CEAZA
Potential Response to Selection of HSP70 as a Component of Innate Immunity in the Abalone Haliotis rufescens.
Brokordt, K., González, R., Farías, W., & Winkler, F.
Assessing components of the immune system may reflect disease resistance. In some invertebrates, heat shock proteins (HSPs) are immune effectors and have been described as potent activators of the innate immune response. Several diseases have become a threat to abalone farming worldwide; therefore, increasing disease resistance is considered to be a long-term goal for breeding programs. A trait will respond to selection only if it is determined partially by additive genetic variation. The aim of this study was to estimate the heritability (h2) and the additive genetic coefficient of variation (CVA) of HSP70 as a component of innate immunity of the abalone Haliotis rufescens, in order to assess its potential response to selection. These genetic components were estimated for the variations in the intracellular (in haemocytes) and extracellular (serum) protein levels of HSP70 in response to an immunostimulant agent in 60 full-sib families of H. rufescens. Levels of HSP70 were measured twice in the same individuals, first when they were young and again when they were pre-harvest adults, to estimate the repeatability (R), the h2 and the potential response to selection of these traits at these life stages. High HSP70 levels were observed in abalones subjected to immunostimulation in both the intracellular and extracellular haemolymph fractions. This is the first time that changes in serum levels of HSP70 have been reported in response to an immune challenge in molluscs. HSP70 levels in both fractions and at both ages showed low h2 and R, with values that were not significantly different from zero. However, HSP70 induced levels had a CVA of 13.3–16.2% in young adults and of 2.7–8.1% in pre-harvest adults. Thus, despite its low h2, HSP70 synthesis in response to an immune challenge in red abalone has the potential to evolve through selection because of its large phenotypic variation and the presence of additive genetic variance, especially in young animals.
Año: 2015
Palabras claves: Heat shock response, Immune response, Genetic polymorphism, Phenotypes, Young adults, Immune system proteins, Invertebrates, Crop genetics.
Referencia APA: Brokordt, K., González, R., Farías, W., & Winkler, F. (2015). Potential Response to Selection of HSP70 as a Component of Innate Immunity in the Abalone Haliotis rufescens. PLOS ONE, 10(11), e0141959.
Aeolian particles in marine cores as a tool for quantitative high-resolution reconstruction of upwelling favorable winds along coastal Atacama Desert, Northern Chile.
Flores-Aqueveque, V., Alfaro, S., Vargas, G., Rutllant, J., & Caquineau, S.
Upwelling areas play a major role in ocean biogeochemical cycles and ultimately in global climate, especially in higly productive regions as the South Eastern Pacific. This work is based on the analysis of the aeolian lithic particles accumulated in laminated sediments off Mejillones (23°S) in the eastern boundary Humboldt Current System. It proposes a high-resolution quantitative reconstruction of the upwelling-favorable southerly wind strength in the past ∼250 years, comparing its variability with changes in organic carbon export/preserved changes to the sea bottom. The increase of the intensity and variability in fluxes of particles larger than 35 μm and 100 μm since the second half of the 19th century and during the 20th century confirms a general strengthening of southerly winds in the region. Spectral analysis on the complete time-series of yearly depositional fluxes indicates that sedimentary variability can be explained by a combination of interannual (ENSO) to decadal (PDO) oscillations similar to the ones yielded by the analysis of the Interdecadal Pacific Oscillation index. However, when applied separately to the lithic fluxes of the first and last centuries of the time-series, the method shows that relative to the one of the interannual mode of variability, the influence of the decadal mode has increased in the recent period.
Based on the presence/absence of particles with sizes larger than 35/100 μm, each year of the time series is classified as a ‘Low wind’ (<6 m/s), ‘Intermediate wind’ (6–8 m/s), or ‘Strong wind’ (10 to >12 m/s) year. From the AD 1754–1820 period to the AD 1878–1998 one, the proportion of Low and Intermediate wind years decreased from 12% and 74% to 3% and 68%, respectively, whereas the proportion of strong wind years increased from 14% to 29%. For these periods the mean organic carbon also increased 22%, stating the strong relation between export/preservation productivity rate and southerly wind intensity.
