Web Structure Research Articles

Benefit and risk: Keystone biomes in maize rhizosphere associated with crop yield under different fertilizations

The highly diverse beneficial and deleterious microbes in the rhizosphere influence plant growth and crop production in agricultural ecosystems. However, our understanding of the relationships between beneficial and risky phylotypes in the rhizosphere, and plant growth, in addition to their potentially varied response to different fertilization treatments in black soils, remains poor. Here, we investigated variations in multitrophic (e.g., bacteria, fungi, invertebrates, and protists) community composition and diversity under different five-year fertilization treatments, and identified the potential beneficial and potential risky keystone multitrophic biota in maize rhizosphere and bulk soils based on ecological networks and soil food web structure. Bacteria and protist community compositions exhibited greater variations under different fertilization regimes when compared with those of fungi and invertebrates. In addition, two keystone phylotype groups associated with crop yield and soil function were detected, and the potential beneficial keystone phylotypes exhibited higher relative abundances in C-fixation, N-fixation, and P-mineralization genes; conversely, the potential risky keystone phylotypes were associated with denitrification and nitrate reduction genes, and included more potential fungal pathogens. Furthermore, structural equation modeling results indicated that organic amendments, particularly cow manure, could improve crop yield by enriching beneficial keystone phylotypes and suppressing risky keystone phylotypes. Altogether, the results of the present study highlight the critical roles of rhizosphere biota in food production, and identify keystone phylotypes that are beneficial or harmful to crop production and soil function, which could facilitate the conservation of beneficial biota and the early detection of potential pathogens, as well as the exploitation of beneficial biota to increase crop yield.

Investigating the Influence of Anthropogenic Activities on Behavioral Changes of an Orb Web Spider (Neoscona vigilans).

Orb web spiders are common and highly diversified animals found in almost all habitats. They have remarkable plasticity against biotic and abiotic factors, making them excellent indicators of environmental health. The web creation behavior of spiders is influenced by disturbances in the environment. The aim of this research was to observe the alteration in the web-building behavior of Neoscona vigilans caused by human activities, specifically traffic disturbances. Spider webs were located and photographed at nighttime along the roadside, and their web characteristics were calculated. Spiders were captured from webs for their body measurements. Spider fourth leg length, carapace width, and body length had a significant association with web size and diameter, CTL, capture area, and mesh size. The quantity of trapped prey, the height of the plant, and the foliage radius increased with the distance from the road. Conversely, anchor points and web elevation from the ground dropped. The highest and lowest proportions of anomalies (modifications/defects) were recorded as holes (52.7%) in 105 webs (100%) and supernumerary (0.7%) in 55 webs (52.4%), respectively. Road disturbance had a negative influence on the spider's behavior as the webs formed in close proximity to the road had a higher frequency of anomalies, with a gradual decrease distantly. We can gain further insight into how different environmental changes, disruptions, and pollutants lead to this imperfection in the otherwise flawless perfect structure of spider webs.

Increasing microplastic exposure had minimal effects on fatty acid composition in zooplankton and yellow perch in a large, in-lake mesocosm experiment

Using 10 m diameter mesocosms in a Canadian boreal lake, we investigated the effects of microplastic (MP) exposure on the body weight and diet of yellow perch ( Perca flavescens) and the fatty acid composition of yellow perch and zooplankton. We exposed the aquatic ecosystem within seven mesocosms for 10 weeks to a mixture of polyethylene, polystyrene, and polyethylene terephthalate fragments, ranging in nominal addition concentrations from 6 to 29 240 particles L−1 (although realized water column concentrations were lower), as well as two negative controls. Increasing MP exposure did not affect yellow perch body weight (growth) or diet, or the overall fatty acid composition of yellow perch muscle or zooplankton. Results were highly variable across mesocosms. Despite high levels of MP ingestion by yellow perch, we did not find evidence of MPs leading to food dilution or any other effect where we could anticipate impacts on food web structure.

