Temporal variability of incidental solar radiation and modulating factors in a coastal upwelling area (36°S).

Autores:

Hernández, K., Yannicelli, B., Montecinos, A., Ramos, M., González, H., & Daneri, G.

Resumen:

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:

Upwelling response to atmospheric coastal jets off central Chile: A modeling study of the October 2000 event.

Autores:

Renault, L., Dewitte, B., Marchesiello, P., Illig, S., Echevin, V., & Cambon, G., Ramos, M., Astudillo, O., Minnis, P., Ayers, J.K.

Resumen:

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

Inter-annual variability of southerly winds in a coastal area of the Atacama Desert: implications for the export of aeolian sediments to the adjacent marine environment.

Autores:

Flores-Aqueveque, V., Alfaro, S., Caquineau, S., Foret, G., Vargas, G., & Rutllant, J.

Resumen:

The analysis of the aeolian content of marine cores collected off the coast of the Atacama Desert (Mejillones Bay, Chile) suggests that marine sediments can record inter-annual to inter-decadal variations in the regional southerly winds responsible for particle entrainment at the surface of the nearby desert. However, the establishment of a simple and direct correlation between the sediment and wind records is complicated by the difference of time scales between the erosion and accumulation processes. The aim of this work is to: (i) assess the inter-annual variability of the surface winds responsible for the sand movements; and (ii) determine whether the integration over periods of several months completely smoothes the rapid changes in characteristics of the transported and deposited aeolian material. To accomplish this aim, 14 years of 10 m hourly wind speed, measured at the Cerro Moreno (Antofagasta) Airport between 1991 and 2003 and at the Orica Station between 2000 and 2004, were analyzed. For each year, the wind speed statistical distribution can be represented by a combination of two to three Weibull functions. Winds of the lowest Weibull mode are too weak to move the sand grains at the surface of the pampa; this is not the case for the intermediate mode and especially for the highest speed mode which are able to erode the arid surface and transport particles to the bay. In each individual year of the period of study, the highest speed mode only accounted for a limited number of strong erosion events. Quantitative analysis of the distribution of the friction velocities and of their impact on erosion using a saltation model suggests that, although all wind speeds above threshold produce erosion events, values around 0·45 m sec−1 contribute less to the erosion flux. This gap allows separation of the erosion events into low and high saltation modes. The correlation (r = 0·997) between the importance of the third Weibull mode and the extent of higher rate saltation indicates that the inter-annual variability of the erosion at the surface of the pampa, as well as the transport of coarse particles (>100 μm), are directly related to inter-annual variations in the prevalence of the strongest winds. Finally, a transport and deposition model is used to assess the possible impact of the wind inter-annual variability on the deposition flux of mineral particles in the bay. The results suggest that inter-annual differences in the wind speed distributions have a quantifiable effect on the intensity and size-distribution of this deposition flux. This observation suggests that a detailed analysis of the sediment cores collected from the bay could be used for reconstructing the inter-annual variability of past winds.

Año: 2012

Palabras claves: Atacama Desert; dust transport and deposition; wind erosion; wind variability.

Lizards on Ice: Evidence for Multiple Refugia in Liolaemus pictus (Liolaemidae) during the Last Glacial Maximum in the Southern Andean Beech Forests.

Autores:

Vera-Escalona, I., D'Elía, G., Gouin, N., Fontanella, F., Muñoz-Mendoza, C., Sites, J., & Victoriano, P.

Resumen:

Historical climate changes and orogenesis are two important factors that have shaped intraspecific biodiversity patterns worldwide. Although southern South America has experienced such complex events, there is a paucity of studies examining the effects on intraspecific diversification in this part of the world. Liolaemus pictus is the southernmost distributed lizard in the Chilean temperate forest, whose genetic structure has likely been influenced by Pleistocene glaciations. We conducted a phylogeographic study of L. pictus in Chile and Argentina based on one mitochondrial and two nuclear genes recovering two strongly divergent groups, Northern and Southern clades. The first group is distributed from the northernmost limit of the species to the Araucanía region while the second group is distributed throughout the Andes and the Chiloé archipelago in Southern Chile. Our results suggest that L. pictus originated 751 Kya, with divergence between the two clades occurring in the late Pleistocene. Demographic reconstructions for the Northern and Southern clades indicate a decrease in effective population sizes likely associated with Pleistocene glaciations. Surprisingly, patterns of genetic variation, clades age and historical gene flow in populations distributed within the limits of the Last Glacial Maximum (LGM) are not explained by recent colonization. We propose an “intra-Andean multiple refuge” hypothesis, along with the classical refuge hypothesis previously proposed for the biota of the Chilean Coastal range and Eastern Andean Cordillera. Our hypothesis is supported by niche modelling analysis suggesting the persistence of fragments of suitable habitat for the species within the limits of the LGM ice shield. This type of refuge hypothesis is proposed for the first time for an ectothermic species.

