Ecological Functions Research Articles

Microbial profiling of the East Siberian Sea sediments using 16S rRNA gene and metagenome sequencing

The Arctic Ocean is experiencing significant global warming, leading to reduced sea-ice cover, submarine permafrost thawing, and increased river discharge. The East Siberian Sea (ESS) undergoes more significant terrestrial inflow from coastal erosion and river runoff than other Arctic seas. Despite extensive research on environmental changes, microbial communities and their functions in the ESS, which are closely related to environmental conditions, remain largely unexplored. Here, we investigated microbial communities in ESS surface sediments spanning latitudes from 73°N to 77°N using 16S rRNA amplicon sequencing, and reconstructed 211 metagenome-assembled genomes (MAGs) using shotgun metagenome sequencing. Taxonomic analysis identified 209 bacterial MAGs, with the predominant phyla Pseudomonadota (n = 82), Actinobacteriota (n = 38), Desulfobacterota (n = 23), along with 2 archaeal MAGs of Thermoproteota. Notably, 86% of the MAGs (n = 183) could not be classified into known species, indicating the potential presence of novel and unidentified microorganisms in the ESS. This dataset provides invaluable information on the microbial diversity and ecological functions in the rapidly changing ESS.

Hydrodynamic Modelling of Severn Bore and Its Dependence on Ocean Tide and River Discharge

Owing to the high tidal range, the Severn Estuary and Bristol Channel have the potential to generate huge amounts of renewable electricity for the UK. During the flood tide, the surging water travels upstream to form the Severn Bore. This study explores the dynamics of the Severn Bore through hydrodynamic modelling, analyzing how the tidal amplitude, mean water level, and river discharge affect the bore’s intensity, reach, and sustainability. The Delft3D simulations show that the downstream tidal amplitude plays a critical role. Tides with an amplitude of less than 6 m will lead to the disappearance of the Severn Bore. The mean water level also significantly influences the bore’s propagation, with a 1.5 m drop resulting in a 15 km retreat of the bore. A high river discharge rate weakens the bore’s intensity and reduces its reach. These findings underscore the need for careful planning in tidal energy development within the Severn Estuary. Excessive exploitation of tidal energy can be detrimental to the Severn Bore and the ecological function of the estuary.

Uncharted territory: the arrival of Psychoda albipennis (Zetterstedt, 1850) (Diptera: Psychodidae) in Maritime Antarctica

Despite increasing awareness of the threats they pose, exotic species continue to arrive in Antarctica with anthropogenic assistance, some of which inevitably have the potential to become aggressively invasive. Here, we provide the first report of the globally cosmopolitan species Psychoda albipennis (Diptera, Psychodidae; commonly known as moth flies) in Antarctica during the austral summer of 2021/2022, with the identification confirmed using traditional taxonomic and molecular approaches. The species was present in very large numbers and, although predominantly associated with the drainage and wastewater systems of Antarctic national operator stations in synanthropic situations, it was also present in surrounding natural habitats. While it is unclear if P. albipennis is capable of long-distance dispersal, adult psychodid flies are known to travel more than 90 m from their emergence sites, and up to 1.5 km with wind assistance. Thus, once established in the natural environment of King George Island there appears to be a high risk of the species rapidly becoming invasive. The introduction of non-native species such as P. albipennis can be a significant driver of future biodiversity change and loss, and seriously impact ecosystem health. In vulnerable low diversity ecosystems, such as in the terrestrial environments of Antarctica, non-native species can lead to step changes in ecological functions and interactions, displace native species and, potentially, lead to the extinction of native biota.

Ecosystem services assessment of Beledanga oxbow lake in the Gangetic plains: pathways to sustainable conservation

Oxbow lakes, formed from abandoned river meanders, are unique wetlands that play a crucial role in supporting aquatic biodiversity and sustaining local communities through their ecosystem services. This study focuses on the Beledanga oxbow lake, highlighting its ecosystem services and the critical role of hydrological connectivity with the adjacent river for maintaining ecological functionality and sustainability. Using the Millennium Ecosystem Assessment framework, the study assessed provisioning, regulating, cultural, and supporting services through field surveys, stakeholder consultations, and secondary data analysis. Results show that the lake provides essential provisioning services, such as fisheries and irrigation, which support local food security and income generation. It also plays a role in regulating services like water management and carbon sequestration, while its biodiversity underpins vital ecological functions, including nutrient cycling and habitat provision. However, challenges such as seasonal water scarcity and macrophyte infestation threaten the lake's productivity and connectivity with the river. The study emphasizes the need for collaborative efforts involving local stakeholders to devise water management strategies and remove macrophytes, utilizing government initiatives like the Mahatma Gandhi National Rural Employment Guarantee Act (MGNREGA) for funding. Additionally, the establishment of robust monitoring systems for sustainable fisheries management and incentive programs for conservation efforts are recommended. The research highlights the importance of hydrological connectivity in sustaining the lake's ecosystem services and enhancing biodiversity. By integrating local knowledge and stakeholder engagement, this study provides valuable insights into the sustainable management of oxbow lakes and highlights the broader significance of river-oxbow lake connectivity in wetland conservation efforts. The findings also have implications for broader wetland conservation policies in similar ecosystems.

Ecosystem Services Trade-Offs in the Chaohu Lake Basin Based on Land-Use Scenario Simulations

Amid global environmental degradation, understanding the spatiotemporal dynamics and trade-offs of ecosystem services (ESs) under varying land-use scenarios is critical for advancing the sustainable development of social–ecological systems. This study analyzed the Chaohu Lake Basin (CLB), focusing on four scenarios: natural development (ND), economic priority (ED), ecological protection (EP), and sustainable development (SD). Using the PLUS model and multi-objective genetic algorithm (MOGA), land-use changes for 2030 were simulated, and their effects on ESs were assessed quantitatively and qualitatively. The ND scenario led to significant declines in cropland (3.73%) and forest areas (0.18%), primarily due to construction land expansion. The EP scenario curbed construction land growth, promoted ecosystem recovery, and slightly increased cropland by 0.05%. The SD scenario achieved a balance between ecological and economic goals, maintaining relative stability in ES provision. Between 2010 and 2020, construction land expansion, mainly concentrated in central Hefei City, led to a marked decline in habitat quality (HQ) and landscape aesthetics (LA), whereas water yield (WY) and soil retention (SR) improved. K-means clustering analysis identified seven ecosystem service bundles (ESBs), revealing significant spatial heterogeneity. Bundles 4 through 7, concentrated in mountainous and water regions, offered high biodiversity maintenance and ecological regulation. In contrast, critical ES areas in the ND and ED scenarios faced significant encroachment, resulting in diminished ecological functions. The SD scenario effectively mitigated these impacts, maintaining stable ES provision and ESB distribution. This study highlights the profound effects of different land-use scenarios on ESs, offering insights into sustainable planning and ecological restoration strategies in the CLB and comparable regions.

Does Green Finance Enhance the Ecological Value Level of Cultivated Land? Evidence from Mainland China

The ecological value of cultivated land contributes to a harmonious agricultural environment. Green finance support is essential to promoting the ecological value of cultivated land. Nevertheless, research specifically centered on cultivated land as a primary focus remains limited in exploring the relationship between ecological value and green finance, ignoring the fact that green finance can bolster ecological functions and drive sustainable practices. To address this gap, an objective indicator of the cultivated land ecological value level was introduced, and its variations at both the provincial and national levels from 2003 to 2022 were investigated. Results indicate that the cultivated land ecological value level increased over time, with higher values clustering spatially in southern regions. Subsequently, specific spatial correlations between the cultivated land ecological value level and green finance support were revealed using a spatial Durbin model. The results show that green finance support enhanced the cultivated land ecological value level, with its spatial lag term being particularly pronounced. These correlations were evident in eastern regions but were insignificant in western regions. Furthermore, a detailed range of spatial indirect spillover effects was estimated, demonstrating that the spatial effects on other provinces were positive when the geographic distance between them was close. In summary, these conclusions offer practical recommendations for the eco-friendly management of cultivated land, including strategies for vertical collaboration between central and local administrations and horizontal adaptation by governments in the east, central, and west regions based on local conditions.

