Coquimbo Region Research Articles

Increases in the Amounts of Agricultural Surfaces and Their Impact on the Sustainability of Groundwater Resources in North-Central Chile

Water is a fundamental resource for Chile’s productive structure, which is more important in arid areas, and especially with agricultural uses. This study was based on two basins (Cogotí and Illapel) located in the Coquimbo Region of north-central Chile. In this region, surface water rights were closed in 2002 and the only current option is the use of groundwater. These basins have high water demands due to the use of surface and groundwater for agricultural purposes, a fact that should influence the sustainability of groundwater reserves over time. The objective of this study was to determine how much agricultural use has affected the availability of groundwater in two basins. Under the previous context, the evolution of agricultural irrigation surfaces was evaluated using Landsat images and forest classifications. Similarly, groundwater reserves were evaluated using the recessive curves of hydrographs associated with the beginning of each hydrological year. The results show an increase in the agricultural area between 1996 and 2016, with a subsequent decrease, while groundwater reserves denoted significant decreases over time. In conclusion, a significant decrease in the volumes of groundwater reserves in both basins was observed, a decrease that is consistent with the increase in irrigated areas.

Natural History of the Genus Elasmoderus Saussure, 1888 (Orthoptera: Tristiridae), an Endemic and Eremic Element of the Transitional Coastal Desert of Chile.

The genus Elasmoderus belongs to the family Tristiridae, an orthopteran group that is distributed across the transitional region of South America and represented in the Andean areas of Peru, Argentina, and Chile. The species of Elasmoderus have morphological adaptations that make them especially suited for surviving in extreme arid environments and are an endemic and eremic group of the north-central region of Chile. On the basis of field samplings, direct observations, and a comprehensive literature review, we collected information about the genus Elasmoderus. The objectives of this research were: (i) to provide updated information on the geographical distribution range of the species of the genus Elasmoderus, and (ii) to collect and synthesize the most relevant information on the natural history and ecology of this orthopteran group as a basis for future long-term studies of its populations. Although this genus is underrepresented compared to other orthopteran families, it has developed interesting adaptations to extreme arid environments that remain unstudied to this date. E. lutescens is known to be one of the species with a wider latitudinal distribution, mostly on the coast and longitudinal valley of Atacama. E. minutus has a more restricted distribution, whereas E. wagenknechti is concentrated in coastal and interior environments of the Coquimbo region, an area where it reaches high population densities, thus affecting crops and natural vegetation and polluting water sources. Our findings underscore the importance of conducting comprehensive research on native insect groups that are poorly known but crucial for arid and semiarid ecosystems. These data will serve as a starting point for conducting long-term studies on this orthopteran group to gain a better understanding of the importance and role of these species in the semiarid ecosystems of northern Chile.

The effect of a collective competence intervention on collective efficacy, psychological wellbeing, and social wellbeing: a quasi-experimental study of a sample of healthcare workers during the COVID-19 crisis.

The health crisis associated with COVID-19 led to a period of increased demand on the operational and social organization of healthcare centers, which often had a negative impact on the psychological and social wellbeing of healthcare workers. In order to tackle this issue, an intervention plan was designed to develop collective competences through various participatory strategies. This study sought to determine the effect of this intervention on the variables collective efficacy, psychological wellbeing, and social wellbeing in healthcare workers by performing a pretest and posttest comparison with a control group. The variables were evaluated using a non-probability, purposive sample of 80 healthcare workers from three Family Healthcare Centers (CESFAM) located in the Coquimbo Region, Chile, within health crisis context. The intervention group was composed of voluntary participants, while the control group only completed the evaluations. The intervention consisted in 6 training workshops focused on improving collective management, group synergy, collaborative problem-solving, communicative strategies, and overall team care. The analysis shows that the collective competence intervention had a positive effect on the collective efficacy, psychological wellbeing, and social wellbeing of the participating healthcare workers during the COVID-19 crisis. Only specific factors of these variables did not undergo a significant impact. The results of this study suggest that interventions aimed at improving collective organizational competences, apart from increasing collective efficacy, can have a positive impact on healthcare workers' psychological and social wellbeing in a context of occupational adversity.

Orthotrichumcamanchacanum, a remarkable new moss species from Chile (Bryopsida, Orthotrichaceae).

