Publications HAL de la structure Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés

2017

titre
2H/1H measurements of amphiboles and nominally anhydrous minerals (clinopyroxene, garnet and diamond) using high-temperature CF-EA-PY-IRMS
auteur
François Fourel, Christophe Lécuyer, Attila Demeny, Philippe Boulvais, Lutz Lange, Dorrit E. Jacob, Istvan Kovacs
article
Rapid Communications in Mass Spectrometry, 2017, 31 (24), pp.2066-2072. ⟨10.1002/rcm.7996⟩
resume
Rationale - We have used a high-precision, high-efficiency method for the measurement of the H/ H ratios of hydrous silicates (amphiboles) and nominally anhydrous minerals (NAM) such as clinopyroxene, garnet and diamond, which are usually extremely resistant to pyrolysis. This opens up new fields of investigation to better understand the conditions of formation for deep-Earth minerals. Methods - The technique described here involves Isotope Ratio Mass Spectrometry (IRMS) on-line in continuous flow mode with an Elemental Analyser (EA) using "purge and trap" technology rather than separation by conventional packed column gas chromatography (GC). The system is equipped with a special high-temperature furnace reaching 1500°C, with a longer hot zone and improved temperature stability. Emphasis is put on the efficiency of the system to reliably pyrolyse refractory minerals difficult to analyse with other conventional systems. Results - While conventional systems usually fail to generate hydrogen suitable for isotopic analyses, with the technique presented here we were able to measure H/ H ratios from four diamond samples (δ H = -60, -77, -84 and -79‰ V-SMOW; average SD = 4.5‰; n = 2), three garnet samples (δ H from -70 to -63‰), and nine clinopyroxenes (δ H from -92 to -58‰) associated with seven amphiboles (δ H from -76 to -27‰) from single mantle rock. Conclusions - The possibility of using such a system to reliably measure H/ H ratios from refractory minerals, which are usually extremely difficult to analyse, offers a new tool of investigation for providing us with unrivaled clues to study the deep interiors of Earth.
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DOI
DOI : 10.1002/rcm.7996
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titre
Heterogeneous responses of temperate-zone amphibian populations to climate change complicates conservation planning
auteur
E. Muths, T. Chambert, B. R. Schmidt, A. Miller, B. R. Hossack, Pierre Joly, Odile Grolet, M. Green, D. S. Pilliod, Marc Cheylan, R. N. Fisher, R. M. Mccaffery, J. Adams, J. Palen, J. Arntzen, J. Garwood, G. Fellers, J.-M. Thirion, Aurélien Besnard, E. H. Campbell Grant
article
Scientific Reports, 2017, 7 (17102), pp.1-10. ⟨10.1038/s41598-017-17105-7⟩
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The pervasive and unabated nature of global amphibian declines suggests common demographic responses to a given driver, and quantification of major drivers and responses could inform broad-scale conservation actions. We explored the influence of climate on demographic parameters (i.e., changes in the probabilities of survival and recruitment) using 31 datasets from temperate zone amphibian populations (North America and Europe) with more than a decade of observations each. There was evidence for an influence of climate on population demographic rates, but the direction and magnitude of responses to climate drivers was highly variable among taxa and among populations within taxa. These results reveal that climate drivers interact with variation in life-history traits and population-specific attributes resulting in a diversity of responses. This heterogeneity complicates the identification of conservation ‘rules of thumb’ for these taxa, and supports the notion of local focus as the most effective approach to overcome global-scale conservation challenges.
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DOI
DOI : 10.1038/s41598-017-17105-7
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titre
Geomorphic influence on intraspecific genetic differentiation and diversity along hyporheic corridors
auteur
Florian Malard, Cécile Capderrey, Benjamin Churcheward, David Eme, Bernard Kaufmann, Lara Konecny-Dupré, Jean-Paul Léna, Frédéric Liébault, Christophe Jean Douady
article
Freshwater Biology, 2017, 62 (12), pp.1955 - 1970. ⟨10.1111/fwb.13040⟩
resume
1. The hyporheic zone of rivers potentially acts as a dispersal corridor for ground- water organisms because it provides a spatially continuous interstitial habitat between isolated aquifers. Yet, the degree to which it can facilitate the move- ment of organisms has been hypothesized to vary in response to change in sedi- ment regime, which determines channel morphology. 2. In this study, we used microsatellite markers to test for a relationship between the genetic structure and diversity of the minute interstitial isopod Proasellus walteri and channel morphology along three nearby hyporheic corridors differing widely in their sediment regime. We predicted that genetic diversity would decrease and genetic structuring would increase as sediment supply-limited channels would become prominent features in the river corridor. The reason is that such channels have fewer and less suitable sedimentary habitats for migra- tion because they lack large depositional bedforms such as gravel bars. 3. Using genotypic data from seven microsatellite loci for a total of 713 individuals distributed among 25 demes, we found that demes had on average more alleles and were less differentiated in the river showing the most extensive alluvial depos- its and shortest length of sediment supply-limited channels. Population clusters were also of greater size, reaching up to 30 km in length. The longitudinal pattern of genetic differentiation in this sediment-rich river was best explained by hydro- logic distance and the longitudinal pattern of allelic richness was bell-shaped, as expected under a stepping-stone model with symmetrical migration. 4. The length of sediment supply-channels was more important than hydrologic dis- tance in explaining the longitudinal distribution of genetic differentiation in the two other corridors facing a sediment shortage. Allelic richness decreased mono- tonically upstream in the most sediment-poor river. This correlates with the expan- sion further downstream of sediment supply-limited channels in this river, which is likely to decrease animal movement and hence gene flow among demes. 5. Thisstudyprovidesthefirstevidencethatthedegreetowhichthehyporheiczone facilitates the movement of groundwater organisms varies greatly among rivers of contrasted geomorphology. Extending the application of riverscape genetics across a range of interstitial taxa and geomorphic settings holds much promise for assessing the contribution of the hyporheic zone to the dispersal of groundwater organisms.
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DOI : 10.1111/fwb.13040
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Ancient genetic bottleneck and Plio-Pleistocene climatic changes imprinted the phylobiogeography of European Black Pine populations
auteur
Krassimir Naydenov, Michel Naydenov, Alexander Alexandrov, Kole Vasilevski, Georgi Hinkov, Vlado Matevski, Biljana Nikolic, Venceslas Goudiaby, Dave Riegert, Despina Paitaridou, Andréas Christou, Irina Goia, Christopher Carcaillet, Adrian Escudero Alcantara, Cengiz Ture, Suleyman Gulcu, Veselka Gyuleva, Srdjan Bojovic, Lorenzo Peruzzi, Salim Kamary, Anatoly Tsarev, Faruk Bogunic
article
European Journal of Forest Research, 2017, 136 (5-6), pp.767 - 786. ⟨10.1007/s10342-017-1069-9⟩
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The historical changes in European Black Pine population size across the whole natural distribution in Europe and Asia Minor were analyzed facing the Plio-Pleistocene climatic fluctuations. Thirteen chloroplast SSRs and SNPs markers have been studied under the assumptions of “neutral evolution.” Populations and meta-populations had different histories of migration routes, and they were strongly affected by complex patterns of isolation, fragmentation, speciation, expansion (1.88–4.28 Ma), purification selection (2.09–21.41 Ma) and bottleneck (1.85–21.76 Ma). A significant number of populations (min. 29–41%) were in equilibrium for very long periods. Generally, the bottleneck revealed by chloroplast DNA is weaker than the bottleneck revealed by nuclear DNA. The N e immediately after the bottleneck reaches between 1820 and 3640 individuals. Generally, the historical effective population sizes shrink significantly for the Tertiary period from 10–15 up to 2.5 Ma in Western Europe (by 82%), followed by Asia Minor (69%) and the Balkan Peninsula (28%), likely resulting from important climatic changes. The rates and frequencies of stepwise westwards migration waves have been not sufficient to prevent isolation between the meta-populations and to suppress “sympatric speciation.” The migration was weak for the Pliocene, but was maximal for the Pleistocene, and finally silent for the present interglacial period, namely the Holocene.
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DOI : 10.1007/s10342-017-1069-9
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Fire ecology of a tree glacial refugium on a nunatak with a view on Alpine glaciers
auteur
Christopher Carcaillet, Olivier Blarquez
article
New Phytologist, 2017, 216 (4), pp.1281 - 1290. ⟨10.1111/nph.14721⟩
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. In paleoecology, the function of biomass as a fire driver has become a focus of attention in cold ecosystems, and concerns have been raised about climate in this context. Little is known about the fire frequency and fire–plant relationships during glaciation when woodlands were limited and the climate was cold. . Fire history and tree biomass were reconstructed from sedimentary charcoal and macrore- mains, respectively, archived in lake sediments from the western Alps. Two nunataks were investigated, both with lacustrine sediments covering the last 21 000 yr at least. . During the Last Glacial Maximum (LGM) and the Lateglacial, fires occurred only on the nunatak sheltering woody plants. Cembra pine (Pinus cembra) and larch (Larix decidua) sur- vived above glaciers during the LGM, thus evidencing a biological refugium and supporting the nunatak theory. . We highlighted a long-term relationship between fires and dominant trees over the last 21000yr, where fire frequencies track the global climate and the local changes in tree biomass. Glacial climate (dry, cold) does not rule out fires. Fuel load and composition were sig- nificant fire drivers, with cembra pine dominating during colder periods with rare fires, and larch during the warmer Holocene with frequent fires. These findings increase knowledge of fire ecology in cold environments, and open perspectives in tree population genetics by con- sidering new areas of tree glacial refugia in Europe.
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DOI : 10.1111/nph.14721
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Key parameters influencing metallic element mobility associated with sediments in a daily-managed reservoir
auteur
Franck Fremion, Brice Mourier, Alexandra Courtin-Nomade, Jean-François Lenain, Amal Annouri, Patrice Fondanèche, Thierry Hak, François Bordas
article
Science of the Total Environment, 2017, 605-606, pp.666-676. ⟨10.1016/j.scitotenv.2017.06.236⟩
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In a hydroelectric reservoir, sediments are subject to remobilization events, water-level fluctuations and physicochemical changes. Depending on their associated metallic content, surficial oxic to suboxic sediments could constitute a major source of metals. To identify the key parameters that control metallic elements in terms of their mobility and sensitivity to reservoir management, sediments were subject to resuspension and drying/wetting cycle experiments over a wide range of pH values, solid/liquid ratios (S/L) and redox (Eh) conditions. During these tests, special attention was also paid to the influence of pretreatments on samples, i.e., drying, aeration and the leachate composition (ultrapure water vs. natural water); on the preservation of the sediment characteristics; and especially on metallic element release. The results of this study show that the pH, S/L ratio and Eh parameters are key variables in metal solubilization; the pH influences metal mobility primarily through sorption-desorption phenomena as well as the dissolution of metallic-bearing phases, the S/L ratio modifies the sorption-desorption equilibria, and the Eh primarily affects the reducible sensitive phases and associated metallic elements through dissolution-precipitation processes. Under environmental conditions, evolution of these parameters can lead to a > 20% solubilization of the most mobile elements, i.e., As and Cd. These results are influenced by the sample pretreatment and experimental conditions. In fact, even if the solubilization patterns show no significant differences between dry and wet sediment depending on the physicochemical conditions, the magnitude of their release is significantly affected. Drying pretreatment induces changes in metal speciation, notably altering the distribution of the most weakly bound elements; there is almost half the amount of metallic elements associated with the exchangeable fraction in dry compared to wet sediments. The solubilization percentages were higher in the ultrapure phase than in reservoir water primarily due to the low pH, which influenced the sorption equilibria.
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DOI : 10.1016/j.scitotenv.2017.06.236
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Albian flora from Archingeay-Les Nouillers (Charente-Maritime): comparison and synthesis of Cretaceous meso- and macro-remains from the Aquitaine Basin (southwestern France)
auteur
Jean-David Moreau, Didier Néraudeau, Marc Philippe, Éric Dépré
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Geodiversitas, 2017, 39 (4), pp.729 - 740. ⟨10.5252/g2017n4a5⟩
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Over recent decades, diverse structures ascribed to angiosperms, bennettitaleans, conifers, cycads, ginkgophytes and pteridosperms have been reported from the Cretaceous deposits of the Aquitaine Basin (southwestern France). However, Albian macrofloras remain uncommon in Aquitania as well as in France. The clay from the Archingeay-Les Nouillers quarries is one of the rare deposits of the Aquitaine Basin to yield Albian plant meso- and macro-remains. Although Albian plant-bearing beds are not accessible any more in these quarries, samples collected from excavations conducted at the end of the XXth century were deposited in the collections of the University of Rennes 1. This paper provides a synthesis of the meso- and macro-remains contained in these collections, including angiosperm leaves and leafy conifer axes, dated as Late Albian. Providing here an inventory of the Cretaceous meso- and macro-remains from the Aquitaine Basin, we compare the Albian flora from Archingeay-Les Nouillers with pre-Albian, Albian, Cenomanian, and Turono-Coniacian floras from other localities in southwestern France.
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DOI
DOI : 10.5252/g2017n4a5
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titre
Can Soil Organic Carbon Fractions Be Used as Functional Indicators of Wetlands?
auteur
Charlotte Grasset, Célia Rodriguez, Pierre Marmonier, Cécile Delolme, Gudrun Bornette
article
Wetlands, 2017, 37 (6), pp.1195 - 1205. ⟨10.1007/s13157-017-0951-z⟩
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DOI : 10.1007/s13157-017-0951-z
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Drift, selection, or migration? Processes affecting genetic differentiation and variation along a latitudinal gradient in an amphibian
auteur
Maria Cortázar-Chinarro, Ella Z. Lattenkamp, Yvonne Meyer-Lucht, Émilien Luquet, Anssi Laurila, Jacob Höglund
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BMC Evolutionary Biology, 2017, 17 (189), pp.1-14. ⟨10.1186/s12862-017-1022-z⟩
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Background: Past events like fluctuations in population size and post-glacial colonization processes may influence the relative importance of genetic drift, migration and selection when determining the present day patterns of genetic variation. We disentangle how drift, selection and migration shape neutral and adaptive genetic variation in 12 moor frog populations along a 1700 km latitudinal gradient. We studied genetic differentiation and variation at a MHC exon II locus and a set of 18 microsatellites.Results: Using outlier analyses, we identified the MHC II exon 2 (corresponding to the β-2 domain) locus and one microsatellite locus (RCO8640) to be subject to diversifying selection, while five microsatellite loci showed signals of stabilizing selection among populations. STRUCTURE and DAPC analyses on the neutral microsatellites assigned populations to a northern and a southern cluster, reflecting two different post-glacial colonization routes found in previous studies. Genetic variation overall was lower in the northern cluster. The signature of selection on MHC exon II was weaker in the northern cluster, possibly as a consequence of smaller and more fragmented populations.Conclusion: Our results show that historical demographic processes combined with selection and drift have led to a complex pattern of differentiation along the gradient where some loci are more divergent among populations than predicted from drift expectations due to diversifying selection, while other loci are more uniform among populations due to stabilizing selection. Importantly, both overall and MHC genetic variation are lower at northern latitudes. Due to lower evolutionary potential, the low genetic variation in northern populations may increase the risk of extinction when confronted with emerging pathogens and climate change.
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DOI
DOI : 10.1186/s12862-017-1022-z
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Phylogeny, age structure, growth dynamics and colour pattern of the Salamandra algira algira population in the Edough Massif, northeastern Algeria
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Selma Bouzid, Lara Konecny, Odile Grolet, Christophe Jean Douady, Pierre Joly, Zihad Bouslama
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Amphibia-Reptilia, 2017, 38 (4), pp.461 - 471. ⟨10.1163/15685381-00003127⟩
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DOI : 10.1163/15685381-00003127
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Influence of oil palm monoculture on the taxonomic and functional composition of aquatic insect communities in eastern Brazilian Amazonia
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Ana Luiza-Andrade, Leandro Schlemmer Brasil, Naraiana Loureiro Benone, Yulie Shimano, Ana Paula Justino Farias, Luciano Fogaça Montag, Sylvain Dolédec, Leandro Juen
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Ecological Indicators, 2017, 82, pp.478 - 483. ⟨10.1016/j.ecolind.2017.07.006⟩
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Large scale palm oil plantations for the production of vegetable oil are among the most harmful agricultural activities to biodiversity, especially given their rapid expansion, worldwide. Many cases of species loss have already been recorded in Asian countries, although research is still incipient in the Amazon basin, and the environmental impacts of these monocultures on freshwater ecosystems in the Neotropical region are still poorly understood. The present study evaluated the effects of oil palm plantations on the physical structure of stream habitats and the resulting changes in the taxonomic and functional composition of aquatic insect communities. A total of 2100 specimens of the orders Ephemeroptera, Plecoptera and Trichoptera were collected during the present study, representing 40 genera and 16 families. The hypothesis tested was that the taxonomic and functional diversity of the orders Ephemeroptera, Plecoptera and Trichoptera (Insecta) decreases in streams surrounded by oil palm plantations in comparison with those embedded in forested areas. In the plantation streams, the taxonomic richness and composition, and the functional richness are modified significantly. Functional composition appeared unaltered despite reduced canopy cover associated with oil palm streams. These effects emphasize the importance of the riparian vegetation for the protection of the aquatic communities found in oil palm plantations. The maintenance of the riparian vegetation may mitigate the impacts of plantations, contributing to the conservation of insect communities and associated biodiversity.
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DOI : 10.1016/j.ecolind.2017.07.006
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Evaluating the accuracy of biodiversity changes through geologic times: from simulation to solution
auteur
Corentin Gibert Bret, Gilles Escarguel
article
Paleobiology, 2017, 43 (04), pp.667 - 692. ⟨10.1017/pab.2017.10⟩
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Estimating biodiversity and its variations through geologic time is a notoriously difficult task, due to several taphonomic and methodological effects that make the reconstructed signal potentially distinct from the unknown, original one. Through a simulation approach, we examine the effect of a major, surprisingly still understudied, source of potential disturbance: the effect of time discretization through biochronological construction, which generates spurious coexistences of taxa within discrete time intervals (i.e., biozones), and thus potentially makes continuous- and discrete-time biodiversity curves very different. Focusing on the taxonomic-richness dimension of biodiversity (including estimates of origination and extinction rates), our approach relies on generation of random continuous-time richness curves, which are then time-discretized to estimate the noise generated by this manipulation. A broad spectrum of data-set parameters (including average taxon longevity and biozone duration, total number of taxa, and simulated time interval) is evaluated through sensitivity analysis. We show that the deteriorating effect of time discretization on the richness signal depends highly on such parameters, most particularly on average biozone duration and taxonomic longevity because of their direct relationship with the number of false coexistences generated by time discretization. With several worst-case but realistic parameter combinations (e.g., when relatively short-lived taxa are analyzed in a long-ranging biozone framework), the original and time-discretized richness curves can ultimately show a very weak to zero correlation, making these two time series independent. Based on these simulation results, we propose a simple algorithm allowing the back-transformation of a discrete-time taxonomic-richness data set, as custo- marily constructed by paleontologists, into a continuous-time data set. We show that the reconstructed richness curve obtained this way fits the original signal much more closely, even when the parameter combination of the original data set is particularly adverse to an effective time-discretized reconstruction.
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DOI : 10.1017/pab.2017.10
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Life history tactics shape amphibians’ demographic responses to the North Atlantic Oscillation
auteur
Hugo Cayuela, Pierre Joly, Benedikt R. Schmidt, Julian Pichenot, Eric Bonnaire, Pauline Priol, Olivier Peyronel, Mathias Laville, Aurélien Besnard
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Global Change Biology, 2017, 23 (11), pp.4620 - 4638. ⟨10.1111/gcb.13672⟩
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Over the last three decades, climate abnormalities have been reported to be involved in biodiversity decline by affecting population dynamics. A growing number of studies have shown that the North Atlantic Oscillation (NAO) influences the demographic parameters of a wide range of plant and animal taxa in different ways. Life history theory could help to understand these different demographic responses to the NAO. Indeed, theory states that the impact of weather variation on a species’ demographic traits should depend on its position along the fast–slow continuum. In particular, it is expected that NAO would have a higher impact on recruitment than on adult survival in slow species, while the opposite pattern is expected occur in fast species. To test these predictions, we used long-term capture–recapture data- sets (more than 15,000 individuals marked from 1965 to 2015) on different sur- veyed populations of three amphibian species in Western Europe: Triturus cristatus, Bombina variegata, and Salamandra salamandra. Despite substantial intraspecific variation, our study revealed that these three species differ in their position on a slow–fast gradient of pace of life. Our results also suggest that the differences in life history tactics influence amphibian responses to NAO fluctuations: Adult survival was most affected by the NAO in the species with the fastest pace of life (T. cristatus), whereas recruitment was most impacted in species with a slower pace of life (B. variegata and S. salamandra). In the context of climate change, our findings suggest that the capacity of organisms to deal with future changes in NAO values could be closely linked to their position on the fast–slow continuum.
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DOI : 10.1111/gcb.13672
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What modulates animal longevity ? Fast and slow aging in bivalves as a model for the study of lifespan
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Pierre Blier, Doris Abele, Daniel Munro, Cyril Dégletagne, Enrique Rodriguez, Tory Hagen
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Seminars in Cell and Developmental Biology, 2017, 70, pp.130 - 140. ⟨10.1016/j.semcdb.2017.07.046⟩
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Delineating the physiological and biochemical causes of aging process in the animal kingdom is a highly active area of research not only because of potential benefits for human health but also because aging process is related to life history strategies (growth and reproduction) and to responses of organisms to environmental conditions and stress. In this synthesis, we advocate studying bivalve species as models for revealing the determinants of species divergences in maximal longevity. This taxonomic group includes the longest living metazoan on earth (Arctica islandica), which insures the widest range of maximum life span when shorter living species are also included in the comparative model. This model can also be useful for uncovering factors modulating the pace of aging in given species by taking advantages of the wide disparity of lifespan among different populations of the same species. For example, maximal lifespan in different populations of A islandica range from approximately 36 years to over 500 years. In the last 15 years, research has revealed that either regulation or tolerance to oxidative stress is tightly correlated to longevity in this group which support further investigations on this taxon to unveil putative mechanistic links between Reactive Oxygen Species and aging process.
