Search Results (119)

In this cross-disciplinary investigation, we uncover a suite of previously unexamined factors and their intricate interplay that hold causal relationships with the distribution of Trachurus japonicus in the northern reaches of the South China Sea, thereby extending the existing research paradigms. Leveraging advanced machine learning algorithms and causal inference, our robust experimental design uncovered nine key global and regional factors affecting the distribution of T. japonicus density. A robust experimental design identified nine key factors significantly influencing this density: mean sea-level pressure (msl-0, msl-4), surface pressure (sp-0, sp-4), Summit ozone concentration (Ozone_sum), F10.7 solar flux index (F10.7_index), nitrate concentration at 20 m depth (N3M20), sonar-detected effective vertical range beneath the surface (Height), and survey month (Month). Crucially, stable causal relationships were identified among Ozone_sum, F10.7_index, Height, and N3M20. Variations in Ozone_sum likely impact surface UV radiation levels, influencing plankton dynamics (a primary food source) and potentially larval/juvenile fish survival. The F10.7_index, reflecting solar activity, may affect geomagnetic fields, potentially influencing the migration and orientation behavior of T. japonicus. N3M20 directly modulates primary productivity by limiting phytoplankton growth, thereby shaping the availability and distribution of prey organisms throughout the food web. Height defines the vertical habitat range acoustically detectable, intrinsically linking directly to the vertical distribution and availability of the fish stock itself. Surface pressures (msl-0/sp-0) and their lagged effects (msl-4/sp-4) significantly influence sea surface temperature profiles, ocean currents, and stratification, all critical determinants of suitable habitats and prey aggregation. The strong influence of Month predominantly reflects seasonal changes in water temperature, reproductive cycles, and associated shifts in nutrient supply and plankton blooms. Rigorous robustness checks (Data Subset and Random Common Cause Refutation) confirmed the reliability and consistency of these causal findings. This elucidation of the distinct biological and physical pathways linking these diverse factors leading to T. japonicus density provides a significantly improved foundation for predicting distribution patterns globally and offers concrete scientific insights for sustainable fishery management strategies. Full article

This study aims to reveal the impact mechanisms of five typical topographic habitats in the Sanjiangyuan region (sunny slope, depression, shady slope, mountain pass, and transitional zone) on the characteristics and functions of rhizosphere soil fungal communities of Kengyilia thoroldiana, and to elucidate the association patterns between these communities and soil physicochemical factors. The species composition, diversity, molecular co-occurrence network, and FUNGuild function of microbial communities were investigated based on high-throughput sequencing technology. By combining the Mantel test and RDA analysis, the key habitat factors affecting the structure of the soil fungal community in the rhizosphere zone of Kengyilia thoroldiana were explored. The results showed that: ① The composition of the soil fungal community in the rhizosphere of Kengyilia thoroldiana in five topographical habitats showed significant differentiation characteristics: the number of OTUs in H2 (depression) and H5 (transitional zone) habitats was the highest (336 and 326, respectively). Habitats H2 showed a significant increase in the abundance of Ascomycota and Mortierellomycota and a significant decrease in the abundance of Basidiomycota compared to the other topographical habitats. ② The diversity and aggregation degree of the soil fungal community in the rhizosphere of Kengyilia thoroldiana in five topographical habitats showed differences. ③ Cluster analysis showed that the rhizosphere soil fungi in five topographical habitats of Kengyilia thoroldiana could be divided into two groups, with H2, H4 (mountain pass), and H5 habitats as one group (group 1) and H1 and H3 (shady slope) as one group (group 2). ④ The characteristics of the Kengyilia thoroldiana community and the physical and chemical properties of rhizosphere soil in five topographical habitats were significantly different, and the height, coverage, biomass, and soil nutrient content were the highest in H2 and H5 habitats, while lower in H1 and H3 habitats, with significant differences (p < 0.05). ⑤ Redundancy analysis showed that soil water content was the main driving factor to change the structure and function of the soil fungal community in the rhizosphere of Kengyilia thoroldiana in five topographic habitats in the Sanjiangyuan region. This study demonstrated that topographic habitats affected the species composition, functional pattern, and ecosystem service efficiency of the Kengyilia thoroldiana rhizosphere fungal community by mediating soil environmental heterogeneity, which provides microbial mechanistic insights for alpine meadow ecosystem protection. Full article

