CEAZA
Hormonal and physiological changes driven by fungal endophytes increase Antarctic plant performance under UV-B radiation
Ramos, P., Rivas, N., Pollmann, S., Casati, P. and Molina-Montenegro, M.
Antarctic environments are amongst the most stressful habitats for life on Earth, with high intensities of solar UV-B radiation reaching the land surface. In this study, we evaluated how the photochemical efficiency, cell damage and reproductive biomass of Antarctic pearlwort (Colobanthus quitensis) were affected by different intensities of UV-B radiation in the absence and presence of fungal endophytes. In addition, we evaluated the hormonal content of plants at different UV-B radiation intensities and how hormonal content was affected by endophytes. Overall, plants exposed to UV-B radiation showed higher numbers of flowers, higher total biomass and lower lipid peroxidation in the presence of endophytes compared with plants without endophytes. Photochemical efficiency was unaffected. Fungal endophytes affected the content of salicylic acid, jasmonate, indole-3-acetate and abscisic acid in shoot tissue of plants exposed to UV-B radiation. These results suggest that endophytes could modulate the hormonal content of C. quitensis to improve its ecophysiological performance under high UV-B radiation.
Año: 2018
Palabras claves: Antarctica, Climate change, Colobanthus quitensis, Ecophysiological performance, Fungal endophytes
Referencia APA: Ramos, P., Rivas, N., Pollmann, S., Casati, P. and Molina-Montenegro, M. (2018). Hormonal and physiological changes driven by fungal endophytes increase Antarctic plant performance under UV-B radiation. Fungal Ecology, 34, pp.76-82.
Scales of predator detection behavior and escape in Fissurella limbata: A field and laboratory assessment
Manzur, T., Gonzalez-Mendez, A. and Broitman, B.
The consumptive effects of predators are widely acknowledged, but predation can also impact prey populations through non‐consumptive effects (NCEs) such as costly antipredator behavioral responses. The magnitude of antipredator behavioral responses by prey is determined by an assessment of risk using sensory cues, which in turn is modulated by the environmental context. We studied the detection behavior and escape response of the keyhole limpet Fissurella limbata from the predatory sea star Heliaster helianthus. Through laboratory and field experimental trials, we quantified the distance and time of predator detection behavior by the prey, and measured their active escape responses when elicited. We found that predator detection by the limpet was chiefly mediated by distance, with experimental individuals capable of detecting predator presence effectively up to distances of at least 50 cm in the field and 70 cm under laboratory conditions. Our results indicate that this prey species is able to evaluate the proximity of its predator and use it as an indication of predation risk; therefore, predator–prey distance appears to be a primary predictor of the magnitude of the antipredator response. Given the tight relationship between predator distance and prey movement and the important role herbivores can play, particularly in this ecosystem, we expect that NCEs will cascade to the patterns of abundance and composition of rocky shore communities through changes in prey foraging behavior under risk.
Año: 2018
Palabras claves: antipredator behavior, escape, non‐consumptive effects, predator detection behavior, predator–prey interactions, rocky inter‐tidal, spatial scale
Referencia APA: Manzur, T., Gonzalez-Mendez, A. and Broitman, B. (2018). Scales of predator detection behavior and escape in Fissurella limbata: A field and laboratory assessment. Marine Ecology, 39(2), p.e12492. https://doi.org/10.1111/maec.12492
Metagenomic exploration of soils microbial communities associated to Antarctic vascular plants
Molina-Montenegro, M., Ballesteros, G., Castro-Nallar, E., Meneses, C., Torres-Díaz, C. and Gallardo-Cerda, J.
