CEAZA
Seabirds modify El Niño effects on tree growth in a southern Pacific island.
Molina-Montenegro, M., Torres-Díaz, C., Gallardo-Cerda, J., Leppe, M., & Gianoli, E.
Oceanic island ecosystems are particularly sensitive to El Niño effects due to their dependence on energy and nutrient inputs from marine systems. Seabirds play a key role in transporting resources of marine origin to insular ecosystems. We report tree-growth patterns showing how the effects of El Niño rainy events on tree species in a southern Pacific island depend on the presence of local seabird colonies. We performed manipulative experiments in order to assess the mechanisms underlying these patterns. Tree ring data showed that, in normal years, the growth of all tree species (Aextoxicon punctatum, Cryptocarya alba, and Pinus radiata) was significantly lower in seabird sites compared to adjacent patches without seabirds (control sites). In contrast, in El Niño years, trees formerly hosting seabird colonies grew more than those in control sites. Experiments showed that (1) pine plants on soil from seabird sites grew more than those on soil from control sites, (2) pine individuals with seabird feces on their leaves grew less than those sprayed with an aqueous solution, and (3) soil moisture had little effect on plant growth. The stress produced by massive cormorant nesting on trees, which impairs tree growth and physiological performance, is relieved during El Niño events because of seabird migration due to decreased prey availability and pouring rains that flood nests. Soils enriched by the seabird guano, together with the increased water availability associated with El Niño, foster the growth of trees from seabird sites. We suggest that El Niño may be a key determinant of tree performance in forest communities from island and coastal ecosystems of the Pacific Ocean.
Año: 2013
Palabras claves: Aextoxicon punctatum; colonial seabirds; Cryptocarya alba; ecophysiology; El Niño Southern Oscillation, ENSO; global change; island system interactions; Neotropic Cormorant, Phalacrocorax brasilianus; Pinus radiata; Quiriquina Island, Chilean coast; tree rings.
Referencia APA: Molina-Montenegro, M., Torres-Díaz, C., Gallardo-Cerda, J., Leppe, M., & Gianoli, E. (2013). Seabirds modify El Niño effects on tree growth in a southern Pacific island. Ecology, 94(11), 2415-2425.
Variabilidad ambiental y recursos pesqueros en el Pacifico suroriental: estado de la investigacion y desafios para el manejo pesquero.
Parada, C., Yannicelli, B., Hormazabal, S., Vasquez, S., Porobic, J., & Ernst, B. et al.
Las fluctuaciones en abundancia, biomasa, estructura de edad y patrones de distribución de los recursos pesqueros responden, entre otros, a la variabilidad ambiental. Estas respuestas son consecuencia tanto de efectos climáticos directos sobre los recursos como indirectos actuando sobre niveles tróficos relacionados. En este estudio se revisa: i) el estado del conocimiento de los mecanismos físicos asociados a la variabilidad océano-atmósfera y las escalas de variabilidad espaciales y temporales del ambiente y la relación con recursos marinos, basados en datos observacionales y modelos hidrodinámicos, ii) la relación ambiente-recurso para pesquerías pelágicas, demersales y bentónicas, y el uso de modelos biofísicos para entender estas relaciones, iii) manejo actual de recursos pelágicos, demersales y bentónicos y los alcances en relación al uso de variables ambientales, y iv) se discuten los desafíos hacia la asesoría en relación a las estrategias para mejorar la comprensión de la relación ambiente-recurso, así como, las estrategias para incorporar la modelación biofísica y variables ambientales en modelos operacionales para la asesoría hacia el manejo.
Año: 2013
Palabras claves: Variabilidad ambiental, sistemas de surgencia, recursos pesqueros, modelación biofísica, dinámica poblacional, modelos operacionales para el manejo pesquero, Pacífico suroriental, Chile.
Referencia APA: Parada, C., Yannicelli, B., Hormazabal, S., Vasquez, S., Porobic, J., & Ernst, B. et al. (2013). Variabilidad ambiental y recursos pesqueros en el Pacifico suroriental: estado de la investigacion y desafios para el manejo pesquero. Latin American Journal Of Aquatic Research, 41(1), 1-28.
Differential effects of grazer species on periphyton of a temperate rocky shore.
