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Wetlands have been declining worldwide, with an estimated 64���71% loss over the last century. Climate change is increasing pressure on wetlands, affecting their hydrology, and Mediterranean temporary ponds could be particularly vulnerable to these changes. We studied the expected changes in hydrology and plant community according to climatic change scenarios in 18 temporary ponds distributed in 6 areas along a latitudinal and climatic gradient in Morocco (750 km; 4�� latitudinal gradient). Richness of pond species was significantly correlated with water level and pond hydroperiod and showed a strong decline from north to south along with increased water stress. Using the Mar-O-Sel software (mar-o-sel.net), we simulated the future evolution of water balance and wetland hydroperiod (duration and frequency of flooding) in these ponds for mid- and late-21st century. Climate projections were estimated based on 2 Representative Concentration Pathway (RCP) scenarios assuming a stabilization (RCP4.5) or increase (RCP8.5) in greenhouse gas emissions. The mean water deficit of the ponds currently ranges between ���1380 and ���1812 mm/yr and would increase by 16���67% in 2100 under the RCP8.5 scenarios. Pond richness is expected to decrease by 8���15 species in 2100, depending on area, as a result of shorter projected hydroperiods. Severity of change was not related to location of the ponds along the latitudinal (aridity) gradient, but rather to the interaction between the size of their catchment area and the thickness of the permeable soil layer.

This article presents information on the distribution and ecology of Callitriche species in Morocco, based on field survey, literature review, and examination of herbarium specimens. Taxa reported erroneously from the country are discussed and new information is presented on the morphology of C. mathezii and C. truncata subsp. truncata.

Unravelling patterns and mechanisms of biogeographical transitions is crucial if we are to understand compositional gradientsat large spatial extents, but no studies have thus far examined breakpoints in community composition of freshwater plants acrosscontinents. Using a dataset of almost 500 observations of lake plant community composition from six continents, we examined,for the first time, if such breakpoints in geographical space exist for freshwater plants and how well a suite of ecological factors(including climatic and local environmental variables) can explain transitions in community composition from the subtropicsto the poles. Our combination of multivariate regression tree (MRT) analysis and k-means partitioning suggests that the mostabrupt breakpoint exists between temperate to boreal regions on the one hand and freshwater plant communities harbouringmainly subtropical or Mediterranean assemblages on the other. The spatially structured variation in current climatic conditionsis the most likely candidate for controlling these latitudinal patterns, although one cannot rule out joint effects of eco-evolutionary constraints in the harsher high-latitude environments and post-glacial migration lags after Pleistocene Ice Ages. Overall, ourstudy supports the foundations of global regionalisation for freshwater plants and anticipates further biogeographical researchon freshwater plant communities once datasets have been harmonised for conducting large-scale spatial analyses.

Limonium mucronatum (L.f.) Chaz. (Plumbaginaceae), a strict endemic of Morocco, has a restricted range in the littoral zone between Rabat and Tan Tan (Draa valley). This coastal region at the junction of Mediterranean, Canary and Saharan influences is of considerable biogeographical interest. However, little information exists on L. mucronatum communities and its relationship with bioclimatology or chromosome polymorphisms, which may have an impact in the context of plant conservation. In this study, we analysed L. mucronatum communities and performed a cytometric and karyological characterization of this rare species. Results showed two plant communities associated with this species related to a latitudinal and bioclimatic gradient along the surveyed region. Our study provided for the first time new data regarding nuclear DNA amount and about the numbers, positions and organization of 45S rDNA loci in L. mucronatum. Remarkably, cytogenetic analyses revealed homogeneous ploidy across all studied populations with all individuals with 2n¼12 chromosomes. The results obtained are discussed in the context of the originality of flora and the threats to L. mucronatum communities, and in the perspective of a conservation strategy for this endemic species info:eu-repo/semantics/publishedVersion

The ecological niche defines the favorable range of a species in a multidimensional space of ecological factors that determine the presence and function of individuals. This fundamental concept in ecology is widely used to understand plant species coexistence and segregation. In this study we test for ecological differentiation among six annual Lythrum species that are characteristic of temporary pools in the South of France, where they either coexist or occur separately. We first analysed the co-occurrence of species at two different geographical scales: cluster analyses of species presence in 10 km grid cells and coexistence in 0.25m2 quadrats within populations of each species. Second, for three to nine populations of each species, we quantified a range of biotic and abiotic parameters using point contacts and soil measurements in three 0.25m2 quadrats per population. We performed PCA on all variables, and analysed each variable separately to compare the ecological niche features of the six species. A phenological index was assessed for the plant community of each site. We detected highly localised niche differentiation in terms of soil pH (all species) and for a range of variables among pairs of species. The six species also showed marked differences in flowering period relative to the mean and variability of flowering time in their local community. These fine-scaled niche differences are associated with phylogenetic distances among species and may contribute to species’ coexistence. These results are integrated in a conservation management plan for the habitat of the rarest species in this group.

International audience; Coastal lagoons have been recognised as a priority habitat for conservation and have benefited from several conservation plans. Under the Mediterranean climate, some of these lagoons might dry out during summer due to drought events. We propose the term Mediterranean Temporary Lagoons (MTLs) for these ephemeral water bodies and discuss their definition and characteristics. This term emerged in France among its coastal zone managers, who now commonly use it for conservation purposes. It is used in both natural systems as well as most artificial salt ponds in abandoned saltworks. In Europe, two directives have integrated lagoons as key targets to be preserved. Nonetheless, a certain discrepancy in the different definitions of lagoons has constrained joint actions. Indeed, while institutional definitions were originally derived from the scientific concept, their legislative and managerials meanings have been gradually modified and nowadays often differ from the original concept to create difficulties in the field. In addition, while it has been recommended to consider MTLs as a coastal lagoon habitat in the European Habitat Directive, its interpretation among EU member states is unsettled. Thus, clarifying lagoon habitats' terminology is required to ensure better management, monitoring and planning, and coordinate conservation actions. We discuss the inclusion of MTLs in habitat 1150 by confronting scientific and institutional literature and propose a new framework to better delimitate lagoon habitat around the Mediterranean basin, integrating MTLs. MTLs represent a specific habitat that hosts a pool of stenoecious macrophytes of conservation interest like Althenia filiformis, Riella helicophylla or Tolypella salina.