Antarctica is one of the most stressful ecosystems worldwide with few vascular plants,which are limited by abiotic conditions. Here, plants such as Deschampsia antarctica (Da)could generate more suitable micro-environmental conditions for the establishment ofother plants as Colobanthus quitensis (Cq). Although, plant-plant interaction is known todetermine the plant performance, little is known about how microorganisms mightmodulate the ability of plants to cope with stressful environmental conditions. Severalreports have focused on the possible ecological roles of microorganism with vascularplants, but if the rizospheric microorganisms can modulate the positive interactions amongvascular Antarctic plants has been seldom assessed. In this study, we compared therhizosphere microbiomes associated with Cq, either growing alone or associated with Da,using a shotgun metagenomic DNA sequencing approach and using eggNOG forcomparative and functional metagenomics. Overall, results show higher diversity oftaxonomic and functional groups in rhizospheric soil from Cq+Da than Cq. On the otherhand, functional annotation shows that microorganisms from rhizospheric soil from Cq+Dahave a significantly higher representation of genes associated to metabolic functionsrelated with environmental stress tolerance than Cq soils. Additional research is needed toexplore both the biological impact of these higher activities in terms of gene transfer onplant performance and in turn help to explain the still unsolved enigma about the strategydeployed by Cq to inhabit and cope with harsh conditions prevailing in Antarctic.
Año: 2018
Palabras claves:
Referencia APA: Molina-Montenegro, M., Ballesteros, G., Castro-Nallar, E., Meneses, C., Torres-Díaz, C. and Gallardo-Cerda, J. (2018). Metagenomic exploration of soils microbial communities associated to Antarctic vascular plants.
Temporal Variability of MODIS Phenological Indices in the Temperate Rainforest of Northern Patagonia
Lara, C., Saldías, G., Paredes, A., Cazelles, B. and Broitman, B.
Western Patagonia harbors unique and sparsely studied terrestrial ecosystems that are threatened by land use changes and exposure to basin-scale climatic variability. We assessed the performance of two satellite vegetation indices derived from MODIS–Terra, EVI (Enhanced Vegetation Index) and NDVI (Normalized Difference Vegetation Index), over the northern and southern sectors of the Chiloé Island System (CIS) to advance our understanding of vegetation dynamics in the region. Then we examined their time-varying relationships with two climatic indices indicative of tropical and extratropical influence, the ENSO (El Niño–Southern Oscillation) and the Antarctic Oscillation (AAO) index, respectively. The 17-year time series showed that only EVI captured the seasonal pattern characteristic of temperate regions, with low (high) phenological activity during Autumn-Winter (Spring–Summer). NDVI saturated during the season of high productivity and failed to capture the seasonal cycle. Temporal patterns in productivity showed a weakened seasonal cycle during the past decade, particularly over the northern sector. We observed a non-stationary association between EVI and both climatic indices. Significant co-variation between EVI and the Niño–Southern Oscillation index in the annual band persisted from 2001 until 2008–2009; annual coherence with AAO prevailed from 2013 onwards and the 2009–2012 period was characterized by coherence between EVI and both climate indices over longer temporal scales. Our results suggest that the influence of large-scale climatic variability on local weather patterns drives phenological responses in the northern and southern regions of the CIS. The imprint of climatic variability on patterns of primary production across the CIS may be underpinned by spatial differences in the anthropogenic modification of this ecosystem, as the northern sector is strongly modified by forestry and agriculture. We highlight the need for field validation of satellite indices around areas of high biomass and high endemism, located in the southern sector of the island, in order to enhance the utility of satellite vegetation indices in the conservation and management of austral ecosystems.
Año: 2018
Palabras claves: MODIS; primary productivity; climatic variability; vegetation index; wavelet coherence
Referencia APA: Lara, C., Saldías, G., Paredes, A., Cazelles, B. and Broitman, B. (2018). Temporal Variability of MODIS Phenological Indices in the Temperate Rainforest of Northern Patagonia. Remote Sensing, 10(6), p.956. https://doi.org/10.3390/rs10060956
Asymmetric connectivity of the lobster Panulirus pascuensis in remote islands of the southern Pacific: importance for its management and conservation
Meerhoff, E., Yannicelli, B., Dewitte, B., Díaz-Cabrera, E., Vega-Retter, C., Ramos, M., Bravo, L., Concha, E., Hernández-Vaca, F. and Véliz, D.
