Contrasting soil‐ and canopy‐nurse effects in metalliferous systems may be explained by dominant plant functional strategies
Plant-plant interaction studies in metalliferous systems have focused either on the role of facilitation or on negative effects of elemental allelopathy. However, no studies have investigated both of these effects in the same system, and their relationships with the functional strategy of the nurse species, although this is crucial for the ecological restoration of polluted sites. We assessed the effects of two dominant nurse species, with apparent contrasting strategies, on two target species on a slag heap in the Pyrenees (France). We quantified both long-term soil-engineering and short-term canopy effects on the growth of two target species. We also measured morphological traits and leaf metal concentration of the two nurse species and their effects on air moisture, temperature and vapour pressure deficit. Nurse functional strategies, as inferred from morphological traits and leaf metal concentration seem to drive their long-term soil engineering effects on target species: Gypsophila repens, the relative larger and more exploitative species with high leaf metal concentration, had negative long-term effects likely due to elemental allelopathy, whereas Minuartia verna, the relative smaller and more conservative species with lower amount of metals in leaves, had neutral long-term effects. Although Gypsophila repens had a slightly stronger positive effect on microclimate than Minuartia verna, this did not turn into higher short-term effects for the target species. Synthesis and applications: Our study highlights the diverse long and short-term nurse effects on companion species in metalliferous systems. Different nurse species can improve the performance of companion species by mitigation of climatic stress, and ultimately help speed-up the restoration of polluted environments. However, species status regarding leaf metal accumulation has to be verified. For species having a higher metal concentration in their leaves, positive microclimatic effects may be offset by local increase of soil contamination on the long-term.
(Journal of Applied Ecology. vol. 60, n° 0021-8901, pp. 278 - 290, 25/11/2022)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UMR ISPA, Bordeaux Sciences Agro, INRAE
Forest canopy and mistletoe infestation alter the facilitative effects of Juniperus oxycedrus s.l. on woody seedlings on Mount Lebanon (Lebanon)
Questions In this study we investigated the direct effect of the shrub Juniperus oxycedrus s.l. on Mediterranean woody species regeneration, and how this interaction can be modified by the juniper habit, the forest canopy and/or infestation of the juniper by the plant parasite Arceuthobium oxycedri. We also aimed at identifying species response groups in relation to their ecological requirements and successional strategies. Location North of Mount Lebanon, in Horsch Ehden natural reserve, a humid montane Mediterranean forest. Methods We compared the regeneration of all occurring woody species below and outside 111 Juniperus oxycedrus canopies using the random pair sampling method. We calculated eight relative interaction intensity indexes (RIIJuniper) corresponding to the eight treatment combinations of the three factors: forest canopy (forest/gap), mistletoe infestation (with/without) and juniper habit (spreading/erect). We analyzed the RII values at three different levels: community (all species grouped), species group and species. Results Overall, the regeneration of the woody community was facilitated by Juniperus oxycedrus. However, the forest cover significantly reduced the facilitative effect of Juniperus oxycedrus when the latter was not infested by Arceuthobium oxycedri. We identified three species response groups (A: highly facilitated; B: slightly facilitated to neutral; and C: neutral) determined by their response to both Juniperus oxycedrus canopy and forest cover. The most facilitated species were shade-tolerant/drought-intolerant late-successional species. Conclusions The results suggest the importance of shade tolerance in the complex mechanism of forest regeneration that is also affected by a parasite plant (Arceuthobium oxycedri), which boosts regeneration dynamics under forest cover by reducing shrub canopy cover.