In the recent period (from AD 1950 on) for which the Oceanic Niño Index is available, the strong wind years (AD 1982, 1983, 1994, and 1997) correspond to large values of this index, suggesting that constructive interferences that result from the interplay between interannual and decadal oscillations modes might explain in part the reinforcement of the winds along the North Chilean coast.
Año: 2015
Palabras claves:
Referencia APA: Flores-Aqueveque, V., Alfaro, S., Vargas, G., Rutllant, J., & Caquineau, S. (2015). Aeolian particles in marine cores as a tool for quantitative high-resolution reconstruction of upwelling favorable winds along coastal Atacama Desert, Northern Chile. Progress In Oceanography, 134, 244-255.
Pollen morphology of Cactaceae in Northern Chile.
Miesen, F., De Porras, M., & Maldonado, A.
Chile is habitat to over 140 species of cactus of which 45% are endemic and most of them grow in the arid northernmost part of the country between 18°-32°S. As the Cactaceae family plants are quite well adapted to arid environments, their fossil pollen may serve as a tool to reconstruct past environmental dynamics as well as to trace some issues regarding the family evolution or even some autoecological aspects. Aiming to create a reference atlas to be applied to some of these purposes, the pollen morphology of the following 14 different species of the Cactaceae family from Northern Chile was studied under optical microscopy: Cumulopuntia sphaerica, Maihueniopsis camachoi, Tunilla soehrensii, Echinopsis atacamensis, Echinopsis coquimbana, Haageocereus chilensis, Oreocereus hempelianus, Oreocereus leucotrichus, Copiapoa coquimbana, Eriosyce aurata, Eriosyce subgibbosa, Eulychnia breviflora, Browningia candelaris and Corryocactus brevistylus. Pollen grains of species of the subfamily Opuntioideae are spheroidal, apolar and periporate whereas grains of the subfamily Cactoideae are subspheroidal, bipolar and tricolpate and can be taxonomically differentiated between tribes. The results show that it is possible to identify pollen from the Cactaceae family at the genus level but pollen taxonomic resolution may be complicated to identify up to a specific level. A wider reference collection considering more characters than those included in the present study could improve this aspect in the near future.
Año: 2015
Palabras claves: Pollen morphology, Cactaceae, biogeography, palaeoecology, Chile.
Referencia APA: Miesen, F., De Porras, M., & Maldonado, A. (2015). Pollen morphology of Cactaceae in Northern Chile. Gayana Bot., 72(2), 258-271.
Definition of sanitary boundaries to prevent ISAv spread between salmon farms in southern Chile based on numerical simulations of currents.
Olivares, G., Sepúlveda, H., & Yannicelli, B.
The infectious Salmon Anemia virus (ISAv) is a pathogen that mainly affects the Atlantic Salmon (Salmo salar). It was detected in Norway in 1984 and in June 2007 appeared in Chile, producing a drop of more than 30% in the country's production level. It is expected that with certain regularity, outbreaks will continue to appear in Chile without the need of reintroducing the virus from foreign countries. We present a numerical study of the influence of winds and tides in the dispersion of lagrangian particles to simulate the transport of ISAv in the Aysen region, in southern Chile. This study combines the use of numerical models of the ocean and atmosphere, lagrangian tracking and biological aspects of ISAv infections. As in previous results, a wider dispersion of ISAv was observed during spring tides. Temporal changes in wind significantly modified the transport of viral particles from an infected center. Under similar forcing conditions, the areas of risk associated to culture sites separated by a few kilometers could be very different. Our main results remark the importance of the use of a detailed knowledge of hydrographic and atmospheric circulation in the definition of boundaries for sanitary management areas. We suggest that a methodology similar to the one presented in this study should be considered to define sanitary strategies to minimize the occurrence of native outbreaks of ISAv.
Año: 2015
Palabras claves: sanitary boundaries; ISAv; Atlantic Salmon; spread; numerical model; Chile.
Referencia APA: Olivares, G., Sepúlveda, H., & Yannicelli, B. (2015). Definition of sanitary boundaries to prevent ISAv spread between salmon farms in southern Chile based on numerical simulations of currents. Estuarine, Coastal And Shelf Science, 158, 31-39.
GRACE storage-runoff hystereses reveal the dynamics of regional watersheds.
Sproles, E., Leibowitz, S., Reager, J., Wigington, P., Famiglietti, J., & Patil, S.
We characterize how regional watersheds function as simple, dynamic systems through a series of hysteresis loops using measurements from NASA's Gravity Recovery and Climate Experiment (GRACE) satellites. These loops illustrate the temporal relationship between runoff and terrestrial water storage in three regional-scale watersheds (> 150 000 km2) of the Columbia River Basin, USA and Canada. The shape and size of the hysteresis loops are controlled by the climate, topography, and geology of the watershed. The direction of the hystereses for the GRACE signals moves in opposite directions from the isolated groundwater hystereses. The subsurface water (soil moisture and groundwater) hystereses more closely resemble the storage-runoff relationship of a soil matrix. While the physical processes underlying these hystereses are inherently complex, the vertical integration of terrestrial water in the GRACE signal encapsulates the processes that govern the non-linear function of regional-scale watersheds. We use this process-based understanding to test how GRACE data can be applied prognostically to predict seasonal runoff (mean Nash-Sutcliffe Efficiency of 0.91) and monthly runoff during the low flow/high demand month of August (mean Nash-Sutcliffe Efficiency of 0.77) in all three watersheds. The global nature of GRACE data allows this same methodology to be applied in other regional-scale studies, and could be particularly useful in regions with minimal data and in trans-boundary watersheds.
Año: 2015
Palabras claves:
Referencia APA: Leibowitz, S., Reager, J., Wigington, P., Famiglietti, J., & Patil, S. (2015). GRACE storage-runoff hystereses reveal the dynamics of regional watersheds. Hydrol. Earth Syst. Sci., 19(7), 3253-3272.
Calibrating the pollen signal in modern rodent middens from northern Chile to improve the interpretation of the late Quaternary midden record.
de Porras, M., Maldonado, A., Zamora-Allendes, A., & Latorre, C.
The use of rodent middens from northern Chile as paleoecological archives has at times been questioned due to concerns about their biogenic origin and the degree to which their record represents vegetation composition rather than rodent habits. To address such concerns, we carried out a modern calibration study to assess the representation of vegetation by pollen records from rodent middens. We compared vegetation censuses with soil-surface and midden (matrix and feces) pollen samples from sites between 21° and 28°S. The results show that (1) the pollen signal from the midden matrix provides a more realistic reflection of local vegetation than soil-surface samples due to the pollen-deposition processes that occur in middens; and (2) in contrast to feces pollen assemblages, which feature some biases, rodent dietary habits do not seem to influence midden matrix pollen assemblages, probably because midden agents are dietary generalists. Our finding that modern pollen data from rodent middens reflect vegetation patterns confirms the reliability of midden pollen records as paleoecological archives in northern Chile.
Año: 2015
Palabras claves: Rodent middens; Vegetation–pollen calibration; Northern Chile.
Referencia APA: de Porras, M., Maldonado, A., Zamora-Allendes, A., & Latorre, C. (2015). Calibrating the pollen signal in modern rodent middens from northern Chile to improve the interpretation of the late Quaternary midden record. Quaternary Research, 84(3), 301-311.
The response of nitrifying microbial assemblages to ammonium enrichment from salmon farm activities in a northern Chilean Fjord.