Exploring Biodiversity and Food Webs in Sulfur Cave in the Vromoner Canyon on the Greek–Albanian Border

Sulfidic caves support diverse and abundant subterranean communities, including numerous endemic species and complex food webs, though the full extent of species diversity and resource utilization in these ecosystems remains largely unexplored. This paper presents the results of biological surveys conducted from 2023 to 2024 in Sulfur Cave, located in the Vromoner Canyon on the Greek–Albanian border, focusing on microbial, vertebrate, and invertebrate communities and investigating the structure of the subterranean food web. The microbial communities from the different biofilms are dominated by chemosynthetic sulfur-oxidizing microorganisms, specifically filamentous bacteria such as Thiotrix and Beggiatoa. Two species of fish, an eel (Anguilla sp.) and a Cyprinid (Alburnoides sp.), and six bat species from three families (Rhinolophidae, Miniopteridae, and Vespertilionidae) were documented. The invertebrate fauna includes five aquatic species, 25 terrestrial species, and four amphibiotic species. Among these, eight species are endemic, and seven species exhibit troglomorphic traits. Stable isotope analysis showed light carbon and nitrogen values for the terrestrial and aquatic invertebrates, suggesting that subterranean communities rely on food produced in situ by chemoautotrophic microorganisms. Our results identified cave areas of significant biological relevance and provided reference data to inform conservation actions aimed at preserving the biodiversity of this sulfidic cave.

Antibacterial cellulose solution-blown nonwovens modified with salicylic acid microcapsules using NMMO as solvent

Solution blowing process was used to prepare cellulose nonwovens, by using N-methyl morpholine-N-oxide (NMMO) as solvent, and salicylic acid (SA) microcapsules as antibacterial additives. The structure and properties of cellulose nonwovens modified with different SA microcapsules contents were compared and evaluated. The results showed that more uniform and denser web structure was formed with the increase of SA microcapsules content, the average fiber diameter of cellulose nonwoven increased from 1.99 μm to 2.65 μm. The air flow resistance and filtration efficiency of cellulose nonwovens increased with addition of SA microcapsules, whereas the mechanical properties, and wearing comfort including air permeability, moisture vapor transfer rate, and softness of cellulose nonwovens decreased slightly, under the same basis weight. SA microcapsules modified cellulose nonwovens exhibited good sustained-release behavior and antimicrobial activity against Escherichia coli. The higher SA microcapsules content in cellulose nonwovens, the faster release rate and the higher antimicrobial activity. The cellulose solution-blown nonwovens modified with SA microcapsules are expected to find applications in medical and healthcare fields due to its antibacterial activity and biodegradability.

Recent research progress of soil nematode ecology in China.

Soil nematodes are a crucial component of belowground ecosystems. Soil nematode ecology, the studies of community distribution, structural composition, ecological functions, and interaction mechanisms with environment, has always been a hot spot in soil biology research. We systematically elaborated soil nematodes' high diversity and various diet, their advantages as bioindicator and model organisms, and their roles in biological control, ecological functions and soil health. Then, we reviewed the research progress of soil nematode ecology in China, including molecular biology identification methods, responses to global changes, food web structure and function, aboveground and belowground diversity relationship, and large-scale diversity pattern. We put forward the development trend of soil nematology, focusing on the high-throughput sequencing technology in nematode identification and quantification, the necessity of establishing a universal analysis platform to promote soil nematode research, and the importance of strengthening large-scale soil nematode survey.

Dining in danger: Resolving adaptive fish behavior increases realism of modeled ecosystem dynamics.

Animals occupying higher trophic levels can have disproportionately large influence on ecosystem structure and functioning, owning to intricate behavioral responses to their environment, but the effects of behavioral adaptations on aquatic ecosystem dynamics are underrepresented, especially in model studies. Here, we explore how adaptive behavior of fish can affect the dynamics of aquatics ecosystems. We frame fish behavior in the context of the central trade-off between feeding and predation, calculating the optimal level of feeding determined by ambient food availability and predation risk. To explore whole-ecosystem consequences of fish behavior, we embed our behavioral model within the Water Ecosystems Tool (WET), a contemporary end-to-end aquatic ecosystem model. The principle of optimality provides a robust and mechanistic framework for representing animal behavior that is relevant for complex models, and can provide a stabilizing effect on model dynamics. The model predicts an emergent functional response similar to Holling type III, but with richer dynamics and a more rigorous theoretical foundation. We show how adaptive fish behavior works to stabilize food web dynamics compared to a control model with no optimal behavior, and how changing the strength of the underlying trade-off has profound effects on trophic control and food web structure. Furthermore, we demonstrate how including fish behavior allows for an overall more realistic response of the model system to environmental perturbation in the form of nutrient enhancement. We discuss the structuring effects of behavioral adaptations in real ecosystems, and how approaches like this one may benefit aquatic ecological modeling. Our study further highlights how a mechanistic approach based on concepts from theoretical ecology can be successfully implemented in complex operational models resulting in improved dynamics and descriptive power.

Response of soil nematode community structure and metabolic footprint to nitrogen addition in alfalfa fields on the Loess Plateau

Nematodes serve as key indicators of soil health in ecological studies. Therefore, the current study examined the community structure and metabolic footprint of soil nematodes in alfalfa fields across varying levels of N supply in the semi-arid Loess Plateau. The findings offer theoretical guidance for the sustainable management of artificial alfalfa grasslands in this region. The research was based on alfalfa fields with different N application rates (0, 50, 100, 150 kg/ha2) as the research object, The shallow plate method was used to separate and extract soil nematodes, identify soil nematode groups, calculate ecological function index and metabolic footprint, and identify indicator species. A total of 6346 nematodes were isolated in this study, belonging to 27 genera and 19 families. Notably, the plant parasitic nematode Helicotylenchus was predominant. As N addition increased, the plant parasitic index (PPI) increased significantly. A N50 application significantly enhanced the soil nematode diversity index (H\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ ext{H}$$\\end{document}) and the free-living index (MI). The findings showcased a noticeable decrease in disturbance within the N50 soil nematode community. This resulted in a mature and stable community structure primarily attributed to the heightened abundance of omnivorous/predatory nematodes. Across various N levels, soil nematode communities underwent significant alterations in the soil food web structure through shifts in their metabolic footprint. Future strategies should focus on refining N management practices and integrating sustainable approaches like crop rotation and pest management. These efforts will contribute to guidelines ensuring artificial alfalfa grasslands lasting health and productivity.

Determining key mammalian species and food web robustness across different land cover vegetation using network analysis

Abstract. Risdiyanto I, Santosa Y, Santoso N, Sunkar A. 2024. Determining key mammalian species and food web robustness across different land cover vegetation using network analysis. Biodiversitas 25: 3175-3190. The ecosystem's food web depicts the intricate energy flow and complex interactions among its diverse organisms. Organisms are not confined to single trophic levels or food chains; they establish multiple food connections with other organisms within the ecosystem. This study aims to identify critical mammalian species and assess the robustness of various ecosystem types, considering the diversity of species presence, through food web analysis. Computational graphic-based network analysis is employed to achieve this goal. Ecosystem types, categorized by their land cover, include plantation/agricultural forests, Bushes and shrubss, forests, and mixed landscapes. Network centrality metrics such as degree, closeness, betweenness, and eigenvector centrality are utilized to evaluate the presence of key species and ecosystem robustness. The relative contribution of mammalian species as connectors and regulators of energy flow in the food web ranges from 8-23% of all nodes involved. Key mammalian species are classified into ecosystem stability and sustainability keys. In Bushes and shrubss ecosystems, key species predominantly consist of mammalian predator species that are crucial for maintaining ecosystem stability through population control. Conversely, in other ecosystems, key species are primarily connectors, ensuring the sustained energy flow. The most resilient food webs are observed in Bushes and shrubss and mixed ecosystems due to their higher biomass growth rates and abundant presence of mammalian species. Utilizing food web analysis can significantly contribute to species and ecosystem conservation efforts by offering a comprehensive understanding of interspecies interactions, food web structures, and ecosystem dynamics.