Orthotrichumcamanchacanum is presented as a newly described species from Chile. The species is primarily distinguished by its emergent capsule with cryptoporous stomata, a double peristome, linear-lanceolate stem leaves with a long hyaline aristae in apex, conspicuously differentiated perichaetial leaves, and a densely hairy vaginula. The species was discovered in the mountain massif of the Andes in the Coquimbo region, notable for its unique climatic conditions. Molecular data and a brief discussion comparing the newly described species with the most closely related taxa are also provided.

Reconstruction of extreme floods and tsunamis from coastal sedimentary archives in Los Choros, Coquimbo region, 28°S, Chile

Reconstruction of extreme floods and tsunamis from coastal sedimentary archives in Los Choros, Coquimbo region, 28°S, Chile

Characterization of Seismicity and Seismic Hazard in the Coquimbo Region, Chile: A Probabilistic Study

Characterization of Seismicity and Seismic Hazard in the Coquimbo Region, Chile: A Probabilistic Study

A multi-objective optimization model for planning emergency shelters after a tsunami

Vertical evacuation helps people escape tsunami risks by elevating them above the level of tsunami inundation, usually by moving to higher ground or taking refuge in tall buildings or other elevated structures. Unlike horizontal evacuation, which involves moving away from the coast to higher ground, vertical evacuation reduces the demand for horizontal evacuation routes that can become congested and impede evacuation efforts. Therefore, investing in critical infrastructure that enables vertical evacuation is crucial in tsunami-prone areas. This study proposes a multi-objective optimization model to help decision-makers assign critical infrastructure for vertical evacuation in tsunami-prone areas. Critical infrastructure includes buildings that can provide shelter during a tsunami and road networks for rapid access to shelter points. The proposed model balances three objectives: (1) minimizing investment costs in critical infrastructure, (2) maximizing the population covered by shelters, and (3) minimizing the evacuation time for evacuees to reach the shelters. This model is tested on real-world data from the Coquimbo-La Serena coastal conurbation in the Coquimbo region of Chile. The study contributes to the literature on tsunami evacuation modeling and provides valuable information for decision-makers to plan and invest in critical infrastructure for vertical evacuation during tsunamis. A sensitivity analysis of various parameters is conducted, and managerial insights are provided.

Characterization of suicidal behavior in Coquimbo, Chile, between 2018 and 2020.

Suicidal behavior is a public health problem worldwide. The World Health Organization estimated 700 000 deaths for the year 2021. This study aimed to estimate the prevalence of suicidal behavior and describe its related factors in the Coquimbo Region, Chile, between 2018 and 2020. 2190 suicide attempt notifications from the regional epidemiological surveillance system were analyzed, corresponding to 1781 people, along with 217 reports from the Forensic Medical Service of people who died by suicide. The overall suicide rate for the region during that period was 9.79 deaths per 100 000 inhabitants. The 2018 rates were standardized according to available information, with direct methods for the regional rate (9.55 per 100 000 inhabitants) and indirect methods for the communes. Rural communes presented higher rates than urban ones. Women showed a higher risk of attempts (OR 1.28; 95% CI 1.23 to 1.33) and a lower risk of suicide compared to men (0.086; 0.06 to 0.13). Young people had a higher risk of suicide attempts and a lower risk of suicide compared to older people. The increased suicide rates in older people (70 to 79 years) during 2020 are noteworthy. Basic education level is a risk variable for suicide (2.21; from 1.15 to 4.23), compared to having higher education. Previous suicide attempts and psychiatric pathology are risk factors. Suicide prevalence and related factors are similar to those reported in other studies and national reports, highlighting rurality and higher risk in older male adults. In contrast to suicides, attempts are more frequent in women and young people. A history of mental health problems, previous attempts, and family violence are risk factors for both outcomes. Knowing the patterns of suicidal behavior in the population is fundamental for its prevention.

Development and assessment of a vulnerability index for access to rural drinking water and sanitation services in the semi-arid region of north–central Chile

Abstract The present study aimed to develop and assess a vulnerability index for access to rural drinking water and sanitation services, which was applied to 42 Rural Sanitation Services in the Coquimbo Region, Chile. For the development and assessment of the vulnerability index, the construction of composite indicator methodology was employed. An underlying model based on 65 indicators, linked to nine sub-pillars and three pillars, was established. In addition, the COINTool software was used for the development and analysis of the composite indicator results. The vulnerability index results showed medium vulnerability at regional and provincial levels, with a greater degree of vulnerability at a commune level. At a Rural Sanitation Services level, 2.4% of the evaluated services presented high vulnerability, 73.8% presented medium vulnerability, and 23.8% presented low vulnerability. The vulnerability index values obtained for the Rural Sanitation Services fluctuated from a minimum value of 32.3% to a maximum value of 64.1%. The significance of the vulnerability indicator developed and assessed lies in its high potential as a tool and/or methodology to monitoring, from a multidimensional perspective, the effectiveness of policies, strategies, and/or actions implemented at the level of Rural Sanitation Services, contributing to strengthened decision-making in vulnerability reduction.