Elizondo-Patrone, C., Hernández, K., Yannicelli, B., Olsen, L., & Molina, V.
The consequences of aquaculture include alterations in nitrogen cycling in aquatic environments that may lead to ecosystem degradation. Herein salmon aquaculture release of ammonium (NH4+) to the water column and its effects on natural archaea and bacteria ammonia-oxidizers (AOA and AOB) and nitrite-oxidizing bacteria (NOB) community structure were studied in the Comau fjord using molecular approaches, such as: cloning (AOA and AOB richness), qPCR for C. Nitrosopumilus maritimus (AOA) and Nitrospina sp. (NOB) abundance (DNA) and RT-qPCR only for Nitrospina sp activity (RNA). Sampling was carried out in brackish (0.7–25 salinity, <5 m depth) and marine (>30 salinity, 25 m depth) waters during contrasting salmon production periods: rest (winter 2012), growth and harvest (summer and winter 2013). During the rest period, the highest NH4+ concentration was observed at Vodudahue River, whereas during productive periods NH4+ accumulated in the brackish layer inside salmon cages and in the vicinty (up to 700 m distance from the cages). The nitrifier community from the fjord reference station (Stn-C) was characterized by C. N. maritimus (AOA) and Nitrosomonas sp. (AOB) sequences affiliated with cosmopolitan ecotypes (e.g., marine, freshwater, hydrothermal), maxima abundances of C. N. maritimus (AOA) and Nitrospina sp. and extreme ranges of Nitrospina sp. activity occurred in the brackish layer. During productive periods, abundances of C. N. maritimus were co-varied with NH4+ concentrations inside salmon cages (summer) and the adjacent areas (winter). Productive periods were characterized by lower abundances but more homogeneity between brackish and marine areas than for the Stn-C nitrifiers. The physiological state of Nitrospina sp. estimated from cDNA:DNA ratios indicated higher growth during winter 2013 associated with NH4+ enrichment derived from production and river input. Our results suggest that in Comau Fjord, NH4+ enrichment events occur during salmon production and also naturally by river inputs, supporting an abundant and active nitrifying community potentially processing only part of the extra NH4+ that occurs, predominantly outside the salmon cages. Our work highlights the abundance and activities of nitrifying communities and identifies these communities as being sensitive to increased loads of NH4+.
Año: 2015
Palabras claves: Salmon farming; ammonium (NH4+) enrichment; nitrifying communities; Nitrospina sp.; Patagonian fjords.
Referencia APA: Elizondo-Patrone, C., Hernández, K., Yannicelli, B., Olsen, L., & Molina, V. (2015). The response of nitrifying microbial assemblages to ammonium enrichment from salmon farm activities in a northern Chilean Fjord. Estuarine, Coastal And Shelf Science, 166, 131-142. http://dx.doi.org/10.1016/j.ecss.2015.03.021
Herbivore-Alga Interaction Strength Influences Spatial Heterogeneity in a Kelp-Dominated Intertidal Community.
Aguilera, M., Valdivia, N., & Broitman, B.
There is a general consensus that marine herbivores can affect algal species composition and abundance, but little empirical work exists on the role of herbivores as modifiers of the spatial structure of resource assemblages. Here, we test the consumption/bulldozing effects of the molluscan grazer Enoplochiton niger and its influence on the spatial structure of a low intertidal community dominated by the bull kelp Durvillaea antarctica and the kelp Lessonia spicata. Through field experiments conducted at a rocky intertidal shore in north-central Chile (~30°-32°S), the edge of the grazer and algae geographic distributions, we estimated the strength and variability of consumptive effects of the grazer on different functional group of algae. We also used data from abundance field surveys to evaluate spatial co-occurrence patterns of the study species. Exclusion-enclosure experiments showed that E. niger maintained primary space available by preventing algal colonization, even of large brown algae species. The grazing activity of E. niger also reduced spatial heterogeneity of the ephemeral algal species, increasing bare space availability and variability through time in similar ways to those observed for the collective effect with other grazers. Overall, our result suggests that E. niger can be considered an important modifier of the spatial structure of the large brown algae-dominated community. Effects of E. niger on resource variability seem to be directly related to its foraging patterns, large body size, and population densities, which are all relevant factors for management and conservation of the large brown algae community. Our study thus highlights the importance of considering functional roles and identity of generalist consumers on spatial structure of the entire landscape.
