CEAZA
Upwelling response to atmospheric coastal jets off central Chile: A modeling study of the October 2000 event.
Renault, L., Dewitte, B., Marchesiello, P., Illig, S., Echevin, V., & Cambon, G., Ramos, M., Astudillo, O., Minnis, P., Ayers, J.K.
The spatial and temporal variability of nearshore winds in eastern boundary current systems affect the oceanic heat balance that drives sea surface temperature changes. In this study, regional atmospheric and oceanic simulations are used to document such processes during an atmospheric coastal jet event off central Chile. The event is well reproduced by the atmospheric model and is associated with the migration of an anomalous anticyclone in the southeastern Pacific region during October 2000. A robust feature of the simulation is a sharp coastal wind dropoff, which is insensitive to model resolution. As expected, the simulated oceanic response is a significant sea surface cooling. A surface heat budget analysis shows that vertical mixing is a major contributor to the cooling tendency both in the jet core area and in the nearshore zone where the magnitude of this term is comparable to the magnitude of vertical advection. Sensitivity experiments show that the oceanic response in the coastal area is sensitive to wind dropoff representation. This is because total upwelling, i.e., the sum of coastal upwelling and Ekman pumping, depends on the scale of wind dropoff. Because the latter is much larger than the upwelling scale, coastal wind dropoff has only a weak positive effect on vertical velocities driven by Ekman pumping but has a strong negative effect on coastal upwelling. Interestingly though, the weakening of coastal winds in the dropoff zone has a larger effect on vertical mixing than on vertical advection, with both effects contributing to a reduction of cooling.
Año: 2012
Palabras claves: atmospheric coastal jets; eastern boundary current systems; numerical simulation; ocean/atmosphere interactions; upwelling; wind dropoff
Referencia APA: Renault, L., Dewitte, B., Marchesiello, P., Illig, S., Echevin, V., & Cambon, G., Ramos, M., Astudillo, O., Minnis, P., Ayers, J.K. (2012). Upwelling response to atmospheric coastal jets off central Chile: A modeling study of the October 2000 event. J. Geophys. Res., 117(C2), n/a-n/a.
Interspecific Competition for Shelters in Territorial and Gregarious Intertidal Grazers: Consequences for Individual Behaviour.
Aguilera, M. & Navarrete, S.
Experiments have shown that interspecific interactions within consumer guilds can alter patterns of distribution, abundance and size of species. Plastic behavioural responses can be modulated by agonistic interactions. In many cases, consumers compete for space and shelters, and these interactions change the manner in which they exploit food. This study investigates the consequences of competition in the spatial and temporal organization of behaviour of intertidal grazers, which share algal resources and the use of rock crevices while resting, but exhibit different body sizes, spatial behaviour and foraging modes. We evaluate interaction strength between small gregarious Siphonaria lessoni and the larger territorial keyhole limpet Fissurella crassa and between S. lessoni and the medium-size gregarious chiton Chiton granosus. Using field manipulations and artificial arenas in the laboratory, we tested whether the use of crevices, micro-spatial distribution and activity are modified by the density of conspecifics and the presence of heterospecifics. Our results show that small-scale spatial segregation observed in the field between S. lessoni and C. granosus result from species-specific differences in habitat use. In turn, we found evidence that spatial segregation between F. crassa and S. lessoni results from highly asymmetric interference competition in the use of shelters. The presence of F. crassa reduced the use of crevices and growth rates of S. lessoni. Effects on growth rates are assumed to result from exposure to harsh environmental conditions rather than food limitation. Thus, neither gregarious behaviour nor differences in activity were sufficient to prevent competition with the larger grazer. Our study illustrates the importance of competition for shelters, which results in behavioural changes of the smaller-sized species, and how these plastic responses can translate into differences in growth rates. Use of shelters can thus be modulated by environmental conditions in a species-specific as well as an interactive manner within consumers’ guilds.
Año: 2012
Palabras claves: Foraging, Shelters, Herbivory, Physiological parameters, Species interactions, Trophic interactions, Food, Predation.
Referencia APA: Aguilera, M. & Navarrete, S. (2012). Interspecific Competition for Shelters in Territorial and Gregarious Intertidal Grazers: Consequences for Individual Behaviour. Plos ONE, 7(9), e46205.