Occurrence of Pseudomonas cichorii Causing Midrib Rot of Lettuce Under Hydroponic Cultivation in Chile

In Chile, lettuce is the vegetable that has increased in cultivated area the most in recent years, reaching 8,309 ha. The Coquimbo Region contributes the most to this growth in production with 3,284 ha in 2022 (ODEPA 2023). Most lettuce is grown under open field conditions, but there is significant production in greenhouses and an increase in hydroponic production systems (INIA 2017). During April to June 2021 and 2022 in the Coquimbo Region, butterhead-type lettuce seedlings (Lactuca sativa) cv. Neil, cultivated under a hydroponic system, showed severe brown to black lesions in the leaves and midrib (Figure S1). To determine the etiology of this problem, samples of diseased plants were taken. Pieces of symptomatic tissue were macerated, and the extract was spread on nutrient agar (NA) and on King's B medium (KB) and incubated at 23°C for 48 h. The bacterial colonies observed were predominantly circular, creamy-white in color with irregular margins and fluorescent in KB medium. Isolates were gram-negative strictly aerobic. LOPAT test (Lelliot et al. 1966) results of two selected isolates were: levan production (-), oxidase reaction (+), potato soft rot (-), arginine dihydrolase production (-), and tobacco hypersensitivity (+), which corresponds to the profile of Pseudomonas cichorii. Molecular identification was performed through amplification and sequencing of the 16S rRNA (GenBank Accessions No. OR540674 to OR540675), gyrB and rpoD genes (Hwang et al. 2005; Sarkar and Guttmann 2004) (GenBank Accessions No. OR558279 to OR558282). BLAST analysis of the 16S rRNA gene of the isolates resulted in a match with a 99.86% identity with P. cichorii type strain ATCC 10857 (NR_112070.1). BLAST analysis of gyrB and rpoD resulted in a match with a 100% (630/630 bp) and >99% (546/550 bp) identity respectively, with strains of P. cichorii. Five six-month-old lettuce plants cv. Desert Storm were pricked in the midrib with a toothpick smeared with a fresh colony grown on KB medium. Seven days after inoculation, the plants showed dark brown, watery lesions, characteristic of damage caused by P. cichorii (Figure S1). Bacteria were isolated again from the inoculated plants and were identified as P. cichorii using LOPAT and molecular identification techniques. Midrib rot caused by P. cichorii was reported as an emerging disease of greenhouse-grown lettuce by Cottyn et al. (2009). In Chile, P. cichorii was previously described affecting nectarine fruits (Pinto de Torres and Carreño Ibañez 1983) and reported as a pathogen of lettuce among others horticultural crops by Servicio Agrícola y Ganadero of the Government of Chile (Acuña 2008), but this is the first report of P. cichorii affecting hydroponic lettuce plants in Chile. These results will be the basis of future studies to evaluate the origin of the infection, the potential dissemination, and the implementation of disease management to avoid the damage caused by this bacterium in hydroponic systems in this crop of growing importance in Chile.

First Report of Pantoea ananatis and Pantoea eucalypti causing onion leaf blight and bulb decay in Central Chile.