Año: 2012

Palabras claves: Haplotypes, Phylogeography, Gene flow, Chile (country), Phylogenetic analysis, Population genetics, Mitochondrial DNA, Mitochondria.

Genetic diversity and comparison of physicochemical and nutritional characteristics of six quinoa (Chenopodium quinoa willd.) genotypes cultivated in Chile.

Autores:

Miranda, M., Vega-Gálvez, A., Martinez, E., López, J., Rodríguez, M., Henríquez, K., & Fuentes, F.

Resumen:

The present study was focused on the analysis of agronomical, nutritional, physicochemical, and antioxidant properties of six genetically different quinoa (Chenopodium quinoa Willd) genotypes cultivated in three distinctive geographical zones of Chile. Ancovinto and Cancosa genotypes from the northern Altiplano (19 ºS), Cáhuil and Faro from the central region (34 ºS), and Regalona and Villarica from the southern region (39 ºS) are representative of high genetic differentiation among the pooled samples, in particular between Altiplano and the central-southern groups. A Common-Garden Assay at 30 ºS showed significant differences among seed origins in all morphometric parameters and also in yields. Altiplano genotypes had larger panicule length but no seed production. A significant influence of the different quinoa genotypes on chemical composition and functional properties was also observed. Protein concentration ranged from 11.13 to 16.18 g.100 g–1 d.m., while total dietary fiber content ranged from 8.07-12.08 g.100 g–1 d.m., and both were the highest in Villarrica ecotype. An adequate balance of essential amino acids was also observed. Sucrose was the predominant sugar in all genotypes. Antioxidant activity was high in all genotypes, and it was highest in Faro genotype (79.58% inhibition).

Año: 2012

Palabras claves: quinoa; antioxidant activity; amino acids; functional properties.

A three-year mark-recapture study in a remnant population of Crocodylus acutus Cuvier in Portete Bay (Guajira, Colombia).

Autores:

Espinosa, M., Bertin, A., Gómez, J., Mejía, F., Guerra, M., & Baez, L., Gouin, N., Patiño, E.

Resumen:

El Cocodrilo Americano Crocodylus acutus, ha experimentado importantes declines poblacionales a lo amplio de su distribución debido a la persecución humana, la sobreexplotación y la pérdida de hábitat. C. acutus permanece en peligro crítico en algunos países tales como Colombia donde la ausencia de estudios detallados sobre su ecología y distribución constituyen una de las barreras principales para el desarrollo de efectivas estrategias de conservación. Durante tres años desarrollamos un estudio de captura-recaptura para investigar el estatus demográfico de C. acutus e identificar las variables medioambientales más influyentes en su distribución en Bahía Portete (Colombia). Nosotros estimamos que la población de cocodrilos es relativamente pequeña (< 140 animales), incluye muy pocos adultos y demuestra un fuerte déficit de hembras en la clase juvenil. La humedad relativa y la temperatura promedio del aire estuvieron positivamente correlacionadas con el número de avistamientos de cocodrilos. Por el contrario, la salinidad promedio del agua se encontró relacionada con la baja probabilidad de observación, presumiblemente debido a la preferencia de los juveniles por áreas de baja salinidad. Nuestros resultados sugieren que la población de C. acutus en Bahía Portete está en riesgo y puede requerir la intervención humana para asegurar su persistencia.

Año: 2012

Palabras claves: Captura-recaptura, cocodrilo, variables medioambientales, manglar

The role of spatial processes and environmental determinants in microgeographic shell variation of the freshwater snail Chilina dombeyana (Bruguière, 1789).

Autores:

Bertin, A., Ruíz, V., Figueroa, R., & Gouin, N.

Resumen:

Wildlife data often show spatial organization, demonstrating positive correlations either as a result of processes occurring over the landscape or due to the influence of spatially structured environmental variables. It is, thus, essential to consider non-random spatial structure when evaluating the underlying causes of biological variation. In this study, we analyzed the population structure of Chilina dombeyana shell morphology of 14 populations that are close geographically and belong to the same hydrographic basin. We utilized a variation partitioning approach to evaluate the importance of spatial processes, such as migration, acting over the landscape, and environmental characteristics, including habitat and hydrologic characteristics, and the occurrence of aquatic predators in promoting between population variation. Our results demonstrate spatially structured variation in C. dombeyana shell morphology, with populations living near each other having more similar shell sizes than populations living farther apart. The shell size variation partition indicated that both spatially structured environmental factors and genetic relationships resulting from migration or shared common ancestry may explain this pattern. Shell shape variation, in contrast, was found to be essentially under the influence of non-spatially structured environmental factors, with habitat and water characteristics accounting for about half of the total variation among populations. The large proportion of the variation in shell size that is spatially structured demonstrates that spatial structure on morphological traits might be strong and highlights the need to consider such phenomenon in intraspecific studies of phenotypic evolution.

