Body size is intrinsically linked to metabolic rate and life-history traits, and is a crucial determinant of food webs and community dynamics. The increased temperatures associated with the urban-heat-island effect result in increased metabolic costs and are expected to drive shifts to smaller body sizes . Urban environments are, however, also characterized by substantial habitat fragmentation , which favours mobile species. Here, using a replicated, spatially nested sampling design across ten animal taxonomic groups, we show that urban communities generally consist of smaller species. In addition, although we show urban warming for three habitat types and associated reduced community-weighted mean body sizes for four taxa, three taxa display a shift to larger species along the urbanization gradients. Our results show that the general trend towards smaller-sized species is overruled by filtering for larger species when there is positive covariation between size and dispersal, a process that can mitigate the low connectivity of ecological resources in urban settings . We thus demonstrate that the urban-heat-island effect and urban habitat fragmentation are associated with contrasting community-level shifts in body size that critically depend on the association between body size and dispersal. Because body size determines the structure and dynamics of ecological networks , such shifts may affect urban ecosystem function.

1. Aquatic plants are a key component of spatial heterogeneity in a waterscape, contributing to habitat complexity and helping determine diversity at various spatial scales. Theoretically, the more complex a habitat, the higher the number of species present. 2. Few empirical data are available to test the hypothesis that complexity increases diversity in aquatic communities (e.g. Jeffries, 1993). Fractal dimension has become widely applied in ecology as a tool to quantify the degree of complexity at different scales. 3. We investigated the hypothesis that complexity in vegetated habitat in two tropical lagoons mediates littoral invertebrate number of taxa (S) and density (N). Aquatic macrophyte habitat complexity was defined using a fractal dimension and a gradient of natural plant complexities. We also considered plant area, plant identity and, only for S, invertebrate density as additional explanatory variables. 4. Our results indicate that habitat complexity provided by the different architectures of aquatic plants, significantly affects both S and total N. However, number of individuals (as a result of passive sampling) also helps to account for S and, together with plant identity and area, contributes to the determination of N. We suggest that measurements of structural complexity, measured through fractal geometry, should be included in studies aimed at explaining attributes of attached invertebrates at small (e.g. plant or leaf) scales.

The increasing urbanization process is hypothesized to drastically alter (semi‐)natural environments with a concomitant major decline in species abundance and diversity. Yet, studies on this effect of urbanization, and the spatial scale at which it acts, are at present inconclusive due to the large heterogeneity in taxonomic groups and spatial scales at which this relationship has been investigated among studies. Comprehensive studies analysing this relationship across multiple animal groups and at multiple spatial scales are rare, hampering the assessment of how biodiversity generally responds to urbanization. We studied aquatic (cladocerans), limno‐terrestrial (bdelloid rotifers) and terrestrial (butterflies, ground beetles, ground‐ and web spiders, macro‐moths, orthopterans and snails) invertebrate groups using a hierarchical spatial design, wherein three local‐scale (200 m × 200 m) urbanization levels were repeatedly sampled across three landscape‐scale (3 km × 3 km) urbanization levels. We tested for local and landscape urbanization effects on abundance and species richness of each group, whereby total richness was partitioned into the average richness of local communities and the richness due to variation among local communities. Abundances of the terrestrial active dispersers declined in response to local urbanization, with reductions up to 85% for butterflies, while passive dispersers did not show any clear trend. Species richness also declined with increasing levels of urbanization, but responses were highly heterogeneous among the different groups with respect to the richness component and the spatial scale at which urbanization impacts richness. Depending on the group, species richness declined due to biotic homogenization and/or local species loss. This resulted in an overall decrease in total richness across groups in urban areas. These results provide strong support to the general negative impact of urbanization on abundance and species richness within habitat patches and highlight the importance of considering multiple spatial scales and taxa to assess the impacts of urbanization on biodiversity.

