CEAZA
Importance of geochemical factors in determining distribution patterns of aquatic invertebrates in mountain streams south of the Atacama Desert, Chile.
Alvial, I., Orth, K., Durán, B., Álvarez, E., & Squeo, F.
The ecology of macroinvertebrate communities in arid regions is still poorly understood. Here we examined how the community structure varied at spatial and temporal scales in streams and tributaries of the Huasco River in semi-arid region of Northern Chile. We expected that macroinvertebrate distribution may be responding to natural processes of mineralization described for Chilean semiarid basins. The relationships among biotic and abiotic variables were assessed through multivariate techniques (principal component analysis, non-metric multidimensional scaling, canonical correspondence analysis), and a two-way analysis of similarity was used to evaluate differences between basins and years (2007, 2008, and 2009). Significant differences in community structure and physical–chemical variables between basins (Del Carmen and Del Tránsito) were found, but not between years. Altitude, Mn, Al, Ca, Na, HCO3, and dissolved oxygen were the variables that best accounted for the communities distribution. In particular, high metals concentration in El Transito basin should determine low density and diversity of macroinvertebrates. Chironomidae, Ephydridae, and Glossiphoniidae were associated to waters with high metals content and acidic pH, whereas Baetidae, Hydroptilidae, and Blephariceridae were associated to sites with more favorable physical–chemical conditions. These results contribute to understand the ecological patterns of macroinvertebrates in arid regions and should lead to conservation and monitoring plans for this remote place.
Año: 2013
Palabras claves: Huasco basin, Desert climate, Macroinvertebrates, Biomonitoring, Habitat variables, Handling editor: Koen Martens
Referencia APA: Alvial, I., Orth, K., Durán, B., Álvarez, E., & Squeo, F. (2013). Importance of geochemical factors in determining distribution patterns of aquatic invertebrates in mountain streams south of the Atacama Desert, Chile. Hydrobiologia, 709(1), 11-25.
Estimating Spatial Distribution of Air Temperature from Meteorological Stations Using Atmospheric Model.
Montecinos, S., Bascuñán-Godoy, L., Salinas, P., Astudillo, O., & Lopez, D.
Planning agricultural procedures needs to take into account meteorological conditions. However, because of high associated costs, the density of meteorological stations is often not enough to cover all the cultivated or potentially cultivated areas. In this article we present a methodology to estimate seasonal maximum and minimum mean temperature in cultivated area using data registered in a sole or a few meteorological stations. The procedure is based on mesoscale modeling, which allows meteorological variables to be spatially distributed considering synoptic data and local characteristics.
Simulated daily cycle of temperature was compared with data registered at six meteorological stations located in the cultivated floor of the semiarid Limari Valley (Chile, 31°S). Although in some cases the simulated temperature differs in about 2°C with the observed one, a good fit between model results and experimental data was observed. Using the simulated seasonal minimum and maximum mean temperature fields, maps of temperature differences with respect to a reference station were drawn. In order to observe the influence of the orography on the lapse rate around a station, the methodology was applied for two reference stations located in places with different orographic characteristics. Results for winter and summer seasons are shown.
These generated maps can be used by farmers and agricultural planners to obtain information of seasonal minimum and maximum mean temperature from a station in any site of the cultivated area. This technique is a good alternative to obtain meteorological information at low costs, contributing to territorial planning for climate resilient agriculture sustainability.
Año: 2013
Palabras claves:
Referencia APA: Montecinos, S., Bascuñán-Godoy, L., Salinas, P., Astudillo, O., & Lopez, D. (2013). Estimating Spatial Distribution of Air Temperature from Meteorological Stations Using Atmospheric Model. Journal Of Agricultural Science, 5(2).
Positive interactions between the lichen Usnea antarctica (Parmeliaceae) and the native flora in Maritime Antarctica.
Molina-Montenegro, M., Ricote-Martínez, N., Muñoz-Ramírez, C., Gómez-González, S., Torres-Díaz, C., Salgado-Luarte, C., & Gianoli, E.
Eight out of 13 species were positively associated with cushions of the widespread lichen U. antarctica, while only one species (U. aurantiaco-atra) showed a negative association with U. antarctica. Survival of Deschampsia was enhanced when growing associated with U. antarctica cushions. Our results indicate that cushions ameliorated the extreme conditions of Antarctic islands through increased temperature and soil moisture, decreased radiation and evaporative water loss and increased nutrient availability.
Año: 2013
Palabras claves: Antarctica; Deschampsia antarctica ; Facilitation; Global warming; Lichens; Mosses; Nurse effect.
Referencia APA: Molina-Montenegro, M., Ricote-Martínez, N., Muñoz-Ramírez, C., Gómez-González, S., Torres-Díaz, C., Salgado-Luarte, C., & Gianoli, E. (2013). Positive interactions between the lichen Usnea antarctica (Parmeliaceae) and the native flora in Maritime Antarctica. J Veg Sci, 24(3), 463-472. http://dx.doi.org/10.1111/j.1654-1103.2012.01480.x
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
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.
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.