Eco-hydro-morphological evolution of river basins affected by volcanic eruptions in southern Chile: a conceptual model and a risk management approach

ABSTRACT Freshwater crayfishes of the South American family Parastacidae include the Chilean‐endemic genus Virilastacus , currently comprising four described species. Despite their ecological importance and restricted distributions, the genetic diversity, phylogenetic relationships, and species boundaries within Virilastacus remain poorly understood. Here, we analyze mitochondrial DNA (COI) sequences from populations across the genus's known range in southern Chile to assess species limits, divergence times, and geographic structure. Phylogenetic analyses and multiple single‐locus species delimitation methods support the identification of five candidate species, comprising the four currently recognised species and a newly identified lineage, Virilastacus sp. ‘Calfuco’. Divergence time estimates place the origin of Virilastacus in the Middle Oligocene, indicating an ancient evolutionary history. We also report an expanded range for V. jarai , a narrower distribution for V. araucanius , and strong geographic structuring across the genus. These findings highlight previously overlooked diversity in Virilastacus and emphasise the need for further integrative taxonomic and conservation assessments.

The city of Valdivia, one of the most important cities in southern Chile, presents a complex morphology, which has defined the process of transformation and occupation that this manuscript intends to explore. Based on the Florence Coefficient of Localisation (FCL), we propose a study of the polycentric structure of Valdivia based on its exceptional situation as a medium-sized city, located in the middle of a system of rivers and wetlands. The paper provides, first, a historical vision of the relationship between nature and the city that exists in Valdivia, highlighting the residential value currently attributed to bodies of water, along with their relevance for the development of State-subsidized housing projects. The contemporary tensions noted from the methodology used allow us to explore, in terms of the Florence Location Coefficient, the structural qualities in each of the city’s neighbourhoods, which are analysed in terms of effects and opportunities associated with the current policies of territorial and social integration to produce housing subsidized by the State, this time, within the framework of a complex urban space in Chile.

Molecular evidence of Mycobacterium avium subspecies paratuberculosis (MAP) shedding in the invasive American mink (Neogale vison) in southern Chile.

Pelseria S.E.Freire & Urtubey, a new monotypic genus, is described to accommodate Senecio otites from S. sect. Otites. The new genus is a perennial herb with large petiolate leaves and auriculate stipules, occurring in southern Argentina and Chile. The style morphology of Pelseria resembles that of Dendrophorbium and Hoehnephytum due to the subconvex style tips with short sweeping-hairs. Molecular evidence from nuclear and plastid DNA sequences place Pelseria in a clade with Graphistylis dichroa, Hoehnephytum trixoides, Dendrophorbium bomanii, and Arbelaezaster ellsworthii. A key to the similar genera found in Argentina and Chile is provided, as well as a distribution map of the new genus.

Background/Objectives: The genus Tristerix comprises at least ten species, found from southern Chile to Colombia in South America. In Chile, several species of these hemiparasitic plants are known as quitral or quintral. Quitral, mainly T. corymbosus (syn. T. tetrandus), is used in alternative medicine for its anti-inflammatory, digestive, hemostatic, hypocholesterolemic, and wound-healing properties. This study investigates the phytochemical composition and antimicrobial properties of T. corymbosus. Methods: A hydroalcoholic extract of T. corymbosus was prepared from leaves and small branches. The addition of methanol, on the extract, produced precipitation allowing us to isolate a methanol-soluble fraction, a brown powder obtained after filtration, and a tar-like residue remaining in the flask. These fractions were resuspended and tested for antimicrobial activity. Results: All fractions showed activity against Streptococcus pyogenes, but not E. coli. The brown powder exhibits the strongest potency against Gram-positive bacteria, some Gram-negative and C. albicans. HPLC-MS analysis revealed presence of lipidic compounds with surfactant properties. Conclusions: The abundant lipidic molecules present in the analyzed fraction likely account for the antimicrobial effects through affecting membrane structure of microorganisms supporting the traditional wound-healing uses of T. corymbosus in ancestral medicine.

This article systematizes a research experience conducted in neighborhoods located in southern Chile, where plants emerge as relational agents mediating affects, memories, and territorial disputes. Through co-production of narratives, 4 stories were developed that reveal everyday ties with urban nature and the tensions imposed by neoliberal urbanization. Drawing from cuir theoretical frameworks, the study interprets psychic and collective fragmentations that foster practices of repair, plant-based care, and the recomposition of the body-territory. Additionally, a curatorial photomontage is created, articulating the embodied reflexivity of my research process. The article contributes by offering creative and situated methodologies that destabilize hegemonic modes of articulating and producing context-anchored knowledge, making visible mestizo memories, colonial wounds, and multispecies alliances as foundations for imagining cuir ecologies rooted in territory.

