Altered Environment Research Articles

Rowing Against the Tide: The Golden Mussel (Limnoperna fortunei) Leaves DNA Footprints Along Its Invasion Route in South American Rivers

The invasion of the golden mussel has resulted in considerable environmental and socioeconomic alterations, which present a considerable threat to the native biodiversity and sustainability of the region. Understanding the distribution and biological characteristics of this Asian mussel, as well as its interaction with human activities, is of the utmost importance to developing effective strategies for mitigating and preventing its further spread. This study examines the dispersal route and incidence of golden mussels, tracing their movement from initial populations in Argentina to their arrival in the São Francisco River Basin (SFR). The presence of the mussel was confirmed through an integrative assessment that included shell taxonomic analyses and mitochondrial DNA signatures. This assessment identified populations located 7.5 km from the river’s mouth, close to the Atlantic Ocean, in areas such as shrimp farms, artisanal ports, and marinas. The analysis of mitochondrial DNA revealed the presence of South-American-specific and shared ancestral haplotypes in the SFR, Grande River, and Argentina. These findings indicate that intracontinental colonization toward the northeast region of South America originated from Asian populations that entered South America via Argentina. The absence of Asian-specific signatures in the SFR, combined with a geomorphological structure unsuitable for large ports or transoceanic vessels, supports the hypothesis of the intracontinental dispersal of Limnoperna fortunei.

Genotoxic damage in green turtles (Chelonia mydas) exhibits regional and annual fluctuations

Tourism, urban development, and sargasso beaching caused environmental alterations in the Mexican Caribbean coasts. Little ecotoxicological information exists on the green turtle (Chelonia mydas) population inhabiting this region. Micronucleus (MN) and erythrocytic nuclear abnormalities (ENA) tests are non-destructive DNA damage biomarkers. We aimed to determine local (Punta Arenas, Akumal, Punta Herrero, and Xcalak) and annual (2015–2019) variability in MN/ENA frequency to understand genotoxic damage extent. Almost all the individuals sampled (n = 166) presented DNA damage (98.8%); the lack of correlations between MN/ENA and biological variables confirmed the usefulness of these tests as biomarkers. The southern foraging site had the highest number of MN/ENA; an increase over time was found in the most urbanized and the most protected sites, coinciding with previously reported regional variability of persistent organic compounds, heavy metals, and annual massive influx of sargasso. Considering the sentinel status of green turtles, the advantages of the blood tests, and the continuous accelerated urban development in the Caribbean, long-term monitoring of this species is advised.

TIMP1 regulates ferroptosis in osteoblasts by inhibiting TFRC ubiquitination: an in vitro and in vivo study

BackgroundIn clinical practice, alterations in the internal environment of type 2 diabetes can significantly affect bone quality. While the increased risk of fractures among diabetic patients is well-established, the precise mechanisms by which hyperglycemia influences bone quality remain largely unclear.MethodsWestern blotting, immunohistochemistry (IHC), and micro-CT were used to examine ferroptosis-related protein expression and bone morphology changes in the bone tissues of type 2 diabetic mice. The CCK8 assay determined the optimal conditions for inducing ferroptosis in osteoblasts by high glucose and high fat (HGHF). Ferroptosis phenotypes in osteoblasts were analyzed using flow cytometry, Western blotting, and two-photon laser confocal microscopy. Transcriptomic sequencing of the control and HGHF groups, followed by bioinformatic analysis, identified and validated key genes. TIMP1 was knocked down in osteoblasts to assess its impact on ferroptosis, while TFRC expression was inhibited and activated to verify the role of TIMP1 in regulating ferroptosis through TFRC. The therapeutic effect of TIMP1 inhibition on osteoporosis was evaluated in a type 2 diabetic mouse model.ResultsThe expression of TIMP1 is increased in type 2 diabetic osteoporosis. In vitro, TIMP1 knockout inhibited ferroptosis in osteoblasts induced by high glucose and high fat (HGHF). However, overexpression of TFRC reversed the ferroptosis inhibition caused by TIMP1 knockout. Suppression of TIMP1 expression alleviated the progression of osteoporosis in type 2 diabetic mice. Mechanistic studies suggest that TIMP1 regulates HGHF-induced ferroptosis in osteoblasts through TFRC.ConclusionThis study demonstrates that TIMP1 expression is increased during type 2 diabetic osteoporosis and that TIMP1 promotes ferroptosis in osteoblasts by regulating TFRC. These findings suggest that TIMP1 is a promising novel therapeutic target for type 2 diabetic osteoporosis.

