389-4410.
Biogeochemical characteristics of a long-lived anticyclonic eddy in the eastern South Pacific Ocean.
Cornejo D'Ottone, M., Bravo, L., Ramos, M., Pizarro, O., Karstensen, J., Gallegos, M., Correa-Ramirez, M., Silva, N., Farias, L. & Karp-Boss, L.
Mesoscale eddies are important, frequent, and persistent features of the circulation in the eastern South Pacific (ESP) Ocean, transporting physical, chemical and biological properties from the productive shelves to the open ocean. Some of these eddies exhibit subsurface hypoxic or suboxic conditions and may serve as important hotspots for nitrogen loss, but little is known about oxygen consumption rates and nitrogen transformation processes associated with these eddies. In the austral fall of 2011, during the Tara Oceans expedition, an intrathermocline, anticyclonic, mesoscale eddy with a suboxic (< 2 µmol kg−1 of O2), subsurface layer (200–400 m) was detected ∼ 900 km off the Chilean shore (30° S, 81° W). The core of the eddy's suboxic layer had a temperature-salinity signature characteristic of Equatorial Subsurface Water (ESSW) that at this latitude is normally restricted to an area near the coast. Measurements of nitrogen species within the eddy revealed undersaturation (below 44 %) of nitrous oxide (N2O) and nitrite accumulation (> 0.5 µM), suggesting that active denitrification occurred in this water mass. Using satellite altimetry, we were able to track the eddy back to its region of formation on the coast of central Chile (36.1° S, 74.6° W). Field studies conducted in Chilean shelf waters close to the time of eddy formation provided estimates of initial O2 and N2O concentrations of the ESSW source water in the eddy. By the time of its offshore sighting, concentrations of both O2 and N2O in the subsurface oxygen minimum zone (OMZ) of the eddy were lower than concentrations in surrounding water and “source water” on the shelf, indicating that these chemical species were consumed as the eddy moved offshore. Estimates of apparent oxygen utilization rates at the OMZ of the eddy ranged from 0.29 to 44 nmol L−1 d−1 and the rate of N2O consumption was 3.92 nmol L−1 d−1. These results show that mesoscale eddies affect open-ocean biogeochemistry in the ESP not only by transporting physical and chemical properties from the coast to the ocean interior but also during advection, local biological consumption of oxygen within an eddy further generates conditions favorable to denitrification and loss of fixed nitrogen from the system.
Año: 2016
Palabras claves:
Referencia APA: Cornejo D'Ottone, M., Bravo, L., Ramos, M., Pizarro, O., Karstensen, J., Gallegos, M., Correa-Ramirez, M., Silva, N., Farias, L. & Karp-Boss, L. (2016). Biogeochemical characteristics of a long-lived anticyclonic eddy in the eastern South Pacific Ocean. Biogeosciences (BG), 13(10), 2971-2979.
Microbial Activity Response to Solar Radiation across Contrasting Environmental Conditions in Salar de Huasco, Northern Chilean Altiplano.
Hernández, K. L., Yannicelli, B., Olsen, L. M., Dorador, C., Menschel, E. J., Molina, V., Remonsellez, F., Hengst, M. B. & Jeffrey, W. H.
In high altitude environments, extreme levels of solar radiation and important differences of ionic concentrations over narrow spatial scales may modulate microbial activity. In Salar de Huasco, a high-altitude wetland in the Andean mountains, the high diversity of microbial communities has been characterized and associated with strong environmental variability. Communities that differed in light history and environmental conditions, such as nutrient concentrations and salinity from different spatial locations, were assessed for bacterial secondary production (BSP, 3H-leucine incorporation) response from short-term exposures to solar radiation. We sampled during austral spring seven stations categorized as: (a) source stations, with recently emerged groundwater (no-previous solar exposure); (b) stream running water stations; (c) stations connected to source waters but far downstream from source points; and (d) isolated ponds disconnected from ground sources or streams with a longer isolation and solar exposure history. Very high values of 0.25 μE m-2 s-1, 72 W m-2 and 12 W m-2 were measured for PAR, UVA, and UVB incident solar radiation, respectively. The environmental factors measured formed two groups of stations reflected by principal component analyses (near to groundwater sources and isolated systems) where isolated ponds had the highest BSP and microbial abundance (35 microalgae taxa, picoeukaryotes, nanoflagellates, and bacteria) plus higher salinities and PO43- concentrations. BSP short-term response (4 h) to solar radiation was measured by 3H-leucine incorporation under four different solar conditions: full sun, no UVB, PAR, and dark. Microbial communities established in waters with the longest surface exposure (e.g., isolated ponds) had the lowest BSP response to solar radiation treatments, and thus were likely best adapted to solar radiation exposure contrary to ground source waters. These results support our light history (solar exposure) hypothesis where the more isolated the community is from ground water sources, the better adapted it is to solar radiation. We suggest that factors other than solar radiation (e.g., salinity, PO43-, NO3-) are also important in determining microbial productivity in heterogeneous environments such as the Salar de Huasco.
