Niche Overlap Research Articles

Reclamation of abandoned cropland switches fungal community assembly from deterministic to stochastic processes

Soil microbial communities are major drivers of cycling of soil nutrients that sustain plant growth and productivity. Yet, a holistic understanding of the impact of abandoned agricultural land reclamation on the soil microbe is still poorly understood, especially for the microbial community assembly mechanisms. Here, we investigated the influence of reclamation on the relative importance of stochastic and deterministic processes in shaping microbial community assembly. After reclaiming abandoned cropland for corn and soybean cultivation, the fungal community assembly was shifted to stochastic processes, while bacterial communities remained predominantly influenced by stochastic processes. Our study revealed that reclamation did not significantly affect bacterial diversity, community niche breadth, and community similarity. In contrast, fungal communities exhibited lower alpha diversity, narrower niche breadths, greater niche overlap and higher community similarity in corn and soybean cultivation treatment in response to reclamation. Moreover, soil pH and soil available phosphorus were the most important environmental factors influencing fungal richness, niche breadths, community assembly processes, and community similarity. Together, the reclamation of abandoned cropland promoted the transformation of the fungal community assembly from deterministic process to a stochastic process, leading to decreased fungal diversity and broader ecological niche width, ultimately resulting in greater similarity among fungal communities. This finding provides insight into the varied responses of microbial diversity and ecological process to abandoned cropland reclamation, offering valuable guidance for the conservation and sustainable management of abandoned cropland in future land-use practices.

Restorative function of offshore longline mussel farms with ecological benefits for commercial crustacean species

Offshore ocean aquaculture is expanding globally to meet the growing demand for sustainable food production. At the United Kingdom's largest longline mussel farm, we assessed the potential for the farm to improve the habitat suitability for commercially important crustaceans. Modelled distribution patterns (GAM & GLM) predicted the low complexity seabed beneath the mussel farm was 34–94 % less suitable for European lobster (Homarus gammarus) and brown crab (Cancer pagurus) than nearby rocky reefs. The mussel farm operations, however, contributed large amounts of living mussels and shell material to the seabed. Acoustic telemetry revealed that H.gammarus remained within the farm for between 2 and 283 days using both the farm anchors and areas of seabed dominated by fallen mussels for refuge. In contrast, C. pagurus movements showed no affinity to either the farm infrastructure or benthic habitat under the farm. Stable isotope analysis indicated a high dietary niche overlap in C. pagurus and H. gammarus (67.8 and 84.6 %) between the mussel farm (mixed muddy sediment) and nearby rocky reef. Our mixed-methods suggest that the mussel farm augments structural complexity on the seabed providing refuge and similar feeding opportunities for lobster and crab as their typical habitat on rocky reefs. Longline mussel farms can deliver profound biodiversity-positive effects through biogenic augmentation of degraded habitat for commercial species and potential for co-benefits to local fisheries.

The role of deep hybridization in fern speciation: Examples from the Thelypteridaceae.

Hybridization is recognized as an important mechanism in fern speciation, with many allopolyploids known among congeners, as well as evidence of ancient genome duplications. Several contemporary instances of deep (intergeneric) hybridization have been noted, invariably resulting in sterile progeny. We chose the christelloid lineage of the family Thelypteridaceae, recognized for its high frequency of both intra- and intergeneric hybrids, to investigate recent hybrid speciation between deeply diverged lineages. We also seek to understand the ecological and evolutionary outcomes of resulting lineages across the landscape. By phasing captured reads within a phylogenomic data set of GoFlag 408 nuclear loci using HybPhaser, we investigated candidate hybrids to identify parental lineages. We estimated divergence ages by inferring a dated phylogeny using fossil calibrations with treePL. We investigated ecological niche conservatism between one confirmed intergeneric allotetraploid and its diploid progenitors using the centroid, overlap, unfilling, and expansion (COUE) framework. We provide evidence for at least six instances of intergeneric hybrid speciation within the christelloid clade and estimate up to 45 million years of divergence between progenitors. The niche quantification analysis showed moderate niche overlap between an allopolyploid species and its progenitors, with significant divergence from the niche of one progenitor and conservatism to the other. The examples provided here highlight the overlooked role that allopolyploidization following intergeneric hybridization may play in fern diversification and range and niche expansions. Applying this approach to other fern taxa may reveal a similar pattern of deep hybridization resulting in highly successful novel lineages.