ABSTRACT Freshwater is essential for sustaining ecosystems and economic activities, and water quality largely determines its potential uses. Among water quality parameters, turbidity is particularly important due to its direct influence on aquatic ecosystem health, water resource management, and human well-being. This study investigates the long-term water quality and quantity dynamics of Lake Chapo, southern Chile, with the aim of assessing its evolution over the past 20 years. Thirteen machine learning models were evaluated to estimate turbidity under three scenarios: (1) using in situ limnological variables, (2) using meteorological variables, and (3) using the combined dataset. Overall, all models exhibited strong predictive performance. The best results were obtained with the multilayer perceptron model (R² = 0.78, MAE = 0.69, RMSE = 0.95), the Gaussian process model (R² = 0.75, RMSE = 0.78, MAE = 0.97 across all cases), and the random forest model (R² = 0.75, RMSE = 0.81, MAE = 0.96 in Case 1). Correlation analyses revealed that precipitation and wind speed exert the strongest meteorological influence on turbidity variability. These findings demonstrate that combining machine learning techniques with environmental data enhances understanding of aquatic ecosystem dynamics and supports improved freshwater resource management.

In Latin America, organizations, movements, and alliances led by Indigenous, peasant, afro-descendant, and mestizo women are particularly important in resisting extractivist activities as well as in coproducing concepts, methods, and praxis that invite us to do politics otherwise. Building on our work with/within the Asamblea de Mujeres Insulares por las Aguas (AMIPA) – a women's organization in defense of waters in the Chiloé archipelago (southern Chile) – we examine the resistance to energy-related conflicts by engaging with and expanding the Riverhood framework from a situated feminist perspective. Particularly, we will examine how the Riverhood framework (and its four ontologies/dimensions) relate, take different forms, and extend when considering AMIPA and allies’ recent turn to defend the Mawida Piwchen (Cordillera del Piuchén). We explore how this ‘new wave’ of (green) extractivism, focused on the Cordillera, represents a broader political-ontological struggle over waters and territories, from which the Piwchen – a multifaceted aqueous/territorial (more-than-human) being – is entering into politics. We highlight the role of women as key political articulators across organizations when analyzing how multiple ways of worlding – such as scientific knowledges, Indigenous cosmologies, and diverse feminisms – connect at the confluence of multiple (energy, land, and water) struggles. We argue that these connections not only express ‘epistemic interfaces’ but are also embodied-territorial intra/interconnections with multiple water bodies and watery beings. We suggest that these (feminist situated) articulations facilitated by AMIPA and allies offer a grounded and expansive expression of the ontology of “rivers-as-territories” and materialize other Riverhood ontologies, particularly when Chiloé's hydrosocial territory is re-imagined through hydro(geo-eco)-logic, hydro-cosmological, and (as we suggest) ‘hydrocorporeal’ dimensions. As a grounded contribution to the Riverhood framework, we conceptualize this comprehensive ontology as ‘Waters-as-Territories’ (both in capital letters and plural terms), which offer alternative ways of living, relating, and being with plural/territorialized waters.

Shifts in prokaryotic communities and giant sulphur-oxidising bacteria in response to salmon aquaculture in sub-Antarctic marine sediments.

Birth, life and death of the Devonian Chaitenia back-arc along the Southwestern Gondwanan margin (southern Chile)

Evaluation of bacterial membrane lipids (3-hydroxy fatty acids and branched GDGTs) as environmental proxies in lakes of the French Alps and southern Chile

Discovery of a suspected intrusion-related polymetallic Mo-Bi-Te-Au vein-stockwork system in the southern Chilean Andes: The Trapananda prospect, Patagonia, Chile