Año: 2015
Palabras claves: Algae, Niger, Seaweed, Herbivory, Grazing, Population density, Foraging, Fronds.
Referencia APA: Aguilera, M., Valdivia, N., & Broitman, B. (2015). Herbivore-Alga Interaction Strength Influences Spatial Heterogeneity in a Kelp-Dominated Intertidal Community. PLOS ONE, 10(9), e0137287.
Geomorphology, internal structure, and successive development of a glacier foreland in the semiarid Chilean Andes (Cerro Tapado, upper Elqui Valley, 30°08′ S., 69°55′ W.).
Monnier, S., Kinnard, C., Surazakov, A., & Bossy, W.
We use geomorphological analysis, sedimentological survey, remote sensing, and ground penetrating radar (GPR) in order to understand the complex landform assemblage found in front of the Cerro Tapado glacier in the upper Elqui River catchment, semiarid Andes of Chile. The geomorphological analysis highlights prominent boundaries dividing the landform assemblage into (from the upper part to the lower part) an upper latero-frontal moraine complex, an upper debris-covered glacier, a lower debris-covered glacier, two rock glaciers, and a lower morainic complex. The sedimentological survey highlights the rather small size of the surface debris (in general < 20 cm) and the predominance of porphyritic rhyolite. Remote sensing data show that, between 1956 and 2010, considerable (> 400 m) receding of the glacier occurred, along with downslope displacements (dm–m·y− 1) of most of the landform units and a significant evolution of the thermokarst features on the debris-covered glaciers. Considerable surface lowering occurred in the upper part of the assemblage, while localized bulging is seen along the morphological boundaries in the lower units. The GPR profiles highlight spectacular internal structure in the upper debris-covered glacier with up to 80 m of buried ice. In the other landform units, the internal structure is less visible and more heterogeneous. The analysis of the radar wave velocity along the GPR profiles reveals the occurrence of air-filled and moist zones in the internal structure. The geomorphological assemblage is fundamentally characterized by its morphological, structural, and dynamical boundaries and defined as a young (probably < 2000 years) polygenetic construction with landform units having added to/overlapped one another. The rock glaciers do not derive from the present debris-covered glacier but preexist to it.
Año: 2014
Palabras claves: Landform assemblage; Debris-covered glacier; Rock glacier; Moraines; Ground-penetrating radar; Subsurface ice.
Referencia APA: Monnier, S., Kinnard, C., Surazakov, A., & Bossy, W. (2014). Geomorphology, internal structure, and successive development of a glacier foreland in the semiarid Chilean Andes (Cerro Tapado, upper Elqui Valley, 30°08′ S., 69°55′ W.). Geomorphology, 207, 126-140.
Formulation, calibration and validation of the DAIS model (version 1), a simple Antarctic Ice Sheet model sensitive to variations of sea level and ocean subsurface temperature.
Shaffer, G.
The DCESS (Danish Center for Earth System Science) Antarctic Ice Sheet (DAIS) model is presented. Model hindcasts of Antarctic ice sheet (AIS) sea level equivalent are forced by reconstructed Antarctic temperatures, global mean sea level and high-latitude, ocean subsurface temperatures, the latter calculated using the DCESS model forced by reconstructed global mean atmospheric temperatures. The model is calibrated by comparing such hindcasts for different model configurations with paleoreconstructions of AIS sea level equivalent from the last interglacial, the last glacial maximum and the mid-Holocene. The calibrated model is then validated against present estimates of the rate of AIS ice loss. It is found that a high-order dependency of ice flow at the grounding line on water depth there is needed to capture the observed response of the AIS at ice age terminations. Furthermore, it is found that a dependency of this ice flow on ocean subsurface temperature by way of ice shelf demise and a resulting buttressing decrease is needed to explain the contribution of the AIS to global mean sea level rise at the last interglacial. When forced and calibrated in this way, model hindcasts of the rate of present-day AIS ice loss agree with recent, data-based estimates of this ice loss rate.