Understanding patterns of marine connectivity in oceanic islands is a fundamental element for conservation and management of fished species. In the present study, the level of connectivity of the endemic lobster Panulirus pascuensis Reed, 1954 from remote islands in the southern Pacific Ocean was estimated, focusing on the Motu Motiro Hiva Marine Park (MMH), considered here as a source of recruits to Easter Island. The connectivity of adult lobster populations between Eastern Island (EI) and Salas y Gómez Island (SG), in the center of MMH, was studied by quantifying the reciprocal migration rates using variability of microsatellite loci and a biophysical individual-based model of larval transport based on the outputs of a regional high-resolution oceanic model. Considering a system composed only of adult populations located in both islands, the genetic analysis showed that 3% of the adults from EI came from SG; however, only 0.02% in the opposite direction. Neglecting the effect of other islands (e.g., Pitcairn Island located at 2000 km west of EI), the self-recruitment was estimated at 97% in EI and 99.8% in SG. The results of the Lagrangian analysis of the oceanic model simulations are consistent with the concept of asymmetric connectivity, although there is appreciable variation in recruitment among years. Both genetic and oceanographic approaches revealed large variance in connectivity from SG to EI. The asymmetric connectivity from SG to EI emphasizes the importance of the MMH Marine Park for lobster conservation in SG, and that it also supports recruitment of P. pascuensis to EI.
Año: 2018
Palabras claves:
Referencia APA: Meerhoff, E., Yannicelli, B., Dewitte, B., Díaz-Cabrera, E., Vega-Retter, C., Ramos, M., Bravo, L., Concha, E., Hernández-Vaca, F. and Véliz, D. (2018). Asymmetric connectivity of the lobster Panulirus pascuensis in remote islands of the southern Pacific: importance for its management and conservation. Bulletin of Marine Science, 94(3), pp.753-774. https://doi.org/10.5343/bms.2017.1114
Phenotypic plasticity at the edge: Contrasting population‐level responses at the overlap of the leading and rear edges of the geographical distribution of two Scurria limpets
Broitman, B., Aguilera, M., Lagos, N. and Lardies, M.
Aim
To examine the role of ocean temperature and chemistry as drivers of interpopulation differences in multiple phenotypic traits between rear and leading edge populations of two species of limpet.
Location
The coast of north‐central Chile, western South America.
Taxon
Mollusca, Gastropoda (Lottidae).
Methods
We used field and laboratory experiments to study the ecology and physiology of individuals from populations located at the overlap of the rear and leading edges of their respective geographical distributions. At the same time, we characterized local environmental regimes, measuring seawater physical and chemical properties.
Results
Towards the edge of their range, individuals from the leading edge species gradually reduced their shell length, metabolic rate and thermal response capacity, and increased carbonate content in their shells. Individuals of the rear edge species showed dissimilar responses between sites. Contrasting behavioural responses to experimental heating reconciled observations of an unintuitive higher maximal critical temperature and a smaller thermal safety margin for individuals of the rear edge populations. Physical–chemical characterization of seawater properties at the site located on the core of the upwelling centre showed extreme environmental conditions, with low oxygen concentration, high pCO2 and the episodic presence of corrosive seawater. These challenging environmental conditions were reflected in reduced growth for both species.
Main conclusions
We found different spatial patterns of phenotypic plasticity in two sister species around the leading and trailing edges of their distributions. Our results provide evidence that environmental conditions around large upwelling centres can maintain biogeographical breaks through metabolic constraints on the performance of calcifying organisms. Thus, local changes in seawater chemistry associated with coastal upwelling circulation emerge as a previously overlooked driver of marine range edges.
Año: 2018
Palabras claves: biogeographical break, calcification, limpet, Scurria, SE Pacific, thermal physiology, upwelling
Referencia APA: Broitman, B., Aguilera, M., Lagos, N. and Lardies, M. (2018). Phenotypic plasticity at the edge: Contrasting population‐level responses at the overlap of the leading and rear edges of the geographical distribution of two Scurria limpets. Journal of Biogeography, 45(10), pp.2314-2325. https://doi.org/10.1111/jbi.13406
Isolation and characterization of Pb-solubilizing bacteria and their effects on Pb uptake by Brassica juncea: implications for microbe-assisted phytoremediation
Yahaghi, Z., Shirvani, M., Nourbakhsh, F., de la Peña, T.C., Pueyo, J.J., Talebi, M.