International audience; The relevant benefits of hyperspectral sensors for water column determination and seabed features mapping compared to multispectral data, especially in coastal areas, have been demonstrated in recent studies. In this study, we used hyperspectral satellite data in the accurate mapping of the bathymetry and the composition of water habitats for inland water. Particularly, the identification of the bottom diversity for a shallow lagoon (less than 2 m in depth) was examined. Hyperspectral satellite data were simulated based on aerial hyperspectral imagery acquired above a lagoon, namely the Vaccarès lagoon (France), considering the spatial and spectral resolutions, and the signal-to-noise ratio of a satellite sensor, BIODIVERSITY, that is under study by the French space agency (CNES). Various sources of uncertainties such as inter-band calibration errors and atmospheric correction were considered to make the dataset realistic. The results were compared with a recently launched hyperspectral sensor, namely the DESIS sensor (DLR, Germany). The analysis of BIODIVERSITY-like sensor simulated data demonstrated the feasibility to satisfactorily estimate the bathymetry with a root-mean-square error of 0.28 m and a relative error of 14% between 0 and 2 m. In comparison to open coastal waters, the retrieval of bathymetry is a more challenging task for inland waters because the latter usually shows a high abundance of hydrosols (phytoplankton, SPM, and CDOM). The retrieval performance of seabed abundance was estimated through a comparison of the bottom composition with in situ data that were acquired by a recently developed imaging camera (SILIOS Technologies SA., France). Regression coefficients for the retrieval of the fractional species abundances from the theoretical inversion and measurements were obtained to be 0.77 (underwater imaging camera) and 0.80 (in situ macrophytes data), revealing the potential of the sensor characteristics. By contrast, the comparison of the in situ bathymetry and macrophyte data with the DESIS inverted data showed that depth was estimated with an RSME of 0.38 m and a relative error of 17%, and the fractional species abundance was estimated to have a regression coefficient of 0.68

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.

International audience; Seagrass decline due to a variety of stressors has been observed worldwide. In the shallow Vaccarès lagoon, Camargue, France, the dominant macrophyte species, Zostera noltei, has suffered two major declines since 1996. The first decline was well explained by salinity and turbidity variations, while the second one could not be explained by these parameters. Other stressors such as chemical contamination, eutrophication or temperature increase could be explanatory variables for this most recent decline. The aim of our study was to understand, via scientific monitoring from 2011 to 2015, the influence of chemical contamination and its possible interactions with other biological and environmental pressures, on seagrass physiology and population dynamics in the Vaccarès lagoon. Multi-contamination by organic contaminants and trace metals was detected in the water and sediments, and their concentrations often exceeded environmental standards, particularly where seagrass regression was observed. Spatial variations in biological, environmental and chemical parameters in the lagoon were investigated by co-inertia analysis, which revealed significant relationships between environmental data, more particularly between contaminants, seagrass dynamics indices and biomarkers. Seagrass dynamics indices were negatively correlated with the concentrations of some herbicides in water (2,4-MCPA and bentazon) and with trace metals in sediments (arsenic). Rhizome starch contents in winter were negatively correlated with those herbicides and with several metals (arsenic, zinc, copper) in water and/or sediments. These results suggest that environmental contamination may play a role in seagrass decline. However, complementary investigations, such as monitoring over longer periods and additional toxicity tests, are required to address the causal link between contamination and seagrass decline.

Wetlands are critically important for biodiversity and human wellbeing, but face a range of challenges. This is especially true in the Mediterranean region, where wetlands support endemic and threatened species and remain integral to human societies, but have been severely degraded in recent decades. Here, in order to raise awareness of future challenges and opportunities for Mediterranean wetlands, and to inform proactive research and management, we identified (a) 50 key issues that might affect Mediterranean wetlands between 2020 and 2050, and (b) 50 important research questions that, if answered, would have the greatest impact on the conservation of Mediterranean wetlands between 2020 and 2050. We gathered ideas through an online survey and review of recent literature. A diverse assessment panel prioritised ideas through an iterative, anonymised, Delphi-like process of scoring, voting and discussion. The prioritised issues included some that are already well known but likely to have a large impact on Mediterranean wetlands in the next 30 years (e.g. the accumulation of dams and reservoirs, plastic pollution and weak governance), and some that are currently overlooked in the context of Mediterranean wetlands (e.g. increasing desalination capacity and development of antimicrobial resistance). Questions largely focused on how best to carry out conservation interventions, or understanding the impacts of threats to inform conservation decision-making. This analysis will support research, policy and practice related to environmental conservation and sustainable development in the Mediterranean, and provides a model for similar analyses elsewhere in the world., Arcadia, WJS is funded by Arcadia.

The Andalusian International University held a workshop entitled Temporary wetlands’ future in drylands under the projected global change scenario in March 2020 in Baeza, Spain, with 26 participants from 10 countries. The workshop objectives were to promote international cooperation and scientific exchange on the conservation and protection of temporary wetlands. The participants highlighted the extreme conditions that temporary and permanent wetlands, ponds, and shallow lakes are currently facing and predicted a dismal future for these systems due to climate change. To foster a holistic view of these ecosystems, the workshop included wetland watersheds. It was concluded that the main threats are those affecting water quality and quantity as well as egg-seed banks, species population dynamics, and food webs. The inherent characteristics of waterbodies in drylands, including high resilience and resistance to harsh conditions, are already negatively impacted by direct human actions and climate change. Another threat is the time lag between scientific warnings about threats and the social and political concern leading to mitigating actions. Thus, more effective actions to protect and conserve temporary wetlands are essential. Research networks could help stimulate the necessary conservation actions, but the global recession due to the COVID-19 pandemic will pose a challenge as economies are burdened with urgent expenditure. This special issue of the journal Inland Waters is the outcome of the workshop presentations and is composed of the ensuing papers on wetlands in drylands. This work was supported by UNIA. Universidad Internacional de Andalucia [grant number: UNIA-WORKSHOP-2019]; Centro de Estudios Avanzados en Ciencias de la Tierra [grant number: CEACTIERRA-2020]. SB was supported by the PONDERFUL project (Pond ecosystems for resilient future landscapes in a changing climate) funded by European Union's Horizon 2020 research and innovation programme under grant agreement No. 869296. EJ was supported by the TUBITAK researchers program BIDEB 2232 (project 118C250). TZ was supported by the Israel Water Authority.

