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Spatial distribution of physical and chemical variables and macroinvertebrate composition, structure and functional aspects were investigated in five microhabitats available (Ranunculus acquatilis+ Ranunculus sardous, Spirogyra sp., Juncus effusus, and unvegetated littoral sediments and central sediments) in a temporary pond near Rome during spring 2004. The central sediments were found to differ greatly from the other substrates. They were characterized by higher nutrient contents (total P, total N), organic matter and organic C, and silt and clay in the sediments, and lower dissolved oxygen content and lower pH in the water. Species richness and densities of total macrofauna showed the lowest values in central sediments and the highest ones in submerged macrophytes (Ranunculus spp.) and emergent vegetation (Juncus effusus). Oligochaeta Tubificidae, some Nematoda (Dorylaimus spp.), and Chironomidae Tanypodinae (Procladius sp. and Psectrotanypus varius) and Chironominae (Chironomus plumosus group) characterized the central sediments, whereas Ephemeroptera and most of the Odonata and Coleoptera species were commonly found in submerged macrophyte beds. Some species of Coleoptera and Hemiptera (Hygrobia hermanni, Helochares lividus, Berosus signaticollis and Gerris maculatus) were mainly found in the algal substratum, and some Nematoda species (Tobrilus spp. and Aporcelaimellus obtusicaudatus), Oligochaeta Enchytraeidae, young larvae of Sympetrum and Diptera Ceratopogonidae in littoral sediments. Juncus effusus appeared to be mainly colonized by Chironomidae Orthocladiinae (Psectrocladius sordidellus group and Cotynoneura scutellata) and Tanytarsini (Paratanytarsus sp.). Central sediments also favoured high abundances of collector-gatherers, burrowers and drought resistant forms with passive dispersal, whereas Ranunculus spp. hosted mainly scrapers, shredders, swimmers+divers and active dispersal forms without any resistant stages to desiccation. Juncus plants were mostly colonized by collector-filterers and by organisms capable of both active dispersal and surviving desiccation. Littoral sediments and algae showed similar functional organization and intermediate features between central sediments and submerged macrophyte beds. All these results demonstrate that microhabitat characteristics play a crucial role in selecting macroinvertebrate taxa according to their environmental requirement, feeding mechanism, movement and resistance to drought. Moreover, our study confirms the role of submerged and emergent vegetation in maintaining high biodiversity and suggests that all microhabitats should be considered to provide both an exhaustive collection of species for pond management and conservation and basic insights into the functioning of pond communities. (C) 2009 Elsevier GmbH. All rights reserved

1. Ecological restoration is becoming increasingly widespread to compensate for wetland loss worldwide. However, most post-restoration studies fail to establish whether the restored wetlands replace or complement natural wetlands for communities of aquatic organisms such as macroinvertebrates. 2. During two consecutive hydroperiods (ca 6 months each), we studied the macroinvertebrate communities in 32 new temporary ponds created during a restoration 6 to 7 years previously in Doñana, SW Spain, and compared them with ten natural temporary sites nearby. We compared results for two dominant groups of active dispersers (Coleoptera and Hemiptera) and for the whole aquatic macroinvertebrate community (a mix of active and passive dispersers) to shed light on the role of dispersal constraints during ecosystem recovery. We also compared the ranks of new ponds and reference sites in nested matrices to assess whether communities in new ponds are impoverished subsets of communities in reference sites. 3. Because of their young age, newly created ponds were predicted to have less stable communities over the two study years than reference sites, and to have lower species diversity for the whole community but not for active dispersers. On the other hand, communities in new ponds were predicted to approach the taxonomic composition of reference sites as time went on. 4. New ponds differed in environmental conditions (particularly less emergent vegetation cover and lower chlorophyll concentration) from reference sites, but their invertebrate richness and diversity matched those in reference sites and invertebrate abundance was even higher. Richness and diversity increased in the second hydroperiod in new ponds, but not in reference sites. Significant differences in community composition occurred between new ponds and reference sites, but were largely explained by their environmental differences. As succession progressed within a hydroperiod, communities in new ponds were first dominated by large branchiopods, then by active dispersers such as Chironomidae and Coleoptera, then finally by halotolerant taxa such as the beetle Ochthebius viridis fallaciosus. 5. Communities in new ponds were not impoverished subsets of those in reference sites, and communities in new and reference ponds diverged towards the end of the hydroperiods. We conclude that new temporary ponds can provide diverse and complementary habitats important for maintaining macroinvertebrate diversity at the regional scale.

Summary Biological invasions have become one of the most important drivers of biodiversity loss and ecosystem change world‐wide. However, it is still unclear how invasions may interact with local abiotic stressors, which are expected to increase as global change intensifies. Furthermore, we know little about the response to biological invasions of insects, despite their disproportionate contribution to global animal biodiversity. The aim of the present work is to investigate the impact of an invasive aquatic insect on the co‐occurrence patterns of native species of insects along a salinity gradient, and determine which assembly rules are driving these patterns. First, we characterised the habitat specialisation and functional niches of each species from physiological and biological traits, respectively, and their degree of overlap. Second, we used field data to compare the co‐occurrence patterns of native and invasive species in invaded and non‐invaded areas of southern Iberia and northern Morocco. Finally, we tested if habitat filtering or niche differentiation assembly rules mediate their co‐occurrence. In non‐invaded areas, habitat filtering drives habitat segregation of species along the salinity gradient, with a lower contribution of niche differentiation. The presence of the invasive insect modifies the distribution and co‐occurrence patterns of native species. In invaded areas, niche differentiation seems to be the main mechanism to avoid competition among the invasive and native species, enabling coexistence and resource partitioning. The combined study of functional niche similarity and abiotic stressor tolerance of invasive and native species can improve our understanding of the effects of invasive species along abiotic stress gradients. This approach may increase our capacity to predict the outcomes of biological invasion in a global change context. A http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.12884/suppinfo is available for this article.