Conservation units (CUs) play a fundamental role in maintaining and conserving biodiversity, and are important in preserving streams, reducing impacts from human activities and increasing water availability beyond the boundaries of the reserves. However, knowledge about the phytoplankton biodiversity of ecosystems in CUs is scarce. This study evaluated how environmental integrity alters microphytoplankton communities in extractive CUs and their surroundings in the southwestern Brazilian Amazon. Our results demonstrated that the streams exhibited distinct physicochemical and hydrological characteristics, representing spatially heterogeneous environments. Differences in habitat integrity values altered species composition in streams within and outside conservation units. Local beta diversity (LCBD) was negatively influenced by habitat integrity, indicating that sites with greater habitat integrity did not always present a greater number of unique species. The species Trachelomonas hispida, Gyrosigma scalproides and Spirogyra sp. were the ones that contributed the most to beta diversity. However, the phytoplankton species that contributed most to beta diversity were not always associated with streams with greater integrity, indicating that even environments that are less intact play a relevant role in maintaining species richness and beta diversity of microphytoplankton. Factors such as habitat integrity, pH, temperature and dissolved oxygen were the main influencers of microphytoplankton in the streams. Thus, the streams of both CUs and their surroundings, despite their physical–chemical and hydrological differences, effectively contribute to the high richness and beta diversity of regional microphytoplankton. Full article

Soil structure has an important role in storing and transporting substances, providing natural habitats for soil microorganisms, and allowing chemical reactions in the soil. A complex investigation on factors affecting soil structure characteristics under herbaceous (H), deciduous (D), mixed (M), and coniferous (SP—Scots Pine and NS—Norway Spruce) vegetation was conducted at three experimental stations—Gabra, Govedartsi, and Igralishte, located correspondingly in the Lozenska, Rila, and Maleshevska Mountains in South-West Bulgaria. The data set obtained includes soil structure indicators and physical, physicochemical, chemical, mineralogical, and microbiological parameters of the A and AC horizons of 11 soil profiles. Under different vegetation conditions, soil structure indicators respond differently depending on climatic conditions and basic soil properties. Regarding the plant available water capacity (PAWC), air capacity (AC), and water-stable aggregates (WSAs), the surface soil layers have an optimal structure in Gabra (H, D), Govedartsi (H, SP, NS), and Igralishte (H). The values for the relative field capacity (RFC < 0.6) showed that the studied soils were water-limited. The WSAs correlated with SOC in Gabra, while in Govedartsi and Igralishte, the WSAs correlated with the β-glucosidase known to hydrolyze organic carbon compounds in soil. The information obtained is important for soil quality monitoring under climatic and anthropogenic changes. Full article

Aedes aegypti, the main urban vector of dengue fever, represents a growing public health problem in Nouakchott, the capital of Mauritania. Identifying the factors influencing the distribution and productivity of its breeding sites is essential for the development of effective control strategies. From May 2023 to April 2024, physico-chemical characteristics were recorded and mosquito larvae were collected, using a standard dipping method, from 60 water collections each month during the dry season and twice a month during the rainy season, totaling 294 observations. The larval positivity of water collections and larval abundance of breeding sites over the time were modeled using a random-effect logistic regression model and a negative binomial regression model, respectively. The depth, distance from habitat, type of water collection and exposure to sunlight were statistically significant and independently associated with water collection positivity for Ae. aegypti larvae (aOR = 5.18, 95%CI [1.66–16.18], p-value = 0.005; aOR = 0.00, 95%CI [0.00–0.02], p-value < 0.001; aOR = 252.88, 95%CI [4.05–15,786.84], p-value = 0.009 and aOR = 0.04, 95%CI [0.01–0.26], p-value < 0.001, respectively). Aedes aegypti larval habitats were mainly artificial (90%), temporary (n = 217 observations), close to dwellings (n = 114) and shaded (n = 96). Plastic water tanks (n = 17, 48.6%), wells (n = 6, 17.1%) and barrels (n = 4, 11.4%) were the most common breeding sites. Larval abundance was negatively associated with containers of increasing pH and surface area (aOR = 0.50, 95%CI [0.33–0.75] p-value = 0.001 and aOR = 0.48, 95%CI [0.27–0.87], p-value = 0.016, respectively). As Ae. aegypti mosquitoes are multi-resistant to adult insecticides and dengue has become endemo-epidemic since 2014, vector control should give the priority to the physical removal or treatment of shaded, peridomestic containers—particularly plastic water tanks and barrels—and consider the use of biological larvicides to target breeding sites with low pH and small surface areas. Full article