Aguilera, M., Navarrete, S., & Broitman, B.
Species-specific traits are relevant to understand variation in the effect of grazers on primary producers and are critical in determining their functional roles as controllers of productivity in marine ecosystems. In intertidal habitats, periphyton, composed of bacteria, cyanophytes, microalgae and early stages of macroalgae, constitutes the main food for many benthic grazers. Using field experiments, we examined the overall effect of grazers and the importance of direct and indirect effects of different grazer species on periphyton composition, richness, diversity and productivity. We manipulated the main grazer species present along Chilean rocky shores, enclosing adult individuals of the keyhole limpet Fissurella crassa, the chiton Chiton granosus, the scurrinid limpet Scurria araucana and the pulmonate limpet Siphonaria lessoni. These organisms overlap broadly in diet but exhibit differences in foraging behavior. Differences in the individual effects of grazer species on periphyton productivity, as well as on richness and diversity characterized the assemblage. C. granosus grazing led to lower periphyton productivity, richness and diversity compared with all other grazers, who had positive effects for all variables. Richness and diversity of the major periphyton groups were maximal at intermediate levels of total grazing pressure, highlighting the importance of ecological interactions within the periphyton assemblage. Our results demonstrate the complexity of functional roles and relationships of grazers involved in the control of composition and production of the periphyton assemblage. Given the importance of direct and indirect effects of grazers, understanding species interactions within the microbenthic community can shed light on the mechanisms through which herbivores modify community structure and productivity.
Año: 2013
Palabras claves: Grazer assemblage, Periphyton, Productivity, Diversity, Foraging behavior.
Referencia APA: Aguilera, M., Navarrete, S., & Broitman, B. (2013). Differential effects of grazer species on periphyton of a temperate rocky shore. Marine Ecology Progress Series, 484, 63-78.
Environmental and climatic changes in Central Chilean Patagonia since the Late Glacial (Mallín El Embudo, 44° S).
de Porras, M., Maldonado, A., Quintana, F., Martel-Cea, A., Reyes, O., & Méndez, C.
Multi-millennial environmental and climatic changes in central Chilean Patagonia (44–49° S) during the Last Glacial–Interglacial cycle have been of particular interest as changes in the position and strength of the southern westerlies are the major forcing factor conditioning the environmental dynamics. Recent attempts to reconstruct regional environmental and climatic signals from central Chilean Patagonia reveal some discrepancies and unclear issues among the records. This paper presents the 13 ka pollen and charcoal records from Mallín El Embudo (44° 40' S, 71° 42' W) located in the deciduous Nothofagus forest in the middle Río Cisnes valley. The paper aims to (1) establish the timing and magnitude of local vegetation changes and fire activity since the Late Glacial and (2) integrate these results at the regional scale in order to discuss the discrepancies and depict the environmental and climatic dynamics in central Chilean Patagonia since the Late Glacial. Open landscapes dominated by grasses associated with scattered Nothofagus forest patches dominated the middle Río Cisnes valley between 13 and 11.2 ka suggesting low effective moisture but also indicating that landscape configuration after glacial retreat was still ongoing. At 11.2 ka, the sudden development of an open and quite dynamic Nothofagus forest probably associated with the synchronous high fire activity occurred, suggesting a rise in effective moisture associated with dry summers. Since 9.5 ka, the record reflects the presence of a closed Nothofagus forest related to higher effective moisture conditions than before combined with moderate dry summers that may have triggered a high frequency of low-magnitude crown fires that did not severely affect the forest. The forest experienced a slight canopy opening after 5.7 ka, probably due to slightly drier conditions than before followed by a sudden change to open forest conditions around 4.2 ka associated with fire and volcanic disturbances. Around 2 ka, the recovery of a closed Nothofagus forest related to slightly wetter conditions (similar to present) occurred and persisted under highly variable climatic conditions up to 0.1 ka when massive forest burning and logging due to European settlements occurred. Central Chilean Patagonian climatic and environmental changes at millennial–centennial timescales since the Late Glacial were driven by changes in the southern westerlies latitudinal position and/or intensity, but during the late Holocene fire, volcanism and humans arose as forces contributing to environmental dynamics.
