Climate change increases flowering duration, driving phenological reassembly and elevated co-flowering richness.

Changes to flowering phenology are a key response of plants to climate change. However, we know little about how these changes alter temporal patterns of reproductive overlap (i.e. phenological reassembly). We combined long-term field (1937-2012) and herbarium records (1850-2017) of 68 species in a flowering plant community in central North America and used a novel application of Bayesian quantile regression to estimate changes to flowering season length, altered richness and composition of co-flowering assemblages, and whether phenological shifts exhibit seasonal trends. Across the past century, phenological shifts increased species' flowering durations by 11.5 d on average, which resulted in 94% of species experiencing greater flowering overlap at the community level. Increases to co-flowering were particularly pronounced in autumn, driven by a greater tendency of late season species to shift the ending of flowering later and to increase flowering duration. Our results demonstrate that species-level phenological shifts can result in considerable phenological reassembly and highlight changes to flowering duration as a prominent, yet underappreciated, effect of climate change. The emergence of an autumn co-flowering mode emphasizes that these effects may be season-dependent.

Ecological restoration at pilot-scale employing site-specific rationales for small-patch degraded mangroves in Indian Sundarbans.

To date, degraded mangrove ecosystem restoration accomplished worldwide primarily aligns towards rehabilitation with monotypic plantations, while ecological restoration principles are rarely followed in these interventions. However, researchers admit that most of these initiatives' success rate is not appreciable often. An integrative framework of ecological restoration for degraded mangroves where site-specific observations could be scientifically rationalized, with co-located reference pristine mangroves as the target ecosystem to achieve is currently distinctively lacking. Through this experimental scale study, we studied the suitability of site-specific strategies to ecologically restore degraded mangrove patches vis-à-vis the conventional mono-species plantations in a highly vulnerable mangrove ecosystem in Indian Sundarbans. This comprehensive restoration framework was trialed in small discrete degraded mangrove patches spanning ~ 65 ha. Site-specific key restoration components applied are statistically validated through RDA analyses and Bayesian t-tests. 25 quantifiable metrics evaluate the restoration success of a ~ 3 ha degraded mangrove patch with Ridgeline distribution, Kolmogorov-Smirnov (K-S) tests, and Mahalanobis Distance (D2) measure to prove the site's near-equivalence to pristine reference in multiple ecosystem attributes. This restoration intervention irrevocably establishes the greater potential of this framework in the recovery of ecosystem functions and self-sustenance compared to that of predominant monoculture practices for vulnerable mangroves.

Ecological Groups of Coleoptera (Insecta) as Indicators of Habitat Transformation on Drained and Rewetted Peatlands: A Baseline Study from a Carbon Supersite, Kaliningrad, Russia.

A total of 281 coleopteran species from 41 families were recorded from different sites of an abandoned cut-over peatland designated as the Carbon Measurement Supersite in Kaliningrad Oblast. This beetle assemblage is considered a baseline (pre-impact) faunal assemblage for further investigations during the 'before-after' (BA) or 'before-after control-impact' (BACI) study on a peatland that is planned to be rewetted. The spontaneously revegetated peatland has a less specialised beetle assemblage than at an intact raised bog. Tyrphobiontic species are completely absent from the peatland, while some tyrphophiles (5.3% of the total beetle fauna) are still found as remnants of the former raised bog communities. The predominant coenotic coleopteran group is tyrphoneutral generalists from various non-bog habitats (72.9%). The species composition is associated with the vegetation structure of the disturbed peatland (fragmentary Sphagnum cover, lack of open habitats, and widespread birch coppice or tree stand), which does not correspond to that of a typical European raised bog. The sampled coleopteran assemblage is divided into several relative ecological groups, whose composition and peculiarities are discussed separately. Possible responses to the rewetting measurements in different coleopteran groups are predicted and briefly discussed. A complex assemblage of stenotopic peatland-specialised tyrphophiles (15 spp.) and the most abundant tyrphoneutral generalists (31 spp.) were assigned as indicators for the environmental monitoring of peatland development.

