Spatial Community Structure Research Articles

Detecting Fish Diversity in Urban‐Impacted Ecosystems: A Comparative Approach of eDNA Metabarcoding and UVC

ABSTRACTComprehensive assessments of coastal biodiversity in complex coral communities are crucial but challenging, particularly under unfavorable conditions such as poor underwater visibility in urbanized and eutrophic environments. Here we aim to examine the scope of underwater diversity detection and community shifts across habitat transitions spanning different geographic regions in Hong Kong SAR, a highly urbanized coastal city with limited underwater visibility of 3.93 ± 1.25 m during the sampling period. We employ and compare two methods: 12S rRNA eDNA metabarcoding coupled with custom built reference database and simultaneous extensive underwater visual census (UVC) surveys. eDNA detected a higher species richness per site. Yet, each survey method featured a distinct species profile with associated trophic guilds, where 98 (32.3%) species found exclusively by UVC and 120 (39.6%) species detected only by eDNA. eDNA featured species from diverse habitats and evolutionary distances, including cryptic and large mobile fishes, offering enhanced prediction on local ecosystem functions. eDNA also recorded 90 putative species that had never been recorded in additional seven yearlong UVC dataset, with seven prospective new occurrence records to the territorial waters. UVC on the other hand was more efficient in documenting reef‐associated species. Both methods captured similar patterns of community spatial structure along the habitat transitions while only eDNA detected more large fish species in offshore compared to sheltered inshore environments, This may suggest inshore overfishing and incapability of UVC in surveying large mobile species in turbid environments. Considering the discrepancies between two methods, we highlight the importance of complementing both UVC and eDNA metabarcoding survey for a complete overview of local biodiversity under unfavored underwater conditions in an urbanized seascape.

Redox potential shapes spatial heterogeneity of mixed-cultured electroactive biofilm treating wastewater

The core of bioelectrochemical systems (BESs) is electrochemically active microorganisms (EAMs), which exert spatial heterogeneity on electrode surface and influences BESs performance. Setting an optimal potential is an effective strategy for improving and optimizing BESs performance, however, how the electrode potential affects spatial structure of microbial community within anode biofilm is not known. Using a complex substrate-fed BES with a wastewater inoculum, this study investigated the community structure and composition of the stratified biofilm developed under the potential of −0.3 V, 0 V, +0.3 V and +0.6 V (vs. saturated calomel electrode) by freezing microtome method and high-throughput sequencing analysis. The spatial heterogeneity of biofilm community was found to be dependent on the electrode potential and a less stratified community structure was observed for +0.6 V than other potentials. Within the biofilms, the inner layers selected more Geobacter and the outer layers enriched more Acinetobacter and Serratia, potentially suggested a stratification of electron transfer pathway and metabolite-based interspecies communications. The results demonstrated the response of spatial heterogeneity of anode biofilm community to the change of electrode potential, which helps to understand the selectivity and enrichment of kinetically efficient anodic microbiome by electron potential.

Swarming bacteria exhibit developmental phase transitions to establish scattered colonies in new regions.

The bacterial Type 9 Secretion System (T9SS) is essential for the development of periodontal diseases and Bacteroidetes gliding motility. T9SS-driven motile bacteria, abundant within the human oral microbiota, transport non-motile oral microbes and bacteriophages as cargo, shaping the spatial structure of polymicrobial communities. However, the physical rules governing the dispersal of T9SS-driven bacterial swarms are barely understood. Here, we collected time-lapse images, under anaerobic conditions, of developing swarms of a T9SS-driven microbe common to the human oral microbiota. Tracking of swarms revealed that small peripheral flares emerging from a colony develop structures that resemble fireworks displaying a chrysanthemum effect and flower-like patterns that convert to wave-like patterns and which further evolve into scattered microcolonies. Particle-image velocimetry showed density-dependent phase transitions and initial vorticity within these emerging patterns. Numerical simulations demonstrate that these patterns arise due to changes in swarm speed and alignment strength. Our data reveal a strategy used by an anaerobic swarming bacterium to control swarm behavior, resulting in scattered microcolonies distant from the mother colony, thus reducing competition for resources among colony members. This might ensure species survival even if conditions change drastically in one location of the human oral cavity.