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DOI : 10.1016/j.semcdb.2017.07.046
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Laboratory investigation of Fallopia × bohemica fruits dispersal by watercourses
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Quentin Rendu, Emmanuel Mignot, Nicolas Riviere, Barbara Lamberti-Raverot, Sara Puijalon, Florence Piola
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Environmental Fluid Mechanics, 2017, 17 (5), pp.1051 - 1065. ⟨10.1007/s10652-017-9537-9⟩
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Seed and fruit dispersal along watercourses favours the long-distance migration of invasive species, not only for aquatic or wetland species, but also for terrestrial wind- dispersed plants, like the Japanese knotweed. The present paper aims at investigating the role of watercourses in the dispersal of the knotweed due to its frequent occurrence on riverbanks and production of fertile achenes (type of fruit of the Japanese knotweed). This dispersal occurs along two steps after the fruits deposit on the water surface: floatation first and then sinking towards the bottom of the watercourse. Regarding the first step, the effects of agitation of the water, temperature, surface tension and luminosity on the achenes floatability are experimentally studied. While no influence of luminosity is observed, an increase of temperature greatly decreases the floating time. Floating time also decreases as the contact between water and the fruit is enhanced (through submersion of achenes, agitation of the water or lower surface tension). Regarding the second step, the fall velocity of the fruits in water at rest is measured and appears to be independent of the seed history (floating time). 3D helical motions are systematically observed with constant tangential velocity with respect to the falling velocity. The trajectory of the fruits in a shear flow is then measured and the evolution of their velocity components along the sinking process is discussed. Finally, the contribution of both steps to the long-distance migration of the seeds is estimated.
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DOI : 10.1007/s10652-017-9537-9
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Chronic stress, energy transduction, and free-radical production in a reptile
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Yann Voituron, Rémy Josserand, Jean-François Le Galliard, Claudy Haussy, Damien Roussel, Caroline Romestaing, Sandrine Meylan
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Oecologia, 2017, 185 (2), pp.195 - 203. ⟨10.1007/s00442-017-3933-1⟩
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Stress hormones, such as corticosterone, play a crucial role in orchestrating physiological reaction patterns shaping adapted responses to stressful environments. Concepts aiming at predicting individual and population responses to environmental stress typically consider that stress hormones and their effects on metabolic rate provide appropriate proxies for the energy budget. However, uncoupling between the biochemical processes of respiration, ATP production, and free-radical production in mitochondria may play a fundamental role in the stress response and associated life histories. In this study, we aim at dissecting sub-cellular mechanisms that link these three processes by investigating both whole-organism metabolism, liver mitochondrial oxidative phosphorylation processes (O2 consumption and ATP production) and ROS emission in Zootoca vivipara individuals exposed 21 days to corticosterone relative to a placebo. Corticosterone enhancement had no effect on mitochondrial activity and efficiency. In parallel, the corticosterone treatment increased liver mass and mitochondrial protein content suggesting a higher liver ATP production. We also found a negative correlation between mitochondrial ROS emission and plasma corticosterone level. These results provide a proximal explanation for enhanced survival after chronic exposure to corticosterone in this species. Importantly, none of these modifications affected resting whole-body metabolic rate. Oxygen consumption, ATP, and ROS emission were thus independently affected in responses to corticosterone increase suggesting that concepts and models aiming at linking environmental stress and individual responses may misestimate energy allocation possibilities.
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DOI : 10.1007/s00442-017-3933-1
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Effects of traffic noise on tree frog stress levels, immunity, and color signaling
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Mathieu Troïanowski, Nathalie Mondy, Adeline Dumet, Caroline Arcanjo, Thierry Lengagne
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Conservation Biology, 2017, 31 (5), pp.1132 - 1140. ⟨10.1111/cobi.12893⟩
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During the last decade, many studies have focused on the detrimental effects of noise pollution on acoustic communication. Surprisingly, although it is known that noise exposure strongly influences health in humans, studies on wildlife remain scarce. In order to gain insight into the consequences of traffic noise exposure, we experimentally manipulated traffic noise exposure as well as the endocrine status of animals to investigate physiological and phenotypic consequences of noise pollution in an anuran species. We showed that noise exposure increased stress hormone level and induced an immunosuppressive effect. In addition, both traffic noise exposure and stress hormone application negatively impacted H. arborea vocal sac coloration. Moreover, our results suggest profound changes in sexual selection processes because the best quality males with initial attractive vocal sac coloration were the most impacted by noise. Hence, our study suggests that the recent increases in anthropogenic noise worldwide might affect a broader range of animal species than previously thought, because of alteration of visual signals and immunity. Generalizing these results to other taxa is crucial for the conservation of biodiversity in an increasingly noisy world.
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DOI : 10.1111/cobi.12893
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Mitochondrial oxidative phosphorylation efficiency is upregulated during fasting in two major oxidative tissues of ducklings
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Pierre-Axel Monternier, Loïc Teulier, Jocelyne Drai, Aurore Bourguignon, Delphine Collin-Chavagnac, Frédéric Hervant, Jean-Louis Rouanet, Damien Roussel
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Comparative Biochemistry and Physiology - Part A: Molecular and Integrative Physiology, 2017, 212, pp.1 - 8. ⟨10.1016/j.cbpa.2017.06.018⟩
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Fasted endothermic vertebrates must develop physiological responses to maximize energy conservation and survival. The aim of this study was to determine the effect of 1-wk. fasting in 5-wk. old ducklings (Cairina moschata) from whole-body resting metabolic rate and body temperature to metabolic phenotype of tissues and mitochondrial coupling efficiency. At the level of whole organism, the mass-specific metabolic rate of ducklings was decreased by 40% after 1-wk. of fasting, which was associated with nocturnal Tb declines and shallow diurnal hypothermia during fasting. At the cellular level, fasting induced a large reduction in liver, gastrocnemius (oxidative) and pectoralis (glycolytic) muscle masses together with a fuel selection towards lipid oxidation and ketone body production in liver and a lower glycolytic phenotype in skeletal muscles. At the level of mitochondria, fasting induced a reduction of oxidative phosphorylation activities and an up-regulation of coupling efficiency (+ 30% on average) in liver and skeletal muscles. The present integrative study shows that energy conservation in fasted ducklings is mainly achieved by an overall reduction in mitochondrial activity and an increase in mitochondrial coupling efficiency, which would, in association with shallow hypothermia, increase the conservation of endogenous fuel stores during fasting.
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DOI : 10.1016/j.cbpa.2017.06.018
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Resources allocated to reproduction decrease at the range edge of an expanding population of an invasive amphibian
auteur
Julien Courant, Jean Secondi, Viviane Bereiziat, Anthony Herrel
article
Biological Journal of the Linnean Society, 2017, 122 (1), pp.157 - 165. ⟨10.1093/biolinnean/blx048⟩
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Predicting the magnitude and nature of changes in a species’ range is becoming ever more important as an increas- ing number of species are faced with habitat changes or are introduced to areas outside of the species’ native range. An organism’s investment in life-history traits is expected to change during range shifts or range expansion because populations encounter new ecological conditions. While simulation studies predict that dispersal and reproductive allocation should increase at the range edge, we suggest that reproductive allocation might decrease at the range edge due to energy allocation trade-offs. We studied the reproductive investment of an invasive amphibian, Xenopus laevis, and measured reproductive allocation in three clusters of populations distributed from the centre to the edge of the colonized range of X. laevis in France. Resource allocation was estimated with the scaled mass index of gonads of both sexes during the local period of reproduction of the species. The level of resources allocated to reproduction was lower at the periphery of the colonized range compared to the centre and may be the result of changes in trade- offs between life-history traits. Such a pattern could be explained by interspecific competition or enhanced invest- ment in dispersal capacity.
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DOI : 10.1093/biolinnean/blx048
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Evaluation des Risques Ecotoxicologiques liés à l’épandage de boues de STEP chaulées sur une parcelle agricole
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Gilles Donguy, Pascale Chenon
article
Environnement, Ingénierie & Développement, 2017, N°74 - septembre 2017, pp.1-12. ⟨10.4267/dechets-sciences-techniques.3643⟩
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Sewage sludge from urban wastewater plants can be applied on agricultural land in accordance to a regulatory framework established by a 1997 decree, under the responsibility of the producer of the sludge considered as waste. Under the impetus of the French Lime Association, a technical dossier for the creation of a new standard, based on the realization of an Ecotoxicological Risk Assessment (ERA) on limed sludge, was transmitted to ANSES, and led to the development of an AFNOR standard (NFU44-003) allowing the use of these sludge as soil improvers. The ERA, which typically involves four steps (problem formulation, characterization of exposure, characterization of effects, risk characterization), has been implemented using the "substances" approach to the terrestrial ecosystem, a typical scenario of spreading sludge on agricultural soil. Physicochemical analyzes were carried out on these sludges with regard to the following hazard tracers : 3 HAPs and 9 Trace Elements Metal. For each of these risk tracers, exposure (PEC) was characterized on the basis of a sludge dilution factor in agricultural soil, calculated for the so-called agricultural D1 (0.1 %) and a dose 5 times greater D5 (0.5 %), while ecotoxicological values (PNEC) were derived from international databases. For each substance, and for the exposure doses D1 and D5, the risk was characterized according to the quotient (PEC / PNEC) method of Technical Guidance Document (TGD). The results of the ERA suggest that there is no significant risk to the terrestrial ecosystem for exposure doses D1 and D5. To reinforce or refine this conclusion, the implementation of a "matrix" approach, closer to reality on the ground, and involving several urban sludges, would be desirable, not only for the terrestrial ecosystem but also for the nearby streams and groundwater underneath the cultivated area.
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DOI : 10.4267/dechets-sciences-techniques.3643
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Analysing movement behaviour and dynamic space-use strategies among habitats using multi-event capture-recapture modelling
auteur
Hugo Cayuela, Roger Pradel, Pierre Joly, Aurélien Besnard
article
Methods in Ecology and Evolution, 2017, 8 (9), pp.1124-1132. ⟨10.1111/2041-210X.12717⟩
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1. The environment of most species is heterogeneous at different spatial and temporal scales; this heterogeneity can have a direct effect on various components of fitness. As a consequence, individual space-use and movement strategies are central issues in ecology and conservation and receive considerable attention from researchers. 2. In the last 30 years, this issue has led to the development of capture–recapture models that allow movement between sites to be quantified, while handling imperfect detection. For studies involving numerous recapture sites in which the emphasis is on dispersal or migration rather than movement between particular sites, Lagrange et al. recently proposed a parsimonious CR multi-event model that contrasts individuals that move and individuals that stay in place, irrespective of the sites involved. 3. In this study, we developed a generalized version of this model to allow survival probability and movement probability to differ for different types of habitat to which the individual sites may be assigned. We investigated the potential of this new parameterization by studying the movements of an amphibian, the yellow-bellied toad (Bombina variegata), in a set of breeding and resting/foraging ponds. 4. Our capture–recapture multi-event model provides a highly flexible tool allowing users to model movements within and between several habitats. This approach can be potentially used to study movement behaviour and space-use strategies of a wide range of taxa.
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DOI : 10.1111/2041-210X.12717
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Miocene (Burdigalian) seawater and air temperatures estimated from the geochemistry of fossil remains from the Aquitaine Basin, France
auteur
Jean Goedert, Romain Amiot, Florent Arnaud-Godet, Gilles Cuny, François Fourel, Jean-Alexis Hernandez, Ulysse Pedreira-Segade, Christophe Lécuyer
article
Palaeogeography, Palaeoclimatology, Palaeoecology, 2017, 481, pp.14 - 28. ⟨10.1016/j.palaeo.2017.04.024⟩
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Construction work of the Highway A65 led the top of the Burdigalian ‘Molasses de l'Armagnac’ Formation to outcrop in two close localities near the town of Bazas and Marimbault, situated on the western edge of the Aquitaine Basin, France. From this formation, a rich fossil assemblage has been recovered and includes both marine and terrestrial fossil remains which offered the opportunity to reconstruct both seawater and terrestrial air temperatures at a regional scale during the Burdigalian. For this purpose, two sets of fossil samples representative of the whole assemblage have been selected for each locality. They include teeth and bones of sharks, fish, rays, reptiles and mammals, as well as tests of sea urchins and shells of bivalves. First, we performed rare earth element (REE) analyses of 53 apatite samples from both localities in order to characterize the diagenetic history of the assemblage. We then analysed the oxygen isotope composition of 49 biogenic apatite phosphate samples and 6 biogenic carbonate samples representing both marine and terrestrial organisms. Using published isotopic fractionation equations, both seawater and terrestrial air temperatures were reconstructed. Calculated seawater temperatures using phosphate and carbonate isotopic thermometers are + 23 ± 4 °C and + 25 ± 1 °C respectively for the locality of Mendouillet (Bazas) and + 24 ± 4 °C and + 26 ± 1 °C respectively for the locality of Monbalon-Miron (Marimbault). Calculated terrestrial air temperatures are + 18 ± 2 °C for the locality of Mendouillet and + 17 ± 2 °C for the locality of Monbalon-Miron. These regional temperatures are in good agreement with seawater and terrestrial temperatures calculated for other European localities of contemporaneous periods. These results also fit the global climatic context of the Mid-Miocene Climatic Optimum starting at the end of the Burdigalian. Even though the global climatic conditions were warmer than today during the end of the Burdigalian, calculated continental and seawater thermal gradient at mid-latitude appear to have been comparable to present-day ones.
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DOI : 10.1016/j.palaeo.2017.04.024
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Mobbing calls: a signal transcending species boundaries
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Mylène Dutour, Jean-Paul Léna, Thierry Lengagne
article
Animal Behaviour, 2017, 131, pp.3 - 11. ⟨10.1016/j.anbehav.2017.07.004⟩
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When they detect a predator, some prey exhibit mobbing behaviour and produce mobbing calls that quickly draw a mixed conspecific and heterospecific group against the predator. While the efficiency of this strategy is often linked to interspecific communication, it raises the question of how animals recognize these signals as mobbing calls. It is usually suggested that associative learning about a predator when heterospecific mobbing calls are heard plays a crucial role in communication among species. Alternatively, phylogenetic conservation or evolutionary convergence could also explain this communication process. To determine whether prior experience is required to express a mobbing response, we conducted playback experiments with four European passerine species: great tit, Parus major, blue tit, Cyanistes caeruleus, coal tit, Periparus ater, and common chaffinch, Fringilla coelebs. The aim of the study was to examine whether they would respond to the mobbing signals of several North American passerines. As expected, because natural selection might shape a strong response to conspecific mobbing calls, our focal species reacted more strongly towards their own mobbing calls than towards those of American species. Nevertheless, for the three European species of tit, prior experience of heterospecific mobbing calls was not required to elicit a response. Additionally, for great tit and chaffinch, we found that acoustic similarity could explain behavioural responses to allopatric species. In contrast, such similarity was probably not the main mechanism underlying the response for the other two European species. Heterospecific response to mobbing calls probably involved many different mechanisms. Further studies focusing on each of these should allow us to understand their relative contribution to heterospecific communication.
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DOI : 10.1016/j.anbehav.2017.07.004
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Water dispersal of the invasive complex Fallopia : The role of achene morphology
auteur
Barbara Lamberti-Raverot, Florence Piola, Mélanie Thiébaut, Ludovic Guillard, Félix Vallier, Sara Puijalon
article
Flora, 2017, 234, pp.150 - 157. ⟨10.1016/j.flora.2017.07.009⟩
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DOI : 10.1016/j.flora.2017.07.009
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Tolerance of Japanese knotweed s.l. to soil artificial polymetallic pollution: early metabolic responses and performance during vegetative multiplication
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Serge Michalet, Soraya Rouifed, Thomas Pellassa-Simon, Manon Fusade-Boyer, Guillaume Meiffren, Sylvie Nazaret, Florence Piola
article
Environmental Science and Pollution Research, 2017, 24 (26), pp.20897-20907. ⟨10.1007/s11356-017-9716-8⟩
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The expansion of invasive Japanese Knotweed s.l. is of particular concern because of its aptitudes to rapidly colonize diverse environments, especially anthropized habitats generally characterized by their pollution with heavy metals. Whether the presence of heavy metals impacts the performance traits of this plant is a central question to better understand its invasive properties, though no controlled approach to assess these effects were yet reported. In this aim, we undertook greenhouse experiments where rhizome fragments of Japanese Knotweed s.l. (Fallopia japonica and Fallopia x bohemica) were grown during 1 and 3 months, in soil pot artificially polluted or not with heavy metals added in mixture (Cd, Cr, Pb, Zn). Our results showed that (i) the presence of heavy metals delayed rhizome regeneration and induced lowered plant part weights but did not affect plant height after three months; (ii) the effect of metals on the metabolic profiles of belowground part extracts was only detectable after 1 month and not after 3 months of growth, though, it was possible to highlight the effect of metals independently of time and genotype for root extracts, and torosachrysone seemed to be the most induced compound; (iii) the hybrid genotype tested was able to accumulate relatively high concentrations of metals, over or close to the highest reported ones for this plant for Cr, Cd and Zn, whereas Pb was not accumulated. These findings evidence that the presence of heavy metals in soil has a low impact on Fallopia spp. overall performance traits during rhizome regeneration, and has a rather stimulating effect on plant growth depending on pollution level.
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DOI : 10.1007/s11356-017-9716-8
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Estradiol Protects Against Cardiorespiratory Dysfunctions and Oxidative Stress in Intermittent Hypoxia
auteur
Sofien Laouafa, Alexandra Ribon-Demars, François Marcouiller, Damien Roussel, Aida Bairam, Vincent Pialoux, Vincent Joseph
article
Sleep, 2017, 40 (8), pp.1-13. ⟨10.1093/sleep/zsx104⟩
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Study Objectives: We tested the hypothesis that estradiol (E2) protects against cardiorespiratory disorders and oxidative stress induced by chronic intermittent hypoxia (CIH) in adult female rats. Methods: Sprague-Dawley female rats (230-250 g) were ovariectomized and implanted with osmotic pumps delivering vehicle or E2 (0.5 mg/kg/d). After 14 days of recovery, the rats were exposed to CIH (21%-10% O2: 8 h/d, 10 cycles per hour) or room air (RA). After 7 days of CIH or RA exposure, we measured arterial pressures (tail cuff), metabolic rate (indirect calorimetry), minute ventilation, the frequency of sighs and apneas at rest, and ventilatory responses to hypoxia and hypercapnia (whole body plethysmography). We collected the cerebral cortex, brainstem, and adrenal glands to measure the activity of NADPH and xanthine oxidase (pro-oxidant enzymes), glutathione peroxidase, and the mitochondrial and cytosolic superoxide dismutase (antioxidant enzymes) and measured lipid peroxidation and advanced oxidation protein products (markers of oxidative stress). Results: CIH increased arterial pressure, the frequency of apnea at rest, and the hypoxic and hypercapnic ventilatory responses and reduced metabolic rate. CIH also increased oxidant enzyme activities and decreased antioxidant activity in the cortex. E2 treatment reduced body weight and prevented the effects of CIH. Conclusions: E2 prevents cardiorespiratory disorders and oxidative stress induced by CIH. These observations may help to better understand the underlying mechanisms linking menopause and occurrence of sleep apnea in women and highlight a potential advantage of hormone therapy.
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DOI : 10.1093/sleep/zsx104
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Landscape variables influence taxonomic and trait composition of insect assemblages in Neotropical savanna streams
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Diego Pareiras de Castro, Sylvain Dolédec, Marcos Callisto
article
Freshwater Biology, 2017, 62 (8), pp.1472 - 1486. ⟨10.1111/fwb.12961⟩
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1. Stream invertebrate assemblages are structured by environmental factors acting at multiple spatial scales. Identifying the spatial scale that most influences the species–environment relationships is a major goal of community ecology. 2. We evaluated the importance of catchment and site scales and associated envi- ronmental variables in shaping Ephemeroptera, Plecoptera and Trichoptera (EPT) assemblages in Neotropical savanna headwater streams. 3. Sampling sites were associated with 20 catchment-scale variables that depicted land cover and land use as well as natural geophysical variables such as altitude and climate. Site-scale habitat was characterised by 55 variables that described habitat hydromorphology, substrate, flow, canopy, in-stream cover and water quality. EPT traits were assessed using 28 categories of 7 biological traits, which represented the best available current knowledge for EPT in Neotropical savanna streams. 4. We analysed the relationships between the catchment- and site-scale habitat variables and the taxonomic and trait composition of insect assemblages using 1,760 samples collected in 160 stream sites. 5. Catchment- and site-scale variables both explained significant variation in EPT taxon and trait composition. Substrate, habitat hydromorphology and land use most influenced variation in taxonomic composition, whereas trait composition was mainly affected by land use. Catchment geographic position explained less assemblage variation. 6. To our knowledge, this study is the first assessment of the impact of catchment- and site-scale variables on the trait and taxon composition of stream insect assemblages in Neotropical savanna streams. It highlights the need for better regional biological knowledge of invertebrates to generate more general trait- based approaches in freshwater ecosystem conservation.
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DOI : 10.1111/fwb.12961
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Oxygen isotopes suggest elevated thermometabolism within multiple Permo-Triassic therapsid clades
auteur
Kévin Rey, Romain Amiot, François Fourel, Fernando Abdala, Frédéric Fluteau, Nour-Eddine Jalil, Jun Liu, Bruce Rubidge, Roger Mh Smith, Jean-Sébastien Steyer, Pia A Viglietti, Xu Wang, Christophe Lécuyer
article
eLife, 2017, 6, pp.e28589. ⟨10.7554/eLife.28589⟩
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The only true living endothermic vertebrates are birds and mammals, which produce and regulate their internal temperature quite independently from their surroundings. For mammal ancestors, anatomical clues suggest that endothermy originated during the Permian or Triassic. Here we investigate the origin of mammalian thermoregulation by analysing apatite stable oxygen isotope compositions (d18Op) of some of their Permo-Triassic therapsid relatives. Comparing of the d18Op values of therapsid bone and tooth apatites to those of co-existing non-therapsid tetrapods, demonstrates different body temperatures and thermoregulatory strategies. It is proposed that cynodonts and dicynodonts independently acquired constant elevated thermometabolism, respectively within the Eucynodontia and Lystrosauridae + Kannemeyeriiformes clades. We conclude that mammalian endothermy originated in the Epicynodontia during the middle-late Permian. Major global climatic and environmental fluctuations were the most likely selective pressures on the success of such elevated thermometabolism.
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DOI : 10.7554/eLife.28589
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Increased mitochondrial energy efficiency in skeletal muscle after long-term fasting: its relevance to animal performance
auteur
Aurore Bourguignon, Anaïs Rameau, Gaëlle Toullec, Caroline Romestaing, Damien Roussel
article
Journal of Experimental Biology, 2017, 220 (13), pp.2445 - 2451. ⟨10.1242/jeb.159087⟩
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In the final stage of fasting, skeletal muscle mass and protein content drastically decrease when the maintenance of efficient locomotor activity becomes crucial for animals to reactivate feeding behaviour and survive a very long period of starvation. As mitochondrial metabolism represents the main physiological link between the endogenous energy store and animal performance, the aim of this study was to determine how a very long, natural period of fasting affected skeletal muscle mitochondrial bioenergetics in king penguin (Aptenodytes patagonicus) chicks. Rates of mitochondrial oxidative phosphorylation were measured in pectoralis permeabilized fibres and isolated mitochondria. Mitochondrial ATP synthesis efficiency and the activities of respiratory chain complexes were measured in mitochondria isolated from pectoralis muscle. Results from long-term (4–5 months) naturally fasted chicks were compared with those from short-term (10 day) fasted birds. The respiratory activities of muscle fibres and isolated mitochondria were reduced by 60% and 45%, respectively, on average in long-term fasted chicks compared with short-term fasted birds. Oxidative capacity and mitochondrial content of pectoralis muscle were lowered by long-term fasting. Bioenergetic analysis of pectoralis muscle also revealed that mitochondria were, on average, 25% more energy efficient in the final stage of fasting (4–5 months) than after 10 days of fasting (short-term fasted birds). These results suggest that the strong reduction in respiratory capacity of pectoralis muscle was partly alleviated by increased mitochondrial ATP synthesis efficiency. Such oxidative phosphorylation optimization can impact animal performance, e.g. the metabolic cost of locomotion or the foraging efficiency.
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DOI : 10.1242/jeb.159087
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Xylobolus subpileatus, a specialized basidiomycete functionally linked to old canopy gaps
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Adrien Taudière, Jean-Michel Bellanger, A. Moreau, Christopher Carcaillet, Ananda Christophe, T. Læssøe, C. Panaïotis, F. Richard
article
Canadian Journal of Forest Research, 2017, 47 (7), pp.965 - 973. ⟨10.1139/cjfr-2016-0521⟩
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Documenting succession in forest canopy gaps provides insights into the ecological processes governing the temporal dynamics of species within communities. We analyzed the fruiting patterns of a rare but widely distributed saproxylic macro- mycete, Xylobolus subpileatus, during the ageing of natural canopy gaps in oak forests. In one of the last remaining Quercus ilex L. old-growth forests (on the island of Corsica, western Mediterranean basin), we systematically recorded and conducted molecular analyses of X. subpileatus basidiomes in 80 dated natural canopy gaps representing a 45-year long sequence of residence time of tree logs on the forest floor. Xylobolus subpileatus fruited exclusively on Q. ilex logs. The probability of fruiting of X. subpileatus significantly increases during the process of wood decomposition to reach its maximum in the oldest gaps, approximately 40 years after treefall. In contrast, the abundance and the richness of saprobic and ectomycorrhizal fruitbodies decrease as canopy gaps age. Our results emphasize the high ecological specialization of X. subpileatus. They also highlight the imperative need to conserve the last patches of old-growth Mediterranean forests to secure the persistence of this endangered and functionally unique macromycete whose presence is highly dependent on old wood in advanced stages of decomposition.
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DOI : 10.1139/cjfr-2016-0521
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Morphological disparity and systematic revision of the eocrinoid genus Rhopalocystis (Echinodermata, Blastozoa) from the Lower Ordovician of the central Anti-Atlas (Morocco)
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Ninon Allaire, Elise Nardin, Emmanuel Laurent Olivier Martin, Romain Vaucher, Gilles Escarguel, Bertrand Lefebvre
article
Journal of Paleontology, 2017, 91 (04), pp.685 - 714. ⟨10.1017/jpa.2017.6⟩
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The genus Rhopalocystis (Eocrinoidea, Blastozoa) is characterized by both a short stratigraphic range (Fezouata Shale, middle Tremadocian to middle Floian, Lower Ordovician) and a reduced geographic extension (Agdz-Zagora area, central Anti-Atlas, Morocco). Since the original description of its type species (R. destombesi Ubaghs, 1963), three successive revisions of the genus Rhopalocystis have led to the erection of nine additional species. The morphological disparity within this genus is here critically reassessed on the basis of both historical material and new recently collected samples. The detailed examination of all specimens, coupled with morphometric and cladistic analyses, points toward a relatively strong support for five morphotypes. A systematic revision of Rhopalocystis is thus suggested, with only five valid taxa: R. destombesi, R. fraga Chauvel, 1971, R. grandis Chauvel, 1971, R. havliceki Chauvel, 1978, and R. zagoraensis Chauvel, 1971. The five others are considered as junior synonyms (R. dehirensis Chauvel and Régnault, 1986, R. lehmani Chauvel and Régnault, 1986, R. sp. A, R. sp. B, and R. sp. C).
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DOI : 10.1017/jpa.2017.6
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Diversity of aquatic macroinvertebrates in relationship with the environmental factors of a lotic ecosystem in tropical region: the Sô river in South-East of Benin (West Africa)
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Zinsou Cosme Koudenoukpo, Antoine Chikou, Ibrahim Imorou Toko, Sertge Hubert Zebaze Togouet, Siméon Tchakonté, Rodrigue Hazoume, Christophe Piscart
article
Journal of Entomology and Zoology Studies, 2017, 5, pp.1 - 10
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The present study was aimed to study the diversity of aquatic macroinvertebrate populations in relation to the abiotic parameters of the Sô River. For this purpose, aquatic macroinvertebrates were sampled monthly between February 2016 and April 2017 on 12 sampling stations and in various habitats along the Sô River. Similarly, twenty environmental variables were measured to assess the environmental characteristics of Sô river. The recorded fauna consists of 2053 individuals corresponding to 44 families and 61 taxa belonging to three main zoological groups (Arthropods, Molluscs, Annelids). The stand population showed that Coleoptera (17.06%), Basomatophora (14.19%), Heteroptera (11.37%), Odonata (10.26%), Mesogasteropoda (9.01%) and Decapoda (9%) are the most abundant orders. Another oders constitute only a small fraction of the total fauna harvested. The redundancy analysis performed shows that abiotic parameters that strongly influence taxonomic diversity and taxon abundance are: current velocity, nitrogen and phosphorus compounds, mineralization parameters and canopy.
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Phylogeography and historical introgression in smoothtail nine-spined sticklebacks, Pungitius laevis (Gasterosteiformes: Gasterosteidae)
auteur
Cui Wang, Takahito Shikano, Henri Persat, Juha Merilä
article
Biological Journal of the Linnean Society, 2017, 121 (2), pp.340 - 354. ⟨10.1093/biolinnean/blw036⟩
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Pleistocene glaciations have strongly affected the biogeography of many species residing in periglacial and previously glaciated regions. Smoothtail nine-spined sticklebacks (Pungitius laevis) have three highly divergent mitochondrial lineages in France, one of which shares the same mitochondrial cluster with a congener P. pungitius. To understand if interspecific introgression has happened between the two species, we carried out phylogeographic and population genetic analyses using mitochondrial and nuclear gene sequences. Our results indicated asymmetric mitochondrial introgression from P. pungitius to P. laevis and genetic admixture of these species in one of the P. laevis lineages, suggesting historical hybridization. Deep intraspecific mitochondrial divergence within P. laevis in central and southern France mostly coinciding with major drainages suggests that these areas were important glacial refugia for the species explaining the observed intraspecific divergence. The historical hybridization between P. laevis and P. pungitius likely occurred in a refugium at central France, and the newly formed P. laevis lineage spread northward during postglacial recolonization. The study adds to the long list of species showing complete mitogenome capture owing to historical hybridizations, and highlights the reticulate nature of population differentiation in taxa subject to postglacial range-expansions.
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DOI : 10.1093/biolinnean/blw036
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Oxygen isotope fractionation between bird bone phosphate and drinking water
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Romain Amiot, Delphine Angst, Serge Legendre, Eric Buffetaut, François Fourel, Jan Adolfssen, Aurore André, Ana Voica Bojar, Aurore Canoville, Abel Barral, Jean Goedert, Stanislaw Halas, Nao Kusuhashi, Ekaterina Pestchevitskaya, Kevin Rey, Aurélien Royer, Antônio Álamo Feitosa Saraiva, Bérengère Savary-Sismondini, Jean-Luc Siméon, Alexandra Touzeau, Zhonghe Zhou, Christophe Lécuyer
article
The Science of Nature Naturwissenschaften, 2017, 104:47 (5-6), pp.1-13. ⟨10.1007/s00114-017-1468-2⟩
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Oxygen isotope compositions of bone phos- phate (δ18Op) were measured in broiler chickens reared in 21 farms worldwide characterized by contrasted lati- tudes and local climates. These sedentary birds were raised during an approximately 3 to 4-month period, and local precipitation was the ultimate source of their drink- ing water. This sampling strategy allowed the relationship to be determined between the bone phosphate δ18Op values (from 9.8 to 22.5‰ V-SMOW) and the local rainfall δ18Ow values estimated from nearby IAEA/WMO stations (from −16.0 to −1.0‰ V-SMOW). Linear least square fitting of data provided the following isotopic fractionation equation: δ18Ow = 1.119 (±0.040) δ18Op − 24.222 (±0.644); R2 = 0.98. The δ18Op–δ18Ow couples of five extant mallard ducks, a common buzzard, a European herring gull, a common ostrich, and a greater rhea fall within the predicted range of the equa- tion, indicating that the relationship established for extant chickens can also be applied to birds of various ecologies and body masses. Applied to published oxygen isotope com- positions of Miocene and Pliocene penguins from Peru, this new equation computes estimates of local seawater similar to those previously calculated. Applied to the basal bird Confuciusornis from the Early Cretaceous of Northeastern China, our equation gives a slightly higher δ18Ow value com- pared to the previously estimated one, possibly as a result of lower body temperature. These data indicate that caution should be exercised when the relationship estimated for mod- ern birds is applied to their basal counterparts that likely had a metabolism intermediate between that of their theropod dino- saur ancestors and that of advanced ornithurines.
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DOI : 10.1007/s00114-017-1468-2
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Chironomidae of the Holarctic region: a comparison of ecological and functional traits between North America and Europe
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Sonia R.Q. Serra, Manuel A.S. Graça, Sylvain Dolédec, Maria João Feio
article
Hydrobiologia, 2017, 794 (1), pp.273-285. ⟨10.1007/s10750-017-3102-x⟩
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Chironomidae (Diptera) are widespread, abundant, diverse and ubiquitous, and include genera and species that are distributed across the Holarctic region. However, the geographical barriers between continents should have resulted in intraspecific pop- ulation differentiation with reflection on individual biological and ecological traits. Our aim was to test for potential differences in Chironomidae species/genus and traits between the Nearctic and Palearctic regions. We compared the Chironomidae trait information gathered in two databases; one database was devel- oped in Europe and the other in North America. Common genera and species of both databases were selected, and the common traits were adjusted into the same trait categories. Data were transformed into presence/absence and divided into Eltonian (biological/functional) and Grinnellian (ecological) traits. Common genera and common species were analyzed using Fuzzy correspondence analysis (FCA). Differences between databases occur for all trait domains. Yet, Eltonian traits showed lower level of concordance than Grinnellian traits at the species level. Different biological characteristics in the Nearctic and Palearctic regions may indicate that Chironomidae have different adaptions to similar ecological environments due to intraspecific variabil- ity or even trait plasticity.
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DOI : 10.1007/s10750-017-3102-x
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Atrial fibrillation is associated with hypermethylation in human left atrium, and treatment with decitabine reduces atrial tachyarrhythmias in spontaneously hypertensive rats
auteur
R. Doñate Puertas, E. Meugnier, C. Romestaing, C. Rey, E. Morel, J. Lachuer, N. Gadot, A. Scridon, C. Julien, F. Tronc, B. Chapuis, C. Valla, A. Janin, Luciano Pirola, A. Mejat, S. Rome, Philippe Chevalier
article
Translational Research, The Journal of Laboratory and Clinical Medicine, 2017, 184, pp.57 - 67.e5. ⟨10.1016/j.trsl.2017.03.004⟩
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Atrial fibrillation (AF) is the most common cardiac arrhythmia. As the molecular mechanisms underlying the pathology are largely unknown, this cardiac arrhythmia remains difficult to treat. To identify specific molecular actors involved in AF, we have performed a transcriptomic analysis on left atrium (LA) from patients with valvular heart disease with or without AF. We showed that 1627 genes had altered basal expression level in LA tissue of AF patients compared with the control group. The significantly enriched gene ontology biological process ‘‘anatomical structure morphogenesis’’ contained the highest number of genes in line with changes in structure that occur when the human heart remodels following AF development (ie, LA dilatation and interstitial fibrosis). We then focused the study on Pitx2 (paired-like homeodomain 2), being the most altered transcription factor in LA from AF patients and from which compelling evidence have indicated that its reduced expression can be considered as a marker for the disease. In addition, its expression was inversely correlated with LA size. We demonstrated that AF is associ- ated with Pitx2 promoter hypermethylation both in humans and arrhythmic aging spontaneously hypertensive rats. Chronic administration of a DNA methylation inhib- itor (ie, 5-Aza-20-deoxycitidine) improved ECG arrhythmic profiles and superoxide dismutase activities and reduced fibrosis in the left ventricle of spontaneously hyper- tensive rats. Taken together, these data support the notion that AF is associated with epigenetic changes in LA and provide a proof-of-concept that hypomethylating agents have to be considered in the treatment of atrial arrhythmias
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DOI : 10.1016/j.trsl.2017.03.004
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Global realized niche divergence in the African clawed frog Xenopus laevis
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Dennis Rödder, Flora Ihlow, Julien Courant, Jean Secondi, Anthony Herrel, Rui Rebelo, G. J. Measey, Francesco Lillo, F. A. de Villiers, Charlotte de Busschere, Thierry Backeljau
article
Ecology and Evolution, 2017, 7 (11), pp.4044 - 4058. ⟨10.1002/ece3.3010⟩
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Although of crucial importance for invasion biology and impact assessments of climate change, it remains widely unknown how species cope with and adapt to environmental conditions beyond their currently realized climatic niches (i.e., those climatic conditions existing populations are exposed to). The African clawed frog Xenopus laevis, native to southern Africa, has established numerous invasive populations on multiple continents making it a pertinent model organism to study environmental niche dynamics. In this study, we assess whether the realized niches of the invasive populations in Europe, South, and North America represent subsets of the species’ realized niche in its native distributional range or if niche shifts are traceable. If shifts are traceable, we ask whether the realized niches of invasive populations still contain signatures of the niche of source populations what could indicate local adaptations. Univariate comparisons among biocli- matic conditions at native and invaded ranges revealed the invasive populations to be nested within the variable range of the native population. However, at the same time, invasive populations are well differentiated in multidimensional niche space as quantified via n-dimensional hypervolumes. The most deviant invasive population are those from Europe. Our results suggest varying degrees of realized niche shifts, which are mainly driven by temperature related variables. The crosswise projection of the hypervolumes that were trained in invaded ranges revealed the south-western Cape region as likely area of origin for all invasive populations, which is largely congruent with DNA sequence data and suggests a gradual exploration of novel climate space in invasive populations.
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DOI : 10.1002/ece3.3010
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Network analysis for species management in rivers networks: Application to the Loire River
auteur
Audrey Chaput-Bardy, Nicolas Alcala, Jean Secondi, Séverine Vuilleumier
article
Biological Conservation, 2017, 210, pp.26 - 36. ⟨10.1016/j.biocon.2017.04.003⟩
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Forecasting the colonization process is important for wildlife managers who supervise the reintroduction of endangered species or control the spread of invasive species. Patch connectivity is thus critical to predicting the fates of expanding populations. Connectivity in river networks results from river dendritic structure and dispersal modality of organisms. Both factors may strongly affect the colonization process and the efficiency of conservation action plans. Based on empirical data, we simulated, using a simplified model with limited number of parameters, the colonization of a large river network, the Loire River, by the native Eurasian beaver and the invasive African clawed frog. For each species, we inferred model parameters (dispersal behavior and distances) by comparing the simulated and the observed distributions. Using network theory, we evaluated the efficiency of alternative conservation strategies to prevent or promote colonization of the river network. Network robustness to fragmentation and disturbance was also assessed. The model accurately predicted > 70% of the observed species ranges. Conservation strategies that selectively protect habitat patches with the highest connectivity values provide a weak advantage at preventing connectivity loss compared to random protection strategies. In contrast, the targeted destruction of highly connected patches had a much stronger effect on the fragmentation of the network than the random removal of habitat patches. Spatial network topology strongly contributes to determining colonization patterns of large river watersheds. Network theory allows tests for robustness of rivers to fragmentation and disturbance, and identification of strategies for conservation planning.
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DOI : 10.1016/j.biocon.2017.04.003
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Urban underground development confronted by the challenges of groundwater resources: Guidelines dedicated to the construction of underground structures in urban aquifers
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Guillaume Attard, Yvan Rossier, Thierry Winiarski, Laurent Eisenlohr
article
Land Use Policy, 2017, 64, pp.461-469. ⟨10.1016/j.landusepol.2017.03.015⟩
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Urban subsoil provides space, groundwater, geothermal energy and geomaterials, and the importance underlying the management of this strategic space is well-known. In the context of vertical urban growth, groundwater management is a crucial issue. In particular, operational tools dedicated to urban planners are needed in urban areas prone to conflicts over use in order to aid the decision-making process. The aim of this paper is to propose guidelines dedicated to urban underground development in view to incorpo- rating groundwater resource management. These guidelines are supported by analyses of the scientific literature dealing with: (1) the impacts caused by underground structures on urban groundwater, and (2) the quantitative overview of urban groundwater resources at the operational level in terms of quan- tity, quality and temperature. Finally, perspectives are discussed regarding the research work needed to ensure better management of urban groundwater resources confronted by underground development.
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DOI : 10.1016/j.landusepol.2017.03.015
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Assessing anthropogenic pressures on streams: A random forest approach based on benthic diatom communities
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Floriane Larras, Romain Coulaud, Edwige Gautreau, Elise Billoir, Juliette Tison-Rosebery, Philippe Usseglio-Polatera
article
Science of the Total Environment, 2017, 586, pp.1101 - 1112. ⟨10.1016/j.scitotenv.2017.02.096⟩
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Benthic diatoms have been widely used to assess the ecological status of freshwater ecosystems, especially in the context of recent international water framework directive policies (e.g. the WFD). Despite diatom-based indices are known to respond fastly to water quality degradation, they are not designed to precisely identify the nature of pressures co-occurring in the environment. Based on large scale monitoring data, we aimed at building models able to estimate the risk of stream impairment by many types of anthropogenic pressures from taxonomy based and trait-based characteristics of diatom assemblages. Random forest models were built to individually evaluate the impairment risk of diatom assemblages for six chemical and five hydromorphological or land-use related pressure categories. Eight models provided good impairment risk assessment (Area Under the Curve >= 0.70). Under multi-pressure scenarios, models built for chemical pressures exhibited a better accuracy than hydromorphological or land-use related ones. Models were able to detect both ecological restoration and degradation, based on long-term surveys. These models have been implemented in a R user-friendly routine, to help stream managers to early identify degrading processes and prioritize management actions. (C) 2017 Elsevier B.V. All rights reserved.
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DOI : 10.1016/j.scitotenv.2017.02.096
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Plant dispersal traits determine hydrochorous species tolerance to connectivity loss at the landscape scale
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Lisa Favre-Bac, Barbara Lamberti-Raverot, Sara Puijalon, Aude Ernoult, Francoise Burel, Ludovic Guillard, Cendrine Mony
article
Journal of Vegetation Science, 2017, 28 (3), pp.605-615. ⟨10.1111/jvs.12518⟩
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Aims: Landscape fragmentation has strong negative consequences on biodiversity. In networks of linear elements, connectivity loss results in a decreased length of connected elements and increased potential barriers, directly impacting the ability of plants to disperse. However, species vary in their tolerance to connectivity loss, likely due to differences in dispersal strategies. We investigated whether species tolerance to decreased ditch network connectivity is determined by seed traits. We selected, as a case study, water-dispersed plant species in a ditch network.Location: Ditch network in an intensive agricultural area in northern France.Methods: We selected 27 sites of 500 m 9 500 m, where we calculated connectivity indices based on the length of connected ditches, intersections and culvert number. For each parameter, we calculated plant tolerance levels by analysing species changes in occurrence in response to change in connectivity values. Concurrently, we measured in laboratory conditions five seed traits involved in plant movement and establishment in standing aquatic systems and analysed their explanatory power in plant tolerance to fragmentation.Results: All traits were significantly related to at least one component of ditch network connectivity. We interpreted the following two strategies in plant tolerance to connectivity loss from the results: (1) in networks where the connected network length was short, plants displayed short-distance dispersal with less efficient sexual reproduction, probably in favour of local vegetative multiplication; and (2) in networks with a high density of culverts or intersections, plants displayed seeds with reduced local retention, where seeds had the capacity to overcome long and frequent trapping events. In highly branched networks, plants also exhibited higher germination rates, promoting seed establishment when trapped along the banks. Seed capacity to be dispersed by wind at the water surface was only a marginal factor in plant tolerance to fragmentation.Conclusions: Connectivity loss acted as a filter on species seed traits. The results of our study offer an enhanced understanding of plant dispersal in fragmented standing aquatic networks and emphasize the importance of developing functional approaches in landscape studies.