Nearly 5,400 hectares of long-day onions (Allium cepa) are cultivated in the Central Zone of Chile (UTM 33°3´S to 37°24´S). During summer 2021-22 and 2022-23 (December to February), followed by high temperatures (around 35°C) and high humidity conditions, symptoms showing yellowing, soft rot, blight on old leaves, necrotic tips, and soft bulbs were observed. The affected plants were observed in "spots" into the fields, and the incidence reached 5-10%. The severity was high, and 70-80% of the affected plants died. Symptomatic plants from different fields from the Coquimbo, Metropolitan, O´Higgins and Maule regions were sampled. Isolations were made using casamino-acid peptone glucose (CPG) agar medium (Schaad, 2001). Yellow-pigmented, circular to irregular shaped colonies were observed. Molecular identification was carried out by partial 16S rRNA gene sequencing, resulting in the identification of 18 isolates of Pantoea spp. from twelve different fields. Selected strains were biochemically analyzed using the GEN III BIOLOG microtest system (Hayward, CA) and were identified as Pantoea spp. BLAST analyses of the 16S rRNA sequences (602 nt) of selected strains (GenBank Accession No. OR527817 to OR527819) against the NCBI Database resulted in the identification of Pantoea species with 100% coverage and 100% identity. To determine the Pantoea species of each strain, housekeeping gene gyrB (Delétoile et al. 2009) was amplified and sequenced (GenBank Accessions No. OR544061 to OR544063). BLAST analysis (802 nt) of selected strains resulted in 100% coverage and 100% identity, identifying three different species: P. ananatis, P. eucalypti, and P. agglomerans. Pantoea species were isolated from both leaves and bulbs and no more than one species was observed per field. Pathogenicity assays in onion plants and bulbs were performed based on the methodology described by Asselin et al. (2018). Five onion plants cv. Cimarron of thirteen-week-old were inoculated by wounding an external leave with a sterile toothpick previously immersed in a bacterial suspension at ~ 108 CFU/mL and maintained at 26-28°C for 30 days in high humidity conditions. Control plants were inoculated with sterile water. Plants inoculated with Pantoea spp. showed chlorosis, soft rot, and necrosis mainly in older leaves, as observed in the field, while negative control plants remained healthy. Pantoea spp. were re-isolated from the inoculated onion plants. Toothpicks dipped in the inoculum were stuck 4 cm into the shoulders of onion bulbs and incubated at 26°C for 20 days. Water was inoculated as a negative control. At the end of the incubation period, the bulbs were opened longitudinally across their inoculation sites and shrunken, brownish, watery scales were observed. Pantoea species have been previously described as causing leaf blight of onions in Georgia and Michigan in the USA and South Africa, Brazil, and Uruguay (Hattingh and Walters 1981; Gitaitis and Gay 1997; Edens et al. 2006; Tho et al. 2015; De Armas et al. 2022; Rosende et al. 2022). P. agglomerans was recently reported in Chile (Sepúlveda et al. 2023), but this is the first report of P. ananatis and P. eucalypti affecting onions in central Chile. This detection is an alert call for the onion's growers and exporters in Chile for upcoming seasons, where conditions predisposing to disease may continue to occur. It is crucial to continue analyzing the factors that caused the appearance of this new disease in onions.

Toward a Spectrophotometric Characterization of the Chilean Night Sky. A First Quantitative Assessment of ALAN across the Coquimbo Region

Light pollution is recognized as a global issue that, like other forms of anthropogenic pollution, has a significant impact on ecosystems and adverse effects on living organisms. Plentiful evidence suggests that it has been increasing at an unprecedented rate at all spatial scales. Chile—which, thanks to its unique environmental conditions, has become one of the most prominent astronomical hubs of the world—seems to be no exception. In this paper we present the results of the first observing campaign aimed at quantifying the effects of artificial lights at night on the brightness and colors of the Chilean sky. Through the analysis of photometrically calibrated all-sky images captured at four representative sites with an increasing degree of anthropization, and the comparison with state-of-the-art numerical models, we show that significant levels of light pollution have already altered the appearance of the natural sky even in remote areas. Our observations reveal that the light pollution level recorded in a small town of the Coquimbo Region is comparable with that of Flagstaff, Arizona, a ten times larger Dark Sky city, and that a mid-size urban area that is a gateway to the Atacama Desert displays photometric indicators of night sky quality that are typical of the most densely populated regions of Europe. Our results suggest that there is still much to be done in Chile to keep light pollution under control and thus preserve the darkness of its night sky—a natural and cultural heritage that it is our responsibility to protect.

Enhancing employability through training programmes in Chile: A qualitative study of the challenges identified by local actors involved in a subnational experience

AbstractActive labour policies are globally adopted to tackle unemployment and enhance job matching. In Chile, a predominantly supply‐focused approach involves training workers, especially in vulnerable groups, as it is believed that investing in human capital will align job demand and available skills. This subnational Chilean case study in the Coquimbo region delves into the factors influencing worker training and placement programme implementation, with a specific focus on stakeholders' perceptions. Through qualitative data from interviews and focus groups, the research seeks to explore subjective challenges, including individual perspectives, governance and structural factors. Various variables affect policy implementation at different levels. On the micro level, actor motivations like personal goals and financial incentives are crucial for policy design. Regional governance levels grapple with coordination difficulties that impact programme implementation. Collaboration among stakeholders like government agencies, educational institutions and employers is essential. Structural issues within the regional economy and the target population also pose challenges to policy implementation. The study suggests that a comprehensive policy approach that considers the interconnectedness of institutions, labour markets, skills and the various stakeholders involved in the process is vital to address the complexity of active labour policies at the local level in Chile.