Application of water quality indices and analysis of the surface water quality monitoring network in semiarid North-Central Chile
Espejo, L., Kretschmer, N., Oyarzún, J., Meza, F., Núñez, J., Maturana, H., Soto, G., Oyarzo, P., Garrido, M., Suckel, F., Amezaga, J., Oyarzún, R.
Surface water quality has increasing importance worldwide and is particularly relevant in the semiarid North-Central Chile, where agriculture and mining activities are imposing heavy pressure on limited water resources. The current study presents the application of a water quality index in four watersheds of the 29°–33°S realm for the period 1999–2008, based on the Canadian Council of Ministers for the Environment approach and the Chilean regulation for irrigation water quality. In addition, two modifications to the index are tested and a comprehensive characterization of the existing monitoring network is performed through cluster analysis. The basins studied show fairly good water quality in the overall, specially the Limarí basin. On the other hand, the lower index values were obtained for the headwaters of Elqui, associated with the El Indio mining district. The first modification of the indicator (i.e., to consider parameters differentially according to their effect on human health or the environment) did not produce major differences with respect to the original index, given the generally good water quality. The second modification (i.e., to consider as threshold values the more restrictive figures derived from a set of regulations) yielded important differences in the indicator values. Finally, an adequate characterization of the monitoring network was obtained. The results presented spatial coherence and the information can be used as a basis for the optimization of the monitoring network if required.
Año: 2012
Palabras claves: CCME-WQI, Secondary water quality regulations, Physicochemical parameters, Heavy metals, Cluster analysis.
Referencia APA: Espejo, L., Kretschmer, N., Oyarzún, J., Meza, F., Núñez, J., & Maturana, H. et al. (2012). Application of water quality indices and analysis of the surface water quality monitoring network in semiarid North-Central Chile. Environmental Monitoring And Assessment, 184(9), 5571-5588.
Physiological performance of juvenile Haliotis rufescens and Haliotis discus hannai abalone exposed to the withering syndrome agent.
González, R., Brokordt, K., & Lohrmann, K.
Withering syndrome (WS) is a serious chronic disease caused by infection with the bacterium Candidatus Xenohaliotis californiensis, a Rickettsiales-like organism (WS-RLO) that affects multiple abalone species in both natural and farmed populations. However, there is no available information regarding the effects of this disease on the physiological performance of infected abalone. We studied the effect of different levels of infection on components of energy balance and physiological indices (rates of absorption and assimilation, O/N ratio, and scope for growth) in the abalone species Haliotis rufescens and Haliotis discus hannai. Juveniles were exposed to C. X. californiensis transmission for 130 days, during which time the presence/absence of WS-RLOs was evaluated by PCR (following DNA sequencing-based confirmation of 100% identity with the sequence of C. X. californiensis from California), and the prevalence and intensity of infection were evaluated via histological analysis. Among H. rufescens juveniles exposed to the bacterium, 92% became infected (positive by histology), and the intensity of infection ranged from low (degree 1) to moderate (degree 2). In contrast, no H. discus hannai juveniles were positive for WS-RLO by histology, although 23% were positive by PCR, possibly indicating incipient WS-RLO infection that did not develop during the experimental period or to mere presence of WS-RLO DNA in the sample. Infection of H. rufescens juveniles by WS-RLOs negatively affected all components of the energy balance and physiological indices, such as scope for growth and the O/N ratio, in direct relation to the degree of infection. The most strongly affected functions were the rate of ingestion, standard metabolism, and production of feces, which were reduced by 60–80% in the most highly infected individuals. The reduced energy intake in the organisms produced a strong energy imbalance such that the energy available for growth was reduced by 49% in infected organisms. In contrast, juveniles of H. discus hannai carrying the bacterium developed no infection and showed no alterations of physiological function. Our results indicate that the level of early infection by WS-RLOs may exert a negative effect on physiological activity in H. rufescens, even when the disease is not evident.