Far-Red Light Inhibits Soybean Biomass and Yield by Modulating Plant Photosynthesis

Alterations in the light environment can significantly influence soybean morphology and yield formation; however, the effects and mechanisms of different light qualities on these aspects require further investigation. Consequently, we selected soybean cultivars with marked differences in light sensitivity as test materials, conducted experiments with red, blue, and green light qualities against a blue light background, and analyzed parameters related to leaf photosynthetic capacity, chlorophyll fluorescence, morphological characteristics, biomass, and yield variations following different light quality treatments. The results showed that following far-red light treatment, soybean plants exhibited significant shade avoidance syndrome, internode elongation, increased plant height, and a marked reduction in both root and leaf biomass, as well as total biomass. Furthermore, there was a substantial reduction in photosynthetic capacity. This indicated that far-red light exerts an inhibitory effect on soybean growth and yield formation. Red light has basically no regulatory effect on plant morphology and yield, while green light has a yield-increasing effect, but there was a cultivar effect. This study not only enhances our understanding of the mechanisms through which light quality regulates plant photosynthesis but also lays a scientific foundation for future crop light environment management and for the further exploration of light quality’s regulatory potential on crop growth.

Harnessing the microbiome: probiotics, antibiotics and their role in canine and feline gastrointestinal disease.

Unfavourable alterations of the host microbial environment, known as dysbiosis, have been identified in many canine and feline gastrointestinal (GI) diseases. As a result, normalisation of microbial composition and function has become an important therapeutic target. Given the complex and individualistic interplay between the resident microbiota, host and environment, a multimodal approach is often necessary when addressing dysbiosis in dogs and cats with GI disease. Systemic antibiotics are often empirically used to treat acute and chronic GI diseases. However, with modern genomic techniques demonstrating the profound negative effect antibiotics can have on the GI microbiota and the rapid emergence of resistant bacteria globally, there has been an increased focus on identifying antibiotic alternatives for use in small animal practice. Biotics, such as prebiotics, probiotics and synbiotics, are of growing interest due to their potential supportive effect on the microbiota. This article reviews the evidence for the use of biotics in canine and feline GI disease, highlighting how judicious use of antibiotics and targeted probiotic supplementation can enhance patient outcomes by promoting a balanced gut microbial environment.

Environmental Stress-Induced Alterations in Embryo Developmental Morphokinetics.

The association between embryo morphokinetics and its developmental competence is well documented. For instance, early cleaved embryos are more competent in developing to blastocysts, whereas the proportion of abnormally cleaved embryos that further developed to blastocysts is low. Numerous factors, such as the parental age, lifestyle, health, and smoking habits have been reported to affect the embryo morphokinetics and, consequently, its development. However, less is known about the effect of environmental stressors on embryo morphokinetics. The current review discusses the effect of the most concerning environmental stressors on embryo morphokinetics. These stresses include heat stress and human-made chemicals such as phthalates (e.g., bis-(2-ethylhexyl phthalate, dibutyl phthalate, dimethyl phthalate, and their primary metabolites), herbicides (e.g., diaminochlorotriazine, the primary metabolite of atrazine), pharmaceutical compounds (e.g., carbamazepine, nocodazole) and pro-oxidant agents (cumene hydroperoxide, Triton X-100), as well as naturally occurring toxins such as mycotoxin (e.g., aflatoxin B1 and its metabolite, and ochratoxin A). In addition, this review discusses the effect of ionizing or non-ionizing radiation and viral infections (e.g., SARS-CoV-2, papillomavirus). Finally, it points out some potential mechanisms that underlie the impairment of embryo morphokinetics, and it suggests protective compounds, mainly the supplementation of antioxidants to improve the morphokinetics, and consequently, the embryo developmental competence.