Neutrophil extracellular traps as markers of infectious and aseptic inflammation

One of the important problems of medicine is the search for new reliable markers of inflammation that would allow us to determine the type of inflammatory process. The aim of the study was to identify specific markers of infectious and aseptic inflammation based on the analysis of morphological variants of neutrophil extracellular traps (NETs). The study included 26 patients with various nosological forms of inflammation in the abdominal cavity (12 with acute appendicitis, 8 with acute cholecystitis, 6 with a diagnosis of pancreatitis/ pancreonecrosis) after surgery. The study also included 20 patients with post-COVID and a group of 10 volunteers no clinical manifestations of the disease, but at the same time had contacts with flu patients. Neutrophils were isolated using gradient centrifugation. Fluorescence microscopies with the dye SYBR Green (JSC “Evrogen”, Russia) were used for NET visualization and counting. NETs in the morphological form of neutrophils web structure were found in the blood of surgical patients with acute appendicitis who had a favorable course of the postoperative period. In a group of volunteers who were exposed to influenza but did not have symptoms of an infectious disease, we also found neutrophils web structure. In all patients with abdominal inflammation complicated by abdominal abscess, in addition to neutrophil web structure, abnormal forms of NETs were recorded, in particular, NETs in the form of single filaments. In the post-COVID patients an absolute absence of neutrophilis web structure was revealed. In all post-COVID patients, NETs are found only in the form of single filaments. The results of subsequent experiments showed that collagen peptides are inducers of the formation of NETs in the form of single filaments. The detection of neutrophils web structure is a sign of an infectious inflammatory process. NETs in the morphological form of single filaments are markers of aseptic inflammation, as well as a sign of endothelial damage.

Spatially explicit predictions of food web structure from regional-level data.

Knowledge about how ecological networks vary across global scales is currently limited given the complexity of acquiring repeated spatial data for species interactions. Yet, recent developments in metawebs highlight efficient ways to first document possible interactions within regional species pools. Downscaling metawebs towards local network predictions is a promising approach to using the current data to investigate the variation of networks across space. However, issues remain in how to represent the spatial variability and uncertainty of species interactions, especially for large-scale food webs. Here, we present a probabilistic framework to downscale a metaweb based on the Canadian mammal metaweb and species occurrences from global databases. We investigated how our approach can be used to represent the variability of networks and communities between ecoregions in Canada. Species richness and interactions followed a similar latitudinal gradient across ecoregions but simultaneously identified contrasting diversity hotspots. Network motifs revealed additional areas of variation in network structure compared with species richness and number of links. Our method offers the potential to bring global predictions down to a more actionable local scale, and increases the diversity of ecological networks that can be projected in space. This article is part of the theme issue 'Connected interactions: enriching food web research by spatial and social interactions'.

Zooplankton grazing reduces the persistence of an anthropogenic pollution marker in lake water

AbstractWastewater treatment plant effluents release microbiological pollutants, including the intI1 gene (integrases of class 1 integron), which has been proposed as a target for monitoring anthropogenic pollution in surface waters. This gene correlates with antibiotic resistance genes, making it an important proxy for genetic contamination in aquatic environments. It is currently unclear whether intI1 found in lake water is mainly present due to continuous seeding or if autochthonous bacteria harbor this gene. To better understand the fate and dynamics of class 1 integrons in aquatic systems, we resorted to classical limnological monitoring of intI1 (qPCR) over multiple years in three different size fractions: free‐living bacteria, particle‐attached bacteria, and zooplankton‐attached bacteria. We also conducted experiments to elucidate the impact of grazers on the abundance of intI1. The monitoring of different size fractions of the Lake Maggiore microbial community showed a particle‐bound lifestyle for intI1‐hosting bacteria. Most of these bacteria originated from both a wastewater effluent that discharges into Lake Maggiore and the lake water itself (amplicon sequencing). We hypothesize that these bacteria grow on particles in open waters, making them particularly vulnerable to grazing by large filter feeders such as Daphnia. Therefore, the presence of Daphnia reduced the abundance of intI1 in lake water, whereas this was not true for other grazers such as Rotaria macrura or Poterioochromonas sp. Our study shows that the food web structure and temporal changes in the lake influence the abundance of intI1 and consequently the assessment of anthropogenic pollution.

Bionic design and mechanical performance of spiderweb-inspired mesh fabrics

The mesh structure is widely applied due to its unique structure and exceptional performance, especially spider web structural materials, which have attracted widespread interest. However, the existing flexible spider web structural materials face problems such as low production efficiency and structural defects, constraining their practical application. This study proposed two types of no-knot mesh fabrics according to the topological structure of spider web and explored their mechanical properties. Both knitted loop divergent and ring spiral mesh fabrics showed excellent mechanical performance, with the ring spiral fabric demonstrating higher maximum failure forces (2217 N in tensile and 5738 N in bursting tests) and superior impact performance in terms of maximum impact force and energy absorption. Both fabrics exhibited similar creep behaviors and could withstand 70 J impact energy with an energy absorption rate around 90 %. This work may provide new strategies and inspiration for the preparation of high-performance flexible mesh materials and further helps in developing applications of spiderweb-inspired mesh fabrics in engineering fields.

From nutrients to fish: Impacts of mesoscale processes in a global CESM-FEISTY eddying ocean model framework

The ocean sustains ecosystems that are essential for human livelihood and habitability of the planet. The ocean holds an enormous amount of carbon, and serves as a critical source of nutrition for human societies worldwide. Climate variability and change impact marine biogeochemistry and ecosystems. Thus, having state-of-the-art simulations of the ocean, which include marine biogeochemistry and ecosystems, is critical for understanding the role of climate variability and change on the ocean biosphere. Here we present a novel global eddy-resolving (0.1° horizontal resolution) simulation of the ocean and sea ice, including ocean biogeochemistry, performed with the Community Earth System Model (CESM). The simulation is forced by the atmospheric dataset based on the Japanese Reanalysis (JRA-55) product over the 1958–2021 period. We present a novel configuration of the CESM marine ecosystem model in this simulation which includes two zooplankton classes: microzooplankton and mesozooplankton. This novel planktonic food web structure facilitates “offline” coupling with the Fisheries Size and Functional Type (FEISTY) model. FEISTY is a size- and trait-based model of fish functional types contributing to fisheries. We present an evaluation of the ocean biogeochemistry, marine ecosystem (including fish types), and sea ice in this high resolution simulation compared to available observations and a corresponding low resolution (nominal 1°) simulation. Our analysis offers insights into environmental controls on trophodynamics within the ocean. We find that this high resolution simulation provides a realistic reconstruction of nutrients, oxygen, sea ice, plankton and fish distributions over the global ocean. On global and large regional scales the high resolution simulation is comparable to the standard 1° simulation, but on smaller scales, explicitly resolving the mesoscale dynamics is shown to be important for accurately capturing trophodynamic structuring, especially in coastal ecosystems. We show that fine-scale ocean features leave imprints on ocean ecosystems, from plankton to fish, from the tropics to polar regions. This simulation also offers insights on ocean acidification over the past 64 years, as well as how large-scale climate variations may impact upper trophic levels. The data generated by the simulations are publicly available and will be a fruitful community resource for a large variety of oceanographic science questions.

Thermal response of freshwater ciliates: Can they survive at elevated lake temperatures?

Abstract Ciliates are a well‐defined, species‐rich, versatile group of heterotrophic and mixotrophic protists. Their response to increased temperature during global warming is critical for the structure and functioning of freshwater food webs. I conducted a meta‐analysis of the literature from field studies and experimental evidence to assess the parameters characterising the thermal response of freshwater ciliates. The shape of the thermal performance curve predicts the ciliates' survival at supraoptimal temperatures (i.e., the width of the thermal safety margin). The ciliates' typical thermal safety margin is c. 5°C. More than two‐thirds of the freshwater ciliates dwelling permanently or occasionally in the pelagial cannot survive at temperatures exceeding 30°C. Likewise, cold‐stenothermic species, which represent a significant fraction of euplanktonic ciliates, cannot survive by evolutionary adaptation to rapidly warming environments. The statistical analysis revealed that the ciliates' thermal performance is affected by their planktonic lifestyle (euplanktonic vs. tychoplanktonic), ability to form cysts and nutritional ecology. Bactivorous ciliates have the widest temperature niche, and algivorous ciliates have the narrowest temperature niche. Phenotypic plasticity and genetic variation, favouring the selection of pre‐adapted species in a new environment, are widespread among freshwater ciliates. However, the lack of evidence for the temperature optima and imprecisely defined tolerance limits of most species hampers the present analysis. The extent of acclimation and adaptation requires further research with more ciliate species than the few chosen thus far. Recent eco‐evolutionary experimental work and modelling approaches have demonstrated that the ciliates' thermal responses follow general trends predicted by the metabolic theory of ecology and mechanistic functions inherent in enzyme kinetics. The present analysis identified current knowledge gaps and avenues for future research that may serve as a model study for other biota. Thermal adaptation may conflict with adaptation to other stressors (predators, food availability, pH), making general predictions on the future role of freshwater ciliates in a warmer environment difficult, if not impossible, at present.

Relative equilibria of mechanical systems with rotational symmetry

We consider the task of classifying relative equilibria for mechanical systems with rotational symmetry. We divide relative equilibria into two natural groups: a generic class which we call normal, and a non-generic abnormal class. The eigenvalues of the locked inertia tensor descend to shape-space and endow it with the geometric structure of a three-web with the property that any normal relative equilibrium occurs as a critical point of the potential restricted to a leaf from the web. To demonstrate the utility of this web structure we show how the spherical three-body problem gives rise to a web of Cayley cubics on the three-sphere, and use this to fully classify the relative equilibria for the case of equal masses.

Topological traits are associated with the prevalence of IGP modules in empirical food webs

Exploring how food webs are assembled from basic modules is charming and crucial for understanding how communities are self-organized. As one of the basic modules, intraguild predation (IGP) consists of a prey being consumed by both an intermediate and a top predator, with the former also being consumed by the latter (thus encompassing both predation and competition). This interaction has been shown to govern food web stability, and therefore underpin the organization of network structures. While some studies have been made in understanding the factors and mechanisms behind the prevalence of IGP modules in food webs, the specific role of food web topological structures in relation to these modules remains largely unexplored and is not well understood. Here, 103 food webs were analyzed, and we found that the number of modules in each food web was largely determined by taxon richness and connectance. After controlling richness and connectance, the specific scale-free pattern and core-periphery structure of empirical food webs explains the higher prevalence of IGP modules in empirical food webs better than by chance. Lastly, the loss of taxa which supported large number of IGP modules would lead to serious damage to food web robustness, indicating the keystone role of these taxa in maintaining food web structure and stability. Our results provide new insight into the assembly of empirical food webs from the perspective of IGP modules.

Nearest neighbour analysis as a new probe for fuzzy dark matter

ABSTRACT Fuzzy dark matter (FDM) is a promising candidate for dark matter (DM), characterized by its ultra-light mass, which gives rise to wave effects at astrophysical scales. These effects offer potential solutions to the small-scale issues encountered within the standard cold dark matter (CDM) paradigm. In this paper, we investigate the large-scale structure of the cosmic web using FDM simulations, comparing them to CDM-only simulations and a simulation incorporating baryonic effects. Our study employs the nearest neighbour (NN) analysis as a new statistical tool for examining the structure and statistics of the cosmic web in an FDM universe. This analysis could capture the information absent in the two-point correlation functions. In particular, we analyse data related to the spherical contact, nearest neighbour distances (NND), and the angle between the first and second nearest neighbours of haloes (NNA). Specifically, we utilize probability distribution functions, statistical moments, and fitting parameters, as well as G(x), F(x), and J(x) functions to analyse the above data. Remarkably, the results from the FDM simulations differ significantly from the others across these analyses, while no noticeable distinction is observed between the baryonic and CDM-only simulations. Moreover, the lower FDM mass leads to more significant deviations from the CDM simulations. These compelling results highlight the efficiency of the NN analysis – mainly through the use of the J(x) function, $s_3$, $l_{3}$, and $a_4$ parameters – as a prominent new tool for investigating FDM on large scales and making observational predictions.

Food web collapse and regime shift following goldfish introduction in permanent ponds.

