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PubMed1976

Toxicity of ammonia to algae in sewage oxidation ponds.

Ammonia, at concentrations over 2.0 mM and at pH values over 8.0, inhibits photosynthesis and growth of Scenedesmus obliquus, a dominant species in high-rate sewage oxidation ponds. Photosynthesis of Chlorella pyrenoidosa, Anacystis nidulans, and Plectonema boryanum is also susceptible to ammonia inhibition. Dark respiration and cell morphology were unaffected by any combination of pH and ammonia concentrations tested, thus limiting the apparent effect to inhibition of the normal function of the chloroplasts. Methylamine had the same effect as ammonia, and its penetration into the cells was found to be pH dependent. Therefore, the dependence of toxicity of amines to algae on pH apparently results from the inability to penetrate the cell membrane in the ionized form. When operated at 120-h detention time of raw wastewater, the high-rate oxidation pond maintained a steady state with respect to algal growth and oxygen concentration, and the concentration of ammonia did not exceed 1.0 mM. Shifting the pond to 48-h detention time caused an increase in ammonia concentration in the pond water to 2.5 mM, and the pond gradually turned anaerobic. Photosynthesis, which usually elevates the pH of the pond water to 9.0 to 10.0, could not proceed beyond pH 7.9 because of the high concentration of ammonia, and the algal population was washed out and reduced to a concentration that could maintain a doubling time of 48 h without photosynthesis bringing the pH to inhibitory levels. Under these conditions, the pH of the bond becomes a factor that limits the operational efficiency of the oxidation pond.

Ammonia↗

PubMed2026

Supplementation with effective microorganisms in earthen ponds affects common carp growth and abundance of specific bacterial families.

BACKGROUND: Effective microorganisms are increasingly explored in aquaculture to improve fish health and growth without leaving harmful residues. However, their efficacy in real-world pond environments remains poorly understood. Here, we conducted a 103-day field experiment to assess the effects of supplementation with two effective commercial microorganism products on the microbial communities and growth performance of common carp (Cyprinus carpio). BACKGROUND: Effective microorganisms were added to the feed and directly to the pond water. Microbial diversity was analysed via 16 S rRNA and whole-genome shotgun sequencing across three environments: water (three time points), sediment (two time points), and fish intestine (one time point) from 25 experimental ponds. Bioinformatics processing was performed using the QIIME2 and MG-TK pipelines with taxonomic classification based on the SILVA database. The results showed that although supplemented bacterial families did not establish significantly in pond environments, fish exposed to specific effective microorganism treatments showed improved growth metrics. CONCLUSIONS: These findings suggest that effective microorganisms can increase carp growth in aquaculture without significantly altering the resident microbial communities, suggesting a promising residue-free alternative to traditional additives in aquaculture.

Animals↗

PubMed2026

Genome sequences of pirAB+ and pirAB- Vibrio campbellii strains isolated from shrimp ponds with mortality outbreaks carry type VI secretion systems.

Vibrio campbellii strains PH1401 and PH1409 were isolated from shrimp ponds with documented mortality outbreaks in the Philippines. PH1401 and PH1409 share identity with V. campbellii strain BoB-53. Whole-genome analysis reveals full-length pirAB binary toxin genes in PH1401. Both strains carry three type VI secretion systems.

Vibrio campbellii↗

PubMed1975

[Contribution to the study of Microphallidae Travassos 1920 (trematoda). XXXII. Microphallus breviatus n. sp., a species with an abbreviated evolutive cycle from a Mediterranean pond in the Languedoc].

Contribution to the study of Microphallidae Travassos, 1920 (Trematoda). XXXII. - Microphallus breviatus n. sp., a short life-cycle species of a mediterranean pond of Languedoc. The whole larval life-cycle of M. breviatus takes place in one host, Hydrobia ventrosa (Montagu), Mollusc Hydrobiidae. Hepato-pancreatic sporocysts produce morphologically altered xiphidio-cercariae which become encysted metacercariae in the sporocyts themselves. This species is defined in the genus by the anatomic characteristics of its cercariae and metacercariae, allied with its uncommon biology including two hosts only.

France↗

PubMed1976

The anatomy of neurosecretory neurones in the pond snail Lymnaea stagnalis (L.).

The anatomy of three neurosecretory cell types in the central nervous system (c.n.s.) of the gastropod mollusc Lymnaea stagnalis (L.)- the Dark Green Cells, Yellow Cells and Yellow-green Cells-has been studied by using bright and dark field illumination of material stained for neurosecretion by the Alcian Blue-Alcian Yellow technique. The neuronal geometry of single and groups of neurosecretory cells of the various types has been reconstructed from serial sections, and the likely destination of most of their processes has been determined. Dark Green Cells are monopolar, occur exclusively within the central nervous system (c.n.s.), have few or no branches terminating in neuropile, and send axons to the surface of the pleuro-parietal and pleuro-cerebral connectives. The majority of Dark Green Cell axons however (80-85%), project down nerves which innervate ventral and anterior parts of the head-foot, the neck and the mantle. Dark Green Cell axons can be found in small nerves throughout these areas, and may terminate in a find plexus of axons on the surfaces of the nerves. Since previous experimental work has shown that the Dark Green Cells are involved in osmotic or ionic regulation, these results suggest that the target organ of the Dark Green Cells may be the skin. Yellow Cells occur both within and outside the c.n.s. They are usually monopolar, but can be bipolar. They have several axons which normally arise separately from a single pole of the cell body, or close to it. One or more processes leave the cell proximal to the point where separate axons arise, and may run unbranched for some distance through neuropile before terminating in fine brances and blobs of various sizes. These branches may release hormone inside the c.n.s. Yellow-green Cells are mono-, bi- or multi-polar, and like the Yellow Cells are found both within and outside the c.n.s. Some Yellow-green Cells, though not all, have projections which terminate in neuropile in fine branches and blobs. Yellow-green Cell bodies which occur in nerves can project back along the nerve into the c.n.s. The axons of Yellow Cells and Yellow-green Cells project to release sites in various ways. Some project into the connective tissue shealth of the c.n.s., which serves as a neurohaemal organ, either directly through the surface of a ganglion, or from the pleuro-cerebral or pleuro-parietal connectives. Other axons leave the c.n.s. via nerves leaving the left and right parietal and visceral ganglia; projections into the intestinal, anal, and internal right parietal nerves being most numerous. Axons which may be from either, or both Yellow Cells and Yellow-green Cells, can be found along the entire unbranched lengths of these nerves, and in subsequent branches which innervate organs lying in the anterior turn of the shell. All of these orgnas are closely associated with the lung cavity...

Animals↗

PubMed1979

The fate of acephate and carbaryl in water.

Acephate was resistent to hydrolysis in distilled, buffered water at pH 4.0 to 6.9, but not at pH 8.2, held for 20 days at 20 or 30 degrees C. The maximum conversion to methamidophos was 4.5% of the added acephate at pH 8.2 and 20 degrees C. The persistence of acephate in two natural waters, held at 9 degrees C for up to 42 and 50 days varied: 80% were recovered from pond water after 42 days, and 45% from creek water after 50 days. Rates of acephate degradation increased greatly when treated water samples were incubated in the presence of sediments, but not if water and sediment were autoclaved prior to treatment and incubation. The greatest conversion to methamidophos, 1.3% of the added acephate, had occurred after 42 days in pond water without sediment. Under the same conditions, carbaryl was less persistent than acephate in the natural waters: 18 to 20% were recovered from pond water after 42 days, and 37 to 40% from creek water after 50 days. The presence of sediment did not affect its degradation significantly. But more than 55% were recovered after 50 days if water and sediment were autoclaved prior to treatment and incubation. Neither acephate, methamidophos, nor carbaryl could be shown to escape from water into the atmosphere.

British Columbia↗

PubMed2026

A species-discriminatory aerA TaqMan qPCR assay for rapid quantification of Aeromonas veronii in fish tissues and aquaculture water.

Aeromonas veronii is a major bacterial pathogen in freshwater aquaculture, yet rapid species-level quantification remains challenging within the genetically complex genus Aeromonas. We developed a singleplex hydrolysis-probe (TaqMan) quantitative PCR (qPCR) assay targeting an A. veronii-discriminatory region of the aerolysin gene (aerA) and validated it according to MIQE recommendations. Plasmid standards gave a linear range of 2 to 2 × 106 copies/reaction (R2 = 0.9962) with 100.5% amplification efficiency. The endpoint limit of detection was 2 copies per reaction, and 20 copies per reaction was set as the practical reporting limit based on reproducible detection and low intra- and inter-assay variation. Analytical specificity was evaluated with genomic DNA from an 18-strain panel, with reproducible amplification observed only for A. veronii. The assay was further tested in 55 fish-tissue and 11 aquaculture-water DNA extracts. NH8B-1D2 sample-process monitoring was used for matrix-level recovery correction, and tissue and water extraction blanks were undetermined. The aerA target was detected in all tested gill, stomach/intestine, spleen, kidney/head kidney, pond-water filter and Xiamen seawater filter extracts, and in 10/11 liver extracts. Median NH8B-corrected loads were highest in gill among tissues and higher in pond-water filters than in Xiamen seawater filters. A separate Vibrio harveyi inhibition-check assay indicated no obvious amplification-stage inhibition. This assay supports rapid quantification of aerA-positive A. veronii in fish and aquaculture-water matrices.

Animals↗

PubMed2024

Water source, latrine type, and rainfall are associated with detection of non-optimal and enteric bacteria in the vaginal microbiome: a prospective observational cohort study nested within a cluster randomized controlled trial.

BACKGROUND: Less than one-third of sub-Saharan Africans have access to improved water sources. In US, Indian, and African studies, Bacterial vaginosis (BV) is increased among women with poor water, sanitation, and hygiene (WASH). We examined water source, sanitation (latrine type), and rainfall in relation to the vaginal microbiome (VMB). METHODS: In a cluster randomized controlled trial of menstrual cups and cash transfer, we measured the impact of cups on VMB via 16S rRNA gene amplicon sequencing in a subset of 436 adolescent girls. We analyzed how self-reported water source and latrine type at home related to VMB over 18-months, examining community state type I (CST-I, L. crispatus dominant) vs. other CST; alpha diversity; targeted taxa (coliform and other water-related pathogens); and non-targeted taxa via machine learning approaches. Mixed effects multivariable longitudinal models were adjusted for intervention arm, age, socioeconomic status, sexual activity, and cluster-level school WASH and rainfall (in millimeters). RESULTS: Adjusting for all covariates in all models: (1) the odds of CST-I were increased among participants with piped water (vs. pond), and decreased with traditional pit latrine vs. flush toilet. (2) Alpha diversity varied by water source and latrine type without consistent trends. (3) Coliform bacteria relative abundance (RA) was higher among participants with traditional pit or ventilated improved pit latrines vs. flush toilet, and higher among participants relying on stream vs. pond water. Streptococcus agalactiae RA was higher among participants with non-flush toilets, while Bacteroides fragilis RA was lower with non-flush toilets. (4) Key taxa from non-targeted analyses associated with water source and latrine type included typical vaginal bacteria, opportunistic pathogens, and urinary tract pathobionts. (6) Increased rainfall was associated with decreased odds of CST-I. TRIAL REGISTRATION: ClinicalTrials.gov NCT03051789, February 14, 2017.

Adolescent↗

PubMed2026

Genome-wide epigenomic atlas and multi-omics responses of Eriocheir sinensis to natural extreme heat.

BACKGROUND: Global climate warming has led to increasingly frequent and prolonged extreme summer heat events, posing severe environmental challenges to aquaculture systems. Extreme summer heat can disrupt the performance of pond-cultured ectotherms. The Chinese mitten crab (Eriocheir sinensis) is an economically important freshwater crustacean, but coordinated molecular differences following contrasting natural summers remain incompletely characterized. RESULTS: We performed a comprehensive multi-omics analysis integrating meteorological monitoring, mRNA/lncRNA transcriptomics, small-RNA profiling of miRNAs, DNA methylomics, and LC-MS metabolomics in E. sinensis populations collected from Yancheng, China, between 2020 and 2024. Across the ten farms, survival was significantly lower in 2024, whereas yield and the proportion of large individuals showed nonsignificant downward trends. Gene-set analyses showed negative enrichment of cellular heat-response, protein-folding, oxidative-phosphorylation, and mitochondrial ATP-production terms in the 2024 cohort at the time of sampling. The integrated transcript annotation contained 72,240 lncRNAs and 63,833 mRNAs, and CpG was the predominant methylation context. Differential methylation analysis identified 73 regions and 185 cytosines, with hypomethylated events predominating within the significant subset. Metabolomic profiles differed between annual cohorts and mapped to carbohydrate, lipid, and amino-acid pathways. Cross-omics integration prioritized eight candidate genes-ADCY9, UNC79, UBN1, IFT52, ACO2, LOC126986070, LOC127001126, and LOC126997895-and qPCR reproduced the reported directions of expression for selected RNAs. CONCLUSION: This study provides the first integrative multi-omics framework for understanding chronic heat adaptation in E. sinensis. By linking transcriptomic, epigenomic, and metabolic remodeling, we elucidate the molecular mechanisms underlying energy imbalance, epigenetic reprogramming, and immune dysregulation during prolonged thermal stress. These findings offer valuable insights and genomic resources for breeding heat-tolerant crab strains and improving aquaculture resilience under ongoing climate change.

DNA methylation↗

PubMed2026

Development and identification of KASP-SNP markers correlated with Aeromonas hydrophila resistance traits in blunt snout bream (Megalobrama amblycephala).

The blunt snout bream (Megalobrama amblycephala) is an economically important freshwater fish species. However, it is highly susceptible to Aeromonas hydrophila infection, especially in intensive pond aquaculture in China. Molecular marker-assisted selection provides an efficient approach for breeding disease-resistant varieties; however, the key genes or molecular markers linked to A. hydrophila resistance remain scarce in this species. A 436 differential SNP sites with disease-resistant were screened on basis of whole-genome resequencing. Then, a high-throughput genomic KASP genotyping technique was utilized to discover favorable genes and SNP sites associated with A. hydrophila resistance. A total of 46 KASP markers were successfully developed with an accuracy of 92 %. These markers were used to genotyping 120 blunt snout bream individuals. Through trait correlation analysis and general linear models (GLM), five SNPs significantly (P < 0.05) associated with resistance to A. hydrophila were identified and mapped to five candidate genes (btnl2, cfhr2, slc47a1, neu3, nlrp1). Survival rate of individuals carrying the dominant genotype demonstrated an average survival rate of 81.39 %, which represents a 69.35 % increase in comparison with that of 48 % in total population. This effect was validated in an external population of 100 fish. These findings identify key genetic markers associated with A. hydrophila resistance and provide a direction for elucidating the underlying molecular immune mechanisms, thus establishing a genetic foundation for future breeding strategies.

Cyprinidae↗

PubMed2026

Agricultural sprinkler irrigation systems as environmental reservoirs and airborne dissemination sources of Legionella pneumophila.

Sprinkler irrigation systems are critical for modern agriculture but represent largely unrecognized aquatic environments capable of sustaining opportunistic human pathogens. Among them, Legionella pneumophila is of particular concern due to its ability to colonize engineered water systems, persist under fluctuating environmental conditions, and be transmitted through aerosols. In this study, we conducted a comprehensive microbiological and genomic investigation of irrigation ponds and ditches in a rural area of north-east Spain where two zones were sampled. Metagenomic profiling revealed highly diverse microbial communities encompassing more than 20,000 species, including 21 airborne-transmissible bacterial pathogens of clinical relevance. Notably, L. pneumophila was detected in both zones, with a relative abundance of up to 4.6 %. Culture-based isolation confirmed the presence of L. pneumophila serogroup 1, Pontiac group, Benidorm subgroup, sequence type 15. Phylogenetic analysis demonstrated a close relationship between this environmental strain and clinical isolates obtained during a Legionnaires' disease outbreak occurred in 2015, which had remained without a confirmed environmental source. Meteorological data from the exposure period revealed wind conditions favouring long-distance aerosol dispersion from irrigated fields toward residential areas. Our findings provide evidence that irrigation infrastructures can act as environmental reservoirs and dissemination routes of L. pneumophila among other airborne pathogens. These results underscore the need to incorporate agricultural irrigation systems into routine environmental surveillance, outbreak investigations, and public health risk assessments.

Legionella pneumophila↗

PubMed2026

Evaluating sampling strategies for the detection of avian influenza viruses in the environment.

Highly pathogenic avian influenza (HPAI) viruses pose an increasing threat to wildlife, livestock and human health, underscoring the need for scalable and early-warning surveillance systems. Environmental RNA (eRNA) monitoring offers a non-invasive, cost-effective alternative to traditional host-based sampling by detecting viral genetic material shed into the environment. Despite its utility, the relative performance of different environmental sampling approaches for avian influenza virus (AIV) detection remains poorly resolved. Here, we conducted a longitudinal study with monthly sampling over approximately one year across two urban waterfowl ponds in Aotearoa New Zealand to evaluate four eRNA sampling strategies - fresh faeces, sediment, active-filtered water and passive-filtered water - for their ability to detect AIV. Using a combination of metagenomic sequencing and RT-qPCR, we show that all sample types can detect AIV, although detections were highly inconsistent across sampling methods, locations and time points. While metagenomic sequencing provided valuable genomic data, including subtype identification and phylogenetic context, RT-qPCR exhibited greater sensitivity, with active-filtered water yielding the highest detection rates, and is currently the more cost-effective approach for large-scale surveillance. Notably, AIV detections were asynchronous among sample types and frequently lacked temporal concordance, suggesting that environmental heterogeneity, RNA persistence, and methodological detection limits strongly influence surveillance outcomes. Despite these inconsistencies, phylogenetic analyses revealed that detected viruses belong to established Australasian lineages, highlighting the ability of environmental surveillance to capture ecologically relevant viral diversity. Our findings demonstrate that while eRNA-based surveillance holds substantial promise as a complementary tool for AIV monitoring, its effectiveness is highly dependent on the environmental sampling strategies and laboratory detection methods used.

Ducks↗

PubMed1978

Loss of carbofuran from rice paddy water: chemical and physical factors.

The loss of carbofuran was studied from rice paddy water treated with a granular formulation of the insecticide, and from ponds filled with drainage from the paddy. The average half-life (t 1/2) for carbofuran loss was 57 hr. Controlled experiments indicated that pH was the predominating factor governing carbofuran loss from water in the environment studied. The loss due to hydrolysis was over 700 times more rapid at pH (t 1/2 = 1.2 hr.) than at pH (t 1/2 = 864 hr.) in buffered deionized water. The average pH of the rice paddy was 8, but diurnal fluctuations of 7 to 9.5 are common in similar environments. Impurities in the water, sunlight, and temperature influence the rate of carbofuran loss but not nearly so much as pH. There was no evidence for significant loss due to evaporation or oxidation. The results have important implications for the duration of the insecticide's activity and the effect on fish within or downstream from treated paddies.

Carbofuran↗

PubMed2026

Genome-scale insights into metabolic streamlining and photosynthetic energy balance in the extremophile green alga Picocystis salinarum (Picocystophyceae, Chlorophyta).

Picocystis salinarum is an early-diverging chlorophyte and the sole described member of the Picocystophyceae, frequently dominating hypersaline and alkaline lakes despite extreme physicochemical constraints. To elucidate the genomic foundations of its ecological success, we generated a fully annotated, chromosome-scale nuclear genome assembly of the type strain originally isolated from a saline pond in San Francisco Bay. The 18.5-Mb genome comprises 30 chromosomal assemblies, exhibits clear diploidy, and contains multiple copies of intact Ty3/Gypsy and Ty1/Copia long terminal repeat retrotransposons encoding polyproteins with atypical accessory domains. Phylogenomic analyses reveal strong affinity with the Nephroselmidophyceae. Comparative analyses reveal extensive metabolic streamlining, including the absence of a queuosine salvage pathway, the 2-methylcitrate cycle, β-oxidation of propionate, and branched-chain amino acid catabolism, traits retained in several marine prasinophyte lineages. In contrast, the genome preserves multiple ancestral bacterial derived systems. Notably, P. salinarum features a complete chloroplast NADH dehydrogenase-like complex, including all membrane, electron binding, and assembly components, a configuration not previously reported in sequenced chlorophyte algae. This retention implies substantial capacity for cyclic electron flow and chlororespiration, processes expected to be critical in chronically low-light and chemically extreme environments. The genome further reveals a distinctive biochemical CO2-concentrating mechanism centered on plastid-targeted phosphoenolpyruvate carboxykinase, complete plastid peptidoglycan biosynthetic and remodeling pathways, and partial retention of lipid-A-related machinery. Conversely, P. salinarum lacks canonical non-photochemical quenching proteins while retaining xanthophyll-cycle enzymes that support slower photoprotective responses. Together, these features define a coordinated genomic architecture that underpins the specialization of P. salinarum to hypersaline, alkaline, and persistently low-light ecosystems.

3‐deoxy‐D‐manno‐octulo↗

PubMed1977

Growth characteristics of a new methylomonad.

A methylomonad culture was isolated from pond water and examined as a potential source of single-cell protein. A medium containing magnesium sulfate, ammonium hydroxide, sodium phosphate, tap water, and methanol supported the growth of the isolate. Optimal growth conditions in batch cultures for the organism were: temperature, 30 to 33 degrees C; pH 7.1; and phosphate concentration, 0.015 M. The minimum doubling time obtained was 1.6 h. The specific growth rate in batch culture was dependent on the methanol concentration, reaching a maximum around 0.2% (wt/vol). Growth inhibition was apparent above 0.3% (wt/vol), and growth was completely inhibited above 4.6% (wt/vol) methanol. Although the inhibitory effect of formaldehyde on the specific growth rate was much greater than that of formate, the organism utilized formaldehyde, but not formate, as a sole carbon and energy source in batch cultures. The isolate was identified primarily by its inability to utilize any carbon source other than methanol and formaldehyde for growth. Although it is capable of rapid growth on methanol, the organism showed a very weak catalase activity. The amino acid content of the cells compared favorably with the reference levels for the essential amino acids specific by the Food and Agricultural Organization of the United Nations.

Amino Acids↗

PubMed2026

Draft genome sequence of a novel hydrogenogenic CO-oxidizing bacterium that is phylogenetically closely related to the family Thermicanaceae.

An anaerobic, thermophilic hydrogenogenic carbon monoxide (CO)-oxidizing Bacillota bacterium, 3446A, was isolated from freshwater pond sediments in Kyoto, Japan. The 3.11-Mbp draft genome sequence (guanine-cytosine content, 50.4%) encodes CODH-ECH genes, consistent with hydrogenogenic CO oxidation. Phylogenomic analysis suggests that Bacillota bacterium 3446A represents a novel genus-level lineage within the family Thermicanaceae.

Thermicanaceae↗

PubMed1979

Utilization of seawater-urea as a culture medium for Spirulina maxima.

The possibilities of utilization of seawater enriched with ureas as the culture medium for a blue-green alga, Spirulina maxima, were investigated. Pretreatment by precipitation with NaHCO3 and (or) Na2CO3 was found essential to remove the excess amounts of Ca2+ and Mg2+ present in seawater prior to cultivation. A culture medium as good as the synthetic medium reported in the literature for the growth of S. maxima was obtained after treating seawater with NaHCO3 (19.2 g/L) at pH 9.2 and 35 degrees C for 2 h, filtering to remove precipitates, and enriching with K2HPO4 (0.5 g/L), NaNO3 (3.0 g/L), and FeSO4 (0.01 g/L). The same results were obtained by substituting a small amount (0.2 g/L or less) of either crystalline or polymerized urea for the NaNO3 in the above medium. Growth of S. maxima was inhibited at higher concentration of urea in the culture medium. The inhibition effect was due to the partial decomposition of urea into ammonia in alkali medium. Tests conducted on the 130-L cultivation open pond also confirmed that the seawater-urea medium supports growth of S. maxima as well as the best known synthetic medium.

Culture Media↗

PubMed2026

Cattle manure suppresses methane consumption and enhances denitrification-associated nitrous oxide production in farm dams.

BACKGROUND: Farm dams (or agricultural ponds) are often heavily polluted freshwater systems because of nutrient-rich manure entering the water through direct deposition and runoff. Accordingly, these systems have among the highest greenhouse gas emissions per area, accounting for 41% of global freshwater methane emissions. Sustainable management actions, such as limiting livestock access through fencing, can significantly reduce nutrient concentrations and greenhouse gas emissions. However, the microbes, processes, and factors controlling greenhouse gas cycling in these systems have not been described. Here, we systematically compared the composition, functions, and activities of the microbes in paired fenced and unfenced cattle farm dams in southeastern Australia. RESULTS: We found that in situ methane (CH4) and nitrous oxide (N2O) emissions were strongly reduced in fenced dams. Even though methanogen abundance was higher in fenced dams, fencing increased levels of aerobic methanotrophs, including two previously uncharacterised, metabolically flexible species profiled via metagenome-assembled genomes (MAGs). In contrast, we provide gene- and genome-centric evidence that N2O emissions are likely higher in unfenced dams due to increased production (via denitrification) rather than decreased consumption. Manure likely increases CH4 and N2O emissions primarily by driving nutrient-induced eutrophication and hypoxia that, respectively, stimulate denitrifiers and inhibit methanotrophs. However, we also provide evidence that manure-associated methanogens and bacteria occur in farm dams, where they potentially enhance emissions. CONCLUSIONS: Our findings highlight how anthropogenic activities such as livestock farming can impact microbial communities and biogeochemical cycling, thereby increasing greenhouse gas emissions from freshwater systems, and how simple management actions like fencing can mitigate such emissions. Video Abstract.

Animals↗