CEAZA
Functional identity and functional structure change through succession in a rocky intertidal marine herbivore assemblage.
Aguilera, M. & Navarrete, S.
Despite the great interest in characterizing the functional structure and resilience of functional groups in natural communities, few studies have examined in which way the roles and relationships of coexisting species change during community succession, a fundamental and natural process that follows the release of new resources in terrestrial and aquatic ecosystems. Variation in algal traits that characterize different phases and stages of community succession on rocky shores are likely to influence the magnitude, direction of effects, and the level of redundancy and complementarity in the diverse assemblage of herbivores. Two separate field experiments were conducted to quantify per capita and population effects and the functional relationship (i.e., redundancy or complementarity) of four herbivore species found in central Chile during early and late algal succession. The first experiment examined grazer effects on the colonization and establishment of early-succession algal species. The second experiment examined effects on the late-successional, dominant corticated alga Mazzaella laminarioides. Complementary laboratory experiments with all species and under natural environmental conditions allowed us to further characterize the collective effects of these species. We found that, during early community succession, all herbivore species had similar effects on the ephemeral algae, ulvoids, but only during the phase of colonization. Once these algae were established, only a subset of the species was able to control their abundance. During late succession, only the keyhole limpet Fissurella crassa could control corticated Mazzaella. The functional relationships among these species changed dramatically from redundant effects on ephemeral algae during early colonization, to a more complementary role on established early-successional algae, to a dominant (i.e., keystone) effect on late succession. This study highlights that functional relationship within consumer assemblages can vary at different phases and times of community succession. Differentiation in herbivore roles emphasizes the need to evaluate consumer's impacts through different times of community succession, and through experimental manipulations to make even broad predictions about the resilience or vulnerability of diverse intertidal assemblages to human disturbances.
Año: 2012
Palabras claves: Chile; ephemeral algae; functional redundancy; functional roles; grazing; herbivores; human impact; interaction strength; keystone species; rocky shore
Referencia APA: Aguilera, M. & Navarrete, S. (2012). Functional identity and functional structure change through succession in a rocky intertidal marine herbivore assemblage. Ecology, 93(1), 75-89. http://dx.doi.org/10.1890/11-0434.1
Recent melt rates of Canadian arctic ice caps are the highest in four millennia. Global And Planetary Change
Fisher, D., Zheng, J., Burgess, D., Zdanowicz, C., Kinnard, C., Sharp, M., & Bourgeois, J.
There has been a rapid acceleration in ice-cap melt rates over the last few decades across the entire Canadian Arctic. Present melt rates exceed the past rates for many millennia. New shallow cores at old sites bring their melt series up-to-date. The melt-percentage series from the Devon Island and Agassiz (Ellesmere Island) ice caps are well correlated with the Devon net mass balance and show a large increase in melt since the middle 1990s. Arctic ice core melt series (latitude range of 67 to 81 N) show the last quarter century has had the highest melt in two millennia and The Holocene-long Agassiz melt record shows that the last 25 years has the highest melt in 4200 years. The Agassiz melt rates since the middle 1990s resemble those of the early Holocene thermal maximum over 9000 years ago.
Año: 2012
Palabras claves: Ice core; Melt layers; Holocene; Warming; Ice caps
Referencia APA: Fisher, D., Zheng, J., Burgess, D., Zdanowicz, C., Kinnard, C., Sharp, M., & Bourgeois, J. (2012). Recent melt rates of Canadian arctic ice caps are the highest in four millennia. Global And Planetary Change, 84-85, 3-7.
Nutritional Aspects of Six Quinoa (Chenopodium quinoa Willd.) Ecotypes from three Geographical Areas of Chile. Chilean
Miranda, M., Vega-Gálvez, A., Quispe-Fuentes, I., Rodríguez, M., Maureira, H., & Martínez, E.
