Differential microplastic contamination of waterbirds in a coastal region associated with trophic groups and spatial distribution.

AimDespite recent calls for integrating interaction networks into the study of large‐scale biodiversity patterns, we still lack a basic understanding of the functional characteristics of large interaction networks and how they are structured across environments. Here, building on recent advances in network science around the Eltonian niche concept, we aim to characterize the trophic groups in a large food web, and understand how these trophic groups vary across space.LocationEurope and Anatolia.TaxonTetrapods (1,136 species).MethodsWe combined an expert‐based metaweb of all European tetrapods with their spatial distributions and biological traits. To understand the functional structure of the metaweb, we first used a stochastic block model to group species with similar Eltonian niches, and then analysed these groups with species’ functional traits and network metrics. We then combined these groups with species distributions to understand how trophic diversity varies across space, in function of the environment, and between the European ecoregions.ResultsWe summarized the 1,136 interacting species within the metaweb into 46 meaningful trophic groups of species with a similar role in the metaweb. Specific aspects of the ecology of species, such as their activity time, nesting habitat and diet explained these trophic groups. Across space, trophic diversity was driven by both biotic and abiotic factors (species richness, climate and primary productivity), and the representation of trophic groups differed among European ecoregions.Main conclusionsWe have characterized the Eltonian niche of species in a large food web, both in terms of species interactions and functional traits, and then used this to understand the spatial variation of food webs at a functional level, thus bringing together network science, functional ecology and biogeography. Our results highlight the need to integrate multiple aspects of species ecology in global change research. Further, our approach is strongly relevant for conservation biology as it could help predict the impact of species translocations on trophic diversity.

Impact of trophic ecologies on the whereabouts of nematodes in soil

The aim of this study was to determine the effect of pesticides on free-living soil nematodes in a desert system. Spatial and temporal distributions as well as changes in nematode community structure were investigated. Soil samples were collected monthly between November 2000 and November 2001 from four plots: one treated with Nemacur, one with Edigan, one with water and one untreated plot as control. The nematode population as well as spatial distribution was found to be affected by treatments on a temporal basis. The different treatments applied led to a significant difference in the abundance of nematode trophic groups, where the fungivores and bacterivores were found to decrease in the pesticide-treated samples. A total of 31 genera were found in the samples, with 21 in the Nemacur-treated sample and 16 in the Edigan-treated sample. Ecological indices such as trophic diversity, maturity index and Shannon index elucidated the effect of pesticides on density, diversity and trophic group composition.

Both trophic structure and biomass flow within marine food webs are influenced by the abiotic environment and anthropogenic stressors such as fishing. The abiotic environment has a large effect on species spatial distribution patterns and productivity and, consequently, spatial co-occurrence between predators and prey, while fishing alters species abundances and food-web structure. In order to disentangle the impacts of the abiotic environment and fishing in the Celtic Sea ecosystem, we developed a spatio-temporal trophic model, specifically an Ecopath with Ecosim with Ecospace model, for the period 1985–2016. In this model, particular attention was paid to the parameterization of the responses of all trophic levels to abiotic environmental changes. Satellite remote sensing data were employed to determine the spatial distribution and annual fluctuations of primary production (PP). Spatial and temporal changes in the habitat favorable for zooplankton were predicted with a novel ecological-niche approach using daily detection of productivity fronts from satellite ocean color. Finally, functional responses characterizing the effect of several abiotic environmental variables (including, among others, temperature, salinity and dissolved oxygen concentration, both at the surface and at the bottom) on fish species groups’ habitat suitability were produced from the predictions of statistical habitat models fitted to presence-absence data collected by multiple fisheries-independent surveys. The dynamic component of our model (Ecosim) was driven by time-series of fishing effort, PP, zooplankton habitat suitability and abiotic environmental variables, and was fitted to abundance and fisheries catch data. The spatial component of our model (Ecospace) was constructed, for specific years of the period 1985–2016 with contrasted abiotic environmental conditions, to predict the variable distribution of the biomass of all functional groups. We found that fishing was the main driver of observed ecosystem changes in the Celtic Sea over the period 1985–2016. However, the integration of the environmental variability into the model and the subsequent improvement of the fit of the dynamic Ecosim component highlighted (i) the control of the overall pelagic production by PP and (ii) the influence of temperature on the productivity of several trophic levels in the Celtic Sea, especially on trophic groups with warm and cold water affinities. In addition, Ecospace predictions indicated that the spatial distributions of commercial fish species may have substantially changed over the studied period. These spatial changes mainly appeared to be driven by temperature and may, therefore, largely impact future fisheries given the continuity of climatic changes.

Predicting which species will occur together in the future, and where, remains one of the greatest challenges in ecology, and requires a sound understanding of how the abiotic and biotic environments interact with dispersal processes and history across scales. Biotic interactions and their dynamics influence species' relationships to climate, and this also has important implications for predicting future distributions of species. It is already well accepted that biotic interactions shape species' spatial distributions at local spatial extents, but the role of these interactions beyond local extents (e.g. 10 km2 to global extents) are usually dismissed as unimportant. In this review we consolidate evidence for how biotic interactions shape species distributions beyond local extents and review methods for integrating biotic interactions into species distribution modelling tools. Drawing upon evidence from contemporary and palaeoecological studies of individual species ranges, functional groups, and species richness patterns, we show that biotic interactions have clearly left their mark on species distributions and realised assemblages of species across all spatial extents. We demonstrate this with examples from within and across trophic groups. A range of species distribution modelling tools is available to quantify species environmental relationships and predict species occurrence, such as: (i) integrating pairwise dependencies, (ii) using integrative predictors, and (iii) hybridising species distribution models (SDMs) with dynamic models. These methods have typically only been applied to interacting pairs of species at a single time, require a priori ecological knowledge about which species interact, and due to data paucity must assume that biotic interactions are constant in space and time. To better inform the future development of these models across spatial scales, we call for accelerated collection of spatially and temporally explicit species data. Ideally, these data should be sampled to reflect variation in the underlying environment across large spatial extents, and at fine spatial resolution. Simplified ecosystems where there are relatively few interacting species and sometimes a wealth of existing ecosystem monitoring data (e.g. arctic, alpine or island habitats) offer settings where the development of modelling tools that account for biotic interactions may be less difficult than elsewhere.

Primary production in terrestrial ecosystems is sustained by plants, microbiota, and fungi, which are the major organic matter providers in the root zone, setting in motion the soil food webs. Predators like soil amoebae voraciously feed on bacteria, fungi, and microbial eukaryotes releasing the nutrients sequestered in their biomass. Early food web setting up is crucial for seedling nutrition and its further development after establishment. Mycorrhizal fungi are more than phosphorus providers, and we wonder what their role is in structuring the predators' trophic groups in the root zone. We evaluated the effect of Rhizophagus intraradices inoculated in Zea mays (mycorrhizosphere), on the structuration of amoebae trophic groups along vertical and horizontal (3, 6, and 9cm) soil distribution when compared to un-inoculated plants, after 20days in microcosms. Amoebae species richness was highest in non-mycorrhizal seedlings in the root zone at 6- to 9-cm depth, and 3cm away from plants. More bacterial species are needed when plants are devoid of mycorrhiza, and their influence is constrained 3cm away from roots. Higher diversity of trophic groups was recorded at mycorrhizal seedlings and at the compartment influenced by the mycelium at 6- to 9-cm depth. The highest bacterivorous diversity, higher number of rare species and protozoa-eating amoebae, and the absence of fungivorous group recorded at the mycorrhizosphere of Z. mays, indicate that the community was very different from the non-mycorrhizal plants. We conclude that the arbuscular mycorrhizal fungus exerts significant changes on the community of trophic groups of amoebae.

Geographical gradients of patterns of species associations in ecological communities are largely unknown. Previous evidence indicated nested community assembly — caused mainly by unequal colonization probabilities and habitat capacity — and a tendency towards negative species associations in arid and tropical plant and animal communities. Patterns of community assembly in arctic environments are poorly studied. Here we use a data set on arctic plant and animal species obtained from arctic islands of the Kandalaksha Bay (White Sea), to infer patterns of species association across taxa and trophic groups. We performed co-occurrence and nestedness analyses to study patterns of community assembly and diversity of 1109 plant and animal species grouped according to taxa, dispersal ability, and ecological guild membership. Twelve out of 50 (24%) sufficiently species-rich families and orders on the environmentally relatively stable forested islands showed significantly negative species associations (segregation), while this proportion decreased to less than 13% on less stable heath, rocky, and sea-shore islands. Segregation was not linked to spatial species turnover across islands. Species richness of plants and animals decreased at higher levels of disturbance. We detected evidence for a gradient in species richness and ecological interactions from the most disturbed sea-shore and rocky islands to more stable forested islands. Species spatial distributions appeared to be largely random, in contrast to previous meta-analyses that used mainly communities at lower latitudes. We speculate that in arctic environments spatial turnover of species (vicariant segregation) is of less importance than turnover-independent (checkerboard) segregation. Our data support the view that ecological assemblages in high-latitude environments are less structured by ecological interactions than comparable assemblages in lower latitudes. We also add to the evidence that environmental disturbance regimes work against stable community structures. We notice the need for a formal meta-analysis on latitudinal trends in community structure.

The distribution of preimaginal stages of amphibiotic insects (mayflies, stoneflies, caddisflies, and black flies) in the running waters of the mountain-steppe landscapes of western Tuva has been investigated. The basin of the Hemchik River is 500–2200 meters above sea level. The taxonomic composition and spatial distribution are determined; higlnnountain, middle- mountain and low-nountain plain types of communities are detailed. The trophic structure of amphibiotic communities is analyzed along the ecological profiles from the upper to the lower reaches of the rivers.

The title of this volume mentions only the spatial patterns of plankton, but the populations we are concerned with have other types of variation which cannot be ignored. They have different life spans which must have an effect on their spatial distributions. Also, we must consider the food chain relations between organisms as a factor affecting spatial structure and this involves aspects such as the size distribution of the plants and animals and the numbers of different species within each trophic grouping.

Ridge‐and‐runnel systems are common morphological features across the intertidal zone of dissipative macrotidal beaches. However, these systems have often been overlooked by macrofaunal zonation studies. The present study investigated the effects of this system on the spatial distribution of the macrofaunal community on an Amazonian macrotidal sandy beach. Samples (macrobenthos and sediments) were collected at seven equidistant levels (50 m apart) from the high tide water mark to the swash zone, in two different areas: (1) with and (2) without ridge‐and‐runnel systems. The results showed a significant increase in macrofaunal abundance and richness in area with runnels, associated with muddier sediment and higher organic content. The macrofauna in the runnels, both in upper‐intertidal and lower‐intertidal zones, had higher density and richness than that in the sandbars. There was no difference between tidal levels in area 2, although we observed an increasing tendency of abundance and richness towards the low tide line. Taxonomic composition and trophic groups also differed between areas, with predominance of species that are typical of sandy‐mud substrate and higher participation of nonselective deposit feeders in area 1. Predatory species typical of sandy substrates prevailed in area 2. These findings add knowledge to sandy beach ecology and indicate the importance of including aspects of habitat complexity in both across‐ and alongshore macrofaunal distribution studies.

Anthropogenic impacts in the nearshore fish community of the Yucatan Coastal Corridor. A comparison of protected and unprotected areas

We described the spatial distribution of fish trophic groups in the Agua Boa Stream, MS, Brazil. Specimens were caught using electrofishing in the upper, intermediate and lower stretches of the stream, between March and November 2008. We analyzed 415 stomach contents of 24 species. Detritus/sediment and aquatic invertebrates were the main exploited resources. Ordination analysis categorized the species in six trophic groups. Aquatic invertivores showed the highest richness (10 species), followed by detritivores (08 species), omnivores (03 species), terrestrial invertivores (03 species), algivores (02 species) and herbivore (01 species). Three trophic groups occurred in the upper stretch, six in the intermediate and five in the lower. Detritivores, omnivores and algivores showed the highest density, while detritivores and aquatic invertivores presented the highest biomass. Autochthonous resources were particularly important to the studied fish fauna, especially aquatic invertebrates, so, conservation actions reducing the simplification of the habitat by silting and recovering the riparian forest are essential to maintain the ichthyofauna of the Agua Boa Stream.

The spatial variability of total soil nematodes and trophic groups in bare and fallow plots in Shenyang Experimental Station of Ecology, Chinese Academy of Sciences was examined using geostatistics combined with classic statistics. Results showed that the soil pH value had a negative effect on plant-parasites in both bare and fallow plots; the mean number of total nematodes was significantly higher in fallow plots than in bare plots, which was 1485.3 and 464.0 individuals per 100 g dry soil in fallow and bare plots, respectively; the nugget (C0)/sill (C0+C) ratio of total nematodes, plant-parasites and bacterivores were lower in fallow plots (27.3%–45.6%) than in bare plots (49.5%–100%); the spatial distribution of total nematodes and trophic groups was found to be different between fallow and bare plots, which indicated that vegetation coverage had an effect on soil nematodes.

The importance of a functional approach on benthic communities for aquaculture environmental assessment: Trophic groups – A polychaete view

By the methods of classic statistics and geostatistics, this paper examined the spatial variability of soil nematodes and their trophic groups in bare and fallow plots at Shenyang Experimental Station of Ecology, Chinese Academy of Sciences. The results showed that soil pH had a negative effect on the plant-parasitic nematodes in both bare and fallow plots. The total number of soil nematodes was significantly higher in fallow than in bare plot, being 1 485.3 and 464.0 individuals per 100 g dry soil, respectively. The nugget (C0)/sill (C0 + C) ratio of total nematodes, plant-parasites and bacterivores were lower in fallow plot (27.3%-45.6%) than in bare plot (49.5%-100%). There was a significant difference in the spatial distribution of total nematodes and trophic groups between fallow and bare plots, indicating that vegetation coverage had an obvious effect on soil nematodes.