Insects associated to ephemeral pools in Huentelauquén (29ºS Coquimbo Region, Chile).

In northern central Chile, ephemeral pools constitute shallow isolated water bodies with a favourable habitat for fauna adapted to seasonal changes. Based on the limited knowledge about the fauna-particularly insects-associated to these ecosystems, the objective of this study was to characterize the richness, composition, structure and similarity of the insect communities associated with ephemeral pools in Huentelauquén (29º S, Coquimbo Region, Chile). By using pitfall traps, 10,762 individuals were captured, represented by 7 orders, 27 families, and 51 species. Coleoptera and Hymenoptera were the best represented orders, with Neuroptera, Orthoptera and Plecoptera being poorly represented groups. The non-parametric estimators evaluated showed wealth values above those observed for all the studied pools, and their accumulation curves suggest the existence of an incomplete species inventory in the studied community. Additionally, the hierarchical and ordering analysis showed groupings of pools located in the northwest and southeast of Huentelauquén. Preliminarily we found a negative correlation between the area of the pools and the richness (species) and abundance of insects. Additional studies (on other arthropod groups and other seasons of the year) could provide a better understanding of the local processes of extinction and colonization of the species inhabiting these fragile coastal environments.

Land use around influences the entomological community in lettuce horticultural systems.

The complexity of the agroecosystem can also be assessed by the different land uses in the system and the surroundings, being a relevant way to assess the heterogeneity of the landscape and the effects on the community of interest, in this case, entomofauna. Thus, the objective of this work is to verify how the use of soil in the surroundings of Chilean lettuce horticultural systems, in the Coquimbo Region, alters the entomological community of the crop. Insect sampling was conducted (February 2021 to March 2022) using yellow pan traps. Two sites will be sampled on each of the seven studied lettuce crops. Land use and land cover classes were defined: Forests, water bodies, shrub vegetation, grasslands, barren lands, impermeable surfaces, and urban areas. After land use and land cover classification, buffers of 500 to 5,000 m were created around each data collection point. For data analysis, the percentages of land use of different classes were compared with the ecological attributes: Abundance of insects, abundance of insect pests, richness of entomological families and types of oral apparatus (licker-sucker, mandible, picker-sucker, and sucker). Land uses at different distances from horticultural systems affected the entomological community.

Understanding and documenting decorated façades of the Coquimbo Region in Chile

The present contribution aims at documenting decorated earthen architecture in the Coquimbo Region of Chile, in the provinces of Limarì and Elqui, specifically in Tulahuèn and Pisco Elqui. The peculiarity of these decorated façades is their rich ornamental composition, resulting in interesting patterns and textural realizations. These decorated façades witness the significance of Chilean earthen heritage and thus deserve an in-depth investigation. The vernacular buildings observed in the Limarì Valley present irregular and non-formal geometric decorations and graphic representation, engraved motifs and tiling, and wavy patterns, creatively interpreting the façade as the owner's canvas. The earthen architecture of Pisco Elqui shows a formal façade decorative composition, which could be associated with the presence of a school of masters and artisans with decorative expertise. The latter façades present classical features and stuccoes combined with geometrically composed pattern textures and engraved elements. The vernacular decorations of Limarì buildings' façades enclose immaterial values and express themselves through the anonymous touch of the inhabitants, revealing intimate stories and ancient local memories. The present paper also promotes the possibility of reviving this decorative tradition as a tool for contemporary projects for the renovation of earthen houses at the urban scale, enhancing the importance of using local and sustainable materials.

