CEAZA
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.
Condiciones paleovegetacionales y asentamientos humanos durante el formativo temprano: análisis de polen del sitio Tulán-85 (1.530/1.260-460/420 años cal. a.c.), cuenca del Salar de Atacama.
González-Silvestre, L., Maldonado, A., Núñez, L., Cartajena, I., Carrasco, C., & de Souza, P.
Se presenta el análisis polínico obtenido de una columna estratigráfica que cubre toda la secuencia ocupacional del asentamiento formativo temprano Tulán-85 localizado al sureste del salar de Atacama fechado entre los 1.530-1.260 a 460-420 cal. a.C. Se concluye que es posible diferenciar mediante el polen actual tres pisos altitudinales de vegetación, al tanto que la comparación de las muestras fósiles con aquellas actuales sugieren condiciones de mayor humedad en la base de la secuencia, al comienzo de la fase Tilocalar (1.530-1.260 cal. a.C.). En los niveles medios comienzan los eventos áridos, identificándose al final de la columna los mayores indicadores de aridez. Los antecedentes paleoclimáticos de la alta puna señalan que las ocupaciones pastoralistas de la fase Tilocalar son sincrónicas con el establecimiento de condiciones más húmedas, lo que es concordante con los resultados del análisis polínico. Estas habrían repercutido favorablemente en las ocupaciones pastoralistas en los pisos inferiores. Es importante destacar la identificación de eventos de aridez hacia el final de la ocupación, los que no habían sido descritos con anterioridad para el área de estudio.
Año: 2013
Palabras claves: Formativo Temprano, polen fósil, condiciones húmedas, eventos áridos, salar de Atacama.
Referencia APA: González-Silvestre, L., Maldonado, A., Núñez, L., Cartajena, I., Carrasco, C., & de Souza, P. (2013). Condiciones paleovegetacionales y asentamientos humanos durante el formativo temprano: análisis de polen del sitio Tulán-85 (1.530/1.260-460/420 años cal. a.c.), cuenca del Salar de Atacama. Chungará (Arica), 45(3), 387-410.
Parameterisation of incoming longwave radiation over glacier surfaces in the semiarid Andes of Chile.
MacDonell, S., Nicholson, L., & Kinnard, C.
A good understanding of radiation fluxes is important for calculating energy, and hence, mass exchange at glacier surfaces. This study evaluates incoming longwave radiation measured at two nearby glacier stations in the high Andes of the Norte Chico region of Chile. These data are the first published records of atmospheric longwave radiation measurements in this region. Nine previously published optimised parameterisations for clear sky emissivity all produced results with a root mean square error (RMSE) ~20 W m−2 and bias within ±5 W m−2, which is inline with findings from other regions. Six optimised parameterisations for incoming longwave in all sky conditions were trialled for application to this site, five of which performed comparably well with RMSE on daytime data <18 W m−2 and bias within ±6 W m−2 when applied to the optimisation site and RMSE <20 W m−2 and bias within ±10 W m−2 when applied to the validation site. The parameterisation proposed by Mölg et al. (J Glaciol 55:292-302, 2009) was selected for use in this region. Incorporating the proposed elevation modification into the equation reduced the bias in the modelled incoming longwave radiation for the validation site. It was found that applying the parameterisation optimised in the original work at Kilimanjaro produced good results at both the primary and validation site in this study, suggesting that this formulation may be robust for different high mountain regions.
Año: 2013
Palabras claves:
Referencia APA: MacDonell, S., Nicholson, L., & Kinnard, C. (2013). Parameterisation of incoming longwave radiation over glacier surfaces in the semiarid Andes of Chile. Theoretical And Applied Climatology, 111(3-4), 513-528.
Ecophysiological constraints on the larvae of Pleuroncodes monodon and the implications for its reproductive strategy in poorly oxygenated waters of the Chile-Peru undercurrent.
Yannicelli, B. & Castro, L.
