Search Results (98)

Rice intensification influences soil biodiversity and ecological functioning in paddy ecosystems; however, its effects on soil nematode communities across different rice production systems remain poorly understood in the Vietnamese Mekong Delta (MD). This study evaluated the effects of rice cropping practices in the MD on nematode community composition, trophic structure, functional guilds, diversity, plant-parasitic nematodes (PPN), and soil chemical properties. A total of 91 soil samples were collected from double-rice intensive (RR), triple-rice intensive (RRR), and rice–upland–rice rotational (RUR) systems. Thirty nematode genera were identified, with a total abundance showing high variability, but no significant differences among cropping systems. Community composition differed considerably among systems, with Chronogaster dominating across all systems, particularly under RRR, whereas RUR supported more dominant genera with higher abundances of Tyleptus, Mesodorylaimus, Cephalobus, and Calolaimus. RUR exhibited significantly greater genus richness, and higher abundances of fungivores, omnivores, and higher colonizer–persister groups (cp4–cp5), indicating greater soil food-web complexity and ecological stability. In contrast, RRR was characterized by bacterivore-dominated communities, and increased abundance of cp3 nematodes, suggesting simplified community structures associated with agricultural intensification. Plant-parasitic nematodes remained relatively stable across management systems, despite taxon-specific responses. Soil pH, organic matter, and nitrogen availability were strongly associated with nematode community variation. Therefore, crop diversification through rotational practices enhanced belowground biodiversity, and promoted more sustainable soil ecological functioning in intensive rice production systems. Full article

Long-term changes in land-use and water quality degradation are key pressures on riverine ecosystems, yet their effects on the functional structure of fish assemblages remain insufficiently quantified. We conducted a decadal assessment of fish assemblages in four rivers experiencing rapid land-use transformation in Guangxi, China—the Zuojiang (ZY), Youjiang (YJ), Yujiang (YuJ), and Guijiang (GJ) rivers. Species-level functional traits describing body shape, vertical habitat position, feeding guild, trophic level, and maximum total length were used to calculate multiple functional diversity indices related to environmental variables using redundancy analysis and random forest models. Over the decade from 2013 to 2023, impervious surface and bare land increased significantly, while forest, shrubland, and grassland declined, coinciding with marked deterioration in water quality, including higher chlorophyll-a and lower dissolved oxygen concentrations (p < 0.05). Fish abundance and species richness decreased, and formerly dominant benthic cyprinids and loaches were replaced by tolerant and invasive taxa such as Oreochromis niloticus and Tilapia zillii. NMDS and PERMANOVA indicated a significant shift in community composition between 2013 and 2023 (R² = 0.14, p < 0.001), with fish assemblages shifting toward small-bodied, pelagic, omnivorous, and laterally compressed species. Functional richness declined, whereas functional evenness and functional dispersion increased, indicating functional simplification and homogenization. Multivariate and machine learning models consistently identified increasing impervious cover and declining dissolved oxygen as the strongest predictors of these changes. Our results demonstrate that land-use intensification and water quality deterioration are associated with reduced functional integrity in Guangxi rivers and highlight the value of trait-based indicators for monitoring and managing biodiversity in rapidly urbanizing catchments. Full article

Polygonatum kingianum Coll. (PKC) is a valuable medicinal herb native to Yunnan, China, but its yield and quality are severely threatened by root rot. To elucidate the rhizosphere microbial dynamics associated with this disease and to identify location-transcending patterns, we collected rhizosphere soils from healthy and diseased PKC plants at three planting bases in Lincang, Qujing, and Kunming. Soil properties were measured, and bacterial (16S rRNA) and fungal (ITS) communities were characterized by amplicon sequencing. Geographic origin emerged as the dominant factor associated with microbial community structure, with soil moisture, organic matter, and nutrients all showing significant associations. The effect of disease on microbial diversity was site-specific. Nevertheless, LEfSe analysis identified cross-location-consistent indicator genera: Acidiferrimicrobium and HSB_OF53_F07 were enriched in healthy soils, while Burkholderia-Caballeronia-Paraburkholderia and Rhodanobacter were enriched in diseased samples. At the trophic mode level, a consistent pattern was observed: diseased rhizosphere soils had higher relative abundance of pathotrophic fungi and lower abundance of symbiotrophic fungi compared to healthy soils. However, at the finer guild level, no individual guild showed statistically significant differences after FDR correction. Co-occurrence network analysis revealed a striking structural reorganization: healthy plants harbored a fungus-dominated network (57.04% fungi), whereas diseased plants shifted to a bacterium-dominated network (55.71% bacteria), accompanied by an increased proportion of negative correlations. Redundancy analysis (RDA) and Mantel tests further confirmed that soil physicochemical properties, rather than health status, were the primary factors associated with microbial community variation (Mantel’s r = 0.725 for bacteria, 0.768 for fungi). Collectively, this study provides the first systematic evidence of cross-location common microbial shifts and network reorganization associated with PKC root rot. These findings offer a microecological basis for developing green prevention and control strategies against this devastating disease. Full article

Seasonal hydrology reshapes large-river food webs by altering habitat connectivity and basal resource availability. Trophic baselines from before the 2021 Yangtze ten-year fishing ban are now valuable because monitoring has shifted from fish abundance alone toward food-web function and ecological recovery. We analysed carbon (δ¹³C) and nitrogen (δ¹⁵N) stable isotopes of fish and the baseline bivalve Corbicula fluminea collected in March (dry season) and August (wet season) 2016 from the Jingjiang section of the lower Yangtze River. In the dry season, 100 individuals of 27 species were analysed; species mean δ¹³C ranged from −30.52‰ (Micropercops swinhonis) to −21.19‰ (Aristichthys nobilis) and δ¹⁵N from 6.30‰ (Hypophthalmichthys molitrix) to 14.90‰ (Lophiogobius ocellicauda). In the wet season, 187 individuals of 47 species were analysed; species mean δ¹³C ranged from −32.07‰ (Pseudobrama simoni) to −20.84‰ (Salanx ariakensis) and δ¹⁵N from 6.27‰ (Misgurnus anguillicaudatus) to 14.87‰ (Saurogobio gymnocheilus). Among 24 shared species, δ¹³C differed significantly between seasons (paired t = 4.30, p < 0.001), but δ¹⁵N did not (t = 1.52, p = 0.143). Mean trophic level fell from 3.07 to 2.74 (t = 3.85, p < 0.001). This decline remained significant in a trophic-enrichment-factor sensitivity analysis using 2.5–4.0‰. Community-wide carbon range (CR), nitrogen range (NR), total convex-hull area (TA), mean nearest-neighbour distance (NND), and the standard deviation of nearest-neighbour distance (SDNND) showed larger wet-season CR (9.08 vs. 7.51), slightly larger NR, TA and NND, and lower SDNND. Seasonal hydrology thus mainly altered basal carbon pathways and relative trophic positions rather than reorganising feeding guilds. The dataset provides a pre-ban isotopic baseline for assessing whether post-ban recovery in the lower Yangtze includes restoration of trophic structure and energy-flow pathways. Full article

Canker is a major fungal disease that causes substantial yield losses in pitaya (Selenicereus monacanthus (Lemaire) D.R.Hunt, syn. Hylocereus polyrhizus (F.A.C. Weber) Britton and Rose; red-fleshed pitaya). However, how fruit ripening and pathogenesis interactively shape fungal communities in fruit peels remains unclear. Here, we investigated the diversity, assembly mechanisms, co-occurrence networks, and functional guilds of fungal communities in healthy and diseased fruit peels at immature (green) and mature (red) stages of ‘Jindu No. 1’ pitaya using ITS1 amplicon sequencing. Our results revealed that fruit maturity exerted stronger effects on fungal community structure than disease status, with ripening reducing diversity and increasing dominance. Notably, disease-induced stage-dependent responses: immature communities shifted from stochastic to deterministic assembly under pathogen selection, whereas mature communities maintained stochastic processes despite infection. Co-occurrence network analysis revealed that healthy mature peels formed highly complex, cooperative networks with dense positive interactions, while healthy immature peels exhibited fragmented, modular structures vulnerable to invasion. Diseased immature peels displayed intermediate network topology, and diseased mature peels showed disrupted connectivity. Functionally, healthy fruits maintained balanced pathotroph-saprotroph-symbiotroph guilds, whereas diseased fruits exhibited higher relative abundance of pathotrophs and saprotrophs, reflecting a shift from symbiotic nutrient cycling toward necrotrophic pathogenicity and decomposition. These findings challenge the single-pathogen paradigm by revealing canker as an ecological process involving community-wide restructuring. They provide a theoretical basis for stage-specific microbiome-targeted disease management in tropical fruits, emphasizing the preservation of stochastic assembly and cooperative network structures to enhance disease resistance. Full article

Environmental gradients associated with continentality shape terrestrial ecosystems by modifying biodiversity patterns, community structure, and ecosystem functioning. In arid ecosystems, where water and thermal constraints are pronounced, soil organisms represent sensitive indicators of environmental change. Soil nematodes, due to their functional diversity encompassing bacterivores, fungivores, herbivores, omnivores, and predators, constitute effective bioindicators of soil health. We hypothesized that increasing continentality (thermal amplitude) would progressively reduce nematode diversity and functional complexity while altering CUE and metabolic footprints through community compositional shifts. A total of 130 soil samples were collected across three bioclimatic zones (island, coastal, and semi-continental) within the Arganeraie Biosphere Reserve, Morocco, and analyzed for nematode abundance, diversity, trophic structure, ecological indices, and functional traits. Nematode abundance and richness were significantly higher in the island zone compared to the coastal and semi-continental zones, while Shannon diversity did not differ significantly. The island zone exhibited a balanced trophic structure with higher proportions of bacteribores, fungivores, herbivores, and omnivores–predators, than the coastal and semi-continental zones. CUE values were consistently low (<0.5) across all zones, with the widest distribution in the island zone. Thermal amplitude was negatively associated with nematode biomass (R = −0.36), production (R = −0.27), and all trophic footprints, with herbivores showing the steepest decline (R = −0.51). Notably, total energy flux remained relatively stable despite reductions in diversity and trophic complexity, suggesting functional redundancy within dominant bacterivore guilds. These findings support the hypothesis that increasing continentality is associated with reduced nematode diversity and functional complexity, alongside altered carbon processing efficiency. This study underscores the value of integrating trophic, metabolic, and energetic approaches for assessing soil health vulnerability in Mediterranean agroecosystems under climate change. Full article

Urban aquatic ecosystems are increasingly shaped by anthropogenic pressures that alter community structure and ecological functioning. This study investigates how the functional organization of zooplankton communities reflects ecosystem stability along an urbanization gradient in the Colentina River–Lake system (Romania). Zooplankton taxa were classified into trophic guilds and size-based functional groups, and functional diversity was quantified using the FEve, FDiv, FDis, and RaoQ indices, based on functional trait structure and distribution within communities. Ecosystem stability patterns were estimated through zooplankton community resilience (RSL) and resistance (RST), indices derived from Shannon diversity and Pielou evenness. Across the system, filter feeders dominated, and their density increased toward downstream, highly urbanized sectors. Also, small-sized organisms (SMC) were consistently prevalent, representing a zooplankton component commonly associated with stress tolerance and opportunism in disturbed aquatic environments. Functional diversity patterns showed low evenness but high divergence, suggesting that although few functional strategies dominate, communities maintain internal differentiation. While filter feeders remained dominant even in disturbed sectors, the uneven distribution of other groups, especially scrapers, may reflect greater sensitivity to anthropogenic conditions. These findings suggest that functional trait composition, in addition to diversity, plays an important role in shaping structural stability patterns. These findings indicate that functional trait composition, in addition to diversity, was associated with the observed stability patterns. The study reinforces the value of zooplankton as sensitive indicators of functional integrity in anthropogenically impacted freshwater systems and provides insights relevant for sustainable urban water management. Full article

Microplastic (MP) contamination is an emerging threat to aquatic ecosystems. However, species-specific bioaccumulation patterns across trophic guilds in tropical river ecosystems remain scarcely understood. This study assessed the occurrence, organ-level distribution, polymer composition, and ecological risk of MPs in 220 fish representing 12 species, spanning across multiple trophic guilds, sampled from four sites along a pollution gradient of the river Yamuna, India. MPs were detected in all examined species, confirming extensive distribution across the river ecosystem. A total 1678 MPs were recovered, with significantly higher abundance in fish from the highly urban Delhi stretch than in those from upstream regions (Kruskal–Wallis, H = 11.03, p = 0.011). The highest species-specific MP load was recorded in omnivorous Oreochromis niloticus from Sonia Vihar (436 MPs), whereas the carnivorous species Xenentodon cancila exhibited the lowest accumulation (37 MPs). Surface- and mid-water herbivores and omnivores accumulated more MPs than benthic carnivores and detritivores. Nonetheless, spatial pollution gradients exerted a stronger influence on MP accumulation, compared to trophic guilds. The gastrointestinal tract exhibited the highest MP abundance (751 MP particles), followed by gills (605) and muscle tissues (322), confirming ingestion as primary uptake route, and suggesting possible tissue translocation. Fibers dominated in the assemblage (77.8%), while transparent (44%) and blue (19.5%) were most abundant colors. ATR–FTIR analysis confirmed 10 diverse polymers, with polyethylene (≈24%) and polypropylene (≈21%) together accounting for nearly half of the identified particles. The Polymer Hazard Index analysis classified the recovered MP mix as Category IV (high ecological hazard). These findings identify the Delhi stretch of the Yamuna as a high MP contamination zone and highlight the combined influence of urban pollution and fish ecology on MP bioaccumulation. Full article

Urbanization can act as a powerful ecological filter, restructuring biodiversity through species loss, replacement, and altered resource pathways. While urban green spaces (UGS) are recognized as potential biodiversity refuges, the effectiveness and mechanisms for conserving insect diversity across the urban-to-natural gradient remain poorly understood. Here, we combine full-season Malaise trapping (April–November) with MinION-based DNA barcoding to test two predictions about how urbanization reshapes Diptera communities across five sites in Haidian District, Beijing, ranging from residential areas and urban parks to a nearby shallow mountain reserve (BWM). Based on 5528 barcoded individuals, we identified 686 putative species from 39 families. As predicted, β-diversity between urban and mountain sites was overwhelmingly driven by species turnover rather than nestedness, demonstrating that cities do not simply receive subsets of the surrounding fauna but actively reassemble communities. This filtering effect was, however, trophic-guild specific. Detritivores showed the highest replacement, consistent with a shift from natural to anthropogenic resource subsidies, while predators/parasitoids exhibited significant nested loss, aligning with their hypothesized sensitivity at higher trophic levels. Vegetation structure further clarified these patterns: vegetation density, not plant species richness, was the primary bottom-up driver for herbivore and predator/parasitoid diversity, whereas detritivores were decoupled from living plant biomass. These findings demonstrate that urban and near-natural habitats maintain distinct species pools via guild-specific assembly pathways, highlighting the need for guild-specific conservation strategies for urban biodiversity conservation. Extending beyond compositional analysis, we propose a temporal-abundance framework, classifying species by persistence and abundance, as a diagnostic tool for assessing ecological integrity and guiding conservation in urbanizing landscapes. Full article

Background: Soil degradation in intensive tea plantations necessitates sustainable management. Straw application (S) is a promising practice, yet its integrated effects on soil fungal communities in acidic tea soils require comprehensive evaluation. Methods: High-throughput sequencing based on the primers of fungal ITS1F-ITS2 was conducted on soils from tea plantations with/without straw application (S and CK, respectively). Analyses encompassed community structure, α- and β-diversity, differential taxa, co-occurrence networks, the main drivers by soil properties, and functional prediction. Results: The core fungal community structure except for Basidiomycota, and diversity remained stable under S. However, 17 ASVs responded as significant biomarkers, including fine-scale shifts within the genus Sebacina. S modified the complexity of the fungal co-occurrence network with enhancing its modularity and integration and increasing keystone connectors, while overall network cohesion was maintained. Soil available phosphorus (AP), soil organic matter (SOM) and nitrate nitrogen (NO₃⁻-N) were the dominant drivers of fungal amplicon sequence variants (ASVs), with water content (WC) the main driver of fungal keystones. Functionally, S selectively affects the richness of Symbiotrophs (including endophytes) without altering the relative abundance structure of major trophic guilds. Conclusions: S acts as a modulator, refining fungal network architecture and interactions within the resilience threshold of the community, offering a viable practice for sustainable tea soil management. Full article

Mixed plantations of Pinus sylvestris var. mongolica with native shrubs are widely established in semiarid sandy landscapes, yet soil microbial responses may differ among mixed-planting modes depending on the companion shrub species. We compared soil bacterial and fungal communities across three approximately 9-year-old mixed-planting modes in the Mu Us Sandy Land, where P. sylvestris var. mongolica was combined with Juniperus sabina (Ps–Js), Salix psammophila (Ps–Sp), or Corethrodendron fruticosum (Ps–Cf). Planting configuration was associated with shifts in soil physicochemical conditions. Bacterial α-diversity did not differ among modes, whereas fungal α-diversity was higher in Ps–Sp. Community composition diverged across modes for both domains, and LEfSe identified configuration-specific taxa. Null-model analyses showed that bacterial assembly was consistently dominated by stochastic components, whereas the relative contributions of fungal assembly processes varied among mixed-planting modes. Functional inference further suggested mode-associated differences in fungal trophic guild composition, with Ps–Cf showing significantly higher ectomycorrhizal abundance and Ps–Sp showing higher representation of saprotroph-associated guilds; by contrast, predicted bacterial functional profiles were broadly comparable among modes. Together, these results indicate that bacterial and fungal communities showed different response patterns among mixed-planting modes: bacterial communities showed compositional differentiation but little variation in α-diversity and consistently stochastic assembly, whereas fungal communities showed mode-related changes in α-diversity, the relative contributions of assembly processes, and trophic guild composition. These findings provide a microbial basis for considering shrub-species selection when designing P. sylvestris var. mongolica mixed plantations in semiarid sandy ecosystems. Full article

Although sedimentary zones in Lake Taihu differ in external inputs, hydrodynamic conditions, and sedimentary settings, the spatial differentiation of eukaryotic microbial communities and their assembly mechanisms remain insufficiently understood. This study analyzed sediment cores from four typical sedimentary zones of Lake Taihu: Dapu (DP), Gonghu (GH), the central lake area (HX), and Xuhu (XH). By integrating physicochemical measurements, 18S rRNA gene high-throughput sequencing, redundancy analysis, functional annotation, iCAMP, and co-occurrence network analysis, we characterized the composition, environmental associations, and assembly mechanisms of sedimentary eukaryotic microbial communities. The results showed that eukaryotic microbial communities in Lake Taihu sediments exhibited marked spatial heterogeneity, with dominant taxonomic groups including Chlorophyta, Intramacronucleata, and Diatomea. Alpha diversity was higher in the GH zone and lower in the HX zone, whereas beta diversity showed significant separation among lake zones. NH₄⁺-N, NO₃⁻-N, TN, TP, TOC, D50, MWC, and pH were associated with variation in community composition, but the main associated factors differed among zones. FunGuild annotation showed that annotated fungal functional groups exhibited distinct trophic distribution patterns across sedimentary zones. iCAMP analysis indicated that community assembly was generally dominated by stochastic processes, with dispersal limitation prevailing in the GH zone and ecological drift dominating in the DP, HX, and XH zones. Co-occurrence network analysis further revealed marked differentiation in potential biological associations among sedimentary zones. Overall, this study showed that nutrient conditions and sediment physical properties in different sedimentary environments of Lake Taihu jointly shaped the spatial patterns of eukaryotic microbial communities and their ecological associations, providing baseline information for understanding sedimentary ecological processes in eutrophic shallow lakes. Full article

The global expansion of tree plantations has led to extensive fragmentation of natural forests, posing significant challenges for biodiversity conservation. Understanding the diversity patterns and underlying mechanisms of ground-dwelling insects in these fragmented landscapes is critical to inform effective conservation strategies. To address this, we sampled ground-dwelling insects using pitfall traps across nine remnant natural forest fragments (“islands”) embedded within a tree plantation matrix in Guangxi, China. We examined insect family-level diversity and community composition in relation to fragment isolation (low vs. high) and size (large vs. small) and explored the mechanisms driving the observed patterns. Our results revealed no significant difference in ground-dwelling insect diversity between low-isolation and high-isolation fragments. However, diversity was significantly lower in smaller fragments compared to larger ones. This reduction was primarily driven by decreased seedling density within smaller fragments, directly reflecting the adverse effects of plantation-driven fragmentation on native seedling establishment. Furthermore, we observed noble shifts in community composition of ground-dwelling insects along both fragment isolation and size gradients. Highly isolated fragments exhibited a decline in phytophagous insects and omnivores (with detritivore-herbivore diets), but an increase in detritivores. Smaller fragments exhibited consistent declines across multiple insect taxa spanning various dietary guilds. The observed changes in ground-dwelling insect composition were driven by shifts in plant (especially seedling) community composition. Our findings reveal a clear cascading effect: plantation-driven fragmentation limits native plant regeneration, and these limitations subsequently propagate to higher trophic levels, profoundly impacting ground-dwelling insects. Effective restoration of plantation-fragmented landscapes requires strategies that both prioritize the preservation of large, continuous forest fragments and promote native seedling recruitment within existing fragments. Full article

Marine fungi are pivotal components of coastal ecosystems, facilitating essential biogeochemical cycling and trophic dynamics. However, the complex mechanisms governing their spatiotemporal community patterns in tropical–subtropical coasts remain largely unexplored. In this study, we characterized marine fungal diversity across a comprehensive seasonal cycle (spring (March), summer (June), autumn (August), and winter (December)) at 21 representative sites along the Leizhou Peninsula, China. These sites were strategically selected to encompass a broad range of dissolved inorganic nitrogen (DIN) gradients. Fungal community composition was characterized via high-throughput sequencing of the internal transcribed spacer 2 (ITS2) region, followed by functional guild profiling using the FUNGuild database. A total of 8777 amplicon sequence variants (ASVs) were identified, encompassing a broad taxonomic breadth of 10 phyla and 358 genera. Ascomycota, Basidiomycota, and Chytridiomycota emerged as the predominant phyla across all samples. Our results revealed significant spatiotemporal heterogeneities: seasonal succession fundamentally reshaped community composition, with DIN exerting its most pronounced influence during the winter. Furthermore, fungal functional structures exhibited distinctive clustering across regions defined by DIN enrichment levels. Co-occurrence network analysis revealed a highly modular and robust architecture, characterized by predominantly positive interactions and dense inter-taxon connectivity. These findings underscore the synergistic influence of temporal dynamics and DIN enrichment in shaping marine fungal community assembly and functional compositions. Our study provides critical baseline insights into the ecological resilience of coastal mycobiota in the South China Sea. Full article

We compared fish assemblage structure and total mercury (THg) bioaccumulation between a natural floodplain lake and a constructed irrigation canal in central Brazil. A total of 473 individuals representing 34 species were recorded, and dorsal muscle samples from 62 specimens representing shared species or species occupying comparable trophic positions were analyzed for THg (Curimatella immaculata, Hemiodus microlepis, Astyanax aff. bimaculatus, Triportheus albus, Geophagus sveni, Pimelodus blochii, Pygocentrus nattereri, Lycengraulis batesii, and Cichla kelberi). The floodplain lake exhibited higher species richness, diversity, and evenness, whereas the irrigation canal supported a simplified assemblage dominated by fewer species. Total Hg concentrations were significantly higher in the lake than in the irrigation canal; however, this pattern was observed only for the carnivorous guild (t = 5.384, p < 0.0001) and the detritivorous guild (t = 4.183, p = 0.0001). THg increased significantly with trophic level in both systems, from detritivores to carnivores (F₂,₄ = 15.127, p = 0.009), yielding comparable trophic magnification slopes (lake: 1.46, 95% CI: 1.11–1.81; canal: 1.36, 95% CI: 0.94–1.77). Despite lower diversity and THg concentrations in the irrigation canal, Hg transfer efficiency across trophic levels was conserved between systems. Full article