Diversity and ecology of microbial sulfur metabolism.

Sulfur plays a pivotal role in interactions within the atmosphere, lithosphere, pedosphere, hydrosphere and biosphere, and the functioning of living organisms. In the Earth's crust, mantle, and atmosphere, sulfur undergoes geochemical transformations due to natural and anthropogenic factors. In the biosphere, sulfur participates in the formation of amino acids, proteins, coenzymes and vitamins. Microorganisms in the biosphere are crucial for cycling sulfur compounds through oxidation, reduction and disproportionation reactions, facilitating their bioassimilation and energy generation. Microbial sulfur metabolism is abundant in both aerobic and anaerobic environments and is interconnected with biogeochemical cycles of important elements such as carbon, nitrogen and iron. Through metabolism, competition or cooperation, microorganisms metabolizing sulfur can drive the consumption of organic carbon, loss of fixed nitrogen and production of climate-active gases. Given the increasing significance of sulfur metabolism in environmental alteration and the intricate involvement of microorganisms in sulfur dynamics, a timely re-evaluation of the sulfur cycle is imperative. This Review explores our understanding of microbial sulfur metabolism, primarily focusing on the transformations of inorganic sulfur. We comprehensively overview the sulfur cycle in the face of rapidly changing ecosystems on Earth, highlighting the importance of microbially-mediated sulfur transformation reactions across different environments, ecosystems and microbiomes.

Burnout Levels of Healthcare Professionals During the Covid-19 Pandemic Period: A Mixed Model Research

The COVID-19 pandemic has increased the likelihood of burnout among healthcare workers, as well as the likelihood of burnout-related hazards. The study aims to explore burnout in healthcare professionals and the specific changes and challenges brought on by the epidemic. Participants complete the Maslach Burnout Scale Short Form and answer four open-ended questions through Google Forms. The impact of occupation on burnout is minimal, with only slight differences observed between physicians, nurses, and other healthcare workers. Change in working hours is associated with higher levels of burnout compared to unchanged working hours. Participants with low and very low levels of burnout report more occupational changes, while those with high and very high burnout levels experience more psychological difficulties. High burnout levels are associated with challenges in working conditions, mask-equipment use, and psychological well-being. These findings are consistent with previous research linking increased workload, alterations in work environment, and psychological difficulties to burnout during the COVID-19 pandemic. In general, the findings align with previous studies that highlight the impact of changes in the work environment, increased workload, and psychological factors on burnout.

Exploring the impact of bioactive compounds on endothelial dysfunction in hypertensive individuals: a comprehensive systematic review

Systemic Arterial Hypertension is considered the main risk factor for cardiovascular diseases and is also associated with a pro-oxidative environment and endothelial alterations. The objective of this review was to evaluate the evidence available in the literature regarding the impact of resveratrol, quercetin, and catechin consumption on endothelial function in individuals with arterial hypertension. The search was conducted using the PICOS strategy across the following databases: Science Direct, Pubmed, Scielo, and Lilacs. The inclusion criteria comprised adults and the elderly of both sexes, with a body mass index above 18.5 kg/m², diagnosed with arterial hypertension. Resveratrol and quercetin were found to have a positive effect on the vascular endothelium by increasing flow-mediated dilation. Additionally, quercetin alone led to a reduction in blood pressure among hypertensive individuals. However, due to limitations in the available studies, it was not possible to reach a conclusive result regarding catechin. Further studies are needed to evaluate its effect. Therefore, including food sources rich in resveratrol and quercetin may prove beneficial for individuals with this chronic non-communicable disease.

From soil to clinic: current advances in understanding Coccidioides and coccidioidomycosis.