The aim of this study was to isolate and characterize lead (Pb)-solubilizing bacteria from heavy metal-contaminated mine soils and to evaluate their inoculation effects on the growth and Pb absorption of Brassica juncea. The isolates were also evaluated for their plant growth-promoting characteristics as well as heavy metal and salt tolerance. A total of 171 Pb-tolerant isolates were identified, of which only 15 bacterial strains were able to produce clear haloes in solid medium containing PbO or PbCO3, indicating Pb solubilization. All of these 15 strains were also able to dissolve the Pb minerals in a liquid medium, which was accompanied by significant decreases in pH values of the medium. Based on 16S rRNA gene sequence analysis, the Pb-solubilizing strains belonged to genera Bacillus, Paenibacillus, Brevibacterium, and Staphylococcus. A majority of the Pb-solubilizing strains were able to produce indole acetic acid and siderophores to different extents. Two of the Pb-solubilizing isolates were able to solubilize inorganic phosphate as well. Some of the strains displayed tolerance to different heavy metals and to salt stress and were able to grow in a wide pH range. Inoculation with two selected Pb-solubilizing and plant growth-promoting strains, (i.e., Brevibacterium frigoritolerans YSP40 and Bacillus paralicheniformis YSP151) and their consortium enhanced the growth and Pb uptake of B. juncea plants grown in a metal-contaminated soil. The bacterial strains isolated in this study are promising candidates to develop novel microbe-assisted phytoremediation strategies for metal-contaminated soils.
Año: 2018
Palabras claves: Metal-solubilizing bacteria, PGPR, contaminated soils, lead, phytoremediation
Referencia APA: Yahaghi, Z., Shirvani, M., Nourbakhsh, F., de la Peña, T.C., Pueyo, J.J., Talebi, M. (2018). Isolation and characterization of Pb-solubilizing bacteria and their effects on Pb uptake by Brassica juncea: implications for microbe-assisted phytoremediation. https://doi.org/10.4014/jmb.1712.12038
Decoding the gene coexpression network underlying the ability of Gevuina avellana to live in diverse light conditions
Ostria-Gallardo, E., Ranjan, A., Ichihashi, Y., Corcuera, L., & Sinha, N.
Gevuina avellana (Proteaceae) is a typical tree from the South American temperate rainforest. Although this species mostly regenerates in shaded understories, it exhibits an exceptional ecological breadth, being able to live under a wide range of light conditions. Here we studied the genetic basis that underlies physiological acclimation of the photosynthetic responses of G. avellana under contrasting light conditions.
We analyzed carbon assimilation and light energy used for photochemical processes in plants acclimated to contrasting light conditions. Also, we used a transcriptional profile of leaf primordia from G. avellana saplings growing under different light environments in their natural habitat, to identify the gene coexpression network underpinning photosynthetic performance and light‐related processes.
The photosynthetic parameters revealed optimal performance regardless of light conditions. Strikingly, the mechanism involved in dissipation of excess light energy showed no significant differences between high‐ and low‐light‐acclimated plants. The gene coexpression network defined a community structure consistent with the photochemical responses, including genes involved mainly in assembly and functioning of photosystems, photoprotection, and retrograde signaling.
This ecophysiological genomics approach improves our understanding of the intraspecific variability that allows G. avellana to have optimal photochemical and photoprotective mechanisms in the diverse light habitats it encounters in nature.
Año: 2018
Palabras claves: Gene coexpression network, Gevuina avellana, light acclimation, photosynthesis, temperate rainforest
Referencia APA: Ostria-Gallardo, E., Ranjan, A., Ichihashi, Y., Corcuera, L., & Sinha, N. (2018). Decoding the gene coexpression network underlying the ability of Gevuina avellana to live in diverse light conditions. New Phytologist, 220(1), 278-287. doi: 10.1111/nph.15278
Antarctic rhizobacteria improve salt tolerance and physiological performance of the Antarctic vascular plants
Gallardo-Cerda, J., Levihuan, J., Lavín, P., Oses, R., Atala, C., & Torres-Díaz, C., Cuba-Díaz, M., Barrera, A., Molina-Montenegro, M.A.
