Species Richness Research Articles

Ash dieback: A single-species catastrophe or a cascade of ecological effects in the ground flora?

Climate change and human activities have accelerated the spread of non-native species, including forest pests and pathogens, significantly contributing to global biodiversity loss. Pathogens pose a significant threat to forest ecosystems due to a lack of coevolution with native hosts, resulting in ineffective defence mechanisms and severe consequences for the affected tree species. Ash dieback, caused by the fungus Hymenoscyphus fraxineus, is a relatively new invasive forest pathogen threatening ash (Fraxinus excelsior) with mortality rates in northern Europe reaching up to 80 %. The loss of ash due to dieback has severe ecological implications, potentially leading to an extinction cascade as ash provides crucial habitats and resources for many organisms. Despite this, the consequences of ash dieback on associated communities are largely unknown. To address this, we analysed changes in species richness, vegetation structure, and composition in 82 permanent vegetation plots across 23 Norwegian woodlands. We compared data collected before and 10–14 years after the emergence of ash dieback. In these woodlands, ash significantly declined in cover, leading to changes in tree species composition and facilitating the establishment of other woody tree species like hazel (Corylus avellana) and the invasive species sycamore (Acer pseudoplatanus). Despite these changes in the tree species composition, no significant alterations were observed in the understory plant community, indicating a degree of ecosystem resilience or a lagging community response. At this point, and with our focus on the vascular plants, we do not find support for cascading effects due to ash dieback. However, our findings demonstrate that one invasive species is facilitating the expansion of another, raising concerns about potential ecological imbalance and cascading effects in the future.

Diversity, Composition and Distribution Patterns of Spiders (Arachnida: Araneae) in Sand Forest, South Africa

ABSTRACTSpiders are the dominant representative of the top predator guild in many terrestrial ecosystems, but their diversity and distribution in forests in South Africa are still understudied. This study aimed to determine ground‐dwelling spider diversity, composition and distribution patterns in both sand forest and savanna (and their ecotone) using pitfall traps and to provide a spider species checklist for these three habitats in Phinda Private Game Reserve. A total of 410 individuals from 64 species and 21 families were recorded from the three habitat types. The Lycosidae family and Pardosa crassipalpis were the most dominant family and species. Spider abundances were similar between sand forest and the ecotone, but lower in savanna. However, species richness was similar across habitats. Spider species assemblages were similar between sand forest and the ecotone, but differed from the species assemblages in savanna. Spiders play an important role in food webs both below‐ and aboveground. Therefore, determining their diversity and distribution contributes to the overall understanding of the ecosystem in addition to promoting conservation efforts of key habitats such as the critically endangered sand forest.

Effects of graphene oxide composite additive on the species abundance and diversity of microorganisms in saline-alkali soil

Saline-alkali soil is common in north China, especially in the Datong district in north Shanxi province. Improving the soil will benefit the environment and society. Graphene oxide (GO) has been shown to benefit agricultural and forest soils. Herein we explore three different experimental conditions of CK (CK means irrigated with tap water), CJ (CJ means 0.2 g of bacteria addition and irrigated with tap water) and CJ25 (CJ25 means 0.2 g of composited bacteria plus 25.0 mg/L of graphene oxide added and irrigated with tap water) for saline-alkali soil by the addition of optimized amounts of graphene oxide and external bacteria. Our results show that the addition of 25.0 mg/L graphene oxide and microbial agents increases the number of bacteria and fungi in the soil and improves the species abundance of bacteria and fungi in the saline-alkali soil, while having little effect on species richness. The graphene oxide and bacterial treatment increased the abundance of Proteobacteria, Actinobacteriota, Chloroflexi, Pseudomonas, Ascomycota, Mortierella and Fusarium. These bacteria have been shown to produce proteolytic enzymes and cellulases that decompose lignin and cellulose in litter, and thus play important roles in carbon and nutrient cycling. The addition of graphene oxide and microorganisms provide a viable way to improve saline-alkali soils.

Elevational patterns of bird alpha and beta diversity in Haba Snow Mountain, Southwestern China: Implication for conservation

Understanding environmental patterns of species diversity is essential for nature reserve planning and biodiversity conservation. In this study, we explored the birds’ alpha and beta diversity along the elevational gradients in Haba Snow Mountain Nature Reserve (hereafter, HBSM), a global biodiversity hotspot, and studied which environmental factor is the main driver in explaining alpha and beta diversity patterns. Our results indicated that taxonomic, functional, and phylogenetic alpha diversity consistently exhibited hump-shaped patterns with similar peaks. After controlling for species richness, both functional and phylogenetic alpha diversity increased with elevation, and the peaks at 3400–3700 m. Mean pairwise functional distance remained nearly constant along the elevation band, whereas mean pairwise phylogenetic distance shown hump-shaped pattern, and the predicted MPD peaked at the fifth band (3100–3400 m a.s.l). The functional and phylogenetic structure of bird communities in HBSM were more clustered along the elevation gradients, suggesting environmental filtering likely drove the assembly processes. Additionally, primary productivity (NDVI and/or habitat heterogeneity) and/or precipitation were robust predictors of variation in most diversity metrics. For multiple-site beta diversity, we observed that high turnover component in taxonomic, functional, and phylogenetic dimensions, indicating distinct bird assemblages across various elevational bands. In pairwise beta diversity, the spatial turnover of taxonomic and phylogenetic aspects was higher than nestedness, revealing species replacement occurs relatively frequently between evolutionarily related species with similar niche and functional traits. Overall, our findings highlight the importance of considering both different dimensions and multifaceted diversity when assessing elevational patterns of bird diversity. This study also provides valuable insights into the structuring mechanisms of bird communities and informs conservation planning along elevational gradients in HBSM, and offers a comprehensive case on species richness along elevational gradients.

Spatial distribution and composition of benthic macro-invertebrate in upper Awash River, below and upper Ginchi town, West Shoa Zone, Ethiopia

The composition and distribution of macro-invertebrates of benthic species can be influenced by water quality. The primary objective of this study was to understand the spatial distribution and composition of macro-invertebrates of benthic nature in the upper Awash River below and above Ginchi Town. The study was carried out for a period of three months from February 2020 to April 2020, and macro-invertebrates samples were collected from three stations using Surber sampler with 500 μ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\upmu$$\\end{document}m/mesh size and 25 cm × 25 cm (0.0625 m2) of sampling area coverage. The present study showed that, in the study area, there was a low density of macro-invertebrates and species richness in general with a comparative difference between the pool riffle habitats in density and family richness. And the total abundance of benthic macro-invertebrates showed a positive correlation with NO3-N, dissolved oxygen, and total phosphorus, while a negative correlation with all the other physicochemical parameters measured during the study period. Spatial and monthly variations in the diversity and richness of benthic macro-invertebrates were attributed to the effects of human action and changes in environmental factors. So, the water shade management system should be applied to control pollution factors that can affect the macro-benthic fauna community.

Metagenomic profiling of cecal microbiota and antibiotic resistome in rodents

The rodent gut microbiota is a known reservoir of antimicrobial resistance, yet the distribution of antibiotic resistance genes (ARGs) within rodent cecal microbial communities and the specific bacterial species harboring these ARGs remain largely underexplored. This study employed high-throughput sequencing of 122 samples from five distinct rodent species to comprehensively profile the diversity and distribution of ARGs and to identify the bacterial hosts of these genes. A gene catalog of the rodent cecal microbiome was constructed, comprising 22,757,369 non-redundant genes. Analysis of the microbial composition and diversity revealed that Bacillota and Bacteroidota were the dominant bacterial phyla across different rodent species, with significant variations in species composition among the rodents. In total, 3703 putative antimicrobial resistance protein-coding genes were identified, corresponding to 392 unique ARG types classified into 32 resistance classes. The most enriched ARGs in the rodent cecal microbiome were associated with multidrug resistance, followed by glycopeptide and elfamycin antibiotics. Procrustes analysis demonstrated a correlation between the structure of the microbial community and the resistome. Metagenomic assembly-based host tracking indicated that most ARG-carrying contigs originated from the bacterial family Oscillospiraceae. Additionally, 130 ARGs showed significant correlations with mobile genetic elements. These findings provide new insights into the cecal microbiota and the prevalence of ARGs across five rodent species. Future research on a wider range of wild rodent species carrying ARGs will further elucidate the mechanisms underlying the transmission of antimicrobial resistance.

Mechanism Insight into Direct Amidation Catalyzed by Zr Salts: Evidence of Zr Oxo Clusters as Active Species.

The capricious reactivity and speciation of earth-abundant metals (EAM) hinder the mechanistic understanding essential to boost their efficiency and versatility in catalysis. Moreover, metal's solution chemistry and reactivity are conventionally controlled using organic ligands, while their fundamental chemistry in operando conditions is often overlooked. However, in this study, we showcase how a better understanding of in operando conditions may result in improved catalytic reactions. By assessing the composition and structure of active species for Zr-catalyzed direct amide bond formations under operating conditions, we discovered zirconium oxo clusters form quickly and are likely active species in the reactions. Formation of these clusters dismisses the use of additional organic ligands, inert atmosphere, anhydrous solvents, or even water scavenging to provide amides in good to excellent yields. More specifically, dodeca- and hexazirconium oxo clusters (Zr12 and Zr6, respectively) rapidly form from commercial, readily available Zr salts under reaction conditions known to afford amides directly from nonactivated carboxylic acid and amine substrates. Extended X-ray absorption fine structure (EXAFS) experiments confirm the presence of oxo clusters in solution throughout the reaction, while their key role in the mechanism is supported by an in-depth computational study employing density functional theory (DFT) and molecular dynamics (MD) methods. These results underline the value of (earth-abundant) metals' intrinsic solution chemistry to transformative mechanistic understanding and to enhance the sustainability of organic transformations.

Plant diversity increases diversity and network complexity rather than alters community assembly processes of leaf-associated fungi in a subtropical forest.

Plant diversity significantly impacts ecosystem processes and functions, yet its influence on the community assembly of leaf fungi remains poorly understood. In this study, we investigated leaf epiphytic and endophytic fungal communities in a Chinese subtropical tree species richness experiment, ranging from 1 to 16 species, using amplicon sequencing to target the internal transcribed spacer 1 region of the rDNA. We found that the community assembly of epiphytic and endophytic fungi was predominantly governed by stochastic processes, with a higher contribution of dispersal limitation on epiphytic than on endophytic fungal communities but a higher contribution of selection on endophytic than on epiphytic fungal communities. The plant-epiphytic fungus interaction network was more complex (e.g., more highly connected and strongly nested but less specialized and modularized) than the plant-endophytic fungus interaction network. Additionally, tree species richness was positively correlated with the network complexity and diversity of epiphytic (α-, β- and γ-diversity) and endophytic (β- and γ-diversity) fungi, but was not associated with the contribution of the stochastic and deterministic processes on the community assembly of epiphytic and endophytic fungi. This study highlights that tree species diversity enhances the diversity and network complexity, rather than alters the ecological processes in community assembly of leaf-associated fungi.

Tracing the dynamic ecology of microbial biofilms on steel with prolonged submersion in surface water

Amplicon sequencing is applied to monitor microbial species residing in the biofilm that formed on steel surface submerged in surface water along the Ghent Terneuzen canal, stretching 31 kms from Belgium to the Netherlands. Temporal and spatial differences in the biofilm microbiota were revealed by 16S rRNA composition analysis. The loss-of-mass from S235 steel coupons showed uniform corrosion rates ranging from 242 to 906 g/m2 after 3 months. Notably, enhanced pitting corrosion was seen at one specific location near ‘Heide’ affecting the surface with depths up to 1210 µm after 6 months. We presume the excessive steel deterioration in micro-cavities is associated with microbial activity of iron-oxidising bacteria (IOB) and sulphur-reducing bacteria (SRB), such as Shewanella spp . and Gallionella spp., respectively, as redox-active species. Indications for microbially induced corrosion (MIC) are highlighted at sites with apt microbial composition, irrespective of physico-chemical water parameters. Coupons affected by high corrosion and assumed MIC did not stand out in terms of species richness and alpha diversity did not increase, suggesting partial take-over of the microbial community by IOB or SRB.

The impact of combined application of biochar and fertilizer on the biochemical properties of soil in soybean fields.

Heilongjiang Province is a major soybean production area in China. To improve soil structure and increase soybean yield, this study examined the effects of combined biochar and chemical fertilizer application on the biochemical properties of soil in a maize-soybean rotation system. The research were conducted from 2021 to 2022 at Heshan Farm Science Park in Heilongjiang Province, this field plot experiment utilized two soybean varieties, Heihe 43 (a high-protein variety) and Keshan 1 (a high-oil variety). In 2021, two plots with similar fertility levels were selected for planting soybeans and maize. In 2022, a maize-soybean rotation was implemented with five treatments: conventional fertilization (CK), increased biochar+reduced fertilizer 1 (F1+B), reduced fertilizer 1 (F1), increased biochar+reduced fertilizer 2 (F2+B), and reduced fertilizer 2 (F2). The study systematically analyzed the effects of combined biochar and chemical fertilizer application on soil chemical properties and microbial characteristics. Over 2 years, results showed that combined application effectively improved soil chemical traits. Compared to conventional fertilization (CK) and reduced fertilization (F1, F2), t he combined application of biochar and chemical fertilizer (F1+B, F2+B) increased soil pH, EC and the absolute value of zeta potential of soil surface, the CEC of soil significantly increased by 15.6-44.3%, the soil surface charge density and the soil surface charge quantity significantly increased by 16.4-73.5%. The combined application of biochar and chemical fertilizer also effectively enhanced the abundance and diversity of soil microbes. Dominant bacterial groups in soybean field soils under different treatments included Actinobacteria, Acidobacteria, Chloroflexi, and Proteobacteria; while dominant fungal groups were Ascomycota, Basidiomycota, and Mortierellomycota. Alpha and Beta diversity analyses revealed that the F1+B treatment significantly enhanced the species richness and diversity of bacteria and fungi in the soil, increasing the proportion and evenness of dominant and beneficial genera.

Tetramerium (Acanthaceae) in the Depresión del Balsas Biogeographic Province of Mexico, two new species and a new combination

A taxonomic account of Tetramerium in the Depresión del Balsas Biogeographic Province of western and central Mexico reveals 14 species there, with 2 of them, T. cruzii and T. michoacanum, described herein. A new combination, T. barlerioides, is proposed for the species previously known as T. ochoterenae. This region of Mexico appears to be the center of both species richness and morphological diversity for this widely distributed American genus. A key to the 14 species is followed by geographic distribution ranges, ecological data within the region, and miscellaneous notes for each one that updates information from the last monograph of the genus. A verified voucher specimen is provided to document species occurrences in each state (or portion of a state) in the Depresión del Balsas. Occurrences of 2 species, T. glandulosum and T. tenuissimum, are newly reported from the Estado de México. A map of the region and floral photographs of 12 of the species are provided.

Taxonomic re-evaluation of the Brachionus calyciflorus species complex (Rotifera) in Japanese freshwaters

AbstractRecently, the Brachionus calyciflorus species complex was divided into four nominal species: B. calyciflorus sensu stricto (s.s.) Pallas, 1766; Brachionus dorcas Gosse, 1851, Brachionus elevatus Michaloudi et al., 2018, and Brachionus fernandoi Michaloudi et al., 2018 based on the results of both morphological and molecular investigations. We applied this systematic approach to B. “calyciflorus” collected from lakes and ponds in various parts of Japan to examine spatial and temporal distributions of these species. We found that all four species indeed distributed in Japan. Among the species, B. fernandoi exhibited a somewhat different occurrence pattern and morphology. Generally, B. fernandoi appeared to occur in the winter–spring, while the other three species seemed to occur in the early summer–late autumn. A seasonal succession from B. fernandoi-dominant community to other species-dominant communities was observed in the same lakes/ponds. A statistical analysis showed that B. fernandoi-dominant species composition was also related to low temperatures. It was also found that the body of B. fernandoi was more elongated compared to those of other species. These results suggest that B. fernandoi is a distinct species in terms of morphology and phenology. Among the other three species, we observed a variation in the length of posterolateral spines. However, it was not clear if this variation is a trait that distinguish these species morphologically. In addition, some of these species co-occurred in the same lakes and ponds. The mechanism by which they coexist is a topic for future study.

Wildlife-Vehicle Collisions and Mitigation: Current Status and Factor Analysis in South Korea.

Severe habitat loss and fragmentation due to extensive road development have escalated wildlife-vehicle collisions (WVCs) as one of the major causes of wildlife mortality. This study, spanning 9 years from 2009 to 2017, presents comprehensive WVC data in South Korea, including species composition, seasonal and regional patterns, and road factors influencing WVCs, aiming to analyze their impact and propose effective mitigation strategies. We collected WVC data with road variables for 9 years from 4561 km of nationwide monitoring road sections and analyzed the data to understand the relationship between WVCs and road characteristics, as well as species-specific patterns. A nationwide survey identified 13,606 WVCs involving 143 terrestrial vertebrate species, and patterns and models of the top seven mammal species (raccoon dog (Nyctereutes procyonoides), Siberian chipmunk (Eutamias sibiricus), Siberian weasel (Mustela sibirica), water deer (Hydropotes inermis), red squirrel (Sciurus vulgaris), Korean hare (Lepus coreanus), and leopard cat (Prionailurus bengalensis)) were presented. Patterns revealed declines in WVCs overall, except for water deer. Although spatial differences in WVCs seemed linked more to wildlife habitats, certain road features correlated both positively or negatively with WVC frequency, highlighting complexities in the effectiveness of preventative measures. For effective mitigation and prevention of WVCs, comprehensive strategies considering species traits, seasonality, and road types should be implemented.

Diversity and abundance of large old trees in Hainan Island: Spatial analysis and environmental correlations

AbstractLarge old trees (LOTs) are invaluable natural treasures and cultural legacies, holding ecological, historical, social, and economic significance. However, climate change and human impacts threaten their existence. Understanding their species composition, age structure, biomass, and distribution patterns in relation to environmental factors is essential for effective conservation. In Hainan Island, South China, we analyzed 1081 LOTs from 74 species across 35 families, using a combination of field surveys and government data. The dominant families were Moraceae, Sapindaceae, and Fagaceae, with key species including Ficus altissima, Litchi chinensis, and Tamarindus indica. The age distribution followed a reverse J‐shape, indicating a prevalence of trees aged 300–399 years. In contrast, diameter at breast height (DBH) and height distributions were unimodal, favoring medium to large‐sized trees. Spatial analysis revealed uneven distribution patterns: the western zone exhibited the highest species diversity, the central zone moderate diversity, and the eastern zone low diversity, reflecting uneven urban and agricultural impacts. Most LOTs were concentrated at elevations of 0–50 m. Factors such as GDP, urbanization, and forest cover positively correlated with LOT abundance and diversity, with forest cover and average annual temperature particularly favoring these trees. The findings emphasize the intricate relationship between environmental factors and LOT distribution. They advocate for tailored conservation strategies that address the complex interplay of ecological, socioeconomic, and cultural influences on their preservation.Abstract in Chinese is available with online material.

Review of ecological valuation and equivalency analysis methods for assessing temperate nearshore submerged aquatic vegetation.

Nearshore seagrass, kelp, and other macroalgae beds (submerged aquatic vegetation [SAV]) are productive and important ecosystems. Mitigating anthropogenic impacts on these habitats requires tools to quantify their ecological value and the debits and credits of impact and mitigation. To summarize and clarify the state of SAV habitat quantification and available tools, we searched peer-reviewed literature and other agency documents for methods that either assigned ecological value to or calculated equivalencies between impact and mitigation in SAV. Out of 47 tools, there were 11 equivalency methods, 7 of which included a valuation component. The remaining valuation methods were most commonly designed for seagrasses and rocky intertidal macroalgae rather than canopy-forming kelps. Tools were often designed to address specific resource policies and associated habitat evaluation. Frequent categories of tools and methods included those associated with habitat equivalency analyses and those that scored habitats relative to reference or ideal conditions, including models designed for habitat suitability indices and the European Union's Water and Marine Framework Directives. Over 29 tool input metrics spanned 3 spatial scales of SAV: individual shoots or stipes, bed or site, and landscape or region. The most common metric used for both seagrasses and macroalgae was cover. Seagrass tools also often employed density measures, and some categories used measures of tissue content (e.g., carbon, nitrogen). Macroalgal tools for rocky intertidal habitats frequently included species richness or incorporated indicator species to assess habitat. We provide a flowchart for decision-makers to identify representative tools that may apply to their specific management needs.

Forest restoration benefits common and rare wood-decomposing fungi with a delay

Decline in the amount of dead wood deteriorates habitats for saproxylic organisms globally. This could be compensated by restoration, but it is poorly understood how created dead wood corresponds to the habitat requirements of saproxylic species. Using a large-scale field experiment of 30 restoration sites across Finland, we studied the long-term (5–15 years) effects of dead wood creation on wood-decomposing fungi (polypores) in Norway spruce and Scots pine dominated forests. All studied conservation areas had been used for timber production prior to conservation. The average amount and diversity of woody debris was higher on the restoration treatments than on the non-restored controls. Altogether, 56 polypore species were recorded. Restoration treatments had 1.4 and 8 times more species and observations than controls. Eight red-listed polypore species were observed, six on the restored plots (four only from the created dead wood) and two on the controls. Species composition of polypore assemblages differed between the restoration and control treatments, as well as between the spruce- and pine-dominated forests. Following restoration, temporal changes in the polypore assemblages were clear but only partly related to dead wood creation. Unlike previous short-term studies, our results show that dead wood creation by felling and ring-barking trees benefits not only common but also indicator and red-listed polypore species; indeed, 15 years after restoration all red-listed species occurred on created dead wood. As some red-listed species occurred solely on naturally fallen trees five to ten years after restoration, created dead wood alone cannot substitute for natural dead wood.

Pollinator diversity of the food-deceptive orchids in southern Italy.

The orchid family is renowned for its enormous diversity in pollination biology. Many orchid species use deception to attract pollinators, and the main strategy in terrestrial orchids is food deception. Food-deceptive orchids usually show a low number of pollinator visitations, making field observations of pollinators difficult. In this study visual census, pollinator capture and molecular analysis of pollinaria found on caught insects allowed us to obtain information on species composition of orchid pollinators. A total of 321 insects were caught; most specimens were hymenopterans (Apis mellifera, Bombus ruderatus and Eucera rufa) and coleopterans (Tropinota hirta and T. squalida). The identity of species to which pollinaria found on the insect's body belonged was confirmed by molecular analysis. Moreover, some individuals of Billaea lata (Tachinidae, Diptera) were captured and photographed with the pollinaria on their head. Two new and important results emerged clearly in this work: a dipteran, Billaea lata, pollinator of Anacamptis pyramidalis, and two beetles in the genus Tropinota are pollinators of Orchis italica. Our results confirm that generalized food-deceptive orchids of the genera Orchis and Anacamptis show weak pollinator specificity.

Seagrass Biodiversity Under the Latest‐Generation Scenarios of Projected Climate Change

ABSTRACTAimThe potentially cascading consequences of climate changes on redistribution of habitat‐forming species, like seagrasses, remain a major research gap. Empirical demonstrations of local population changes are increasingly reported without a globally integrated predictive framework as a leading testable hypothesis. Therefore, here, we aimed to estimate changes in species richness, community composition, and areas of climatic refugia under future climate scenarios.LocationGlobal scale.Time PeriodPresent‐day conditions (from 2010 to 2020) and for three Shared Socioeconomic Pathway (SSP) scenarios of future climate change (from 2090 to 2100).Major Taxa StudiesSeagrasses (plantae).MethodsWe coupled seagrass occurrences with environmental predictors (temperature, salinity, nitrate, wave energy, and ice) in stacked species distribution modelling.ResultsModels estimated a present global extent of 917,169 km2 with high species richness in Temperate Australasia, Indo‐Pacific, and Temperate North Pacific. Future projections predicted widespread spatial redistribution, with Arctic expansions, losses in lower latitudes, and deeper vertical ranges, while globally maintaining the area extent occupied worldwide by seagrass species (only 5% of change). Species richness increased poleward under more drastic scenarios (SSP3‐7.0 and SSP5‐8.5), with losses in tropical zones (30oN to 30oS). Local climatic refugia are retained in all scenarios but decrease under higher emissions. Additionally, even where seagrass species remain, widespread community composition changes were predicted.Main ConclusionsOur findings serve as baselines to inform, anticipate, and mitigate cascading consequences of shifts in seagrass ecosystems that provide essential services for humanity.

Secular change in seaweed species composition and coverage of Sargassaceae on the artificial reef in Wakasa Bay, Japan.

The threat of declining seaweed beds has been a concern around the world. Seagrass and seaweed (brown algae) beds are essential habitats supporting fisheries. However, approximately 22% of these habitats have been lost in Japan due to increased coastal landfill sites and ports. This study aims to rehabilitate the depletion of these habitats by constructing an artificial reef in Wakasa Bay, Japan, and monitoring Sargassaceae succession in the second and fourth years after the construction was completed. In this study, we set up four sites on the artificial reef. Then we identified the seaweed species composition and coverage of the Sargassaceae using underwater visual observation by scuba divers. The seaweed coverage was already over approximately 80% in the second year after construction. The Sargassum horneri and S. confusum dominated during the first and second sampling in the second year after construction, and Myagropsis myagroides and S. patens during the third and fourth sampling in the fourth year after construction. Thus, the recovery of species composition takes longer than that of coverage. Therefore, observing species composition recovery is essential when constructing the artificial reef.

Stability of Gastric Fluid and Fecal Microbial Populations in Healthy Horses under Pasture and Stable Conditions.

Equine gastrointestinal microbial communities vary across the gastrointestinal tract and in response to diet or disease. Understanding the composition and stability of gastric fluid microbiota in healthy horses is a prerequisite to understanding changes associated with the development of disease. The objective of this study was to describe microbial communities in the gastric fluid and feces of healthy horses longitudinally. Horses were maintained on pasture (6 weeks), stabled (5 weeks), then returned to pasture. A consistent forage diet was provided throughout. Native gastric fluid and feces were collected weekly for full-length 16S ribosomal DNA sequencing and microbial profiling analysis. Fewer taxa were identified in the gastric fluid (770) than in the feces (5284). Species richness and diversity were significantly different between sample types (p < 0.001), but not between housing locations (p = 0.3). There was a significant effect of housing and horse on the Bray-Curtis compositional diversity of gastric (p = 0.005; p = 0.009) and fecal (p = 0.001; p = 0.001) microbiota. When horses moved from pasture to stable, the relative proportions of gastric fluid Lactobacillaceae increased and Streptococcaceae decreased, while fecal Firmicutes increased and Bacteriodota decreased. Within each housing condition, there was no significant week-to-week variation in gastric (p = 0.9) or fecal (p = 0.09) microbiota. Overall, these findings support the maintenance of stable gastric and fecal microbial populations under each management condition, providing a basis for further investigation of gastric fluid microbiota in diseases of the foregut.