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The number and quality of temporary wetlands are declining worldwide and many of the remaining habitats are used as pastures and drinking sites for livestock. Livestock can impact wetlands through a combination of herbivory (defoliation), trampling (physical disturbance), and defecation (nutrient input), but how these influence community structure is still poorly understood. It is nonetheless generally accepted that wetland management can include some grazing, and that properly managed livestock can play a major role in wetland conservation. In Mediterranean temporary ponds, however, it is suggested that grazing might negatively affect macrophyte biodiversity within the pond basin. The impact of livestock on the characteristic freshwater fauna also remains understudied. Using an outdoor mesocosm experiment, we focused on two effects of sheep livestock (trampling and defecation) and their combination, on water quality and on faunal and floral communities from Moroccan temporary ponds. Communities from forested and agricultural sites (pond type) were also compared in a factorial design with treatments. We found that sheep‐simulated trampling and nutrient input decreased hatching invertebrate and plant richness, while lasting effects on water quality and actively colonising communities were limited. Temporary pond communities from forested and agricultural sites differed in species composition and interacted with treatments in their effects on hatching crustaceans and macrophyte species composition. Treatments had a larger effect on the species composition of forest ponds compared to agricultural ponds. These results highlight the complex effects livestock may have on aquatic communities. Water quality, taxonomic groups, and trophic levels responded negatively to trampling and waste treatments and these responses changed with pond type. With worldwide declines of seasonal wetland habitat, the effects of land use (i.e. livestock grazing) on these ecosystems and their biota are important to consider for integrated and sustainable management.

Keystone species can influence an ecosystem through a series of trophic (both direct and indirect) and non‐trophic effects. In temporary ponds, tadpole shrimps were recently identified as keystone predators, but the full extent of their ecosystem impact is still poorly known. Using a large‐scale mesocosm experiment, we quantified the impact of different Triops cancriformis densities on ecosystem properties: water quality (including chlorophyll a as measure for phytoplankton biomass) and the diversity and structure of macrophyte and zooplankton communities. Mesocosms of 400 L (1 m² surface) were lined with natural pond sediment of two study ponds differing in their natural Triops densities (Triops‐rich and Triops‐poor pond) and inundated to allow hatching from the egg bank. Afterwards, four Triops density treatments were established in the mesocosms: 0 (control), 5, 25 and 100 Triops per m². After 13 weeks, the two highest Triops densities significantly influenced the ecosystem functioning not only by triggering changes in the diversity and composition of the pond communities but also by affecting water quality through bioturbation. These results confirm that tadpole shrimp can function as ecosystem engineers in temporary ponds and could promote a shift from a clear water to a turbid state through a series of trophic and non‐trophic level effects.

Summary 1. To monitor the diversity and distribution patterns of large branchiopods and the effects of local and regional processes, 30 temporary wetlands in a nature reserve in the Camargue (southern France) were sampled and characterised during three consecutive inundations (2005–08). Additional species were added to the list for each wetland by hatching animals from the resting egg bank, after determining the optimal hatching conditions. 2. A total of five species were found, representing 28% of the species known in France and 56% of the known Camargue species. Tanymastix stagnalis, Branchipus schaefferi, Chirocephalus diaphanus (Anostraca), Triops cancriformis (Notostraca) and Imnadia yeyetta (Spinicaudata) were distributed over a total of 19 wetlands. 3. More than one species was present in 79% of the wetlands containing large branchiopods. Individual wetlands harboured on average 2.8 species, with a maximum of five coexisting species. Large branchiopod assemblages were temporally variable, differing among the three inundations with different climatological conditions. 4. The most important habitat factor influencing the distribution of large branchiopods was salinity, adversely affecting the density and survival of hatchlings. The persistence of large branchiopods in these temporary waters may be threatened by increasing salinisation driven by intensive water management and climate change.

1. Temporary aquatic habitats often are inhabited by a unique fauna and flora and contribute significantly to regional diversity. Temporary wetlands around the world are disappearing rapidly. The individual and interacting impacts of factors influencing community structure and dynamics in temporary wetlands are not always well known. 2. Camargue wetlands are mainly characterized by variable salinity and hydroperiod. The individual and combined impacts of these local factors, together with regional variables, on invertebrate communities remain unknown. We therefore characterized and sampled invertebrates in 30 temporary wetlands along salinity and hydroperiod gradients in the Camargue (Southern France) 3, 5 and 7 months after inundation. 3. Over the three sampling occasions, a total of 17 cladoceran species and 49 macroin- vertebrate taxa were identified. Hydroperiod and salinity were the most important variables explaining variation in taxonomic composition and can be considered key factors shaping the invertebrate communities in Camargue wetlands. The impact on taxon richness was significantly positive for hydroperiod but significantly negative for salinity. Regional factors had no significant effect on the structure of the studied invertebrate communities, suggesting that dispersal was not limiting and that species sorting was the most important structuring process. 4. The results of this study suggest that the combined and interacting effects of salinization and hydrological modification of Mediterranean temporary wetlands (due to water management, climate change, etc.) can result in reduced diversity in large numbers of Mediterranean wetlands and induce a considerable decline in regional diversity of aquatic invertebrates.

SUMMARY 1. Many invertebrates inhabiting insular aquatic habitats rely on external agents or vectors to disperse. Besides water connections and wind, waterfowl and amphibians are known to mediate passive dispersal of freshwater invertebrates. However, the possibility of dispersal by terrestrial mammals has been largely overlooked. 2. We investigated the potential of both external and internal zoochorous dispersal of aquatic invertebrates by the wild boar (Sus scrofa) in Mediterranean wetlands in the Camargue (France). As wild boar frequently visit wetlands for feeding and wallowing purposes, we hypothesized that they may be important passive dispersal vectors of aquatic invertebrates at a local scale. Dried mud was collected from selected ‘rubbing trees’ used by boars to dispose of parasites. Additionally, faecal pellets were collected from different locations in the wetland area. 3. Seventeen freshwater invertebrate taxa including rotifers, cladocerans, copepods and ostracods hatched from sediment obtained from ‘rubbing trees’, while invertebrates hatching from dried faeces (10 taxa) were mainly rotifers. Dispersing invertebrates were collected up to 318 m from a nearest potential dispersal source. Both abundance and richness of invertebrates significantly decreased with dispersal distance. 4. Our results demonstrate that large mammals such as wild boar can act as dispersal vectors of aquatic invertebrates at a local scale in the wetland area of the Camargue and suggest that external transport may be quantitatively more important than internal transport. As wallowing (mud bathing) is common in many terrestrial mammals, this mode of dispersal may be quite widespread.