The two native Antarctic vascular plants, Deschampsia antarctica and Colobanthus quitensis, are mostly restricted to coastal habitats where they are often exposed to sea spray with high levels of salinity. Most of the studies regarding the ability of C. quitensis and D. antarctica to cope with abiotic stress have been focused on their physiological adaptations to tolerate cold stress, but little is known about their tolerance to salinity. We investigated whether rhizospheric bacteria associated to D. antarctica and C. quitensis improve the ability of Antarctic plants to tolerate salt stress. Salt tolerance was assayed in rhizospheric bacteria, and also their effects on the ecophysiological performance (photochemical efficiency of PSII, growth, and survival) of both plants were assessed under salt stress. A total of eight bacterial rhizospheric strains capable of growing at 4 °C were isolated. The strains isolated from D. antarctica showed higher levels of salt tolerance than those strains isolated from C. quitensis. The ecophysiological performance of C. quitensis and D. antarctica was significantly increased when plants were inoculated with rhizospheric bacteria. Our results suggest that rhizospheric bacteria improve the ability of both plants to tolerate salinity stress with positive effects on the adaptation and survival of vascular plants to current conditions in Antarctic ecosystem.
Año: 2018
Palabras claves: Salt tolerance, Antarctica, Plant growth-promoting rhizobacteria, Colobanthus quitensis, Deschampsia antarctica
Referencia APA: Gallardo-Cerda, J., Levihuan, J., Lavín, P., Oses, R., Atala, C., & Torres-Díaz, C., Cuba-Díaz, M., Barrera, A., Molina-Montenegro, M.A. (2018). Antarctic rhizobacteria improve salt tolerance and physiological performance of the Antarctic vascular plants. Polar Biology, 41(10), 1973-1982. doi: 10.1007/s00300-018-2336-z
Decadal modulation of the relationship between intraseasonal tropical variability and ENSO
Guschina, D., Dewitte, B.
The El Niño Southern Oscillation (ENSO) amplitude is modulated at decadal timescales, which, over the last decades, has been related to the low-frequency changes in the frequency of occurrence of the two types of El Niño events, that is the Eastern Pacific (EP) and Central Pacific (CP) El Niños. Meanwhile ENSO is tightly linked to the intraseasonal tropical variability (ITV) that is generally enhanced prior to El Niño development and can act as a trigger of the event. Here we revisit the ITV/ENSO relationship taking into account changes in ENSO properties over the last six decades. The focus is on two main components of ITV, the Madden–Julian Oscillation (MJO) and convectively coupled equatorial Rossby waves (ER). We show that the ITV/ENSO relationship exhibits a decadal modulation that is not related in a straight-forward manner to the change in occurrence of El Niño types and Pacific decadal modes. While enhanced MJO activity associated to EP El Niño development mostly took place over the period 1985–2000, the ER activity is enhanced prior to El Niño development over the whole period with a tendency to relate more to CP El Niño than to EP El Niño. In particular the relationship between ER activity and ENSO was particularly strong for the period 2000–2015, which results in a significant positive long-term trend of the predictive value of ER activity. The statistics of the MJO and ER activity is consistent with the hypothesis that they can be considered a state-dependent noise for ENSO linked to distinct lower frequency climate modes.
Año: 2018
Palabras claves: Intraseasonal tropical variability, El Niño, Decadal modulation
Referencia APA: Gushchina, D., & Dewitte, B. (2018). Decadal modulation of the relationship between intraseasonal tropical variability and ENSO. Climate Dynamics. doi: 10.1007/s00382-018-4235-y
Decadal modulation of the relationship between intraseasonal tropical variability and ENSO
Gushchina, D., & Dewitte, B.
