Publications by authors named "Christophe Piscart"

Landscape heterogeneity is known as a major factor of community structure and composition. Whether this effect of the landscape extends at different scales and particularly at the relevant scale for microorganisms remained to be determined. We used the cases produced by aquatic larvae of Trichoptera, which assemble organic or mineral particles, as naturally replicated experimental systems representing structured substrates to determine the effect of landscape structuration on microbial communities.

View Article and Find Full Text PDF

Flight is a key feature of the reproduction and dispersal of emerging aquatic insects. However, morphological measurements of insect flight are mostly available for terrestrial taxa and dragonflies, while aquatic insects have been poorly investigated. We analyzed 7 flight-related morphological parameters of 32 taxa belonging to 5 orders of emerging aquatic insects (Ephemeroptera, Trichoptera, Plecoptera, Diptera, and Megaloptera) with different life history traits related to flight (dispersal strategy, voltinism, adult lifespan, and swarming behavior).

View Article and Find Full Text PDF

Mass development of macrophytes is an increasing problem in many aquatic systems worldwide. Dense mats of macrophytes can negatively affect activities like boating, fishing or hydropower production and one of the management measures often applied is mechanical removal. In this study, we analyzed the effect of mechanical macrophyte removal on phytoplankton, zooplankton, and macroinvertebrate (pelagic and benthic samples) assemblages.

View Article and Find Full Text PDF

The role of winged aquatic insects that emerge from streams and subsidize terrestrial ecosystems has been demonstrated for natural forest landscapes, but almost no information is available for intensive agricultural landscapes. This study is the first to estimate aquatic subsidies provided by flying insects that emerge from streams and land on cropland. We investigated three major groups of aquatic insects - Trichoptera, Ephemeroptera and Chironomidae (Diptera) - that emerged from 12 third-order temperate, agricultural streams.

View Article and Find Full Text PDF

Traditional morphological diagnoses of taxonomic status remain widely used while an increasing number of studies show that one morphospecies might hide cryptic diversity, i.e. lineages with unexpectedly high molecular divergence.

View Article and Find Full Text PDF

Background: The Biological Field Station of Paimpont (Station Biologique de Paimpont, SBP), owned by the University of Rennes and located in the Brocéliande Forest of Brittany (France), has been hosting student scientific research and field trips during the last 60 years. The study area of the SBP is a landscape mosaic of 17 ha composed of gorse moors, forests, prairies, ponds and creeks. Land use has evolved over time.

View Article and Find Full Text PDF

This study aimed to assess how bioturbation by freshwater benthic macroinvertebrates with different biological traits alone or in combination could modify trace elements (TE) fate between sediment and water, and if water TE concentration and animal TE content impair their body stores. Three macroinvertebrate species were exposed to TE contaminated sediment for 7 days: the omnivorous Echinogammarus berilloni (Amphipoda), the sediment feeding Tubifex tubifex (Oligochaeta) and the filter feeding Pisidium sp. (Bivalvia).

View Article and Find Full Text PDF

Intensive sampling performed in the area of Oum El Bouaghi (Northeastern Algeria) yielded a new species of the stygobiont amphipod Pseudoniphargus, P. djemoi, in wells located in the plain of Tamlouka. The new species belongs to a group that shares the display of a uropod 3 exopod extremely elongate and upcurved in the male, whereas its peduncle is only moderately elongate.

View Article and Find Full Text PDF

With an overarching goal of addressing global and regional sustainability challenges, Long Term Socio-Ecological Research Platforms (LTSER) aim to conduct place-based research, to collect and synthesize both environmental and socio-economic data, and to involve a broader stakeholder pool to set the research agenda. To date there have been few studies examining the output from LTSER platforms. In this study we enquire if the socio-ecological research from 25 self-selected LTSER platforms of the International Long-Term Ecological Research (ILTER) network has produced research products which fulfil the aims and ambitions of the paradigm shift from ecological to socio-ecological research envisaged at the turn of the century.

View Article and Find Full Text PDF

Plant litter decomposition is an essential ecosystem function that contributes to carbon and nutrient cycling in streams. Aquatic shredders, mainly macroinvertebrates, can affect this process in various ways; they consume leaf litter, breaking it down into fragments and creating suitable habitats or resources for other organisms through the production of fine particulate organic matter (FPOM). However, measures of litter-feeding traits across a wide range of aquatic macroinvertebrates are still rare.

View Article and Find Full Text PDF

Ecological criteria are needed for a comprehensive evaluation of groundwater ecosystem health by including biological components with the physical and chemical properties that are already required by European directives. Two methodological approaches to assess the ecological status of groundwater ecosystems were combined in two alluvial plains (the Ariège and Hers Rivers, southwestern France) varying in agriculture intensity (from grassland to crop rotation including maize and sunflower, and to maize monoculture). In the first approach, the composition of invertebrate assemblages (only obligate-groundwater crustaceans, i.