Año: 2016
Palabras claves:
Referencia APA: Hernández, K. L., Yannicelli, B., Olsen, L. M., Dorador, C., Menschel, E. J., Molina, V., Remonsellez, F., Hengst, M. B. & Jeffrey, W. H. (2016). Microbial Activity Response to Solar Radiation across Contrasting Environmental Conditions in Salar de Huasco, Northern Chilean Altiplano. Frontiers in Microbiology, 7.
A diet rich in polyunsaturated fatty acids improves the capacity for HSP70 synthesis in adult scallop Argopecten purpuratus and their offspring.
Pérez, H. M., Brokordt, K., Gallardo, A., Vidal, I., & Guderley, H
In scallops, aerobic power requirements of gonad maturation reduce HSP70 synthesis capacity in response to thermal or hypoxia stress. As dietary lipid quality is crucial for membrane function, we predicted that supplementing Argopecten purpuratus broodstock with essential polyunsaturated fatty acids (PUFA) during gonadal maturation would mitigate the loss in adult performance while favoring that of larvae. Scallops were fed during reproductive conditioning with microalgal diets with high and low PUFA contents, while a control group was maintained in natural conditions. After maturation, scallops of each treatment were kept at normal temperature (18 °C) or stressed by increasing the temperature (+6 °C). Mature scallops fed each diet were stimulated to spawn, and the ensuing larvae were exposed to handling and thermal stress. Relative transcription of hsp70 mRNA was assessed by RT-qPCR, and HSP70 proteins were quantified by ELISA. Feeding a high-PUFA diet during reproductive conditioning enhanced HSP70 induction (at transcription and protein levels) by mature A. purpuratus in response to thermal stress. By contrast, neither scallops matured in the natural environment nor those fed the low-PUFA diet increased HSP70 levels after thermal stress; hsp70 mRNA levels were also reduced. Offspring from broodstock fed a high-PUFA diet increased induction of HSP70 after exposure to handling and handling plus thermal stress relative to offspring of scallops fed a low-PUFA diet. Survival of these larvae was also enhanced. Feeding adult scallops with appropriate PUFA during reproductive conditioning could improve adult stress responses and favor stress responses and survival of ensuing larvae.
Año: 2016
Palabras claves:
Referencia APA: Pérez, H. M., Brokordt, K., Gallardo, A., Vidal, I., & Guderley, H. (2016). A diet rich in polyunsaturated fatty acids improves the capacity for HSP70 synthesis in adult scallop Argopecten purpuratus and their offspring. Marine Biology, 163(9), 193.
Chemical and isotopic assessment of surface water–shallow groundwater interaction in the arid Grande river basin, North-Central Chile.
Oyarzún, R., Zambra, S., Maturana, H., Oyarzún, J., Aguirre, E., & Kretschmer, N.
This paper analyses the composition of surface water and shallow groundwater in the Grande River basin, North-Central Chile, using this information to characterize water interactions. Chemical and isotopic data for surface water and groundwater (7 and 6 sampling locations, respectively) were obtained from three sampling campaigns performed in March–April (autumn), August–September (late winter) and December (early summer) 2012. Precipitation samples were also collected. Data was processed using spatial distribution charts, Piper and Stiff diagrams, and multivariate analysis. In general, the results for each method converge on a high degree of connectivity between surface water and shallow groundwater in the study area. Furthermore, approximately a 10% of groundwater contribution to the surface flow discharge was estimated for a particular reach. This multi-method approach was useful for the characterization of surface water–groundwater interactions in the Grande River basin, and may become a suitable and replicable scheme for studies in arid and semi-arid basins facing similar water management challenges.
Año: 2016
Palabras claves: integrated water management, isotope tracers, over-allocated basin.