The El Niño Southern Oscillation (ENSO) amplitude is modulated at decadal timescales, which, over the last decades, has been related to the low-frequency changes in the frequency of occurrence of the two types of El Niño events, that is the Eastern Pacific (EP) and Central Pacific (CP) El Niños. Meanwhile ENSO is tightly linked to the intraseasonal tropical variability (ITV) that is generally enhanced prior to El Niño development and can act as a trigger of the event. Here we revisit the ITV/ENSO relationship taking into account changes in ENSO properties over the last six decades. The focus is on two main components of ITV, the Madden–Julian Oscillation (MJO) and convectively coupled equatorial Rossby waves (ER). We show that the ITV/ENSO relationship exhibits a decadal modulation that is not related in a straight-forward manner to the change in occurrence of El Niño types and Pacific decadal modes. While enhanced MJO activity associated to EP El Niño development mostly took place over the period 1985–2000, the ER activity is enhanced prior to El Niño development over the whole period with a tendency to relate more to CP El Niño than to EP El Niño. In particular the relationship between ER activity and ENSO was particularly strong for the period 2000–2015, which results in a significant positive long-term trend of the predictive value of ER activity. The statistics of the MJO and ER activity is consistent with the hypothesis that they can be considered a state-dependent noise for ENSO linked to distinct lower frequency climate modes.
Año: 2018
Palabras claves: Intraseasonal tropical variability, El Niño, Decadal modulation
Referencia APA: Gushchina, D., & Dewitte, B. (2018). Decadal modulation of the relationship between intraseasonal tropical variability and ENSO. Climate Dynamics. doi: 10.1007/s00382-018-4235-y
Seasonal variability of the Ekman transport and pumping in the upwelling system off central-northern Chile (∼ 30° S) based on a high-resolution atmospheric regional model
Bravo, L., Ramos, M., Astudillo, O., Dewitte, B., & Goubanova, K.
Two physical mechanisms can contribute to coastal upwelling in eastern boundary current systems: offshore Ekman transport due to the predominant alongshore wind stress and Ekman pumping due to the cyclonic wind stress curl, mainly caused by the abrupt decrease in wind stress (drop-off) in a cross-shore band of 100 km. This wind drop-off is thought to be an ubiquitous feature in coastal upwelling systems and to regulate the relative contribution of both mechanisms. It has been poorly studied along the central-northern Chile region because of the lack in wind measurements along the shoreline and of the relatively low resolution of the available atmospheric reanalysis. Here, the seasonal variability in Ekman transport, Ekman pumping and their relative contribution to total upwelling along the central-northern Chile region (∼ 30° S) is evaluated from a high-resolution atmospheric model simulation. As a first step, the simulation is validated from satellite observations, which indicates a realistic representation of the spatial and temporal variability of the wind along the coast by the model. The model outputs are then used to document the fine-scale structures in the wind stress and wind curl in relation to the topographic features along the coast (headlands and embayments). Both wind stress and wind curl had a clear seasonal variability with annual and semiannual components. Alongshore wind stress maximum peak occurred in spring, second increase was in fall and minimum in winter. When a threshold of −3 × 10−5 s−1 for the across-shore gradient of alongshore wind was considered to define the region from which the winds decrease toward the coast, the wind drop-off length scale varied between 8 and 45 km. The relative contribution of the coastal divergence and Ekman pumping to the vertical transport along the coast, considering the estimated wind drop-off length, indicated meridional alternation between both mechanisms, modulated by orography and the intricate coastline. Roughly, coastal divergence predominated in areas with low orography and headlands. Ekman pumping was higher in regions with high orography and the presence of embayments along the coast. In the study region, the vertical transport induced by coastal divergence and Ekman pumping represented 60 and 40 % of the total upwelling transport, respectively. The potential role of Ekman pumping on the spatial structure of sea surface temperature is also discussed.
Año: 2016
Palabras claves:
Referencia APA: Bravo, L., Ramos, M., Astudillo, O., Dewitte, B., & Goubanova, K. (2016). Seasonal variability of the Ekman transport and pumping in the upwelling system off central-northern Chile (∼ 30° S) based on a high-resolution atmospheric regional model (WRF). Ocean Science, 12(5), 1049-1065. http://dx.doi.org/10.5194/os-12-1049-2016