Año: 2014
Palabras claves:
Referencia APA: Shaffer, G. (2014).Formulation, calibration and validation of the DAIS model (version 1), a simple Antarctic ice sheet model sensitive to variations of sea level and ocean subsurface temperature. Geoscientific Model Development, 7(4), 1803-1818.
Genetic diversity of Colobanthus quitensis across the Drake Passage.
Acuña-Rodríguez, I., Oses, R., Cortés-Vasquez, J., Torres-Díaz, C., & Molina-Montenegro, M.
The Drake Passage arises as a likely route for gene flow into Antarctica, as it is the shortest path between this continent and the rest of the world. Despite this, long-distance dispersion into Antarctica could be particularly complex for terrestrial biota. To compare the levels of genetic diversity between Antarctic and South American populations of the Antarctic pearlwort, Colobanthus quitensis, we conducted the first estimation of genetic diversity in this species using amplified fragment length polymorphism. Four populations across the Drake Passage were selected and their genetic composition was characterized. Differences among the levels of genetic diversity were found between the populations analysed as well as between their allelic identities. However, interestingly, their spatial distribution across the Drake Passage suggests a north-to-south gradient of increasing genetic diversity.
Año: 2014
Palabras claves: AFLP, Antarctic vascular plants, Colobanthus quitensis, genetic diversity.
Referencia APA: Acuña-Rodríguez, I., Oses, R., Cortés-Vasquez, J., Torres-Díaz, C., & Molina-Montenegro, M. (2014). Genetic diversity of Colobanthus quitensis across the Drake Passage. Plant Genetic Resources, 12(01), 147-150.
Effect of grazing on distribution and recovery of harvested stands of Lessonia berteroana kelp in northern Chile.
Oróstica, M., Aguilera, M., Donoso, G., Vásquez, J., & Broitman, B.
Understanding the ecological factors regulating exploited natural communities is important in establishing conservation and management strategies. Since the 1960s, artisanal fishermen have harvested up to 300000 dry tons yr-1 of wild populations of Lessonia spp. kelps. Adult kelps form a key habitat on the rocky shores of Chile, and benthic grazers regulate kelp populations by grazing or bulldozing microscopic and juvenile stages. To establish the role of the grazer assemblage in the recovery of kelp stands following harvesting, we conducted a manipulative experiment simulating artisanal kelp extraction and then manipulating the presence of grazers. We followed community succession and spatial distribution of L. berteroana recruits in manipulated and control rocky shore platforms for ca. 12 mo. Inter-individual distances of recruits and spatial autocorrelation analyses showed that the presence of grazers determined a patchy distributional pattern of L. berteroana. The aggregated spatial pattern of kelp recruits in the presence of grazers was followed by numerous coalescence events between small holdfasts, but no coalescence events were observed between recruits in the grazer removal areas. Our results suggest that grazing and recruit coalescence play an important role in the recovery of kelp stands following artisanal harvesting. Incorporating these processes into conservation and management strategies may bolster current strategies, which are based solely on the spatial structure of kelp stands.
Año: 2014
Palabras claves: Algae-herbivore, Harvesting, Grazers, Kelp communities, Spatial structure.
Referencia APA: Oróstica, M., Aguilera, M., Donoso, G., Vásquez, J., & Broitman, B. (2014). Effect of grazing on distribution and recovery of harvested stands of Lessonia berteroana kelp in northern Chile. Marine Ecology Progress Series, 511, 71-82.