The role of anthropogenic influences on a tropical lake ecosystem and its surrounding catchment: a case study of Lake Sentani.

Lake Sentani is a tropical lake in Indonesia, consisting of four interconnected sub-basins of different water depths. While previous work has highlighted the impact of catchment composition on biogeochemical processes in Lake Sentani, little is currently known about the microbiological characteristics across this unique ecosystem. With recent population growth in this historically rural area, the anthropogenic impact on Lake Sentani and hence its microbial life is also increasing. Therefore, we aimed to explore the influence of environmental and anthropogenic factors on the microbial diversity of Lake Sentani. Here we present a detailed microbiological evaluation of Lake Sentani, analyzing 49 different sites across the lake, its tributary rivers and their river mouths to assess diversity and community structure using 16S rRNA gene sequencing. Our results reveal distinct communities in lake and river sediments, supporting the observed geochemical differences. Taxonomic assessment showed the potential impact of anthropogenic pressure along the northern, urbanized shore, as river and river mouth samples revealed high abundances of Bacteroidota, Firmicutes and Cyanobacteria, which could be attributed to pollution and eutriphication. In contrast, lake sediment communities were dominated by Thermodesulfovibrionia, Methanomethylicia, Bathyarchaeia and Thermoplasmata, suggesting sulfate reducing, thermophilic, acidophilic bacteria and methanogenic archaea to play an important role in tropical lake systems. This study provides novel insights into ecological functions of tropical lakes and contributes to the optimization of management strategies of Lake Sentani, ensuring its holistic preservation in the future.

Microbial functional diversity and redundancy: moving forward.

Microbial functional ecology is expanding as we can now measure the traits of wild microbes that affect ecosystem functioning. Here, we review techniques and advances that could be the bedrock for a unified framework to study microbial functions. These include our newfound access to environmental microbial genomes, collections of microbial traits, but also our ability to study microbes' distribution and expression. We then explore the technical, ecological, and evolutionary processes that could explain environmental patterns of microbial functional diversity and redundancy. Next, we suggest reconciling microbiology with biodiversity-ecosystem-functioning studies by experimentally testing the significance of microbial functional diversity and redundancy for the efficiency, resistance, and resilience of ecosystem processes. Such advances will aid in identifying state shifts and tipping points in microbiomes, enhancing our understanding of how and where will microbiomes guide Earth's biomes in the context of a changing planet.

Actively soniferous tropical reef fishes are diverse, vulnerable, and valuable.

Active (i.e., intentional) fish sound production provides informative cues for numerous ecological functions, including larval recruitment or reproduction, and can facilitate monitoring and restoration. It is therefore important to have a holistic picture of actively soniferous tropical reef fish diversity, particularly in the face of growing threats such as noise pollution and habitat degradation. This study integrates fish biodiversity and sonifery datasets to assess the prevalence and ecological characteristics of actively soniferous tropical reef fishes. There are 258 known sound-producing species, which span 46 families, encompass a variety of life-history (e.g., lifespan) and distribution (e.g., depth) attributes, and include many vulnerable and commercially valuable species. Furthermore, up to 75% of tropical reef fish species are considered likely to produce active sounds. This synthesis should encourage a greater appreciation for active fish sound production in tropical reef environments and advance efforts to incorporate soundscape ecology into management and restoration strategies.

