CEAZA
Environmental Hypoxia Reduces the Escape Response Capacity of Juvenile and Adult Scallops Argopecten purpuratus.
Brokordt, K., Pérez, H., & Campos, F.
Natural beds and cultures of the scallop Argopecten purpuratus are exposed to hypoxia periodically because they are located near upwelling zones. We evaluated the effects of environmental hypoxia on juvenile and adult scallops' escape responses and recovery capacities using 3 different hypoxic cycle (i.e., a gradual decrease and increase of dissolved oxygen) trials. Trials 1 and 2 consisted of single (1-day) hypoxic cycles; trial 3 included exposure to several consecutive daily hypoxic cycles over 7 days, which occurs in the natural environment. Trial 1 evaluated the combined effects of energy demands from escape responses and metabolism on escape responses. during environmental hypoxia. Trial 2 evaluated only the effect of environmental hypoxia on the escape responses. Before and after the hypoxic cycles, the scallops were exposed to their main predator, the sea star Meyenaster gelatinosus. We evaluated 6 indicators of the scallops' escape response: reaction time, the total number of claps, duration of the clapping response until exhaustion, clapping speed, the proportion of claps, and recovery clapping rate after a recuperation of 5 min or 10 min (for juveniles and adults, respectively). The combined effect of functional and environmental hypoxia (trial 1) affected both juvenile and adult escape responses, with a reduction in their number of claps (15% and 25%, respectively), the clapping rate in juveniles (17%), and the clapping time in adults (19%). However, environmental hypoxia alone (trial 2) affected juvenile escape responses only, with a reduction in their number of claps (18%) and clapping rate (17%). After hypoxic exposure in trial 3, adults only showed a reduced escape capacity (clap number and clapping time of 16% and 17%, respectively), although both adult and juvenile scallops had a reduced capacity to recuperate their initial clap number (18% and 23%, respectively) and clapping rate (21% and 17%, respectively). Recovery capacity was associated with a strong reduction in phasic muscle carbohydrates during this period. Overall, hypoxia reduced the escape capacity of A. purpuratus, which may implicate a higher vulnerability to predation (for natural populations) and a decreased physiological status to support other stress factors (for cultured or natural populations).
Año: 2013
Palabras claves: Hypoxia, scallops, escape response, Argopecten purpuratus.
Referencia APA: Brokordt, K., Pérez, H., & Campos, F. (2013). Environmental Hypoxia Reduces the Escape Response Capacity of Juvenile and Adult Scallops Argopecten purpuratus. Journal Of Shellfish Research, 32(2), 369-376
Wind effects on snow cover in Pascua-Lama, Dry Andes of Chile.
Gascoin, S., Lhermitte, S., Kinnard, C., Bortels, K., & Liston, G.
We present the first application of a distributed snow model (SnowModel) in the instrumented site of Pascua-Lama in the Dry Andes (2600–5630 m above sea level, 29° S). A model experiment was performed to assess the effect of wind on the snow cover patterns. A particular objective was to evaluate the role of blowing snow on the glacier formation. The model was run using the data from 11 weather stations over a complete snow season. First, a cross-validation of the meteorological variables interpolation model (MicroMet submodel) was performed to evaluate the performance of the simulated meteorological forcing. Secondly, two SnowModel simulations were set up: one without and the other with the wind transport submodel (SnowTran-3D). Results from both simulations were compared with in situ snow depth measurements and remotely sensed snow cover data. The inclusion of SnowTran-3D does not change the fact that the model is unable to capture the small-scale snow depth spatial variability (as captured by in situ snow depth sensors). However, remote sensing data (MODIS daily snow product) indicate that at broader scales the wind module produced an improved representation of the snow distribution near the glaciers (2-D correlation coefficient increased from R = 0.04 to R = 0.27). The model outputs show that a key process is the sublimation of blowing snow, which amounts to 18% of the total ablation over the whole study area, with a high spatial variability. The effect of snow drift is more visible on the glaciers, where wind-transported snow accumulates preferentially. Net deposition occurred for 43% of the glacier grid points, whereas it is only 23% of non-glacier grid points located above the minimum glacier altitude (4475 m).