1. It is widely acknowledged that sudden, large-scale flood pulses are drivers of benthic and planktonic biodiversity change in floodplains. The impact of such pulses on pleuston (biotic communities associated with root systems of floating plants) remains to be demonstrated. Here, we investigate the effects of local and regional drivers on seasonal changes in abundance and diversity of ostracod communities in pleuston. 2. Temporal and spatial distribution patterns of species richness, abundance, diversity and evenness of ostracods associated with the floating water hyacinth, Eichhornia crassipes, in a lentic environment from the upper Paraná River floodplain, were investigated in relation to local, as well as regional, environmental factors. Ostracods were sampled monthly over an annual cycle (March 2004-February 2005. Twenty-seven species were found, representing the families Cyprididae, Candonidae, Limnocytheridae and Darwinulidae. Both diversity and abundance of ostracod communities showed seasonal changes, although species turn-over during the year was limited. 3. We tested two hypotheses concerning the causality of these fluctuations: seasonal recruitment and influx of allochthonous ostracods during the flood pulse. Our results indicate that seasonal recruitment is more likely to be the driver of fluctuations in relation to the flood pulse. We postulate that pleuston communities are buffered against possible detrimental effects of flood pulses.

a global database for metacommunity ecology, integrating species, traits, environment and space alienor Jeliazkov et al. #the use of functional information in the form of species traits plays an important role in explaining biodiversity patterns and responses to environmental changes. although relationships between species composition, their traits, and the environment have been extensively studied on a case-by-case basis, results are variable, and it remains unclear how generalizable these relationships are across ecosystems, taxa and spatial scales. to address this gap, we collated 80 datasets from trait-based studies into a global database for metaCommunity Ecology: Species, Traits, Environment and Space; "CEStES". Each dataset includes four matrices: species community abundances or presences/absences across multiple sites, species trait information, environmental variables and spatial coordinates of the sampling sites. the CEStES database is a live database: it will be maintained and expanded in the future as new datasets become available. By its harmonized structure, and the diversity of ecosystem types, taxonomic groups, and spatial scales it covers, the CEStES database provides an important opportunity for synthetic trait-based research in community ecology. Background & SummaryA major challenge in ecology is to understand the processes underlying community assembly and biodiversity patterns across space 1,2 . Over the three last decades, trait-based research, by taking up this challenge, has drawn increasing interest 3 , in particular with the aim of predicting biodiversity response to environment. In community ecology, it has been equated to the 'Holy Grail' that would allow ecologists to approach the potential processes underlying metacommunity patterns 4-7 . In macroecology, it is common to study biodiversity variation through its taxonomic and functional facets along gradients of environmental drivers 8-10 . In biodiversity-ecosystem functioning research, trait-based diversity measures complement taxonomic ones to predict ecosystem functions 11 offering early-warning signs of ecosystem perturbation 12 .The topic of Trait-Environment Relationships (TER) has been extensively studied across the globe and across the tree of life. However, each study deals with a specific system, taxonomic group, and geographic region and uses different methods to assess the relationship between species traits and the environment. As a consequence, we do not know how generalizable apparent relationships are, nor how they vary across ecosystems, realms, and taxonomic groups. In addition, while there is an emerging synthesis about the role of traits for terrestrial plant communities 13,14 , we know much less about other groups and ecosystem types.To address these gaps, we introduce the CESTES database -a global database for metaCommunity Ecology: Species, Traits, Environment and Space. This database assembles 80 datasets from studies that analysed empirical multivariate trait-environment relationships between 1996 (the first...

Chironomid larvae were collected and abiotic variables measured at monthly intervals at 21 sampling stations in two lagoons (Guaraná and Patos) and two tributaries (Baía and Ivinheima) of the Upper Paraná River floodplain. The genera Procladius, Chironomus, Goeldichironomus, and Polypedilum were dominant in the lagoons and in the Baía River, while Cryptochironomus and Lopescladius were more dominant in the Ivinheima River. The similarity in the generic composition of the chironomids of the lagoons and the Baía River is probably due to the fact that this river presents hydrodynamic characteristics similar to those of the lagoons. The results obtained suggest that the hydrodynamics of these environments are the main factor determining spatial variation in the chironomid fauna. This is intuitively clear, as this factor itself determines sediment type, quantity of organic matter and presence or absence of aquatic macrophytes. However, on a seasonal scale, the flood pulse seems to be the main controlling factor of the temporal variation in densities and dominance of chironomid larvae. Given that this factor has a large influence on the temporal dynamics of several limnological variables, this is again a logical correlation. Our results suggest a strong relationship between the variations in the chironomid community and fluctuations in limnological characteristics.Key words: Chironomidae, zoobenthos, floodplain, spatial and temporal variation. RESUMOVariação espacial e temporal da densidade de larvas de quironomídeos (Diptera) em duas lagoas e dois tributários da planície de inundação do alto rio Paraná, Brasil Foram coletadas larvas de quironomídeos e medidas as variáveis abióticas, mensalmente, em 21 pontos distribuídos em duas lagoas (Guaraná e Patos) e dois tributários (Baía e Ivinheima) da planície de inundação do alto rio Paraná. Os gêneros Procladius, Chironomus, Goeldichironomus e Polypedilum foram dominantes nas lagoas e no rio Baía, enquanto Cryptochironomus e Lopescladius dominaram no rio Ivinheima. Essa semelhança na composição genérica de quironomídeos nas lagoas e no rio Baía provavelmente se deve ao fato de esse rio apresentar características hidrodinâmicas mais similares às das lagoas. Os resultados obtidos sugerem que a hidrodinâmica desses ambientes é o principal fator determinante na variação espacial da fauna de quironomídeos. Obviamente, esse fator determina o tipo de sedimento, teor de matéria orgânica e presença ou ausência de macrófitas aquáticas. No entanto, sazonalmente, o pulso de inundação parece ser o principal fator controlador da variação temporal da densidade e da dominância das larvas de quironomídeos. Tendo em vista que esse fator tem grande influência na dinâmica temporal das variáveis limnológicas, isso é novamente uma correlação lógica. Os resultados sugerem forte relação entre as variações na comunidade de quironomídeos e as flutuações nas características limnológicas.Palavras-chave: Chironomidae, zoobentos, planície, variação espacial e temporal.

Non-native aquatic macrophytes have invaded different types of ecosystems all over the world. The exotic submersed macrophyte Hydrilla verticillata recently invaded the Paraná basin, Brazil, being recorded by the first time in the natural habitats of this river in 2005. We investigated the effects of this species on ostracod assemblages and compared the abundance, richness, and Shannon-Wiener diversity of ostracod assemblages that colonize the invading species with those that colonize Egeria najas, a native submersed species with similar architecture and physical complexity. Fragments of these two species were left for 28 days in tanks to root and grow and then they were transferred to a floodplain lake where they remained in pairs (one plant of each species; N = 7) during 30 days for colonization by ostracods. A detrented correspondence analysis was used to summarize ostracod assemblage composition. Although there were no significant differences in ostracod abundance, richness and Shannon diversity when analyzed separately, cumulative curves, which permit to eliminate effects of abundance on richness, indicated a significantly higher number of ostracod species on H. verticillata. Assemblage composition was significantly different between both plant species, as shown by the first DCA axis. Our results show that H. verticillata might provide favorable habitats for native ostracod assemblages.

Aim Evaluating how groups of organisms vary in dispersal capability and how environmental, spatial and temporal signals vary across multiple scales is critical to elucidating metacommunity theory. We examined whether the relative contributions of environmental, spatial and hydrological factors have different effects on organismal groups with different dispersal abilities at three spatial scales, and how this knowledge contributes to our understanding of metacommunity dynamics. Location Four major Brazilian floodplains, with the largest distance among them of 2,300 Km. Taxon 10 aquatic organismal groups, ranging from bacterioplankton to fish. Methods We sampled lakes connected to the main river in the low‐ and high‐water periods of each floodplain between 2011 and 2012. Different biological groups were analysed across three hierarchical spatial scales (fine, intermediate and subcontinental) within and between floodplain systems. We applied a series of partial redundancy analyses to estimate the relative contributions of environmental factors, spatial factors and hydrological period for each biological group. Results At the fine spatial scale, predominantly environmental factors and hydrological period structure metacommunities, although less so for microorganisms than for micro‐invertebrates and macro‐organisms. The relative importance of environmental factors increased at the intermediate spatial scale. At the subcontinental scale, the relative importance of spatial factors increased for all biological groups, but environmental factors remained the primary regulators of microorganisms even at the largest scale. Main conclusions This study design allowed us to make more robust inferences about the mechanisms responsible for regulating community structure of distinct biological groups at different spatial scales. Our results suggest that biological groups displaying distinct body size likely determine the spatial extent at which environmental, spatial and hydrological processes prevail as the primary regulators of community structure. These findings are important in guiding the conservation and management of floodplain biodiversity because these systems are naturally highly heterogeneous in space and time.