Pleuroncodes monodon is a conspicuous component of the Humboldt Current ecosystem. Benthic adults south of ∼22°S are associated with low temperature (T) ∼11°C and low dissolved oxygen (DO) (<0.5 mL L−1) waters during the hatching period. Because P. mondon inhabits an oxygen minimum zone and larval release is assumed to match most favorable environmental conditions, larval performance under cold hypoxic conditions and its implications have not yet been assessed experimentally. We quantitatively assessed the effect of DO and T within environmental ranges, and initial starvation on survival, developmental time, and growth of P. monodon zoeae. Molting success from zoea I to zoea II was significantly and positively dependent on DO rearing levels. Age at molting was a negative power function of oxygen concentration. Initial exposure to low DO increased larval mortality by 3% per day of exposure. After ∼4 and ∼1.5 days of starvation after birth under normoxia and hypoxia, respectively, 50% of larvae failed to molt to zoea II. Rearing in 1 mL L−1 DO produced 50% lighter larvae after molting into zoea II. Mortality of larvae reared at 11°C was 40% higher than that at 15 and 20°C. Functions for development time and growth negative/positive dependence on temperature were also fitted. Pleuroncodes monodon zoea I are highly tolerant of low oxygen when compared with other crustacean. Nevertheless, DO and T conditions during hatching season are suboptimal for development. Early larval survival as an ultimate cause of reproductive/environmental coupling in this case should be critically revised.
Año: 2013
Palabras claves: Developmental time, growth, hypoxia, Pleuroncodes monodon, point-of-no-return, survival, temperature.
Referencia APA: Yannicelli, B. & Castro, L. (2013). Ecophysiological constraints on the larvae of Pleuroncodes monodon and the implications for its reproductive strategy in poorly oxygenated waters of the Chile-Peru undercurrent. Journal Of Plankton Research, 35(3), 566-581.
Linking human activity and ecosystem condition to inform marine ecosystem based management.
Menzel, S., Kappel, C., Broitman, B., Micheli, F., & Rosenberg, A.
There is growing consensus that integrated marine management is needed. However, implementation of ecosystem-based management (EBM) faces major operational challenges, including accurately delineating the links between ecosystem components and benefits to humans, and quantifying trade-offs associated with different management decisions.
It is suggested using human activity level as an indicator of the benefit provided by marine ecosystems at a certain location in comparison with other locations and establishing links between human activity levels and ecological conditions.
This approach allows for the determination of what ecological conditions may provide the greatest human benefits and thus may be targets for management action.
This approach is used to investigate the link between scuba diving in the Monterey Bay area, California, USA, and different ecological characteristics of kelp forests. Diving intensity levels correlate with kelp persistence, suggesting that kelp persistence may be used as an indicator of benefits from diving and for evaluating the impact of potentially competing activities through their effects on kelp.
Overall, an operational definition of marine ecosystem services is provided and it is suggested that this method could be extended to a suite of different activities and systems and thus may become useful in considering trade-offs among different activities that depend upon the same ecosystem.
Año: 2013
Palabras claves: Ecosystem services; natural resource management; ecological indicators; Monterey Bay; California; kelp forest ecosystem; scuba diving; ecological production function; human benefits from ecosystems.
Referencia APA: Menzel, S., Kappel, C., Broitman, B., Micheli, F., & Rosenberg, A. (2013). Linking human activity and ecosystem condition to inform marine ecosystem based management. Aquatic Conserv: Mar. Freshw. Ecosyst., 23(4), 506-514.
The response of leaf respiration to water stress in Nothofagus species.
Sanhueza, C., Bascunan-Godoy, L., Corcuera, L., & Turnbull, M.
Nothofagus solandri is regarded as more tolerant to drought than Nothofagus menziesii in the field. However, the physiology of responses to water limitation in these species is not well understood. In this study, the thermal sensitivity of leaf respiration and its underlying metabolism in response to drought were investigated in mature trees and saplings. Respiration (R d) and photosynthesis (A max) were measured during drying and re-wetting cycles. In addition, respiratory pathway changes were evaluated by oxygen isotope fractionation and protein analyses. Under drought treatment in the glasshouse, both species showed similar photosynthetic performance, but under mild water stress N. solandri was able to increase A max. Under moderate water deficit (around −2 MPa), N. solandri increased respiration at a base temperature of 10°C (R 10) but then decreased it to initial values after re-watering. In N. menziesii, R 10 did not respond significantly to water-stress treatment. The temperature sensitivity of R d (Q 10 and E o) was unchanged for both species during the gradual deficit water treatment in the glasshouse. Although respiratory electron flow was mainly via the cytochrome pathway under all conditions, an increase in alternative oxidase/cytochrome oxidase protein content suggests that the alternative pathway is involved in modulating respiratory metabolism during the recovery after drought.
Año: 2013
Palabras claves: Alternative oxidase, cytochrome oxidase, drought, metabolism, New Zealand, trees.
Referencia APA: Sanhueza, C., Bascunan-Godoy, L., Corcuera, L., & Turnbull, M. (2013). The response of leaf respiration to water stress in Nothofagus species. New Zealand Journal Of Botany, 51(2), 88-103.
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.
Functional identity and functional structure change through succession in a rocky intertidal marine herbivore assemblage.
Aguilera, M. & Navarrete, S.
Despite the great interest in characterizing the functional structure and resilience of functional groups in natural communities, few studies have examined in which way the roles and relationships of coexisting species change during community succession, a fundamental and natural process that follows the release of new resources in terrestrial and aquatic ecosystems. Variation in algal traits that characterize different phases and stages of community succession on rocky shores are likely to influence the magnitude, direction of effects, and the level of redundancy and complementarity in the diverse assemblage of herbivores. Two separate field experiments were conducted to quantify per capita and population effects and the functional relationship (i.e., redundancy or complementarity) of four herbivore species found in central Chile during early and late algal succession. The first experiment examined grazer effects on the colonization and establishment of early-succession algal species. The second experiment examined effects on the late-successional, dominant corticated alga Mazzaella laminarioides. Complementary laboratory experiments with all species and under natural environmental conditions allowed us to further characterize the collective effects of these species. We found that, during early community succession, all herbivore species had similar effects on the ephemeral algae, ulvoids, but only during the phase of colonization. Once these algae were established, only a subset of the species was able to control their abundance. During late succession, only the keyhole limpet Fissurella crassa could control corticated Mazzaella. The functional relationships among these species changed dramatically from redundant effects on ephemeral algae during early colonization, to a more complementary role on established early-successional algae, to a dominant (i.e., keystone) effect on late succession. This study highlights that functional relationship within consumer assemblages can vary at different phases and times of community succession. Differentiation in herbivore roles emphasizes the need to evaluate consumer's impacts through different times of community succession, and through experimental manipulations to make even broad predictions about the resilience or vulnerability of diverse intertidal assemblages to human disturbances.
Año: 2012
Palabras claves: Chile; ephemeral algae; functional redundancy; functional roles; grazing; herbivores; human impact; interaction strength; keystone species; rocky shore
Referencia APA: Aguilera, M. & Navarrete, S. (2012). Functional identity and functional structure change through succession in a rocky intertidal marine herbivore assemblage. Ecology, 93(1), 75-89. http://dx.doi.org/10.1890/11-0434.1
Recent melt rates of Canadian arctic ice caps are the highest in four millennia. Global And Planetary Change
Fisher, D., Zheng, J., Burgess, D., Zdanowicz, C., Kinnard, C., Sharp, M., & Bourgeois, J.
There has been a rapid acceleration in ice-cap melt rates over the last few decades across the entire Canadian Arctic. Present melt rates exceed the past rates for many millennia. New shallow cores at old sites bring their melt series up-to-date. The melt-percentage series from the Devon Island and Agassiz (Ellesmere Island) ice caps are well correlated with the Devon net mass balance and show a large increase in melt since the middle 1990s. Arctic ice core melt series (latitude range of 67 to 81 N) show the last quarter century has had the highest melt in two millennia and The Holocene-long Agassiz melt record shows that the last 25 years has the highest melt in 4200 years. The Agassiz melt rates since the middle 1990s resemble those of the early Holocene thermal maximum over 9000 years ago.
Año: 2012
Palabras claves: Ice core; Melt layers; Holocene; Warming; Ice caps
Referencia APA: Fisher, D., Zheng, J., Burgess, D., Zdanowicz, C., Kinnard, C., Sharp, M., & Bourgeois, J. (2012). Recent melt rates of Canadian arctic ice caps are the highest in four millennia. Global And Planetary Change, 84-85, 3-7.