Año: 2013
Palabras claves: Snow; Glacier; Wind; Sublimation; Andes; MODIS.
Referencia APA: Gascoin, S., Lhermitte, S., Kinnard, C., Bortels, K., & Liston, G. (2013). Wind effects on snow cover in Pascua-Lama, Dry Andes of Chile. Advances In Water Resources, 55, 25-39.
Barotropic and baroclinic semidiurnal tidal currents in two contrasting coastal upwelling zones of Chile.
Bravo, L., Ramos, M., Sobarzo, M., Pizarro, O., & Valle-Levinson, A.
Current velocity observations from the continental shelves of Coquimbo (~30°S) and Concepcion (~36°30'S), central Chile, were analyzed to evaluate the role of water column stratification and shelf width on baroclinic semidiurnal tidal currents. Semidiurnal barotropic currents off both zones were typically < 5 cm/s, but depth-dependent semidiurnal flows could exceed 10 cm s-1 during stratified conditions. Both zones are recognized as pronounced upwelling centers, with maximum upwelling-favorable winds in spring and summer, respectively. At the northern zone, stratification was mainly controlled by temperature differences between surface and bottom waters with maximum stratification during summer. The southern zone showed more stratification during winter because of freshwater input from local rivers. Consequently, greater variability in the baroclinic semidiurnal currents was observed during summer at the northern continental shelf and in winter at the south. In both regions, much of the semidiurnal variability was consistent with an internal wave's first baroclinic mode of wavelengths of ~10–13 km. Nevertheless, during the period of maximum energy fluxes off the north, the second baroclinic mode (wavelength ~7 km) was also important and matched periods of low upwelling index (relaxation of upwelling favorable winds). Typical energy fluxes during summer integrated in the water column, related to the semidiurnal internal tides were 0.12 W/m of the northern site and 0.1 W/m off the southern site. Possible sites of internal wave generation off the south were the Biobío submarine canyon and the slope/shelf break, while off the north, the generation site was the slope/shelf break.
Año: 2013
Palabras claves: Baroclinic waves; semidiurnal; energy flux.
Referencia APA: Bravo, L., Ramos, M., Sobarzo, M., Pizarro, O., & Valle-Levinson, A. (2013). Barotropic and baroclinic semidiurnal tidal currents in two contrasting coastal upwelling zones of Chile. J. Geophys. Res. Oceans, 118(3), 1226-1238
Within-population genetic diversity of climbing plants and trees in a temperate forest in central Chile.
Torres-Díaz, C., Ruiz, E., Salgado-Luarte, C., Molina-Montenegro, M., & Gianoli, E.
The climbing habit is a key innovation in angiosperm evolution: climbing plant taxa have greater species richness than their non-climbing sister groups. It is considered that highly diversified clades should show increased among-population genetic differentiation. Less clear is the expected pattern regarding within-population genetic diversity in speciose lineages. We tested the hypothesis of greater within-population genetic diversity in climbing plants compared to trees in a temperate forest in central Chile. The assumption underlying this hypothesis is that higher among-population differentiation in climbers compared to trees should reflect higher genetic diversity as well. AFLP markers from 167 individual plants from 14 species (seven climbers and seven trees) were used to estimate the following indices of within-population genetic diversity: mean unbiased expected heterozygosity (He), percentage of polymorphic loci (PPL), Shannon information index (I), and the effective number of alleles (Ne). Overall, within-population genetic diversity did not differ between climbing plants and trees. The He for climbing plants was slightly higher than that of trees (0.247 vs. 0.231), and PPL was higher in trees (93.6) than in climbers (81.8), but these differences were not statistically significant. Both I and Ne were very similar for both groups. The expected greater genetic diversity in climbers might have been counterbalanced by tree-related ecological factors that turned to be relevant in the species assemblages studied. Results of this preliminary study should be further confirmed with a broader approach including several forest sites and larger sample sizes.
Año: 2013
Palabras claves: AFLP, climbers, evolution, genetic variability, key innovation.