Nature-Based Solutions Planning for Urban Microclimate Improvement and Health: An Integrated Ecological and Economic Approach

Nature-based Solutions (NbSs) play a pivotal role in mitigating the impact of microclimates on human well-being. The effectiveness of NbSs is contingent upon the synergy between natural capital, defined by the ecological structure and functions of the ecosystem, and human-derived capital, encompassing the economic investments required for implementation. This study introduces a decision-making framework designed to evaluate the impact of NbSs and advocate for optimal solutions for human health at the local scale, amalgamating ecological and economic assessments. Physiological Equivalent Temperature (PET) was chosen as a key urban parameter to assess the efficacy of NbSs in mitigating urban microclimates and enhancing human health. The PET analysis was conducted using ENVI-met 5.0.3 software across diverse urban scenarios in Gallipoli city, Italy. Integrated with a cost–benefit analysis of NbSs considering various investment scenarios, the study aimed to identify the most effective solution. Results indicated positive effects of NbSs in open spaces and around building blocks where the PET levels remained below 30 °C. Conversely, scenarios without NbSs exhibited PETs exceeding 40 °C, with peaks of 50 °C, posing potential risks to human health. Considering the social and economic benefits associated with PET mitigation, the cost–benefit analysis suggests that implementing NbSs using a mix of young and mature plants in the initial phase is advantageous compared to using only young plants. Thus, in establishing NbSs, it is crucial to consider not only the quantity of vegetation but also the strategic timing of implementation. In conclusion, our work offers an innovative framework that combines ecological and economic perspectives, providing valuable insights for decision-makers in urban planning and promoting the practical application of NbSs for enhanced human well-being.

Microbial community structure and functional traits involved in the adaptation of culturable bacteria within the gut of amphipods from the deepest ocean.

Amphipods are widely distributed in the Hadal trenches, and the study of their gut microbes has garnered considerable scientific interest. Our research breaks away from traditional omics approaches, innovatively combining sequencing technologies with culture-dependent methods to analyze the gut microbiome structure of amphipods from the Mariana Trench. This not only complements the current omics-dominated field but also paves the way for future resource development of extreme microbes. Furthermore, by conducting genomic analyses and functional validations on a representative strain, we have uncovered its probiotic effects and strategies for adapting to extreme environments. This provides new insights into the theoretical study of the ecological functions of deep-sea bacteria. Overall, our findings offer a fresh perspective on the microbial community structure and environmental adaptation strategies of gut microorganisms in the Hadal Zone.

Soil-Easily Extractable Glomalin: An Innovative Approach to Deciphering Its Molecular Composition under the Influence of Seasonality, Vegetation Cover, and Wildfire.

Easily extractable glomalin (EEG) is a fraction of soil organic matter thought to contain mainly glomalin-related soil glycoproteins produced by mycorrhizal fungi. The EEG has an impact on various soil ecological functions, primarily related to soil aggregation formation and stability as well as water repellence. Here, analytical pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) was used for studying the molecular composition of soil EEG, and a detailed description of the chemical composition is reported. Samples extracted from Mediterranean soils under different vegetation covers (Pinus halepensis and shrubland species, Rosmarinus officinalis, and Brachypodium spp, predominantly), impacted or not by forest fires and collected at different times, were studied. A total of 139 compounds were identified and grouped based on their probable biogenic origin. The EEG chemical composition is dominated by lipids, aromatic compounds, steranes, and hydroaromatics with a remarkable abundance of compounds from plant origin. Significant EEG structural changes can indicate environmental disturbances such as those after a wildfire. The EEG soil organic fraction is found to be a stable and heat-resistant material in nature if soil temperatures remain below 200-250 °C. This study advances the understanding of EEG by providing a detailed molecular characterization and highlighting its role as a stable, heat-resistant component of soil organic matter in Mediterranean ecosystems. The main findings indicate that while EEG is structurally resilient and mostly originates from plant material, its composition is more similar to that of humic acids than to that of glycoproteins.

Response and Assembly Process of Soil Microbial Communities Under Different Reclamation Measures

Reclamation is essential for restoring the ecological function of soil in mining areas. However, the microbiological mechanism of soil ecological function reconstruction under different reclamation measures still needs to be clarified. Clarifying the characteristics of soil bacterial and fungal communities, assembly mechanisms, and their relationship with physicochemical properties under different reclamation measures is crucial for reshaping the ecological stability of soil in mining areas. Metagenomic sequencing technology was combined with the null model and neutral model to analyze the differences in soil microbial diversity, community composition, network structure, and community assembly process between the reclaimed natural recovery area （LH） and the reclamation fertilization area （MM）. The results suggested that： ① Compared with that in the LH treatment, the MM treatment significantly increased the soil nutrient content, and the total nitrogen （TN）, total phosphorus （TP）, available phosphorus （AP）, and available potassium （AK） contents increased by 34.70%, 72.72%, 468.98%, and 45.74%, respectively （P<0.05）. ② The dominant bacterial and fungal communities did not change under the LH and MM treatments； however, the abundance of bacterial communities changed significantly. Compared with that in the LH treatment, the relative abundance of Acidobacteria increased significantly by 5.4% in the MM treatment, while the relative abundance of Candidatus Rokubacteria decreased significantly by 235.72% （P<0.05）. Under different reclamation measures, the indicator microorganisms of bacterial and fungal communities changed. ③ Compared with that in the LH treatment, the MM treatment increased the complexity of bacterial networks, decreased the complexity of fungal networks, and increased the number of soil bacterial nodes and links. The reclamation measures transformed the key bacterial groups from Proteobacteria to Candidatus Rokubacteria and Planctomycetes. The key group of fungi was Ascomycota. 4.） The deterministic process dominated the assembly of bacterial and fungal communities. Homogeneous selection contributed the most to the bacterial community assembly in the LH treatment, and heterogeneous selection contributed the most to the MM treatment. The fungal communities were all dominated by heterogeneous selection. These results provide new insights into the soil microbial community structure and ecological function restoration in coal mining subsidence reclamation areas.

Chemical Warfare in the Environment-Secondary Metabolites From Starfish (Asterias amurensis) Induce Teratogenicity in Medaka Embryos (Oryzias melastigma).

Starfish saponins, known for their role as feeding deterrents against predators like crabs and fish, have been extensively studied for their antifeedant and cytolytic effects. Recent research suggests that starfish secondary metabolites possess antifouling and antifeedant properties and play a role in biological interactions and various ecological functions. Previous research demonstrated that saponins from starfish exert their toxic effects on fish by interacting with cholesterol in the blood cell membrane. This study investigated the hypothesis that secondary metabolites, other than saponins, from the starfish Asterias amurensis may be harmful to fish eggs, particularly marine medaka (Oryzias melastigma) eggs, which share starfish habitat. We systematically separated the secondary metabolites of A. amurensis by a variety of chromatographic methods. Two oligoglycosides related to embryonic teratogenicity were identified, including one previously undescribed tetrasaccharide (1) and one known pyrrole oligoglycoside (2). Their structures were established mainly on the basis of detailed analysis of the nuclear magnetic resonance spectroscopy (NMR) and mass spectroscopic data. Compounds 1 and 2 exhibited strong lethality and significantly reduced voluntary movements in medaka embryos, with compound 2 showing more pronounced effects on teratogenicity and heart rates. The main morphological abnormalities observed included delayed head development (DHD), tiny spines (TS), incomplete absorption of oil balls (OB), cardiac abnormalities (CA), and shrunken yolk sacs (SYS). Our findings imply that starfish secondary metabolites may have broader ecological effects, influencing habitat-sharing species in subtle but crucial ways.

Rights of nature and non-use of nature for environmental protection in Antarctica

ABSTRACT This article examines whether and to what extent a traditional international law regime can step in for the rights of nature, which are not yet recognised at the international level. It proceeds by analysing whether non-use measures in the Antarctic Treaty System (ATS), such as the suspension of fishing within marine protected areas, the moratorium on mining, and the restrictions to entry into Antarctic Specially Protected Areas, reflect the aims and values of the rights of nature and contribute to achieving the content of the rights of nature’s substantive and procedural rights. The focus on non-use measures is important as this is the type of conservation and management measures that, at least on paper, provide the highest possible form of environmental protection; use is prohibited and nature is hence given priority. This article finds that the aims of the non-use measures examined are quite reflective of fundamental elements of the rights of nature, but that ecocentric values are often accompanied by anthropocentric ones, especially in the older instruments. When it comes to substantive rights, while non-use measures adopted under the ATS have the potential to protect elements of nature and ensure that they can continue to exist and fulfil ecological functions, important issues remain, in particular exceptions and the limited material scope of non-use measures. Most problematic are procedural rights. While some noteworthy procedures enable a variety of interests to be represented and some checks and balances exist to promote compliance with obligations, States closely control key decision-making stages. In particular, the adoption of new non-use measures through consensus places the bar very high for their potential expansion. While non-use measures cannot replace the rights of nature, some best practices reflective of more ecocentric values and rights are noted, which could be further developed within the ATS or used in other regimes’ modifications or development.

KUALITAS RUANG TERBUKA HIJAU (RTH) PRIVAT PADA RUMAH TINGGAL DI DESA PEGUYANGAN KANGIN DITINJAU DARI SEGI EKOLOGIS

Population growth results in increasing demand for residential space and built-up land. This will have an impact on the environment, namely reducing the quality of green open spaces in carrying out ecological functions. As happened in Denpasar City, one of which is in the North Denpasar area. The availability of green open space in Denpasar City is dominated by private green open spaces originating from residential areas, namely residential yards. However, as in the Peguyangan Kangin Village Area, even though it is dominated by residential areas where land use is privately owned, the provision of private open space is actually very minimal. It is feared that this dynamic will have a negative impact on the surrounding environment in the future. Therefore, it is important to carry out this research with the aim of analyzing the quality of private green open space in terms of its ecological function and the availability of private green open space in the Peguyangan Kangin Village area. This research uses a qualitative method with a descriptive approach. The object of research will focus on private green open space in residential yards in Peguyangan Kangin Village. The research results show that in general the quality of private green open space in residential yards in the Peguyangan Kangin area is not optimal, both in terms of area and vegetation in carrying out ecological functions. The research results also show that there are several factors that influence the quality of private green open space, one of the most dominant of which is land availability.

Ecological erosion and expanding extinction risk of sharks and rays.

The true state of ocean biodiversity is difficult to assess, and there are few global indicators to track the primary threat of overfishing. We calculated a 50-year Red List Index of extinction risk and ecological function for 1199 sharks and rays and found that since 1970, overfishing has halved their populations and their Red List Index has worsened by 19%. Overfishing the largest species in nearshore and pelagic habitats risks loss of ecomorphotypes and a 5 to 22% erosion of functional diversity. Extinction risk is higher in countries with large human coastal populations but lower in nations with stronger governance, larger economies, and greater beneficial fisheries subsidies. Restricting fishing (including incidental catch) and trade to sustainable levels combined with prohibiting retention of highly threatened species can avert further depletion, widespread loss of population connectivity, and top-down predator control.

From typology to criteria considered by farmers: what explains agroecological practice implementation in North-Sudanian Burkina Faso?

Cropping systems in the North-Sudanian zone of Burkina Faso face significant challenges related to poor yields, declining soil fertility and harsh climatic conditions. Together these necessitate a shift toward more sustainable farming practices. Agroecology aims to enhance yields while minimizing environmental harm through the use of ecological functions and has been promoted by researchers and farmers’ organizations as a solution. However, its implementation remains limited. This study investigated the criteria farmers consider when implementing agroecological practices at the farm level and how these criteria and their implementation are influenced by farm characteristics. Data collection methods included the serious game TAKIT, together with baseline and complementary household surveys (108 farmers each). Farm diversity was analyzed using a statistical typology. The influence of farm types, farm structural variables and the village location on (1) whether or not agroecological practices were implemented and (2) the criteria considered by farmers was explored. Four distinct farm types were identified: low resource endowed farms relying on off-farm income, low resource endowed farms relying on livestock income, medium resource endowed farms relying on agricultural and livestock income, and high resource endowed farms with diverse sources of income. There were no significant differences in the implementation of agroecological practices across farm types. Crop rotations were the most frequently implemented practice (by 91% of the study farmers), while the 2-by-2 line intercropping of sorghum-cowpea was the least implemented (9% of farmers). Implementation of zai pits varied significantly between villages, with farmers in Nagreonkoudogo more likely to use them than those in Tanvousse, due to differing soil characteristics. Farmers considered several criteria when deciding whether to implement agroecological practices, including the ability to improve yield and preserve soil. Constraints to their implementation included a lack of knowledge and their high labor requirements. These criteria did not differ across farm types, likely because they stem from shared environmental constraints or conditions. The study highlights the complexity of agroecological transitions in sub-Saharan Africa, and illustrates the need to adequately consider contextual conditions. The co-design of new practices, and the redesign of existing ones, should align with criteria considered by farmers.

Evaluating the Impact of Environmental Factors on Bacterial Populations in Riverine, Estuarine, and Coastal Sediments

Aquatic ecosystems, including rivers, estuaries, and coastal environments, are crucial for maintaining biodiversity, regulating nutrient cycles, and supporting human livelihoods. However, these ecosystems are increasingly being threatened by urbanization, making it essential to understand their microbial communities and their ecological roles. This study employed high-throughput 16S rRNA gene sequencing to characterize the bacterial communities within the riverine, estuarine, and coastal sediments of Adyar Creek, Chennai, India. Proteobacteria were the dominant phylum across most samples, with proportions ranging from 39.65% to 72.09%. Notably, the estuarine environment exhibited a distinct taxonomic profile characterized by a significant abundance of Firmicutes (47.09% of the bacterial population). Distinct bacterial classes were observed across sediment types: Alphaproteobacteria (30.07–34.32%) in riverine sediments, Bacilli dominated estuarine sediments (40.17%), and Gammaproteobacteria (15.71–51.94%) in coastal sediments. The most significant environmental factors influencing the bacterial community composition across these samples were pH, salinity, phosphate, and nitrate. LEfSe (Linear discriminant analysis Effect Size) analysis identified specific genera within the estuary, including Bacillus (20.26%), unclassified_Paenibacillus (12.87%), Clostridium (3.81%), Gailella (3.17%), Paenibacillus (3.02%), Massilia (1.70%), Paraburkholderia (1.42%), and Pantoea (1.15%), as potential biomarkers for habitat health. Functional analysis revealed an elevated expression of the genes associated with ABC transporters and carbon metabolism in the estuary, suggesting a heightened nutrient cycling capacity. Furthermore, co-occurrence network analysis indicated that bacterial communities exhibit a strong modular structure with complex species interactions across the three sediment types. These findings highlight bacterial communities’ critical role and the key drivers in estuarine ecosystems, establishing a baseline for further investigations into the functional ecology of these vulnerable ecosystems.

Multi-compartment impact of micropollutants and particularly antibiotics on bacterial communities using environmental DNA at river basin-level.

Bacterial communities respond to environmental conditions with diverse structural and functional changes depending on their compartment (water, biofilm or sediment), type of environmental stress, and type of pollution to which they are exposed. In this study, we combined amplicon sequencing of bacterial 16S rRNA genes from water, biofilm, and sediment samples collected in the anthropogenically impacted River Aconcagua basin (Central Chile, South America), in order to evaluate whether micropollutants alter bacterial community structure and functioning based on the type and degree of chemical pollution. Furthermore, we evaluated the potential of bacterial communities from differently polluted sites to degrade contaminants. Our results show a lower diversity at sites impacted by agriculture and urban areas, featuring high loads of micropollution with pesticides, pharmaceuticals and personal care products as well as industrial chemicals. Nutrients, antibiotic stress, and micropollutant loads explain most of the variability in the sediment and biofilm bacterial community, showing a significant increase of bacterial groups known for their capabilities to degrade various organic pollutants, such as Nitrospira and also selecting for taxa known for antibiotic resistance such as Exiguobacterium and Planomicrobium. Moreover, potential ecological functions linked to the biodegradation of toxic chemicals at the basin level revealed significant reductions in ecosystem-related services in sites affected by agriculture and wastewater treatment plant (WWTP) discharges across all investigated environmental compartments. Finally, we suggest transitioning from simple concentration-based assessments of environmental pollution to more meaningful toxic pressure values, measured environmental concentrations normalised by effect information, in order to comprehensively evaluate the role of micropollutants at the ecological (biodiversity) level.