Año: 2013
Palabras claves:
Referencia APA: de Porras, M., Maldonado, A., Quintana, F., Martel-Cea, A., Reyes, O., & Méndez, C. (2013). Environmental and climatic changes in Central Chilean Patagonia since the Late Glacial (Mallín El Embudo, 44° S). Clim. Past Discuss., 9(5), 5747-5784.
Hydrochemical and isotopic patterns in a calc-alkaline Cu- and Au-rich arid Andean basin: The Elqui River watershed, North Central Chile.
Oyarzún, J., Carvajal, M., Maturana, H., Núñez, J., Kretschmer, N., & Amezaga, Röttingd, T.S., Strauche, G., Thynef, G., Oyarzún,R.
The geochemistry of surface water and groundwater from the Elqui River basin, North-Central Chile, was studied in spring 2007 and fall 2008 to obtain a general understanding of the factors and mechanisms controlling the water chemistry of steep rivers located in mineral-rich, arid to semi arid zones. Besides its uniform intermediate igneous lithology, this basin is known for acid drainage and high As contents in the El Indio Au–Cu–As district, in its Andean head. Abundant tailings deposits are present in the middle part of the basin, where agricultural activities are important. According to the results, the chemical and isotopic composition of the Elqui basin surface water and groundwater is related to uniform calc-alkaline lithology and the major polluting system of the chemically reactive, but closed El Indio mining district. The resulting compositional imprints in surface and ground-water are, (a) high SO4 levels, reaching about 1000 mg/L in the Toro River water, directly draining the mining area; (b) a major depletion of Fe and pollutant metals in surface water after the confluence of the Toro and La Laguna rivers; (c) similar chemical composition of surface and ground-waters that differ in H and O isotopic composition, reflecting the effect of differential evaporation processes downstream of the Puclaro dam; and (d) seasonal variations of Fe, Mn, Cu and Zn in surface water. In contrast, the groundwater chemistry exhibits moderate seasonal changes, mainly in View the MathML source content. In spite of the acid drainage pollution, water quality is adequate for human consumption and irrigation. This is a consequence of both the dominant calc-alkaline lithology and the existing arid climate, resulting in neutral to moderately alkaline pH values that are responsible for the precipitation of metal hydroxides and As sorption by Fe(OH)3.
Año: 2013
Palabras claves:
Referencia APA: Oyarzún, J., Carvajal, M., Maturana, H., Núñez, J., Kretschmer, N., & Amezaga, Röttingd, T.S., Strauche, G., Thynef, G., Oyarzún, R. (2013). Hydrochemical and isotopic patterns in a calc-alkaline Cu- and Au-rich arid Andean basin: The Elqui River watershed, North Central Chile. Applied Geochemistry, 33, 50-63.
Metabolic responses of the squat lobster (Pleuroncodes monodon) larvae to low oxygen concentration.
Yannicelli, B., Paschke, K., González, R., & Castro, L.
Squat lobster populations found in the Humboldt Current System over the continental shelf from ~28 to 37°S release pelagic larvae in sub-surface cold (~11 °C) hypoxic waters. Larvae subsequently spread throughout the water column encountering both normoxic and hypoxic conditions. We analyzed some short- and long-term responses of Pleuroncodes monodon larval metabolism to hypoxia at 11 °C. Routine and postprandial aerobic respiration rates were lower in hypoxia than in normoxia for all zoeal stages. Zoea V oxyconformed, while megalopae oxyregulated down to very low oxygen concentrations. Throughout zoea I development, the rate of nitrogen (protein) accumulation in zoea I was lower, and C:N ratios were higher under hypoxic conditions than in normoxia. Citrate synthase (CS) and malate dehydrogenase (MDH) apparent specific activities (as indicators of aerobic and metabolic potentials, respectively) decreased and remained at the same level, respectively, throughout zoea I reared under hypoxic conditions. Anaerobic to aerobic potential (lactate dehydrogenase (LDH)/CS) was higher in organisms reared under hypoxia, and MDH/LDH potential ratios were characteristic of organisms tolerant to hypoxia. In spite of P. monodon zoea endurance and metabolic adaptations to decreasing oxygen tensions, intense hypoxia as such of their release site would affect their overall condition especially toward the end of the molt cycle. Our results indicate the importance of considering the interaction between environmental oxygen variability and recruitment success.