Environmental Filters Structure Cushion Bogs' Floristic Composition along the Southern South American Latitudinal Gradient.

The environmental filtering hypothesis predicts that abiotic factors restrict communities by selecting species capable of survival and persistence under specific conditions, resulting in variations in beta diversity, phylogenetic clustering, and niche differentiation among communities when studying environmental gradients. Cushion bogs and high-altitude wetlands along the Andes display homogeneous flora contrasting with zonal vegetation. Despite being influenced by microclimatic conditions, these ecosystems are subject to diverse environmental effects. Here, we test the environmental filtering hypothesis on the structure of cushion bog communities along a broad-scale latitudinal gradient from 15° S to 42° S. We analyzed 421 bogs and 293 species across three macroclimatic regions with distinct summer, winter, and transitional arid rainfall regimes. Using variance partitioning and membership-based regionalization models, we examined the impacts of climatic, edaphic, and spatial variables on beta diversity. We also assessed species' niche overlap and the influence of environmental filters on the communities' phylogenetic diversity. Results show that species turnover and niche overlap vary with macroclimatic differences, delineating three distinct regions. Notably, phylogenetic clustering in the driest part of the gradient (23° S-24° S) highlights the impact of environmental filtering. Aridity and temperature variations at a broad scale serve as environmental filters shaping the composition of bog communities across southern South America.

Plasticity and overlap of trophic niches in tropical breeding Laridae

Trophic ecology of seabirds in tropical regions remains poorly understood despite the large number of multispecies breeding colonies supported by these ecosystems. Here, we used the isotopic niche (δ15N and δ13C) of 5 Laridae species at 2 breeding areas in Cuba to analyze the plasticity and interspecific overlap of trophic niche determined from chick down and feather samples. The down samples reflected the female trophic regime before laying, while the feather samples incorporated the trophic regime of the chicks provided by the parents during rearing. Two main species groups were identified by their isotopic niche characteristics: species with small and quite stable isotopic niches (trophic specialists) and species with large and highly variable isotopic niches (trophic generalists). Laughing gull Leucophaeus atricilla, royal tern Thalasseus maximus, and sandwich tern T. sandvicensis were the generalists and showed significant isotopic niche differences between breeding areas and phases. Bridled tern Onychoprion anaethetus and roseate tern Sterna dougallii were trophic specialists, but only the former exhibited significant variations in isotopic niche breadth between breeding phases. Overall, trophic (inferred from isotopic) niche overlap was relatively low, suggesting that these tropical seabirds reduce competition through niche partitioning. We concluded that trophic niche plasticity and segregation appear to constitute an important adaptive strategy to ensure the breeding success of sympatrically breeding Laridae in north-central Cuba.

Host tree availability shapes potential distribution of a target epiphytic moss species more than direct climate effects

Climate change significantly impacts the distribution of woody plants, indirectly influencing the dynamics of entire ecosystems. Understanding species' varied responses to the environment and their reliance on biotic interactions is crucial for predicting the global changes' impact on woodland biodiversity. Our study focusses on Dicranum viride, a moss of conservation priority, and its dependence on specific phorophytes (host trees). Using species distribution modelling (SDM) techniques, we initially modelled its distribution using climate-only variables. As a novel approach, we also modelled the distribution of the main phorophyte species and incorporated them into D. viride SDM alongside climate data. Finally, we analysed the overlap of climatic and geographic niches between the epiphyte and the phorophytes. Inclusion of biotic interactions significantly improved model performance, with phorophyte availability emerging as the primary predictor. This underscores the significance of epiphyte-phorophyte interactions, supported by substantial niche overlap. Predictions indicate a potential decline in the suitability of most of the current areas for D. viride, with noticeable shifts towards the northern regions of Europe. Our study underscores the importance of incorporating biotic interactions into SDMs, especially for dependent organisms. Understanding such connections is essential to implement successful conservation strategies and adapt forest management practices to environmental changes.

Suitable Habitat Distribution and Niche Overlap of the Sable (Martes zibellina) and Yellow-Throated Marten (Martes flavigula) in Taipinggou National Nature Reserve, Heilongjiang Province, China.