This study explored the diversity of the quinoa crop in Chile from a nutritional perspective. Nutritional properties, minerals, vitamins, and saponin content were assessed in seeds of six Chilean quinoa (Chenopodium quinoa Willd.) ecotypes grown in three main production areas with distinctive climatic and edaphic conditions: Ancovinto and Cancosa in the North-Altiplano or High Plateau, Cáhuil and Faro in the central coastal area, and Regalona and Villarrica in the south of the country. There were significant differences (P < 0.05) in all the nutritional properties of the quinoa seeds in all three areas. Quinoa of the Villarrica ecotype showed the highest protein content (16.10 g 100 g-1 DM) and the highest content of vitamins E and C (4.644 ± 0.240 and 23.065 ± 1.119 mg 100 g-1 DM, respectively). The highest content of vitamins B1 (0.648 ± 0.006 mg 100 g-1 DM) and B3 (1.569 ± 0.026 mg 100 g-1 DM) was found in the Regalona ecotype, while the highest value of vitamin B2 (0.081 ± 0.002 mg 100 g-1 DM) occurred in the Ancovinto ecotype. Potassium was the most abundant mineral with a maximum value of 2325.56 mg 100 g-1 DM in the Cancosa ecotype. Saponin content varied from 0.84 g 100 g-1 DM in the Villarrica ecotype to 3.91 g 100 g-1 DM in the Cáhuil ecotype. Significant differences were found among the Chilean quinoa ecotypes grown under different climatic conditions; however, all the quinoa seeds exhibited a high nutritional value. These results are compatible with the genetic differences previously observed in the three geographical areas under study. Thus, if more studies are conducted to show the particular properties of quinoa from specific areas, it would be possible in the future to coin the term "controlled designation of origin" (appellation d'origine contrólée) and add commercial value to Chilean quinoa seeds in the domestic and international markets.
Año: 2012
Palabras claves: Quinoa, vitamins, minerals, saponin content, nutritional properties.
Referencia APA: Miranda, M., Vega-Gálvez, A., Quispe-Fuentes, I., Rodríguez, M., Maureira, H., & Martínez, E. (2012). Nutritional Aspects of Six Quinoa (Chenopodium quinoa Willd.) Ecotypes from three Geographical Areas of Chile. Chilean. J. Agric. Res., 72(2), 175-181.
The trade-off between cold resistance and growth determines the Nothofagus pumilio treeline.
Molina-Montenegro, M., Gallardo-Cerda, J., Flores, T., & Atala, C.
The upper and poleward limit of tree distribution are usually determined by abiotic factors such as low temperature and strong winds. Thus, cold resistance is a key element for survival in high altitudes and latitudes where conditions can reduce plant growth. A trade-off between resource allocation to cold resistance and growth could emerge in populations frequently exposed to low temperatures like those in the treeline zone. We studied annual height growth and ice nucleation temperature in Nothofagus pumilio (Nothofagaceae) populations growing in its extremes of altitudinal distribution and in 3 sites situated on a latitudinal gradient in the Chilean Andes. Additionally, gas exchange, water and nitrogen use efficiency and total soluble sugar (TSS) were also measured as possible mechanisms for survival in high altitudes. Individuals from the treeline populations showed lower annual height growth and lower ice nucleation temperatures compared with those from lower populations. In the same way, individuals from more poleward populations showed lower annual height growth and lower ice nucleation temperatures. Gas exchange, water and nitrogen use efficiency and TSS were also higher in the high altitude populations. The results obtained support the hypothesis of trade-off, because the upper and poleward populations showed more cold resistance but a lower height growth. Additionally, we show that cold resistance mechanisms do not impact the physiological performance, suggesting possible adaptation of the high altitude populations. Low temperatures may be affecting cellular growth instead of photosynthesis, creating a pool of carbohydrates that could participate in cold tolerance. Other abiotic and biotic factors should be also assessed to fully understand the distributional range of Nothofagus species.
Año: 2012
Palabras claves: Height growth, Los Andes, Photosynthesis, Treeline, Environmental gradients, Ice nucleation.
Referencia APA: Molina-Montenegro, M., Gallardo-Cerda, J., Flores, T., & Atala, C. (2012). The trade-off between cold resistance and growth determines the Nothofagus pumilio treeline. Plant Ecol, 213(1), 133-142.
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.