View Article and Find Full Text PDF

Classical species sensitivity distribution (SSD) is used to assess the threat to ecological communities posed by a contaminant and derive a safe concentration. It suffers from several well-documented weaknesses regarding its ecological realism and statistical soundness. Criticism includes that SSD does not take time-dependence of the data into account, that safe concentrations obtained from SSD might not be entirely protective of the target communities, and that there are issues of statistical representativity and of uncertainty propagation from the experimental data.

View Article and Find Full Text PDF

Temperature is one of the main abiotic factors influencing the distribution and abundance of organisms. In the Rhône River Valley, populations of the crustacean Gammarus pulex are distributed along a 5 °C thermal gradient from the North to the South of the valley. In this present work, we investigated the heat shock response of G.

View Article and Find Full Text PDF

Future climate changes and the resulting modifications in anthropogenic activities will alter the interactions between rivers and groundwater. The quantification of these hydraulic interactions is absolutely necessary for achieving sustainable water use and requires accurate analytical methodologies. This report proposes an interdisciplinary approach to the quantitative and qualitative characterization of hydraulic interactions between rivers and shallow aquifers, wherein it outlines the advantages of coupling groundwater modeling with biological markers.

View Article and Find Full Text PDF

As a consequence of global warming, it is important to characterise the potential changes occurring for some functional processes through the intra-specific study of key species. Changes in species distribution, particularly when key or engineer species are affected, should contribute to global changes in ecosystem functioning. In this study, we examined the potential consequences induced by global warming on ecosystem functioning in term of organic matter recycling.

View Article and Find Full Text PDF

In a global change context, the intensity and the frequency of drastic low flow periods or drought events will most likely increase to a substantial extent over the coming decades, leading to a modification in the abiotic characteristics of wetlands. This change in environmental parameters may induce severe shifts in plant and animal communities and the functioning of ecosystems. In this study, we experimentally estimated the effect of drought and the accumulation of ammonia (NH3 ) on the feeding activities of three generalist macroinvertebrates (i.

View Article and Find Full Text PDF

Secondary salinisation of rivers and streams is a global and growing threat that might be amplified by climate change. It can have many different causes, like irrigation, mining activity or the use of salts as de-icing agents for roads. Freshwater organisms only tolerate certain ranges of water salinity.

View Article and Find Full Text PDF

In a context of global change, increases in temperature and in ammonia concentration should strongly affect the crustaceans of wetlands. We experimentally examined, at three different seasons (i.e.

View Article and Find Full Text PDF

Salinity is a key abiotic property of inland waters; it has a major influence on biotic communities and is affected by many natural and anthropogenic processes. Salinity of inland waters tends to increase with aridity, and biota of inland waters may have evolved greater salt tolerance in more arid regions. Here we compare the sensitivity of stream macroinvertebrate species to salinity from a relatively wet region in France (Lorraine and Brittany) to that in three relatively arid regions eastern Australia (Victoria, Queensland and Tasmania), South Africa (south-east of the Eastern Cape Province) and Israel using the identical experimental method in all locations.

View Article and Find Full Text PDF

In the global warming context, we compared the thermal tolerance of several populations of the crustacean Gammarus pulex (Amphipoda: Gammaridae) along a latitudinal thermal gradient in the Rhône Valley. To disentangle the effect of regional (North vs. South) and local (site-specific) factors, the ecophysiological responses of populations were investigated at two levels of biological organisation: whole organism level considering body size [critical thermal maximum (CTmax), mean speed of locomotion (MS), time mobile (TM)] and organelle function level [mitochondrial respiratory control ratios (RCRs)].

View Article and Find Full Text PDF

Changes in land use and intensification of agricultural pressure have greatly accelerated the alteration of the landscape in most developed countries. These changes may greatly disturb the adjacent ecosystems, particularly streams, where the effects of pollution are amplified. In this study, we used the leaf litter breakdown rate to assess the functional integrity of stream ecosystems and river sediments along a gradient of either traditional extensive farming or a gradient of vineyard area.

View Article and Find Full Text PDF

In developed countries, changes in agriculture practices have greatly accelerated the degradation of the landscape and the functioning of adjacent aquatic ecosystems. Such alteration can in turn impair the services provided by aquatic ecosystems, namely the decomposition of organic matter, a key process in most small streams. To study this alteration, we recorded three measures of heterotrophic activity corresponding to microbial hydrolasic activity (FDA hydrolysis) and leaf litter breakdown rates with (k(c)) and without invertebrates (k(f)) along a gradient of contrasted agricultural pressures.

View Article and Find Full Text PDF

Studies of the influence of parasites on host fitness generally conclude that parasites have a strong negative effect on their hosts. In this study, we have investigated experimentally the role of Polymorphus minutus, an acanthocephalan parasite, on the salinity tolerance of the freshwater amphipod Gammarus roeseli, one of its intermediate hosts. Unexpectedly, P.

View Article and Find Full Text PDF

Scientists strive to develop efficient sampling protocols, reducing both the number of samples and processing time required, which can be adapted for use in a broad range of ecosystems. We investigated the accuracy and usefulness of artificial substrates in monitoring the impact of rising salinity on freshwater macroinvertebrate communities. We sampled seven sites along a salinity gradient (from 0.

View Article and Find Full Text PDF