Referencia APA: Oyarzún, R., Zambra, S., Maturana, H., Oyarzún, J., Aguirre, E., & Kretschmer, N. (2016). Chemical and isotopic assessment of surface water–shallow groundwater interaction in the arid Grande river basin, North-Central Chile. Hydrological Sciences Journal, 61(12), 2193-2204.
Spore dispersal in the intertidal kelp Lessonia spicata: macrochallenges for the harvested Lessonia species complex at microscales of space and time.
Parada, G. M., Tellier, F., & Martínez, E. A.
The intertidal coast of Chile has two cryptic kelp species, Lessonia spicata and L. berteroana, which share closely situated, but not overlapping, high-energy habitats. Their populations recover slowly after major disturbances and massive mortalities, suggesting that dispersal from remnant populations is strongly limited. This low dispersal is also a factor that probably favours the speciation process. Understanding the limiting factors for spore dispersal is crucial. Here we evaluated 1. spore dispersal and spore dilution over distance, 2. if submersion in calm waters for a specific period of time is needed for the settlement of spores before exposure to water movement, and 3. duration of spore attachment ability. Results were consistent with the hypothesis of low-distance dispersal of spores: stained-spore dilution was high at short spatial scales (<4 m); spores settled quickly (1–2 min) even under constant water movement, but they lost the ability to attach rapidly (≤16 h). Water motion did not affect spore attachment to the substratum, a fact probably resulting from an adaptation to high energy intertidal habitats. The very low dispersal range of the spores may explain the strong genetic differentiation at small spatial scales, the speciation event that occurred within the Lessonia species complex and the slow recovery of L. berteroana after massive mortalities occurring with the 1982/1983 El Niño Southern oscillation event.
Año: 2016
Palabras claves: Laminariales; seaweeds; settlement; spore attachment.
Referencia APA: Parada, G. M., Tellier, F., & Martínez, E. A. (2016). Spore dispersal in the intertidal kelp Lessonia spicata: macrochallenges for the harvested Lessonia species complex at microscales of space and time. Botanica Marina, 59(4), 283-289.
Artificial breakwaters as garbage bins: Structural complexity enhances anthropogenic litter accumulation in marine intertidal habitats.
Aguilera, M., Broitman, B., & Thiel, M.
Coastal urban infrastructures are proliferating across the world, but knowledge about their emergent impacts is still limited. Here, we provide evidence that urban artificial reefs have a high potential to accumulate the diverse forms of litter originating from anthropogenic activities around cities. We test the hypothesis that the structural complexity of urban breakwaters, when compared with adjacent natural rocky intertidal habitats, is a driver of anthropogenic litter accumulation. We determined litter abundances at seven sites (cities) and estimated the structural complexity in both urban breakwaters and adjacent natural habitats from northern to central Chile, spanning a latitudinal gradient of ∼15° (18°S to 33°S). Anthropogenic litter density was significantly higher in coastal breakwaters when compared to natural habitats (∼15.1 items m−2 on artificial reefs versus 7.4 items m−2 in natural habitats) at all study sites, a pattern that was temporally persistent. Different litter categories were more abundant on the artificial reefs than in natural habitats, with local human population density and breakwater extension contributing to increase the probabilities of litter occurrence by ∼10%. In addition, structural complexity was about two-fold higher on artificial reefs, with anthropogenic litter density being highest at intermediate levels of structural complexity. Therefore, the spatial structure characteristic of artificial reefs seems to enhance anthropogenic litter accumulation, also leading to higher residence time and degradation potential. Our study highlights the interaction between coastal urban habitat modification by establishment of artificial reefs, and pollution. This emergent phenomenon is an important issue to be considered in future management plans and the engineering of coastal ecosystems.
Año: 2016
Palabras claves: Artificial reefs; Anthropogenic litter; Rocky intertidal; Structural complexity; Shoreline.
Referencia APA: Aguilera, M., Broitman, B., & Thiel, M. (2016). Artificial breakwaters as garbage bins: Structural complexity enhances anthropogenic litter accumulation in marine intertidal habitats. Environmental Pollution, 214, 737-747.
Hydrologic Landscape Characterization for the Pacific Northwest, USA.
Leibowitz, S., Comeleo, R., Wigington, P., Weber, M., Sproles, E., & Sawicz, K.