SUMMARYCoccidioides immitis and Coccidioides posadasii are fungal pathogens that cause systemic mycoses and are prevalent in arid regions in the Americas. While C. immitis mainly occurs in California and Washington, C. posadasii is widely distributed across North and South America. Both species induce coccidioidomycosis (San Joaquin Valley fever or, more commonly, Valley fever), with reported cases surging in the United States, notably in California and Arizona. Moreover, cases in Argentina, Brazil, and Mexico are on the rise. Climate change and environmental alterations conducive to Coccidioides spp. proliferation have been recently explored. Diagnostic challenges contribute to delayed treatment initiation, compounded by limited therapeutic options. Although antifungal drugs are often effective treatments, some patients do not respond to current therapies, underscoring the urgent need for a vaccine, particularly for vulnerable populations over 60 years old relocating to endemic areas. Despite recent progress, gaps persist in the understanding of Coccidioides ecology, host immune responses, and vaccine development. This review synthesizes recent research advancements in Coccidioides ecology, genomics, and immune responses, emphasizing ongoing efforts to develop a human vaccine.

Assessing ecosystem resilience: effects of different environments on native flora, lichens and bee pollen in a mid-sized Brazilian city

Abstract The alteration of the natural environment by human activities has increased in recent decades, with a significant impact on the organisms that inhabit it. One of the most apparent consequences of environmental alterations is the occurrence of climatic changes. The city of Joinville is situated in the southern region of Brazil. It has achieved a notable position at the national level, largely due to the significant presence of large-scale industrial operations in the metal-mechanical, plastic, and textile sectors. This study aimed to assess the effects of urban environments on Nectandra oppositifolia plants and lichen communities using a passive biomonitoring approach, and on Tetragonisca angustula stingless bees using an active biomonitoring approach. This study demonstrated a pronounced effect of anthropogenic activities on plant anatomy and morphology (higher leaf area, fresh mass, dry mass, and water content in the urban-industrial site), with higher metal concentrations in leaf particulate matter (3.14 ± 0.4 μg cm−2). The diversity of lichens was the lowest, whereas that of crustose lichens was the highest in industrial-urban and residential-rural sites (industrial-urban site = 13 species, residential-rural site = 29 species, control site = 33 species, p < 0.05). The distribution of species within the lichen communities was inversely correlated with the degree of anthropogenic influence. Some lichen species were found exclusively in the control areas, suggesting that they may indicate good environmental quality (Arthonia sp., Astrothelium sp., Phyllopsora pyxinoides, Phyllopsis sp., and others). Beehive pollen analysis revealed the presence of Zn, Cr, Ni, Cu, and Pb, and industrial-urban site exhibited higher metal concentrations (particularly, Ni, 12.59 ± 0.9, and Cr, 3.76 ± 1.00, mg kg−1). This approach highlights the environmental repercussions that affect the Plantae, Fungi, and Animalia kingdoms. The use of biomonitoring as a robust tool in good environmental quality assessment provides insight into policy decisions and underscores the importance of pollution studies.

Investigating the resistome of haemolytic bacteria in Arctic soils.

Microorganisms inhabiting hostile Arctic environments express a variety of functional phenotypes, some of clinical interest, such as haemolytic ability and antimicrobial resistance. We studied haemolytic bacterial isolates from Arctic habitats, assessing their minimum inhibitory concentration (MIC) against antimicrobials. We then performed whole genome sequencing and analysed them for features conferring antimicrobial resistance. MIC data showed that Micromonospora spp. belong to 33% non-wild type (NWT) for erythromycin and penicillin and 22% NWT for tetracycline. Both Pseudomonas spp. belong to 43% NWT for nalidixic acid and streptomycin and 29% NWT for colistin. Finally, the Pedobacter isolate was in 80% NWT for antimicrobials tested. Whole-genome sequencing analyses revealed that fluoroquinolones, tetracyclines, macrolides and penams were the most frequent drug classes against which genotypic resistance was found. Additionally, resistance genes to heavy metals and disinfectants were identified. Our research demonstrates the presence of antimicrobial resistance in bacteria from Arctic habitats and highlights the importance of conservation efforts in these environments, where anthropogenic influence is becoming more evident. Furthermore, our data suggest the possible presence of novel resistance mechanisms, which could pose a threat if the responsible genes are transferable between species or become widespread due to environmental stress and alterations brought about by climate change.