(Journal of Vegetation Science. vol. 33, n° 1100-9233, 24/11/2022)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Multi-analytical approach to investigate sources of dissolved organic matter in a peri-urban watershed
Dissolved organic matter DOM corresponds to a complex mixture of molecules and macromolecules playing a major role in terrestrial and aquatic biogeochemical process. DOM heterogeneous composition allows it to have innumerable interactions with organic and inorganic compounds, affecting both their bioavailability and mobility in the environment. At the watershed scale, there are many sources of DOM towards the river such as diffuse inputs by leaching of different types of soils (e.g. forest, meadows, crops, urban impermeable areas...) or urban point inputs (storm overflows, WWTP discharges, stormwater discharges....). However, the influence of of all these sources on the composition of the aquatic DOM remains poorly understood to this day. In this context, the main objective of this study was to build a methodology to detect the different sources of DOM in the rivers. Using a detailed characterization of DOM, the aim was to identify physicochemical markers and construct source-specific fingerprints. For this purpose, approximately 150 samples were collected from natural and anthropogenic sources of DOM (forest, agricultural, wastewater and urban runoff). All samples were analyzed using an innovative approach based on the use of a wide range of analytical techniques: dissolved organic carbon measurement, optical properties (UV-Visible, 3D fluorescence, size exclusion chromatography coupled with UV-fluorescence detection) and molecular composition (high-resolution mass spectrometry coupled with liquid chromatography). A large amount of data has been generated, and processed by classical (Anova, TukeyHSD) and multivariate (PCA, MFA, DFA) statistical approaches. The results obtained allowed highlighting optical and molecular markers relevant for the identification of the selected sources. These markers inform on specific characteristics of DOM, such as the size of the molecules, the aromaticity content, the degree of humification, polarity and reactivity. In addition, complementarities and redundancies between optical and molecular characterization techniques is investigated. This research also contributes to select relevant markers for geochemical tracing models.
(23/11/2022)
RiverLy, INRAE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Leaf Metal Exclusion or Accumulation is Related to Soil Resource Exploitation Strategy in European Calamine Species: Evidence for a Leaf Elemental and Economic Spectrum?
(21/11/2022)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LASIRE, INC-CNRS, CNRS, UMR ISPA, Bordeaux Sciences Agro, INRAE, LPTC, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
CAGE-ARCLIM cruise: Culturing (sub)Arctic planktic foraminifera Neogloboquadrina pachyderma and Globigerina bulloides: Implications for ocean acidification and paleoceanography reconstructions
From the morning of June 23rd to the morning of June 30th 2022, the Department of Geosciences at UiT the Arctic University of Norway, arranged a scientific cruise on R/V “Helmer Hanssen aimed at sampling living planktic foraminifera (Neogloboquadrina pachyderma and Globigerina bulloides) for culturing experiments both onboard and continued at the culturing laboratory at the Department. The purpose is to investigate the physiological and calcification responses of this species to a wide range of temperature, salinity and carbonate chemistry as well as to establish Arctic-tailored proxy calibrations for paleoceanography reconstructions The cruise may be known as: CAGE22_4
(CAGE – Centre for Arctic Gas Hydrate, Environment and Climate Report Series. vol. 10, n° 2703-9625, 18/11/2022)
UiT, CEREGE, IRD, AMU, CdF (institution), INSU - CNRS, CNRS, INRAE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Direct and trophic exposure of polystyrene and environmental nanoplastics on Corbicula fluminea
(15/11/2022)
BIOSSE, UCO, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ULaval, INSU - CNRS, CNRS, GR, UR, INSU - CNRS, CNRS
Impact of spawning grounds water quality on early life stages of allis shad using an ex-situ experiment.
(15/11/2022)
UR EABX, INRAE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, RiverLy, INRAE
Sand-mud transition dynamics at embayed beaches during a typhoon season in eastern China
(Marine Geology. vol. 441, n° 0025-3227, pp. 106633, 01/11/2022)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Les « forêts » de pins maritimes d’Aquitaine, des nids à incendie ?