Año: 2012

Palabras claves: Shape, Size, Environmental factors, Spatial structure, Gastropod, Variation partition, Lotic environment

Isolation of microsatellite markers for two Chilean freshwater anomuran species (Aegla araucaniensis and Aegla pewenchae) using PCR-based methods.

Autores:

Gouin, N., Bórquez, J., Samollow, P., Douglas, K., Jasti, M., & Bertin, A.

Resumen:

We developed ten polymorphic microsatellite markers for two species of freshwater anomura endemic to Chile, Aegla araucaniensis and Aegla pewenchae, using two PCR-based methods, PIMA and ISSR-PCR. Nine markers per species gave useful PCR products, revealing moderate to high levels of genetic variation. The number of alleles per locus ranged from 2 to 13 and the observed heterozygosity from 0.103 to 0.929. All the markers appeared to segregate independently. No departure from Hardy–Weinberg equilibrium was found in A. araucaniensis while three markers showed evidence for deficits of heterozygotes and presence of null alleles in A. pewenchae. These markers will be useful for population genetics analyses.

Año: 2012

Palabras claves: Aeglidae, Crustacean, Microsatellite, PIMA, ISSR-PCR, Population genetics.

Effects of high hydrostatic pressure on microstructure, texture, colour and biochemical changes of red abalone (Haliotis rufecens) during cold storage time.

Autores:

Briones-Labarca, V., Perez-Won, M., Zamarca, M., Aguilera-Radic, J., & Tabilo-Munizaga, G.

Resumen:

This study was carried out to evaluate the effect of high hydrostatic pressure on quality changes (microstructure, colour, texture and biochemical) of red abalone (Haliotis rufecens) during storage time at 4 °C. High hydrostatic pressure (HHP) treatments were applied at 500 MPa for 8 min and 550 MPa for 3 and 5 min. Biochemical indices covering pH, total volatile basic nitrogen (TVB-N) and trimethylamine (TMA), as well as instrumental texture, microstructure and colour of abalone samples were determined immediately after treatment and throughout subsequent storage at 4 °C. Results have shown that HHP-treated abalones have significantly (p ≤ 0.05) higher pH, moisture and ash content than untreated abalones. Protein and fat contents of treated abalones were significantly (p ≤ 0.05) lower compared to untreated sample (control). TVB-N and TMA levels for HHP-treated abalones rose over the storage period but did not exceed 28 mg TVB-N/100 g and 3 mg TMA/100 g, respectively at the end of 60 days. Instead, the untreated sample exceeded the allowed limit in a 30 day period for the TVB-N and TMA. However, all HHP treatments had less negative effects on tissue colour of abalone than untreated samples in the cold storage time; moreover, whiteness index was reduced to 8% at the end of day 60. A more compact structure was identified as high hydrostatic pressure was higher. Thus, it was concluded that holes in muscle fibres were often due to protein gelation, whenever pressure and protein concentration are high enough, confirming that the structure of abalone muscle treated with high hydrostatic pressure differed significantly from that of raw abalone meat.

Año: 2012

Palabras claves: High hydrostatic pressure; Abalone; Colour; pH; TVB-N; TMA; Microstructure

Effect of high pressure on the interactions of myofibrillar proteins from abalone (Haliotis rufencens) containing several food additives.

Autores:

Barrios-Peralta, P., Pérez-Won, M., Tabilo-Munizaga, G., & Briones-Labarca, V.

Resumen:

Changes induced by high hydrostatic pressure (HHP) processing on the chemical and functional properties of seafood proteins and their interactions with selected food additives, such as potato starch (PS), dried egg whites (EW) and agar, were studied at pressures ranging from 200 to 550 MPa for 3, 5 and 10 min. Phosphate buffers were used to extract abalone muscle myofibrillar proteins. Protein changes was studied by UV–visible spectroscopy and functionality by their emulsifying capacity. The results show changes in peak heights and the appearance of new peaks at 327 nm in pressurised samples with additives; however, interactions between myofibrillar proteins and food additives did not take place, the same was observed by SDS-PAGE, regardless of the pressure treatment applied. In contrast, the emulsifying capacity increased in samples with agar and PS treated at 350–550 MPa. The highest emulsifying capacity was obtained in samples with 4 g PS/100 mL of protein dilution at 450 MPa for 5 min, while the emulsifying capacity decreased at 200 MPa using 10 g EW/100 mL of protein. No changes in protein bands were observed for all samples, suggesting that high pressure did not influence changes in the molecular weights of the proteins.

Año: 2012

Palabras claves: Myofibrillar protein; High hydrostatic pressure; Starch; Agar; Abalone.