Regulating the Zn electrode/electrolyte interface with lactose additive for high performance Zn anode

The practical utilization of rechargeable aqueous zinc metal batteries (AZMBs) has been constrained by the formation of zinc dendrites and other associated issues. This article introduces lactose, a compound rich in hydroxyl groups, as an electrolyte additive into the aqueous solution of the electrolyte with the objective of suppressing the harmful growth of zinc dendrites. The lactose additive, with its strong zincophilicity, robust intermolecular hydrogen bonding, and a large number of exposed high electronegativity hydroxyl groups, enables lactose to effectively modulate the electrode/electrolyte interface in a dynamic manner, thereby achieving the stability and reversibility of the zinc anode. The findings presented in this work demonstrate the uniform deposition and stripping of zinc in a 2 M ZnSO4 electrolyte with the addition of lactose, thereby enhancing the cycling performance of Zn||Zn batteries. The alteration of the zinc ion environment on the surface of the zinc electrode, in conjunction with the dynamic modulation of the Gouy-Chapman-Stern (GCS) layer by lactose, increases the nucleation overpotential, thereby facilitating to a uniform deposition morphology in lieu of the formation of large-scale dendrites. Furthermore, the formation of hydrogen bonds serves to prevent the occurrence of side reactions. These factors act in concert to enhance the electrochemical performance of AZMBs. The addition of lactose to the electrolyte has resulted in a significant enhancement in the Coulombic efficiency of the card-type Zn||Cu asymmetric battery, reaching 99.7 %. The biodegradability of lactose and the sustainability of its source make this research conducive to the development of environmentally friendly battery electrolyte additives.

A heterogenous-source geoinformation system to manage climate-induced modifications on the landscape for sustainable development

Historical landscapes in Italy have been slowly changing over the centuries and this is because their features, once fixed into specific shapes, were perpetuated until new economic and social developments occurred. Yet, in the Alpine region, this territorial organisation underwent sudden changes after World War II (WW II), resulting in a loss in population and traditional agropastoral production in favour of skiing plants and holiday houses. Moreover, the loss of traditional knowledge pertaining to environmental behaviour has resulted in the urbanisation of lands that are vulnerable to extreme events. In turn, this has hindered sustainable urban development. Nowadays, modern mapping technologies enable the state of the landscape to be assessed before, during, and after extreme events, the increased frequency of which may be related to climate change. The case study examined in this paper is the flood that hit Limone Piemonte, Italy, between the 2nd and 3rd October 2020. On that occasion, an aerial survey of the affected areas was carried out using Uncrewed Aerial Vehicles (UAV) a few weeks after the event. Spatial analyses were also performed based on very high-resolution satellite imagery acquired a few days after the event in order to determine where to plan more detailed three-dimensional (3D) surveys. This has enabled assessments of damages at different map scales to be performed. Thanks to the availability of pre-event multitemporal cartographic reference datasets, it was possible to monitor the historical evolution of the affected areas. It was possible to assess the vulnerable areas before the event, as well as to evaluate the morphological and settlement changes after the disaster. Therefore, one of the goals of this manuscript is to demonstrate that geoinformation systems are among the primary technical tools used to analyse environmental and climatic alterations that impact landscapes. Finally, a 3D model of the affected areas was produced, fulfilling another goal of the research by providing the public administration with a sustainable and innovative tool for territorial and landscape management, in accordance with the 11th pillar of the United Nations Sustainable Development Goals (UN SDGs).