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DOI : 10.1111/jvs.12518
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Functionally dissimilar neighbors accelerate litter decomposition in two grass species
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Lou Barbe, Vincent Jung, Andreas Prinzing, Anne‐kristel Bittebière, Olaf Butenschoen, Cendrine Mony
article
New Phytologist, 2017, 214 (3), pp.1092-1102. ⟨10.1111/nph.14473⟩
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Plant litter decomposition is a key regulator of nutrient recycling. In a given environment, decomposition of litter from a focal species depends on its litter quality and on the efficiency of local decomposers. Both may be strongly modified by functional traits of neighboring species, but the consequences for decomposition of litter from the focal species remain unknown.We tested whether decomposition of a focal plant's litter is influenced by the functional-trait dissimilarity to the neighboring plants. We cultivated two grass species (Brachypodium pinnatum and Elytrigia repens) in experimental mesocosms with functionally similar and dissimilar neighborhoods, and reciprocally transplanted litter.For both species, litter quality increased in functionally dissimilar neighborhoods, partly as a result of changes in functional traits involved in plant–plant interactions. Furthermore, functional dissimilarity increased overall decomposer efficiency in one species, probably via complementarity effects.Our results suggest a novel mechanism of biodiversity effects on ecosystem functioning in grasslands: interspecific functional diversity within plant communities can enhance intraspecific contributions to litter decomposition. Thus, plant species might better perform in diverse communities by benefiting from higher remineralization rates of their own litter.
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DOI : 10.1111/nph.14473
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Mobbing behaviour in a passerine community increases with prevalence in predator diet
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Mylène Dutour, Jean-Paul Léna, Thierry Lengagne
article
Ibis, 2017, 159 (2), pp.324 - 330. ⟨10.1111/ibi.12461⟩
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DOI : 10.1111/ibi.12461
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Nanoparticle transport in water-unsaturated porous media: effects of solution ionic strength and flow rate
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Dieuseul Prédélus, Laurent Lassabatère, Cédric Louis, Hélène Gehan, Thomas Brichart, Thierry Winiarski, Rafaël Angulo-Jaramillo
article
Journal of Nanoparticle Research, 2017, 19 (3), ⟨10.1007/s11051-017-3755-4⟩
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This paper presents the influence of ionic strength and flow on nanoparticle (NP) retention rate in an unsaturated calcareous medium, originating from a heterogeneous glaciofluvial deposit of the region of Lyon (France). Laboratory columns 10 cm in diameter and 30 cm in length were used. Silica nanoparticles (Au-SiO2-FluoNPs), with hydrodynamic diameter rang- ing from 50 to 60 nm and labeled with fluorescein derivatives, were used to simulate particle transport, and bromide was used to characterize flow. Three flow rates and five different ionic strengths were tested. The transfer model based on fractionation of water into mobile and immobile fractions was coupled with the attachment/detachment model to fit NPs breakthrough curves. The results show that increasing flow velocity induces a decrease in nanoparticle retention, probably as the result of several physical but also geochemical fac- tors. The results show that NPs retention increases with ionic strength. However, an inversion of retention occurs for ionic strength >5.10−2 M, which has been scarcely observed in previous studies. The measure of zeta potential and DLVO calculations show that NPs may sorb on both solid-water and air-water interfaces. NPs size distribution shows the potential for nanoparti- cle agglomeration mostly at low pH, leading to entrap- ment in the soil pores. These mechanisms are highly sensitive to both hydrodynamic and geochemical con- ditions, which explains their high sensitivity to flow rates and ionic strength.
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DOI : 10.1007/s11051-017-3755-4
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Unlimited fuel wood during the middle Mesolithic (9650–8300 cal. yr BP) in northern Sweden: Fuel typology and pine-dominated vegetation inferred from charcoal identification and tree-ring morphology
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Christopher Carcaillet
article
The Holocene, 2017, 27 (9), pp.1370 - 1378. ⟨10.1177/0959683617693894⟩
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A fuel wood analysis based on the ‘Principle of Least Effort’ helps to decipher the ecological limitations imposed on prehistoric hunter-gatherers. This study is based on botanical identification of wood charcoal from ‘Swedish middle Mesolithic’ archaeological sites dating from between ca. 9650 and 8300 cal. yr BP in northern Sweden, a period when the land was freshly released from ice cover. Charcoal fragments were analysed based on their anatomical and morphological features and anomalies. Tree-ring thickness gives an indication of the growing conditions experienced by woody plants, the tree-ring curvature provides an indication of the diameter of the pieces of wood used for fuel and the percentage of fragments with spiral thickening indicates the importance of compression or tension wood, which is related to branches or trunks stressed by snow burden or wind. Among the main woody species, the assemblages are dominated by Pinus sylvestris with some Salicaceae trees (Populus, Salix). Large wood pieces including branches were used as fuel. Several taxa were rarely recorded (Betula, Sorbus, Ericaceae) or not observed (Juniperus, Hippophae, Alnus) although their presences were expected based on other local palaeobotanical records. Because (1) charcoal of Pinus sylvestris abounds despite not being a good fuel wood and (2) certain consumable or combustible taxa are scarce (Betula) or are only present at certain sites (Salicaceae), it appears that Mesolithic hunters were not selective when choosing wood for fuel, although wood was not a limiting factor for the first settlers in northern Sweden. Pine tree-ring width range is within the modern range for the same species, indicating growing conditions similar to those experienced today. The results suggest the occurrence of woodland, probably in the lowlands. During the early-Holocene, trees rapidly covered the land after the ice-sheet melted, facilitating the life of Mesolithic hunters following reindeer herds.
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DOI : 10.1177/0959683617693894
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Unexpected Early Triassic marine ecosystem and the rise of the Modern evolutionary fauna.
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Arnaud Brayard, L.J. Krumenacker, Joseph P. Botting, James F. Jenks, Kevin G. Bylund, Emmanuel Fara, Emmanuelle Vennin, Nicolas Olivier, Nicolas Goudemand, Thomas Saucède, Sylvain Charbonnier, Carlo Romano, Larisa Doguzhaeva, Ben Thuy, Michael Hautmann, Daniel A. Stephen, Christophe Thomazo, Gilles Escarguel
article
Science Advances , 2017, 3 (2), pp.e1602159. ⟨10.1126/sciadv.1602159⟩
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In the wake of the end-Permian mass extinction, the Early Triassic (~251.9 to 247 million years ago) is portrayed as an environmentally unstable interval characterized by several biotic crises and heavily depauperate marine benthic ecosystems. We describe a new fossil assemblage—the Paris Biota—from the earliest Spathian (middle Olenekian, ~250.6 million years ago) of the Bear Lake area, southeastern Idaho, USA. This highly diversified assemblage documents a remarkably complex marine ecosystem including at least seven phyla and 20 distinct metazoan orders, along with algae. Most unexpectedly, it combines early Paleozoic and middle Mesozoic taxa previously unknown from the Triassic strata, among which are primitive Cambrian-Ordovician leptomitid sponges (a 200–million year Lazarus taxon) and gladius-bearing coleoid cephalopods, a poorly documented group before the Jurassic (~50 million years after the Early Triassic). Additionally, the crinoid and ophiuroid specimens show derived anatomical characters that were thought to have evolved much later. Unlike previous works that suggested a sluggish postcrisis recovery and a low diversity for the Early Triassic benthic organisms, the unexpected composition of this exceptional assemblage points toward an early and rapid post-Permian diversification for these clades. Overall, it illustrates a phylogenetically diverse, functionally complex, and trophically multileveled marine ecosystem, from primary producers up to top predators and potential scavengers. Hence, the Paris Biota highlights the key evolutionary position of Early Triassic fossil ecosystems in the transition from the Paleozoic to the Modern marine evolutionary fauna at the dawn of the Mesozoic era.
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DOI : 10.1126/sciadv.1602159
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Experimental climate warming alters the relationship between fungal root symbiosis and Sphagnum litter phenolics in two peatland microhabitats
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Philippe Binet, Soraya Rouifed, Vincent Jassey, Marie-Laure Toussaint, Geneviève Chiapusio
article
Soil Biology and Biochemistry, 2017, 105, pp.153-161. ⟨10.1016/j.soilbio.2016.11.020⟩
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Belowground interactions between plants and microorganisms are involved in numerous ecosystems processes such as carbon and nutrient cycling. Understanding their responses to on-going climate warming is thus of paramount importance to better predict future ecosystem functioning. We hypothesized that climate warming alters the interactions between Sphagnum litter phenolics and the fungal root symbiosis of the Ericale plant Andromeda polifolia in a Jura mountain peatland (France). We initiate a climate warming treatment (+1°C) in April 2008 in two microhabitats (lawns and hummocks). We measured polyphenolic contents, mycorrhizal and dark septate endophyte (DSE) root colonization, phenoloxidase and peroxidase activities in the A. polifolia rhizosphere from 2010 to 2012. We found that four years of warming modulated rhizospheric parameters (fungal root symbiosis and enzyme activities) of A. polifolia, but the response differed between microhabitats. Enzyme activities and fungal root colonization displayed different responses to warming according to the microhabitats. DSE root colonization increased and peroxidase activities decreased in warmed Hummocks while they remained stable in warmed lawns. We found a significant positive correlation between DSE root colonization and litter phenolics recovered in both microhabitats but only under in ambient conditions. On the contrary, significant negative correlation was observed between mycorrhizae and litter phenolics recovered in warmed plots while no relationship was found in control plots. Our work thus provides evidences that interplay between phenolics from Sphagnum litter and fungal symbiosis of an Ericale species in peatlands was affected by climate warming. It highlights different plant biological responses to climate warming according to peatland microhabitats and confirm that belowground activities are crucial to understand the response of peatlands to climate change.
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DOI : 10.1016/j.soilbio.2016.11.020
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New national and regional bryophyte records, 50
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L.T. Ellis, Claudine Ah-Peng, M. Aleffi, K. Baráth, M. Bruguès, E. Ruiz, W.R. Buck, I.V. Czernyadjeva, P. Erzberger, L.B. Fantecelle, G. F. Peñaloza-Bojaca, C.A.T. Araújo, B.A. Oliveira, A.S. Maciel-Silva, N.J.M. Gremmen, S.L. Guo, Terry A. Hedderson, E. February, Nicholas Wilding, V. Hugonnot, M. Kirmaci, H. Kürschner, Marc Lebouvier, A. Mesterházy, R. Ochyra, M. Philippe, V. Plášek, Z. Skoupá, S. Poponessi, D. Gigante, R. Venanzoni, K.K. Rawat, V. Sahu, A.K. Asthana, M. S. Sabovljević, A.D. Sabovljevic, A. Schäfer-Verwimp, S. Wierzcholska
article
Journal of Bryology, 2017, 39 (1), pp.99-114. ⟨10.1080/03736687.2016.1259931⟩
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DOI : 10.1080/03736687.2016.1259931
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The role of heterogeneous lithology in a glaciofluvial deposit on unsaturated preferential flow – a numerical study
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Erij Ben Slimène, Laurent Lassabatère, Jiří Šimůnek, Thierry Winiarski, Rémy Gourdon
article
Journal of Hydrology and Hydromechanics, 2017, 65 (3), ⟨10.1515/johh-2017-0004⟩
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An understanding of preferential flow in the vadose zone is crucial for the prediction of the fate of pollutants. Infiltration basins, developed to mitigate the adverse effects of impervious surfaces in urban areas, are established above strongly heterogeneous and highly permeable deposits and thus are prone to preferential flow and enhanced pollutant transport. This study numerically investigates the establishment of preferential flow in an infiltration basin in the Lyon suburbs (France) established over a highly heterogeneous glaciofluvial deposit covering much of the Lyon region. An investigation of the soil transect (13.5 m long and 2.5 m deep) provided full characterization of lithology and hydraulic properties of present lithofacies. Numerical modeling with the HYDRUS-2D model of water flow in the transect was used to identify the effects of individual lithofacies that constitute the deposit. Multiple scenarios that considered different levels of heterogeneity were evaluated. Preferential flow was studied for several values of infiltration rates applied after a long dry period. The numerical study shows that the high contrast in hydraulic properties of different lithofacies triggers the establishment of preferential flow (capillary barriers and funneled flow). Preferential flow develops mainly for low water fluxes imposed at the surface. The role of individual lithofacies in triggering preferential flow depends on their shapes (layering versus inclusions) and their sizes. While lenses and inclusions produce preferential flow pathways, the presence of the surface layer has no effect on the development of preferential flow and it only affects the effective hydraulic conductivity of the heterogeneous transect.
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DOI : 10.1515/johh-2017-0004
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Macroporal heterogeneity influence on solute transport process in porous media: experiments on model soil and modeling with Lattice‐Boltzmann method
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Stéphane Batany, Pierre-Emmanuel Peyneau, Béatrice Bechet, Laurent Lassabatère, Pamela Françoise Faure, Patrick Dangla
article
La Houille Blanche - Revue internationale de l'eau, 2017, 3, pp.32-38. ⟨10.1051/lhb/2017019⟩
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Flow and solute transport modeling in porous media is an important issue for the monitoring of pollutant contaminations in soils or retention ponds. It is often necessary to take into account macroporal type heterogeneities. For this purpose, several numerical models use double or multi permeability concepts in order to characterize different permeabilities of a porous medium. However classical models seem to underestimate the impact of the preferential path induced by a macropore. This impact has to be extended in the surrounding porous matrix for the good fitting of experimental data. This study proposes to understand hydraulic and mass exchange mechanisms between the macropore and the porous matrix, by using a model porous media made of glass beads, and by using the lattice-Boltzmann method for flow simulations. First results show the influence of flow rate on the apparition of an inflection on breakthrough curves. Results show that molecular diffusion, higher in this case, causes higher mass transfer from the macropore to the porous matrix. Moreover, simulations show that the preferential flow is extended to the porous matrix in a zone having the same dimension than the macropore. These results emphasize that the macropore influence has to be extented in the porous matrix for flow and the diffusive exchange zone depends on the molecular diffusion coefficient of the tracer.
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DOI : 10.1051/lhb/2017019
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Sediment type rules the response of aquatic plant communities to dewatering in wetlands
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Mélissa de Wilde, Sara Puijalon, Gudrun Bornette
article
Journal of Vegetation Science, 2017, 28 (1), pp.172-183. ⟨10.1111/jvs.12473⟩
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QuestionsThe effect of dewatering on aquatic plant communities may vary with sediment properties, such as particle size and organic matter content, as both control water retention in the sediment during dewatering. No study has tested how sediment type affects the short-term response of plant communities to dewatering. We hypothesized that for the same dewatering event: (1) organic, silt and coarse sediments rank along a gradient of water deficit, with which community resistance and resilience decrease; (2) species survival during the event depend on their known ecological affinity for water; and (3) a peak in species richness associated with an intermediate water deficit occurs in silty habitats. LocationRiverine wetlands in the floodplain of the Ain River, France. MethodsEighteen sampling units were defined, set over three sediment types: gravel-dominated coarse sediment, silt and organic matter-dominated sediment. For each sediment type, three sampling units were permanently aquatic, and three sampling units underwent summer dewatering. A survey of species cover was conducted in each sampling unit at four times: before summer dewatering, at the beginning of the event, at the end of the event and 2months after rewetting. Community resistance and resilience were assessed, as were changes over time in the proportions of species according their water affinity (hydrophytes, amphiphytes and helophytes, documented from the floras), and the effect of dewatering on species renewal and richness. ResultsThe sediment type affected aquatic plant community resistance and resilience, with increasing disturbance intensity for silty, followed by coarse compared with organic sediment. Organic sediment retained water efficiently during dewatering, supporting high community resistance, with the maintenance of amphiphytes and more tolerant hydrophytes. On silty sediment, disturbance was sufficiently high to cause the disappearance of hydrophyte vegetative parts, but propagules rapidly sprouted after rewetting, suggesting their preservation in the sediment and enabling good community resilience. On coarse sediment, a decrease in resident amphiphyte abundance, together with helophyte colonization and maintenance after rewetting were observed. Coarse sediment is not favourable to propagule survival, explaining the low community resilience. Contrary to our hypothesis, a linear positive relationship between disturbance intensity and species richness was observed after dewatering. ConclusionThe present study demonstrates that a simple description of sediment type allows prediction of dewatering impact on aquatic plant communities: organic, silt and coarse sediments were ranked along a gradient of water deficit, along which resistance and resilience decreased.
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DOI : 10.1111/jvs.12473
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Cold acclimation allows Drosophila flies to maintain mitochondrial functioning under cold stress
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Hervé Colinet, David Renault, Damien Roussel
article
Insect Biochemistry and Molecular Biology, 2017, 80, pp.52-60. ⟨10.1016/j.ibmb.2016.11.007⟩
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Environmental stress generally disturbs cellular homeostasis. Researchers have hypothesized that chilling injury is linked to a shortage of ATP. However, previous studies conducted on insects exposed to nonfreezing low temperatures presented conflicting results. In this study, we investigated the mitochondrial bioenergetics of Drosophila melanogaster flies exposed to chronic cold stress (4 °C). We assessed mitochondrial oxygen consumption while monitoring the rate of ATP synthesis at various times (0, 1, 2, and 3 days) during prolonged cold stress and at two assay temperatures (25 and 4 °C). We compared organelle responses between cold-susceptible and cold-acclimated phenotypes. Continuous exposure to low temperature provoked temporal declines in the rates of mitochondrial respiration and ATP synthesis. Respiratory control ratios (RCRs) suggested that mitochondria were not critically uncoupled. Nevertheless, after 3 days of continuous cold stress, a sharp decline in the mitochondrial ATP synthesis rate was observed in control flies when they were assayed at low temperature. This change was associated with reduced survival capacity in control flies. In contrast, cold-acclimated flies exhibited high survival and maintained higher rates of mitochondrial ATP synthesis and coupling (i.e., higher RCRs). Adaptive changes due to cold acclimation observed in the whole organism were thus manifested in isolated mitochondria. Our observations suggest that cold tolerance is linked to the ability to maintain bioenergetics capacity under cold stress.
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DOI : 10.1016/j.ibmb.2016.11.007
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Biological denitrification inhibition (BDI) with procyanidins induces modification of root traits, growth and N status in Fallopia x bohemica
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Clément Bardon, Franck Poly, Feth El Zahar Haichar, Xavier Leroux, Laurent Simon, Guillaume Meiffren, Gilles Comte, Soraya Rouifed, Florence Piola
article
Soil Biology and Biochemistry, 2017, 107, pp.41-49. ⟨10.1016/j.soilbio.2016.12.009⟩
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Nitrogen (N) limits plant growth in many ecosystems and denitrification is a major source of N loss from soils. Fallopia spp. is an invasive plant species complex adapted to low-fertility soils, which is responsible for biological denitrification inhibition (BDI) through the production of procyanidins. However, the extent to which procyanidins can affect Fallopia spp. via BDI has not yet been shown. We investigated how procyanidins can generate plant trait modifications in Fallopia x bohemica by adding them, or not, to soil mesocosms planted, or not, with F. x bohemica. Soil denitrification enzyme activity (DEA), soil substrate induced respiration (SIR), nitrification enzyme activity (NEA), N-mineralization and total N, and NO3− concentrations were measured in the soil of planted mesocosms. NO3− concentrations were measured in unplanted mesocosms. Leaf and root N contents and above- and belowground plant traits were measured. In unplanted soils, procyanidins induced a six-fold increase in NO3−. Procyanidins inhibited DEA but not SIR, NEA and N-mineralization in planted soil. Procyanidins increased root N content marginally and biomass allocation to roots, while modifying root traits associated with an increase in nutrient acquisition capacity. Our results suggest that a plant-soil feedback related to BDI could result from procyanidin production in Fallopia spp..
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DOI : 10.1016/j.soilbio.2016.12.009
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Augustin Augier’s Botanical Tree: Transcripts and translations of two unknown source
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Nils Hellström, Gilles André, Marc Philippe
article
Huntia, a Journal of Botanical History, 2017, 16 (1), pp.17-38
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Augustin Augier’s “Arbre botanique” (1801) is one of the earliest known family tree diagrams to represent the natural system. As such it is frequently cited in the literature on historical systematics, where it is generally framed as a precursor to later, evolutionary trees. While ignorance concerning the author’s identity long complicated efforts at interpreting and placing his tree into context, in the course of our recent establishment of Augier’s biography, we discovered two previously unknown writings in which Augier discussed the Botanical Tree: a letter he sent to the National Institute in Paris in 1801 and a serialized article he published in Valence in 1809. These texts shed considerable light on how its author intended the Botanical Tree to be used and help to clarify how genealogical metaphors could serve as classificatory resources before the rise of evolutionary theory—and from within an explicitly religious worldview.
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Comparing Beerkan infiltration tests with rainfall simulation experiments for hydraulic characterization of a sandy-loam soil
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Simone Di Prima, Vincenzo Bagarello, Laurent Lassabatère, Rafael Angulo-Jaramillo, Inmaculada Bautista, Maria Burguet, Artemi Cerdà, Massimo Iovino, Massimo Prosdocimi
article
Hydrological Processes, 2017, 31 (20), pp.3520 - 3532. ⟨10.1002/hyp.11273⟩
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Saturated soil hydraulic conductivity, Ks, data collected by ponding infiltrometer methods and usual experimental procedures could be unusable for interpreting field hydrological processes and particularly rainfall infiltration. The Ks values determined by an infiltrometer experiment carried out by applying water at a relatively large distance from the soil surface could however be more appropriate to explain surface runoff generation phenomena during intense rainfall events. In this study, a link between rainfall simulation and ponding infiltrometer experiments was established for a sandy‐loam soil. The height of water pouring for the infiltrometer run was chosen, establishing a similarity between the gravitational potential energy of the applied water, Ep, and the rainfall kinetic energy, Ek. To test the soundness of this procedure, the soil was sampled with the Beerkan estimation of soil transfer parameters procedure of soil hydraulic characterization and two heights of water pouring (0.03 m, i.e., usual procedure, and 0.34 m, yielding Ep = Ek). Then, a comparison between experimental steady‐state infiltration rates, isR, measured with rainfall simulation experiments determining runoff production and Ks values for the two water pouring heights was carried out in order to discriminate between theoretically possible (isR ≥ Ks) and impossible (isR < Ks) situations. Physically possible Ks values were only obtained by applying water at a relatively large distance from the soil surface, because isR was equal to 20.0 mm h−1 and Ks values were 146.2–163.9 and 15.2–18.7 mm h−1 for a height of water pouring of 0.03 and 0.34 m, respectively. This result suggested the consistency between Beerkan runs with a high height of water pouring and rainfall simulator experiments. Soil compaction and mechanical aggregate breakdown were the most plausible physical mechanisms determining reduction of Kswith height. This study demonstrated that the height from which water is poured onto the soil surface is a key parameter in infiltrometer experiments and can be adapted to mimic the effect of high intensity rain on soil hydraulic properties.
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DOI : 10.1002/hyp.11273
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Immune challenges and visual signalling in tree frogs
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Julia L. Desprat, Thierry Lengagne, Nathalie Mondy
article
The Science of Nature Naturwissenschaften, 2017, 104 (21), pp.1-9. ⟨10.1007/s00114-017-1436-x⟩
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In animals, mate-choice is often based on sexual signals that carry information and help the receiver make the best choice to improve the receiver’s fitness. Orange visual sexual signals have been hypothesised to carry im- mune information because they are often due to caroten- oid pigments which are also involved in immunity re- sponse. Although many studies have focused on the direct relationships between coloration and immunocompetence, few studies have simultaneously studied immunocompe- tent response and coloration variation after an immune challenge. We tested this hypothesis on starved and ad libitum-fed males of the European tree frog Hyla arborea. Our results show that male coloration is not a reliable indicator of its immune response capacity in this species. However, after an immune challenge induced by a PHA (Phaseolus vulgaris phytohaemagglutinin) injection, starved males presented a significant coloration loss and this alteration was related to the immune response inten- sity. Taken together, these results suggest that the brighter (lighter) coloration may be used as a cue by female to exclude males with a recent immune challenge, due to diseases or parasites for example.
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DOI : 10.1007/s00114-017-1436-x
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Four species within the supercolonial ants of the Tapinoma nigerrimum complex revealed by integrative taxonomy (Hymenoptera: Formicidae)
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Berhard Seifert, Dario d'Eustacchio, Bernard Kaufmann, Massimiliano Centorame, Pedro Lorite, Maria Vittoria Modica
article
Myrmecological News, 2017, 24, pp.123-144. ⟨10.25849/myrmecol.news_024:123⟩
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The West and Central Mediterranean ants known for 50 years under the name Tapinoma nigerrimum (NYLANDER, 1856) have attracted attention because of their efficient chemical weapons, impressive supercolonies and potential to limit the spreading of the Argentine Ant Linepithema humile (MAYR, 1868). The paper shows that the T. nigerrimum complex consists of at least four clearly separable species which differ in morphology of all castes, colony demo- graphy, geographic distribution, invasive potential and mtDNA data. Species delimitation by means of Nest Centroid Clustering, considering 20 quantitative phenetic characters in 159 nest samples, resolved four coincident clusters in both female and male castes which are classified as T. nigerrimum, T. magnum MAYR, 1861, T. ibericum SANTSCHI, 1925, and T. darioi sp.n. The exploratory data analyses NC-Ward clustering and NC-k-means clustering showed a mean dis- agreement from the final species hypothesis between 0 and 2.7% in workers on the nest sample level, whereas the clas- sification error of a linear discriminant analysis was 4.2% in 533 worker individuals. The four phenetic clusters were basically confirmed by analysis of the COI segment of mtDNA with the smallest mean K2p genetic distance of 1.8% observed in T. darioi sp.n. against T. magnum, and the largest one of 4.0% in T. nigerrimum against T. ibericum. These data suggest a species divergence between late Pliocene and early Pleistocene (3.3 - 1.5 Ma). The mtDNA haplotypes of nine phenotypically ideal T. darioi sp.n. supercolonies, found at three sites in southern France, and Italy were placed within the T. magnum cluster. Among four alternative scenarios discussed for these mismatches, hybridization events in the younger evolutionary history with subsequent unidirectional genomic purging of nuDNA was proposed to be the most likely explanation. Tapinoma nigerrimum is monodomous to moderately polydomous with aggression between neigh- bouring colonies, whereas T. magnum, T. ibericum, and T. darioi sp.n. are supercolonial with a potential to become invasive pest ants through introduction by human commerce. For Europe north of 48° N, T. magnum could establish populations in nine cities in Germany, Belgium, and the Netherlands, whereas T. ibericum is known so far from one site in South England only, and T. darioi sp.n. from one city in the Netherlands. The differential zoogeography and biology of the four species and ways of species delimitation are outlined and discussed. Tapinoma darioi sp.n. is described as new.
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DOI : 10.25849/myrmecol.news_024:123
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The interaction between wetland nutrient content and plant quality controls aquatic plant decomposition
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Charlotte Grasset, L. H. Levrey, C. Delolme, F. Arthaud, Gudrun Bornette
article
Wetlands Ecology and Management, 2017, 25 (2), pp.211 - 219. ⟨10.1007/s11273-016-9510-2⟩
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We conducted an in situ decomposition experiment to better understand how habitat nutrient content controls aquatic plant decomposition and, more precisely, to determine the relative importance of the wetland conditions in decomposition, and the intrinsic degradability of plant tissues. We collected the green leaves of three aquatic plant species with contrasting plant strategies from three wetlands of differing nutrient contents, and allowed them to decompose in seven wetlands along a nutrient gradient. The plant mass loss was higher for competitive and ruderal species collected in nutrient richer wetlands as well as when they were led to decompose in nutrient richer wetlands. Plant water content correlated with mass loss for the competitive and ruderal species, which may explain the increase in mass loss with increasing nutrient content in the collection wetlands. Litter decomposition rate may be enhanced by wetland eutrophication, because of both the modification of wetland decomposition conditions and by changes in plant tissue quality.
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DOI : 10.1007/s11273-016-9510-2
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Are invasive populations characterized by a broader diet than native populations?
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Julien Courant, Solveig Vogt, Raquel M Marques, John Measey, Jean Secondi, Rui Rebelo, André de Villiers, Flora Ihlow, Charlotte de Busschere, Thierry Backeljau, Dennis Rödder, Anthony Herrel
article
PeerJ, 2017, 5:e3250, pp.1-16. ⟨10.7717/peerj.3250⟩
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Background. Invasive species are among the most significant threats to biodiversity. The diet of invasive animal populations is a crucial factor that must be considered in the context of biological invasions. A broad dietary spectrum is a frequently cited characteristic of invasive species, allowing them to thrive in a wide range of environments. Therefore, empirical studies comparing diet in invasive and native populations are necessary to understand dietary requirements, dietary flexibility, and the associated impacts of invasive species.Methods. In this study, we compared the diet of populations of the African clawed frog, Xenopus laevis in its native range, with several areas where it has become invasive. Each prey category detected in stomach contents was assigned to an ecological category, allowing a comparison of the diversity of ecological traits among the prey items in the diet of native and introduced populations. The comparison of diets was also performed using evenness as a niche breadth index on all sampled populations, and electivity as a prey selection index for three out of the six sampled populations.Results. Our results showed that diet breadth could be either narrow or broad in invasive populations. According to diet and prey availability, zooplankton was strongly preferred in most cases. In lotic environments, zooplankton was replaced by benthic preys, such as ephemeropteran larvae.Discussion. The relative proportions of prey with different ecological traits, and dietary variability within and between areas of occurrence, suggest that X. laevis is a generalist predator in both native and invasive populations. Shifts in the realized trophic niche are observed, and appear related to resource availability. Xenopus laevis may strongly impact aquatic ecosystems because of its near complete aquatic lifestyle and its significant consumption of key taxa for the trophic relationships in ponds.
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DOI : 10.7717/peerj.3250
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Do benthic invertebrates use hyporheic refuges during streambed drying? A manipulative field experiment in nested hyporheic flowpaths
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Chafik Maazouzi, D. Galassi, Cécile Claret, Bernard Cellot, F. Fiers, Dominique Martin, Pierre Marmonier, Marie-José Dole-Olivier
article
Ecohydrology, 2017, 10 (6), pp.e1865. ⟨10.1002/eco.1865⟩
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The existence of resilience mechanisms related to a disturbance, such as invertebrate migrations into the hyporheic zone (HZ, saturated subsurface interstices), promotes persistence of benthic communities in river ecosystems. Water exchanges through the HZ, which influence the distribution of biota, are heterogeneous at different scales, determining nested hyporheic flowpaths. The effect of these nested exchanges on the use of the hyporheic refuges by benthic invertebrates is still unknown. We simulated streambed drying in a stream section where hydrological exchanges were considered at riffle (upstream or downstream of riffles) and floodplain (downstream end of a floodplain) scales. Physicochemical indicators determined that local hyporheic flowpaths (up-and downwelling zones) were nested in a large-scale downwelling section of the river. In this situation, the effect of 24 h of experimental drying on the distribution of invertebrates was examined at three sediment depths to follow their migrations into the HZ. Whereas invertebrate assemblages did not change in the control channel, abundance of benthic invertebrate increased in the HZ of the impact channel (up to seven-fold). Changes occurred rapidly (15-24 h) and only upstream of riffle where surface water down-welled. The migration was taxon-specific and concerned the most abundant benthic taxa that temporarily colonize the HZ (''temporary hyporheos,'' e.g., Leuctra cf. fusca, Baetis sp., Caenis sp., Orthocladiinae, Tanypodinae). In the context of climate change, hyporheic refuge use will promote persistence of communities facing the increasing frequency of extreme hydrological events. Improved knowledge about the distribution and function of these refuges is becoming crucial for river managers.
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DOI : 10.1002/eco.1865
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Cytochrome c oxidase barcodes for aquatic oligochaete identification: development of a Swiss reference database
auteur
Régis Vivien, Maria Holzmann, Inge Werner, Jan Pawlowski, Michel Lafont, Benoît J.D. Ferrari
article
PeerJ, 2017, 5:e4122, pp.1-16. ⟨10.7717/peerj.4122⟩
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Introduction. Aquatic oligochaetes represent valuable indicators of the quality of sediments of watercourses and lakes, but their difficult identification based on mor- phological criteria compromises their more common use for eco-diagnostic analyses. This issue could be overcome by using DNA barcodes for species identification. A 10% threshold of cytochrome c oxidase (COI) divergence was proposed for differentiating between oligochaete species based on molecular and morphological data. A Swiss database of COI sequences of aquatic oligochaetes was initiated in 2012. The aim of this study is to complement the Swiss oligochaete database of COI sequences and to confirm the relevance of this threshold for species delimitation. Methods. We sequenced the COI sequence of 216 specimens collected in different regions of Switzerland and ITS2 region of some lineages whose delimitation with COI data was doubtful. Results. We distinguished 53 lineages, among which 34 were new for Switzerland and 17 sequenced for the first time. All the lineages were separated by more than 10% of COI variation, with the exception of some species within Nais and Uncinais. In these two genera, the threshold was lowered to 8% to be congruent with the morphological analysis. The total number of lineages reported so far for Switzerland is 75, including 59 morphospecies or unidentified species and 16 cryptic species. Discussion. Our study shows that the threshold of 10% of COI divergence is generally appropriate to distinguish aquatic oligochaete lineages, but that it must be adjusted for some species. The database reported here will be complemented in the future in parallel to the development of genetic oligochaete indices.
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DOI : 10.7717/peerj.4122
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An integrative approach to assess ecological risks of surface water contamination for fish populations
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Raphaël Santos, Aude Joyeux, Aurélien Besnard, Christophe Blanchard, Cédric Halkett, Sylvie Bony, Wilfried Sanchez, Alain Devaux
article
Environmental Pollution, 2017, 220, pp.588-596. ⟨10.1016/j.envpol.2016.10.007⟩
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Contamination of aquatic ecosystems is considered as one of the main threats to global freshwater biodiversity. Within the European Water Framework Directive (EU-WFD) a particular attention is dedicated to assess ecological risks of surface water contamination and mitigation of chemical pressures on aquatic ecosystems. In this work, we evaluated ecological risks of surface water contamination for fish populations in four EU-WFD rivers through an integrative approach investigating three Lines of Evidence (chemical contamination, biomarker responses as early warning signals of contamination impacting individuals and ecological analyses as an indicator of fish community disturbances). This work illustrates through 4 case studies the complementary role of biomarkers, chemical and ecological analyses which, used in combination, provide fundamental information to understand impacts of chemical pressures that can affect fish population dynamics. We discuss the limitations of this approach and future improvements needed within the EU-WFD to assess ecological risk of river contamination for fish populations.
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DOI : 10.1016/j.envpol.2016.10.007
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Genetic and morphological discrimination of three species of ninespined stickleback Pungitius spp. (Teleostei, Gasterosteidae) in France with the revalidation of Pungitius vulgaris (Mauduyt, 1848)
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Gaël Denys, Henri Persat, Agnès Dettaï, Matthias F. Geiger, Jörg Freyhof, Justine Fesquet, Philippe Keith
article
Journal of Zoological Systematics and Evolutionary Research, 2017, pp.1-25. ⟨10.1111/jzs.12178⟩
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The taxonomy of French ninespined sticklebacks (Pungitius spp.) has long been controver- sial. To clarify the taxonomy in this group, we use mitochondrial (COI) and nuclear (RNF213) sequence markers, as well as morphological data. In France, both genetic mark- ers discriminate three evolutionary lineages. Morphological analysis on fresh and type specimens supports the different lineages and the existence of three species in France. Pungitius pungitius, occurring in the North of France and Rhone basin, is characterized by specimens longer than 35 mm SL, by a flat head with a straight or slightly concave snout, typically 9–10 dorsal spines, 10–11 dorsal soft rays, 9–10 anal soft rays, 0–12 scutes on the caudal peduncle with a keel reaching the last anal-fin ray, longer pelvic fin, post-dor- sal and caudal peduncle lengths, and a slim caudal peduncle (caudal peduncle depth/ length 11.8%–21.9%). Pungitius laevis, occurring in France, in the English Channel basins and Loire drainage, differs from the other species by a head rounded with concave snout in specimens longer than 35 mm SL, accentuating the impression of fleshy lips, 0–4 scutes on the caudal peduncle and a higher caudal peduncle depth/length ratio (15.7%– 34.5%). Finally, Pungitius vulgaris, endemic to the Vienne River and rivers of south-wes- tern France as far north as the Garonne estuary, is differentiated by a rounded head with a straight or slightly convex snout, the absence of scutes on the caudal peduncle and by having 11 pectoral-fin rays. Our data confirm the existence of a hybridization zone in the North of France between P. pungitius and P. laevis. As a result, Pungitius lotharingus is invalid, as it was described based on hybrid specimens. A lectotype for P. laevis was des- ignated because the syntypes included hybrids. This revision provides new perspectives for evolutionary biology studies and will have consequences for Pungitius conservation in France.
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DOI : 10.1111/jzs.12178
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Paternal contribution to development: Sperm genetic damage and repair in fish
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María Paz Herráez, Juan Ausió, Alain Devaux, Silvia González-Rojo, Cristina Fernández-Díez, Sylvie Bony, Núria Saperas, Vanesa Robles
article
Aquaculture, 2017, 472, pp.45-59. ⟨10.1016/j.aquaculture.2016.03.007⟩
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In this reviewwe provide an overviewof the components of the spermatozoa playing an important role in reproductive success beyond fertilization, showing the relationship between the integrity of the diverse elements and the development of a healthy offspring. The present knowledge about fish spermchromatin organization, epigeneticmodifications of DNA and histones and sperm-borne RNAs, essential in controlling embryo development, is summarized, pointing out the possibility of using specific genes or transcripts as biomarkers of sperm quality. Data about commercial species are reported when available and more detailed information about zebrafish sperm is presented. Considering the implications that the integrity of sperm genome and epigenome has on the preservation of a proper genotype and phenotype in the progeny, the methods applied for the study of chromatin damage and for the study of transcriptome are described.Moreover we discuss some injuring agents affecting paternal information, from the presence of contaminants in the aquatic environment, to the reproductive practices applied in fish farming. The consequences of fertilizing with damaged spermatozoa, as well as the zygotic ability to repair damage are also reviewed. Statement of relevance: Role of the sperm on achieving high rates of healthy fries.
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DOI : 10.1016/j.aquaculture.2016.03.007
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Within outlying mean indexes: refining the OMI analysis for the realized niche decomposition
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Stéphane Karasiewicz, Sylvain Dolédec, Sébastien Lefebvre
article
PeerJ, 2017, 5 (e3364), pp.1-17. ⟨10.7717/peerj.3364⟩
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The ecological niche concept has regained interest under environmental change (e.g., climate change, eutrophication, and habitat destruction), especially to study the impacts on niche shift and conservatism. Here, we propose the within outlying mean indexes (WitOMI), which refine the outlying mean index (OMI) analysis by using its properties in combination with the K-select analysis species marginality decomposition. The purpose is to decompose the ecological niche into subniches associated with the experimental design, i.e., taking into account temporal and/or spatial subsets. WitOMI emphasize the habitat conditions that contribute (1) to the definition of species’ niches using all available conditions and, at the same time, (2) to the delineation of species’ subniches according to given subsets of datesor sites. The latter aspect allows addressing niche dynamics by highlighting the influence of atypical habitat conditions on species at a given time and/or space. Then, (3) the biological constraint exerted on the species subniche becomes observable within Euclidean space as the difference between the existing fundamental subniche and the realized subniche. We illustrate the decomposition of published OMI analyses, using spatial and temporal examples. The species assemblage’s subniches are comparable to the same environmental gradient, producing a more accurate and precise description of the assemblage niche distribution under environmental change. The WitOMI calculations are available in the open-access R package “subniche.”
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DOI : 10.7717/peerj.3364
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Females trade off the uncertainty of breeding resource suitability with male quality during mate choice in an anuran
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Hugo Cayuela, Thierry Lengagne, Pierre Joly, Jean-Paul Léna
article
Animal Behaviour, 2017, 123, pp.179-185. ⟨10.1016/j.anbehav.2016.11.002⟩
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In many species, females may be particularly selective about the expected direct benefits of choosing a potential mate or the male's genetic contribution to their offspring. Growing evidence suggests that female choosiness can also be influenced, for instance, by local abiotic factors, the social environment or the presence of heterospecifics. In amphibians that breed in highly temporary ponds with limited trophic resources (such as the yellow-bellied toad, Bombina variegata), competition during larval development may have a strong impact on the fitness of offspring. Accordingly, one might expect females to apply hierarchical decision making, balancing intraspecific competition risks during larval growth against the relative indirect benefits associated with the quality of the male. To investigate this issue, we conducted experiments in seminatural enclosures to test whether the preference of yellow-bellied toad females for good call attractiveness (determined by fundamental frequency) is affected by the risk of larval competition within the pond occupied by the callers. Overall, our results showed that females have a preference for low-frequency calls when prior information does not enable them to assess the relative quality of ponds. However, when prior information enables females to unambiguously determine relative pond quality, females appear to apply hierarchical decision making in which the quality of a pond prevails over call cues related to the quality of the male.
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DOI : 10.1016/j.anbehav.2016.11.002
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The ‘male escape hypothesis’ : sex-biased metamorphosis in response to climatic drivers in a facultatively paedomorphic amphibian.
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Anthony G.E. Mathiron, Jean-Paul Léna, Sarah Baouch, Mathieu Denoël
article
Proceedings of the Royal Society B: Biological Sciences, 2017, 284 (20170176), pp.1-7. ⟨10.1098/rspb.2017.0176⟩
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Paedomorphosis is a major evolutionary process that bypasses metamorpho- sis and allows reproduction in larvae. In newts and salamanders, it can be facultative with paedomorphs retaining gills and metamorphs dispersing. The evolution of these developmental processes is thought to have been driven by the costs and benefits of inhabiting aquatic versus terrestrial habi- tats. In this context, we aimed at testing the hypothesis that climatic drivers affect phenotypic transition and the difference across sexes because sex-ratio is biased in natural populations. Through a replicated laboratory experiment, we showed that paedomorphic palmate newts (Lissotriton helveticus) meta- morphosed at a higher frequency when water availability decreased and metamorphosed earlier when temperature increased in these conditions. All responses were sex-biased, and males were more prone to change pheno- type than females. Our work shows how climatic variables can affect facultative paedomorphosis and support theoretical models predicting life on land instead of in water. Moreover, because males metamorphose and leave water more often and earlier than females, these results, for the first time, give an experimental explanation for the rarity of male paedomor- phosis (the ‘male escape hypothesis’) and suggest the importance of sex in the evolution of paedomorphosis versus metamorphosis.
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DOI : 10.1098/rspb.2017.0176
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How to measure mitochondrial function in birds using red blood cells: a case study in the king penguin and perspectives in ecology and evolution
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Antoine Stier, Caroline Romestaing, Quentin Schull, Emilie Lefol, Jean-Patrice Robin, Damien Roussel, Pierre Bize
article
Methods in Ecology and Evolution, 2017, 8 (10), ⟨10.1111/2041-210X.12724⟩
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Mitochondria are the powerhouse of animal cells. They produce through oxidative phosphorylation more than 90% of the cellular energy (ATP) required for organism's growth, reproduction, and maintenance. Hence, information on mitochondrial function is expected to bring important insights in animal ecology and evolution. Unfortunately, the invasiveness of the procedures required to measure mitochondrial function (e.g. sampling of liver or muscles) has limited its study in wild vertebrate populations so far. Here, we capitalize on the fact that bird red blood cells (RBCs) possess functional mitochondria to describe a minimally invasive approach to study mitochondrial function, using blood samples. In the king penguin, we present a protocol, using a high-resolution respirometry system and specific agonists and antagonists enabling the assessment of mitochondrial function in RBCs. We evaluated the inter-assay repeatability of our measures of mitochondrial function, and tested the influence of sample storage and bird handling time on these measures. We also compared measures of mitochondrial function in RBCs and in the pectoral muscle obtained from the same individuals. Mitochondria from RBCs showed the expected responses to mitochondrial agonists and antagonists, and therefore the protocol presented allows computing effective measures of mitochondrial function. The different measures of RBC mitochondrial function were significantly repeatable, were not affected by the handling time of the bird prior to blood sampling (i.e. stress response), and only minimally affected by the storage time of the sample at 4 °C up to 24 h. Most notably, we showed that mitochondrial parameters measured in RBCs moderately correlated to those measured in the pectoral muscle. This study sheds light on the use of RBCs in birds as a valuable and minimally invasive source of information on mitochondrial function. This approach opens new opportunities to study mitochondrial function in free-living animals and could bring knowledge gains in ecology and evolution. Fish, amphibians and reptiles also possess mitochondria in their RBCs, and the approach presented here could also be applicable to these taxa.