The global focus on fostering harmonious interactions and promoting rational coexistence among wildlife species to uphold or reinstate biodiversity remains a prominent area of interest. We conducted a study on the sable and yellow-throated marten in Taipinggou National Nature Reserve, Heilongjiang, China, using the line transect method and infrared camera traps from 2022 to 2023. We then analyzed the overlap of their suitable habitats and niches with the aim of gaining insight into the interspecific competition between these two species. We found that the suitable habitat areas for the sable and yellow-throated marten were 55.20 km2 and 23.28 km2, accounting for 24.86% and 10.48% of the total area of this study, respectively. The overlap between the suitable habitats for the sable and yellow-throated marten was 15.73 km2, accounting for 28.5% and 67.6% of their suitable habitat, supporting our Hypothesis 1. The first principal component (Dim1) of the niche explained 35.4% of the overall variability, which is mainly related to the environmental variables "Distance from Settlements" and "Distance from Roads". Overall, 25.5% of the total variability was explained by the second principal component (Dim2), associated with "Slope" and "Distance from Coniferous and Broadleaved Mixed Forest". The niches occupied by the sable and yellow-throated marten were both off-center of the environmental background space, with the niches of the sable being larger than those of the yellow-throated marten. Schoener's D index was 0.56, indicating a high degree of niche overlap between the sable and yellow-throated marten, supporting our Hypothesis 2. Our study is helpful in terms of formulating conservation and management policies for the sable and yellow-throated marten.

Shallow tillage mitigates plant competition by increasing diversity and altering plant community assembly process.

Understanding how human activities affect biodiversity is needed to inform systemic policies and targets for achieving sustainable development goals. Shallow tillage to remove Artemisia ordosica is commonly conducted in the Mu Us Desert. However, the impacts of shallow tillage on plant community species diversity, phylogenetic structure, and community assembly processes remain poorly understood. This study explores the effects of shallow tillage on species diversity including three a-diversity and two b-diversity indicators, as well as phylogenetic structure [phylogenetic diversity (PD), net relatedness index (NRI), and nearest taxon index (NTI)]. Additionally, this research analyzes the effects of shallow tillage on the community assembly process. The results showed that the a-diversity index, b-diversity index, and PD of the shallow tillage (ST) communities were significantly higher than those of the non-shallow tillage (NT) communities, and the phylogenetic structures of both the ST and NT communities tended to be differentiated, with competitive exclusion being the main mechanism of plant assembly. However, shallow tillage increased the relative importance of the stochastic processes dominated by dispersal limitation, mitigating plant competition in the communities. This conclusion was supported by the Raup-Crick difference index-based analysis. Therefore, for the ecological restoration of the Mu Us Desert, species with adaptability and low niche overlap should be selected to increase the utilization efficiency of the environmental resources. The results of this study provide a foundation for policy development for ecosystem management and restoration in the Mu Us Desert.

Feeding Habits of Scomber japonicus Inferred by Stable Isotope and Fatty Acid Analyses

Scomber japonicus is widely distributed off the coast of Japan and in the northwestern Pacific. It is an important target for fisheries. To reveal the differences in diet shifts and niche changes of S. japonicus, we collected samples in the high seas of the northwest Pacific (38°59′ N–43°00′ N, 150°30′ E–161°48′ E) from June to August 2021. We utilized stable isotope and fatty acid analyses to study the differences in body length and sex of S. japonicus. The results showed no significant differences in stable isotope values and fatty acid composition between male and female individuals (p > 0.05). Differences in δ13C and δ15N values among different body length groups were also not significant (p > 0.05). Both δ13C and δ15N values showed a trend of increasing and then decreasing across different body length groups. The niche width of S. japonicus in different body length groups first increased and then decreased, with niche overlap among the groups exceeding 60%. Principal component analysis (PCA) results showed that the main fatty acids in S. japonicus were C14:0, C16:0, C18:0, C16:1n-7, C18:1n-9, C18:3n-6, C20:5n-3, C20:4n-6 and 22:6n-3. Except for C18:0 and C20:4n-6, the content of the other fatty acids showed significant differences among different body length groups (p < 0.05). The results of the similarity analysis (ANOSIM) indicated that the fatty acid compositions of the 100–130 mm length group were significantly different from those of the 131–160 mm and 161–190 mm length groups (p < 0.05). However, there were no significant differences among the other size groups (p > 0.05). During the growth and development of S. japonicus, the proportion of krill in their diet gradually decreased. Meanwhile, their consumption of zooplankton, diatoms and fish significantly increased. Additionally, S. japonicus also consumed crustaceans, but their intakes of planktonic bacteria and green algae were relatively low. We suggested that there were no significant differences between male and female individuals of S. japonicus. As they grew and developed, the ecological niche and feeding habits of S. japonicus continuously changed.

Initiation of rest-grazing during soil thawing improves interspecific relationships and stability of plant communities on alpine grassland.

Grazing management is essential to maintain the stability of grassland ecosystems. To determine the optimal rest-grazing period of alpine meadow, five rest-grazing periods were set based on soil thawing and plant re-greening in this study. The niche, interspecific relationships, and stability of plant communities at different rest-grazing periods were investigated. Rest-grazing during soil thawing resulted in a small niche width and niche overlap of plants, overall positive interspecific associations, and a high stability of plant communities. Delayed rest-grazing time to plant re-greening resulted in a large niche width and niche overlap of plants, overall negative interspecific associations, and a low stability of plant communities. Rest-grazing in alpine meadows should begin as soon as possible to promote healthy and sustainable utilization of grasslands.

Intraspecific and interspecific resource partitioning between bumblebee workers and males related to nectar quantity and quality.

Bumblebees are important pollinators for many natural and agricultural systems in temperate regions. Interspecific and intraspecific variation in floral resource preferences have been proposed to influence bumblebee community structure. In particular, sexual dimorphism is a major source of intraspecific niche variation. Although interspecific resource partitioning is well studied, few studies have explored the intraspecific dynamics between workers and males. Here, we report a study on a total of 11528 workers and 2220 males of 14 bumblebee species recorded over 5years in the Hengduan Mountains of Southwest China. We first compared the potential for interspecific and intraspecific competition between workers and males using visitation records and resource partitioning indices (overlap index). We then evaluated the influence of nectar traits on flower preference, including nectar volume and the levels of hexose, sucrose and 10 essential amino acids (EAAs). We found that the niche overlap between intraspecific workers and males was higher than that between different species, and temporal overlap alone did not strongly determine diet overlap. Males of most species preferred flowers with high levels of EAAs and hexose, whereas workers of some species preferred flowers with high nectar volume and sucrose levels. This study suggests that there is floral resource partitioning among bumblebee species, and between workers and males, which may play a key role in alleviating interspecific and intraspecific competition. These findings also provide a useful guide for which kinds of plants might be most valuable for bumblebees, especially the understudied males, in this biodiversity hotspot.

Ontogenetic, Sexual, and Monthly Niche Segregation of Sepia esculenta in the Northern East China Sea Revealed by Stable Carbon and Nitrogen Isotopes.

Golden cuttlefish play a significant role in the food web of the East and Yellow Seas and are a valuable fishery resource in Chinese coastal waters. Samples of golden cuttlefish were obtained from the northern East China Sea between September 2021 and March 2022, and stable isotope methods were utilized in this study to examine the variations in the forage ecology of golden cuttlefish. Our findings reveal dynamic shifts in carbon and nitrogen stable isotopes (δ13C and δ15N), highlighting intricate foraging strategies tailored to growth and environmental changes. A notable trend emerges: an initial growth-linked rise in δ13C and δ15N enrichment, followed by seasonal fluctuations mirroring seasonal food availability. The ontogenetic niche evolution displays striking habitat shifts and trophic level escalation in small mantle length stages, transitioning to niche overlap and subtle trophic shifts later on. Sex-specific differences emerge, with females occupying higher trophic levels than males in most samples. This comprehensive study underscores the complexity and adaptability of golden cuttlefish feeding ecology, inviting further inquiry into their intricate relationships within the marine ecosystem.

Shared use of a mass‐flowering crop drives dietary niche overlap between managed honeybees and bumblebees

Abstract Resource competition between wild pollinators and managed honeybees (Apis mellifera) has the potential to detrimentally impact insect biodiversity as well as wild plant and crop pollination. As honeybees are central place foragers, their competitive impact on wild bees is expected to be structured by hive proximity, in conjunction with foraging decisions related to landscape‐level resource availability. Yet, how these factors structure dietary niche overlap between wild bees and managed honeybees remains unclear. We conducted a field experiment in seminatural grasslands, where honeybee foraging densities and niche overlap with buff‐tailed bumblebees (Bombus terrestris) were measured at four distances (<100, 500, 1000 and 2000 m) from experimentally placed apiaries, during and after the blooming period of mass‐flowering oilseed rape (Brassica napus). We measured honeybee foraging densities using standardized transect surveys, and quantified species diet composition and dietary niche overlap from pollen samples collected from both bee species. Honeybee foraging densities were highest near apiaries and declined sharply beyond 500 m from the apiaries. However, niche overlap was unrelated to hive proximity but positively related to the availability of oilseed rape. Furthermore, there were significant inter‐ and intraspecific differences in pollen diet composition and breadth throughout the season. Synthesis and applications: Niche overlap between honeybees and bumblebees in agricultural environments was due to resource sharing of mass‐flowering oilseed rape. When both honeybees and bumblebees predominantly forage on wild plants, they maintain distinct pollen diets, suggesting there is a low risk of resource competition between these generalist taxa. Conservation actions that promote floral resource availability and diversity in agricultural landscapes are crucial to maintain niche differentiation between managed honeybees and wild bees.

Anti-seasonal flooding drives substantial alterations in riparian plant diversity and niche characteristics in a unique hydro-fluctuation zone.

Human-induced disturbances such as dam construction and regulation have led to widespread alterations in hydrological processes and thus substantially influence plant characteristics in the hydro-fluctuation zones (HFZs). To reveal utilization of limited resources and mechanisms of inter-specific competition and species co-existence of plant communities based on niche breadth and overlap under the different HFZs of the Three Gorges Reservoir (TGR) in China, we conducted a field investigation with 368 quadrats on the effects of hydrological alterations on plant diversity and niche characteristics. The results showed anti-seasonal flooding precipitated the gradual disappearance of the original diverse niches, resulting in the reduction of plant species richness and functional diversity and more obvious competition among plant species with similar resource requirements. Annuals, perennials and shrubs accounted for 71.23%, 27.39% and 1.37%, respectively, suggesting that annuals and flood-tolerant riparian herbs were favored under such novel flooding conditions. A consistent increase in species number, Shannon-Wiener diversity index and Simpson dominance index with altitude was inconsistent with hump-shaped diversity-disturbance relationship of the intermediate disturbance hypothesis, while the opposite trend was observed for the Pielou evenness index. This species distribution pattern might be caused by several synergetic attributes (e.g., the submergence depth, plant tolerant capacity to flooding, life form, dispersal mode and inter-specific competition). Vegetation types shifted from xerophytes to mesophytes and eventually to hygrophytes with the increasing flooding time in the HFZs. Hydrological alterations proved to be the paramount driver of vegetation distribution in the different HFZs. The niche analysis provided the first insights on the mechanisms of resource utilization and inter-specific competition, of which annuals could germinate quickly after soil drainage to achieve the greatest competitive advantages and occupy a larger niche space than other plants. Vegetation was still in the early stage of primary succession in the novel riparian forests. Therefore, vegetation restoration strategies should be biased towards herbaceous plants, due to annuals with better environmental adaptability, supplemented by shrubs and small trees. To establish a complete reference system for vegetation restoration, natural vegetation monitory plots in the different succession stages should be established in the different HFZs of the TGR, and their environmental conditions, community structures and inter-specific relationships further analyzed.

Food chain without giants: modelling the trophic impact of bowhead whaling on little auk populations in the Atlantic Arctic.

In the Atlantic Arctic, bowhead whales (Balaena mysticetus) were nearly exterminated by European whalers between the seventeenth and nineteenth centuries. The collapse of the East Greenland-Svalbard-Barents Sea population, from an estimated 50 000 to a few hundred individuals, drastically reduced predation on mesozooplankton. Here, we tested the hypothesis that this event strongly favoured the demography of the little auk (Alle alle), a zooplanktivorous feeder competitor of bowhead whales and the most abundant seabird in the Arctic. To estimate the effect of bowhead whaling on little auk abundance, we modelled the trophic niche overlap between the two species using deterministic simulations of mesozooplankton spatial distribution. We estimated that bowhead whaling could have led to a 70% increase in northeast Atlantic Arctic little auk populations, from 2.8 to 4.8 million breeding pairs. While corresponding to a major population increase, this is far less than predicted by previous studies. Our study illustrates how a trophic shift can result from the near extirpation of a marine megafauna species, and the methodological framework we developed opens up new opportunities for marine trophic modelling.

Water utilization characteristics of dominant plant species from different functional groups of desert steppe.

