Changes In Communities Research Articles

Habitat type controls microarthropod community changes across a Magellanic sub-Antarctic elevation gradient

IntroductionElevation gradients are often used as a proxy for climate change as they allow comparisons of ecological responses over much larger temporal and spatial scales than is possible through experimental manipulations.MethodsHere, we tested how microarthropod communities (Collembola and Acari) are affected by climatic differences between sea level and 600 m a.s.l. on Navarino Island, in the Magellanic sub-Antarctic ecoregion of southern Chile (mean annual temperatures of 5.6 vs 3.1°C, respectively). We quantified microarthropod abundance, richness and community trait characteristics in dominant moss (Racomitrium lanuginosum and Polytrichum strictum) and lichen (Usnea trachycarpa, Pseudocyphellaria freycinetii and Stereocaulon alpinum) vegetation growing at both elevations. These moss and lichen genera are characterized by large morphological differences and allow testing of how habitat characteristics affect microarthropod community response across elevation gradients.ResultsCollembola and Acari community composition differed between the low and high elevation sites. Total abundance levels of Acari were maintained in each habitat across elevation, whereas Collembola richness strongly declined (50%) at high elevation in the moss habitats. Acari community differences across elevation were driven by relative abundance changes whereas the Collembola community lost species at higher elevation. An anticipated decline of smaller eudaphic Collembola at high elevation was only observed in the moss Racomitrium, reflecting potentially lower temperature buffering capacity and shelter options compared to Polytrichum. Lichens mostly supported larger epigeic species irrespective of elevation. There were no consistent patterns linking microarthropod communities with habitat water holding capacity or water loss rates across the studied habitats and elevation.DiscussionHabitat type and the genus of moss or lichen were associated with microarthropod community changes across elevation, including examples of declines, increases and no change. These findings highlight that community responses across gradients may not always relate to the generally hypothesized environmental variables (e.g. temperature variability) and that habitat characteristics should be taken into account when using elevation as a proxy for climate change.

Benthic response to the strong Silurian climatic fluctuations—implications from Gotland (Sweden)

Climatically the Silurian was a most unstable period, as it is shows several strong δ13C excursions, with the Lau excursion being the strongest short-lived positive δ13C excursion of the entire Phanerozoic. The causes of these excursions remain a topic of debate. In order to determine how benthic communities responded to these climatic perturbations, a microfacies analysis of carbonate rocks from the Silurian period (Late Telychian to the uppermost Ludfordian) of Gotland was conducted. The development of reefs was significantly enhanced during periods characterized by carbon isotope excursions, compared to time intervals without. In periods of elevated δ13C values (≥ 3 ‰) the abundance of bryozoans and microbes increases, and in some areas, they form reefs (bryostromatolites), while corals and stromatoporoids were the main reef builders in periods of lower isotope ratios (0–3 ‰). Furthermore, a significant increase of phosphatic components, gypsum pseudomorphs and the microproblematicum Palaeomicrocodium is observed in times of increased isotope ratios. A model is proposed that explains the changes in the benthic communities over time. It is based on previously published models and explains the geochemical processes from coastal areas to the open ocean. Changes are assumed from a humid climate in times without isotope excursions to an arid climate in times of isotope excursions. It emphasizes processes that may have led to the strong δ13C shifts during the Silurian period, and includes the phosphorus cycle in sea water as an important factor in the development of the benthic communities.

Structure and long-term changes of polychaete communities of the Varanger fjord in 2003 and 2019

Long-term changes in species composition, production indicators, and structure of polychaete communities for the period of 2003 and 2019 in the Russian part of the Varanger fjord (Barents Sea) were shown. The connection of such changes with climate factors and the influence of the red king crab are considered. The changes in species composition, structure, and production characteristics of polychaetes in the Russian part of the Varanger fjord (Barents Sea) in 2003 and 2019 are shown. The linkage between these changes and the climatic factor, as well as the influence of the introduced red king crab Paralithodes camtschaticus (Tilesius, 1815), is discussed. The results demonstrate an increase in the quantitative characteristics of polychaete Spiochaetopterus typicus M. Sars, 1856, indicating a decrease in pressure from the king crab on bottom communities. The biodiversity indices indicate the absence of negative changes in the settlements of polychaetes in the Varanger fjord during the studied period.

Changes in Cyanobacterial Phytoplankton Communities in Lake-Water Mesocosms Treated with Either Glucose or Hydrogen Peroxide.

When cyanobacterial phytoplankton form harmful cyanobacterial blooms (HCBs), the toxins they produce threaten freshwater ecosystems. Hydrogen peroxide is often used to control HCBs, but it is broadly toxic and dangerous to handle. Previously, we demonstrated that glucose addition to lake water could suppress the abundance of cyanobacteria. In this study, glucose was compared to hydrogen peroxide for the treatment of cyanobacterial phytoplankton communities. The six-week study was conducted in the large mesocosms facility at Grand Valley State University's Annis Water Resources Institute in Michigan. To 1000 L of Muskegon Lake water, glucose was added at either 150 mg or 30 mg glucose/L. Hydrogen peroxide was added at 3 mg/L to two 1000 L mesocosms. And two mesocosms were left untreated as controls. Triplicate 100 mL samples were collected weekly from each mesocosm, which were then filtered and frozen at -80 °C for 16S rRNA amplicon sequencing. The 16S rRNA amplicon sequencing results revealed that hydrogen peroxide treatment quickly reduced the relative abundance of the cyanobacteria compared to the control mesocosms, but the cyanobacteria population returned over the course of the 6-week study. On the other hand, both glucose concentrations caused a rapid proliferation of multiple low abundance proteobacterial and bacteroidotal taxa resulting in notable increases in taxonomic richness over the duration of the study and reducing the relative abundance of cyanobacteria. Although hydrogen peroxide quickly suppressed the cyanobacteria, the population later returned to near starting levels. The glucose suppressed the cyanobacterial phytoplankton apparently by promoting competitive heterotrophic bacteria.

Climate Warming and Mismanagement Drive the Shift of Fish Communities in the Wadi El-Rayan Arid Lakes

The Wadi El-Rayan lakes are important aquatic environments located at the border of the great North African Sahara. Quantifying the temporal changes in these lakes due to natural and/or anthropogenic stressors is critical when assessing potential impacts on aquatic ecosystem health and the sustainability of fisheries. To detect the changes in fish communities and their drivers, the landing composition of the Wadi El-Rayan lakes over the past 30 years was quantitatively analyzed. The areas of the lakes dramatically decreased from 110 km2 in 1991 to 73 km2 in 2019. The loss of the lake area was attributed to climate warming, where the evaporation rate exceeded the volume of recharge and the recharge decreased due to an increase in agriculture and aquaculture. The total landing significantly increased in the past three decades due to an increase in the fishing effort (number of licensed boats). Nile tilapia, mullet, and grass carp dominated the landings. The pelagic-to-demersal ratio indicated a shift in the fish community composition towards demersal species. This shift was attributed to an increase in the eutrophication level. The fish communities of the landing data were clustered into four distinct groups. These clusters were significantly differentiated (p < 0.001) in both a PERMANOVA test and a PCA plot. There was a gradual replacement of the dominant species among these clusters. The most recent cluster (2018–2019) was characterized by rare species dominating the community. This shift in species composition suggests that target taxa may have been overexploited. The total landing also decreased, which may have been a result of climate warming. Furthermore, the presence of alien and warm-water species significantly increased. The fish community structure and composition shift could be attributed to anthropogenic (mismanagement) and natural climatic changes (warming).

Detailed Insight into Gillnet Catches: Fish Directivity and Micro Distribution

Gillnets are widely used in research and commercial fishery activities. As passive gear, gillnets can be selective and dependent on the diel migration of fish. In areas with limited littoral extent, inshore–offshore migration may cause bias in the gillnet catch. Our hypothesis was that some factors, such as gillnet saturation, fish depletion, or chemical cues, could be the cause of the bias. We used a total of 66 CEN gillnets deployed at Římov Reservoir parallel to the shore at different positions of littoral-pelagic gradient. Individual fish direction was recorded from inshore, offshore, or unknown direction (i.e., entangled fish). A total of 5791 fishes from nine different species were caught. For most fish, it was possible to determine their directivity, and most fish were captured in littoral or first pelagic gillnets. Shallower and deeper benthic gillnets differed in their bleak (Alburnus alburnus) catch. No significant differences were found between fish directions. At the species level, only asp (Leuciscus aspius) and ruffe (Gymnocephalus cernua) showed differences between the captured directions in one case. The results support the assumption that gillnet capture is a random process that to a great extent is connected to random local movements. This is good news for fish monitoring projects. Sampling catch is likely to reflect true changes in the fish community, and not the effects of the deployment of the sampling gear. The experiment also showed that fish directivity statistics can be used for investigation of fish behavior and gear performance.

Fecal microbiome and functional prediction profiles of horses with and without crib-biting behavior: A comparative study

Crib-biting is a stereotyped oral behavior with poorly understood etiology and pathophysiology. The relationship between the gut microbiome and brain function has been described in behavioral disorders such as schizophrenia, depression and anxiety in humans. In horses, studies of behavioral problems and the microbiome are very limited. This study aimed to characterize the fecal microbiome and the predicted functional profile of horses with and without aerophagia. Fecal samples were collected from 12 Colombian Creole Horses of both sexes, divided into two groups: group 1, composed of six horses with crib-biting (3 females and 3 males), average body weight of 330 ± 10 kg, age of 7.0 ± 1.2 years and body condition score (BCS) of 5/9 ± 1 and group 2, consisting of six horses without crib-biting (3 females and 3 males), average body weight of 335 ± 5 kg, age 6.5 ± 1 years and BCS of 6/9 ± 1. From each horse in both groups fecal total DNA was obtained and 16S ribosomal RNA gene amplicons were sequenced to characterize the bacterial community structure. Community structure and differential abundance analyses revealed significant differences between the two conditions (p < 0.05). Specifically, the fecal microbiota at the family level in crib-biting horses, showing a decrease in Bacteroidales and an increase in Bacillota and Clostridia, differed from that of healthy horses without crib-biting, consistent with findings from previous studies. Furthermore, metagenome prediction suggests metabolic profile changes in bacterial communities between both conditions in horses. Further studies are required to validate the role of the microbiota-gut-brain axis in the etiology of crib-biting and other abnormal and stereotyped behaviors.

Changes in soil microbial community and function across stand age of Cryptomeria japonica var. sinensis plantations in subtropical China

Microbial communities are important influencing factors in soil biogeochemical cycling. Differences in stand age can affect microbial communities and functions by altering soil biochemical characteristics. Studying the changes in soil microbial communities and functions at different ages of Cryptomeria japonica var. sinensis can provide a theoretical basis for the scientific management of plantations. Therefore, we collected soil samples from different soil depths from 7- (7a), 13- (13a), 24- (24a), 33- (33a), and 53-year (53a) C. japonica var. sinensis plantations, to assess the differences in soil biochemical characteristics, soil bacterial and fungal communities, soil enzyme activity, and soil respiration rate. Results showed that as the stand age increases, the ACE and Shannon indices of fungal communities showed an initial increase followed by a decrease, whereas the Chao 1 index showed an increasing trend. The ACE and Shannon indices of bacterial communities did not change with stand age, but the Chao1 index decreased with an increase in stand age. In addition, the fungal ACE and Chao1 indices and bacterial Shannon index were higher at the 0–15 cm depth than at the 15–30 cm depth. Soil microbial community composition varied with stand age and soil depth, including Proteobacteria and Unclassified_k_Fungi relative abundances, and their functional groups' (nitrogen cycling-related bacteria, saprophytic fungi, pathogens, and ectomycorrhizal fungi) relative abundances. In addition, stand age will indirectly affect soil microbial function by influencing soil biochemical characteristics and microbial communities at the 0–15 cm depth, whereas at the 15–30 cm depth, there is no direct or indirect impact on the above indicators. In summary, significant variations exist in soil microbial communities and their functions across stand ages, and these differences will further vary between soil depths. Our research contributes to a better understanding of the impact of different ages of afforestation on soil biogeochemical cycling, providing valuable microbial information for the sustainable management of C. japonica var. sinensis forests in the future.

Interaction and dynamic changes of microbial communities and volatile flavor compounds during the fermentation process of coffee flower rice wine.

To develop a unique flavor of rice wine, coffee flowers (by-products of the coffee industry) were added because of their biologically active compounds that are conducive to health, and the fermentation parameters were optimized. In addition, the dynamic changes of microbial communities and volatile flavor compounds (VFCs) during the different fermentation stages were investigated. After the optimization of the fermentation parameters, a novel product, i.e., the coffee flower rice wine (CFRW), was obtained with a bright yellow transparent, fragrant, and harmonious aroma and mellow and refreshing taste by sensory evaluation, when 4.62% of the coffee flowers and 1.93% koji were added and fermented at 24.10°C for 3.88 days. The results showed that Lactococcus was the dominant bacteria, accounting for 87.0-95.7%, while Rhizopus and Cladosporium were the main fungi, accounting for 68.2% and 11.3% on average, respectively, in the fermentation process of the CFRW. Meanwhile, twenty-three VFCs were detected in the CFRW, which included three alcohols, six terpenes, ten esters, three aromatics, and one furan. The correlation analysis revealed that there were 16 significant positive correlations and 23 significant negative correlations between the bacterium and VFCs (|ρ| > 0.6, p < 0.05), while there were 12 significant positive correlations and one significant negative correlation between the fungi and VFCs (|ρ| > 0.6, p < 0.05). Furthermore, five VFCs, including linalool, geraniol, ethyl acetate, 1-hexanol, and 3-methyl-1-butanol, contributed vital flavors to the CFRW, and they were all significantly negatively correlated with the changes of Massilia and Acinetobacter (|ρ| > 0.6, p < 0.05). Moreover a significant positive correlation was found between the relative abundance of Lactococcus and the contents of 3-methyl-1-butanol and ethyl acetate (|ρ| > 0.6, p < 0.05). Therefore, this study provides a valuable theoretical basis for further improving the quality and production technology of CFRW.

Phytoplankton community composition as a driver of annual autochthonous organic carbon dynamics in the northern coastal Baltic Sea

Phytoplankton are the major primary producers in the pelagic system. They greatly influence biogeochemical cycles but little is known about the importance of shifting phytoplankton community composition for carbon dynamics. This study investigates the impact of seasonal changes in coastal phytoplankton communities on pelagic carbon fluxes. A field sampling campaign, covering an annual cycle in primary production, was conducted to assess the seasonal changes of phytoplankton communities and relevant organic carbon parameters in the coastal Baltic Sea. The monitoring frequency ranged from 1 to 3 wk, adapted to match the seasonal phytoplankton blooms. In addition, sediment traps were deployed to determine the particulate carbon and nutrient export to the seafloor in every season. We found that the phytoplankton biomass during the spring bloom was as high as 550 µg C l-1 and was dominated by diatom species (88% of total phytoplankton biomass). In comparison, the more species-rich summer bloom reached a combined maximum biomass of 236 µg C l-1. However, the highest export flux of particulate organic carbon was found in the middle of August (561 mmol C m-2 d-1) and, not as expected, around the spring bloom in May (226 mmol C m-2 d-1), suggesting a high potential for carbon recycling within the pelagic food web rather than being exported to the seafloor or advected laterally. Our study emphasizes the importance of keystone species and diversity for carbon transport processes in marine coastal ecosystems and highlights complex relationships between phytoplankton biomass production, community composition and carbon dynamics.

Chlorpyrifos modulates the mouse gut microbiota and metabolic activity

The organophosphate chlorpyrifos is a commonly used pesticide for fruits and vegetables despite its association with neurotoxicity in humans. While some studies suggest that organophosphates may impact the gut microbiota, no studies to date have investigated the direct effect of chlorpyrifos on the gut microbiota with doses that approximate environmentally relevant dietary concentrations (EPA chronic reference dose: 0.3 µg/kg/day in humans and EPA acute reference dose: 5 µg/kg/day in humans). Thus, we examined the influence of chlorpyrifos on the gut microbiota by assessment of bacterial physiology and metabolism using flow cytometry, 1H NMR-based metabolomics, and changes in the cecal microbiota community with 16S rRNA amplicon sequencing and analysis. Chlorpyrifos did not directly damage bacteria but rather perturbed bacterial metabolism. Chlorpyrifos exposure to bacteria increased the concentration of amino acids, carbohydrates, and nucleic acids. The relative abundances of Lactobacillus, Allobaculum, Roseburia, and Butyricicoccus increased after exposure to chlorpyrifos. Analyses of the 16S rRNA gene amplicon data predicted decreased amino acid biosynthesis and nucleic acid degradation and increased glycolysis which was supported by 1H NMR-based metabolomics. Collectively, these results demonstrate that environmentally relevant doses of chlorpyrifos can impact the metabolic activity of isolated gut microbes which may result in an imbalance in overall gut metabolic activity.

Effects of Phaffia rhodozyma on microbial community dynamics and tobacco quality during tobacco fermentation.

Carotenoids are important precursors of various aroma components in tobacco and play an important role in the sensory quality of tobacco. Phaffia rhodozyma is a species of Xanthophyllomyces capable of synthesizing a highly valuable carotenoid-astaxanthin, but has not yet been used in improving tobacco quality. The dynamic changes of microbial community and metabolites during tobacco fermentation were analyzed in combination with microbiome and metabolome, and the quality of tobacco after fermentation was evaluated by sensory scores. P. rhodozyma could grow and produce carotenoids in tobacco extract, with a maximum biomass of 6.50 g/L and a maximum carotenoid production of 36.13 mg/L at 100 g/L tobacco extract. Meanwhile, the correlation analysis combined with microbiome and metabolomics showed that P. rhodozyma was significantly positively correlated with 11 metabolites such as 6-hydroxyluteolin and quercetin. Furthermore, the contents of alcohols, ketones and esters, which were important aromatic components in fermented tobacco, reached 77.57 μg/g, 58.28 μg/g and 73.51 μg/g, increasing 37.39%, 265.39% and 266.27% compared to the control group, respectively. Therefore, the aroma and flavor, and taste scores of fermented tobacco increased by 0.5 and 1.0 points respectively. This study confirmed that P. rhodozyma fermentation could effectively improve the sensory evaluation of tobacco, and provided a novel microbial fermentation method to improve tobacco quality.

The influence of river basin nitrogen pollution sources and their transport on microbial community structure

The characterization of variations in riverine microbiota that stem from contaminant sources and transport modes is important for understanding biogeochemical processes. However, the association between complex anthropogenic nitrogen pollution and bacteria has not been extensively investigated owing to the difficulties faced while determining the distribution of nitrogen contaminants in watersheds. Here, we employed the Nitrogen and Oxygen Stable Isotope Tools alongside microbiological analysis to explore microbial characteristics and their responses to complex nitrogen pollution patterns. Significant changes in microbial communities were observed in watersheds with different complex nitrogen pollution sources migrating. Complex nitrogen sources were closely associated with microbiota. The main sources of nitrogen pollution in the dry season watershed were Manurc and Sewage (M&amp;amp;S, 54.2%). M&amp;amp;S exhibited reduced microbial diversity, high number of denitrification groups, and increased nitrogen cycling compared with others. However, Soil Nitrogen sources (SN, 59.3%) in the watershed during the wet season were the main contributors of nitrogen in the watershed. Eluviation allows SN to increased microbial community similarity, in addition to facilitating microbial immobilization processes. Overall, this study expands our knowledge regarding microbial biogeochemistry in catchments and beyond by linking specific nitrogen pollution scenarios to microorganisms.

Transcriptional Changes Underlying the Degradation of Plant Community in Alpine Meadow Under Seasonal Warming Impact.

Global warming is exhibiting a seasonal trend, while different seasons have different warming variations. However, the impact of seasonal warming on plants remains unclear. This study employed Open Top Chambers (OTCs) to simulate future seasonal warming scenarios in alpine meadow. The study examined plant community dynamics following long-term seasonal warming. The transcriptional and physiological responses of two dominant species (Kobresia pygmaea and Stipa purpurea) were examined. Results suggest that seasonal warming effects are correlated with both the duration of warming and the season which warming occurs. A long annual warming duration, especially growing season warming, made plants confront various stresses. K. pygmaea adopted a stress-avoidance strategy, showing a negative response, and leading to population decline or disappearance. This kind of dieback had also been observed in other Cyperaceae species. Meanwhile, due to positive responses, S. purpurea adopted a stress-tolerance strategy and overcame the impact of warming, partially gained the dominance over Cyperaceae species. Overall vegetation coverage and plant community diversity decreased over the years. These results reveal the impact of seasonal warming to plants, explaining the reasons for changes in plant communities under seasonal warming and providing new insights for future plant conservation under seasonal warming.

Carbon monoxide conversion by anaerobic microbiome in a thermophilic trickle bed reactor

Biomethanation offers a promising route for the valorization of synthesis gas, yet significant challenges arise from the limited conversion of carbon monoxide (CO). This study investigated the adaptation of an anaerobic microbiome in a continuous trickle bed reactor (TBR) with CO as the sole carbon and energy source. We evaluated reactor performance and microbial community changes under different CO loading rates and gas retention times (GRT). Optimal performance was achieved at a CO loading rate of 5.16 Nm³ m⁻³ d⁻¹ and a GRT of 60.6 min, resulting in average production rates of 0.99 Nm³ m⁻³ d⁻¹ for CH₄ and 2.55 Nm⁻³ m⁻³ d⁻¹ for CO₂, with an 88 % CO conversion rate. Microbial analysis indicated that the community was dominated by the genus Methanothermobacter, known for its ability to utilize CO as a sole substrate, followed by a co-dominance of syntrophic acetate-oxidizing bacteria Syntrophaceticus. This syntrophic relationship between Methanothermobacter and Syntrophaceticus is expected to be crucial for the efficient CO conversion process. Additionally, the study proposes a two-reactor system for converting synthesis gas to grid-quality methane.

A comparative analysis of eDNA metabarcoding and field surveys: Exploring freshwater plant communities in rivers

While environmental DNA (eDNA) metabarcoding holds promise as a holistic approach to assess vegetation changes and community composition across diverse spatial and temporal scales, systematic investigations of its efficacy compared to conventional field surveys remain scarce in the literature. The present study explores the differences in plant diversity recovered from field surveys and captured with a multi-marker eDNA metabarcoding approach (two nrDNA ITS1 and ITS2, and two cpDNA rbcL and trnL) from river water samples. The eDNA metabarcoding approach retrieved 46 aquatic plants (hydrophytes and helophytes) and 245 terrestrial plants, compared to 24 and 127 species identified from field surveys. On average, eDNA samples collected immediately downstream of the survey sites recovered 43 % and 39 % of the aquatic and terrestrial species observed, respectively. Discrepancies were explained by differences in taxonomic resolution, the stochasticity of the retrieval of rare and elusive species, and the presence of reference sequences. We found a significant positive correlation between spatial and community distances at scales ranging from 2 to 9 km and identified turnover as the driving force of these differences. Metabarcoding demonstrated sensitivity to community changes and both approaches converge on a similar community structure. Interestingly, eDNA samples collected immediately upstream of the survey sites exhibited significant species overlap with the downstream samples (c. 100 m apart). Overall, our results demonstrate that within-site species mismatches between the methods are nonnegligible, and they question the use of eDNA for generating complete species lists at scales comparable to our field surveys (< 100-m transects). However, with adequate sampling and a multi-marker metabarcoding approach, eDNA has the potential to approximate catchment gamma diversity with less sampling effort than conventional surveys.

Supplementation with heat-killed Akkermansia muciniphila EB-AMDK19 counteracts diet-induced overweight in beagles

ABSTRACT Obesity is a major health problem in dogs and is strongly associated with an increased risk of chronic inflammatory and metabolic diseases. The microaerophilic human gut bacterium Akkermansia muciniphila has been proposed as a potential preventive and therapeutic agent against obesity in both humans and mice; however, the protective effects of human-derived A. muciniphila against canine obesity remain unstudied. We previously demonstrated that the heat-killed A. muciniphila strain EB-AMDK19 (AMDK19-HK) isolated from the faeces of a healthy Korean exerts similar protective effects as the live bacterium in mice with high-fat-diet (HFD)-induced obesity. Here, we evaluated the effects of AMDK19-HK on body weight, body fat mass, haematological and biochemical parameters, and faecal microbiota composition in beagles fed an HFD for 12 weeks. AMDK19-HK supplementation effectively suppressed body weight increase, body fat deposition and serum triglyceride increase in the canine model; however, no significant changes in the overall haematological and biochemical parameters were observed, reflecting the direct anti-obesity effect of AMDK19-HK. Additionally, 16S rRNA gene sequencing revealed that AMDK19-HK supplementation induced significant changes in the faecal bacterial community, with an increased abundance of Firmicutes and a decreased abundance of Bacteroidota. These results suggest that AMDK19-HK can be used as a dietary supplement to counteract diet-induced overweight in dogs.

Decay kinetics of human-associated pathogens in the marine microcosms reveals their new dynamics and potential indicators in the coastal waters of northern China

Pathogens in coastal waters cause infectious diseases and endanger public sanitation safety in humans and animals worldwide. To avoid these risks, timely detection of human-associated pathogens in waters is crucial. In this study, the decay kinetics of the molecular markers for human-associated pathogens, including enteric bacteria (Escherichia coli, Enterococcus, and Bacteroides), non-enteric bacteria (Staphylococcus aureus), crAssphage, and polyomavirus, were monitored over time at different temperatures and background microbes in seawater microcosms. The results indicated that temperature and native marine microbes were the main influential factors in attenuating bacterial pathogens. Remarkably, the effect of native microorganisms was more evidentially striking. Furthermore, Enterococcus was a more reliable and suitable fecal indicator bacterium than E. coli for the marine environment. The decay of crAssphage was like that of polyomavirus, indicating that it may be a good indicator of enterovirus in seawater. More importantly, the 16S amplicon sequencing data highlighted the decay kinetics of multiple bacterial pathogens in parallel with the dynamic changes of the whole bacterial communities. This study provides valuable information for public health risk management and a new approach to understanding the fate of bacteria in the coastal environment.

Eucarid and Peracarid Fauna of the Valencia Seamount, a Deep-Isolated Seamount of the Western Mediterranean: Colonisation Capacity and Historical Changes

Seamounts can have a strong influence on the distribution and diversity of species, creating an oasis effect that may favour diversification. In order to assess how and to what extent supra- and epibenthic crustaceans can colonise these environments, the eucarid and peracarid fauna collected from the summit of the Valencia Seamount (VS), a small deep seamount (summit depth: 1056 m), rising from a depth of ca. 1850 m, in the oligotrophic Balearic Basin, was analysed. Based on a first sampling (beam trawls, plankton nets and stomach contents), and a faunal reconstruction from a sediment core (MC2, at 1151 m), the supra(epi)benthic crustaceans at the VS summit (to 1300 m) were composed of nine Eucarida and 25 Peracarida. Polycheles typhlops, Munida tenuimana, and Aristeus antennatus were the dominant species among eucarids. Among Peracarida the most abundant species were the Mysida Boreomysis arctica, the Amphipoda Rhachtropis caeca, and the Isopoda Munnopsurus atlanticus. Among Decapoda, a species with a wide amplitude in their depth distribution and small eggs (i.e., with planktotrophic larvae), showed a higher colonisation capacity. In the absence of larvae, the colonisation of peracarids depends on the amplitude of their depth distribution and only those species that reach the highest depths in the entire Balearic Basin, at least 1600–1800 m, were able to colonise the summit of VS. The natatory capacity of the species also has some influence and whole groups with low natatory capacity, such as the Desmosomatidae, were completely absent on the VS summit; however, they are distributed throughout the Balearic Basin to depths (up to about 1500 m) exceeding the depth of the seamount summit. Therefore, colonisation by peracarids must not have occurred by swimming through the entire water column, but by swimming along or just above the bottom. Remains of some suprabenthic species (mainly the isopod M. atlanticus) in MC2 and another core collected in NW Mallorca (MC3, 1114 m), i.e., out of the VS, showed how isopod diversity and size distribution changed historically. Also, after the 1960s, a decrease in primary production due to a decrease in rainfall and river runoff associated with river damming could have reduced the abundance of M. atlanticus. These types of historical studies can be useful in interpreting long-term changes in deep-sea communities and optimising the management of these vulnerable areas.

Effects of long-term continuous cultivation on the structure and function of soil bacterial and fungal communities of Fritillaria Cirrhosa on the Qinghai-Tibetan Plateau.

Fritillaria cirrhosa, an endangered medicinal plant in the Qinghai-Tibet Plateau, is facing resource scarcity. Artificial cultivation has been employed to address this issue, but problems related to continuous cultivation hinder successful transplantation. Imbalanced microbial communities are considered a potential cause, yet the overall changes in the microbial community under continuous cropping systems remain poorly understood. Here, we investigated the effects of varying durations of continuous cropping on the bacterial and fungal communities, as well as enzymatic activities, in the rhizospheric soil of F. cirrhosa. Our findings revealed that continuous cropping of F. cirrhosa resulted in soil acidification, nutrient imbalances, and increased enzyme activity. Specifically, after 10 years of continuous cropping, there was a notable shift in the abundance and diversity (e.g., Chao1 index) of soil bacteria and fungi. Moreover, microbial composition analyses revealed a significant accumulation of harmful microorganisms associated with soil-borne diseases (e.g., Luteimonas, Parastagonospora, Pseudogymnoascus) in successively cropped soils, in contrast to the significant reduction of beneficial microorganisms (e.g., Sphingomonas, Lysobacter, Cladosporium) that promote plant growth and development and protect against diseases such as Fusarium sp.These changes led to decreased connectivity and stability within the soil microbial community. Structural equation modeling and redundancy analysis revealed that alkaline hydrolytic nitrogen and available phosphorus directly influenced soil pH, which was identified as the primary driver of soil microbial community changes and subsequently contributed to soil health deterioration. Overall, our results highlight that soil acidification and imbalanced rhizosphere microbial communities are the primary challenges associated with continuous cropping of F. cirrhosa. These findings establish a theoretical foundation for standardized cultivation practices of F. cirrhosa and the bioremediation of continuously cultivated soils.