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DOI : 10.1111/2041-210X.12724
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Environmental stressors as a driver of the trait composition of benthic macroinvertebrate assemblages in polluted Iberian rivers
auteur
Maja Kuzmanovic, Sylvain Dolédec, Nuria de Castro-Catala, Antoni Ginebreda, Sergi Sabater, Isabel Munoz, Damia Barcelo
article
Environmental Research, 2017, 156, pp.485-493. ⟨10.1016/j.envres.2017.03.054⟩
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We used the trait composition of macroinvertebrate communities to identify the effects of pesticides and multiple stressors associated with urban land use at different sites of four rivers in Spain. Several physical and chemical stressors (high metal pollution, nutrients, elevated temperature and flow alterations) affected the urban sites. The occurrence of multiple stressors influenced aquatic assemblages at 50% of the sites. We hypothesized that the trait composition of macroinvertebrate assemblages would reflect the strategies that the assemblages used to cope with the respective environmental stressors. We used RLQ and fourth corner analysis to address the relationship between stressors and the trait composition of benthic macroinvertebrates. We found a statistically significant relationship between the trait composition and the exposure of assemblages to environmental stressors. The first RLQ dimension, which explained most of the variability, clearly separated sites according to the stressors. Urban-related stressors selected taxa that were mainly plurivoltine and fed on deposits. In contrast, pesticide impacted sites selected taxa with high levels of egg protection (better egg survival), indicating a potentially higher risk for egg mortality. Moreover, the trait diversity of assemblages at urban sites was low compared to that observed in pesticide impacted sites, suggesting the homogenization of assemblages in urban areas.
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DOI
DOI : 10.1016/j.envres.2017.03.054
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titre
Life and works of Augustin Augier de Favas (1758–1825), author of “Arbre botanique” (1801)
auteur
Nils Hellström, Gilles André, Marc Philippe
article
Archives of natural history, 2017, 44 (1), pp.43-62. ⟨10.3366/anh.2017.0413⟩
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Augustin Augier's “Arbre botanique” (“botanical tree”) (1801), a diagram representing the natural order of plants in the shape of a family tree, is today a standard reference in histories of systematics and phylogenetic trees. The previously unidentified author was a nobleman from Saint-Tropez, a schoolteacher and a priest in the Société de l'Oratoire de Jésus et de Marie immaculée. His biography and two previously unnoticed publications, as well as his correspondence with the Institut national in Paris, are discussed. Knowledge of Augier's identity, his life and works sheds new light upon his taxonomic theories, and helps us to understand his “Arbre botanique”. Long before the tree was made into an icon of evolutionism, Augier used it to demonstrate the beauty and perfect order of divine creation.
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DOI : 10.3366/anh.2017.0413
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Review on fire effects on ectomycorrhizal symbiosis, an unachieved work for a scalding topic
auteur
Adrien Taudière, Richard Franck, Christopher Carcaillet
article
Forest Ecology and Management, 2017, 391, pp.446-457. ⟨10.1016/j.foreco.2017.02.043⟩
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Millions of hectares of ectomycorrhizal (ECM) forests provide most of the wood resource in the northern hemisphere. Among these forests, those that are fire-prone concentrate an astonishing diversity of mutu- alistic soil fungi that are pivotal for seedling establishment, tree growth and forest functioning and dynamics. Here, we review the effects of fire on ECM symbiosis in these forests using a systematic screen- ing of the literature. We reveal that a low number of field studies (73) directly address fire effect on ECM symbiosis, in a restricted geographic area that partially represents the geography of ECM biodiversity stakes and fire risk. The analyzed literature consensually reports long-term shifts in the composition of ECM fungal communities after fire. Contrastingly, the effects of fire on fungal diversity and richness at the local scale continue to be debated among researchers, and need to be documented further using ade- quate experimental device to limit the effects of some identified methodological biases. Furthermore, our analysis emphasizes the urgent need to carefully consider the belowground effects of prescribed burning. This is an important conclusion because this widely implemented and efficient management tool to pre- vent wildfires may impact ECM soil communities in the same way as uncontrolled events. Our analysis finally highlights the need of refining the concept of post-fire ECM fungi, by taking advantage of promis- ing tools, such as next-generation sequencing and quantitative PCR applied to mycelia and spores, to inte- grate the vegetative traits of fungi in integrative definitions.
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DOI : 10.1016/j.foreco.2017.02.043
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Evaluating interspecific niche overlaps in environmental and geographic spaces to assess the value of umbrella species
auteur
Yoan Fourcade, Aurélien G. Besnard, Jean Secondi
article
Journal of Avian Biology, 2017, 48, pp.1-19. ⟨10.1111/jav.01153⟩
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The concept of umbrella species assumes that concentrating resources on the protection of a single species contributes to the conservation of a suite of species and ecological processes belonging to the same ecosystem. The environmental require- ments and geographical distribution of the umbrella species should thus overlap those of the group of targeted species. In western France, the conservation of several large grassland floodplains relies on agri-environmental schemes targeting one single bird species, the corncrake Crex crex. It is considered as an umbrella species but no real assessment of its effec- tiveness has been carried out so far. We used a two-step methodology to assess the potential of the corncrake to act as an umbrella species by estimating niche overlap in the environmental and geographic space between the main ground-nesting species of the bird community in these grasslands, including the corncrake and four passerines. The five species showed substantial differences in their ecological niches so that their distributions did not perfectly overlap. Overlaps in predicted distributions between pairs of species depended on the threshold used to convert suitability to binary maps. Moreover, the number of species that could be protected by a candidate umbrella species was affected by the overlap criterion of success. Although the corncrake may be used as an umbrella species, it would be outperformed by several passerine species. Our study highlights the potential of using niche overlap to select umbrella species. It also reveals the importance of analysing the sensitivity of outputs when changing thresholds and overlap criteria.
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DOI : 10.1111/jav.01153
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Biogeographical Complements for Seligeria carniolica and S. irrigata (Bryophyta, Seligeriaceae)
auteur
Marc Philippe, Ryszard Ochyra
article
Cryptogamie Bryologie, 2017, 38 (3), pp.303-312. ⟨10.7872/cryb/v38.iss3.2017.303⟩
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New distributional data from France for two European endemic species, Seligeria carniolica and S. irrigata, are provided. The latter is new to France and this discovery significantly extends its current geographical range. The former is red-listed as an endangered endemic species in Europe and for a long time it was known only from some widely distributed isolated localities but nowadays it appears to be quite well represented in eastern France. The biogeography of these two species is discussed and S. carniolica, formerly considered as a boreal-montane suboceanic element, could be better designated as a Perialpine species with disjunct, highly isolated occurrences in northern Europe and in the Balkan Peninsula. Seligeria irrigata is primarily an Alpine species with some isolated localities in the Western Carpathians of Slovakia and in the Abruzzean Apennine Mountains in Italy.
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DOI : 10.7872/cryb/v38.iss3.2017.303
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d18O-Derived incubation temperatures of oviraptorosaur eggs.
auteur
Romain Amiot, Xu Wang, Shuo Wang, Christophe Lécuyer, Jean-Michel Mazin, Jinyou Mo, Jean-Pierre Flandrois, François Fourel
article
Palaeontology, 2017, pp.1-15. ⟨10.1111/pala.12311⟩
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In order to determine the incubation temperature of eggs laid by non-avian dinosaurs, we analysed the oxygen iso- tope compositions of both eggshell carbonate (d18Oc) and embryo bone phosphate (d18Op) from seven oviraptorosaur eggs with preserved in ovo embryo bones. These eggs come from the Upper Cretaceous Nanxiong Formation of Jiangxi Pro- vince, China. Oviraptorosaur theropods were selected because of their known brooding behaviour as evidenced by preserved adult specimens fossilized in brooding posture on their clutch. Incubation temperature of these embryos was estimated based on the following considerations: eggshell d18Oc value reflects the oxygen isotope composition of egg water fluid; embryo bones precipitate from the same egg fluid; and oxygen isotope fractionation between phosphate and water is controlled by the egg temperature. A time-dependent model predicting the d18Op evolution of the embryo skeleton during incubation as a function of egg temperature was built, and measured d18Oc and d18Op values used as boundary conditions. According to the model outputs, oviraptorosaurs incubated their eggs within a 35–40°C range, similar to extant birds and compatible with the known active brooding behaviour of these theropod dinosaurs. Provided that both eggshell and embryo bones preserved their original oxygen isotope compositions, this method could be extended to investigate some reproductive traits of other extinct groups of oviparous amniotes.
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DOI : 10.1111/pala.12311
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Relatedness predicts male mating success in a pond-breeding amphibian
auteur
Hugo Cayuela, Jean-Paul Léna, Thierry Lengagne, Bernard Kaufmann, Nathalie Mondy, Lara Konecny, Adeline Dumet, Antonin Vienney, Pierre Joly
article
Animal Behaviour, 2017, 130, pp.251-261. ⟨10.1016/j.anbehav.2017.05.028⟩
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When deciding to mate, it is assumed that females choose males bearing genes that will improve the genetic quality of their offspring, which is affected by both additive and nonadditive genetic variation. In this context, a ‘compatible genes’ model has been put forward to explain female mating decisions. According to this model, females are assumed to increase the genetic quality of their offspring by choosing mates on the basis of interactions between maternal and paternal genomes. Yet, this model is mainly supported by empirical data in endotherm vertebrates. Few studies have investigated this issue in terrestrial ectotherms like amphibians. These organisms often live in spatially structured populations characterized by small subpopulations and a high degree of philopatry, leading to striking reduction in gene flow, high genetic drift and relatively high inbreeding levels. In such a situation, one might expect that natural selection should favour mating tactics limiting the risk of inbreeding depression. In this paper, using an experimental approach controlling for the reproductive state of males, we examined how genetic compatibility may affect mating behaviour in an anuran, the yellow-bellied toad, Bombina variegata. First, our analyses confirmed a high degree of inbreeding in the studied population. Yet, we did not find any mating tactic that reduced the risk of inbreeding depression. Contrary to our expectations, males more closely related to the female had the higher mating success. We discuss the ecological and evolutionary implications of these results.
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DOI : 10.1016/j.anbehav.2017.05.028
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Trade-offs between growth and defence in two phylogenetically close invasive species
auteur
Gabrielle Thiébaut, Anatole Boiché, Damien Lemoine, Marie-Hélène Barrat-Segretain, Damien G. Lemoine
article
Aquatic Ecology, 2017, 51 (3), pp.405-415. ⟨10.1007/s10452-017-9625-4⟩
resume
The success of an invasive plant species could be explained by trade-off between growth and defence. The aim of this paper was to explore the responses of two non-native aquatic macrophytes Elodea canadensis and Elodea nuttallii to herbivores in their introduced range. We assessed the palatability of the two phylogenetically close aquatic plant species in field and their responses to gammarid consumption in spring, summer and autumn in a microcosm experiment. We measured the variation of functional traits for each season. The traits selected were those judged most closely related to the allocation of resources to growth or to resistance against herbivores. We clearly established that the strategies of the two species were different and that their consumption rate differed in summer. In summer, E. canadensis allocated more of its resources to structural defence (leaf toughness). The increase in leaf thickness reduced the palatability of E. canadensis, whereas E. nuttallii stimulated its growth. Moreover, a decrease in dry matter content in E. nuttallii was found during the growing season in field. In autumn, both plant species accumulated nitrogen and phosphorus in their tissues. We also demonstrated that neither species induced efficient chemical defences against the herbivores. The different strategies of these two Elodea species could be explained by their different resident times in the introduced area and by an adaptation of the naturalised E. canadensis to herbivores.
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DOI : 10.1007/s10452-017-9625-4
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Doping for sex: Bad for mitochondrial performances? Case of testosterone supplemented Hyla arborea during the courtship period
auteur
Julia L. Desprat, Loïc Teulier, Sara Puijalon, Adeline Dumet, Caroline Romestaing, Glenn J. Tattersall, Thierry Lengagne, Nathalie Mondy
article
Comparative Biochemistry and Physiology - A: Comparative Physiology, 2017, 209, pp.74-83. ⟨10.1016/j.cbpa.2017.04.021⟩
resume
Sexual selection has been widely explored from numerous perspectives, including behavior, ecology, and to a lesser extent, energetics. Hormones, and specifically androgens such as testosterone, are known to trigger sexual behaviors. Their effects are therefore of interest during the breeding period. Our work investigates the effect of testosterone on the relationship between cellular bioenergetics and contractile properties of two skeletal muscles involved in sexual selection in tree frogs. Calling and locomotor abilities are considered evidence of good condition in Hyla males, and thus server as proxies for male quality and attractiveness. Therefore, how these behaviors are powered efficiently remains of both physiological and behavioral interest. Most previous research, however, has focused primarily on biomechanics, contractile properties or mitochondrial enzyme activities. Some have tried to establish a relationship between those parameters but to our knowledge, there is no study examining muscle fiber bioenergetics in Hyla arborea. Using chronic testosterone supplementation and through an integrative study combining fiber bioenergetics and contractile properties, we compared sexually dimorphic trunk muscles directly linked to chronic sound production to a hindlimb muscle (i.e. gastrocnemius) that is particularly adapted for explosive movement. As expected, trunk muscle bioenergetics were more affected by testosterone than gastrocnemius muscle. Our study also underlines contrasted energetic capacities between muscles, in line with contractile properties of these two different muscle phenotypes. The discrepancy of both substrate utilization and contractile properties is consistent with the specific role of each muscle and our results are elucidating another integrative example of a muscle force-endurance trade-off.
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DOI
DOI : 10.1016/j.cbpa.2017.04.021
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titre
Water infiltration in an aquifer recharge basin affected by temperature and air entrapment
auteur
Sebastien Loizeau, Yvan Rossier, Jean-Paul Gaudet, Aurore Refloch, Katia Besnard, Rafaël Angulo-Jaramillo, Laurent Lassabatère
article
Journal of Hydrology and Hydromechanics, 2017, 65 (3), pp.222-233. ⟨10.1515/johh-2017-0010⟩
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Artificial basins are used to recharge groundwater and protect water pumping fields. In these basins, infiltration rates are monitored to detect any decrease in water infiltration in relation with clogging. However, miss-estimations of infiltration rate may result from neglecting the effects of water temperature change and air-entrapment. This study aims to investigate the effect of temperature and air entrapment on water infiltration at the basin scale by conducting successive infiltration cycles in an experimental basin of 11869 m(2) in a pumping field at Crepieux-Charmy (Lyon, France). A first experiment, conducted in summer 2011, showed a strong increase in infiltration rate; which was linked to a potential increase in ground water temperature or a potential dissolution of air entrapped at the beginning of the infiltration. A second experiment was conducted in summer, to inject cold water instead of warm water, and also revealed an increase in infiltration rate. This increase was linked to air dissolution in the soil. A final experiment was conducted in spring with no temperature contrast and no entrapped air (soil initially water-saturated), revealing a constant infiltration rate. Modeling and analysis of experiments revealed that air entrapment and cold water temperature in the soil could substantially reduce infiltration rate over the first infiltration cycles, with respective effects of similar magnitude. Clearly, both water temperature change and air entrapment must be considered for an accurate assessment of the infiltration rate in basins.
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DOI : 10.1515/johh-2017-0010
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titre
Thematic Issue on Soil Water Infiltration
auteur
Massimo Iovino, Rafaël Angulo-Jaramillo, Vincenzo Bagarello, Horst Gerke, Jay Jabro, Laurent Lassabatère
article
Journal of Hydrology and Hydromechanics, 2017, 65 (3), pp.205-208. ⟨10.1515/johh-2017-0036⟩
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DOI : 10.1515/johh-2017-0036
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titre
Using microwave soil heating to inhibit invasive species seed germination
auteur
Mélissa de Wilde, Elise Buisson, Nicole Yavercovski, Loic Willm, Livia Bieder, Francois Mesleard, Mélissa de Wilde, François Mesléard
article
Invasive Plant Science and Management, 2017, 10 (3), pp.262-270. ⟨10.1017/inp.2017.29⟩
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Successful invasive plant eradication is rare, because the methods used target the adult stage, not taking into account the development capacity of a large seedbank. Heating by microwave was considered, because it offers a means to quickly reach the temperature required for loss of seed viability and inhibition of germination. Previous results were not encouraging, because homogeneous and deep-wave penetration was not achieved, and the various parameters that can affect treatment effectiveness were incompletely addressed. This study aimed to determine, under experimental conditions, the best microwave treatment to inhibit invasive species seed germination in terms of power (2, 4, 6 kW) and duration (2, 4, 8 min) of treatments and depending on soil moisture (10%, 13%, 20%, 30%) and seed burial depth (2, 12 cm). Three invasive species were tested: Bohemian knotweed, giant goldenrod, and jimsonweed. The most effective treatments required relatively high power and duration (2kW8min, 4kW4min, 6kW2min, and 6kW4min; 4kW8min and 6kW8min were not tested for technical reasons), and their effectiveness diminished with increasing soil moisture with germination percentage between 0% and 2% for the lowest soil moisture, 0% and 56% for intermediate soil moisture, and 27% and 68% in control treatments. For the highest soil moisture, only 2kW8min and 4kW4min reduced germination percentage between 2% and 19%. Occasionally, germination of seeds located at the 12-cm depth was more strongly affected. Giant goldenrod seeds were the most sensitive, probably due to their small size. Results are promising and justify further experiments before developing a field microwave device to treat large volumes of soil infested by invasive seed efficiently and with reasonable energy requirements. Other types of soil, in terms of texture and organic matter content, should be tested in future experiments, because these factors influence soil water content and, consequently, microwave heating.
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DOI : 10.1017/inp.2017.29
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Uncoupling effect of palmitate is exacerbated in skeletal muscle mitochondria of sea-acclimatized king penguins (Aptenodytes patagonicus)
auteur
Benjamin Rey, Claude H. B. Duchamp, Damien Roussel
article
Comparative Biochemistry and Physiology - Part A: Molecular and Integrative Physiology, 2017, 211, pp.56-60. ⟨10.1016/j.cbpa.2017.06.009⟩
resume
In king penguin juveniles, the environmental transition from a terrestrial to a marine habitat, occurring at fledging, drastically stimulates lipid catabolism and the remodelling of muscle mitochondria to sustain extensive swimming activity and thermoregulation in the cold circumpolar oceans. However, the exact nature of these mechanisms remains only partially resolved. Here we investigated, in vitro, the uncoupling effect of increasing doses of fatty acids in pectoralis muscle intermyofibrillar mitochondria isolated, either from terrestrial never-immersed or experimentally cold water immersed pre-fledging king penguins or from sea-acclimatized fledged penguins. Mitochondria exhibited much greater palmitate-induced uncoupling respiration and higher maximal oxidative capacity after acclimatization to marine life. Such effects were not reproduced experimentally after repeated immersions in cold water, suggesting that the plasticity of mitochondrial characteristics may not be primarily driven by cold exposure per se but by other aspects of sea acclimatization. Keywords
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DOI : 10.1016/j.cbpa.2017.06.009
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Field-based assessment of the mechanism of maize yield enhancement by Azospirillum lipoferum CRT1
auteur
Camille Rozier, Jihane Hamzaoui, Damien Lemoine, Sonia Czarnes, Laurent Legendre
article
Scientific Reports, 2017, 7 (7416), pp.1-12. ⟨10.1038/s41598-017-07929-8⟩
resume
Plant Growth-Promoting Bacteria (PGPB) of the genus Azospirillum are known to enhance root growth and yield in many plant species including cereals. To probe the underlying mechanisms, correlations between modifications of yield and 6-leaf plantlet characteristics were estimated on maize in four fields with contrasting soil properties over two consecutive years using the commercial isolate A. lipoferum CRT1. In both years, plantlet metabolome, photosynthetic potential and organ morphology were found to display field-and inoculation-specific signatures. Metabolomic analyses revealed that A. lipoferum CRT1 mostly affected sugar metabolism with no suggested impact on N and P assimilation. Mineral nitrogen feeding increased yield but did not affect yield enhancement by the bacterial partner. However, greater improvements of leaf photosynthetic potential correlated with yield diminutions and larger plantlets in all of their proportions correlated with yield enhancements. Bacterial inoculation restored proper seed-to-adult plant ratio when it accidentally dropped below 80%. Only in these cases did it raise yield. All in all, securing mature plant density is hypothesized as being the primary driver of A. lipoferum CRT1-mediated yield enhancement in maize fields.