In a global context of invasive alien species (IAS), native predators are often eradicated by functionally different IAS, which may induce complex cascading consequences on ecosystem functioning because of the key role predators play in structuring communities and stabilizing food webs. In permanent ponds, the most abundant freshwater systems on Earth, global human-mediated introductions of alien omnivores such as the pet trade goldfish are driving broad-scale patterns of native predators' exclusion, but cascading consequences on food web structure and functioning are critically understudied. We compared food webs of naturally fishless ponds versus ponds where dominant native predators (newts) had been extirpated by invasive goldfish within the last decade. Integrating community-wide isotopic, taxonomic and functional traits approaches, our study reveals that pond food webs collapsed in both vertical and horizontal dimensions following goldfish introduction and the associated exclusion of native predators. Consumer taxonomic diversity was drastically reduced, essentially deprived of amphibians as well as predatory and mobile macroinvertebrates to the profit of burrowing, lower trophic level consumers (detritivores). Changes in community structure and function underlined a regime shift from a macrophyte-dominated system mainly characterized by benthic primary production (periphyton), to a macrophyte-depleted state of ponds hosting communities mainly associated with phytoplankton primary production and detritus accumulation, with higher tolerance to eutrophication and low dissolved oxygen concentration. Results underline major impacts of widely introduced omnivores such as the goldfish on the functioning of pond ecosystems with potentially dramatic consequences on the key ecosystem services they deliver, such as global biodiversity support or water quality improvement. They also shed light on the key role of submerged aquatic vegetation in supporting diverse communities and complex food webs in shallow lentic systems and call for urgent consideration of threats posed by IAS on ponds' ecosystems by managers and policymakers.

Warming enhanced the interaction effects of fungi and fungivores and soil potassium mineralization in tropical forest

Potassium (K) cycling in forest systems has received less attention than nitrogen (N) and phosphorus (P) cycles, despite its critical role in maintaining primary production and regulating water economy and use under climate warming. This study conducted a 10-year study in which we translocated dominant tropical forest tree seedlings and underlying soil (i.e., in situ soil) from high-altitude sites (600 m a.s.l.) to lower altitude sites at 300 m a.s.l. (+1.0 °C) and 30 m a.s.l. (+2.1 °C) to simulate climate warming in southern China. We investigated soil microbial and nematode communities, soil and foliar K concentrations at the aggregate level, and tree growth under different altitude sites. Microbial community was characterized by high-throughput sequencing, nematodes were identified to the genus level using microscope. The findings revealed that warming treatments significantly (p < 0.01) increased soil fungal gene abundance (+78 % at 300 m and +62 % at 30 m), fungal/bacterial abundance ratio (+121 % at 300 m and +101 % at 30 m), and soil fungivore abundance (+274 % at 300 m and +233 % at 30 m). These results indicate a shift in the soil decomposition pathway from bacterial to fungal-based channels. In addition, warming amplifies the interactions between fungi and fungivores. Aggregates had few effects on microbial biomass, but had significant effect on nematode abundance. Soil microcosm experiments consistently demonstrated that addition of the dominant fungivore Aphelenchoides significantly (p < 0.05) enhanced soil-exchangeable K by stimulating fungal gene abundance and activity. Furthermore, warming-induced changes in forest communities were observed. At the species-specific tree level, Syzygium rehderianum demonstrated the ability to take advantage of this scenario, exhibiting increased K uptake (−4% at 300 m and +32 % at 30 m). This may be attributed to the species being ectomycorrhizal-forming, where colonizing root surfaces can mobilize interlayer and structural K from the minerals. In contrast, Machilus breviflora exhibited lower foliar K concentrations (−42 % at 300 m and −41 % at 30 m) and reduced growth. However, warming had little effect on Schima superba, Myrsine seguinii, Itea chinensis, and Ardisia lindleyana growth. Warming-induced changes in the plant–soil system K cycle highlight the emergence of a new ecosystem structure with different soil web structures and distinct plant community species composition. Our results prompt further research to understand the microbiome-mediated complexities of understudied nutrient cycles, which are likely to be further altered in the future owing to climate change.