Climate Change and Public Health Dynamics: A Bibliometric Study with Comprehensive Review

The study directs to analyze how global climate shift affects public well-being and identify research clusters, trends, and potential gaps in this multidisciplinary field. The study also investigates the worldwide distribution of research institutions and their collaborative networks in this crucial area. We have use advanced bibliometric techniques to achieve our objectives. The analysis involves numerous academic articles, including journals, authors, keyword co-occurrence, and affiliations. By mapping the intellectual composition and trends in the field, we can gain valued perceptions of the complex relationship involving environmental alteration and public well-being. Bibliometric data is used to track research themes and clusters over time, examining keyword co-occurrence and affiliations. A comprehensive dataset of 1854 research papers was acquired from January 2000 to July 2023. Geospatial analysis helps us understand the geographic distribution of research institutions. Research papers were collected on climatic variations and people's physical conditions from the Web of Science portal, the report includes a bibliometric analysis and methodology review. Our study highlights research clusters and evolving themes in climatic disturbances and public wellbeing, along with potential study gaps. Furthermore, it examines the global reach of this critical field by analyzing the geographic distribution of research institutions and their collaborative networks. This review specifies a broad view of climate difference's impact on public health. It helps identify trends and promotes interdisciplinary collaborations. Use it to shape evidence-based strategies for mitigating climate changes health effects in the 21st century.

Differential Cytoophidium Assembly between Saccharomyces cerevisiae and Schizosaccharomyces pombe.

The de novo synthesis of cytidine 5'-triphosphate (CTP) is catalyzed by the enzyme CTP synthase (CTPS), which is known to form cytoophidia across all three domains of life. In this study, we use the budding yeast Saccharomyces cerevisiae and the fission yeast Schizosaccharomyces pombe as model organisms to compare cytoophidium assembly under external environmental and intracellular CTPS alterations. We observe that under low and high temperature conditions, cytoophidia in fission yeast gradually disassemble, while cytoophidia in budding yeast remain unaffected. The effect of pH changes on cytoophidia maintenance in the two yeast species is different. When cultured in the yeast-saturated cultured medium, cytoophidia in fission yeast disassemble, while cytoophidia in budding yeast gradually form. Overexpression of CTPS results in the presence and maintenance of cytoophidia in both yeast species from the log phase to the stationary phase. In summary, our results demonstrate differential cytoophidium assembly between Saccharomyces cerevisiae and Schizosaccharomyces pombe, the two most studied yeast species.

Dissolved organic matter (DOM) rather than warming and eutrophication directly affects partial pressure of CO2 (pCO2) in mesocosm systems

Environmental warming and eutrophication pose significant challenges to shallow lake systems, where dissolved organic matter (DOM) serves as a diverse and intricate mixture of organic macromolecules, playing a pivotal role in aquatic ecosystems. Despite its complexity, comprehending the interplay between environmental changes and DOM composition alterations and their subsequent impacts on aqueous CO2 partial pressure (pCO2) is essential for a better understanding of carbon cycling. Yet, our current understanding in this realm remains limited. To address this gap, mesocosm systems were established to investigate how elevated water temperature and eutrophication, alongside changes in DOM composition, influence pCO2 dynamics. Results indicate that while temperature and nutrient levels do not directly influence pCO2 fluctuations, they indirectly affect aqueous pCO2 through their modulation of DOM composition. Elevated temperature and nutrient concentrations notably enhance both the production and degradation of indigenous protein-like organic matter and increase the accumulation of humic-like organic compounds, with phosphorus released from sediment playing a particularly significant role. Furthermore, the degradation rate of protein-like organic matter significantly exceeds its accumulation rate. On the other hand, the impact of water eutrophication on DOM composition surpasses that of temporal temperature variations, with a 2∼4 °C temperature rise showing minimal effects on DOM composition. Notably, the degradation of protein-like organic matter markedly increases aqueous pCO2, while the rise in humic-like organic matter in water exerts minimal influence on pCO2 concentrations. A comprehensive understanding of carbon cycling processes under environmental changes will facilitate effective management of lake ecosystems and the advancement of carbon mitigation technologies.

