Structure Of Biological Communities Research Articles

Mass mortality events of autochthonous faunas in a Lower Cretaceous Gondwanan Lagerst\xe4tte

Mass mortality events are unusual in the Crato Formation. Although mayflies’ accumulations have been previously reported from that unit, they lacked crucial stratigraphic data. Here we provide the first taphonomic analysis of a mayfly mass mortality event, from a layer 285 cm from the top of the Formation, with 40 larvae, and an overview of the general biological community structure of a three meters deep excavated profile. The only other autochthonous taxon observed in the mayfly mortality layer was the gonorynchiform fish Dastilbe. The larvae and fishes were smaller than usual in the layer 285 cm, suggesting that they lived in a shallow water column. Their excellent preservation and a lack of preferential orientation in the samples suggest an absence of significant transport. All mayflies belong to the Hexagenitidae, whose larvae lived in quiet waters. We also recovered allochthonous taxa in that layer indicative of drier weather conditions. Adjacent layers presented crystals and pseudomorphs of halite, suggesting drought and high salinity. In other layers, Dastilbe juveniles were often found in mass mortality events, associated with a richer biota. Our findings support the hypothesis that the Crato Formation’s palaeolake probably experienced seasonal high evaporation, caused by the hot climate tending to aridity, affecting the few autochthonous fauna that managed to live in this setting.

Earthworm invasion causes declines across soil fauna size classes and biodiversity facets in northern North American forests

Anthropogenic pressures alter the biodiversity, structure and organization of biological communities with severe consequences for ecosystem processes. Species invasion is such a human‐induced ecosystem change with pronounced impacts on recipient ecosystems. Around the globe, earthworms invade habitats and impact abiotic soil conditions and a wide range of above‐ and belowground organisms. In northern North America, where earthworms have been largely absent since the last glaciation period and most earthworm species present today have only been (re‐)introduced a few hundred years ago, invasion impacts have been intensively studied. However, despite several studies assessing impacts of invasive earthworms on soil fauna, studies have rarely investigated the simultaneous responses of different soil‐fauna size groups and biodiversity facets which might respond differently to earthworm invasion and independently affect ecosystem processes. Our study goes beyond previously‐established knowledge on earthworm‐invasion effects by simultaneously assessing differences in four biodiversity facets, namely the abundance, biomass, richness and Shannon index of soil invertebrate macro‐, meso‐ and microfauna communities between high‐ and low‐invasion status plots (n = 80) and in relation to invasion intensity measured as earthworm biomass across four northern North American forests sampled between 2016 and 2017. Across forests and soil‐fauna groups, we found reduced abundance (−33 to −45%) and richness (−18 to −25%) in high compared to low‐invasion status areas. Additionally, meso‐ (−14%) and microfauna biomass (−38%) and macro‐ (−7%) and microfauna Shannon index (−8%) were reduced. Higher invasion intensity (earthworm biomass) was additionally related to reduced soil‐fauna biodiversity. While the studied biodiversity facet was important for the soil fauna response, soil‐fauna size group was comparably unimportant. Given the global ubiquity of earthworm invasion and the importance of soil fauna for key ecosystem processes, our observational results help to assess future impacts of this invasion and the consequences for anthropogenically‐altered ecosystem functioning.

Biological community structure in Krueng Sarah River, Aceh Besar District

This study aims to determine the biological community structure (plankton and macrozoobenthos) in the river from 2017 to 2019. This research method is purposive sampling. The results showed that there were five species of macrozoobenthos, namely Neritrodyas (2017), Polinices hepaticus, Telebra gulata, and Telebralia sulcate (2018), and Tronchus concave (2019). Overall the abundance was high and the same in the three stations. The diversity index (H’) is classified as moderate, while the similarity (E) and dominance (D) are classified as high. Plankton data shows that 15 species of biota were found, namely Rhizoselenia stolterfazhii, Hemialus sp. (2017), Civutum hinnalinclla, Bulduehatae sp., Planctotturnix sp., Canccella sp., Cospidothrea sp., Rhizosolenia sp., and Alana bullata (2018) Isothrix spopsi., Fragila sp., Cylindrusperm raciborska, Cuspidothrix sp., Flagiloria sp., and Cosmarium sp. (2019). Overall, the abundance of plankton is still high. The plankton diversity index is high each year, while the similarity and dominance are low. The water quality data of Krueng Sarah shows that it is still within the tolerance limits for macrozoobenthos and plankton. Therefore, the overall structure of the biological community in Krueng Sarah is still classified as suitable for natural balance.