Referencia APA: Torres-Díaz, C., Ruiz, E., Salgado-Luarte, C., Molina-Montenegro, M., & Gianoli, E. (2013). Within-population genetic diversity of climbing plants and trees in a temperate forest in central Chile. Gayana Bot., 70(1), 36-43
Different photoprotective responses under drought conditions of two predominant Chilean swamp forest species.
Bascuñán-Godoy, L., Alcaíno, C., Carvajal, D., Sanhueza, C., Montecinos, S., & Maldonado, A.
Myrceugenia exsucca (DC.) O.Berg (Myrtaceae) and Luma chequen (Molina) A. Gray (Myrtaceae) are two predominants species from swamp forests of Chile. These species present differential microhabitat distribution across soil moisture and north-south precipitation gradients, with only L. chequen being commonly found in lower moisture sites. It is hypothesized that L. chequen has greater plasticity than M. exsucca in the attributes involved in photoprotection under drought conditions. To test this hypothesis: both species were exposed to short term drought treatment. A group of individuals was maintained irrigated (with of -0.58 and -0.73 MPa for M. exsucca and L. chequen, respectively), while another group was exposed to drought treatment with around -1.4 MPa ( D). High relationship was founded between relative water content (RWC) and water potential () forM. exsucca (r2= 0.74) more than for L. chequen (r2= 0.46), indicating thatM. exsucca experienced larger dehydration during the drought treatment. As functional attributes of photosynthetic apparatus, amount of total chlorophyll and chlorophyll a fluorescence parameter levels were studied in both species. The results show that L. chequen reduced total content of chlorophylls and maximum efficiency of PSII (Fv / Fm) related to decrease of energy capture increasing significantly the thermal dissipation (qN). On the other hand, M. exsucca does not change these parameters, but significantly reduced the level of photochemical processes (qL), indicating an energy imbalance. The results indicate M. exsucca has less plasticity than L. chequen under drought conditions. It is believed that these differences may be crucial in the establishment period and may be influencing the limited distribution ofM. exsucca in sites with lower water availability.
Año: 2013
Palabras claves: Thermal dissipation, water potential, native plants, Myrtaceae family, wetland plants.
Referencia APA: Bascuñán-Godoy, L., Alcaíno, C., Carvajal, D., Sanhueza, C., Montecinos, S., & Maldonado, A. (2013). Different photoprotective responses under drought conditions of two predominant Chilean swamp forest species. Gayana Bot., 70(2), 267-274.
Meteorological drivers of ablation processes on a cold glacier in the semi-arid Andes of Chile.
MacDonell, S., Kinnard, C., Mölg, T., Nicholson, L., & Abermann, J.
Meteorological and surface change measurements collected during a 2.5 yr period are used to calculate surface mass and energy balances at 5324 m a.s.l. on Guanaco Glacier, a cold-based glacier in the semi-arid Andes of Chile. Meteorological conditions are marked by extremely low vapour pressures (annual mean of 1.1 hPa), strong winds (annual mean of 10 m s−1), shortwave radiation receipt persistently close to the theoretical site maximum during cloud-free days (mean annual 295 W m−2; summer hourly maximum 1354 W m−2) and low precipitation rates (mean annual 45 mm w.e.). Snowfall occurs sporadically throughout the year and is related to frontal events in the winter and convective storms during the summer months. Net shortwave radiation provides the greatest source of energy to the glacier surface, and net longwave radiation dominates energy losses. The turbulent latent heat flux is always negative, which means that the surface is always losing mass via sublimation, which is the main form of ablation at the site. Sublimation rates are most strongly correlated with net shortwave radiation, incoming shortwave radiation, albedo and vapour pressure. Low glacier surface temperatures restrict melting for much of the period, however episodic melting occurs during the austral summer, when warm, humid, calm and high pressure conditions restrict sublimation and make more energy available for melting. Low accumulation (131 mm w.e. over the period) and relatively high ablation (1435 mm w.e.) means that mass change over the period was negative (−1304 mm w.e.), which continued the negative trend recorded in the region over the last few decades.