Communicated by H.-O. Portner.
Año: 2013
Palabras claves:
Referencia APA: Yannicelli, B., Paschke, K., González, R., & Castro, L. (2013). Metabolic responses of the squat lobster (Pleuroncodes monodon) larvae to low oxygen concentration. Marine Biology, 160(4), 961-976
Spatial niche differentiation and coexistence at the edge: co-occurrence distribution patterns in Scurria limpets.
Aguilera, M., Valdivia, N., & Broitman, B.
Examining the co-occurrence of taxonomically similar species can provide important information about their niches and coexistence. Segregation at smaller scales can be especially relevant for grazers living at the edge of their geographic distribution, because environmental factors can lead to similar distribution. Related grazer species may show dispersive, i.e. uniform, distribution at small scales (few centimetres) to reduce interference among individuals. We examined intra- and interspecific spatial distribution and habitat use in 2 phylogenetically related intertidal limpets, Scurria viridula and S. zebrina, at the polar and equatorial edge of their geographic distribution, respectively, and in S. araucana, a widely distributed species that overlaps the range of the other 2 species across the southeastern Pacific. S. viridula and S. zebrina overlapped in a narrow geographic zone (ca. 250 km) and reached relatively similar densities and sizes. Intraspecific spatial structure estimated through autocorrelation and individual-to-individual distances was random for S. viridula and variable for S. zebrina and S. araucana, depending on the scale considered; S. zebrina was aggregated at the individual-to-individual distances, while S. araucana was mostly random at this scale. Segregated distribution between S. viridula and S. zebrina was observed at the finer scale, whereas the association with S. araucana was random. Abundance of limpets loosely followed major habitats, namely bare rock and the alga Mazzaella laminarioides, which showed patchy distributions. We suggests that similarity in population traits between S. viridula and S. zebrina found in the overlap zone may be compensated by small-scale spatial segregation. Thus, at the edge of their geographic distribution, coexistence between related species may be influenced by spatial niche differentiation driven by habitat suitability or competition.
Año: 2013
Palabras claves: Coexistence, Geographic edge, Grazers, Habitat type, Niche partitioning, Nearest neighbour, Spatial autocorrelation.
Referencia APA: Aguilera, M., Valdivia, N., & Broitman, B. (2013). Spatial niche differentiation and coexistence at the edge: co-occurrence distribution patterns in Scurria limpets. Marine Ecology Progress Series, 483, 185-198.
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.
An Early Holocene task camp (~8.5 ka cal BP) on the coast of the semi-arid north of Chile.
Ballester, B., Jackson, D., Carré, M., Maldonado, A., Méndez, C., & Seguel, R.
According to current thinking, the peopling of South America involved a coastal as well as an inland exploitation. Here the authors describe a camp that may denote a transition between the two. As indicated by bifacial tools, the investigation shows that people began to move inland and hunt mammals around 8500 cal BP, perhaps in association with a change in the climate.
Año: 2012
Palabras claves: Chile, peopling of South America, coastal, inland, shell, midden, bifacies
Referencia APA: Ballester, B., Jackson, D., Carré, M., Maldonado, A., Méndez, C., & Seguel, R. (2012). An Early Holocene task camp (~8.5 ka cal BP) on the coast of the semi-arid north of Chile. Antiquity, 86(331), 88-98.
Lizards on Ice: Evidence for Multiple Refugia in Liolaemus pictus (Liolaemidae) during the Last Glacial Maximum in the Southern Andean Beech Forests.
Vera-Escalona, I., D'Elía, G., Gouin, N., Fontanella, F., Muñoz-Mendoza, C., Sites, J., & Victoriano, P.
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.
Referencia APA: Vera-Escalona, I., D'Elía, G., Gouin, N., Fontanella, F., Muñoz-Mendoza, C., Sites, J., & Victoriano, P. (2012). Lizards on Ice: Evidence for Multiple Refugia in Liolaemus pictus (Liolaemidae) during the Last Glacial Maximum in the Southern Andean Beech Forests. Plos ONE, 7(11), e48358.