Pengembangan Kawasan Pariwisata Berbasis Kearifan Lokal Kampung Asey Besar

When viewed from a cultural perspective, the tourism industry indirectly plays an important role in the development of regional culture. Local wisdom is the potential of a culture that can be developed by the community so that the authenticity of that culture is maintained. It is hoped that the development of a tourism area based on local wisdom will have a positive impact on the people of Asey Besar Village. This research aims to determine the potential of a local wisdom-based tourism area in Asey Besar Village. To find out about the development of a tourism area based on local wisdom in Asey Besar Village, Jayapura Regency. The research method used is a qualitative descriptive method. Based on the research results, it was found that the potential for developing a tourism area based on local wisdom in Asey Besar Village is planned as a strategic area for traditional villages with known resources in the form of natural beauty, and has a landscape character with flora and fauna habitat, clear waters, topography, type of vegetation. Planning for regional development as a tourism area with local wisdom is carried out by increasing and developing investment in the social and cultural spatial structure of regional communities in Asey Besar Village. For the Government and Community, efforts must be made to preserve the potential of local wisdom in Asey Besar Village which supports tourism by the government and community as those responsible for protecting and maintaining local wisdom while maintaining culture as a characteristic of the tribal community of Asey Besar Village.

Species diversity and structural features of macrobenthos in coastal lagoon ecosystems, the Kandalaksha Bay, White Sea taken as an example

The Kandalaksha Bay of the White Sea taken as an example, the present study is devoted to its coastal lagoon ecosystems known to differ in their species diversity and structural features, including macrobenthos. Features of the species composition, spatial structure and diversity of macrobenthic sublittoral communities in 4 coastal lagoon ecosystems of the White Sea were studied and analyzed. In the sublittoral of the study lagoons, 39 species of zoobenthos and 4 species of sea weeds and algae (Zostera marina, Cladophora sericea, Ruppia maritima, Salicornia pojarkovae) were found. The lowest indices of species diversity and biomass of macrobenthos were revealed in lagoons significantly fenced off and remote from the sea, where littoral eurytopic small species of zoobenthos (Macoma balthica, Peringia ulvae, Tubificoides benedii, Littorina littorea, Mytilus edulis, Chironomus salinarius) were found to mainly dominate. In the lagoons in which the connection to the sea was stronger, less euryhaline sublittoral invertebrate species prevailed with higher indices of species diversity and total biomass of the macrobenthos community (Nereimyra punctata, Terebellides stroemi, Caprella linearis, Asterias rubens, Molgula griffithsii). Most of the lagoon ecosystems we examined, with the exception of the one most open to the sea, were characterized by low values of ABC indices and a disturbed structure of the macrobenthos community with the predominance of mainly small species of detritophages, this being associated with the negative effects of siltation, carbon loading and salinity (especially in spring or during the times of heavy rain).

Spatial structure and potential processes linking fish and benthic communities in a protected reef ecosystem in SE Brazil

Top-down and bottom-up processes can mediate the structuring of biological communities. Several studies have provided separate support for those processes in pelagic and benthic compartments of reef systems but studies focusing on whole-reef processes are less common. Here, we sampled 3 ‘reef compartments’ in the Alcatrazes Archipelago in Southeastern Brazil: benthic cover of colonial organisms, solitary organisms, and reef fish (i.e. pelagic) to identify the groups responsible for spatial community structure among reefs. A dynamic mosaic structure best defines the assemblages of each compartment, with substantial changes observed among sites over 2 consecutive years and at 2 depth strata, separated by a sharp thermocline. Changes in benthic cover of colonial organisms are largely due to the extent of the blooming of Sargassum canopies, algal turfs, and the zoanthid Palythoa caribaeorum. Solitary organisms show a consistent monotonic change in the abundance of sea urchins, ascidians, and snails. Fish assemblage structure differed among reefs; however, we observed that large invertivore fish tended to concentrate in warmer water above the thermocline and small fish of different feeding habits were found in deeper and colder water in all reefs. We observed a potential strong link between the reefscape and solitary organisms, with a negative relationship between the abundance of urchins and the cover of Sargassum spp. suggesting top-down control. A second link is indicated by a positive relationship between low-lying cover composed of articulated turf and P. caribaeorum and larger invertivorous fish, suggesting bottom-up control through the provision of favorable foraging grounds.

