Shifts In Composition Research Articles

Holocene palaeoecological changes in a transitional climate zone of western-central Mexico: The pollen and non-pollen palynomorphs record

The Alberca de Tacámbaro (AT) is located at a transitional zone between tropical and temperate climates at the core of the North American Monsoon area. This location features a mosaic vegetation comprising pine-oak forests and tropical dry forests. Currently there is no information regarding the dynamics or evolution during the Holocene of these vegetation types. The palynological record of the last 9400 years BP preserved in the lacustrine sequence of the AT was used to document changes in the composition of terrestrial and aquatic communities, evenness, and rate of change. Pinus and Quercus forests dominated the terrestrial palynological record, but mesophytic forests were also recorded throughout the sequence. Four tropical dry forest taxa assemblage expansions were identified at 9200 to 8420 yr BP; 5900 to 5230 yr BP; 3100 to 2800 yr BP; and 2300 to 2000 yr BP. These phases correlated with times of reduced North American Monsoon intensity, suggesting that these communities thrived during drought periods. Variations in non-pollen palynomorphs were synchronic with the lithostratigraphic, geochemical data as well as with the terrestrial changes. During the Meghalayan, compositional shifts in the vegetation and increases in the herbaceous elements indicated human impact, while aquatic taxa, suggested eutrophic and warmer conditions in the lake. By examining the history of this vegetation mosaic, the data on temporal vegetation dynamics during the Holocene offered clues about the response to ongoing global warming and how climate change will likely shape plant communities in western-central Mexico.

Oral microbiocenosis state under different approaches of replacing dental crown defects

Dental caries is one of the most common health problems. The aim of the research was to study the spectrum of microbiota, which is part of the dental biofilm, and its biological properties. The study involved 90 participants of the study group and 20 of the control group. Dental plaque and saliva were used as principal clinical specimens. The main research method was bacteriological. All samples from study participants were positive for microbiota. At the initial collection of material, 395 unique isolates were obtained: 338 from patients with caries and 57 from healthy volunteers. The microbiocenosis of the oral cavity associated with the development of caries contained such eudodominants as Streptococcus mutans, Peptostreptococcus spp., Fusobacterium spp., Prevotella spp. and dominants Streptococcus pyogenes, Enterobacterales, Prevotella spp. and Candida albicans. In contrast the eudominants of the healthy oral cavity were microorganisms with known commensal properties, in particular Streptococcus salivarius, Aerococcus viridans, Veillonella spp. After the dental treatment, significant shifts in the taxonomic composition of the dental biofilm were observed. Therefore, the composition of the oral cavity microbiocenosis in participants who underwent restoration of the dental crown defects with zirconium inserts approached patients to the healthy cohort participants. The eudodominants of the oral microbiocenosis of the participants who underwent direct restoration were S. mitis, Peptostreptococcus spp. and Veillonella spp. In zirconium restoration, the commensals S. salivarius and A. viridans were eudodominants. The obtained isolates of opportunists possessed high virulence properties. Streptococcus spp. cultures were sensitive to norfloxacin screening in only 28.6% of cases. Among cultures of the genus Staphylococcus, 23.8% were methicillin resistant. Representatives of Enterobacterales had chemotherapeutic sensitivity that varied significantly depending on the group of antimicrobial agents. Using disks with phenylboronic acid, ethylenediaminetetraacetic acid and cloxacillin, it was established that Klebsiella spp. were producers of class A carbapenemases (n=3) and contained AmpC (n=3). Carbapenemases were also produced by at least 65.2% of the studied cultures of non-fermenting gram-negative microorganisms. In our study, all obtained isolates were also endowed with the ability to form a biofilm. Therefore, microbiological research in dentistry should be considered as one of the objective methods for assessment of health of the oral cavity and will also have advantages in choosing a method of correcting defects of dental crown parts and in some cases, making an informed decision about the prescription of antimicrobial treatment.

Slow post-fire carbon balance recovery despite increased net uptake rates in Alaskan tundra

Abstract Increasing wildfire occurrence and intensity have immediate effects on northern ecosystems due to combustion of aboveground vegetation and belowground soil organic matter. These immediate impacts have indirect and longer term effects, including deepening of the active layer, changes in soil decomposition rates, and shifts in plant community composition. Despite the increasing fire impacts across the tundra region, the implications of wildfire on ecosystem carbon balance are not well understood. Using paired eddy covariance towers in unburned and burned tundra, we examined the effects of a 2015 wildfire on carbon dioxide and methane fluxes in a wetland tundra ecosystem in the Yukon-Kuskokwim Delta, Alaska, from 2020 to 2022. Wildfire increased the amplitude and variability of carbon uptake and release on seasonal and annual timescales and increased the temperature sensitivity of soil respiration. Seven years post fire, there was annual net uptake in both unburned and burned tundra based on net ecosystem exchange, with the sink strength of burned tundra exceeding that of the unburned tundra by 1.18 to 1.64 times. However, when considering emissions, it would take approximately 86 years to recover the carbon lost from the wildfire itself. Soil moisture was a dominant driver of fluxes and positively associated with higher rates of carbon dioxide uptake and release and methane release. This study underscores the importance of understanding the effects of wildfire-induced shifts on tundra carbon cycling, allowing better predictions of long-term landscape-scale climate feedbacks as the climate continues to warm.

Rapid shifts in grassland communities driven by climate change.

Many terrestrial plant communities, especially forests, have been shown to lag in response to rapid climate change. Grassland communities may respond more quickly to novel climates, as they consist mostly of short-lived species, which are directly exposed to macroclimate change. Here we report the rapid response of grassland communities to climate change in the California Floristic Province. We estimated 349 vascular plant species' climatic niches from 829,337 occurrence records, compiled 15 long-term community composition datasets from 12 observational studies and 3 global change experiments, and analysed community compositional shifts in the climate niche space. We show that communities experienced significant shifts towards species associated with warmer and drier locations at rates of 0.0216 ± 0.00592 °C yr-1 (mean ± s.e.) and -3.04 ± 0.742 mm yr-1, and these changes occurred at a pace similar to that of climate warming and drying. These directional shifts were consistent across observations and experiments. Our findings contrast with the lagged responses observed in communities dominated by long-lived plants and suggest greater biodiversity changes than expected in the near future.

Lethal disruption of the bacterial gut community in Eastern subterranean termite caused by boric acid.

The Eastern subterranean termite, Reticulitermes flavipes (Kollar) (Blattodea: Rhinotermitidae), is a significant pest, causing extensive damage to structures that amount to substantial economic losses. Boric acid is widely used for wood preservation due to its stability and broad-spectrum insecticidal properties, yet its impact on termite gut microbiomes and the implications of such effects remain understudied. Our study evaluates the dose-dependent mortality of R. flavipes upon being provided boric acid treated filter papers and investigates the resulting dysbiosis within the termite gut microbiome. Consistent with reports from other insects, mortality increased in a dose-dependent manner, with the highest boric acid concentration (203.7 µg/cm2 of filter paper) significantly reducing termite survival. 16S rRNA gene sequencing of the gut bacterial microbiome revealed notable shifts in composition, indicating boric acid-induced dysbiosis. Aside from an overall decrease in bacterial diversity, the relative abundance of some symbionts essential for termite nutrition decreased in response to higher boric acid concentrations, while several opportunistic pathogens increased. Our findings extend the understanding of boric acid's mode of action in termites, emphasizing its ability to significantly modulate the bacterial symbiont community, which can have dire effects on termite biology. Considering its ability to protect wood from further termite consumption, our study supports the continued use of boric acid and related compounds for termite-resistant treatments for wood.

The antidepressant effect of Komagataella pastoris KM 71 H in maternal separation mice model mediated by the microbiota-gut-brain axis

BackgroundThe intestinal microbiota plays a fundamental role in maintaining host health, especially during childhood, a critical period for its establishment. Early life stress can lead to shifts in gut microbiota composition, thus increasing the risk of major depressive disorder (MDD) in adulthood. The supplementation with probiotics restores intestinal permeability and the health of gut microbial communities, therefore being potential study targets for the treatment of MDD. In this sense, the yeast Komagataella pastoris was reported as a promising probiotic with antidepressant effect. MethodsHence, the present study aims to investigate this effect in mice submitted to maternal separation (MS) 3 h per day from PND2 to PND14. Adult mice and mothers were treated with K. pastoris KM71H (8 log UFC.g−1/per animal, i.g.) or PBS (500 µl, i.g.) for 14 days. After behavioral tests, the animals were euthanized, followed by hippocampi and intestines removal for biochemical analysis. ResultsOn behavioral tests, K. pastoris KM71H treatment reduced the immobility time in TST of adult mice and increased the grooming activity in splash test of adult mice and mothers induced by MS. The probiotic treatment restored plasma corticosterone levels and glucocorticoid receptor expression in hippocampi, alongside nitrate/nitrite levels and superoxide dismutase activity in intestine, in addition to reducing reactive species levels in both structures. Moreover, it also normalized the fecal pH and water content of feces. ConclusionThus, we conclude that K. pastoris KM71H is a promising therapeutic strategy for the treatment of MDD.

(Poly)phenol-rich grape and blueberry extract prevents LPS-induced disruption of the blood-brain barrier through the modulation of the gut microbiota-derived uremic toxins

The dynamic protective capacity of (poly)phenols, attributed to their potent antioxidant and anti-inflammatory properties, has been consistently reported. Due to their capacity to alter gut microbiome composition, further actions of (poly)phenols may be exerted through the modulation of the microbiota-gut-brain axis. However, the underlying mechanisms remain poorly defined. Here, we investigated the protective effect of a (poly)phenol-rich grape and blueberry extract (Memophenol™), on the microbiota-gut-brain axis in a model of chronic low-grade inflammation (0.5 mg/kg/wk lipopolysaccharide (LPS) for 8 weeks). Dietary supplementation of male C57BL/6 J mice with Memophenol™ prevented LPS-induced increases in the microbe-derived uremia-associated molecules, indoxyl sulfate (IS) and trimethylamine N-oxide (TMAO). These changes coincided with shifts in gut microbiome composition, notably Romboutsia and Desulfovibrio abundance, respectively. In the brain, LPS exposure disrupted the marginal localisation of the endothelial tight junction ZO-1 and downregulated ZO-1 mRNA expression to an extent closely correlated with TMAO and IS levels; a process prevented by Memophenol™ intake. Hippocampal mRNA sequencing analysis revealed significant downregulation in regulatory pathways of neurodegeneration with Memophenol™ intake. These findings may indicate a novel protective role of the (poly)phenol-rich grape and blueberry extract on the endothelial tight junction component ZO-1, acting through modulation of gut microbial metabolism.

The Gut Microbiome and Lignocellulose Digestion in Constrictotermes cyphergaster (Termitidae: Nasutitermitinae): A Termite Incorporating Lichen into Its Diet

Lichen-feeding termites occupy a distinctive ecological niche. This feeding behavior underscores a complex interplay between the termites’ digestive abilities and the biochemical properties of lichens, known for their resilience and production of secondary metabolites. Understanding the dietary preferences and digestive mechanisms of these termites offers insights into their ecological roles and the evolutionary adaptations that enable them to exploit such a specialized food source. We conducted experiments with Constrictotermes cyphergaster, feeding it with different combinations of its natural food sources: wood bark and lichen from host trees. Gut microbial communities were analyzed through 16S rRNA sequencing and shotgun metagenomics. Our results revealed that a diet containing lichens induces a shift in microbiota composition and increases the abundance of genes encoding an AA3 enzyme with a role in lignin digestion. This study emphasizes the potential role of lichens in enhancing the digestive capabilities of termites, highlighting the intricate relationships between diet, gut microbiota, and enzymatic activity in Termitidae.

The Composition and Function of Intestinal Microbiota Were Altered in Farmed Bullfrog Tadpoles (Aquarana catesbeiana) during Metamorphosis

The bullfrog Aquarana catesbeiana is one of the main farmed frog species in China, with a low overall survival of farmed bullfrogs from hatching to harvest since bullfrog tadpoles are fragile during the metamorphosis period. The intestinal bacterial community can play crucial roles in animal development; however, little is known about the alteration of the gut microbial community of A. catesbeiana during metamorphosis. The present study used 16S rRNA amplicon sequencing to investigate the intestinal bacterial community in A. catesbeiana at four distinct developmental stages. Moreover, we determined the bullfrog’s body morphological parameters and the intestine histology at different developmental stages. The results showed a reduction in the total length and snout–vent length of A. catesbeiana during metamorphosis. The intestinal microbial composition of A. catesbeiana exhibited variation throughout the process of metamorphosis. The terrestrial stage showed shifts in the bacterial composition compared to the aquatic stages, including a reduction in Bacteroidetes and an increase in Firmicutes. Furthermore, the presence of Prevotella, Bifidobacterium, Leucobacter, Corynebacterium, Bulleidia, Dorea, Robinsoniella, and Clostridium in A. catesbeiana metamorphosis appears to be mainly related to the host’s epithelial cells’ height and total body mass. The results indicated that the intestinal microbial composition changed with the bullfrog–tadpole metamorphosis. The genera of Prevotella, Bifidobacterium, Leucobacter, Corynebacterium, Bulleidia, Dorea, Robinsoniella, and Clostridium might be potential probiotics.

7143 Near Term Cardiometabolic Outcomes in Transgender Boys and Men in the First Year of Gender-Affirming Testosterone Therapy

Abstract Disclosure: J. Dey: None. M. Widlansky: None. S. Cabrera: None. Background: Gender affirming testosterone (T) therapy is used to masculinize transgender adolescent men (TMs), resulting in elevated T and suppressed estradiol (E2). In cis-females, hypoestrogenism reduces vaso-protective E2-mediated estrogen receptor expression, decreasing nitric oxide vasodilation and increasing susceptibility to future vascular complications. Whether T promotes similar changes in TMs remains poorly understood. Methods: A longitudinal observational study is conducted in TMs aged 12-30yrs over the 1st yr of T, with visits at baseline (BL; pre-T), 6mo, and 1yr, compared to cis-males (CMs) with endogenous T. Primary outcome is change in brachial artery flow-mediated dilation (FMD%), an in vivo measure of vascular endothelial health, after 1yr of T. To detect a significant relative change in FMD%, 60 participants are needed (40 TMs, 20 CMs). Metabolic profile is assessed by fasting lipids, glucose, and insulin. Body composition is assessed by BMI and DEXA. Differences in mean values between and within a cohort were analyzed using the unpaired two-tailed T-test assuming unequal and equal variances, respectively. Results: To date, 51 participants are enrolled; the 21 participants who fully completed the study are included here (13 TMs, 8 CMs). At BL, TMs were post-menarchal with a mean age of 15.6yrs, ht 162.6cm, and BMI z-score 0.47. At BL, 46% were on progestin-only menstrual suppression. CMs had a mean age of 18.4yrs, ht 170.7cm, and BMI z-score 0.13. Cohorts were similar for age, height, and BMI.At BL, FMD% was higher in TMs than CMs (8.2 vs 4.6, p=0.01) but not at 1yr (6.9 vs 6.2, p=0.6). FMD% did not change in TMs receiving T over 1yr (8.2 vs 6.9, p=0.3). At BL, the brachial artery resting diameter (mm) was lower in TMs than CMs (2.6 vs 3.5, p<0.01) and remained such at 1-yr. Resting diameter increased in TMs over 1yr of T (2.6 vs 3.1, p<0.01) but not in CMs. There were no differences in resting or hyperemic flow velocity, or FMD (mm) between or within groups. At BL, % lean body mass (%LBM) was lower in TMs than CMs (60 vs 72, p<0.01) and estimated percent visceral adiposity tissue (%VAT) was higher (26 vs 14, p<0.01). In TMs, %LBM increased (60 vs 66, p <0.01) and %VAT decreased (26 vs 21, p<0.01) over 1yr of T, such that TMs and CMs were similar at 1yr. At BL, TMs had lower T but similar E2 (46 vs 27 pg/mL, p=0.2) to CMs. At 1-yr, TMs and CMs had similar T (556 vs 574 ng/dL, p=0.9) and E2 (52 vs 29, p=0.1). In TMs, T did not change E2. Lipid and glycemic indices did not change over 1yr in TMs. Conclusion: Initial analyses suggest that T does not affect FMD; however, FMD% interpretation is confounded by the small number of participants, progestins at BL in TMs, and the lower resting brachial artery diameter in TMs. The stable E2 in TMs on T may explain the stable FMD%. Overall, our findings suggest T results in relative stability of vascular and metabolic function and a beneficial shift in body composition in TMs. Presentation: 6/2/2024

Influence of climate, weather and floral associations on pollinator community composition across an elevational gradient

Insect pollinators, which are ectothermic, are especially sensitive to abiotic conditions, which often drive predictable patterns of pollinator species turnover along environmental gradients. However, pollinator activity is also reliant on suitable biotic conditions, such as the presence of host plants. High‐elevation environments provide a useful setting to examine the relative contribution of abiotic and biotic factors in shaping species interactions as they are often characterised by strong environmental gradients over short geographic distances. Here, we examined pollination interaction networks across an elevational gradient from 930–2000 m a.s.l. in southern Australia, to determine the underlying patterns of pollinator activity and their interactions with flowers. Interaction frequency of Diptera increased at high elevations, while interaction frequency of Hymenoptera and Coleoptera decreased. We provide evidence that this elevational pattern of activity is partly driven by floral associations, with interactions dominated by Hymenoptera‐attracting plant families at lower elevations (Proteaceae, Fabaceae) and a Diptera‐attracting family at high elevation (Asteraceae). Pollinator activity was also influenced by weather conditions, with reduced activity for all three orders at lower temperatures, and Diptera active across the broadest range of temperature, humidity and wind conditions. We suggest that changes across elevation gradients in pollinator community composition are driven by both direct responses to abiotic conditions such as temperature, as well as the elevational distribution patterns of associated flowering plants. Despite these distinct shifts in composition of the pollinator assemblage with elevation, pollination network structure was stable across the elevational gradient, with moderate levels of specialisation and low levels of connectance and nestedness present across the gradient. By considering both abiotic conditions and biotic processes, our results provide insight for predicting the impacts of upslope vegetation shifts on pollinator communities in the face of climate change.

Macroinvertebrate Community Responses to Disturbance in a Fragmented River With Contrasting Legacies of Alteration

ABSTRACTFlow is a critical factor determining the riverine ecosystem structure and function. Widespread hydrologic alteration, however, has impacted the ecological integrity of rivers in ways that are not well understood, including responses of biological communities to increasingly frequent and severe climatic disturbances. Our study compared the responses of invertebrate communities on woody debris to large flooding and extreme drought in two highly contrasting segments of an impaired low‐gradient river. The upstream segment, which according to previous research has higher α‐diversity and production of large‐bodied and sensitive invertebrates, maintained higher flows and longitudinal connectivity throughout the 4‐year study. Communities in this upper segment resembled one another among sites (lower spatial turnover) but experienced greater temporal shifts in composition associated with hydrological disturbances. Conversely, invertebrate communities in the highly altered downstream segment, which is impaired by reduced flow, sedimentation, and hypoxia, were composed of smaller‐bodied and pollution‐tolerant taxa with lower α‐diversity. Unlike the upper segment, communities were patchily distributed among sites (higher spatial turnover), which made it more difficult to detect system‐wide temporal variation in composition throughout the study. Our study underscores the benefit of including measures of connectivity and spatial heterogeneity when assessing the ecological integrity of lotic systems. Understanding the system‐wide response to disturbances across longer time frames can help better predict and mitigate the impacts of climate change on ecosystem integrity in degraded rivers.

Combined effect of refrigerant amount reduction and composition change on heat pump system performance during refrigerant mixture leakage

The natural refrigerants and hydrofluoroolefins (HFOs), which are proposed as alternatives to traditional refrigerants, have weaknesses in terms of flammability, cost, or system performance. As a solution, refrigerant mixtures offer the advantage of variable thermodynamic properties, but their main drawback is the composition change caused by the refrigerant leakage. This study analyzes the performance change during the leakage process, considering the combined effect of refrigerant amount reduction and composition shift. A mixture of R32/R1234yf with an initial composition of 20/80 wt% was utilized as a working fluid, and four leakage scenarios were employed: a vapor or liquid leak occurring during winter at −10 °C or summer at 30 °C. The composition change during the leakage was calculated by the simulation model, and then experiments were conducted to measure the performance with the calculated composition. The simulation results show that the vapor leak in winter leads to the most significant composition change of 7.8%p, when 57.1% of the initial charge escapes from the system. From the experimental results, the coefficient of performance (COP) exhibits the lowest value after the liquid leak in summer due to the increased mass fraction of R32, with a decrease of 89.5% compared to the initial COP. This degradation consists of 80.2%p due to refrigerant amount reduction and 9.3%p due to the composition shift. By considering the effects of both refrigerant amount and composition, this study provides a comprehensive analysis of the performance changes in a heat pump system during refrigerant mixture leakage.

Hydrodynamics Mediates Biogeochemical Dynamics of Particulate Organic Matter in the Shelf of the Northern South China Sea During Summer

AbstractEnvironmental conditions, physiology and community composition of phytoplankton and the carbon and nitrogen isotope signature (δ13CPOC and δ15NPN) of particulate organic matter (POM) often covary across marine environments. However, little was known on the link of δ13CPOC and δ15NPN and the community and biochemical composition of phytoplankton. In this study, particulate organic carbon (POC) and nitrogen (PN), δ13CPOC, δ15NPN, phytoplankton community composition and biomass were determined during summer, along with environmental variables, in the shelf of the northern South China Sea influenced by the Pearl River plume, upwelling and anticyclonic eddy. Our results show that variability in δ13CPOC and δ15NPN along an environmental gradient is coupled with shifts in phytoplankton community composition and carbon to chlorophyll a (C:Chl a) ratio of phytoplankton. Low δ13CPOC values (−28.4 to −27.0‰) at nearshore stations (salinity <21) were primarily due to terrestrial POM input. High δ13CPOC (>−21.0‰) and δ15NPN (>5.6‰) values are most likely attributed to high abundance of diatoms induced by riverine nutrients in the plume‐impacted waters with intermediate salinity (21< salinity <33). Low δ13CPOC (<−22.0‰) and δ15NPN (−1.1–3.7‰) values are associated with high abundance of slow‐growing cyanobacteria in the oligotrophic area (salinity >33), where the lowest δ15NPN is most likely attributed to high abundance of N2‐fixing Trichodesmium spp., due to the influence of the anticyclonic eddy. Therefore, hydrodynamics modulates the biochemical composition and community composition of phytoplankton, leading to changes in δ13CPOC and δ15NPN. Our findings advance our understanding of the coupling of physical and biogeochemical processes in marginal seas.

Regional-scale disturbances drive long-term decline of inshore coral reef fish assemblages in the Great Barrier Reef Marine Park.

Anthropogenic pressure is increasing the variety and frequency of environmental disturbance events, limiting recovery and leading to long-term declines in wild plant and animal populations. Coral reefs and associated fish assemblages are inherently dynamic due to their susceptibility to a host of disturbances, but regional-scale nuances in the drivers of long-term change frequently remain poorly resolved. Here, we examine the effects of multiple potential drivers of change in coral reef fish assemblages across 4 inshore regions of the Great Barrier Reef Marine Park (GBRMP), Australia, over 12-14 years (2007-2021). Each region had a unique disturbance history, in conjunction with long-term changes in physical and habitat variables. Phases of recovery were apparent in the years between disturbance events at all locations, but these were not long enough to prevent substantial declines in reef fish density (by 33%-72%) and species richness (by 41%-75%) throughout the study period. The main drivers of change in fish assemblages varied among regions; however, the most rapid changes followed cyclone and flood events. Limited recovery periods resulted in temporal shifts in fish species composition from typically coral-associated to algae-associated. Most trophic groups declined in density except farmers, grazers, omnivores and parrotfish. No-take marine reserves (NTMRs) had small and inconsistent effects on total fish assemblages, but delivered benefits for fishery-targeted piscivores. Our findings suggest that coral reef responses to local stressors and cumulative escalating climate change impacts are highly variable at regional scales, and that small NTMRs are unlikely to mitigate the impacts of increasingly frequent climatic disturbances. Nearshore coral reefs worldwide are high-value habitats that are either already degraded or vulnerable to degradation and the loss of important fish groups. Global efforts to reduce greenhouse gas emissions must be coupled with effective local management that can support the functioning and adaptive capacity of coral reefs.

Assessing the Effects of Habitat Loss and Deterioration on a Red Squirrel Translocation Site: Insights for Future Conservation Management.

Translocations, a conservation tool used to conserve and restore dwindling species, are often associated with high failure rates. Inadequate long-term monitoring of both populations and their introduction sites beyond the initial years post-translocation creates a gap in our understanding of the factors that determine translocation success or failure, resulting in less informed projects in the future. This lack of long-term monitoring is partly caused by the absence of a well-defined framework by which the success of the translocation can be measured, leading to premature and sometimes inaccurate assessments of their outcome. We investigated the long-term outcome of a red squirrel translocation in the west of Ireland, specifically assessing the habitat changes in the translocation site since the introduction in 2005, and their impact on the capacity of the forest to sustain a population of a given size. Using digitised historical map data, we showed that the translocation site experienced a 53% reduction in suitable habitat. Additionally, there was a 41%-81% reduction in the total number of red squirrels the forest could support, according to feeding survey data. Clear-felling, a forest fire and a shift in tree species composition collectively contributed to this decline in site suitability. This investigation underscores the complexity of translocation projects and emphasises the pivotal role of habitat quality in their outcomes. We advocate for detailed habitat assessments during the planning phase, avoidance of unstable habitats as translocation sites, and the implementation of long-term monitoring practices.

Enhanced phosphorus availability and cadmium remediation using phosphate-solubilizing bacteria-loaded biochar in contaminated soils

Phosphate-solubilizing bacteria (PSB) have garnered extensive attention for their ability to improve soil phosphorus (P) availability and their potential applications in bioremediation. However, the efficacy of PSB is contingent upon their colonization in soils, which can be hindered by the toxicity of heavy metals such as cadmium (Cd). Utilizing biochar as a protective carrier for PSB presents a promising strategy to address this challenge. This study investigated the effects of PSB-loaded biochar on soil P pools and wheat (Triticum aestivum L.) growth under Cd-contaminated conditions. Results indicated that biochar loading facilitated the colonization and functioning of the inoculated PSB strain (Bacillus subtilis), as evidenced by increased soil cultivatable PSB abundance and phosphatase activity as well as increased relative abundance of Bacillus in bacterial community. Consequently, improved soil P availability and reduced soil exchangeable Cd content were observed, leading to a 30.3% increase in wheat shoot biomass, a 50.4% increase in P accumulation, and a 24.1% reduction in Cd accumulation in wheat shoots under the PSB-loaded biochar treatment. Significant shifts in bacterial community composition were revealed by 16S rRNA amplicon sequencing and enhanced microbe-mediated metabolic activities were observed, as demonstrated by soil enzyme assays and metabolome analysis. Overall, these findings underscore the potential of PSB-loaded biochar to enhance P availability, mitigate Cd toxicity, and shape the soil microbial community, offering a promising strategy for sustainable nutrient management and bioremediation in Cd-contaminated agricultural soils.

Insights into the carbon and nitrogen metabolism pathways in mixed-autotrophy/heterotrophy anammox consortia in response to temperature reduction

While the multi-coupled anammox system boasts a substantial research foundation, the specific characteristics of its synergistic metabolic response to decreased temperatures, particularly within the range of 13-15°C, remained elusive. In this study, we delve into the intricate carbon and nitrogen metabolism pathways of mixed-autotrophy/heterotrophy anammox consortia under conditions of temperature reduction. Our macrogenomic analyses reveal a compelling phenomenon: the stimulation of functional genes responsible for complete denitrification, suggesting an enhancement of this process during temperature reduction. This adaptation likely contributes to maintaining system performance amidst environmental challenges. Further metabolic functional recombination analyses highlight a dramatic shift in microbial community composition, with denitrifying MAGs (metagenome-assembled genomes) experiencing a substantial increase in abundance (up to 200 times) compared to autotrophic MAGs. This proliferation underscores the strong stimulatory effect of temperature reduction on denitrifying species. Notably, autotrophic MAGs play a pivotal role in supporting the glycolytic processes of denitrifying MAGs, underscoring the intricate interdependencies within the consortia. Moreover, metabolic variations in amino acid composition among core MAGs emerge as a crucial adaptation mechanism. These differences facilitate the preservation of enzyme activity and enhance the consortia's resilience to low temperatures. Together, these findings offer a comprehensive understanding of the microbial synergistic metabolism within mixed-autotrophy/heterotrophy anammox consortia under temperature reduction, shedding light on their metabolic flexibility and resilience in dynamic environments.

Interactive effects of aridity and local environmental factors on the functional trait composition and diversity of macroinvertebrate assemblages in dryland rivers

Drought and local habitat alteration are major environmental stressors shaping the aquatic biota in dryland rivers. However, the combined effects of these factors on aquatic biodiversity remain poorly understood. We collected macroinvertebrate data from Central Asian dryland rivers in Xinjiang, China, from 2012 to 2022, to investigate the individual and interactive effects of drought (as indicated by increasing values of Aridity, AI) and local habitat conditions (fine sediments, velocity and pH) on aquatic macroinvertebrate functional trait composition and diversity. We found that interactions of the selected environmental stressors exhibited more frequent additive than synergistic or antagonistic effects, leading to shifts in macroinvertebrate functional trait composition and diversity accordingly. Interaction of AI and fine sediments showed more pronounced synergistic effects (positive or negative) compared to others and had positive influences on traits like small body size, ovoviviparity, etc. Functional diversity metrics responded differently to stressor interactions, with FRic and FDis being negatively affected, whereas FEve was positively correlated to stressor interaction, suggesting the complementary roles of functional diversity metrics to diagnose impacts of stressor interactions. Overall, our study provides new insights into macroinvertebrate assemblage-stressor relationships in dryland rivers and can help better assess, predict and manage aquatic biodiversity in these rivers under ongoing environmental change.

Phase composition of sputter deposited tungsten thin films

Sputter deposited tungsten thin films are studied by X-ray diffraction. Two phases can be identified: α-W and β-W based on the observed (110), and (200) and (210) Bragg reflections, respectively. With increasing film thickness (50 to 200 nm), the phase composition shifts from β-W towards α-W. No influence of the base pressure (3 × 10−3 – 3 × 10−5 Pa) on the phase composition is observed. Also the influence of the argon pressure (0.3 to 0.7 Pa) is rather weak. The strongest shift towards α-W composed thin films is obtained by increasing the discharge power (50 to 250 W). This trend is further studied by energy flux measurements using a calorimetric probe. These measurements rule out a strong change of the substrate temperature, and an impact of the energy flux scaled by the deposition rate (total energy per deposited atom). Test particle Monte Carlo simulations reveal the importance of the momentum of the reflected argon neutrals on the phase composition. The maximum energy of these species is mainly defined by the discharge voltage, and is higher than the directional dependent displacement energy of W. Despite the significant correlation between phase composition and the number of displacement per deposited atom, there is a strong scatter of the phase composition. As the deposition conditions were varied in random way, changes of the target erosion profile, and the changing discharge voltage over each series are probably partially responsible for the observed scatter. This scatter is also enhanced by the long term changes in the phase composition towards the more thermodynamic stable α-W phase.