The impact of the community's sound environment on social interactions among residents

The built environment significantly influences social interactions, which are crucial for residents, but little is known about how these interactions are affected by the community's sound environment. This study conducted sound intervention experiments in the community to investigate the impact of alterations in the sound environment on residents' social behaviours. The social interaction situations under five sound intervention conditions were recorded and evaluated from three dimensions: participation, occurrence, and depth. The results indicated that a more natural sound environment in the community leads to a higher proportion of socially interactive residents and an increased occurrence of social interactions among residents. Birdsong interventions increased paired social interactions by 16.3 % compared to traffic noise, while water sound interventions increased grouped social interactions by 16.6 % compared to the control. Compared to the frequency in the lowest group, individual prolonged pair social interactions increased by 0.26 occurrences with birdsong intervention, and prolonged group social interactions increased by 0.19 occurrences with water sounds intervention. The findings can inform community designers about the strategic use of sound to enhance the environment and promote social interactions among residents.

Land cover is the main driver of the distribution patterns of larval Odonata assemblages in freshwater wetlands of the Brazilian Pampa

AbstractAquatic insects are key to wetland ecological functioning, and the distribution of amphibious insects such as Odonata jointly depends on environmental conditions in the aquatic and terrestrial settings. Therefore, untangling the relative effects of within‐wetland and landscape composition can help predict the responses of Odonata to environmental alterations in wetlands. Using data from 19 wetlands spanning over the southern Brazilian Pampa (center‐western Rio Grande do Sul state), we assessed the relative importance of water chemistry and land‐cover variables to the richness and composition of larval Odonata assemblages (and suborders Anisoptera and Zygoptera). Anisoptera richness decreased with pH and bare soil area. Water pH and areas of bare soil, mosaic of agricultural land use, and waterbodies land cover were the main drivers of Odonata and Zygoptera composition. Our results indicate that land cover is the main driver of the assemblage structure of larval Odonata, although a complex interplay of mechanisms associated with land conversion and water quality drive the distribution of larval Odonata in freshwater wetlands of the Brazilian Pampa. The major implication of our findings is that land cover modification is the major threat to Odonata distribution in Pampean wetlands, with potential impacts on the trophic structure and functioning of these ecosystems.

Sensitivity of Alabama Freshwater Gastropod Species to Nickel Exposure.

Snails are effective bioindicators due to their prolific distribution, high level of endemism, and capacity to accumulate contaminants. Freshwater snails have unique ecological niches which are imperiled by land-use change and the introduction of hazardous chemicals. To assess how environmental alterations affect gastropods, lab-based studies are needed to characterize the toxicity of specific stressors. This can help guide policy decisions and remediation efforts. The aim of this research was to characterize acute toxicity of nickel (Ni) on endemic snails (Somatogyrus georgianus [Walker, 1904], Elimia cahawbensis [Lea, 1861], and Elimia spp.) and measure the accumulation of Ni and mineral elements including calcium (Ca), magnesium, potassium, and sodium (Na). Snails were exposed to six concentrations (25-800 µg/L) of Ni for 96 h. Among the studied snail species, E. cahawbensis was the most sensitive to Ni, with the lowest lethal concentration where 50% of the organisms died (LC50) at 88.88 µg/L Ni after 96 h. The LC50 at 96 h for S. georgianus was 167.78 µg/L Ni, and 393.13 μg/L Ni for Elimia spp. Except for Elimia spp., mortality of the other two snail species corresponded to the whole-body uptake of Ni. Nickel exposure also influenced Ca and Na uptake for Elimia spp. All three endemic species are potential candidate species for evaluating localized effects of human activities, and the present study provides a first step in characterizing how snails would be affected by environmental alterations. More research could further characterize potential effects of other human stressors on these endemic snail species. Future research into subindividual responses and routes of exposure can further elucidate variations in species sensitivity. Environ Toxicol Chem 2024;00:1-11. © 2024 SETAC. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.