Understanding water use characteristics of plants and their interrelations is essential for achieving sustainable vegetation restoration of desert steppe. This study focused on five dominant plant species inhabiting two habitats: sierozem (Populus euphratica, Caragana liouana, and Stipa breviflora) and aeolian sandy soil (P. euphratica, Salix psammophila, and Leymus secalinus). We analyzed δ2H and δ18O isotopes in xylem, soil water, groundwater, and precipitation. By integrating soil water content and root data at various depths, we employed the MixSIAR model to quantitatively assess water utilization characteristics. Results revealed that these plants primarily relied on soil water during the growing season, with variations in water uptake depths at different growth stages. In the sierozem habitat, Populus exhibited significant variations in water source throughout the growing season. Early in the growing season (May to June), P. euphratica primarily extracted soil water from depths of 60-100 cm. During the peak growth period (July to August), water source shifted to depths of 100-200 cm, and returned to the depth of 0-20 cm by the end of the season (September). C. liouana initially utilized soil water at 60-100 cm but shifted to 0-20 cm during and after peak growth. S. breviflora predominantly tapped into soil water at 20-60 cm early and late in the growing season, but shifted to 0-20 cm during peak growth. In the aeolian sandy soil habitat, P. euphratica initially utilized soil water at 60-100 cm but shifted to 0-20 cm during and after peak growth. S. psammophila primarily utilized soil water at 60-100 cm early and during peak growth, shifting to 100-200 cm by the end of the season. L. secalinus mainly relied on soil water at 20-60 cm throughout the growing season. Soil moisture, seasonal precipitation variation, and root distribution influenced vegetation water use patterns. Throughout the growing season, trees, shrubs, and herbs in the sierozem habitat exhibited hydrological niche partitioning, which facilitated their water distribution and utilization. Conversely, dominant plants in the aeolian sandy soil habitat showed hydrological niche overlap, which intensified water competition, particularly between trees and shrubs. Therefore, species traits and soil properties should be given full consideration when selecting species combinations for vegetation restoration. Introducing species combinations with complementary water use characteristics is essential for fostering species diversity and sustainable vegetation restoration in desert steppe.

Fragile futures: Evaluating habitat and climate change response of hog badgers (Mustelidae: Arctonyx) in the conservation landscape of mainland Asia.

The small mammalian fauna plays pivotal roles in ecosystem dynamics and as crucial biodiversity indicators. However, recent research has raised concerns about the decline of mammalian species due to climate change. Consequently, significant attention is directed toward studying various big flagship mammalian species for conservation. However, small mammals such as the hog badgers (Mustelidae: Arctonyx) remain understudied regarding the impacts of climate change in Asia. The present study offers a comprehensive analysis of climate change effects on two mainland hog badger species, utilizing ensemble species distribution modeling. Findings reveal concerning outcomes, as only 52% of the IUCN extent is deemed suitable for the Great Hog Badger (Arctonyx collaris) and a mere 17% is ideal for the Northern Hog Badger (Arctonyx albogularis). Notably, projections suggest a potential reduction of over 26% in suitable areas for both species under future climate scenarios, with the most severe decline anticipated in the high-emission scenario of SSP585. These declines translate into evident habitat fragmentation, particularly impacting A. collaris, whose patches shrink substantially, contrasting with the relatively stable patches of A. albogularis. However, despite their differences, niche overlap analysis reveals an intriguing increase in overlap between the two species, indicating potential ecological shifts. The study underscores the importance of integrating climate change and habitat fragmentation considerations into conservation strategies, urging a reassessment of the IUCN status of A. albogularis. The insights gained from this research are crucial for improving protection measures by ensuring adequate legal safeguards and maintaining ecological corridors between viable habitat patches, which are essential for the conservation of hog badgers across mainland Asia. Furthermore, emphasizing the urgency of proactive efforts, particularly in countries with suitable habitats can help safeguard these small mammalian species and their ecosystems from the detrimental impacts of climate change.

Comparison of the coexistence pattern of mangrove macrobenthos between natural and artificial reforestation.

The abandoned pond-to-mangrove restoration project provides greater advantages than tidal flats afforestation in restoring mangrove ecosystem services and will be the primary method for mangrove restoration in the future. The existing methods for abandoned pond-to-mangrove restoration include artificial restoration through 'dike-breaking, filling with imported soil and tree planting' and natural restoration through 'dike-breaking and natural succession'. However, little is known about which restoration strategy (natural or artificial restoration) provides more benefits to the biodiversity of mangrove macrobethos. Given a prevailing view suggested that artificial restoration should be the preferred approach for accelerating recovery of biodiversity and vegetation structure in tropical regions, we hypothesised higher macrobenthic biodiversity and more complex community structure in artificial restoration than in natural restoration. To test this hypothesis, macrobenthic biodiversity and ecological processes were monitored in a typical abandoned pond-to-mangrove area of Dongzhaigang Bay, China, where artificial and natural restoration methods were used concurrently. Differences in macrobenthic biodiversity, community structure and ecological processes were compared using diversity indices, complex network analysis and null models. Similar species composition and ecological niche overlap and width among macrobenthos were observed at artificial and natural restoration sites. The biotic heterogeneity and interaction among macrobenthos were higher at the natural restoration sites than at the artificial restoration sites. Macrobenthos community assembly at natural and artificial restoration sites was both determined by deterministic processes, with environmental filtering dominating, which explained 52% and 54% of the variations in macrobenthic community structures respectively. Although our findings did not validate the research hypothesis, higher biotic heterogeneity and species interaction among macrobenthos could support natural restoration as the primary method for abandoned pond-to-mangrove projects, because it is a nature-based solution for mangrove restoration.

Rose or Red, but Still under Threat: Comparing Microplastics Ingestion between Two Sympatric Marine Crustacean Species (Aristaeomorpha foliacea and Parapenaeus longirostris).

Increasing plastic contamination poses a serious threat to marine organisms. Microplastics (MPs) ingestion can represent a risk for the organism itself and for the ultimate consumer. Through the analysis of the gastrointestinal tract, coupled with stable isotope analysis on the muscle tissue, this study provides insights into the relationship between MPs pollution and ecology in two commercial marine species caught in the Central Tyrrhenian Sea: Aristaeomorpha foliacea and Parapenaeus longirostris. Stable isotope analysis was conducted to determine the trophic position and the trophic niche width. The gastrointestinal tracts were processed, and the resultant MPs were analysed under FT-IR spectroscopy to estimate the occurrence, abundance, and typology of the ingested MPs. The trophic level of the species was similar (P. longirostris TP = 3 ± 0.10 and A. foliacea TP = 3.1 ± 0.08), with an important trophic niche overlap, where 38% and 52% of P. longirostris and A. foliacea has ingested MPs, respectively. Though species-level differences may not be evident regarding MP's abundance per individual, a high degree of dissimilarity was noted in the typologies of ingested particles. This research provides valuable insights into how MPs enter marine trophic webs, stressing that isotopic niche analysis should be combined with other methods to explain in detail the differences in MPs ingestion.

An integrated assessment of niche partitioning reveals mechanisms of coexistence between mesocarnivores

Species diversity depends on the capacity of species to coexist, and when these share similar ecological requirements some degree of partitioning of the ecological niche is expected. Within the order Carnivora, direct and indirect interspecific interactions shape community structure and composition. Although strong negative interactions (e.g., interspecific killing) are expected between large carnivores and subordinate species, mesocarnivores that dominate most human disturbed landscapes can still strongly compete for resources given their similar body size and energy requirements. To identify the mechanisms of coexistence between mesocarnivore species in a Mediterranean landscape we assessed the ecological niche overlap between five species (Vulpes vulpes, Meles meles, Martes foina, Herpestes ichneumon, Genetta genetta), by simultaneously measuring the space, time, and trophic resource use. The multi-species occupancy model fit to camera-trapping data revealed spatial co-occurrence between most species’ pairs and an avoidance pattern between only stone marten and Eurasian badger (78 % probability of a negative effect). Using genetically identified scats, we assessed trophic niche breadth and overlap. Niche breadth was narrow for red fox, Eurasian badger, and stone marten, given these species consumed almost exclusively fruits and arthropods, and so trophic niche overlap was high. For the genet and the mongoose, the consumption of different food resources (e.g., mammals, birds, and reptiles) increased niche breadth and decreased the niche overlap with the other sympatric species. Finally, niche segregation was more significant along the temporal axis, since the mongoose has a diurnal activity pattern and the remaining carnivore species, although mostly nocturnal, had small asynchronies in the activity peaks which could decrease the chance of direct encounters. Therefore, our results suggest that similar habitat preferences and ecological requirements rather than interspecific competition shape the mesocarnivores’ resource use in this landscape. Nonetheless, fine-scale temporal segregation seems the main mechanism to facilitate coexistence, together with small differences in trophic resource use, especially for species with high spatial and temporal overlap.