Año: 2012
Palabras claves: Withering syndrome; Candidatus Xenohaliotis californiensis; Abalone; Haliotis rufescens; Haliotis discus hannai; Physiological performance
Referencia APA: González, R., Brokordt, K., & Lohrmann, K. (2012). Physiological performance of juvenile Haliotis rufescens and Haliotis discus hannai abalone exposed to the withering syndrome agent. Journal Of Invertebrate Pathology, 111(1), 20-26.
Postglacial vegetation, fire and climate dynamics at Central Chilean Patagonia (Lake Shaman, 44°S).
de Porras, M., Maldonado, A., Abarzúa, A., Cárdenas, M., Francois, J., & Martel-Cea, A. et al.
A 19 cal ka BP pollen and charcoal record from Lake Shaman (44°S; 71°W, Chile) was analyzed to establish vegetation, fire and climate dynamics of the forest-steppe ecotone in Central Chilean Patagonia. Lake Shaman record indicates that the upper Río Cisnes valley was free of ice at around 19 cal ka BP. From this date and until 14.8 cal ka BP, a grass steppe with high proportions of shrubs associated to colder and drier conditions than present developed in this area. A continuous increase of Nothofagus accompanied by a decline in the steppe shrubs and sudden dominance of paludal over aquatic plants from 11 cal ka BP was associated to effective moisture increase but still under modern values. The replacement of the cold-dry grass-shrub steppe by a similar-than-present forest-steppe ecotone suggests an increase in temperature indicating the onset of the Holocene. At the same time, moderate fire activity suggested by the charcoal record could be related to major fuel availability as consequence of Nothofagus forest expansion. Between 8 and 3 cal ka BP, the record indicates the easternmost position of the forest-steppe ecotone suggesting the highest effective moisture with the establishment of seasonality between 5 and 3 cal ka BP. From 3 cal ka BP, the record indicates a retraction of the forest-steppe ecotone accompanied by a high pollen record variability and an increased fire activity. These late changes suggest decreased effective moisture associated with a high climatic variability. At regional and extra-regional scale, climatic changes at Lake Shaman's record are mostly associated to changes (latitudinal shifts and/or strengthening/weakening) of past Southern Westerlies that were previously recorded along Patagonia from the Lateglacial to the mid-Holocene. During the Late Holocene, a regional pattern characterized by high record variability emerges throughout Central Chilean Patagonia. This variability would be related to (1) low magnitude Southern Westerlies changes probably associated to ENSO and/or SAM or (2) the complex relationships between vegetation, fire and human occupations during the last 3 cal ka.
Año: 2012
Palabras claves: Forest-steppe ecotone; Central Chilean Patagonia; Southern Westerlies; Lateglacial
Referencia APA: de Porras, M., Maldonado, A., Abarzúa, A., Cárdenas, M., Francois, J., & Martel-Cea, A. et al. (2012). Postglacial vegetation, fire and climate dynamics at Central Chilean Patagonia (Lake Shaman, 44°S). Quaternary Science Reviews, 50, 71-85.
Temporal variability of incidental solar radiation and modulating factors in a coastal upwelling area (36°S).
Hernández, K., Yannicelli, B., Montecinos, A., Ramos, M., González, H., & Daneri, G.
In this study, we quantify the annual and synoptic variability of solar radiation (PAR and UVR) for southern-central Chile at ∼36.5°S from 2003 to 2004 and we relate these fluctuations to total ozone concentration, cloudiness, and winds. Data considered approximately 2 years of daily visible PAR (400–700 nm), UVA (400–320 nm), and UVB (280–320 nm). Satellite ozone data were also compared with a 305/340 ratio. On an annual scale, the visible and UV radiation co-varied in phase, with maxima in spring–summer and lower values in autumn–winter. Winds and cloudiness also showed an annual cycle, with predominantly southerly winds and lower cloudiness in summer. On a synoptic scale, solar radiation was coupled with cloudiness and winds, a relationship that is also evidenced over large scale atmospheric circulation. A 3-month lag was observed between solar radiation and ozone annual cycles; the latter peaked in springtime. The 305/340 ratio was a good ozone index over short time scales, showing fluctuations at the same frequencies as ozone and good cross-correlations once the annual cycle was extracted. The spatial–temporal analysis supports the possibility that the local pattern observed might be common for other important upwelling sites affected by the same type of atmospheric variability. Finally, this study showed that solar radiation wavelengths fluctuating at similar frequencies as those of upwelling favorable winds, are likely to be modulating biological processes in the coastal upwelling area off Concepción over short time scales.