(30/10/2022)
LEHNA, UCBL, ENTPE, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UMR SAVE, UB, Bordeaux Sciences Agro, INRAE
Impact environnemental et sanitaire des particules de nickel émises par les activités minières en Nouvelle Calédonie
En produisant un peu plus de 158 000 tonnes de nickel (Ni) par an la Nouvelle-Calédonie fait partie des producteurs de Ni les plus importants au monde avec des sols riches en éléments traces métalliques. Cette exploitation massive de Ni est un enjeu économique majeur pour le pays (8 à 17 % du PIB annuel) au détriment de potentiels impacts environnementaux et sanitaires. En effet, l’exploitation de ces mines à ciel ouvert de latérites nickélifères entraine l’émission de particules ultrafines Ni et d’oxyde de nickel (NiO) disséminées dans l’environnement, par le vent, ou via le ruissellement des cours d’eau, mais également d’autres métaux présents dans ces sols. Ces particules peuvent, d’une part, être inhalées par les travailleurs des mines ainsi que par les populations environnantes, posant des questions relevant de la toxicologie humaine et, d’autre part, être transportées le long des cours d’eau douce proches des mines, pour se retrouver par dépôts ou lessivages vers l’aval jusqu’au lagon, impactant ainsi les organismes aquatiques, dont l’étude relève de l’écotoxicologie.D’un point de vue environnemental, peu d’études ont été menées en Nouvelle-Calédonie. Cependant, des premiers travaux sur les cours d’eau douce à proximité des mines ont permis de montrer des taux de Ni très importants accumulés dans les organismes sous influence minière, notamment, dans les anguilles du Pacifique. De façon à pouvoir documenter l’importance des impacts toxiques potentiellement infligés aux anguilles présentes sur ces sites, différents types d’approches ont été menées : (i) L’analyse des impacts toxiques des métaux sur Anguilla marmorata prélevée in situ lors d’une mission (mesures morphométriques, taux de métaux dans les organes, transcriptomiques) ; (ii) L’impact d’une exposition aux nanoparticules (NPs) de NiO, NiONPs, sur des hépatocytes d’anguilles in vitro, le foie étant une cible privilégie de la toxicité des métaux et un organe essentiel pour les anguilles. Ces approches ont permis de décrypter de façon précoce les mécanismes cellulaires et moléculaires d’impact cytotoxique, de stress oxydant, d’inflammation et de dysfonction mitochondriale suite à cette exposition.Parallèlement, l’exposition humaine aux NPs est une préoccupation de santé publique. Les NPs peuvent ainsi franchir la barrière alvéolo-capillaire, se retrouver dans la circulation générale et y exercer des effets délétères par des interactions directes avec le système cardiovasculaire et, notamment, les cellules endothéliales (HPAEC) tapissant la lumière des vaisseaux et contrôlant la réactivité vasculaire qui est modifiée après exposition aux NPs de Ni. Ces effets pourraient ainsi être potentialisés dans les pathologies cardiovasculaires. Les personnes souffrant de pathologies de la circulation pulmonaire (hypertension pulmonaire, HTP) pourraient donc constituer des populations à risque. Ainsi, il s’avère nécessaire de mieux caractériser, les mécanismes d’action toxiques induits par des poussières riches en Ni et par les NiONPs sur le système cardiovasculaire. Pour cela nous avons étudié, sur des HPAEC, les effets induits par les NiONPs sur la signalisation calcique, la réponse pro-inflammatoire et le rôle de stress oxydant dans les modifications observées, ainsi que les impacts de ces NPs en condition pathologique en utilisant un modèle in vitro mimant la dynamique vasculaire observée lors de l’HTP avec le système d’étirement STREX®. Nos résultats montrent que l'exposition aux NiONPs induit un stress oxydant, une réponse pro-inflammatoire ainsi que des altérations de l’homéostasie calcique et que ces effets sont potentialisés lorsque les cellules sont en conditions pathologiques. Ces travaux suggèrent donc que l'exposition aux NiONPs pourrait aggraver certains événements physiopathologiques chez les patients souffrant de maladies cardiovasculaires préexistantes telles que l’HTP, et que ces patients seraient plus sensibles à ces polluants particulaires.
(27/10/2022)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS