Symbiotic Interaction Enhances the Recovery of Endangered Tree Species in the Fragmented Maulino Forest

Autores:

Torres-Díaz C, Valladares MA, Acuña-Rodríguez IS, Ballesteros GI, Barrera A, Atala C and Molina-Montenegro MA

Resumen:

Beneficial plant-associated microorganisms, such as fungal endophytes, are key partners that normally improve plant survival under different environmental stresses. It has been shown that microorganisms from extreme environments, like those associated with the roots of Antarctica plants, can be good partners to increase the performance of crop plants and to restore endangered native plants. Nothofagus alessandrii and N. glauca, are among the most endangered species of Chile, restricted to a narrow and/or limited distributional range associated mainly to the Maulino forest in Chile. Here we evaluated the effect of the inoculation with a fungal consortium of root endophytes isolated from the Antarctic host plant Colobanthus quitensis on the ecophysiological performance [photosynthesis, water use efficiency (WUE), and growth] of both endangered tree species. We also, tested how Antarctic root-fungal endophytes could affect the potential distribution of N. alessandrii through niche modeling. Additionally, we conducted a transplant experiment recording plant survival on 2 years in order to validate the model. Lastly, to evaluate if inoculation with Antarctic endophytes has negative impacts on native soil microorganisms, we compared the biodiversity of fungi and bacterial in the rhizospheric soil of transplanted individuals of N. alessandrii inoculated and non-inoculated with fungal endophytes. We found that inoculation with root-endophytes produced significant increases in N. alessandrii and N. glauca photosynthetic rates, water use efficiencies and cumulative growth. In N. alessandrii, seedling survival was significantly greater on inoculated plants compared with non-inoculated individuals. For this species, a spatial distribution modeling revealed that, inoculation with root-fungal endophytes could potentially increase the current distributional range by almost threefold. Inoculation with root-fungal endophytes, did not reduce native rhizospheric microbiome diversity. Our results suggest that the studied consortium of Antarctic root-fungal endophytes improve the ecophysiological performance as well as the survival of inoculated trees and can be used as a biotechnological tool for the restoration of endangered tree species.

Año: 2021

Palabras claves: Nothofagus spp., ruil, hualo, endangered tree species, restoration, Antarctica, fungal endophytes, functional symbiosis

Genotoxicity of oxidative stress and UV-B radiation in Antarctic vascular plants

Autores:

Acuña-Rodríguez, I.S., Zúñiga-Venegas, L.A. & Molina-Montenegro, M.A.

Resumen:

For plants, reactive oxygen species (ROS) and ultraviolet B radiation (UV-B) stand out as important genotoxic agents. Hence, the genetic damage among the Antarctic vascular flora, whose individuals frequently experience these abiotic stresses, might be recurrent among their populations. To respond this, the genetic damage associated with these stress factors was evaluated in Colobanthus quitensis and Deschampsia antarctica for the first time in the field and compared with those showed by plants grown at laboratory under less stressful conditions. Fifteen individuals per species from Admiralty Bay populations at King George Island (Maritime Antarctica) were used to semi-quantitatively estimate the genetic damage at the whole genome level by the single-cell gel electrophoresis (SCGE) assay, revealing by means of specific enzymatic treatments the damage generated by oxidative stress (oxidized purines and pyrimidines) and UV-B radiation (pyrimidine dimmers). Compared with laboratory control individuals, the basal genetic damage observed in both species was significantly higher under field conditions. However, while for C. quitensis, oxidative stress (Ox) was more relevant than UV-B radiation (field relative revealed damage: Ox = 29% vs. UV-B = 25%), in D. antarctica, it was UV-B radiation the most relevant genotoxic factor (Ox = 10% vs. UV-B = 33%). This first approach to the genetic damage of the Antarctic vascular flora suggests that the conditions experienced on their natural ecosystems would constitute a genotoxic environment for these species, yet with differential impact between them.

Año: 2021

Palabras claves: Antarctic plants, Comet assay, DNA damage, Oxidative stress, UV-B radiation

Global Plastic Pollution Observation System to Aid Policy

Autores:

Bank, M.S., Swarzenski, P.W., Duarte, C.M., Rillig, M.C., Koelmans, A.A., Metian, M., Wright, S., Provencher, J.F., Sanden, M., Jordaan, A., Wagner, M., Thiel, M, and Ok, Y.S.

Resumen:

Plastic pollution has become one of the most pressing environmental challenges and has received commensurate widespread attention. Although it is a top priority for policymakers and scientists alike, the knowledge required to guide decisions, implement mitigation actions, and assess their outcomes remains inadequate. We argue that an integrated, global monitoring system for plastic pollution is needed to provide comprehensive, harmonized data for environmental, societal, and economic assessments. The initial focus on marine ecosystems has been expanded here to include atmospheric transport and terrestrial and freshwater ecosystems. An earth-system-level plastic observation system is proposed as a hub for collecting and assessing the scale and impacts of plastic pollution across a wide array of particle sizes and ecosystems including air, land, water, and biota and to monitor progress toward ameliorating this problem. The proposed observation system strives to integrate new information and to identify pollution hotspots (i.e., production facilities, cities, roads, ports, etc.) and expands monitoring from marine environments to encompass all ecosystem types. Eventually, such a system will deliver knowledge to support public policy and corporate contributions to the relevant United Nations (UN) Sustainable Development Goals (SDGs).

Año: 2021

Palabras claves: Public policy monitoring reporting plastic waste pollution ecosystem.

Evaluating optically stimulated luminescence rock surface exposure dating as a novel approach for reconstructing coastal boulder movement on decadal to centennial timescales

Autores:

Brill, D., May, S. M., Mhammdi, N., King, G., Lehmann, B., Burow, C., Wolf, D., Zander, A., and Brückner, H.

Resumen:

Wave-transported boulders represent important records of storm and tsunami impact over geological timescales. Their use for hazard assessment requires chronological information on their displacement that in many cases cannot be achieved by established dating approaches. To fill this gap, this study investigated, for the first time, the potential of optically stimulated luminescence rock surface exposure dating (OSL-RSED) for estimating cliff-detachment ages of wave-transported coastal boulders. The approach was tested on calcarenite clasts at the Rabat coast, Morocco. Calibration of the OSL-RSED model was based on samples with rock surfaces exposed to sunlight for ∼ 2 years, and OSL exposure ages were evaluated against age control deduced from satellite images. Our results show that the dating precision is limited for all targeted boulders due to the local source rock lithology which has low amounts of quartz and feldspar. The dating accuracy may be affected by erosion rates on boulder surfaces of 0.02–0.18 mm yr−1. Nevertheless, we propose a robust relative chronology for boulders that are not affected by significant post-depositional erosion and that share surface angles of inclination with the calibration samples. The relative chronology indicates that (i) most boulders were detached from the cliff by storm waves; (ii) these storms lifted boulders with masses of up to ∼ 24 t; and (iii) the role of storms in the formation of boulder deposits along the Rabat coast is more significant than previously assumed. Although OSL-RSED cannot provide reliable absolute exposure ages for the coastal boulders in this study, the approach has large potential for boulder deposits composed of rocks with larger amounts of quartz or feldspar and less susceptibility to erosion.

Año: 2021

Palabras claves:

Getting ready for the ozone battle: Vertically transmitted fungal endophytes have transgenerational positive effects in plants

Autores:

Ueno, A.C, Gundel, P.E., Molina-Montenegro, M.A., Ramos, P., Ghersa, C.M., Martínez-Ghersa, M.A.

Resumen:

Ground-level ozone is a global air pollutant with high toxicity and represents a threat to plants and microorganisms. Although beneficial microorganisms can improve host performance, their role in connecting environmentally induced maternal plant phenotypes to progeny (transgenerational effects [TGE]) is unknown. We evaluated fungal endophyte-mediated consequences of maternal plant exposure to ozone on performance of the progeny under contrasting scenarios of the same factor (high and low) at two stages: seedling and young plant. With no variation in biomass, maternal ozone-induced oxidative damage in the progeny that was lower in endophyte-symbiotic plants. This correlated with an endophyte-mediated higher concentration of proline, a defence compound associated with stress control. Interestingly, ozone-induced TGE was not associated with reductions in plant survival. On the contrary, there was an overall positive effect on seedling survival in the presence of endophytes. The positive effect of maternal ozone increasing young plant survival was irrespective of symbiosis and only expressed under high ozone condition. Our study shows that hereditary microorganisms can modulate the capacity of plants to transgenerationally adjust progeny phenotype to atmospheric change.