Año: 2012
Palabras claves:
Referencia APA: Hernández, K., Yannicelli, B., Montecinos, A., Ramos, M., González, H., & Daneri, G. (2012). Temporal variability of incidental solar radiation and modulating factors in a coastal upwelling area (36°S). Progress In Oceanography, 92-95, 18-32.
Emergence of social complexity among coastal hunter-gatherers in the Atacama Desert of northern Chile.
Marquet, P., Santoro, C., Latorre, C., Standen, V., Abades, S., & Rivadeneira, M. et al.
The emergence of complex cultural practices in simple hunter-gatherer groups poses interesting questions on what drives social complexity and what causes the emergence and disappearance of cultural innovations. Here we analyze the conditions that underlie the emergence of artificial mummification in the Chinchorro culture in the coastal Atacama Desert in northern Chile and southern Peru. We provide empirical and theoretical evidence that artificial mummification appeared during a period of increased coastal freshwater availability and marine productivity, which caused an increase in human population size and accelerated the emergence of cultural innovations, as predicted by recent models of cultural and technological evolution. Under a scenario of increasing population size and extreme aridity (with little or no decomposition of corpses) a simple demographic model shows that dead individuals may have become a significant part of the landscape, creating the conditions for the manipulation of the dead that led to the emergence of complex mortuary practices.
Año: 2012
Palabras claves: climate variability, coastal desert, cultural evolution
Referencia APA: Marquet, P., Santoro, C., Latorre, C., Standen, V., Abades, S., & Rivadeneira, M. et al. (2012). Emergence of social complexity among coastal hunter-gatherers in the Atacama Desert of northern Chile. Proceedings Of The National Academy Of Sciences, 109(37), 14754-14760. http://dx.doi.org/10.1073/pnas.1116724109
Plasticidad fenotípica en dos poblaciones antárticas de Colobanthus quitensis (Caryophyllaceae) bajo un escenario simulado de cambio global
Molina-Montenegro, M., Torres-Díaz, C., Carrasco-Urra, F., González-Silvestre, L., & Gianoli, E.
La Antártica se caracteriza por presentar condiciones ambientales extremas, lo cual limita el establecimiento de las plantas vasculares. Dentro de dichas características ambientales están las bajas temperaturas, corta estación de crecimiento y el estrés hídrico y nutricional. La baja disponibilidad hídrica ha sido sugerida como la principal limitante para el éxito de establecimiento, debido a que afecta de manera negativa las respuestas fisiológicas y reproductivas de las plantas. Colobanthus quitensis (Kunth) Bartl. (Caryophyllaceae) es una de las dos plantas vasculares nativas que habitan la Antártica Marítima y se ha demostrado que su desempeño fisiológico y reclutamiento es afectado negativamente por el estrés hídrico del suelo. La plasticidad fenotípica y la adaptación local serían dos de las principales estrategias de C. quitensis para lidiar con las adversas condiciones ambientales que predominan en el continente antártico. Se ha documentado que, bajo un escenario futuro de cambio climático, la disponibilidad hídrica en la Antártica aumentaría entre un 30-40%, mejorando las condiciones para el establecimiento. En el presente trabajo evaluamos mediante un experimento de jardín común, realizado en cámaras de crecimiento, la plasticidad morfo-fisiológica y el esfuerzo reproductivo en individuos de C. quitensis provenientes de dos sitios en las Islas Shetland, bajo un escenario simulado de cambio climático (aumento en un 40% de la disponibilidad hídrica) y bajo la situación actual (disponibilidad hídrica registrada en los sitios de origen). En general, los individuos de C. quitensis de ambos sitios presentaron evidencia de plasticidad, aumentando su eficiencia fotoquímica, largo y ancho foliar, y esfuerzo reproductivo bajo la condición de aumento en la disponibilidad hídrica. La magnitud del aumento en la respuesta plástica fue mayor en aquellos individuos provenientes del sitio más árido en comparación a sus con-específicos del sitio más húmedo. Si los actuales patrones de cambio climático se mantienen, las condiciones abióticas podrían volverse más favorables para C. quitensis, mejorando su desempeño ecofisiológico y permitiendo la expansión de su rango de distribución sobre la Antártica.