Seventeen European endemic plant species were considered extinct, but improved taxonomic and distribution knowledge as well as ex situ collecting activities brought them out of the extinct status. These species have now been reported into a conservation framework that may promote legal protection and in situ and ex situ conservation.

Documenting the patterns of biological diversity on Earth has always been a central challenge in macroecology and biogeography. However, for the diverse group of freshwater plants, such research program is still in its in- fancy. Here, we examined global variation in taxonomic, functional and phylogenetic beta diversity patterns of lake macrophytes using regional data from six continents. A data set of ca. 480 lake macrophyte community ob- servations, together with climatic, geographical and environmental variables, was compiled across 16 regions worldwide. We (a) built the very first phylogeny comprising most freshwater plant lineages; (b) exploited a wide array of functional traits that are important to macrophyte autoecology or that relate to lake ecosystem functioning; (c) assessed if different large-scale beta diversity patterns show a clear latitudinal gradient from the equator to the poles using null models; and (d) employed evolutionary and regression models to first identify the degree to which the studied functional traits show a phylogenetic signal, and then to estimate community- environment relationships at multiple spatial scales. Our results supported the notion that ecological niches evolved independently of phylogeny in macrophyte lineages worldwide. We also showed that taxonomic and phylogenetic beta diversity followed the typical global trend with higher diversity in the tropics. In addition, we were able to confirm that species, multi-trait and lineage compositions were first and foremost structured by climatic conditions at relatively broad spatial scales. Perhaps more importantly, we showed that large-scale processes along latitudinal and elevational gradients have left a strong footprint in the current diversity patterns and community-environment relationships in lake macrophytes. Overall, our results stress the need for an inte- grative approach to macroecology, biogeography and conservation biology, combining multiple diversity facets at different spatial scales. JGG appreciates financial support from the Spanish Ministry of Economy and Industry [project METAPONDS, grant CGL2017- 84176R], the Junta de Castilla y León [grant LE004G18] and from the Fundación Biodiversidad (Spanish Ministry for Ecological Transi- tion and Demographic Challenge). BAL was supported by National Research, Development and Innovation Fund [grant NKFIH, OTKA PD120775] and by the Bolyai János Research Scholarship of the Hun- garian Academy of Sciences. S.K. was supported by NWO Veni [grant 86312012]. Sampling of the coastal Brazilian lakes was financed by NWO [grant W84-549]; The National Geographic Society [grant 7864-5]; and CNPq [grants 480122, 490409, 311427]. We thank the SALGA team, especially Gissell Lacerot, Nestor Mazzeo, Vera Huszar, David da Motta Marques, and Erik Jeppesen for organizing and exe- cuting the SALGA field sampling campaign and Bruno Irgang† and Eduardo Alonso Paz for helping with identification. We thank Minne- sota and Wisconsin Departments of Natural Resources for collecting the macrophyte data. We are grateful to Carol Reschke for her work in combining and performing quality control for the Minnesota mac- rophyte data used in the analysis. This is contribution no. 607 of the Natural Resources Research Inst. of the Univ. of Minnesota Duluth. Provision of New Zealand macrophyte data was possible via NIWA SSIF funding. JGG appreciates financial support from the Spanish Ministry of Economy and Industry [project METAPONDS, grant CGL2017- 84176R], the Junta de Castilla y León [grant LE004G18] and from the Fundación Biodiversidad (Spanish Ministry for Ecological Transi- tion and Demographic Challenge). BAL was supported by National Research, Development and Innovation Fund [grant NKFIH, OTKA PD120775] and by the Bolyai János Research Scholarship of the Hun- garian Academy of Sciences. S.K. was supported by NWO Veni [grant 86312012]. Sampling of the coastal Brazilian lakes was financed by NWO [grant W84-549]; The National Geographic Society [grant 7864-5]; and CNPq [grants 480122, 490409, 311427]. We thank the SALGA team, especially Gissell Lacerot, Nestor Mazzeo, Vera Huszar, David da Motta Marques, and Erik Jeppesen for organizing and exe- cuting the SALGA field sampling campaign and Bruno Irgang† and Eduardo Alonso Paz for helping with identification. We thank Minne- sota and Wisconsin Departments of Natural Resources for collecting the macrophyte data. We are grateful to Carol Reschke for her work in combining and performing quality control for the Minnesota mac- rophyte data used in the analysis. This is contribution no. 607 of the Natural Resources Research Inst. of the Univ. of Minnesota Duluth. Provision of New Zealand macrophyte data was possible via NIWA SSIF funding.

International audience; Mediterranean temporary pools are threatened ecosystems that host a unique plant community, mostly composed of annual species with large and long-lived seed banks. The longevity of their seed bank, the scarcity of their habitat, the small size of their populations and the low frequency of above-ground vegetation result in a low probability of detection of these species. The discovery of new populations of such rare species are thus important for our understanding of the ecology of the temporary pool ecosystem. Lythrum thesioides M.Bieb., 1808 is a very rare annual species of temporary pools and river banks which was thought to be extinct in the South of France until 1998. Here, we review the distribution of the species and report the recent discovery of a population during a targeted search combining historical data on wetland occurrence on a particular geological substrate. We present new information on its autecology, pollen morphology and the karyotype. Only three populations are currently known worldwide for Lythrum thesioides, and only one of these has favorable management conditions. Thus, we outline new conservation perspectives in the context of a targeted search project and the conservation management of one population.

Evidence for the adaptive value of oviposition site selection in terms of increased offspring fitness is rare in predatory insects. We tested this in the damselfly Lestes macrostigma that prefers the plant Bolboschoenus maritimus. We carried out two experiments with shoots containing eggs: we flooded (1) some shoots of the same type (i.e. combination of species and desiccation state) at different dates and (2) different shoot types at the same date. Earlier flooding increased hatching success. Because B. maritimus grows in deeper parts of temporary ponds, it is flooded before other plants after the drought season, suggesting that adult oviposition site selection is driven by lower egg desiccation risk. Independently of flooding date, hatching success was higher and larvae hatched earlier when eggs were laid in B. maritimus. Faster embryonic development enhances chances to complete larval development before pond desiccation and reduces costs associated with time stress. Offspring higher fitness was more constant between shoots of B. maritimus compared to the other types of shoot, suggesting that laying eggs in one shoot of this plant leads offspring to high fitness more surely. Our results indicate that adults choose oviposition plants maximizing offspring fitness (higher hatching success and faster embryonic development).

International audience; Characeae are macroscopic green algae present in the Maghreb (Morocco, Algeria, Tunisia) that are known since the 19th century works of Desfontaines (1800) and Braun (1868). Feldmann (1946) published the first regional synthesis, and this study provides a new Maghreb-wide synthesis of all collections made since 1784 (570 observations distributed over 464 sites). Each of the 31 reported species is described in detail with its diagnostic features, ecology and distribution in the three Maghrebian countries. Distribution maps distinguish between the three collection periods: 1780–1939, 1940–1979, and 1980–2016. An illustrated key is provided to help botanists working in the Maghreb to identify the taxa. From a biogeographical perspective, the Characean flora of the Maghreb is dominated by elements originating from northern (European) countries (61.3%) that include regionally very rare species such as Chara strigosa and C. tomentosa. The Mediterranean-Atlantic element is also well represented (32.3%), with some Mediterranean endemics (Chara imperfecta, C. oedophylla, C. vulgaris var. gymnophylla). Finally, two taxa that have an affinity for tropical conditions (Chara zeylanica and Lamprothamnium succinctum) extend to the southern Sahara. In North Africa, 14 species (7 Chara, 2 Lamprothamnium, 4 Nitella and 1 Sphaerochara) are threatened and raise issues about their conservation; three of these are particularly endangered: Chara imperfecta, C. oedophylla and Lamprothamnium papulosum.

International audience; Background: Temporary ponds, an abundant habitat in the Maghreb region and notably in Morocco, have a high conservation value. However, they are mainly known from the north of the country.Aims: The aim of this work was to characterise the vegetation of Moroccan temporary ponds along a combined gradient of latitude and anthropogenic pressure.Methods: Eighty-five ponds distributed along a north–south gradient of 750 km were sampled. For each pond, all vegetation was surveyed (flooded and dry parts) and the local abiotic characteristics were measured during two successive hydrological cycles. The prevailing anthropogenic pressures were also identified and were attributed an impact score.Results: Eighty-one characteristic pond species (including 17 rare species) were recorded, with several new distribution data in the southern part of the latitudinal gradient. Plant communities were related to climatic and anthropogenic factors, but mostly to local factors, such as maximum water depth and soil pH. The northern ponds (wettest macroclimate) were rich in characteristic species and rare species, while the southern (driest macroclimate) ponds were more species poor.Conclusions: In addition to the direct impact of increasing human activity, a further reduction of the floristic richness of temporary ponds is expected due to climatic changes. This is particularly the case for characteristic species which have a high conservation value.

Wetlands in countries around the Mediterranean Sea have provided ecosystem services to its population for more than 6000 years (Nile, Mesopotamian civilizations). Rising population numbers, consumption patterns that increase demands on resources, and reduced water renewal rates have been putting existing social-ecological interactions under considerable stress. This renders both ecosystems and people more vulnerable to naturally existing hazards, because it increases the likelihood that a hazard will occur and increases the potential damage that may be caused. The general trends of declining biodiversity and reducing water availability, as well as an increase in demand for ecosystem services, make Mediterranean wetlands and the people that depend on them less resilient and increasingly exposed and vulnerable to physical and economical hazards that naturally occur in the Mediterranean basin. This fragility is likely to only further increase as these trends have yet to be countered and the frequency and intensity of hazards are likely to increase under the influence of climate change and other anthropogenic pressures. Conservation and sustainable use of Mediterranean wetlands are therefore a serious challenge, but of increasing urgency if we are sincerely concerned about human well-being in the Mediterranean basin.

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.

The metabolic balance of the open waters supporting submerged macrophytes of the Doñana marsh (SW Spain) was investigated in spring, when community production is highest. The marsh community (benthic + pelagic) was net autotrophic with net community production rates averaging 0.61 g C m -2 d-1, and gross production rates exceeding community respiration rates by, on average, 43%. Net community production increased greatly with increasing irradiance, with the threshold irradiance for communities to become net autotrophic ranging from 42 to 255 μE m -2 s-1, with net heterotrophic at lower irradiance. Examination of the contributions of the benthic and the pelagic compartments showed the pelagic compartment to be strongly heterotrophic (average P/R ratio Combining double low line 0.27), indicating that the metabolism of the pelagic compartment is highly subsidised by excess organic carbon produced in the strongly autotrophic benthic compartment (average P/R Combining double low line 1.58). © 2011 Author(s)., The metabolic balance of the open waters supporting submerged macrophytes of the Donana marsh (SW ˜ Spain) was investigated in spring, when community production is highest. The marsh community (benthic + pelagic) was net autotrophic with net community production rates averaging 0.61 g C m−2 d −1 , and gross production rates exceeding community respiration rates by, on average, 43%. Net community production increased greatly with increasing irradiance, with the threshold irradiance for communities to become net autotrophic ranging from 42 to 255 µE m−2 s −1 , with net heterotrophic at lower irradiance. Examination of the contributions of the benthic and the pelagic compartments showed the pelagic compartment to be strongly heterotrophic (average P/R ratio = 0.27), indicating that the metabolism of the pelagic compartment is highly subsidised by excess organic carbon produced in the strongly autotrophic benthic compartment (average P/R = 1.58).