The California Undercurrent as a Source of Upwelled Waters in a Coastal Filament

AbstractIn the California Current System, cross‐shore transport of upwelled, nutrient‐rich waters from the coastal margin to the open ocean can occur within intermittent, submesoscale‐to‐mesoscale features such as filaments. Time‐varying spatial gradients within filaments affect net cross‐shore fluxes of physical, biological, and chemical tracers but require high‐resolution measurements to accurately estimate. In June 2017, the California Current Ecosystem Long Term Ecological Research program process cruise (P1706) conducted repeat sections by an autonomous Spray glider and a towed SeaSoar to investigate the role of one such coastal upwelling feature, the Morro Bay filament, which was characterized by enhanced cross‐filament gradients (both physical and biological) and an along‐filament jet. Within the jet, speeds were up to 0.78 m/s and the offshore transport was 1.5 Sverdrups (3.8 Sverdrups) in the upper 100 m (500 m). A climatological data product from the sustained California Underwater Glider Network provided necessary information for water mass differentiation. The analysis revealed that the cold, salty side of the filament carried recently upwelled California Undercurrent water and corresponded to higher chlorophyll‐a fluorescence than the warm, fresh side, which carried California Current water. Thus, there was a convergence of heterogeneous water masses within the core of the filament’s offshore‐flowing jet. These water masses have different geographic origins and thermohaline characteristics, which has implications for filament‐related cross‐shore fluxes and submesoscale‐to‐mesoscale biological community structure gradients.

Современное состояние рек бассейна озера Сегозеро (Сегозерское водохранилище, Республика Карелия)

The chemical features and the structure of biological communities in the in the three watercourses of Segozero Lake basin. Analysis for the species composition, abundance and biomass of phytoperiphyton, zooplankton, and zoobenthos was carried out. The effect of natural and anthropogenic factors on the formation of the chemical features and structure of lake hydrobiocenoses was analyzed. Variations in the structure of aquatic organism communities are due primarily to specific hydrographic and hydrological characteristics of river stretches. The paper is discussed the main principles of the changes in a structure and functioning of hydrobiont communities in rivers. The trophic status of the rivers, their saprobiological slate, and the significance of individual communities and biotic indices for bioindication of the ecological state of the rivers, are estimated. We concluded that consideration of three groups of organisms enables more comprehensive and reliable monitoring than assessment based on a single group. The abundance and biomass of phytoplankton, phytoperiphyton, zooplankton, and zoobenthos suggest the relatively high degree of their development in lake water, as well as their activity and stability. A peculiarity of the structure of hydrobiocenoses is that they consist of species with appreciably different sizes: from several microns to several centimeters. Therefore, the lists of species dominating in terms of abundance and biomass differ appreciably.

Biological correlates of sea urchin recruitment in kelp forest and urchin barren habitats

Shifts between the alternate stable states of sea urchin barren grounds and kelp forests correspond to sea urchin density. In the Aleutian Archipelago, green sea urchins Strongylocentrotus polyacanthus are the dominant herbivores that graze kelp forests. Sea urchin recruitment is an important driver that influences sea urchin density, particularly in the absence of top-down control from a keystone predator such as the sea otter Enhydra lutris. To understand how the biological community may influence patterns of sea urchin recruitment, we compared sea urchin recruit (size ≤20 mm) densities with biomass of other benthic organisms in both barren ground and kelp forest habitats at 9 islands across the Aleutian Archipelago. Patterns of biological community structure between the 2 habitats did not explain patterns of sea urchin recruits; however, the same 10 specific taxa were found to correlate with sea urchin recruits in each habitat. Taxa that showed strong positive correlations included Codium, Constantinea, Schizymenia, and hydrozoans, while strong negative correlations were observed with Pachyarthron and Pugettia. Weak positive correlations were observed with Alcyonidium and ascidiaceans in both habitats, while weak variable relationships were detected with Polysiphonia and Corallina between habitats. The observed species-specific relationships may be due to small sea urchin displacement by larger conspecifics, larval responses to settlement cues, post-settlement survival via biogenic refugia, or potentially predation. These potential species-specific interactions were apparent, regardless of habitat, and it can be inferred that they would be preserved in the presence or absence of keystone predation.

Legacy of plant-parasitic nematode communities from past ecosystems and shift by recent afforestation

Ancient ecological legacies and past land use changes may inform on the present structure of biological communities. However, regions providing such successive ecosystems are scarce. In France, the ‘Landes de Gascogne’ area provides such ecological shifts since a few ancient moorland, peatland and oak areas prior the afforestation with maritime pine (Pinus pinaster) 160 years ago still remain. Focusing on soil-borne parasites such as plant-parasitic nematodes (PPN), because forests were recently increasingly impacted by the introduction of intensive agriculture, this study is therefore aimed at comparing the diversity and the community patterns of these organisms at different scales (intra- and intersites) and between different successive ecosystems. The understory vegetation as well as the pedo-climatic characterization of the sampled sites were also considered. Common diversity indices were not impacted by this transition from ancient to past ecosystems. Although the most colonizer nematodes prevailed in all the ecosystems, PPN community structures significantly diverged between both ecosystems. In the logged pine forests, the sediment legacy could have primarily impacted the diversity. Moreover, the PPN diversity would mainly respond to the soil hydromorphicity that determined the associated understory vegetation. Consequently, a significant shift in community structure from moorlands to logged pine to logged pine forests was observed, regarding especially high pathogenic species such as Pratylenchus spp. Thus, analyzing PPN community structure highlights the PPN potential risk to consider during the introduction of intensive cropping systems.

Ecological interaction between cyanobacterial blooms and freshwater fish

Fish are an integral component of aquatic ecosystems and play important roles in maintaining ecosystem stability. However, fish have recently been under great threat due to the deterioration of aquatic environments and the loss of suitable habitats. Due to the intensification of global warming and water eutrophication, the frequency and duration of cyanobacteria blooms have been increasing. Cyanobacteria blooms are often accompanied by cyanotoxin and taste-and-odor substance productions which threaten fish survival and fishery economics. However, the ecological interaction between cyanobacteria and fish is multifaceted. Biomanipulation techniques using fish to regulate excessive cyanobacteria growth have achieved certain effects in the bioremediation of eutrophic water bodies. Therefore, a comprehensive assessment of the impacts of cyanobacteria blooms on freshwater fish populations and the control and driving effects of fish on cyanobacteria are necessary to protect freshwater ecosystems. This study systematically analyzes the effect of cyanobacteria blooms on freshwater fisheries, toxicological effects of harmful cyanobacteria on fish, and the ecological regulation of fish on cyanobacteria. Accordingly, we have proposed future research directions. More attention should be paid to the impacts of cyanobacteria blooms on the physiology, ecology, and behavior of fish, and other animal populations. It is necessary to further clarify whether fish miniaturization and a decline in fish species diversity are directly related to cyanobacteria blooms. Fish exposure to cyanobacteria blooms is a complex topic because aquatic animals are not only exposed to cyanotoxins but also to cyanobacterial cells and lysates which contain various compounds. Thus, the overall effect of complex cyanobacteria biomass or in situ cyanobacteria blooms on fish and the corresponding aquatic ecological risk assessment probably will be the focus of future aquatic research. Moreover, a comprehensive examination of the impact of taste-and-odor substances produced by cyanobacteria on fishery products is also required. Biomanipulation, including traditional and non-traditional techniques, is one of the effective tools to control cyanobacteria blooms. Biomanipulation for water environment restoration can be affected by several factors including geographical characteristics, lake and reservoir morphology, algal composition, stocking mode, and biological community structure. Therefore, the feasibility of implementing biomanipulation should depend on the environmental and biological characteristics of water bodies and specific practices during decision-making processes. Previous studies suggest that combining bivalve and filter-feeding fish may enhance the bioremediation effect of algae but their synergistic effects and effectiveness in natural lakes remain to be further verified. Therefore, this study aims to provide a scientific basis to assess the ecological risk of cyanobacteria blooms, protect freshwater fish, and improve aquatic environments.