Ecological setting of phlebotomine sand flies in the Republic of Kosovo

Sand flies (Diptera, Psychodidae) are the principal vectors of Leishmania spp., the causative agents of leishmaniasis, as well as phleboviruses. In the Balkans, the endemicity and spreading of sand fly-borne diseases are evident, particularly in the Republic of Kosovo, a country with a predominantly humid continental climate. To date, understanding the drivers behind the spatial structure and diversity patterns of sand fly communities in humid continental regions remains limited. Therefore, elucidating the geographical and ecological factors contributing to the presence of potential vector species in the country is crucial. We aimed to enhance our understanding of factors influencing sand fly occurrence in cool and wet wintering humid continental areas, which could serve as a model for other countries with similar climatic conditions. Therefore, we assessed the currently known sand fly fauna through detailed environmental analyses, including Voronoi tessellation patterns, entropy calculations, Principal Coordinate and Component Analyses, Hierarchical Clustering, Random Trees, and climatic suitability patterns.Notable differences in the ecological tolerance of the species were detected, and the most important climatic features limiting sand fly presence were wind speed and temperature seasonality. Sand flies were observed to prefer topographical environments with little roughness, and the modelled climatic suitability values indicated that, dominantly, the western plain regions of Kosovo harbour the most diverse sand fly fauna; and are the most threatened by sand fly-borne diseases. Phlebotomus neglectus and P. perfiliewi, both confirmed vectors for L. infantum and phleboviruses, were identified as two main species with vast distribution in Kosovo. Contrary to this, most other present species are relatively sparse and restricted to temperate rather than humid continental regions.Our findings reveal a diverse potential sand fly fauna in Kosovo, indicating the need for tailored strategies to address varying risks across the country's western and eastern regions in relation to leishmaniasis control amidst changing environmental conditions.

Does the universal adaptive strategy theory apply to natural regeneration in heterogeneous subtropical karst forests?

The universal adaptive strategy theory (UAST) describes how the ecological strategy of plants changes along the succession after disturbance. However, whether it applies to those off-peak successional pathways in extremely heterogeneous forests is uncertain. This study established a series of forest dynamic plots along the natural regeneration in subtropical karst forests, and aimed to verify whether UAST applied to the succession in extremely heterogeneous forests. By measuring the dominant plant functional traits (PFTs) and quantifying the plant ecological strategy spectrum, we found that the PFTs varied significantly along the natural regeneration, as did plant ecological strategies. Further results showed that the C- and S-strategy dominated the community-level ecological strategy spectrum. In addition, the C-strategy gradually increased along the natural regeneration, while the S-strategy exhibited a decreasing trend. The community spatial structure and abiotic factors including soil physicochemical properties and topographic factors jointly drove the ecological strategy spectrum of the plant community, with the community spatial structure playing a more important role. This study provided clear evidence to support Grime’s CSR theory and the UAST, which emphasized the abiotic stress conditions supported the S-strategy plants, while the C-strategy would dominate in relative fertile soil conditions.

Species composition, abundance and spatial structure of bat community hibernating in Tanechkina and Staroladozhskaya Caves, Leningrad Region, Russia

Species composition, abundance and spatial structure of bat community hibernating in Tanechkina and Staroladozhskaya Caves, Leningrad Region, Russia

Environmental DNA metabarcoding reveals fish diversity, community assembly and one invasive species prevalence in a National Park of Liaohe in September

The escalating environmental changes are imposing multiple pressures on biodiversity conservation, thereby, more attention has been paid to fish diversity and community assembly patterns. Fish diversity in Liaohe River has deteriorated significantly due to overfishing, environmental pollution and other reasons, in addition, no fish survey related research has been published in Liaohe National Park in recent years. In order to study the diversity of fish species in the area and to investigate the presence of any invasive species. This study used eDNA metabarcoding to explore the distribution and diversity of fish communities in the Liaohe National Park. The study showed that a total of 54 species of fish from six orders, 14 families, and 39 genera were detected, meantime, the invasive species Lepomis cyanellus was found at two sampling sites. The α-diversity results showed that estuarine sites had the highest species diversity. The spatial structure of fish communities in the upstream and downstream reaches were similar as indicated by non-metric multidimensional scaling. In our study, the fish community is influenced by both deterministic and stochastic processes, with the stochastic processes being the main factor. The potential existence of L. cyanellus in Liaohe National Park might be resulted from aquaculture, ornamental pet trade, other economic fish farming, artificial release. The relatively low number of fish species in this study may be attributed to the limited number of sampling events and sampling sites. In addition to these factors, over exploitation of resources, water pollution, and the invasion of alien species have directly impacted the biodiversity of aquatic life. The results of this study lay a foundation for the future biodiversity investigation in National Parks of China, meantime, the use of eDNA monitoring is crucial to prevent, to control and limit the spreading of invasive species in advance.

Minor effect of wind exposure and littoral slope on macrophyte characteristics in non-impacted lowland lakes of Poland.

Aquatic vegetation is a reliable indicator of the ecological condition of surface waters. Abundance, composition and spatial structure of aquatic communities are shaped by an array of factors, which include both natural abiotic features of an ecosystem and external influences. We investigated whether the physical features, i.e., wind exposure and slope of the lake basin, have a significant impact on the taxonomic composition and spatial structure of macrophyte communities from non-impacted, highly alkaline, lowland lakes of the European plains (Poland). We further examined whether these features can affect the classification of the ecological status of lakes assessed in accordance with the Water Framework Directive requirements. Morphological, botanical and physicochemical data from 260 transects in 16 non-disturbed lakes of Polish lowlands surveyed in the years 2011-2016 were analysed. For each transect, littoral slope and wind exposure were calculated. Additionally, the total phosphorus concentration was used as a proxy of water trophy. The relationships between environmental variables and macrophyte indices as well as the syntaxonomic composition of aquatic and rush vegetation (dependent variables) were analysed using multidimensional ordination techniques (redundancy analysis, variation partitioning and indicator values), correlation and regression analysis. Among the three analysed environmental factors (littoral slope, wind exposure and water trophy), in almost all cases the latter explained the highest variance in the macrophyte community, while the contribution of the first two was at most moderate, weak or usually statistically insignificant. However, lakes with steeper slopes were more frequently inhabited by stoneworts and had better ecological status than those with a gentle littoral shape. This may be attributed to the links between lake morphometry and rate of eutrophication, with deep lakes supporting more effective dilution of substances. Furthermore, lower light requirements of charophytes than of higher plants and the capacity to growth in unstable sediments facilitate charophyte establishment in deeper and steeper parts of the littoral over higher plants. Our findings suggest that in lowland lakes with relatively small areas, moderate depths and low wind exposure typical of European plains, slopes and weaving do not hamper vegetation development and do not negatively affect the macrophyte assessment of ecological status. In such ecosystems, eutrophication seems to be a more important factor determining aquatic vegetation than physical features.

Emergent antibiotic persistence in a spatially structured synthetic microbial mutualism.

Antibiotic persistence (heterotolerance) allows a subpopulation of bacteria to survive antibiotic-induced killing and contributes to the evolution of antibiotic resistance. Although bacteria typically live in microbial communities with complex ecological interactions, little is known about how microbial ecology affects antibiotic persistence. Here, we demonstrated within a synthetic two-species microbial mutualism of Escherichia coli and Salmonella enterica that the combination of cross-feeding and community spatial structure can emergently cause high antibiotic persistence in bacteria by increasing the cell-to-cell heterogeneity. Tracking ampicillin-induced death for bacteria on agar surfaces, we found that E. coli forms up to 55 times more antibiotic persisters in the cross-feeding coculture than in monoculture. This high persistence could not be explained solely by the presence of S. enterica, the presence of cross-feeding, average nutrient starvation, or spontaneous resistant mutations. Time-series fluorescent microscopy revealed increased cell-to-cell variation in E. coli lag time in the mutualistic co-culture. Furthermore, we discovered that an E. coli cell can survive antibiotic killing if the nearby S. enterica cells on which it relies die first. In conclusion, we showed that the high antibiotic persistence phenotype can be an emergent phenomenon caused by a combination of cross-feeding and spatial structure. Our work highlights the importance of considering spatially structured interactions during antibiotic treatment and understanding microbial community resilience more broadly.

Features of the structure and spatial distribution of microbial communities of river ecosystems of the Amur Basin (Eastern Transbaikalia)

The spatial distribution and structure of microbial communities of river ecosystems in the Amur basin of Eastern Transbaikalia have been studied. The Argun River and its 7 main tributaries have been studied. It was established that the microbial communities of the upper reaches of the rivers under study are formed under the influence of the temperature factor, and are characterized by the total number of bacteria, which in water averages 1.83 × 106 cells/ml, in soil – 2.21 × 109 cells/ml. In the middle reaches of rivers, a stable rheophilic microbial community is formed, the structure and spatial distribution of which depends on the specific hydrological regime of the river and the landscape of the territory. The total number of bacteria in river water here reaches on average 3.03 × 106 cells/ml, in the soil – 2.52 × 109 cells/ml. In the lower reaches, a microbial community with the characteristics of limnosystems is formed, which has a close relationship with water mineralization and is characterized by an average total number of bacteria in water - 3.12 × 106 cells/ml, in soil - 3.06 × 109 cells/ml. Microbiological assessment of water quality showed that the studied rivers belong to pollution classes I - III, and their waters are characterized as oligosaprobic - transitional from β- to α-mesosaprobic.

Species prefer to shifting niche positions rather than expanding niche breadth to adapt to the heterogeneous karst forests

The interspecific variations of plant functional traits can characterize the niche positions of species within communities, while the intraspecific variations can accurately display the species’ niche breadth. Revealing relative contributions of intra- and interspecific variations to plant functional community structure is crucial in understanding how the species coexist together, especially in species-diverse ecosystems. To explore how the intra- and interspecific variations of plant functional traits change along the successional pathway in heterogeneous conditions, we established a series of plots and measured main plant functional traits along the natural regeneration in karst forest ecosystems. By quantifying the intra- and interspecific variations of plant functional traits, we found that the changes in intraspecific variations were relatively lower compared to changes in interspecific variations throughout the natural regeneration. Further analysis showed that the community spatial structure contributed more to the intraspecific variations of plant functional traits, while the soil physicochemical properties contributed more to interspecific variations. Our study suggested that tree species might tend to narrow their niche and change the positions to release the niche overlap when faced with heterogeneous habitat conditions.

Environmental DNA biomonitoring reveals the human impacts on native and non-native fish communities in subtropical river systems

Subtropical rivers are one of the hotspots of global biodiversity, facing increased risks of fish diversity changes and species extinction. However, until now, human impacts on native and non-native fish communities in subtropical rivers still lack sufficient effort. Here, we used the environmental DNA (eDNA) approach to investigate fish communities in the Dongjiang River of southeast China, a typical subtropical river, and explored the effects of regional land use and local water pollution on fish taxonomic and functional diversity. Our data showed that 90 species or genera of native fish and 15 species or genera of non-native fish were detected by the eDNA approach, and there was over 85% overlap between eDNA datasets and historical records. The taxonomic and functional diversity of all, native and non-native fish communities showed consistent spatial patterns, that is, the upstream of the tributary was significantly higher than that of the mainstream and downstream. Land use and water pollution such as COD and TP were the determinants in shaping the spatial structure of fish communities, and water pollution explained 31.56%, 29.88%, and 27.80% of the structural variation in all, native and non-native fish communities, respectively. The Shannon diversity and functional richness of native fish showed a significant downward trend driven by COD (pShannon = 0.0374; pfunctional = 0.0215) and land use (pShannon = 0.0159; pfunctional = 0.0441), but they did not have significant impacts on non-native fish communities. Overall, this study emphasizes the inconsistent response of native and non-native fish communities to human impacts in subtropical rivers, and managers need to develop strategies tailored to specific fish species to effectively protect water security and rivers.

Microplaston artificial polymers in the Miass River and Lake Turgoyak (Southern Urals, Russia) in the early stages of colonisation

Aim. To identify the composition and features of the spatial structure of microfouling (microplaston) during the early stages of colonisation of the surfaces of artificial polymer films (LDPE) in the natural habitats of the Miass River and Lake Turgoyak (Southern Urals). The early stages of polymer microfouling which create the basis for further complexity of its spatial mosaic are considered, taking into account the surface microlandscape and the possibilities it creates for the location of community components.Materials and Methods. Fragments of polymer films (LDPE) manufactured for household use were collected in the waters of the Miass River and Lake Turgoyak in June 2023. Samples were selected that were exposed in natural reservoirs for at least several months. Analysis of the composition, structure and spatial organization of microplastonic communities was carried out using light and SEM microscopy.Results. The microplaston in the early stages of growth varied significantly among the habitats studied. On LDPE films from the Miass River they were dominated by sessile armored amoebae (Granofilosea: Microgromiidae), attached diatoms (Bacillariophyta: Achnanthaceae, Cocconeidaceae) developed as a mass and encrusting green microalgae (Chlorophyta, Charophyta) were also found. In Lake Turgoyak cortical green microalgae clearly dominated, together with other diatoms (Bacillariophyta: Rhopalodiaceae, Cocconeidaceae). Trichome and coccoid forms of cyanoprokaryotes (Cyanobacteria: Pseudanabaenaceae, Rivulariaceae, Chamaesiphonaceae, Microcystaceae) were also abundant. The colonisation of films by individual species varied among habitats and also depended on the surface microrelief.Conclusion. Analysis of the microplaston of LDPE films in hydrologically different habitats demonstrated the features of early colonisation of these substrates, the biotope‐specificity of the species and spatial structure of communities, as well as the organisation of colonial settlements of a number of species.

Community composition and the environment modulate the population dynamics of type VI secretion in human gut bacteria.

Understanding the relationship between the composition of the human gut microbiota and the ecological forces shaping it is of great importance; however, knowledge of the biogeographical and ecological relationships between physically interacting taxa is limited. Interbacterial antagonism may play an important role in gut community dynamics, yet the conditions under which antagonistic behaviour is favoured or disfavoured by selection in the gut are not well understood. Here, using genomics, we show that a species-specific type VI secretion system (T6SS) repeatedly acquires inactivating mutations in Bacteroides fragilis in the human gut. This result implies a fitness cost to the T6SS, but we could not identify laboratory conditions under which such a cost manifests. Strikingly, experiments in mice illustrate that the T6SS can be favoured or disfavoured in the gut depending on the strains and species in the surrounding community and their susceptibility to T6SS antagonism. We use ecological modelling to explore the conditions that could underlie these results and find that community spatial structure modulates interaction patterns among bacteria, thereby modulating the costs and benefits of T6SS activity. Our findings point towards new integrative models for interrogating the evolutionary dynamics of type VI secretion and other modes of antagonistic interaction in microbiomes.

Features of the spatial distribution, structure and functional activity of microbial communities in river ecosystems of Eastern Transbaikalia (on the example of the Khilok River)

The spatial distribution, structure, and functional activity of microbial communities in one of the river ecosystems of Eastern Transbaikalia, the Khilok River, its tributaries, and floodplain lakes, were studied. It has been established that the microbial communities of the upper reaches of the Khilok River are formed under the influence of the waters of the source of the river of the eutrophic Lake Shakshinskoye and the allochthonous matter supplied with the terrigenous runoff. The total number of bacteria here reaches 2.2 × 106 cells/mL, and bacterial production is 0.46 g / m3 × day-1. In the middle and lower reaches of the river, a stable rheophilic microbial community is formed, the structure and functioning of which depend on the autochthonous and allochthonous substance of the ecosystem, the specifics of the hydrological regime of the river, its tributaries and floodplain lakes. The total number of bacteria here rises to 5.1 × 106 cells/mL, and bacterial production to 0.82-1.87 g / m3 × day-1. In shallow floodplain lakes and in sections of rivers where an additional pool of organic matter enters, the maximum functional indicators of the microbial community of the river ecosystem were recorded. The rate of reproduction of bacteria here reaches 11-42 hours, and bacterial production is 8.32 g/m3 × day-1.

Shrimp community structure and influence of environmental variables in the East China Sea and Yellow Sea in spring.

Based on data collected from research vessel cruises performed in May 2020 off the East China Sea (ECS) and the southern Yellow Sea (YS) (26°30'-35°00' N, 120°30'-127°00' E), we analyzed the shrimp community and its relationships with environmental variables by using index of relative importance, biodiversity indices, and multivariate techniques. A total of 29 species were recorded, belonging to 11 families and 19 genera. The dominant species were Metapenaeopsis longirostris, Leptochela gracilis, Solenocera melantho, Crangon hakodatei, Parapenaeus fissuroides, Plesionika izumiae, and Trachypenaeus curvirostris, which together accounted for 82.9% of the total biomass and 90.8% of the total abundance of shrimps. Results of Cluster and NMDS analyses showed that three groups were identified for the shrimp community in the ECS and YS in spring, including group A (inshore of northern ECS and YS group), group B (offshore of northern ECS group) and group C (southern ECS group). ANOSIM and SIMPER analysis showed significant differences between group A and B, gourp A and C, and group B and C, with the dissimilarity of 92.2%, 95.8% and 91.6%, respectively. The typical species were T. curvirostris, C. hakodatei, L. gracilis and Palaemon gravieri in group A, and S. melantho in group B, and M. longirostris, P. fissuroides, P. izumiae and Solenocera alticarinata in group C. Significant differences were also detected in biomass, diversity index, species richness index and evenness index among groups, with significantly greater values in group C than those in A and B. Environmental variables and the substrate also displayed significant differences among groups. Results of canonical correspondence analysis showed that bottom temperature, bottom salinity, depth, and the substrate were the main environmental variables affecting spatial structure of shrimp community. Water mass characteristics and substrate type had important influences on the distribution of shrimp community in the ECS and YS in spring.

Distribution patterns and driving mechanism of soil protozoan community at the different depths of Larix principis-chinensis forest in the Luya Mountain, China.

To reveal the assembly mechanisms of soil protozoan community in subalpine forest ecosystems, we analyzed the composition and diversity of protozoan communities and their drivers at the six strata (the litter profile, humus profile, 0-10 cm, 10-20 cm, 20-40 cm and 40-80 cm) of soil profiles in subalpine Larix principis-rupprechtii forest in Luya Mountain using Illumina Miseq high-throughput sequencing technology. The results showed that protozoa in the soil profiles belonged to 335 genera, 206 families, 114 orders, 57 classes, 21 phyla, and 8 kingdoms. There were five dominant phyla (relative abundance >1%) and 10 dominant families (relative abundance >5%). The α diversity decreased significantly with increasing soil depth. Results of PCoA analysis showed that the spatial composition and structure of protozoan community differed significantly across soil depths. The results of RDA analysis showed that soil pH and soil water content were important factors driving protozoan community structure across soil profile. Null model analysis suggested that the heterogeneous selection dominated the processes of protozoan community assemblage. Molecular ecological network analysis revealed that the complexity of soil proto-zoan communities decreased continuously with increasing depth. These results elucidate the assembly mechanism of soil microbial community in subalpine forest ecosystem.