Este artículo contiene 16 páginas, 3 tablas, 2 figuras., We studied community–environment relationships of lake macrophytes at two metacommunity scales using data from 16 regions across the world. More specifically, we examined (a) whether the lake macrophyte communities respond similar to key local environmental factors, major climate variables and lake spatial locations in each of the regions (i.e., within-region approach) and (b) how well can explained variability in the community–environment relationships across multiple lake macrophyte metacommunities be accounted for by elevation range, spatial extent, latitude, longitude, and age of the oldest lake within each metacommunity (i.e., across-region approach). In the within-region approach, we employed partial redundancy analyses together with variation partitioning to investigate the relative importance of local variables, climate variables, and spatial location on lake macrophytes among the study regions. In the across-region approach, we used adjusted R2 values of the variation partitioning to model the community–environment relationships across multiple metacommunities using linear regression and commonality analysis. We found that niche filtering related to local lake-level environmental conditions was the dominant force structuring macrophytes within metacommunities. However, our results also revealed that elevation range associated with climate (increasing temperature amplitude affecting macrophytes) and spatial location (likely due to dispersal limitation) was important for macrophytes based on the findings of the across-metacommunities analysis. These findings suggest that different determinants influence macrophyte metacommunities within different regions, thus showing context dependency. Moreover, our study emphasized that the use of a single metacommunity scale gives incomplete information on the environmental features explaining variation in macrophyte communities., Open access funding provided by University of Oulu including Oulu University Hospital. JA appreciates financial support from the Ella and Georg Ehrnrooth Foundation. BAL was supported by National Research, Development and Innovation Office—NKFIH, OTKA PD120775 Grant and by the Bolyai János Research Scholarship of the Hungarian Academy of Sciences. S.K. was supported by NWO Veni grant 86312012. Sampling of the coastal Brazilian lakes was financed by NWO grant W84-549; The National Geographic Society grant 7864-5; and CNPq grants 480122, 490409, 311427.

Given that people are an inseparable part of their environment through their dependence on ecosystems and the services they provide, it is essential to understand the human influences that impact the environment and in turn determine the effects they will have on the existing ecosystem services. This relationship was explored by coupling a habitat vulnerability study with an ecosystem service perception evaluation. A biological survey and a socio-economic study were implemented in western Morocco (Benslimane Province) to identify the vulnerability of different temporary pools and to determine the perceived ecosystem services obtained by local stakeholders. A total of 101 temporary pools were studied and in person interviews were conducted with 110 randomly selected households. For each pool, vulnerability to various land uses, pressures and threats were analyzed. Temporary pools located in forested areas were under less threat than those located in agricultural lands. The nuisances associated with temporary pools were indicated by local stakeholders, increasing the pools’ vulnerability. Provisioning and cultural ecosystem services were also perceived, increasing acceptance for conservation measures. The results of this study highlight the need to account for natural science and social sciences to inform future management. This methodology can further be tested and applied in other fragile ecosystems to better target conservation strategies.

EU countries are required to perform an assessment of all freshwater habitats larger than 50 ha by 2015 to meet the requirements set by the Water Framework Directive (2000). To achieve this, an array of indicators and multimetric indices has been developed to monitor European waters. In general, these indicators are developed for large water bodies, while they are still largely lacking for smaller wetlands. This is in contrast with the conservation value, valuable ecosystem services and the often unique biodiversity of these systems, and the fact that like large (>50 ha) wetlands they are also covered by the Ramsar Convention. In (semi) arid regions, such as the Mediterranean basin, small water bodies are often of a temporary nature, are abundant and provide an important source of water for the local people, their livestock and agriculture. The quantity and quality of temporary wetlands are, however, decreasing at an alarming rate worldwide. Although some monitoring techniques were recently proposed, there is still an urgent need for a consistent policy and a user friendly set of monitoring tools for temporary wetlands that can be applied in different regions. In the following review, we present a whole range of indicators used to monitor different types of freshwater habitats, and discuss how some of these methods could be applied to temporary wetlands. Finally, we formulate some recommendations for temporary wetland monitoring and conservation.

Este artículo contiene 14 páginas, 3 tablas, 3 figuras., Aim: We studied global variation in beta diversity patterns of lake macrophytes using regional data from across the world. Specifically, we examined (1) how beta diversity of aquatic macrophytes is partitioned between species turnover and nestedness within each study region, and (2) which environmental characteristics structure variation in these beta diversity components. Location: Global. Methods: We used presence–absence data for aquatic macrophytes from 21 regions distributed around the world. We calculated pairwise-site and multiple-site beta diversity among lakes within each region using Sørensen dissimilarity index and partitioned it into turnover and nestedness coefficients. Beta regression was used to correlate the diversity coefficients with regional environmental characteristics. Results Aquatic macrophytes showed different levels of beta diversity within each of the 21 study regions, with species turnover typically accounting for the majority of beta diversity, especially in high-diversity regions. However, nestedness contributed 30–50% of total variation in macrophyte beta diversity in low-diversity regions. The most important environmental factor explaining the three beta diversity coefficients (total, species turnover and nestedness) was elevation range, followed by relative areal extent of freshwater, latitude and water alkalinity range. Main conclusions: Our findings show that global patterns in beta diversity of lake macrophytes are caused by species turnover rather than by nestedness. These patterns in beta diversity were driven by natural environmental heterogeneity, notably variability in elevation range (also related to temperature variation) among regions. In addition, a greater range in alkalinity within a region, likely amplified by human activities, was also correlated with increased macrophyte beta diversity. These findings suggest that efforts to conserve aquatic macrophyte diversity should primarily focus on regions with large numbers of lakes that exhibit broad environmental gradients., The gathering of the Finnish data was partly supported by Biological Monitoring of Finnish Freshwaters under diffuse loading -project (XPR3304) financed by Ministry of Agriculture and Forestry and partly by national surveillance monitoring programs of lakes. S.H. and M.M. were supported by the EU-funded MARS-project (7th EU Framework Programme, Contract No.: 603378).Swedish macrophyte data were collected within the Swedish Monitoring Program of macrophytes in lakes funded by the Swedish Agency for Marine and Water Management. S.K. was supported by NWO Veni grant 86312012. Macrophyte data from Brazilian Amazon were collected within a limnological monitoring program funded by Vale S.A. The vast majority of macrophyte data from Polish lakes were collected within the State Environmental Monitoring Programme and were provided by the Inspection for Environmental Protection. Macrophyte data for British lakes were collated by the Joint Nature Conservation Committee from surveys resourced by the national conservation agencies. Swiss macrophytes data were collected during a study financially supported by the Swiss Federal Office for the Environment. Wisconsin data collection was funded by the Wisconsin Department of Natural Resources and supported by the Wisconsin Cooperative Fishery Research Unit. The Norwegian macrophyte data were collected within the European Union project ‘LAKES – Long distance dispersal of Aquatic Key Species’, contract no. env4-ct-97-0585.