Año: 2012
Palabras claves: Antártica, esfuerzo reproductivo, estrés hídrico, Fv / Fm, islas Shetland.
Referencia APA: Molina-Montenegro, M., Torres-Díaz, C., Carrasco-Urra, F., González-Silvestre, L., & Gianoli, E. (2012). Plasticidad fenotípica en dos poblaciones antárticas de Colobanthus quitensis (Caryophyllaceae) bajo un escenario simulado de cambio global. Gayana Bot., 69(1), 152-160.
Cold-acclimation limits low temperature induced photoinhibition by promoting a higher photochemical quantum yield and a more effective PSII restoration in darkness in the Antarctic rather than the Andean ecotype of Colobanthus quitensis Kunt Bartl (Cariophyllaceae)
Bascuñán-Godoy, L., Sanhueza, C., Cuba, M., Zuñiga, G., Corcuera, L., & Bravo, L.
Ecotypes of Colobanthus quitensis Kunt Bartl (Cariophyllaceae) from Andes Mountains and Maritime Antarctic grow under contrasting photoinhibitory conditions, reaching differential cold tolerance upon cold acclimation. Photoinhibition depends on the extent of photodamage and recovery capability. We propose that cold acclimation increases resistance to low-temperature-induced photoinhibition, limiting photodamage and promoting recovery under cold. Therefore, the Antarctic ecotype (cold hardiest) should be less photoinhibited and have better recovery from low-temperature-induced photoinhibition than the Andean ecotype. Both ecotypes were exposed to cold induced photoinhibitory treatment (PhT). Photoinhibition and recovery of photosystem II (PSII) was followed by fluorescence, CO2 exchange, and immunoblotting analyses.
Año: 2012
Palabras claves: Antarctic plants, Andean plants, Cold-induced-photoinhibition, Recovery, PSII restoration, D1 cycle, Photoprotection
Referencia APA: Bascuñán-Godoy, L., Sanhueza, C., Cuba, M., Zuñiga, G., Corcuera, L., & Bravo, L. (2012). Cold-acclimation limits low temperature induced photoinhibition by promoting a higher photochemical quantum yield and a more effective PSII restoration in darkness in the Antarctic rather than the Andean ecotype of Colobanthus quitensis Kunt Bartl (Cariophyllaceae). BMC Plant Biol, 12(1), 114.
Occurrence of the Non-Native Annual Bluegrass on the Antarctic Mainland and Its Negative Effects on Native Plants.
Molina-Montenegro, M., Carrasco-Urra, F., Rodrigo, C., Convey, P., Valladares, F., & Gianoli, E.
Few non-native species have colonized Antarctica, although increased human activity and accelerated climate change may increase their number, distributional range, and effects on native species on the continent. We searched 13 sites on the maritime Antarctic islands and 12 sites on the Antarctic Peninsula for annual bluegrass (Poa annua), a non-native flowering plant. We also evaluated the possible effects of competition between P. annua and 2 vascular plants native to Antarctica, Antarctic pearlwort (Colobanthus quitensis) and Antarctic hairgrass (Deschampsia antarctica). We grew the native species in experimental plots with and without annual bluegrass under conditions that mimicked the Antarctic environment. After 5 months, we measured photosynthetic performance on the basis of chlorophyll fluorescence and determined total biomass of both native species. We found individual specimens of annual bluegrass at 3 different sites on the Antarctic Peninsula during the 2007–2008 and 2009–2010 austral summers. The presence of bluegrass was associated with a statistically significant reduction in biomass of pearlwort and hairgrass, whereas the decrease in biomass of bluegrass was not statistically significant. Similarly, the presence of bluegrass significantly reduced the photosynthetic performance of the 2 native species. Sites where bluegrass occurred were close to major maritime routes of scientific expeditions and of tourist cruises to Antarctica. We believe that if current levels of human activity and regional warming persist, more non-native plant species are likely to colonize the Antarctic and may affect native species.