Flax (Linum usitatissimun L) is a versatile crop valued for its oil and functional compounds However, the presence ofphytotoxic aluminum (Al3+) in acid soil, limits its productivity, specifically in southern Chile where acid soils of the Andisoltype abound. The objective of this study was to characterize the genetic structure of 40 flax accessions using 2,200 singlenucleotide polymorphism (SNP) markers using STRUCTURE and Neighbor Joining (NJ) algorithms, and to analyze theirshoot and root phenotypic responses to aluminum toxicity in an acid soil to identify tolerant genotypes that could be usedin flax breeding. STRUCTURE and NJ methods grouped the 40 genotypes into three groups. Significant treatment andgenotypic effects were observed for total root length (TRL), root area (RA), apical root length (ARL) and root volume (RV)(p < 0.05). STRUCTURE groups 1 and 2 (G1 and G2) outperformed group 3 (G3) for RA (control and Al3+), ARL (Al3+), TRL(control), RV (control and Al3+), and relative root area. Fisher exact test for root traits under control and Al conditions enabledthe identification of genotypes differentially responding to stress and non-stress treatments. Pearson correlation analysisindicated that root traits either under Al3+ stress or limed soil conditions exhibited moderate to high associations amongthem (r= 032 – 096), suggesting shared root development regulation. Hierarchical and multivariate analyses of root traits andtheir relative growth indices identified the Al3+ tolerant genotypes G188 (fiber type), G87 (fiber type), and G401 (oil type),which showed superior relative total root length (RTRL), relative apical root length (RARL), and relative root area (RRA). Thepresent study revealed unexplored genetic variation in response to Al3+ stress and provide potential parental lines to improveflax adaptation to acidic soil conditions as those prevailing in southern Chile.

ABSTRACTObjective.Analyze the impact of the COVID-19 pandemic on influenza vaccination coverage in some countries in the Americas.Methods.This descriptive ecological study included Argentina, Chile, and Uruguay and analyzed information on influenza vaccination coverage in the countries during 2018–2023. The study reports annual estimates of influenza vaccination coverage expressed as a percentage of the population. The sources used were those reported by the Pan American Health Organization/World Health Organization and the ministries of health of the countries studied.Results.Comparatively, vaccination coverage rates according to risk groups among Argentina, Chile, and Uruguay show a downward trend without reaching optimal vaccination coverage for 2018 to 2023. Increased vaccination rates were reported in 2020 for all age and risk groups, except in Uruguay for children under 5 years of age. Among pregnant women, Argentina reported higher coverage in 2020 with 77%, Chile 90% (2018), and Uruguay 55% (2020). Among health workers, all three countries reached their highest coverage in 2020 (100%) but reported a decrease for 2022.Conclusion.The studied countries have observed a decrease in post-COVID-19 influenza vaccination coverage. Therefore, they are working to achieve optimal coverage, not only in influenza risk groups but across the entire population. Data on influenza vaccination coverage are limited in some cases. The availability of new vaccines can provide greater immunogenicity, efficacy, and effectiveness. However, they represent a challenge for the Expanded Program on Immunization, which requires cost-effectiveness studies to evaluate new vaccines while experiencing restricted national budgets.

This article studies air quality in some of the most polluted medium-sized cities in Central and Southern Chile, which have experienced high levels of coarse and fine particulate matter pollution in recent years. Since air quality is much better in spring and summer, the study focused on the winter period (from April 1 to August 31) and between 2018 and 2023, corresponding to the pre- and post-COVID-19 pandemic. We analyzed the effect of the COVID-19 lockdown on air quality in ten urban areas declared saturated by air pollution. Elsewhere in the world, and during the same period, air quality improved due to a recession or decrease in human activity. This was due to the quarantine imposed on the global population when the WHO declared the SARS-CoV-2 pandemic. However, this study detected a possible increase in environmental pollution between 2020 and 2022 in all the cities studied. The possible causes of this phenomenon are investigated. Finally, it was observed that the population was exposed to poor air quality throughout the study period in the different cities studied, which could have had very detrimental effects on the population's health.

Abstract This communication analyzes the distribution of benthic foraminifera in the infralittoral zone of northern Chile located between 26° and 29°S at depths between 7 and 12 m. Twenty-six taxa have been identified, whose density is mainly conditioned by grain size and hydrodynamics of the environment. A comparison with other coastal sectors of the Pacific coast of South America allows us to identify the most representative species of this area from southern Chile to Colombia. The results obtained are very interesting for their possible application in the reconstruction of Holocene paleoenvironments in the Atacama Desert.

Konün Wenu Hill (38°46′ S, 72°38′ W) is a prominent insular hill of considerable historical and cultural significance, located in the Mediterranean–temperate transition of south-central Chile. It hosts a ca. 10 ha remnant of native vegetation embedded within a matrix of grasslands and Pinus radiata D. Don (Pinaceae) plantations. Through a habitat-stratified floristic inventory covering the forest interior and adjacent habitats, we recorded 158 vascular plant taxa (Tracheophyta), comprising 90 native species (including 26 Chilean endemics) and 68 alien species. The forest remnant itself contained 62 native and 17 alien species. According to national conservation assessments, the flora includes two Vulnerable species—Asplenium trilobum Cav. (Aspleniaceae) and Citronella mucronata (Ruiz & Pav.) D. Don (Cardiopteridaceae)—and one Near Threatened species, Gardoquia multiflora (Phil.) Kuntze (Lamiaceae). The richest families were Asteraceae (24 spp.), Poaceae (14), Fabaceae (11), and Rosaceae (10). Canopy species such as Cryptocarya alba (Lauraceae), typical of Mediterranean sclerophyllous forests, Nothofagus obliqua (Mirb.) Oerst. (Nothofagaceae), characteristic of south-central deciduous forests, and Eucryphia cordifolia Cav. (Cunoniaceae), a temperate evergreen element from southern Chile, co-occur in the fragment and reflect the site’s transitional biogeographic character. The surrounding grasslands contributed a suite of heliophilous elements, notably Chloraea Lindl. spp. (Orchidaceae). Isolated trees scattered throughout the grassland mosaic served as distinct microsites compared to the surrounding open areas, facilitating the establishment of species more typical of forest or shrubland environments—such as taxa associated with closed-canopy forest (e.g., Francoa appendiculata Cav.) or sclerophyllous shrubland (e.g., Myrceugenia obtusa (DC.) O. Berg). Hierarchical clustering with SIMPROF (10,000 permutations, α = 0.05) showed that local road and forestry plantation each harboured floristic compositions statistically distinct from forest, edge, and grassland—and from one another—while these latter three habitats did not differ significantly among themselves. Despite its small size and isolation, Konün Wenu supports a substantial proportion of regional plant species richness and harbours taxa of conservation concern, underscoring the ecological value of both the remnant and the microhabitat network sustained by isolated trees across the surrounding matrix.

The temperate rainforests of southern Chile host a rich diversity of plants traditionally used in medicine, yet their bioactive potential remains underexplored. This study evaluated the chemical composition, antioxidant capacity, antibacterial activity, and cell viability of ethanolic leaf extracts from Cissus striata (CS), Mitraria coccinea (MC), and Raukaua laetevirens (RL), compared with Buddleja globosa (BG), a well-known medicinal shrub. Extracts were obtained using 70% ethanol, ensuring high recovery of polyphenolic compounds while avoiding thermal degradation. The total phenolic content (TPC) was highest in CS, exceeding values reported for green tea, while MC exhibited the greatest total flavonoid content (TFC). HPLC–MS/MS analysis showed that RL was rich in rutin, while CS exhibited a higher quercetin content. Antioxidant activity assessed through ABTS, DPPH, and FRAP assays, was correlated with polyphenolic composition. CS showed the highest antioxidant potential, surpassing green tea by ~39%, as determined via FRAP, while MC and RL displayed capacities comparable to BG. Antibacterial activity assays demonstrated that MC inhibited Escherichia coli with a minimum inhibitory concentration (MIC) of 12.5 mg/mL, lower than that of ampicillin, whereas CS was highly active against Staphylococcus aureus, with an MIC of 0.39 mg/mL, equivalent to the activity exhibited by tetracycline. Cytotoxicity assays confirmed that the extracts did not reduce human cell viability, supporting the potential of Chilean native shrubs as safe, natural sources of antioxidants and antimicrobials for food and pharmaceutical applications.

Several solutions are being explored to reduce methane intensity in dairy farms, but there is no consensus for commercial pastoral dairy systems in temperate zones. We evaluated the effects of essential oils (EO) supplementation on CH4 intensity and performance in dairy cows within a commercial pasture-based system in southern Chile. Thirty multiparous cows were randomly assigned to a control group and a treated group, with a general average yield of 22.3 ± 5.37 kg/d and an average parity of 3.42 ± 1.13. The treated group received concentrate supplemented with a mixture of EOs. Enteric CH4 emissions were measured using GreenFeed®. Milk yield (kg/d), composition (% fat, % protein, urea, somatic cells), plasma biochemistry, and grassland proximal analysis (NIRs) were also evaluated. Results showed a significant increase in fat-corrected milk production (4.6 kg) in the treated group during the first trial period where the grassland was highly nutritious, offering 19.8% crude protein as well as a pool of long-chain fatty acids. Additionally, CH4 intensity was significantly lower in the treated group (1.3 gCH4/ECM) during the first phase. EO supplementation strategies represent a suitable non-invasive intervention suitable for commercial grassland-based systems in southern Chile that is strongly influenced by pasture quality.