Urbanization changes the environment through physical constructions, disturbances, and altered resource availability. These modifications influence both prey and predator assemblages. Several studies have indicated that hole-nesting birds outnumber ground nesters in cities. Differential nest predation can be one reason behind this observation. We conducted a multi-year artificial nest predation experiment along an urban gradient by using artificial ground nests and nestboxes in Rovaniemi, Finland. Because visually searching avian predators dominate in cities, we predicted that nest predation of ground nests will increase with urbanization, whereas nests in holes will be better protected than ground nests. Ground nest predation increased with urbanization, being lowest in forest and rural areas, intermediate in suburban area and highest in urban area. However, there was no year-effects on artificial ground nest predation, suggesting that even a single-year results of artificial nest predation experiment can be reliable. In the city, ground nest predation was greater than nestbox predation. In forests, nestbox predation was greater than ground nest predation. Among ground nests, predation was greater in the city than in forests. Among nestboxes, predation was greater in forest than in urban or suburban habitats. Only the ground nest predation was greater in managed than in un-managed parks. Ground nest predation decreased with tree cover and increased with the patch area. No variables were entered in the models of the nestboxes. The results indicated that ground nesters might avoid urban areas as nesting sites. We assume that visually searching avian predators benefit from the lack of covering vegetation in city parks. However, because most avian nest predators, like corvids, are not effective nest predators of hole-nesting birds, urban areas are safe nesting areas for hole-nesters. The results suggest that nest predation is one important factor that could explain, why hole-nesting bird species outnumbered ground-nesting species in cities. The result give support for the hypothesis that nest predation pressure can modify urban bird assemblage structure. Full article

The impact of agricultural practices and changes in land use on soil microarthropod communities was investigated by analyzing the data from 53 sample sites with five different land-use categories (natural habitats, orchards, arable crops, olive groves and vineyards). These datasets are a mix of published and unpublished studies and were analyzed using statistical techniques that enabled a determination and comparison of the values of the biological soil quality index for each of the five land-use systems based on the richness and community composition of the biological forms of the microarthropods identified (QBS-ar), and the chemical and physical properties of the soil [e.g., pH, soil organic carbon (SOC), dominant particle sizes present (e.g., clay) and texture] for each locality. Our results confirm that different agricultural practices diminish, in different ways, the dominance and variety of species present in soil microarthropod communities. Furthermore, these agroecosystem communities represent a sub-sample of the soil microarthropod communities found in natural habitats; presumably due to the stress factors experienced from impact(s) of the differing chemical and physical properties of the soils, and the resultant selection pressures placed upon the biological forms present in the soil. Full article

Soil represents a fundamental yet delicate ecosystem susceptible to threats and alterations that can significantly impact its biota, especially in urban areas. Soil microarthropods may serve as bioindicators of soil quality. The aim of this study was to provide a comprehensive investigation of the response of soil microarthropod communities to anthropogenic pressures and to assess the biological quality of the soil in urban Rome (Italy). Microarthropods were extracted from soil samples collected at 16 sites, representing four distinct land-use types (disturbed unmanaged green spaces, disturbed managed green spaces, urban forests, and natural forests as reference) along a disturbance gradient. The basic soil properties and landscape characteristics were measured at each sampling site. Values of community diversity (calculated as Hill’s numbers based on biological forms reflecting specialization to the edaphic life), total microarthropod density, and soil biological quality indices based on microarthropod biological forms (QBS-ar and its variation QBS-ab, which also considers group abundances), were calculated for each sampling site and compared among land-use types. Land-use types varied in soil chemo-physical characteristics, with soils of managed and unmanaged green spaces being more alkaline, sodic, and compacted, and with lower organic matter, carbon, and nitrogen levels compared to urban and natural forests. Microarthropod diversity decreased from semi-natural or natural forests to highly disturbed urban sites. QBS-ar and QBS-ab values significantly differed among almost all land-use types, with managed urban green spaces exhibiting lower values than the unmanaged ones. No significant differences were observed between urban and natural forests. Soil pH, soil compaction, cation exchange capacity, C/N ratio, and vegetation cover appeared to be the most significant factors influencing the diversity and composition of microarthropod biological forms, as well as the QBS-ar and QBS-ab indices. Although with the limit of using biological forms instead of species, our investigation reaffirmed the valuable role of large, forested patches within cities for soil conservation and the preservation of their microarthropod communities. The potential of green spaces as suitable habitats for soil microarthropods should be carefully considered in urban management plans. Full article

The Brazilian Forest Code regulates Permanent Preservation Areas (PPA) and Legal Reserves (LR) across all federative states. These areas support the maintenance of ecological functions and are essential for biodiversity conservation and environmental balance. However, implementing these initiatives faces significant challenges, particularly in supporting the expansion of agribusiness. Effective management is essential for economic development while also preserving natural habitats. Our study relies on data from the Rural Environmental Registry (RER), managed by the Brazilian Federal Government, to assess PPA and LR in São Paulo. We apply the geometric metrics of the Circularity Index, Edge Factor, Fractal Dimension, and Compactness Index to evaluate these protected areas’ shape and physical characteristics, individually and as groups. The results underscore the relationship between the morphology of these areas and their ecological functions, including their susceptibility to edge effects and habitat degradation. Moreover, the large-scale analysis correlating several areas revealed the complexity of these landscapes, characterized by differing degrees of connectivity, vulnerability, and ecological efficiency, while assessing 645 districts. In conclusion, the results provide a framework for implementing protected areas that support ecosystem management and biodiversity conservation, particularly for enhancing agricultural productivity. Full article

Many grasslands around the world are affected by shrub encroachment. The essence of shrub encroachment into a grassland habitat is a change in the direction and intensity of shrub–grass interactions, which leads to an alteration in the grassland community structure. Recent research progress can be summarized as encompassing the primary factors influencing shrub encroachment and the physical, biological, and chemical ways through which they affect grassland community succession and shrub–grass interactions. The purpose of this study was to explore how shrub–grass interactions and relationships change under the influence of various environmental factors and their impact on grassland communities to provide a theoretical basis for grassland restoration and the management of shrubs within grassland from the perspective of shrub–grass interaction. Full article

Thermomineral springs are unique aquatic habitats characterized by high temperatures or mineral-rich water and often host specialized microbial communities. In Serbia, these springs represent an important but under-researched ecological resource whose diverse physicochemical properties are shaped by their geological context. In this study, the physical and chemical properties of Serbian thermomineral springs and their relationship with phototrophic communities in different substrates are investigated. Phototrophic biofilms were categorized into fully submerged and splash zone biofilms, with the former showing higher primary production. Cyanobacteria, Chlorophyta, and Bacillariophyta were recorded, with Bacillariophyta being the predominant division in terms of diversity, followed by Cyanobacteria. Among Cyanobacteria, coccoid forms like Aphanocapsa, Chroococcus, Gloeocapsa and Synechococcus dominated splash zones, while trichal forms such as Leptolyngbya, Oscillatoria and Pseudanabaena were abundant in submerged biofilms, forming thick mats. Unique cyanobacterial taxa, including Desertifilum, Elainella, Geitlerinema, Nodosilinea and Wilmottia, were identified through molecular analysis, underscoring the springs’ potential as habitats for specialized phototrophs. Diatom communities, dominated by Nitzschia and Navicula, exhibited site-specific species influenced by microenvironmental parameters. Statistical analysis revealed ammonia, total nitrogen, and organic carbon as key factors shaping community composition. This study enhances the understanding of these ecosystems, emphasizing their conservation importance and potential for biotechnological applications. Full article

This study investigated the spatial and temporal variations of macrobenthos community structure in the Yuqu River Basin during the dry and wet seasons due to environmental factors. This study quantified the independent and interactive contributions of hydrophysical, hydrochemical, and climatic factors to the community structure through a variance decomposition analysis (VPA). The study findings indicate that during May (the dry season), factors such as water depth, flow velocity, dissolved oxygen, and air temperature exhibit relatively minor fluctuations, rendering the aquatic environment more stable than in the rainy season. This stability is particularly conducive to the maintenance of the macrobenthic community structure and species diversity, which is especially evident in aquatic insects with nesting habits, such as those belonging to the Trichoptera order (including genera like Glossosoma, Glossosomatidae, and Georodes). In contrast, during August (the rainy season), substantial precipitation alters the thermal conditions of the river, increases flow velocity, raises water levels, and introduces a significant influx of organic matter through sedimentation. This distinctive ecological environment fosters unique adaptive strategies among macrobenthic organisms. Notwithstanding a notable decline in species diversity during this particular phase, there is a concurrent increase in the abundance of individual organisms, which is indicative of the populations’ remarkable capacity to swiftly adapt to environmental heterogeneity. Research has demonstrated that macrobenthic communities within the Yuqu River Basin adopt pronounced adaptive tactics that vary significantly between seasons. During the dry season, these macrobenthic fauna rely heavily on the stability of their physical habitat. In stark contrast, they are compelled to navigate and cope with the more intricate and dynamic changes in hydrological and chemical conditions that characterize the rainy season. The presented results uncover the sensitive responsiveness of the macrobenthic fauna to seasonal hydrological and environmental fluctuations in high-altitude river systems and their adaptive strategies under diverse ecological stressors. Arthropods, in particular, exhibit a marked sensitivity to seasonal hydrological and environmental changes. This study delves into the biodiversity of high-altitude river ecosystems, analyzing the ecological environment and the distribution patterns and seasonal variation characteristics of macrobenthic communities. This study aims to examine how diverse seasons and hydroclimatic conditions modulate the composition of macrobenthic assemblages within the tributaries and principal channels of high-altitude river systems, thereby establishing a foundational reference for future water ecosystem assessments in such regions. Full article

The Gambia’s coastline, known for its unique ecosystems and vital role in the country’s economy through fisheries, tourism, and agriculture, is becoming increasingly vulnerable as a result of the combined effects of climate change and human activity. This coastline sustains an important portion of the population by providing livelihoods and contributing to food security, as well as housing critical infrastructure including ports, urban areas, and tourism hubs. However, as climate change intensifies pre-existing vulnerabilities, such as increased sea-level rise, coastal erosion, and extreme weather events, these socio-economic assets are becoming more and more vulnerable. As a result, this study focused on investigating the physical vulnerability of the coastline in the context of climate change. The vulnerability assessment was conducted using the coastal vulnerability index approach, utilising a combination of oceanographic data, remote sensing, and field observations. The research outcomes supported the identification of key areas at risk and examined the contributing factors such as tidal ranges, storm surges, and human activities. The findings highlight the immediate and long-term threats to coastal communities, infrastructure, and natural habitats. Due to the vulnerability provided by geological and geomorphological factors, the average Coastal Vulnerability Index (CVI) score of 29 indicates a high level of exposure to coastal hazards from Buniadu Point to Barra. From Banjul to Cape Point, the average coastline dynamic rate is positive at 0.21 m/year, indicating some accretion. Despite this, the CVI score of 22 indicates significant vulnerability to coastal hazards from Bald Cape to Salifor Point. The study also explored potential mitigation and adaptation strategies to enhance coastal resilience to sea-level rise, coastal erosion, and flooding. Integrated and sustainable strategies were outlined to support policy-making and community-based initiatives towards safeguarding coastal regions of The Gambia against the backdrop of climate change. Full article

Tributaries flowing naturally play an important role in maintaining the biodiversity of aquatic organisms in dammed rivers. The Chishui River is currently the only undeveloped first-level tributary and an important habitat for aquatic organisms in the upper reaches of the Yangtze River. Understanding the distribution of the community structure of macrobenthos in the Chishui River and its influencing factors is crucial for the conservation and restoration of aquatic biodiversity in both the Chishui River and the Yangtze River. This study analyzes the community structure characteristics of macrobenthos in the Chishui River using four indicators, i.e., Margalef richness index, EPT taxon richness (the number of taxa in the pollution-sensitive Ephemeroptera, Plecoptera, and Trichoptera), Simpson dominance index, and Shannon diversity index, examining differences among different types of environmental factors (physical, chemical, and biological) in the upper, middle, and lower reaches. Subsequently, RDA (Redundancy Analysis) is used to analyze the main influencing factors of different types of environmental factors on macrobenthic community structure. VPA (Variance Partitioning Analysis) is employed to assess the relative importance of different types of environmental factors and their joint effects on the characteristics of macrobenthic community structure. The results indicate that physical environmental factors explain 68.7% of the variation in macrobenthic community structure indicators, chemical environmental factors explain 79.3%, and biological environmental factors account for 36.2%. The interaction among chemical, biological, and physical factors is the most significant explanatory variable, accounting for 41.7% of the variation in macrobenthic community structure characteristics. For EPT taxon number and Shannon diversity index, the interaction among chemical, biological, and physical factors is also the most important explanatory variable, accounting for 42.1% and 42.5% of the variation. For the Margalef richness index and Simpson dominance index, the interaction between chemical and physical factors is the most significant, accounting for 45.0% and 85.3% of the variation. Therefore, the impact of multiple environmental factors on aquatic organisms should not be overlooked, and attention should be paid to the contributions of various environmental factors in the conservation of macrobenthos in the Chishui River Basin. Full article

The characteristics of heartwood and sapwood not only reflect tree growth and site quality but also provide insights into habitat changes. This study examines the natural Populus euphratica Oliv. forest in the Arghan section of the lower Tarim River, comparing the heartwood and sapwood characteristics of P. euphratica at different distances from the river, as well as at varying trunk heights and diameters at breast height (DBH). The objective was to examine the correlation between these characteristics and the physicochemical properties of the soil to better understand the ecological response strategies of P. euphratica in arid environments. Results indicated that heartwood radius, sapwood width, sapwood area, and heartwood moisture content decreased with increasing trunk height, following the pattern: 0.3 m > 0.8 m > 1.3 m. In contrast, heartwood density increased as trunk height increased. Most of the heartwood and sapwood indicators increased with larger tree diameters. In the case of P. euphratica with a DBH of less than 45 cm, the difference in moisture content between heartwood and sapwood was not significant (p > 0.05) at heights of 0.3 m and 0.8 m. However, at a height of 1.3 m, the difference was significant (p < 0.05). Soil analysis revealed that factors such as total nitrogen, available potassium, and water content significantly influenced the physical characteristics of P. euphratica heartwood and sapwood across different sites. Redundancy analysis (RDA) further demonstrated that total nitrogen, available phosphorus, and soil moisture were significantly correlated with the physical properties of P. euphratica heartwood and sapwood, further validating the critical role of soil nutrients in shaping the wood characteristics of P. euphratica. These findings highlighted the specific adaptations of P. euphratica in the lower Tarim River to the arid desert environment, reflected in the observed relationships between soil conditions and the physical characteristics of heartwood and sapwood. Full article