Tolerance to aerial exposure influences distributional patterns in multi-species intertidal seagrass meadows.

Multi-specific seagrass meadow assemblages dominate most tropical intertidal regions but the relative role of environmental stress in determining distribution patterns is still uncertain. Here we combine observational and experimental approaches to examine aerial exposure as a factor driving species occurrence patterns in intertidal meadows of the Andaman archipelago, where up to 6 seagrass species co-occur. In the studied meadow, patterns of exposure did not map onto distance from the coast, instead creating a patchy matrix of exposure, based on fine-scale bathymetric differences. Distributional surveys showed that seagrass species were similarly patchy, often tracking the degree of aerial exposure during low tide. While some species (Halophila ovalis, Halophila minor, and Thalassia hemprichii) frequently occurred in submerged or subtidal areas and were rarely found in completely exposed areas, other species (Cymodocea rotundata, Halophila beccarii, and Halodule uninervis) also occupied areas that were subject to partial or complete aerial exposure during low tide. To confirm this pattern, we used field-based transplant experiments, employing a natural gradient of tidal exposure to subject six seagrass species to different desiccation exposure times. After a month, H. beccarii and H. uninervis transplants survived in areas that sustained more than 3 h of aerial tidal exposure without significant mortality, compared with other species (H. ovalis, H. minor, T. hemprichii, C. rotundata) that showed dramatic shoot mortality at the same exposure regimes. For all species, 4 h represented the upper limit of exposure, in both experimental and distributional studies. However, despite their wider tolerance of exposure to air, H. beccarii and H. uninervis did not dominate the entire meadow. This could be a result either of their poor tolerance to other environmental factors or their lower competitive abilities among other mechanisms. This suggests that in tropical multi-specific meadows, strong environmental filters could override clear intertidal zonation to create patchy matrices based on species tolerances.

Biotic homogenisation and differentiation as directional change in beta diversity: synthesising driver-response relationships to develop conceptual models across ecosystems.

Biotic homogenisation is defined as decreasing dissimilarity among ecological assemblages sampled within a given spatial area over time. Biotic differentiation, in turn, is defined as increasing dissimilarity over time. Overall, changes in the spatial dissimilarities among assemblages (termed 'beta diversity') is an increasingly recognised feature of broader biodiversity change in the Anthropocene. Empirical evidence of biotic homogenisation and biotic differentiation remains scattered across different ecosystems. Most meta-analyses quantify the prevalence and direction of change in beta diversity, rather than attempting to identify underlying ecological drivers of such changes. By conceptualising the mechanisms that contribute to decreasing or increasing dissimilarity in the composition of ecological assemblages across space, environmental managers and conservation practitioners can make informed decisions about what interventions may be required to sustain biodiversity and can predict potential biodiversity outcomes of future disturbances. We systematically reviewed and synthesised published empirical evidence for ecological drivers of biotic homogenisation and differentiation across terrestrial, marine, and freshwater realms to derive conceptual models that explain changes in spatial beta diversity. We pursued five key themes in our review: (i) temporal environmental change; (ii) disturbance regime; (iii) connectivity alteration and species redistribution; (iv) habitat change; and (v) biotic and trophic interactions. Our first conceptual model highlights how biotic homogenisation and differentiation can occur as a function of changes in local (alpha) diversity or regional (gamma) diversity, independently of species invasions and losses due to changes in species occurrence among assemblages. Second, the direction and magnitude of change in beta diversity depends on the interaction between spatial variation (patchiness) and temporal variation (synchronicity) of disturbance events. Third, in the context of connectivity and species redistribution, divergent beta diversity outcomes occur as different species have different dispersal characteristics, and the magnitude of beta diversity change associated with species invasions also depends strongly on alpha and gamma diversity prior to species invasion. Fourth, beta diversity is positively linked with spatial environmental variability, such that biotic homogenisation and differentiation occur when environmental heterogeneity decreases or increases, respectively. Fifth, species interactions can influence beta diversity via habitat modification, disease, consumption (trophic dynamics), competition, and by altering ecosystem productivity. Our synthesis highlights the multitude of mechanisms that cause assemblages to be more or less spatially similar in composition (taxonomically, functionally, phylogenetically) through time. We consider that future studies should aim to enhance our collective understanding of ecological systems by clarifying the underlying mechanisms driving homogenisation or differentiation, rather than focusing only on reporting the prevalence and direction of change in beta diversity, per se.

Environmental filtering rather than dispersal limitation dominated plant community assembly in the Zoige Plateau.

Identifying the mechanisms that underlie the assembly of plant communities is critical to the conservation of terrestrial biodiversity. However, it is seldom measured or quantified how much deterministic versus stochastic processes contribute to community assembly in alpine meadows. Here, we measured the decay in community similarity with spatial and environmental distance in the Zoige Plateau. Furthermore, we used redundancy analysis (RDA) to divide the variations in the relative abundance of plant families into four components to assess the effects of environmental and spatial. Species assemblage similarity liner declined with geographical distance (p < .001, R 2 = .6388), and it decreased significantly with increasing distance of total phosphorus (TP), alkali-hydrolyzable nitrogen (AN), available potassium (AK), nitrate nitrogen (NO3 +-N), and ammonia nitrogen (NH4 +-N). Environmental and spatial variables jointly explained a large proportion (55.2%) of the variation in the relative abundance of plant families. Environmental variables accounted for 13.1% of the total variation, whereas spatial variables accounted for 11.4%, perhaps due to the pronounced abiotic gradients in the alpine areas. Our study highlights the mechanism of plant community assembly in the alpine ecosystem, where environmental filtering plays a more important role than dispersal limitation. In addition, a reasonably controlled abundance of Compositae (the family with the highest niche breadth and large niche overlap value with Gramineae and Cyperaceae) was expected to maintain sustainable development in pastoral production. These results suggest that management measures should be developed with the goal of improving or maintaining suitable local environmental conditions.

Predicting microbiome compositions from species assemblages through deep learning.

Microbes can form complex communities that perform critical functions in maintaining the integrity of their environment or their hosts' well-being. Rationally managing these microbial communities requires improving our ability to predict how different species assemblages affect the final species composition of the community. However, making such a prediction remains challenging because of our limited knowledge of the diverse physical, biochemical, and ecological processes governing microbial dynamics. To overcome this challenge, we present a deep learning framework that automatically learns the map between species assemblages and community compositions from training data only, without knowing any of the above processes. First, we systematically validate our framework using synthetic data generated by classical population dynamics models. Then, we apply our framework to data from in vitro and in vivo microbial communities, including ocean and soil microbiota, Drosophila melanogaster gut microbiota, and human gut and oral microbiota. We find that our framework learns to perform accurate out-of-sample predictions of complex community compositions from a small number of training samples. Our results demonstrate how deep learning can enable us to understand better and potentially manage complex microbial communities.

Landscape Composition Affects Elements of Metacommunity Structure for Culicidae Across South-Eastern Illinois.

The interplay among invasive alien vectors and the species assemblage of native potential vectors in areas of range expansion may affect the dynamics of pathogen transmission. In this study we investigate how Aedes albopictus, an invasive mosquito of considerable public health concern fits within mosquito communities at the edge of its range of distribution. This was addressed using a 2-year field survey of mosquitoes in south-eastern Illinois. We found that Ae. albopictus was more broadly distributed in this region than previously realized, with new occurrence records for nine counties. Abundance of this species varied strongly and peaked in locations of low-intermediate overall mosquito species richness. This differed from overall mosquito abundance, as well as abundance of another important vector, Cx. pipiens, for which the abundance-richness relationships were best described with power functions. Metacommunity analyses revealed that mosquito communities showed a non-random distribution with a Clementsian gradient, which suggests a pattern whereby distinct species assemblages are associated with specific habitats or environmental conditions. Land use was a significant underlying factor shaping mosquito community structure and species assemblages. Multivariate analyses showed that while Ae. canadensis and Cx. pipiens complex mosquitoes were associated with high and low proportions of wetlands in the environment, respectively, Ae. albopictus was most strongly associated with urban settlements. This work sheds light on landscape-level processes, such as niche differentiation driven by urban and agricultural development, structuring mosquito communities. We suggest that mosquito community assessments across habitats be incorporated as part of a One Health vector surveillance approach to aid in the goal of prediction and prevention of new and (re-)emerging vector-borne diseases.

Compartmentalized organization of ecological niche occupation in insular invertebrate communities.

Understanding the mechanisms of species distribution within ecosystems is a fundamental question of ecological research. The current worldwide changes and loss of habitats associated with a decline in species richness render this topic a key element for developing mitigation strategies. Ecological niche theory is a widely accepted concept to describe species distribution along environmental gradients where each taxon occupies its own distinct set of environmental parameters, that is, its niche. Niche occupation has been described in empirical studies for different closely related taxa, like ant, ungulate, or skink species, just to name a few. However, how species assemblages of whole ecosystems across multiple taxa are structured and organized has not been investigated thoroughly, although considering all taxa of a community would be essential when analyzing realized niches. Here, we investigated the organization of niche occupation and species distribution for the whole ground-associated invertebrate community of small tropical insular ecosystems. By correlating environmental conditions with species occurrences using partial canonical correspondence analysis (pCCA), we demonstrated that the ground-associated invertebrate community does not spread evenly across the overall niche space, but instead is compartmentalized in four distinct clusters: crustacean and gastropod taxa occurred in one cluster, attributable to the beach habitat, whereas hexapods and spider taxa occurred in three distinct inland clusters, attributable to distinct inland habitats, that is, grassland, open forest, and dense forest. Within the clusters, co-occurrence pattern analysis suggested only a few negative interactions between the different taxa. By studying ground-associated insular invertebrate communities, we have shown that species distribution and niche occupation can be, similar to food webs, organized in a compartmentalized way. The compartmentalization of the niche space might thereby be a mechanism to increase ecosystem resilience, as disturbances cascade more slowly throughout the ecosystem.

Towards a better understanding of shallow erosion resistance of subalpine grasslands.

Shallow erosion is caused by processes such as landsliding, snow gliding, avalanches, animal trampling, or human activities and frequently occurs on high mountain grasslands. It can lead to significant long-term losses of grassland and related ecosystem services, e.g. fodder production, or water retention. Since restoration of subalpine and alpine ecosystems is difficult, prevention of shallow erosion is of vital importance for damage control. However, current knowledge on relationships between grassland ecology, management and shallow erosion resistance is very limited. In this study, we assessed relationships between the surface-mat stability of the topsoil (0-10 cm depth), vegetation cover, species diversity, growth patterns, indicator plant species for high and low tensile strength, soil texture, total nitrogen, and soil organic carbon. Vegetation composition significantly influenced the surface-mat stability of subalpine grasslands. Some key species were associated with higher reinforcement than other species. However, surface-mat stability neither depended on the vegetation type (grass or forb), nor on the root type, but rather on individual species characteristics such as roots and clonal structures as well as a certain plant and structural diversity. A balanced nutrient supply was associated with higher surface-mat stability, while soil texture had no effect. We hypothesized that stabilizing effects of plant-plant connections in tightly interwoven, dense root and clonal structure systems dominate over effects of root-soil connections. Thus, effects of soil texture may be negligible for the surface-mat stability. In general, our results show that adapted grassland management can be used as preventive erosion control measure on subalpine grasslands.