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DOI : 10.1038/s41598-017-07929-8
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titre
The palaeolatitudinal distribution of fossil wood genera as a proxy for European Jurassic terrestrial climate
auteur
Marc Philippe, Sara Puijalon, Guillaume C Suan, Sylvain Mousset, Frédéric Thévenard, Emanuela Mattioli
article
Palaeogeography, Palaeoclimatology, Palaeoecology, 2017, 466 (373–381), ⟨10.1016/j.palaeo.2016.11.029⟩
resume
The potential of using the latitudinal distributions of fossil wood genera as a proxy for Jurassic terrestrial climate conditions in western Laurasia was tested using a database of 386 entries. The fossil wood genera Brachyoxylon, Protaxodioxylon and Simplicioxylon are southern taxa, which have only occasionally extended north of 45°N (all latitude references are to palaeolatitudes). Conversely, Protocedroxylon and Xenoxylon are mostly found at high latitudes. The standard deviation of the data on the palaeolatitudes of the northern genera is, however, much larger than that of the southern genera. This is interpreted as resulting from brief periodic southward extensions of the Protocedroxylon and Xenoxylon distributions, while the southern genera remained confined south of 40°N. The interval during which the northern genera replaced the southern genera at mid-latitudes can be hypothesized to be times of global terrestrial climate cooling or increased rainfall. Comparisons between the spatiotemporal distributions of these ‘northern’ taxa and independent climate-sensitive indicators (clay mineral assemblages, oxygen isotopes, and neritic carbonate distribution) suggest that these genera were adapted to more humid conditions characterizing the mid-latitudes of the Northern Hemisphere. Accordingly, southward migrations of this climatic zone occurred during the Early and Late Pliensbachian, Early Toarcian, and Early Middle Oxfordian time intervals. These reconstructions are limited by the low resolution and restricted spatial coverage of the wood record. Therefore, further sampling at the ammonite zone level is needed. Nevertheless, the present study suggests that wood taxa distribution represents an underexploited but potentially powerful record of terrestrial environmental changes during the Jurassic Period.
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DOI : 10.1016/j.palaeo.2016.11.029
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Less effective selection leads to larger genomes
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Tristan Lefébure, Claire Morvan, Florian Malard, Clémentine François, Lara Konecny-Dupré, Laurent Guéguen, Michèle Weiss-Gayet, Andaine Seguin-Orlando, Luca Ermini, Clio Der Sarkissian, N. Pierre Charrier, David Eme, Florian Mermillod-Blondin, L. Duret, Cristina Vieira, Ludovic Orlando, Christophe Jean Douady
article
Genome Research, 2017, 27, pp.1016-1028. ⟨10.1101/gr.212589.116⟩
resume
The evolutionary origin of the striking genome size variations found in eukaryotes remains enigmatic. The effective size of populations, by controlling selection efficacy, is expected to be a key parameter underlying genome size evolution. However, this hypothesis has proved difficult to investigate using empirical datasets. Here, we tested this hypothesis using twenty-two de novo transcriptomes and low-coverage genomes of asellid isopods, which represent eleven independent habitat shifts from surface water to resource-poor groundwater. We show that these habitat shifts are associated with higher transcriptome-wide dN/dS. After ruling out the role of positive selection and pseudogenization, we show that these transcriptome-wide dN/dS increases are the consequence of a reduction in selection efficacy imposed by the smaller effective population size of subterranean species. This reduction is paralleled by an important increase in genome size (25% increase on average), an increase also confirmed in subterranean decapods and mollusks. We also control for an adaptive impact of genome size on life history traits but find no correlation between body size, or growth rate, and genome size. We show instead that the independent increases in genome size measured in subterranean isopods are the direct consequence of increasing invasion rates by repeated elements, which are less efficiently purged out by purifying selection. Contrary to selection efficacy, polymorphism is not correlated to genome size. We propose that recent demographic fluctuations and the difficulty to observe polymorphism variations in polymorphism-poor species can obfuscate the link between effective population size and genome size when polymorphism data is used alone.
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DOI : 10.1101/gr.212589.116
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Habitat-related variation in the plasticity of a UV-sensitive photoreceptor over a small spatial scale in the palmate newt
auteur
Jean Secondi, Mélissa Martin, Delphine Goven, Pascal Mège, Stéphane Sourice, Marc Théry
article
Journal of Evolutionary Biology, 2017, 30 (6), pp.1229-1235. ⟨10.1111/jeb.13076⟩
resume
Plastic phenotypes are expected to be favoured in heterogeneous environments compared with stable environments. Sensory systems are interesting to test this theory because they are costly to produce and support, and strong fitness costs are expected if they are not tuned to the local environment. Consistently, the visual system of several species changes with the conditions experienced during early development. However, there is little information on whether the amplitude of the change, that is the reaction norm, differs between visual environments. Given the rapid change of many ecosystems, especially eutrophication for aquatic habitats, it is crucial to determine down to which spatial scale, change in the reaction norm occurs. We addressed this issue by quantifying the between-habitat variation in the expression of a UV-sensitive opsin in a newt. In western France, this species breeds in ponds of small forest patches, where water filters out UV, and in agricultural ponds where UV transmission is variable. We raised larvae from both habitats with or without exposure to UV. Opsin expression was reduced in larvae from agricultural habitats when raised without UV, whereas it was low in larvae from forest ponds under all lighting conditions. Thus, the variation in the reaction norm of opsin expression was lower in stable filtering environments and higher in heterogeneous environments. Its variation occurred between habitats across a small spatial scale. We discuss the hypotheses for this pattern and for the maintenance of residual opsin expression in forest populations.
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DOI : 10.1111/jeb.13076
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Functional diversity: a review of methodology and current knowledge in freshwater macroinvertebrate research
auteur
Dénes Schmera, Jani Heino, János Podani, Tibor Eros, Sylvain Dolédec
article
Hydrobiologia, 2017, 787, pp.27-44. ⟨10.1007/s10750-016-2974-5⟩
resume
Although several studies have examined the functional diversity of freshwater macroinvertebrates, the variety of methodologies combined with the absence of a synthetic review make our understanding of this field incomplete. Therefore, we reviewed the current methodology for assessing functional diversity in freshwater macroinvertebrate research. Our review showed that most papers quantified functional diversity using biological traits, among which feeding habits were the most common traits probably due to the assumed links between feeding and ecosystem functions. A large number of diversity measures have been applied for quantifying functional diversity of freshwater macroinvertebrate assemblages, among which Rao’s quadratic entropy looks like the most frequent. In most papers, functional diversity was positively related to taxon richness, and functional redundancy was a key concept in explaining this correlation. Most studies detected strong influence of the environmental factors as well as human impact on functional diversity. Finally, our review revealed that functional diversity research is biased towards European running waters and is hindered by yet insufficient information on the autecology of macroinvertebrates.
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DOI
DOI : 10.1007/s10750-016-2974-5
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Gammarus pulex (Crustacea: Amphipoda) avoids increasing water temperature and intraspecific competition through vertical migration into the hyporheic zone: a mesocosm experiment
auteur
Ross Vander Vorste, Florian Mermillod-Blondin, Frédéric Hervant, R. Mons, T. Datry
article
Aquatic Sciences - Research Across Boundaries, 2017, 79 (1), pp.45-55. ⟨10.1007/s00027-016-0478-z⟩
resume
The saturated interstices below and adjacent to the riverbed (i.e., the hyporheic zone) can be a refuge for biota during low flows, flow cessation and river drying. Prior to complete drying, organisms are constrained by abiotic and biotic factors (e.g., water temperature, com- petition) and may respond through vertical migration into the hyporheic zone. However, it remains unclear when temperature and competition become harsh enough to trigger migration. Furthermore, potential consequences of using the hyporheic zone, which is often food-limited, on the survival, effects on ecosystem function and physiology of organisms are unknown. We tested the hypotheses that (1) Gammarus pulex, a widespread detritivore, migrates into the hyporheic zone to avoid increasing surface water temperature and intraspecific competition and (2) that these factors would reduce their survival, leaf mass consumption and energy stores. Using 36 mesocosms, three temperature (15, 20, 25 °C) and species density levels (low, medium, high) were manipulated in a factorial design over 15 days. Increasing temperature to 25 °C and a threefold increase in density both caused G. pulex to vertically migrate, and the interaction of these factors was additive, rather than antagonistic or synergistic. Importantly, survival, leaf consumption and glycogen content were reduced in high temperature and density treatments, suggesting tradeoffs between tolerating harsh surface conditions and limitations of inhabiting the hyporheic zone. Identifying that the hyporheic zone is used by G. pulex to avoid high water temperature and intraspecific competition is a key finding considering the global-scale increases in temperature and flow intermittence.
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DOI
DOI : 10.1007/s00027-016-0478-z
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D/H fractionation during the sublimation of water ice
auteur
Christophe Lécuyer, Aurélien Royer, François Fourel, Magali Seris, Laurent Simon, François Robert
article
Icarus, 2017, 285, pp.1-7. ⟨10.1016/j.icarus.2016.12.015⟩
resume
Experiments of sublimation of pure water ice have been performed in the temperature range −105 °C to −30 °C and atmospheric partial pressures ranging from 10−6 to 10−1 mb. Sampling of both vapour and residual ice fractions has been performed with the use of a vacuum line designed for the extraction and purification of gases before the measurement of their D/H ratios. Sublimation was responsible for sizable isotopic fractionation factors in the range 0.969–1.123 for temperatures lying between −105 °C and −30 °C. The fractionation factor exhibits a cross-over at temperatures around −50 °C with the water vapour fraction being D-depleted relative to the residual ice fraction at T < −50 °C (αice-vapour = 0.969– 0.995). This cross-over has implications for the understanding of the atmospheric water cycle of some terrestrial planets such as the Earth or Mars. The magnitude of deuterium enrichment or depletion be- tween ice and water vapour cannot explain the differences in the D/H ratios amongst Jupiter comets and long–period comets families nor those that have been documented between Earth’s and cometary water
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DOI : 10.1016/j.icarus.2016.12.015
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Spatial and Temporal Stability of Major and Trace Element Leaching in Urban Stormwater Sediments
auteur
Clémentine Drapeau, Cécile Delolme, Vincent Chatain, Mathieu Gautier, Denise Blanc, Mostafa Benzaazoua, Laurent Lassabatère
article
Open Journal of Soil Science, 2017, 07 (11), pp.347-365. ⟨10.4236/ojss.2017.711025⟩
resume
Urban sediment generated by stormwater management techniques are highly contaminated with various trace elements. The characterization of trace element speciation and mobility are critical information to improve environmental risk assessment. This study investigates the spatial and temporal variability of major and trace element release from a sedimentary layer in Django Reinhart stormwater infiltration basin (Chassieu, eastern suburbs of Lyon, France). Sampling was conducted for 3 zones and two dates. Chemical characterization was performed (X-Ray diffraction, ICP-AES). The samples were submitted to Acid Neutralization Capacity & Base Neutralization Capacity ANC-BNC tests, according to European standard 14429 (AFNOR, 2015). Solid matrices were mixed with acid or basic solutions and physicochemical parameters and major and trace element release (i.e. Al, Ca, Fe, P, S, Si, Cu, Zn and total carbon) were followed as a function of pH. The results show that the urban sediment has no significant spatial and temporal variability with regards to element release. This observation is all the more surprising that the samples were collected in three contrasting zones regarding stormwater supply and hydric conditions. Element release follows the same trends as a function of pH with a bell-shaped solubilization curve exhibiting with the highest solubility at extreme pH values. However, the samples showed slight differences concerning the release of major elements. Such differences are related to slight differences in total mineral contents (organic matter, carbonates…) and chemical composition of the sediments. The results show that despite the varying environmental conditions, the sediment chemical properties can be considered as very stable and uniform over space, depending mainly on the local geochemical context and watershed characteristics. This study highlights the strength and affluence of the information obtained by ANC-BNC tests on the release of major and traces metal elements by urban sediments and brings relevant information regarding the management of these sediments.
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DOI : 10.4236/ojss.2017.711025
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Identification and assessment of ecotoxicological hazards attributable to pollutants in urban wet weather discharges
auteur
Antoine Gosset, Claude Durrieu, Frédéric Orias, Rémy Bayard, Yves Perrodin
article
Environ. Sci.: Processes Impacts, 2017, 19, pp.1150-1168. ⟨10.1039/C7EM00159B⟩
resume
The phenomenon of urbanization leads to considerable pressure on urban/suburban aquatic ecosystems. Urban Wet Weather Discharges (UWWDs) during rainfall events are a major source of pollutants leached onto and into urban surfaces and sewers, which in turn affect aquatic ecosystems. The aim of this study is to assess the ecotoxicity of the different compounds identified in UWWDs and identify the hazard represented by each of them. To this end, hazard quotients (HQ) were calculated for each compound detected in UWWDs, based on their Predicted No Effect Concentration (PNEC) values and their maximum concentration (MECmax) found in the dissolved part of UWWDs. For the 207 compounds identified in UWWDs, sufficient data existed for 165 of them to calculate their PNEC. The ecotoxicity of these compounds is greatly variable. Pesticides represent a high proportion of the wide variety of hazardous compounds whose HQ were calculated (a total of 94 HQ), and they are among the most hazardous pollutants (HQ >1000) transported by stormwater. On the contrary, the hazard of Combined Sewer Overflows (CSO) is mainly linked to heavy metals and pharmaceutical compounds. Consequently, the monitoring of these pollutants is a priority in the future. Lastly, it is to bear in mind that the hazard level of certain pollutants could be underestimated, due to their adsorption on particles, leading their low presence in the dissolved phase of UWWDs. So, an in-depth study of these pollutants will be required to clarify their effects on aquatic organisms.
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DOI : 10.1039/C7EM00159B
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Discriminating permanent from temporary rivers with traits of chironomid genera
auteur
Sonia Serra, Manuel A. S. Graça, Sylvain Dolédec, João Feio Maria
article
Annales de Limnologie - International Journal of Limnology, 2017, 53, pp.161-174. ⟨10.1051/limn/2017004⟩
resume
Chironomidae are diverse and present a wide variety of ecological preferences. Thus, they have high potential in establishing reference conditions for river bioassessment and in providing functional information, especially when other macroinvertebrates are poorly represented. However, because of taxo- nomic difficulties and poor knowledge of traits, they are neglected in bioassessment programmes and kept at coarser taxonomic levels, reducing the discrimination power of invertebrate-based diagnostic tools. Here, we compared the efficiency of Chironomidae at the subfamily and genus levels and their biological traits (Eltonian and morphological) in the distinction between permanent (medium altitude and lowland) and temporary Mediterranean streams. We established a priori predictions on the expected Chironomidae trait categories in each stream type, conferring the best adaptations to particular environmental constraints. Genus composition (not subfamily) and respective trait categories differed among the three stream types. Both biological traits identified differences between stream types. Among Eltonian traits, diapause stages seg- regated permanent medium altitude from lowland and temporary stream assemblages, reflecting adaptations to temperature and flow regime variations. Substrate relation and size distinguished temporary from perma- nent stream assemblages, interpreted as an adaptation to unstable sediments and irregular flow regimes. Morphological traits associated with mobility and foraging (e.g., body setae, Lauterborn sensory organs) dis- criminated temporary from permanent stream assemblages, reflecting differences in temporal and spatial stream heterogeneity. The use of these morphological characteristics relying on the observation of few char- acteristics, offers an alternative to the use of Chironomidae Eltonian traits in bioassessment and ecological studies, without a need for high taxonomic expertise.
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DOI : 10.1051/limn/2017004
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Impacts of thinning of a Mediterranean oak forest on soil properties influencing water infiltration
auteur
Simone Di Prima, Vincenzo Bagarello, Rafaël Angulo-Jaramillo, Inmaculada Bautista, Artemi Cerdà, Antonio del Campo, María González-Sanchis, Massimo Iovino, Laurent Lassabatère, Federico Maetzke
article
Journal of Hydrology and Hydromechanics, 2017, 65 (3), pp.276-286. ⟨10.1515/johh-2017-0016⟩
resume
In Mediterranean ecosystems, special attention needs to be paid to forest–water relationships due to water scarcity. In this context, Adaptive Forest Management (AFM) has the objective to establish how forest resources have to be managed with regards to the efficient use of water, which needs maintaining healthy soil properties even after disturbance. The main objective of this investigation was to understand the effect of one of the AFM methods, namely forest thinning, on soil hydraulic properties. At this aim, soil hydraulic characterization was performed on two contiguous Mediterranean oak forest plots, one of them thinned to reduce the forest density from 861 to 414 tree per ha. Three years after the intervention, thinning had not affected soil water permeability of the studied plots. Both ponding and tension infiltration runs yielded not significantly different saturated, Ks, and unsaturated, K–20, hydraulic conductivity values at the thinned and control plots. Therefore, thinning had no an adverse effect on vertical water fluxes at the soil surface. Mean Ks values estimated with the ponded ring infiltrometer were two orders of magnitude higher than K–20 values estimated with the minidisk infiltrometer, revealing probably soil structure with macropores and fractures . The input of hydrophobic organic matter, as a consequence of the addition of plant residues after the thinning treatment, resulted in slight differences in terms of both water drop penetration time, WDPT, and the index of water repellency, R, between thinned and control plots. Soil water repellency only affected unsaturated soil hydraulic conductivity measurements. Moreover, K–20 values showed a negative correlation with both WDPT and R, whereas Ks values did not, revealing that the soil hydrophobic behavior has no impact on saturated hydraulic conductivity.
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DOI : 10.1515/johh-2017-0016
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Cuticle ultrastructure of Pseudofrenelopsis gansuensis: Further taxonomical implications for Cheirolepidiaceae
auteur
Gaëtan Guignard, Xiao-Ju Yang, Yong-Dong Wang
article
Cretaceous Research, 2017, 71, pp.24-39. ⟨10.1016/j.cretres.2016.11.006⟩
resume
A study of the cheirolepidiaceous conifer Pseudofrenelopsis gansuensis from the Lower Cretaceous of Wangqing Jilin Province in China was conducted in detail using scanning and transmission electron microscopy techniques. In total, nine ultrastructural features were recognized for the cuticle of this fossil plant, which are helpful in the distinguishing between cuticles of ordinary epidermal cells, subsidiary cells, guard cells and hypodermal cells of the stomatal apparatus. A three dimensional reconstruction of the cuticle ultrastructure was obtained. Pseudofrenelopsis gansuensis is the second species of this genus for which the cuticle ultrastructure has been statistically examined with 30 measurements and estimated con␣dence interval values. The close comparison of the cuticle ultrastructure characters, including sta- tistical data, among Cheirolepidiaceae and other fossil conifers provides potential evidence of the taxonomic signi␣cance of this genus: ten characters are potentially valuable for speci␣c separation, eleven parameters for generic separation and three parameters seem also to be useful for Family determination. The differences in the chemical composition according to preliminary statistical element analyses of the cuticles based on three ratios in two species of Pseudofrenelopsis, P. dalatzensis and P. gansuensis, should also be examined in future studies.
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DOI : 10.1016/j.cretres.2016.11.006
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Confounding legacies of land uses and land-form pattern on the regional vegetation structure and diversity of Mediterranean montane forests
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Xavier Fortuny, Sandrine Chauchard, Christopher Carcaillet
article
Forest Ecology and Management, 2017, 384, pp.268-278. ⟨10.1016/j.foreco.2016.11.002⟩
resume
Grazing by livestock and logging are among the main widespread forest uses in mountain forests. Centuries of these anthropogenic disturbances have shaped forests in Europe, especially in the Mediterranean region. Since the 19th century, pastoralism and forestry have experienced deep changes. The present study aims to assess and quantify the effects of these changes in forest uses along with environmental variables on forest vegetation structure and diversity in order to disentangle the role of landform versus land uses on ecological diversity in Mediterranean Pyrenees forests. Forest uses history was inferred from historical records and census whereas environmental variables, forest structure and diversity proxies were collected and measured based on 42 plots within 5 forests situated on the French-Spanish boundary. Both variables of environment and forest uses explained forest structure and diversity pattern. The most important part of the forest structure and the diversity pattern were due to the joined effect of forest uses, environmental and spatial variables. As expected, altitude, slope, temperature and precipitation were the main environmental drivers of forest structures and diversity. Among forest uses, the historical forestry treatment and the historical dominant livestock also strongly controlled the forest structure and diversity. Forest uses and environmental variables are closely related since forest use pattern is constrained by physical features. Covariation among forest uses and environ- mental variables produce confounding effects that make difficult the determination of the exact causal relationships. The contributions of forest uses, environmental and spatial variables were not disentangled due to large covariance between each variable.
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DOI : 10.1016/j.foreco.2016.11.002
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Male within-individual variability in a sexual signal component and its impact on female choice
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Thierry Lengagne, Yann Voituron, Doris Gomez
article
Behavioral Ecology, 2017, 28 (1), pp.108-116. ⟨10.1093/beheco/arw120⟩
resume
A growing body of literature deals with the influence of physical or social environments on signal components over long time peri- ods. Surprisingly, variations of signal quality over minutes or hours are less studied although most of the behavioral decisions of the receiver are taken at this time scale. Despite potentially strong implications on theoretical developments linked to sexual selection and communication, within-individual variability in a signal component and its possible consequence on accuracy of female choice has never been thoroughly investigated. Focusing on call dominant frequency (DF) in the European tree frog, Hyla arborea, we showed that frequency variability is due to a warm-up effect on the beginning of the call sequence but not to an exhaustion effect at the end of the sequence. Nevertheless, the great majority of male within-variability at the night scale is due to sudden discontinuities with independent temporal patterns from one individual to another. Secondly, we simulated female mate choice decisions with simple rules based on DF. Within-individual variability in DF the proportion of beneficial choice decreases up to 30% in the worst case. In addition, to overcome these temporary variations in male signal, we emphasize a weak advantage supplied by increasing sampling duration. The costs of being selective are assumed to increase with time sampling. We suggest that females may benefit from assessing several signal components simultaneously in short samples instead of disproportionately increasing sampling duration.