Weak Response of Biological Productivity and Community Structure of Phytoplankton to Mesoscale Eddies in the Oligotrophic Philippine Sea

AbstractIn the Philippine Sea, mesoscale eddies have been frequently observed, but little is known about their contributions to the biological productivity and community structure of phytoplankton in the region. In situ carbon and nitrogen uptake rates and phytoplankton community structure were investigated in the Philippine Sea based on the 13C‐15N dual‐tracer technique and photosynthetic pigment analysis from late August to September 2018. Based on the comparison of the phytoplankton community structure among the cold eddy, warm eddy, and outer area, we found that the phytoplankton composition was different in the warm eddy with relatively lower contributions of large phytoplankton. However, a distinct enhancement in phytoplankton biomass over the euphotic zone was not detected even in eddy occurrence. In terms of community, the picoplankton Prochlorococcus was persistently dominant, which was attributed to a low supply and chemical composition of nutrients. The average integrated primary productions (IPP) were 80.4, 75.9, and 76.3 mg C m−2d−1 for the cold eddy, warm eddy, and outer area, respectively. The IPP under the eddy condition was not largely different from that in reference sites, even though the vertical distribution of productivity maximum was found to be different depending on eddy condition. These weak biological responses to mesoscale eddies might be attributed to the sustaining picoplankton‐dominant community structure and no substantial upward inputs of nutrients to the euphotic zone. Our findings represent an important contribution to understanding the biological response of mesoscale eddies in the oligotrophic Philippine Sea.

Spatial distribution of seepages and associated biological communities within Haima cold seep field, South China Sea

More than 30 cold seeps have been discovered on the northern continental slope of the South China Sea (SCS), but only two cold seep sites actively harbor living cold seep communities. One is the Haima cold seep, which is located at a water depth of approximately 1360–1400 m at the northern slope of the SCS. To date, however, the scale of seepage activity, the spatial distribution of seepages, and the biodiversity of benthic fauna associated with this field remain largely unknown because of the absence of a high-resolution seafloor investigation. Here, we report the spatial distribution of individual seepage areas within the Haima cold seep field and their associated biological community structures. Huge gas flares 100 to 200 m inwidth and ascending ~200–800 m into the water column were identified. Seventeen dives conducted by the manned submersible Shenhaiyongshi showed that the Haima consists of at least six individual patch of communities and(or) carbonate mound (HM-1 to HM-6). Outcrops of gas hydrates were observed at HM-3, where active seepage causes dense seep communities to flourish. We found that Mytilidae and Vesicormyidae were predominant, together with Ophiuridae, Chiridotidae, Siboglinidae, Turridae, Actinernidae, Galatheidae, Alvinocarididae, and Lithodidae. Spatially varying patterns of the Haima fauna are attributed to the supply of methane and sulfides, which could provide useful information regarding dynamical seep change and the carbon and sulfur cycles of cold seep areas.

Sedimentary DNA record of eukaryotic algal and cyanobacterial communities in a shallow Lake driven by human activities and climate change

Global freshwater lakes are changing due to human activities and climate change. Unfortunately, sufficient long-term monitoring is lacking for most lakes. However, lake sedimentary archives can extend the instrumental record and reveal historical environmental trends. In particular, sedimentary DNA analysis of lacustrine sediment cores can aid the reconstruction of past trends in eukaryotic algal and cyanobacterial communities, as was conducted in this study for Lake Chaohu in China. The results presented here indicate that the construction of the Chaohu Dam in 1963 is associated with decreased richness of eukaryotic algal and cyanobacterial communities. Several groups, including the eukaryotic algal taxa, Chlorophyceae, and cyanobacterial groups like Dolichospermum, Microcystis, Planktothricoides, Cyanobium, Pseudanabaena, and Synechococcus, increased in abundance following inferred historical nutrient enrichment. Nutrient concentrations and hydrologic conditions were further implicated as the dominant controls on communities based on Random Forest and generalized additive modeling statistical analyses. In particular, significant increases in lake hydraulic residence times after the construction of the Chaohu Dam were significantly associated with altered biological community structures. Further, phosphorus enrichment was positively associated with increased richness and diversity of these communities following the 1980s. In addition, effects from increased atmospheric temperatures on eukaryotic algal and cyanobacterial communities were apparent. Here, high-throughput sequencing analysis of sedimentary DNA allowed the inference of long-term biodiversity dynamics of Lake Chaohu. These results underscore the important impacts of anthropogenic activities and climate change on aquatic ecosystems at the decadal scale.