We update the Wigington et al. (2013) hydrologic landscape (HL) approach to make it more broadly applicable and apply the revised approach to the Pacific Northwest (PNW; i.e., Oregon, Washington, and Idaho). Specific changes incorporated are the use of assessment units based on National Hydrography Dataset Plus V2 catchments, a modified snowmelt model validated over a broader area, an aquifer permeability index that does not require preexisting aquifer permeability maps, and aquifer and soil permeability classes based on uniform criteria. Comparison of Oregon results for the revised and original approaches found fewer and larger assessment units, loss of summer seasonality, and changes in rankings and proportions of aquifer and soil permeability classes. Differences could be explained by three factors: an increased assessment unit size, a reduced number of permeability classes, and use of smaller cutoff values for the permeability classes. The distributions of the revised HLs in five groups of Oregon rivers were similar to the original HLs but less variable. The improvements reported here should allow the revised HL approach to be applied more often in situations requiring hydrologic classification and allow greater confidence in results. We also apply the map results to the development of hydrologic landscape regions.
Año: 2016
Palabras claves: Hydrologic classification; hydrologic cycle; watersheds; rivers/streams; runoff; geospatial analysis; National Hydrography Dataset, NHD; Pacific Northwest.
Referencia APA: Leibowitz, S., Comeleo, R., Wigington, P., Weber, M., Sproles, E., & Sawicz, K. (2016). Hydrologic Landscape Characterization for the Pacific Northwest, USA. JAWRA Journal Of The American Water Resources Association, 52(2), 473-493. 1688.12402
Climatic characteristics of the semi-arid Coquimbo Region in Chile.
Montecinos, S., Gutiérrez, J., López-Cortés, F., & López, D.
The climate of the Coquimbo Region, north-central Chile is driven by atmospheric, oceanic and orographic factors. The southeast Pacific anticyclone, the cold Humboldt Current and the rugged topography that characterize the zone, determine thermally induced wind regimes and the formation of low stratocumulus along the coastline. Low precipitation and high solar radiation cause important climatic altitudinal gradients, especially on temperature and humidity, thus different climatic areas can be identified in the region. We summarized the general climatic characteristics of the study area and analyzed meteorological data to understand the behavior of the environmental variables. We used mesoscale modeling to evaluate the spatial characteristics of the mean air temperature, humidity and wind. These atmospheric variables present a strong elevation gradient. The particular topographic characteristics of the region favor the development of a thermally induced wind regime, where land and sea breezes and valley winds are observed.
Año: 2016
Palabras claves: Atmospheric modeling; Semi-arid zones; Desert.
Referencia APA: Montecinos, S., Gutiérrez, J., López-Cortés, F., & López, D. (2016). Climatic characteristics of the semi-arid Coquimbo Region in Chile. Journal Of Arid Environments, 126, 7-11.
Water deficit stress-induced changes in carbon and nitrogen partitioning in Chenopodium quinoa Willd.
Bascuñán-Godoy, L., Reguera, M., Abdel-Tawab, Y., & Blumwald, E.
Water deficit stress followed by re-watering during grain filling resulted in the induction of the ornithine pathway and in changes in Quinoa grain quality.
The genetic diversity of Chenopodium quinoa Willd. (Quinoa) is accompanied by an outstanding environmental adaptability and high nutritional properties of the grains. However, little is known about the biochemical and physiological mechanisms associated with the abiotic stress tolerance of Quinoa. Here, we characterized carbon and nitrogen metabolic changes in Quinoa leaves and grains in response to water deficit stress analyzing their impact on the grain quality of two lowland ecotypes (Faro and BO78). Differences in the stress recovery response were found between genotypes including changes in the activity of nitrogen assimilation-associated enzymes that resulted in differences in grain quality. Both genotypes showed a common strategy to overcome water stress including the stress-induced synthesis of reactive oxygen species scavengers and osmolytes. Particularly, water deficit stress induced the stimulation of the ornithine and raffinose pathways. Our results would suggest that the regulation of C- and N partitioning in Quinoa during grain filling could be used for the improvement of the grain quality without altering grain yields.
Año: 2016
Palabras claves: C and N partitioning, Grain nutritional quality, Ornithine pathway, Quinoa, ROS scavengers, Stress recovery, Source and sink interactions, Water deficit stress.
Referencia APA: Bascuñán-Godoy, L., Reguera, M., Abdel-Tawab, Y., & Blumwald, E. (2016). Water deficit stress-induced changes in carbon and nitrogen partitioning in Chenopodium quinoa Willd. Planta, 243(3), 591-603.