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DOI : 10.1093/beheco/arw120
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Pharmacological, but not genetic, alteration of neural Epo modifies the CO2/H+ central chemosensitivity in postnatal mice
auteur
Sofien Laouafa, Anne-Sophie Perrin-Terrin, Florine Jeton, Elizabeth Elliot-Portal, Rose Tam, Laurence Bodineau, Nicolas Voituron, Jorge Soliz
article
Respiratory Physiology & Neurobiology, 2017, 242, pp.73-79. ⟨10.1016/j.resp.2017.04.003⟩
resume
Cerebral erythropoietin (Epo) plays a crucial role for respiratory control in newborn rodents. We showed previously that soluble Epo receptor (sEpoR: an Epo antagonist) reduces basal ventilation and hypoxic hyperventilation at postnatal day 10 (P10) and in adult mice. However, at these ages (P10 and adulthood), Epo had no effect on central chemosensitivity. Nevertheless, it is known that the sensitivity to CO2/H+ during the mammalian respiratory network maturation process is age-dependent. Accordingly, in this study we wanted to test the hypothesis that cerebral Epo is involved in the breathing stimulation induced by the activation of central CO2/H+ chemoreceptors at earlier postnatal ages. To this end, en bloc brainstem-spinal cord preparations were obtained from P4 mice and the fictive breathing response to CO2-induced acidosis or metabolic acidosis was analyzed. This age (P4) was chosen because previous research from our laboratory showed that Epo altered (in a dose- and time-dependent manner) the fictive ventilation elicited in brainstem-spinal cord preparations. Moreover, as it was observed that peripheral chemoreceptors determined the respiratory sensitivity of central chemoreceptors to CO2, the use of this technique restricts our observations to central modulation. Our results did not show differences between preparations from control and transgenic animals (Tg21: overexpressing cerebral Epo; Epo-TAgh: cerebral Epo deficient mice). However, when Tg21 brainstem preparations were incubated for 1 h with sEpoR, or with inhibitors of ERK/Akt (thus blocking the activation of the Epo molecular pathway), the fictive breathing response to CO2-induced acidosis was blunted. Our data suggest that variation of the Epo/sEpoR ratio is central to breathing modulation during CO2 challenges, and calls attention to clinical perspectives based on the use of Epo drugs at birth in hypoventilation cases.
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DOI : 10.1016/j.resp.2017.04.003
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Gammarus fossarum as a sensitive tool to reveal residual toxicity of treated wastewater effluents
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Adriana Wigh, Olivier Geffard, Khedidja Abbaci, Adeline François, Patrice Noury, Alexandre Bergé, Emmanuelle Vulliet, Bruno Domenjoud, Adriana Gonzalez-Ospina, Sylvie Bony, Alain Devaux
article
Science of the Total Environment, 2017, 584, pp.1012-1021. ⟨10.1016/j.scitotenv.2017.01.154⟩
resume
Wastewater treatment plants (WWTPs) are one of the main sources of freshwater pollution eventually resulting in adverse effects in aquatic organisms. Treated effluents can contain many micropollutants at concentrations often below the limit of chemical quantification. On a regulatory basis, WWTP effluents have to be non-toxic to the aquatic environment, wherefore not only chemical abatement but also ecotoxicological evaluation through relevant bioassays is required. Standardized bioassays currently used are often not sensitive enough to reveal a residual toxicity in treated effluents. Therefore, attention must be paid to the development of better-adapted approaches implementing more sensitive organisms and relevant endpoints. In this study, the toxicity of two differently treated effluents (activated sludge treated effluents with and without ozonation) towards the ecologically relevant species Gammarus fossarum was evaluated. Organism fitness traits such as reproduction and sperm DNA integrity were followed in exposed organisms. In complement, enzymatic biomarkers were measured indicating the presence of neurotoxic compounds (acetylcholinesterase activity), the presence of pathogens likely to increase the toxic effects of chemical compounds (phenol-oxidase activity), and the presence of toxic compounds inducing detoxification mechanisms (glutathione-S-transferase activity). Enzymatic activities were not modified, but significant sub-lethal effects were observed in exposed organisms. In both effluents, females showed a retarded molt cycle, a reduced fecundity and fertility, and > 90% of developed embryos exhibited developmental malformations. In addition, a slight but significant genotoxic effect was measured in gammarid sperm. In a whole, no difference in toxicity was found between both effluents. Coupling reproduction impairment and genotoxicity assessment in Gammarus fossarum seems to be a valuable and sensitive tool to reveal residual toxicity in effluents containing a mixture of micropollutants at very low concentrations. Finally, a direct relationship between the observed toxic responses and the quantified micropollutant concentrations could not be evidenced.
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DOI : 10.1016/j.scitotenv.2017.01.154
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Functional importance of freshwater amphipods in the leaf litter recycling process: the role of leaf litter characteristics
auteur
Christophe Piscart, Laura Pellan, Sara Puijalon, Mathieu Santonja
article
Biodiversity Journal, 2017, 8 (2), pp.429-430
resume
Impact of leaf characteristics on the keystone amphipod species for litter decomposition process.
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Manipulating waterbody hydroperiod affects movement behaviour and occupancy dynamics in an amphibian
auteur
Emilie Tournier, Aurélien Besnard, Virginia Tournier, Hugo Cayuela
article
Freshwater Biology, 2017, 62 (10), pp.1768-1782. ⟨10.1111/fwb.12988⟩
resume
Species that occur in ephemeral habitats such as temporary waterbodies have evolved specific strategies that allow them to respond to spatial and temporal variations in water availability and quality. Their life-history strategies, involving complex life cycles, have evolved to allow individuals to escape deteriorating environmental conditions when a waterbody dries up. These adaptations have led to the emergence of complex movement behaviour, which might then be expected to affect the spatiotemporal dynamics of reproduction. To date, few empirical studies have investigated how the risks of waterbody drying out affects movement behaviour at the individual level and how movement decisions then shape waterbody occupancy dynamics. In this study, we examined this issue in an endangered amphibian, the yellow-bellied toad (Bombina variegata). For this purpose, we experimentally manipulated waterbody hydroperiod and collected capture-recapture and presence-absence data in 334 waterbodies located in 15 B.variegata populations in the region of Geneva (Switzerland) during a 5-year period (2012-2016). The results of our analyses reveal that the waterbody hydroperiod affects this species' movement behaviour. Adults were less likely to leave waterbodies with a long hydroperiod both intra- and inter-annually. In addition, breeding occupancy strongly depended on a waterbody's hydroperiod. In particular, interannual changes in breeding occurrence were less frequent in waterbodies with a long hydroperiod. Our findings show that the hydroperiod strongly affects ecological processes at different levels, from individuals' movement decisions to waterbody occupancy dynamics. The results demonstrate that adults adjust their movement decisions according to the risk of breeding failure driven by the hydroperiod, which then affects the waterbody occupancy dynamics.
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DOI : 10.1111/fwb.12988
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Variability of surface and underwater nocturnal spectral irradiance with the presence of clouds in urban and peri-urban wetlands
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Jean Secondi, Valentin Dupont, Aurélie Davranche, Nathalie Mondy, Thierry Lengagne, Marc Thery
article
PLoS ONE, 2017, 12 (11), pp.e0186808. ⟨10.1371/journal.pone.0186808⟩
resume
Artificial light at night (ALAN) is an increasing phenomenon worldwide. It causes a wealth of biological and ecological effects that may eventually affect populations and ecosystems. Despite the growing concern about ALAN, little is known about the light levels species are exposed to at night, especially for wetlands and underwater habitats. We determined noctur- nal irradiance in urban and peri-urban wetlands above and under water, and assessed the effect of cloud cover on the variability of ALAN across the urban gradient. Even in aquatic habitats, cloud cover could increase irradiance beyond values observed during clear full moon nights. We report a negative relationship between baseline irradiance and the increase in irradiance during overcast nights. According to this result and previous studies, we propose that the change in the variation regime of ALAN between the urban center and rural land at its periphery is a usual feature. We discuss the ecological and evolutionary implications of this spatial variation in the urban and peri-urban environment.
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DOI : 10.1371/journal.pone.0186808
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Distribution spatiale et mobilité du phosphore sédimentaire dans une retenue hydroélectrique
auteur
Anne Rapin, Marion Rabiet, Malagorzata Grybos, Brice Mourier, Alexis Fay, Tim Kestens, Véronique Deluchat
article
Revue Francaise des Sciences de l'Eau, 2017
resume
Malgré la réduction des rejets de phosphore (P) dans l’environnement, les efflorescences phytoplanctoniques sont toujours observées dans un grand nombre de masses d’eau. C’est notamment le cas dans les retenues de barrage où la perturbation de la continuité sédimentaire peut conduire à une accumulation importante de phosphore au sein du compartiment sédimentaire. Ainsi, pour lutter contre l’eutrophisation, une meilleure connaissance de la distribution, de la réactivité et de la mobilité du P sédimentaire s’avère indispensable. Dans ce contexte, les sédiments de surface de la retenue de Champsanglard (Creuse, France) ont été prélevés en différents points selon un gradient amont/aval. Une caractérisation physico-chimique (granulométrie; teneurs en P, Fe, Al, matière organique; fractionnement chimique du P suivant le protocole de RYDIN et WELCH [1998]) a été effectuée afin d’évaluer le potentiel de relargage de P de ces sédiments. Les résultats montrent une évolution de la concentration et de la distribution du P dans les sédiments de surface dans la retenue de l’amont vers l’aval (de 1,5 à 2,3 mg P∙gsec -1), qui semble corrélée avec l’évolution de la granulométrie. L’analyse du fractionnement chimique a montré que le P était majoritairement lié aux oxyhydroxydes de Fe et Mn amorphes (66 %), ces concentrations augmentant également à l’approche du barrage. Ces résultats indiquent que les conditions d’oxydoréduction sont l’un des paramètres clés du contrôle de la remobilisation du P sédimentaire vers la colonne d’eau. À l’opposé, le P associé aux fractions de la matière organique et de l’aluminium ne semble quant à lui ne pas évoluer spatialement de façon significative.
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Chironomidae traits and life history strategies as indicators of anthropogenic disturbance
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Sonia R.Q. Serra, Manuel A. S. Graça, Sylvain Dolédec, João Feio Maria
article
Environmental Monitoring and Assessment, 2017, 189 (326), pp.1-16. ⟨10.1007/s10661-017-6027-y⟩
resume
In freshwater ecosystems, Chironomidae are currently considered indicators of poor water quality because the family is often abundant in degraded sites. However, it incorporates taxa with a large ecological and physiological diversity and different sensitivity to impairment. Yet, the usual identification of Chironomidae at coarse taxonomic levels (family or subfamily) masks genus and species sensitivities. In this study, we investigate the potential of taxonomic and functional (traits) composition of Chironomidae to de- tect anthropogenic disturbance. In this context, we test- ed some a priori hypotheses regarding the ability of Chironomidae taxonomic and trait compositions to dis- criminate Mediterranean streams affected by multiple stressors from least-disturbed streams. Both taxonomic and Eltonian trait composition discriminated sites ac- cording to their disturbance level. Disturbance resulted in the predicted increase of Chironomidae with higher number of stages with hibernation/diapause and of taxa with resistance forms and unpredicted increase of the proportion of taxa with longer life cycles and few gen- erations per year. Life history strategies (LHS), corre- sponding to multivoltine Chironomidae that do not in- vest in hemoglobin and lack strong spring synchroniza- tion, were well adapted to all our Mediterranean sites with highly changeable environmental conditions. Medium-size animals favored in disturbed sites where the Mediterranean hydrological regime is altered, but the reduced number of larger-size/carnivore Chironomids suggests a limitation to secondary produc- tion. Results indicate that Chironomidae genus and re- spective traits could be a useful tool in the structural and functional assessment of Mediterranean streams. The ubiquitous nature of Chironomidae should be also espe- cially relevant in the assessment of water bodies natu- rally poor in other groups such as the Ephemeroptera, Plecoptera, and Trichoptera, such as the lowland rivers with sandy substrates, lakes, or reservoirs.
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DOI : 10.1007/s10661-017-6027-y
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Long-term trends in trait structure of riverine communities facing predation risk increase and trophic resource decline
auteur
Adrien Latli, Jean-Pierre Descy, Cédric Mondy, Mathieu Floury, Laurent Viroux, William Otjacques, Jonathan Marescaux, Eric Depiereux, Michael Ovidio, Philippe Usseglio-Polatera, Patrick Kestemont
article
Ecological Applications, 2017, 27 (8), pp. 2458-2474. ⟨10.1002/eap.1621⟩
resume
Many large European rivers have undergone multiple pressures that have strongly impaired ecosystem functioning at different spatial and temporal scales. Global warming and other environmental changes have favored the success of invasive species, deeply modifying the structure of aquatic communities in large rivers. Some exogenous species could alter trophic interactions within assemblages by increasing the predation risk for potential prey species (top-down effect) and limiting the dynamics of others via resource availability limitation (bottom-up effect). Furthermore, large transboundary rivers are complex aquatic ecosystems that have often been poorly investigated so that data for assessing long-term ecological trends are missing. In this study, we propose an original approach for investigating long-term combined effects of global warming, trophic resource decrease, predation risk, and water quality variations on the trait-based structure of macroinvertebrate and fish assemblages over 26 yr (1985-2011) and 427-km stretch of the river Meuse (France and Belgium). The study of temporal variations in biological, physiological, and ecological traits of macroinvertebrate and fish allowed identifying community trends and distinguishing impacts of environmental perturbations from those induced by biological alterations. We provide evidence, for this large European river, of an increase in water temperature (close to 1 degrees C) and a decrease in phytoplankton biomass (-85%), as well as independent effects of these changes on both invertebrate and fish communities. The reduction of trophic resources in the water column by invasive molluscs has dramatically affected the density of omnivorous fish in favor of invertebrate feeders, while scrapers became the major feeding guild among invertebrates. Macroinvertebrate and fish communities have shifted from large-sized organisms with low fecundity to prolific, small-sized organisms, with early maturity, as a response to increased predation pressure.
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DOI
DOI : 10.1002/eap.1621
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Clinical relevance of FASII bypass in Staphylococcus aureus
auteur
Karine Gloux, Mélanie Guillemet, Charles Soler, Claire Morvan, David Halpern, Christine Pourcel, Hoang Vu Thien, Gilles Lamberet, Alexandra Gruss
article
Antimicrobial Agents and Chemotherapy, 2017, 61 (5), ⟨10.1128/AAC.02515-16⟩
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The need for new antimicrobials to treat bacterial infections has led to the use of fatty acid synthesis (FASII) enzymes as front-line targets. However, recent studies suggest that FASII inhibitors may not work against the opportunist pathogen Staphylococcus aureus, as environmental fatty acids favor emergence of multi-anti-FASII resistance. As fatty acids are abundant in the host, and one FASII inhibitor, triclosan, is widespread, we investigated whether fatty acid pools impact resistance in clinical and veterinary S. aureus isolates. Simple addition of fatty acids to screening medium led to a 50% increase in triclosan resistance, as tested in 700 isolates. Moreover, non-culturable triclosan-resistant fatty acid auxotrophs, which escape detection under routine conditions, were uncovered in primary patient samples. FASII bypass in selected isolates correlated with polymorphisms in acc and fabD loci. We conclude that fatty-acid-dependent strategies to escape FASII inhibition are common among S. aureus isolates and correlate with anti-FASII resistance and emergence of non-culturable variants.
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DOI
DOI : 10.1128/AAC.02515-16
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I’m not like everybody else: urbanization factors shaping spatial distribution of native and invasive ants are species-specific
auteur
Jérôme M.W. Gippet, Nathalie Mondy, Julita Diallo-Dudek, Arnaud Bellec, Adeline Dumet, Lubiana Mistler, Bernard Kaufmann
article
Urban Ecosystems, 2017, 20, pp.157-169. ⟨10.1007/s11252-016-0576-7⟩
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Urbanization is a major global change inducing complex and multiple modifications of landscapes and eco- systems. The spatial distributions of organisms experiencing these modifications will likely shift specifically, depending on each species’ response to each environmental modification induced by urbanization. We sampled two ant genera (Lasius and Tetramorium) at 1248 locations along an urbani- zation gradient in Lyon, France and used high resolution spa- tial layers for 18 spatial (e.g., open habitat fragmentation, bio- climatic data and surface temperatures) and temporal (e.g., comparison of Normalized Difference Vegetation Index be- tween 1986 and 2015) environmental variables associated with urbanization. Coupling two different analytical methods (Outlying Mean Index and Boosted Regression Trees), we showed that each species’ distribution was influenced by its own combination of environmental factors. Two morphologically cryptic Tetramorium species (T. sp.E and T. sp.U2) were both highly abundant but with opposite responses to urbanization: while T. sp.E was favored by urbanized habitat, T. sp.U2 avoided urbanized areas. Among Lasius species, we detected 63 occurrences of the invasive ant Lasius neglectus, the distribution of which was favored only by embankments along roads. We found that, even at this reduced spatial scale, climatic effects influenced most species and interacted with urbanization factors.
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DOI
DOI : 10.1007/s11252-016-0576-7
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titre
Temporal variability in taxonomic and trait compositions of invertebrate assemblages in two climatic regions with contrasting flow regimes
auteur
Sylvain Dolédec, Jessica Tilbian, Nuria Bonada
article
Science of the Total Environment, 2017, 599-600, pp.1912-1921. ⟨10.1016/j.scitotenv.2017.05.057⟩
resume
Context Understanding natural temporal changes in Mediterranean rivers with contrasting flow regimes in relation to those of temperate rivers may prove helpful in predicting effects of climate change on aquatic biodiversity. Goal We aimed to compare temporal variability in taxonomic and trait compositions of nearly natural rivers in two climatic regions with varying flow regimes to address the effects of future climate changes on aquatic biodiversity in reference conditions. Methods We analysed taxonomic and biological trait compositions using the Foucard multivariate method to compare within-site temporal variability levels and the evolution of within-date spatial variability patterns. In addition, we assessed the effects of temporal variability levels on taxonomic and functional diversity and on community specialization. Results Our results reveal (i) highly fluctuating environments of the Mediterranean region, particularly in intermittent rivers, which lead to higher levels of temporal variability in both taxonomic and trait compositions of benthic invertebrate assemblages, with marked synchrony in Mediterranean streams linked to contrasting flow characteristics; (ii) higher degrees of taxonomic richness associated with higher levels of functional diversity in Mediterranean rivers relative to temperate rivers, (iii) higher temporal stability for functional diversity and trait compositions of benthic invertebrate assemblages than for taxonomic richness and compositions; and (iv) a recovery of all diversity metrics following drying events in intermittent sites. Conclusion This study offers insight into a rarely addressed question concerning the temporal variability of trait compositions in benthic invertebrate assemblages among rivers differing in terms of flow regimes. It suggests that temperate rivers will experience higher levels of temporal variability in terms of taxonomic and trait compositions under future climatic change scenarios, even in sites that will remain perennial, resulting in higher levels of taxonomic and functional diversity. This lack of temporal stability in least-disturbed situations should be taken into account when developing bioassessment tools based on reference conditions.
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DOI
DOI : 10.1016/j.scitotenv.2017.05.057
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Does testosterone affect foraging behavior in male frogs?
auteur
Julia L. Desprat, Nathalie Mondy, Thierry Lengagne
article
Hormones and Behavior, 2017, 90, pp.25-30. ⟨10.1016/j.yhbeh.2017.02.003⟩
resume
During the breeding season, males often produce costly and extravagant displays or physical ornaments to attract females. Numerous studies have established that testosterone could directly influence the expression of certain sexual signals. However, few of these studies have focused on the indirect role that testosterone could play in modulating prey detection and visual performance to improve the foraging ability of males and hence their acquisition of nutritional resource. In the present study, we experimentally modified the testosterone levels of European tree frog males (Hyla arborea), staying in the natural range previously measured in the field, and we investigated the effect of testosterone on the foraging ability of individuals. Foraging capacities were measured on males placed in an arena with a virtual cricket moving on a computer screen. Our results demonstrated a significant effect of testosterone on the hunting behavior of H. arborea. We observed that testosterone reduced the orientation latency to virtual prey for supplemented males compared to controls. In addition, testosterone significantly increased the attack promptness of male frogs. Finally, our experiment did not demonstrate any impact of testosterone on male attack success.
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DOI
DOI : 10.1016/j.yhbeh.2017.02.003
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Early Triassic fluctuations of the global carbon cycle: New evidence from paired carbon isotopes in the western USA basin
auteur
Gwénaël Caravaca, Christophe Thomazo, Emmanuelle Vennin, Nicolas Olivier, Théophile Cocquerez, Gilles Escarguel, Emmanuel Fara, James F. Jenks, Kevin G. Bylund, Daniel A. Stephen, Arnaud Brayard
article
Global and Planetary Change, 2017, 154, pp.10-22. ⟨10.1016/j.gloplacha.2017.05.005⟩
resume
In the aftermath of the catastrophic end-Permian mass extinction, the Early Triassic records recurrent perturbations in the carbon isotope signal, most notably during the Smithian and through the Smithian/Spathian Boundary (SSB; ~ 1.5 myr after the Permian/Triassic boundary), which show some of the largest excursions of the Phanerozoic. The late Smithian also corresponds to major biotic turnovers and environmental changes, such as temperature fluctuations, that deeply impacted the recovery after the end-Permian mass extinction. Here we document the paired carbon isotope signal along with an analysis of the trace and major elements at the long-known Hot Springs section (southeastern Idaho, USA). This section records Early Triassic sediments from the Griesbachian-Dienerian up to the lower Spathian. We show that the organic and carbonate δ13C variations mirror the signals identified at a global scale. Particularly, the middle Smithian-SSB event represented by a negative-positive isotopic couplet is well identified and is not of diagenetic origin. We also document a positive excursion potentially corresponding to the Dienerian/Smithian Boundary. Observed Smithian-Spathian excursions are recorded similarly in both the organic and carbonate reservoirs, but the organic matter signal systematically shows unexpectedly dampened variations compared to its carbonate counterpart. Additionally, we show that variations in the net isotopic effect (i.e., Δ13C) probably resulted from a complex set of forcing parameters including either a mixing between terrestrial and marine organic matter depending on the evolution of the depositional setting, or variations in the biological fractionation. We establish that the Δ13C signal cannot be directly related to CO2-driven temperature variations at Hot Springs. Even though the carbon isotope signal mirrors the Early Triassic variations known at the global scale, the Hot Springs signal probably also reflects local influences on the carbon isotopes that are neither diagenetic nor representative of the global exogenic carbon cycle
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DOI
DOI : 10.1016/j.gloplacha.2017.05.005
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https://sde.hal.science/hal-01547080/file/Caravaca%20et%20al%2C%20ET%20fluctuations%20of%20the%20carbon%20cycle%2C%20hot%20springs.pdf BibTex