Comparative metal analysis in a species assemblage of mammals from the Southeastern United States.

Metal pollution commonly occurs in many terrestrial environments and may pose a threat for the animals inhabiting such areas. Here, we present concentrations of six metals (cadmium [Cd], copper [Cu], nickel [Ni], lead [Pb], selenium [Se], and zinc [Zn]) in the liver tissues of seven species of mammals obtained from a study that examined the impact of mesopredator removal on northern bobwhite (Colinus virginianus) populations. A total of 1326 samples were collected from 2003 to 2006 at four sites in southwest Georgia and north Florida from nine-banded armadillos (Dasypus novemcinctus), bobcats (Lynx rufus), feral cats (Felis catus), coyotes (Canis latrans), grey foxes (Urocyon cinereoargenteus), opossums (Didelphis virginiana), and raccoons (Procyon lotor). Data from armadillos, bobcats, opossums, and raccoons were published previously to examine age, sex, spatial (between sites), and temporal (between years) variation. In this paper, we present similar comparisons for the remaining three species as well as comparisons of metal concentrations among all seven species. Concentrations of Cu and Pb exhibited strong negative relationships with body weight in coyotes, while Ni was positively correlated with weight in feral cats. Concentrations of these metals, as well as the other two tested (Cd and Zn), were not significantly correlated with one another in any of the three species. The only sex difference in liver metal concentrations was observed in female feral cats, which had higher levels of Pb than did males. Coyotes exhibited significant differences in Cu concentrations between sites and between years (2005 versus 2006). We also found significant differences between sites in Pb concentrations for both feral cats and grey foxes. There were significant differences in metal concentrations among all seven species for all metals except Cd. With the exception of Cd and Se (tested only in bobcats and opossums), a three-way ANOVA with species, year, and site as the three factors revealed significant differences among species for every metal but only a single main effect of year for Cu, and no main effects of site. In sum, our results provide an extensive survey of metal concentrations in a diverse assemblage of mammals and suggest that metal accumulation may be heavily influenced by species identity, which in turn may reflect ecological lifestyle.

How many submerged macrophyte species are needed to improve water clarity and quality in Yangtze floodplain lakes?

Successful re-establishment and maintenance of submerged macrophytes is a pivotal problem for the restoration of shallow eutrophic lakes, since submerged macrophytes can facilitate a shift of lake ecosystems from a turbid water state to a clear water state through their structuring roles. However, little is known about the optimal number of macrophyte species (species richness) needed for the recovery of shallow eutrophic lakes. Here, we investigated 19 shallow eutrophic lakes along the mid-lower reaches of the Yangtze River to reveal the underlying interrelations among water clarity, water quality and species richness. Our results showed positive correlations of water nutrients (TN and TP) with Kd and Red/Blue light ratio, suggesting that bad water quality can significantly lower water clarity. The results of path analysis indicated that the underwater light climate directly affects morphological and physiological traits and species richness of submerged macrophytes. Changes in functional traits also affected significantly the species richness of submerged macrophytes. Moreover, the presence of submerged macrophytes not only had positive effects on the underwater light climate (water clarity), but also on water quality. Most importantly, the assemblage of three or more submerged macrophyte species can significantly improve water clarity in these sampled eutrophic lakes, but not water quality. Additionally, the basic species assemblage of Myriophyllum spicatum and Vallisneria natans can be used for restoration of submerged macrophytes in shallow eutrophic Yangtze floodplain lakes. It is concluded that species richness and species assemblage are critical for recovery of submerged macrophytes in shallow eutrophic lakes.

Testing marine regional-scale hypotheses along the Yucatan continental shelf using soft-bottom macrofauna.

Different hypotheses related to the regional-scale configuration of the Yucatan Continental Shelf (YCS) between the Gulf of Mexico (GoM) and the Caribbean Sea have been proposed. Hypotheses regarding its regional boundaries include: (i) an ecoregional boundary at Catoche Cape, dividing the Western Caribbean and the Southern GoM ecoregions; and (ii) a boundary within the Southern GoM ecoregion at 89°W, separating the West and Mid-Yucatan areas. We tested the hypothesis of no variation in benthic macrofaunal assemblages between regions delimited by the former boundaries using the species and functional traits of soft-bottom macrofauna. We considered that the depth and temporal environmental dynamics might interact with regional variations, generating complex benthic community patterns. The data were collected over five years (2010-2012, 2015-2016) at 86 stations (N = 1, 017 samples, 10-270 m depth), comprising 1,327 species with 45 combinations of functional traits. The variation in species composition and functional trait assemblages were both consistent with the occurrence of three separate regions in the Yucatan Peninsula (West Yucatan, Mid-Yucatan and Western Caribbean). This regional configuration was consistent with changes in assemblage structure and depth zonation as well as temporal variation. Along with spatial and temporal variation, diversity diminished with depth and different regions exhibited contrasting patterns in this regard. Our results suggest that the spatial and temporal variation of soft-bottom macrofauna at YCS demonstrate the complex organization of a carbonate shelf encompassing different regions, which may represent transitional regions between the Caribbean and the GoM.

Climate change undermines the global functioning of marine food webs.

Sea water temperature affects all biological and ecological processes that ultimately impact ecosystem functioning. In this study, we examine the influence of temperature on global biomass transfers from marine secondary production to fish stocks. By combining fisheries catches in all coastal ocean areas and life-history traits of exploited marine species, we provide global estimates of two trophic transfer parameters which determine biomass flows in coastal marine food web: the trophic transfer efficiency (TTE) and the biomass residence time (BRT) in the food web. We find that biomass transfers in tropical ecosystems are less efficient and faster than in areas with cooler waters. In contrast, biomass transfers through the food web became faster and more efficient between 1950 and 2010. Using simulated changes in sea water temperature from three Earth system models, we project that the mean TTE in coastal waters would decrease from 7.7% to 7.2% between 2010 and 2100 under the 'no effective mitigation' representative concentration pathway (RCP8.5), while BRT between trophic levels 2 and 4 is projected to decrease from 2.7 to 2.3 years on average. Beyond the global trends, we show that the TTEs and BRTs may vary substantially among ecosystem types and that the polar ecosystems may be the most impacted ecosystems. The detected and projected changes in mean TTE and BRT will undermine food web functioning. Our study provides quantitative understanding of temperature effects on trophodynamic of marine ecosystems under climate change.

Functional richness shows spatial scale dependency in Pheidole ant assemblages from Neotropical savannas.

There is a growing recognition that spatial scale is important for understanding ecological processes shaping community membership, but empirical evidence on this topic is still scarce. Ecological processes such as environmental filtering can decrease functional differences among species and promote functional clustering of species assemblages, whereas interspecific competition can do the opposite. These different ecological processes are expected to take place at different spatial scales, with competition being more likely at finer scales and environmental filtering most likely at coarser scales. We used a comprehensive dataset on species assemblages of a dominant ant genus, Pheidole, in the Cerrado (savanna) biodiversity hotspot to ask how functional richness relates to species richness gradients and whether such relationships vary across spatial scales. Functional richness of Pheidole assemblages decreased with increasing species richness, but such relationship did not vary across different spatial scales. Species were more functionally dissimilar at finer spatial scales, and functional richness increased less than expected with increasing species richness. Our results indicate a tighter packing of the functional volume as richness increases and point out to a primary role for environmental filtering in shaping membership of Pheidole assemblages in Neotropical savannas. OPEN RESEARCH BADGES: This article has been awarded Open Materials, Open Data, Preregistered Research Designs Badges. All materials and data are publicly accessible via the Open Science Framework at https://doi.org/10.5061/dryad.31201jg.

Drivers of Phylogenetic Assemblage Structure of the Furnariides, a Widespread Clade of Lowland Neotropical Birds.

Species co-occurrence in local assemblages is shaped by distinct processes at different spatial and temporal scales. Here we focus on historical explanations and examine the phylogenetic structure of local assemblages of the Furnariides clade (Aves: Passeriformes), assessing the influence of diversification rates on the assembly and species co-occurrence within those assemblages. Using 120 local assemblages across Bolivia and Argentina and a nearly complete phylogeny for the clade, we analyzed assemblage phylogenetic structure, applying a recently developed model (DAMOCLES, or dynamic assembly model of colonization, local extinction, and speciation) accounting for the historical processes of speciation, colonization, and local extinction. We also evaluated how diversification rates determine species co-occurrence. We found that the assembly of Furnariides assemblages can be explained largely by speciation, colonization, and local extinction without invoking current local species interactions. Phylogenetic structure of open habitat assemblages mainly showed clustering, characterized by faster rates of colonization and local extinction than in forest habitats, whereas forest habitat assemblages were congruent with the model's equal rates expectation, thus highlighting the influence of habitat preferences on assembly and co-occurrence patterns. Our results suggest that historical processes are sufficient to explain local assemblage phylogenetic structure, while there is little evidence for species ecological interactions in avian assemblage diversity and composition.

Small but with big impact? Ecotoxicological effects of a municipal wastewater effluent on a small creek.

Municipal wastewater treatment plants (WWTPs) discharge micropollutants like pharmaceuticals, pesticides, personal care products or endocrine disrupting chemicals but also nutrients. Both can adversely influence the freshwater ecosystem and may finally affect the ecological conditions. Many studies focus on the potential impact of large WWTPs even if smaller ones are more common, often less efficient and discharge into small creeks or the upper reaches of rivers. As a result, the receiving waters are characterized by relatively high shares of treated wastewater. Thus, the primary objective of this study was to investigate the ecotoxicological effects of a small WWTP on freshwater amphipods and mollusks in a small creek using an active and passive monitoring approach, accompanied by laboratory experiments (LE). In vitro assays with recombinant yeasts and the microtox assay with Aliivibrio fischeri were performed in parallel to determine the endocrine potential and the baseline toxicity. The evaluation of the effects of the analysed WWTP was possible due to its shutdown during our study and the application of the same in vivo and in vitro assays before and after the shutdown. During the operation of the WWTP the discharge of treated wastewater caused significantly higher mortalities and lower reproduction of the anaylsed invertebrates in the active and passive montoring as well as in the LEs. Furthermore, the amphipod species assemblage in the creek was affected downstream of the WWTP effluent. Besides, the endocrine activity and baseline toxicity were significantly higher downstream of the effluent. After the shutdown of the WWTP, the in vitro activity levels and adverse in vivo effects in the receiving water recovered quickly with no significant differences downstream of the former WWTP effluent compared to the upstream station. Furthermore, the previously disturbed amphipod species assemblage recovered significantly with a shift in favor of Gammarus fossarum downstream of the effluent. These biological results are consistent with a marked decline by 81.5% for the detected micropollutants in the receiving creek after the shutdown which points to a prominent role of micropollutants for the observed effects.

Productivity and species richness in longleaf pine woodlands: resource-disturbance influences across an edaphic gradient.

This study examines the complex feedback mechanisms that regulate a positive relationship between species richness and productivity in a longleaf pine-wiregrass woodland. Across a natural soil moisture gradient spanning wet-mesic to xeric conditions, two large scale manipulations over a 10-yr period were used to determine how limiting resources and fire regulate plant species diversity and productivity at multiple scales. A fully factorial experiment was used to examine productivity and species richness responses to N and water additions. A separate experiment examined standing crop and richness responses to N addition in the presence and absence of fire. Specifically, these manipulations addressed the following questions: (1) How do N and water addition influence annual aboveground net primary productivity of the midstory/overstory and ground cover? (2) How do species richness responses to resource manipulations vary with scale and among functional groups of ground cover species? (3) How does standing crop (including overstory, understory/midstory, and ground cover components) differ between frequently burned and fire excluded plots after a decade without fire? (4) What is the role of fire in regulating species richness responses to N addition? This long-term study across a soil moisture gradient provides empirical evidence that species richness and productivity in longleaf pine woodlands are strongly regulated by soil moisture. After a decade of treatment, there was an overall species richness decline with N addition, an increase in richness of some functional groups with irrigation, and a substantial decline in species richness with fire exclusion. Changes in species richness in response to treatments were scale-dependent, occurring primarily at small scales (≤10 m2 ). Further, with fire exclusion, standing crop of ground cover decreased with N addition and non-pine understory/midstory increased in wet-mesic sites. Non-pine understory/midstory standing crop increased in xeric sites with fire exclusion, but there was no influence of N addition. This study highlights the complexity of interactions among multiple limiting resources, frequent fire, and characteristics of dominant functional groups that link species richness and productivity.

Relative importance of habitat filtering and limiting similarity on species assemblages of alpine and subalpine plant communities.

This study examined how habitat filtering and limiting similarity affect species assemblages of alpine and subalpine plant communities along a slope gradient on Mt. Norikura in central Japan. Plant traits (plant height, individual leaf area, specific leaf area (SLA), leaf linearity, leaf nitrogen and chlorophyll concentrations) and abiotic environmental factors (elevation, slope inclination, ground surface texture, soil water, soil pH, soil nutrient concentrations of NH4-N and NO3-N) were examined. The metrics of variance, range, kurtosis and the standard deviation of neighbor distance divided by the range of traits present (SDNDr) were calculated for each plant trait to measure trait distribution patterns. Limiting similarity was detected only for chlorophyll concentration. By contrast, habitat filtering was detected for individual leaf area, SLA, leaf linearity, chlorophyll concentration. Abiotic environmental factors were summarized by the principal component analysis (PCA). The first PCA axis positively correlated with elevation and soil pH, and negatively correlated with sand cover, soil water, NH4-N and NO3-N concentrations. High values of the first PCA axis represent the wind-exposed upper slope with lower soil moisture and nutrient availabilities. Plant traits changed along the first PCA axis. Leaf area, SLA and chlorophyll concentration decreased, and leaf linearity increased with the first PCA axis. This study showed that the species assemblage of alpine and subalpine plants was determined mainly by habitat filtering, indicating that abiotic environmental factors are more important for species assemblage than interspecific competition. Therefore, only species adapting to abiotic environments can distribute to these environments.

Influence of the water quality improvement on fish population in the Seine River (Paris, France) over the 1990-2013 period.

Over the past 20 years, rules concerning wastewater treatment and quality of water discharged into the environment have changed considerably. Huge investments have been made in Paris conurbation to improve waste water treatment processes in accordance with the European Water Framework Directive. The interdepartmental association for sewage disposal in Paris conurbation (SIAAP) carried out a monitoring of both fish assemblages and water quality in the Seine River around the Paris conurbation (France) since the early 90's. The main goal of this study was to estimate the influence of the water quality improvement on fish. On one hand, the study confirmed the improvement of the water quality (dissolved oxygen, ammonia nitrogen, organic matter) in the Seine River, mostly focused downstream of Paris conurbation. On the other hand, an increase of the number of species occurred from 1990 (14) to 2013 (21). Moreover, changes in the river Seine assemblages happened over that 23-year period with emergence of sensitive species (ruffe, scalpin and pike-perch). The improvement of the water quality was also reported with respect to the Index of Biotic Integrity (IBI). However, no variation of pollutant concentrations in roach, eel and chub muscles has been observed. An exceedance of the environmental quality standards have even been reported all over this period as regards mercury and organochlorine.