Evaluation of the Levelized Cost of Energy With New Costs for Concentrating Solar Power Tower Plants in Northern Chile and Impact of Green Taxes

The world is undergoing an energy transformation, from a system based on fossil fuels to a system based on renewable energy, in order to reach the Paris Agreement target. Chile is no exception, and through the Asociación de Concentración Solar de Potencia (ACSP) has generated a new cost structure for tower-based Concentrated Solar Power (CSP) technology in the framework of the Long-Term Energy Plan, which updates the costs reported in previous studies. The changes experienced in this cost structure make it necessary to study the impact of this cost structure on the levelized cost of energy (LCOE). This work develops simulations of CSP tower plants analyzing their generation and the LCOE based on the new cost structure mentioned, for the north of Chile between the Arica and Parinacota region and the Coquimbo region. The most relevant results show a significant reduction in the LCOE, compared to studies from 2020, reaching a minimum LCOE value of 52,6 USD/MWh. On the other hand, the impact on the net social benefit of including the green tax to the merit order of each of the generating plants that make up the electric park until 2021 is studied, which yields a negative impact under current legislation.

Seed Characterization and Evaluation of Pre-Germinative Barriers in the Genus Alstroemeria (Alstroemeriaceae)

The genus Alstroemeria originates from South America, and Chile is one of the countries showing the highest number of taxa (49), of which 40 are endemic. However, anthropogenic and environmental factors are affecting the survival of these species; therefore, the conservation of their genetic variability is of great importance, and can be achieved through seed propagation. Seeds of this genus normally show dormancy, which prevents their germination under favorable conditions. The objective of this work was to understand the pre-germinative barriers to develop a seed propagation protocol for native alstroemerias and to determine the best method to break their dormancy. Seeds from 10 Alstroemeria species native to Chile were collected from the Coquimbo Region to Maule Region, and 5 pre-germination treatments combining scarification and stratification methods were evaluated. Moreover, a morphological and biochemical evaluation of the seeds was performed. The results showed a positive and significant effect on the percentage of emergence using seed soaking in water and cold stratification at 13 °C, obtaining the best results in A. pelegrina and A. angustifolia subsp. angustifolia (98.33% and 91.67%, respectively) after 30 days. The morphological characterization of seeds showed a wide range of size (diameter), from 2.18 mm (A. pulchra subsp. pulchra) up to 3.43 mm (A. pelegrina), and different shapes (pseudospherical and angular) and textures (rough and smooth). The highest phenol and tannin concentrations were observed in A. hookeri subsp. maculata with values of 4.71 and 30.95 mg g−1 of seeds, respectively. A bigger size of the seed and a higher concentration of phenols could be related to a higher % of emergence of alstroemeria seeds.

One Welfare: Assessing the Effects of Drought and the COVID-19 Pandemic on Farmers' Well-Being and Their Perception of Goats' Welfare.

Considering the interconnections between human well-being, animal welfare, and the environment, this study aimed to investigate the impacts of drought and the COVID-19 pandemic on small-scale goat farmers' well-being and their perception of goats' welfare following the One Welfare framework. Using a telephone survey, close-ended questions, and Likert scales, we assessed the impacts of drought and the COVID-19 pandemic on human well-being and animal welfare in the Coquimbo region of Chile. The DASS-21 questionnaire was used to evaluate farmers' mental health. Goat farmers perceived the scarcity of water and food for animals as factors that negatively affected animal productivity and welfare and caused an increase in farmers' stress levels. Farmers who had not been visited by a veterinarian showed higher levels of stress than those who received one visit during the year (M = 10 vs. 2, p = 0.025). Additionally, farmers who perceived better welfare of their animals showed lower levels of depression (rs = -0.17, p = 0.048), anxiety (rs = -0.21, p = 0.016), and stress (rs = -0.33, p < 0.001). These findings emphasize the importance of addressing farmers' mental health and veterinary support as crucial aspects to ensure both goat welfare and farm productivity.

Spatial distribution of two invasive freshwater snails and environmental correlates of the mollusc community abundance, a case study in Chile

Invasive species can produce negative effects on native species. We studied the densities of Physa acuta and Potamopyrgus antipodarum, two invasive freshwater snails in Chile, and analyzed the relationship between environmental parameters and the relative abundances of the mollusc community in several ecosystems. Densities of both species were studied in three habitat types (stones, smooth sediment, and vegetation) in the Consuelo Stream, Coquimbo Region. Densities of Potamopyrgus antipodarum were significantly higher on stones, while Physa acuta showed no significant differences between habitats. A canonical correspondence analysis (CCA) demonstrated that both Physa acuta and Potamopyrgus antipodarum were related to oxidation-reduction potential but not to salinity. The results also showed that native mollusc fauna is sparsely represented in the study area, possibly due to the presence of these invaders, although drought, water pollution, and other unstudied anthropogenic factors may also be involved.