The mute swan Cygnus olor Gmelin and the greater flamingo Phoenicopterus roseus Pallas potentially affect plants, directly through grazing and indirectly through mechanical disturbance during their foraging activities. We studied in a field exclosure experiment, from May 2010 to July 2011, their respective impact on macrophytes in two Mediterranean lagoons (Camargue, South of France) with different plant communities. In one lagoon, greater flamingo negatively affected Ruppia cirrhosa Petagna cover from June to July, and dry biomass in July. In the other lagoon, greater flamingo and mute swan had a detrimental effect on Zostera noltii Hornemann cover at the beginning of the growing season (April). They also reduced Chaetomorpha sp. cover from April to July and dry biomass in July. Combined activities of waterbirds decreased the dominance of Chaetomorpha sp. bed, thus favouring later (July) Z. noltii cover and partially dry biomass in areas available for greater flamingo and mute swan. However, the impact of waterbirds was not entirely beneficial for Z. noltii , as its abundance during July was indeed higher in ungrazed areas with low Chaetomorpha sp. abundance in previous months. The combined effect of waterbirds on Z. noltii is thus dual, mainly favouring its development by reducing competing macroalgae but conversely mitigating it through direct impact at both ends of the growing season. Depending on the ecological context, waterbirds can thus affect in two opposite ways the growth of plant species such as Z. noltii or R. cirrhosa which are of importance with regard to conservation. Large waterbird species can be considered as ecosystem engineers in Mediterranean wetlands.

In a large-scale and long-term outdoor mesocosm (400-liter) experiment, we studied the interacting effects of salinity and disturbance (hydrological) regime on the active and dormant crustacean communities of Mediterranean temporary wetlands (Camargue, southern France). Sixty-four mesocosms, inoculated with a regional species pool (mixed dormant egg banks), were exposed to a full factorial treatment combination of four salinity levels and four disturbance regimes during three consecutive years. Both in the active and dormant community component, considerable shifts in community composition occurred because of direct and probably also second-order effects of the treatments. All large branchiopod species had low long-term salinity tolerances and showed species-specific preferences for disturbance regimes according to their life cycle strategy. The highest salinity (5) was not limiting for cladocerans and ostracods, which thrived in the absence of the competitively stronger, predatory, and bioturbating large branchiopods. Copepods were negatively associated with salinity and coped better with the imposed biotic pressure. Zooplankton diversity and density peaked in intermediate- disturbance regimes, probably because only specialized species survived the high-disturbance regimes, whereas at low-disturbance frequencies high densities of predatory Triops controlled zooplankton communities. Although crustacean dormant egg banks can temporarily buffer against unfavorable conditions, persisting bad conditions may lead to their exhaustion within 4 to 10 yr. Predicted aridification (leading to more intense disturbance regimes) may result in the loss of late successional species (chydorids and ostracods), whereas salinization may wipe out sensitive freshwater species such as large branchiopods.

Although Mediterranean temporary pools are of great value for conservation, they are in rapid decline under the impact of various forms of anthropogenic pressure. Their disappearance from the landscape may result in a weakening of the biological connections between pools due to increasing isolation and the impoverishment of their communities. In Western Morocco (province of Benslimane), temporary pools have undergone severe regression over the past decades. The quantification of these losses and the impact on the richness of plant communities remain, however, unstudied. Since this is of vital importance for the conservation of the biodiversity of these habitats, a study has been undertaken associating (1) an assessment of the pool losses (both in density and surface area) between 1955 and 2001 using remote sensing, (2) surveys of vegetation and water depth (in 2006) in 48 pools, and (3) an assessment of the density and surface area of pools occurring within a 3 km radius around each of the sampled pools. The results show a loss of 23% in number and 61% in surface area of pools in the province over a period of 47 years. This decline, promoted by their small size and shallowness, is probably related to socio-economic changes (intensification of agricultural practices and population growth). The richness in characteristic and rare species of the pools was related to both local (water depth) and regional features (land use, pool density and total water surface area in the surrounding landscape). The significant impact of the current density of pools and their total surface area on the conservation value of the studied pools suggests a weakening of the metacommunity dynamics between pools. Given the rapid socio-economic changes in the province and the current rate of pool disappearance (0.5% per year) we predict a continuing reduction in pool density with a high risk of the widespread loss of their unique flora in the long term.

Mediterranean temporary pools are frequently visited habitats where domestic livestock and wild herbivores generate numerous physical soil disturbances. Using two sizes of experimental plots (large, 1.20 m × 1.20 m; small, 0.3 m × 0.3 m), the effects of soil disturbances on vegetation dynamics and the vertical distribution of seeds were studied in one Moroccan temporary pool. Results show a very rapid regeneration of temporary wetland vegetation in disturbed plots. The speed of regeneration depends on the size of disturbance and hydrology. There was an almost complete return of vegetation to the reference state in the small disturbed plots by the end of the 1st year. This fast restoration was mainly due to seed banks, which play a key role in the resilience of pools to the different sizes of disturbances frequently generated by herbivores, but also to lateral colonization by perennials.

Bellis prostrata Pomel (Asteraceae), una nueva especie para Marruecos Key words.North Africa, endemic species, conservation, temporary wetland. Palabras clave. Norte de África, especie endémica, conservación, humedales temporales.

Morocco is rich in temporary pools which harbour numerous rare plant species. Long-term conservation of such threatened plant communities should be based on the understanding of their past dynamics. Despite conditions unfavourable to pollen preservation, surface sediments of acidic temporary pools are shown to contain pollen assemblages likely to allow vegetation reconstruction. Knowledge of the modern relationships between pollen and vegetation is, however, necessary for interpreting fossil data in terms of past vegetation. Surface pollen assemblages and floristic surveys of a temporary pool in Benslimane forest, western Morocco, are compared in order to evaluate the pollen record of the local hydrophytic vegetation. Floristic surveys were carried out for 12 years (1996–2008) along two crossing permanent transects. A set of 21 surface-sediment samples, taken along the same transects in 2007, were analysed for pollen. The spatial relationships between vegetation and pollen assemblages are explored by means of multivariate analyses, statistical tests and linear regressions. The calculation of representation indices moreover allows proposing quantitative ways for pollen-based plant-abundance reconstruction. Results reveal that the vegetation structure along the hydrological gradient is well recorded in the pollen assemblages, with: (1) a marginal zone characterised by terrestrial taxa and rare amphibious taxa (Elatine, Pilularia), (2) an intermediate zone of amphibious taxa (Alisma-type, Illecebrum/Paronychia, Isoetes velata-type), and (3) a central zone of aquatics (Myriophyllum alterniflorum, Ranunculus-type). The best correlation between the pollen record and total pool vegetation was found in the centre of the pool, which supports the reliability of the study of a single core from the centre of the pool for the reconstruction of the past dynamics of the local hydrophytic vegetation. Both the qualitative ‘community’ approach (representation indices and indicator pollen taxa) and the quantitative ‘taxa’ approach (correction factors) suggest that reconstructions of past populations can be achieved from a few taxa, namely Isoetes velata-type, Myriophyllum alterniflorum and Ranunculus-type. For these taxa, regression parameters (slope and y-intercept) have been calculated between pollen percentages and plant percentages in present vegetation, and between pollen influxes and plant abundances, respectively. These parameters can be extended to interpret fossil data from other temporary pools within the same region to reconstruct their relative and absolute past plant abundances.