Año: 2012
Palabras claves: Colobanthus quitensis;Deschampsia antarctica;hairgrass;non-native species;pearlwort;species competition;tourism;Poa annuaColobanthus quitensis;competencia de especies;Deschampsia antarctica;especie no nativa;Poa annua;turismo
Referencia APA: Molina-Montenegro, M., Carrasco-Urra, F., Rodrigo, C., Convey, P., Valladares, F., & Gianoli, E. (2012). Occurrence of the Non-Native Annual Bluegrass on the Antarctic Mainland and Its Negative Effects on Native Plants. Conservation Biology, 26(4), 717-723.
Linking Climatic Variability with Spatial Performance in Two Varieties of Quinoa Distributed in a Semi-Arid Zone.
Montecinos, S., Salinas, P., Oses, R., González-Silvestre, L., & Molina-Montenegro, M.
Different crop varieties can respond in different ways to the climatic variations at local scale. Thus, in order to maximize
the yield for a determined crop, the response of different varieties submitted to local climatic conditions should be
assessed. The main goal of this study was to evaluate the ecophysiological responses of two varieties of Quinoa (PRP
and BO78) submitted to different conditions of thermal amplitude. We performed two experiments in both greenhouse
and in 3 sites on experimental-field where were evaluated survival, photochemical efficiency, plant growth and dry
biomass in both varieties and compared them with the mean of the thermal conditions recorded during the last 16 years
in the Coquimbo Region, Chile. Overall, individuals of BO78 showed higher performance in the sites with lower thermal
amplitude than those of PRP. By contrast, in sites with higher thermal amplitude individuals of PRP showed better
survival, physiological performance and biomass and therefore higher performance. Our results suggest that while
BO78 showed an ecotypic strategy, the PRP showed a plastic strategy to maintain higher performance in sites with
moderate and high climatic variability. We consider that under an increase in desertification, semi-arid areas would be
available for stress tolerant crops like Quinoa, but the success for the food security in these regions may depend upon
the variety used.
Año: 2012
Palabras claves: Quinoa; Thermal Amplitude; Plasticity; Ecophysiology; Crop Yield
Referencia APA: Montecinos, S., Salinas, P., Oses, R., González-Silvestre, L., & Molina-Montenegro, M. (2012). Linking Climatic Variability with Spatial Performance in Two Varieties of Quinoa Distributed in a Semi-Arid Zone. AJPS, 03(12), 1682-1687.
Latitudinal Patterns in Phenotypic Plasticity and Fitness-Related Traits: Assessing the Climatic Variability Hypothesis (CVH) with an Invasive Plant Species.
Molina-Montenegro, M. & Naya, D.
Phenotypic plasticity has been suggested as the main mechanism for species persistence under a global change scenario, and also as one of the main mechanisms that alien species use to tolerate and invade broad geographic areas. However, contrasting with this central role of phenotypic plasticity, standard models aimed to predict the effect of climatic change on species distributions do not allow for the inclusion of differences in plastic responses among populations. In this context, the climatic variability hypothesis (CVH), which states that higher thermal variability at higher latitudes should determine an increase in phenotypic plasticity with latitude, could be considered a timely and promising hypothesis. Accordingly, in this study we evaluated, for the first time in a plant species (Taraxacum officinale), the prediction of the CVH. Specifically, we measured plastic responses at different environmental temperatures (5 and 20°C), in several ecophysiological and fitness-related traits for five populations distributed along a broad latitudinal gradient. Overall, phenotypic plasticity increased with latitude for all six traits analyzed, and mean trait values increased with latitude at both experimental temperatures, the change was noticeably greater at 20° than at 5°C. Our results suggest that the positive relationship found between phenotypic plasticity and geographic latitude could have very deep implications on future species persistence and invasion processes under a scenario of climate change.
Año: 2012
Palabras claves: Biogeography, Latitude, Invasive species, Phenotypes, Climate change, Seeds, Photosynthetic efficiency, Plants.
Referencia APA: Molina-Montenegro, M. & Naya, D. (2012). Latitudinal Patterns in Phenotypic Plasticity and Fitness-Related Traits: Assessing the Climatic Variability Hypothesis (CVH) with an Invasive Plant Species. Plos ONE, 7(10), e47620.