Variation in the diversity of semiaquatic bugs (Insecta: Heteroptera: Gerromorpha) in altered and preserved veredas

Veredas environments play a critical role on the perennialization of streams in the Cerrado Biome, but alterations to their physiognomies are becoming increasingly more common, which directly affects abiotic variation and the structure of biological communities. Our study evaluates the effect of abiotic variations and environmental alterations upon the abundance, richness, and composition of species of semiaquatic bugs, where we test whether there are significant differences in conserved and altered veredas. Species richness was higher on altered veredas and there was no difference in abundance between altered and preserved veredas. The composition of conserved veredas was more homogeneous. Five species were associated with altered veredas and one to conserved areas. There were abiotic changes in the veredas that affected the abundance, richness, and/or composition of Gerromorpha. Ease of access to soil usage and to water for farming activities and pasture might be the main factors contributing to the alteration of veredas in this region. Gerromorpha community structure was modified by the environmental passive in areas of veredas, thus allowing to measure the degree of alterations to these systems, being a useful tool for monitoring and conservation.

Characteristics of particulate organic matter within the photic water column: A case study across the fronts in the indian sector of the Southern Ocean

During austral summer 2012, seawater samples were collected from the upper 120 m of the water column, across the frontal zones in the Indian Ocean sector of the Southern Ocean. Suspended particulate organic matter from seawater was characterised, from its organic carbon and nitrogen content, and δ13C(POM). There was a marked difference in δ13C(POM) across the three frontal zones. It was depleted from the Subtropical frontal zone (−24.48 ± 1.94‰) to the Subantarctic frontal zone (−25.53 ± 0.62‰) and the Polar frontal zone (−26.69 ± 1.22‰). Within the water column, Particulate Organic Carbon (POC) and Particulate Nitrogen (PN) decreased with depth, especially below the deep chlorophyll maxima. Principal Component Analysis of δ13C(POM) and the environmental variables showed two clusters, one cluster, within the Subtropical and Subantarctic frontal zones, whereas the other cluster was in the Polar frontal zone. Statistical analysis of δ13C with particulate organic carbon, nitrogen, apparent oxygen utilization, chlorophyll a and phytoplankton community, indicated that biological community structure strongly influenced the particulate organic matter characteristics in the upper water column. The study also revealed that both autotrophic and heterotrophic processes play a significant role in the waters of the Subtropical and Subantarctic frontal zones. Furthermore, physical factors like eddies and advection influence the community structure and food web dynamics of the region. However, in the Polar frontal zone, autotrophic processes were dominant, supported by the abundance of nutrients and prevalence of larger phytoplankton community (diatoms).

A multifaceted approach to analyzing taxonomic, functional, and phylogenetic β diversity.

Ecological literature offers a myriad of methods for quantifying β diversity. One such method is determining BDtotal (BD), which, unlike other methods, can be decomposed into meaningful components that indicate how unique a sampling unit is regarding its composition (local contribution) and how unique a species is regarding its occurrence in the community (species contribution). Despite this advantage, the original formulation of the BD metric only assesses taxonomic variation and neglects other important dimensions of biodiversity. We expanded the original formulation of BD to capture variation in the functional and phylogenetic dimensions of community data by computing two new metrics-BDFun and BDPhy -as well as their respective components that represent the local and species contribution. We tested the statistical performance of these new metrics for capturing variation in functional and phylogenetic composition through simulated communities and illustrated the potential use of these new metrics by analyzing β diversity of stream fish communities. Our results demonstrated that BDPhy and BDFun have acceptable type I error and great power to detect the effect of deep evolutionary relationships and attributes mediating patterns of β diversity. The empirical example illustrated how BDPhy and BDFun reveal complementary aspects of β diversity relative to the original BD metric. These new metrics can be used to identify local communities that are of conservation importance because they represent unique functional, phylogenetic, and taxonomic compositions. We conclude that BDPhy and BDFun are important tools for providing complementary information in the investigation of the structure of biological communities.

Variable niche breadth in benthic diatoms: Implications of ecological specialization and generalization for community structure

The mechanisms that regulate the composition and structure of biological communities remain poorly understood. Diatom communities have traditionally been assumed to be a collection of r-selected, ecologically redundant generalist taxa with distributions constrained largely by dispersal limitation. Here, we challenge this notion by presenting a novel model that uses distributional data to estimate ecological specialization for groups of diatom taxa. We further develop this model to evaluate relationships among ecological specialization, taxonomic richness, and species’ abundance using field data collected from ancient Lake Matano and the broader Malili Lakes system (Sulawesi, Indonesia), as well as Mazinaw Lake (Ontario, Canada). We demonstrated that diatom niche breadth is highly variable both at the assemblage scale and among genera within assemblages. Ecologically-specialized genera exhibited higher taxonomic richness than their generalist counterparts, suggesting that ecological specialization serves to support the sympatric coexistence of multiple species by limiting competitive interactions among congeneric taxa. This assertion is further supported by species’ abundance patterns, which suggested that resources are evenly partitioned among taxa within specialist genera, while less-specialized genera are composed of taxa with either exceptionally high or exceptionally low abundances reflective of their relative success in competitive interactions with one another. Our findings indicate that the often-overlooked complement of rare taxa within diatom assemblages are in fact the entities that respond most sensitively to environmental conditions and are worthy of far greater consideration in environmental assessment and paleolimnological studies.

Integration of biophysical connectivity in the spatial optimization of coastal ecosystem services

Ecological connectivity in coastal oceanic waters is mediated by dispersion of the early life stages of marine organisms and conditions the structure of biological communities and the provision of ecosystem services. Integrated management strategies aimed at ensuring long-term service provision to society do not currently consider the importance of dispersal and larval connectivity. A spatial optimization model is introduced to maximise the potential provision of ecosystem services in coastal areas by accounting for the role of dispersal and larval connectivity. The approach combines a validated coastal circulation model that reproduces realistic patterns of larval transport along the coast, which ultimately conditions the biological connectivity and productivity of an area, with additional spatial layers describing potential ecosystem services. The spatial optimization exercise was tested along the coast of Central Chile, a highly productive area dominated by the Humboldt Current. Results show it is unnecessary to relocate existing management areas, as increasing no-take areas by 10% could maximise ecosystem service provision, while improving the spatial representativeness of protected areas and minimizing social conflicts. The location of protected areas was underrepresented in some sections of the study domain, principally due to the restriction of the model to rocky subtidal habitats. Future model developments should encompass the diversity of coastal ecosystems and human activities to inform integrative spatial management. Nevertheless, the spatial optimization model is innovative not only for its integrated ecosystem perspective, but also because it demonstrates that it is possible to incorporate time-varying biophysical connectivity within the optimization problem, thereby linking the dynamics of exploited populations produced by the spatial management regime.

Characterizing the phytoplankton and zooplankton communities in Kootenay Lake: a time series analysis of 24 years of nutrient addition

Large-scale seasonal addition of limiting nutrients has been used for restoration in Kootenay Lake, British Columbia, since 1992 to mitigate cultural oligotrophication resulting from upstream hydropower development, river channelization, mysid shrimp introduction, and extensive tributary floodplain loss. Historical (1949) in-lake nutrient levels were targeted to stimulate bottom-up carbon transfer from native plankton communities to planktivorous and piscivorous fish populations that support popular fisheries. Analysis of 24 years of monitoring data assessed the effects of nutrient addition on the phytoplankton and zooplankton communities. Assessment involved comparisons of plankton community metric data from North Arm (1992–2003) and North + South arms (2004–2015) nutrient addition periods. A before–after, control–impact (BACI) analysis adjusted for these effects involved a series of phytoplankton and zooplankton metrics across the two lake arms. Time series analyses revealed significant serial correlation structure, significant increases in phytoplankton and zooplankton abundance and biomass, and increased stability within the phytoplankton and zooplankton communities. Results confirmed that adaptively managed nutrient restoration can effectively restore biological productivity and community structure in a large culturally oligotrophic lake.

Macroinvertebrate community responses to land use: a trait-based approach for freshwater biomonitoring in Mongolia

Land-use practices in Mongolia can lead to environmental degradation and consequently affect the structure and function of biological communities. The main aim of this study was to determine land-use effects on freshwater macroinvertebrate communities based on their response to grazing and mining, using a trait-based approach (TBA). The functional structure of macroinvertebrate communities was examined using 86 categories of 16 traits. A total of 13 physical and chemical variables were significantly different among the levels of land-use intensity. Significant declines in functional diversity were observed with increased land-use intensity. The community weighted mean of 19 trait categories for 11 traits varied significantly among different levels of land-use intensity. Traits were significantly explained by environmental variables across a land-use intensity gradient. Water temperature, gravel, nitrate, silt, and cobble were the main predictor variables and explained 28% of the total variance of the trait variation. The functional structure of the macroinvertebrate community was strongly related to environmental conditions. The TBA is an important method in assessing disturbance responses in freshwater communities of steppe and taiga regions, such as in Mongolia and other countries in Central Asia and will be useful in finding best management practices for conserving aquatic ecosystems.

Intensive land uses modify assembly process and potential metabolic function of edaphic bacterial communities in the Yellow River Delta, China

Coastal reclamation is a global threat to natural ecosystems, disturbing biological community structure, diversity and ecological function through habitat conversion. We have limited insights into the changes brought about by coastal reclamation for different land-use types. We used the Yellow River Delta (YRD) as a model because it is a region with intensive land reclamation, and we investigated the structural and functional variations of bacterial communities and their relations to edaphic properties under different land-use types. Our results showed that the high soil organic carbon (SOC), nitrate concentrations and salinity were found in oil field, aquaculture pond and salt pan, respectively, and low values in natural wetland. Land use was found to have significant influence on bacterial community diversity. To investigate the phylogenetic conservation of specific traits, we analyzed the relationship between soil bacterial assembly processes and edaphic properties. Bacterial traits phylogenetically conserved, and differs in depth. Our findings suggest that SOC served as a deep trait due to it negative correlation with deeper branches of phylogenetic clustering, while nitrate functioned as a shallow trait due to its positive correlation with phylogenetic clustering at finer branches. Soil salinity acted as a complex trait effected on both finer and deeper branches. Further potential functional gene co-occurrence network analysis revealed that land reclamation induced shifts of metabolic function by altering the functional gene connectivity. We found that the photosynthesis pathway was enriched in hub modules related to oil field (OF), while methane metabolism was enriched in hub modules linked to sea cucumber pond (CP1). In addition, two-component systems (TCS) were enriched with nitrate, ammonia, SOC and salinity-related modules. Therefore, our study highlights the importance of integrating multi-function and multi-process identification and prediction of coastal diverse reclamation impacts on coastal ecosystems.

Measuring and Linking the Missing Part of Biodiversity and Ecosystem Function: The Diversity of Biotic Interactions

Biotic interactions are part of all ecosystem attributes and play an important role in the structure and stability of biological communities. In this study, we give a brief account of how the threads of biotic interactions are linked and how we can measure such complexity by focusing on mutualistic interactions. We start by explaining that although biotic interactions are fundamental ecological processes, they are also a component of biodiversity with a clear α, β and γ diversity structure which can be measured and used to explain how biotic interactions vary over time and space. Specifically, we explain how to estimate the α-diversity by measuring the properties of species interaction networks. We also untangle the components of the β-diversity and how it can be used to make pairwise comparisons between networks. Moreover, we move forward to explain how local ecological networks are a subset of a regional pool of species and potential interactions, γ-diversity, and how this approach allows assessing the spatial and temporal dynamics of ecological networks. Finally, we propose a new framework for studying interactions and the biodiversity–ecosystem function relationship by identifying the unique and common interactions of local networks over space, time or both together.