The impact of grazing on the vegetation of Moroccan temporary pools has been studied at 2 scales: regional (inter-pools) and local (intra-pools). Half of the 16 forest pools studied is located in a reserve and ungrazed. The other half, located within public forest, is grazed. Vegetation relevés coupled to water-depths measurements were carried out in each pool. The results showed a significant effect of grazing on both scales of analysis. This effect was found in the species composition of the vegetation, which differed between the 2 types of pools, and in the lower species richness and abundance of plant species in the grazed pools. These differences are interpreted as resulting from the selection by herbivores and the differential tolerance of species to disturbance. These impacts are likely to expose certain species to local extinction by reducing their populations.

Many freshwater invertebrates rely on vectors for their passive dispersal. A wide array of vectors has already been investigated, but dispersal mediated by aquatic mammals remains largely unknown. Since nutria (Myocastor coypus Molina, 1782) live in a variety of aquatic habitats and frequently move around between these water bodies, they have the opportunity to transport hitch-hiking aquatic invertebrates along with them. We investigated the presence of aquatic invertebrates in their fur to evaluate this hypothesis. This study demonstrates the feasibility of ectozoochory in a broad array of freshwater invertebrates by nutria on a local scale. More than 800 invertebrates of 14 different taxa were retrieved from the fur of 10 nutria specimens, including cladocerans, copepods, ostracods, rotifers, bryozoans, dipterans, nematodes, annelids and collembolans. Many of these freshwater invertebrates could survive at least 30 min in the moist fur of nutria. Therefore, we can state that besides modifying aquatic habitats physically by clearing vegetation or digging, nutria may also alter invertebrate communities by introducing new species or genotypes.

In a large-scale outdoor mesocosm experiment we studied the effects of salinity on successional patterns, diversity, and relative abundances of Camargue (southern France) temporary pool crustaceans. Eighty mesocosms were inoculated with a mixed resting egg bank and exposed to four different salinity treatments (0.5, 1.0, 2.5, and 5.0 g L21) for a period of 7 months. Salinity significantly altered crustacean communities hatching from the resting egg bank through a number of direct and indirect effects. Salinity had a significant negative effect on the establishment of large branchiopods and copepods. Both richness and density of cladocerans, especially chydorids, were positively related to salinity, possibly due to the absence of biotic interactions with large branchiopods at the highest salinity values. We hypothesize that the salinity-mediated presence of the large branchiopod keystone group can shift the whole wetland regime from a zooplankton-rich clear-water state to a zooplankton-poor turbid state. Crustacean succession was significantly altered by salinity, by slowing down development rates, population growth or maturation rates of some species. This suggests that in addition to salinity changes, any alteration of wetland hydroperiod (e.g., through aridification or inappropriate water management) could have a synergistic effect on community structure and diversity of invertebrate communities, including some keystone species.

1. Several human activities, such as actions for nature conservation, research and recreational activities, are closely associated with inland aquatic habitats that are usually considered as isolated island habitats. In this study, the possibility of unintentional dispersal of aquatic invertebrates among water bodies via footwear and motor vehicles was investigated. 2. Mud samples collected from boots and from the tyres and wheel cases of cars used for field work by biologists (Camargue, Southern France) were hatched under laboratory conditions and also checked for the presence of unhatched propagules. A large number of organisms hatched and invertebrate propagules from a wide range of taxa were encountered (including Artemia, freshwater large branchiopods, Cladocera, Ostracoda, Rotifera, Turbellaria, Nematoda, etc.). The results also demonstrated that different research groups tend to transport the aquatic invertebrates typical for their respective study systems. 3. Human dispersal of aquatic invertebrates has been studied mainly on large continental scales, such as in the case of transoceanic transport via ballast water in ships. This study provides evidence that dispersal via footwear and motor vehicles may result in frequent dispersal of aquatic invertebrates on a local scale, and we presume also occasionally over longer distances. Given the rapid spread of invasive zooplankton species (e. g. Artemia franciscana encountered in this study), we promote caution and recommend cleaning before transport of any equipment which comes in contact with water or aquatic sediment. Copyright (C) 2010 John Wiley & Sons, Ltd.

Disturbances are key factors in the dynamics and species richness of plant communities. They create regeneration niches allowing the growth of new individuals in patches submitted to lower intensity of competition. In Mediterranean temporary pools, the intense summer drought constitutes for communities a large-scale disturbance whose intensity varies along the topographical and hydrological gradient between the centre and the edges. In this context, the importance of small-scale disturbance, such as those created by trampling and rooting herbivores in temporary pools, is poorly known. The recolonisation of small bare patches of a woodland temporary pool in western Morocco was studied experimentally in the field. The experiment was carried out using nine small control plots and nine experimental plots (sterilisation of the soil) distributed along the topographical gradient (centre, intermediate and edge zones). The area covered by plant species, and the water levels, were recorded for the plots over two successive hydrological cycles (2006/2007 and 2007/2008). The effects of natural history traits (size of seeds, presence or absence of dispersal mechanisms and annual/perennial) on the success of recolonisation of individual species were analysed. The results show that the experimental plots were rapidly recolonised. The community composition apparently was affected by the very dry conditions during the first year of the experiment, when annual species were largely absent and the clonal perennial species (Bolboschoenus maritimus and Eleocharis palustris) were dominant in the centre and intermediate zones, whilst not a single species colonised the edge zone. In the second year, less dry hydrological conditions allowed annual plants to appear in all three zones. After 2 years, the species composition of the vegetation in the experimental plots was similar to that of the unsterilised (control) plots. The abundance of plants in the centre zone was identical for experimental and control plots; in the intermediate and edge zones, the species’ abundance was lower in the experimental plots than in the control plots, suggesting an incomplete return to the reference condition (control state). Differences in abundance of species were uncorrelated with the size of seeds or to the annual/perennial nature of the plants, but were particularly dependent on the hydrological conditions, which favoured lateral colonisation by perennials (runners, rhizomes). These results show that recovery from the minor disturbances can be rapid in Mediterranean temporary pools.

Bolboschoenus maritimus, a clonal species, is locally invasive in Mediterranean temporary pools where it threatens endangered rare plant species such as Isoetes setacea. The combination of management modifications (grazing) and of the progressive accumulation of fine sediments in the pools contributed to the establishment of competitive perennial plants such as B. maritimus. The competitive advantage of B. maritimus on I. setacea has been studied in controlled conditions. The goal of this experiment was to assess the role of environmental conditions in the output of the competition between Bolboschoenus and Isoetes, notably hydrology and soil richness. For this purpose, Isoetes was cultivated alone (three individuals/pot) and with Bolboschoenus (three individuals of both species). The experiment was run with five replicates on six types of sediment (gradient of richness in sand/silt/clay) combined with three hydrological treatments (flooded, wet. and dry). The competitive advantage of Bolboschoenus was measured as the ratio of the production of Isoetes in mixture versus monoculture. The results showed that Isoetes was always outcompeted by Bolboschoenus. However, the competitive advantage of Bolboschoenus on Isoetes, was more related to hydrology than to soil richness. The competitive advantage of Bolboschoenus was very high in wet and flooded conditions and very low in dry conditions. This situation may lead to the extinction, medium-term, of the populations of I. setacea. The introduction of ovine grazing or of cut back practices in temporary pools could reduce the B. maritimus biomass and help toward the conservation of I. setacea populations.

The aim of this work was to test the hypotheses that the species composition of the vegetation of one pool in Morocco change continuously along with rainfall fluctuations, that among the vegetation can be recognized Pool species and Opportunistic species with distinct dynamics in time. We expected the Pool species to show lower inter-annual variation than the Opportunistic species. This hypothesis was tested in a 10-year study of the species composition of the vegetation along two permanent transects. The results showed high cumulative species richness (95 species) with large differences between years and a predominance of annual species (77). The proportion of Pool species during these 10 years was low (39%) when compared to opportunists (61%). In dry years the Opportunistic species were dominant and declined during wet years. The number of Pool species was correlated with the amount of rainfall. A large number of these species revealed a preference for wet years. No negative interaction between annuals/perennials and pools/non-pools species was found, suggesting that competition was not a major process during the survey. The intensity of the drought and flood stress, related to climate fluctuations, seems to be the main factors controlling the species composition of the vegetation of this unstable habitat. However, beyond the inter-annual fluctuation of the species composition of the vegetation a directional change was noticed. This directional change could result from a recovery process of the vegetation during the first years of the study after a severe flood which extirpated most of the Opportunistic species of the pool. In the last years this directional change of the species composition of the vegetation is less clear and random recruitment of the Opportunistic species from the surrounding forested habitats could contribute to explain inter-annual changes. The data collected over these 10 years led to the speculation of hypotheses on the consequences of climate change. The expected reduction of humid years and of rainfall regionally may lead to important changes in the species composition of the vegetation of the temporary pools in Morocco.

Physical soil disturbance and the hydrology of temporary pools affect the biomass, species composition and richness of plant communities. Disturbance liberates sites for the random recruitment of new individuals. The addition of seeds modifies the structure of the communities. In order to verify these hypotheses concerning the vegetation of temporary pools, an experiment was carried out using 72 soil samples collected from a pool in Western Morocco and placed in containers. Three types of laboratory treatments were applied, each combined with control treatments: soil disturbance (control/disturbed), hydrology (flooded, saturated and dry) and seed addition (sowing/no sowing). The total biomass, the annual and perennial species richness were calculated for each sample to test the effects of disturbance, hydrology and seed addition on the biomass and species richness of the various plant communities. The results show that disturbance reduces the total biomass, especially of perennials, but without significantly increasing the richness of annuals. Seed addition does not affect the total biomass and reduces total richness only in saturated soil, where biomass production is high. The most extreme stress conditions (drought and flooding) limit the abundance of species and therefore competition.

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.

Mediterranean vernal pools are threatened habitats that support a number of endangered/ rare plant and invertebrate species. Conservation management of these important habitats is limited by a lack of knowledge, especially concerning their past and present ecological dynamics. A multidisciplinary palaeoecological investigation was conducted on one of the last alkaline vernal pools of the Rhone delta (southern France). Results highlighted the value of a multidisciplinary approach based on several complementary methods, and provide direction for subsequent palaeoecological studies in temporary wetlands. Despite some degradation, fossil assemblages provide an accurate reconstruction of the past ecological dynamics of the vernal pool studied. The pool originated c. 1100 years ago from the infilling of an abandoned palaeochannel and its subsequent fragmentation. It may thus be considered as a legacy of past natural fluvial activity, which ended with the complete channelization and confinement of the River Rhone in 1869 AD. With natural processes disrupted, new pools may need to be artificially constructed in order to preserve the biological communities of alkaline vernal pools of the Rhone delta.

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.

High frequency water sampling in the wind-exposed Vaccares lagoon revealed frequent and rapid changes in suspended solid (SS) concentrations in the water column. SS concentrations, sometimes higher than 800 mg l(-1), were significantly correlated with antecedent wind conditions. Mean wind velocity during the 5-33 h before water sampling or maximal wind velocity during the previous 8.5-22 h were good predictors of SS concentrations in the water column. Underwater irradiance at canopy level was modeled (r(2) = 0.66, n = 7584) using the SS calculated from the relationship between SS and antecedent mean wind velocity and the surface irradiance data measured at the weather station close to the study site. On the other hand, we have shown that in this wind-exposed lagoon, mean underwater irradiance can not be effectively estimated using infrequent measurements of the optical properties of water.