Año: 2013
Palabras claves:
Referencia APA: MacDonell, S., Kinnard, C., Mölg, T., Nicholson, L., & Abermann, J. (2013). Meteorological drivers of ablation processes on a cold glacier in the semi-arid Andes of Chile. The Cryosphere, 7(5), 1513-1526. http://dx.doi.org/10.5194/tc-7-1513-2013
Major hydrological regime change along the semiarid western coast of South America — Response to comments by Maldonado and Moreiras [page number in this issue].
Ortega, C., Vargas, G., & Rutllant, J.
Based on the sedimentology, geomorphology and geochronology of eolian and alluvial deposits at Quebrada Santa Julia (QSJ, 31°50′S) site, in a small coastal watershed in the semiarid central Chile, Ortega et al. (2012) interpreted a regional arid climate setting concomitantly with high local humidity due to reinforced coastal fog development between 13,000 and 8600 cal yr BP. Together with other continental proxies and paleo-SST records off central Chile, Ortega et al. (2012) proposed La Niña-like conditions during the latest Pleistocene‒early Holocene along this semiarid coast. A major hydrologic regime shift shortly after 8600 cal yr BP resulted in higher frequency of torrential rainfall episodes still under an arid climate setting, before the onset of El Niño at ~ 5500 cal yr BP (e.g., Rodbell et al., 1999). This hypothesis differs from that of Maldonado and Moreiras (2013) based on pollen records, who suggest humid conditions associated with precipitation around 13,000 and 10,500 cal yr BP (e.g., Maldonado et al., 2010).
Año: 2013
Palabras claves: Early Holocene; Coastal fog; Rainfall; Hydrologic change; Lifting condensation level; Sea level.
Referencia APA: Ortega, C., Vargas, G., & Rutllant, J. (2013). Major hydrological regime change along the semiarid western coast of South America — Response to comments by Maldonado and Moreiras [page number in this issue]. Quaternary Research, 80(1), 140-142.
Can a breakdown in competition-colonization tradeoffs help explain the success of exotic species in the California flora?
Molina-Montenegro, M., Cleland, E., Watts, S., & Broitman, B.
Determining combinations of functional traits that allow a species to colonize new habitats has been central in the development of invasion ecology. Species able to establish in new communities harbor abilities or traits that allow them to use resources or tolerate stress in ways that native species cannot. Tradeoffs among species functional traits along the competition–colonization (CC) continuum, where competitive ability is a decreasing function of dispersal capacity, may allow invasive species to establish themselves in new habitats. The California flora offers a well-characterized model system to examine whether native and exotic species differ in the distribution of functional traits and to examine whether a breakdown of the CC tradeoff is present. We used a random subset of 1000 plants and examined seed traits and life form characteristics along with their seed size and adult height using the Jepson Manual of the plants of California. To test the hypothesis that active dispersal strategies aid in the success of exotic species, we classified species into four seed types according to the presence/absence of mechanisms associated with efficient dispersal. In addition, for each species we compiled data on seed size and adult plant height. We conducted all comparisons between native and exotic species within the four most speciose families to control for potential taxonomic non-independence. Exotic species had smaller seed size but greater plant height than natives of the same families. On the other hand, exotic species also displayed significantly greater proportions of functional traits that enhanced dispersal ability. Additionally, certain sets of functional traits were significantly associated with exotic species, such as annual life histories with small seeds and high dispersal capacity. In the random subset of the California flora examined, exotics of the most speciose plant families show functional trait combinations that appear to violate the tradeoff structures observed in their California counterparts. Our results suggest that taxonomically controlled comparisons of the CC tradeoff structure between natives and exotic species may shed light of the capacity of those exotic species invasive ability to colonize new habitats.
Año: 2012
Palabras claves:
Referencia APA: Molina-Montenegro, M., Cleland, E., Watts, S., & Broitman, B. (2012). Can a breakdown in competition-colonization tradeoffs help explain the success of exotic species in the California flora?. Oikos, 121(3), 389-395.
Characterization of the interactions between subterranean and superficial fluxes within an Andean catchment as a function of the spatio- temporal variability of climate.
Jourde, H., Blanc, M., Rochette, R., Ruelland, D., Hicks, E., & Oyarzun, R
In the semi-arid region of Norte Chico (Chile), climate variability, mainly controlled by ENSO and LNSO events, generates a high variability of both surface water and groundwater fluxes. Taking the upper Elqui catchment as an example, this study found that, during LNSO events, the abnormally high values of the runoff coefficient may be the consequence of a groundwater contribution to surface water flow. During ENSO events, however, the lower values of the runoff coefficient and the dynamics of the water table level highlight the recharge of the subsurface compartment. For the hydrological years characterized by a high pluviometric index during the 1977–2008 period, three dynamics of interaction between groundwater and surface water are identified : (i) the water table increases before the river discharge, and its logarithmic increase highlights a rapid recharge related to the concomitance of snowmelt and rainfall events ; (ii) the water table increases after the river discharge and its exponential increase shows a progressive intensification of the recharge over time ; and (iii) the water table and the river discharge increase are concomitant. Dynamics (i) and (ii) are observed during the ENSO events, when precipitation occurs over a long time period ; dynamic (iii) is observed during the neutral years, when high intensity precipitations occur over short periods. The analysis of these dynamics and runoff coefficients shows that when the mean annual precipitation is less than 70 mm, the relative equilibrium between runoff and recharge processes is broken, which may generate a high hydrological deficit; this threshold could thus be used as a warning for drought. Finally, the spatial variability of runoff coefficients shows a larger contribution of the subsurface compartment in catchment with a larger proportion of granites, suggesting a mountain front recharge from the alterites in the granitic watershed.
Año: 2012
Palabras claves: hydro-climatic variability, water resource, surface, subsurface interactions, snowmelt, Río Elqui, North-Central Chile.
Referencia APA: Jourde, H., Blanc, M., Rochette, R., Ruelland, D., Hicks, E., & Oyarzun, R. (2012). Caractérisation des interactions entre flux souterrains et superficiels dans un bassin andin en fonction de la variabilité spatio-temporelle du climat. La Houille Blanche, (2), 18-25
Activity patterns and predatory behavior of an intertidal nemertean from rocky shores: Prosorhochmus nelsoni (Hoplonemertea) from the Southeast Pacific.
Caplins, S., Penna-Diaz, M., Godoy, E., Valdivia, N., Turbeville, J., & Thiel, M.
Understanding the impact of environmental stressors on predator activity is a prerequisite to understanding the underlying mechanisms shaping community structure. The nemertean Prosorhochmus nelsoni is a common predator in the mid-intertidal zone on rocky shores along the Chilean coast, where it can reach very high abundances (up to 260 ind m−2) in algal turfs, algal crusts, barnacle crusts, and mixed substrata. Tidal and diurnal scans revealed that the activity of P. nelsoni is primarily restricted to night and early-morning low tides and is relatively low when air temperatures are high. On average, larger worms crawled faster than smaller worms, with their maximum velocity being influenced by substratum type. Their estimated rate of predation is 0.092 prey items nemertean−1 day−1, just below the laboratory rate of ~0.2 amphipods nemertean−1 day−1 previously estimated for this species. P. nelsoni consumes a diverse spectrum of prey items (i.e., amphipods, isopods, decapods, barnacles, and dipterans) and is possibly exerting a significant influence on its prey populations. We suggest that the opportunistic predatory behavior of this intertidal predator is caused by the trade-off between immediate persistence (e.g., avoidance of desiccation) and long-term survival through successful foraging.
Año: 2012
Palabras claves:
Referencia APA: Caplins, S., Penna-Diaz, M., Godoy, E., Valdivia, N., Turbeville, J., & Thiel, M. (2012). Activity patterns and predatory behavior of an intertidal nemertean from rocky shores: Prosorhochmus nelsoni (Hoplonemertea) from the Southeast Pacific. Marine Biology, 159(6), 1363-1374.
Higher plasticity in ecophysiological traits enhances the performance and invasion success of Taraxacum officinale (dandelion) in alpine environments
Molina-Montenegro, M., Peñuelas, J., Munné-Bosch, S., & Sardans, J.
Phenotypic plasticity has long been suggested to facilitate biological invasions in changing environments, allowing a species to maintain a good ecophysiological performance. High-mountain habitats have been particularly useful for evaluation of the relative importance of environmental conditions in the colonization and invasion process, because they have heterogeneous and stressful climatic conditions, inducing photoinhibition. Light intensity is one of the most changing conditions along altitudinal gradients, showing more variability in higher altitudes. In this study, we analyzed the plasticity in photoprotective strategies and performance of the invasive Taraxacum officinale. Additionally, we tested whether higher plasticity enhances competitive ability in an alpine environment We conducted an experiment to evaluate plasticity with a second generation (F2) of T. officinale individuals from 1,600 to 3,600 m, in a greenhouse with variation in light intensity. Treatments consisted of transferring 120 individuals from each altitude to two conditions of light intensity. We then recorded concentrations of photoprotection pigment, de-epoxidation state of the xanthophyll cycle, foliar angles, photochemical efficiency by fluorescence of photosystem II, total dry biomass and flower production. Additionally, we compared plasticity in both photoprotective and performance traits between T. officinale and the co-occurring native species Hypochaeris thrincioides. Finally, we performed a manipulative experiment under two light regimes in order to assess the competitive outcome between the invasive T. officinale and the native H. thrincioides. Individuals from higher altitude showed significantly greater plasticity than individuals from lower altitude. Similarly, individuals under high light intensity showed higher levels of photoprotective pigments, biomass and flower production. On the other hand, the invasive plant species showed significantly greater plasticity than the co-occurring native species, and a strong negative impact on the biomass of the native plant. Phenotypic plasticity seems to be a successful strategy in T. officinale to compete with native species and may be positively associated with the success of invasions, being greater in individuals from more heterogeneous and stressful environments.
Año: 2012
Palabras claves: Altitudinal gradientCompetitionFluorescenceLight intensityPhotoprotective pigmentsXanthophyll cycle
Referencia APA: Molina-Montenegro, M., Peñuelas, J., Munné-Bosch, S., & Sardans, J. (2012). Higher plasticity in ecophysiological traits enhances the performance and invasion success of Taraxacum officinale (dandelion) in alpine environments. Biol Invasions, 14(1), 21-33.
Modelling the Water Sorption Isotherms of Quinoa Seeds (Chenopodium quinoa Willd.) and Determination of Sorption Heats.
Miranda, M., Vega-Gálvez, A., Sanders, M., López, J., Lemus-Mondaca, R., Martínez, E., & Di Scala, K.
Adsorption and desorption isotherms of quinoa seeds (Chenopodium quinoa Willd.) were measured using the static gravimetric method at three temperatures (20, 40 and 60 °C). Water activity ranged from 0.118 to 0.937. The moisture sorption behaviour of quinoa was temperature dependent, as indicated by a decrease in equilibrium moisture content, at all levels of aw, with increasing temperature. Eight mathematical equations available in the literature were used to model the experimental data, namely, GAB, BET, Caurie, Henderson, Oswin, Halsey, Smith and Iglesias–Chirife. All the equations showed generally a good fit; however, the Iglesias–Chirife and Oswin equations were considered the best to predict the experimental data for both isotherms. Effect of temperature on model parameters was analysed and studied through an Arrhenius-type equation. The net isosteric heats of desorption and adsorption were determined by applying the Clausius–Clapeyron equation resulting in 69.24 kJ mol−1 for desorption and 61.26 kJ mol−1 for adsorption. The experimental heat data were satisfactorily modelled by Tsami’s equation.
Año: 2012
Palabras claves: Quinoa, Sorption isotherms, Isosteric sorption heat, Mathematical modelling.
Referencia APA: Miranda, M., Vega-Gálvez, A., Sanders, M., López, J., Lemus-Mondaca, R., Martínez, E., & Di Scala, K. (2012). Modelling the Water Sorption Isotherms of Quinoa Seeds (Chenopodium quinoa Willd.) and Determination of Sorption Heats. Food Bioprocess Technol, 5(5), 1686-1693.