Año: 2021

Palabras claves:

Tracing trophic pathways through the marine ecosystem of Rapa Nui (Easter Island)

Autores:

Zapata‐Hernández, G., Sellanes, J., Letourneur, Y., Harrod, C., Morales, N.A., Plaza, P., Meerhoff, E., Yannicelli, B., Carrasco, S.A., Hinojosa, I., Gaymer, C.F.

Resumen:

The structure of food webs provides important insight into biodiversity, organic matter (OM) pathways, and ecosystem functioning.

Stable isotope analysis (δ13C and δ15N) was used to characterize the trophic structure and the main OM pathways supporting food webs in the Rapa Nui coastal marine ecosystem.

The trophic position of consumers and isotopic niche metrics were estimated for different assemblages (i.e. mesozooplankton, emergent zooplankton, reef invertebrates, reef fishes, pelagic fishes, and seabirds). Furthermore, the relative importance of different OM sources (i.e. macroalgae, zooxanthellate corals, and particulate OM [POM]) was assessed for heterotrophic consumers using Bayesian mixing model (MixSIAR).

Results show a clear pattern of 13C and 15N enrichment from small‐sized pelagic and benthic invertebrates, to reef and pelagic fishes, and seabirds. Most invertebrates were classified as primary consumers, reef fishes as secondary consumers and pelagic predators and seabirds as tertiary and quaternary consumers.

Isotopic niche metrics indicate a low trophic diversity for pelagic assemblages (mesozooplankton and pelagic fishes), in contrast to reef fauna (invertebrates and fishes), whose higher trophic diversity suggest the exploitation of a wider range of trophic resources. Overlapping of standard ellipses areas between reef invertebrates and reef fishes indicates that both assemblages could be sharing trophic resources.

Mixing models results indicate that POM is the main trophic pathway for mesozooplankton, macroalgae (Rhodophyta) for emergent zooplankton, and a mix of coral‐derived OM and Rhodophyta for coral reef assemblages such as macrobenthos and reef invertebrates. In contrast, POM contribution was notably more important for some pelagic fishes and seabirds from upper trophic levels.

This study provides key elements for conservation efforts on coral reefs, management planning and full‐implementation of the recently created Rapa Nui Multiple Use Marine Protected Area.

Año: 2021

Palabras claves: Coral reefs, cryptic fauna, food web, mixing models, organic matter fluxes, stable isotopes, subtropical South Pacific, trophic position, trophic structure.

Evaluating optically stimulated luminescence rock surface exposure dating as a novel approach for reconstructing coastal boulder movement on decadal to centennial timescales

Autores:

Brill, D., May, S. M., Mhammdi, N., King, G., Lehmann, B., Burow, C., Wolf, D., Zander, A., and Brückner, H.

Resumen:

Wave-transported boulders represent important records of storm and tsunami impact over geological timescales. Their use for hazard assessment requires chronological information on their displacement that in many cases cannot be achieved by established dating approaches. To fill this gap, this study investigated, for the first time, the potential of optically stimulated luminescence rock surface exposure dating (OSL-RSED) for estimating cliff-detachment ages of wave-transported coastal boulders. The approach was tested on calcarenite clasts at the Rabat coast, Morocco. Calibration of the OSL-RSED model was based on samples with rock surfaces exposed to sunlight for ∼ 2 years, and OSL exposure ages were evaluated against age control deduced from satellite images. Our results show that the dating precision is limited for all targeted boulders due to the local source rock lithology which has low amounts of quartz and feldspar. The dating accuracy may be affected by erosion rates on boulder surfaces of 0.02–0.18 mm yr−1. Nevertheless, we propose a robust relative chronology for boulders that are not affected by significant post-depositional erosion and that share surface angles of inclination with the calibration samples. The relative chronology indicates that (i) most boulders were detached from the cliff by storm waves; (ii) these storms lifted boulders with masses of up to ∼ 24 t; and (iii) the role of storms in the formation of boulder deposits along the Rabat coast is more significant than previously assumed. Although OSL-RSED cannot provide reliable absolute exposure ages for the coastal boulders in this study, the approach has large potential for boulder deposits composed of rocks with larger amounts of quartz or feldspar and less susceptibility to erosion.

Año: 2021

Palabras claves:

Mining and Industrial Uses

Autores:

Duhalde D., Castillo D., Oyarzún R., Oyarzún J., Arumí J.L.

Resumen:

This chapter addresses the relationship between water resources and important economic activities in Chile, particularly mining and the manufacturing industry. This assessment involves aspects related to the importance of these industries in the Chilean economy, their water demand throughout the country, associated environmental impacts and, finally, the challenges faced by these sectors in terms of the sustainable use of water resources. To understand the interactions between the aforementioned economic activities and water, one must first consider the climate heterogeneity of Chile. The north of the country has a desert climate while the south is becoming increasingly rainy. On the other hand, mining activity takes place mainly in the area of the country with the greatest water scarcity, while the manufacturing industry is highly diversified throughout Chile. The direct options available to these sectors for achieving sustainable water management are centered on the use of more and better technologies related to recirculation of process water and the use of seawater.

Año: 2021

Palabras claves: Mining, Industry, Water scarcity, Uses, Recirculation, Seawater

The Humboldt Current Large Marine Ecosystem (HCLME), a Challenging Scenario for Modelers and Their Contribution for the Manager

Autores:

Chevallier A., Stotz W., Ramos M., Mendo J.

Resumen:

The Humboldt Current Large Marine Ecosystem (HCLME) is a salient feature of the southeastern Pacific, along the South American coast of Chile and Peru. It is associated with coastal upwelling which generates a very productive ecosystem. However, due to a variety of interconnected biophysical processes at diverse temporal and spatial scales, production varies greatly in time and space. The interplay of the biophysical environment, biological processes involving valuable resources on international markets, the socio-political context, and some management decisions, has shaped the daily life of the HCLME fisheries, marked by booms and busts, offering wealth for short periods of time, followed by collapses. These collapses are generally interpreted as the consequence of a lack of appropriate management, so that a variety of increasingly stricter regulations have been implemented. Nevertheless, this has not significantly reduced the temporal variability of the fisheries landings, which is broadly characterized by a peaks and troughs pattern. While the HCLME is one of the most productive marine ecosystems on Earth, along with a great biophysical and biological variability, it is also a huge but fragile exploited social-ecological system. Modelers can help to understand how to continuously adapt in order to deal with recurrent fisheries “crises,” which, as we are beginning to learn, may simply be an expression of the variability inherent in this complex system. Furthermore, it is essential to increase our capacity to adapt to the expected consequences of climate change.

Año: 2021

Palabras claves:

Climate models capture key features of extreme precipitation probabilities across regions

Autores:

Cristian Martinez-Villalobos and J David Neelin

Resumen:

Quantitative simulation of precipitation in current climate has been an ongoing challenge for global climate models. Despite serious biases in correctly simulating probabilities of extreme rainfall events, model simulations under global warming scenarios are routinely used to provide estimates of future changes in these probabilities. To minimize the impact of model biases, past literature tends to evaluate fractional (instead of absolute) changes in probabilities of precipitation extremes under the assumption that fractional changes would be more reliable. However, formal tests for the validity of this assumption have been lacking. Here we evaluate two measures that address properties important to the correct simulation of future fractional probability changes of precipitation extremes, and that can be assessed with current climate data. The first measure tests climate model performance in simulating the characteristic shape of the probability of occurrence of daily precipitation extremes and the second measure tests whether the key parameter governing the scaling of this shape is well reproduced across regions and seasons in current climate. Contrary to concerns regarding the reliability of global models for extreme precipitation assessment, our results show most models lying within the current range of observational uncertainty in these measures. Thus, most models in the Coupled Model Intercomparison Project Phase 6 ensemble pass two key tests in current climate that support the usefulness of fractional measures to evaluate future changes in the probability of precipitation extremes.

Año: 2021

Palabras claves: