Drawing lessons from a pluridisciplinary approach associating stakeholders for a better management of a bivalve population (French Atlantic coast)?
(Estuarine, Coastal and Shelf Science. vol. 251, n° 0272-7714, pp. 107194, 01/04/2021)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LMAP, UPPA, CNRS
Reconstruction of fire regime changes in the French Mediterranean region during the last 8,500 years using microcharcoal
Nowadays, the Mediterranean region is strongly impacted by fires. Projected warming scenarios suggest increasing fire risk in this region considered as hot-spot of the climate change (Liu et al., 2010; Pechony and Shindell, 2010). However, models based on modern-day statistical relationships do not properly account for interactions between climate, vegetation, and fire. In addition, process-based models must be tested not only against modern observations but also under different past climate conditions reflecting the range of climate variability projected for the next centuries (Hantson et al. 2016). Marine sediments are a major source of fire history of nearby land masses. Here, we present a unique 8,500 yr long record of biomass burning changes from southeastern France based on a marine microcharcoal sedimentary record from the Gulf of Lion, located in the subaqueous Rhone river delta. Sediment delivery to the Gulf of Lion comes mainly from the Rhône River draining a large watershed in southeast France (ca.100,000 km2). Due to the direction of dominant winds blowing from the North-North-West (Mistral and Tramontane) and carrying fine particles from the land to the sea, the microcharcoal record likely reflects the biomass burning in the Rhone watershed and South-East of France. Our results show multi-centennial to millennial changes in biomass burning with a periodicity of 1000 years for the full record and between 500 and 700 years before 5,000 cal BP and after 3,000 cal BP. Large peaks of biomass burning are associated with marked dry periods observed in the region. Burning of biomass is higher when the region is dominated by xerophytic vegetation than when mesophyte vegetation dominates. The trend and periodicity of the biomass burning record suggest a predominant climatic control of fire occurrences since 8,500 cal BP in this region
(01/04/2021)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CEFREM, UPVD, INSU - CNRS, CNRS, LOCEAN, MNHN, IRD, INSU - CNRS, SU, CNRS, IPSL (FR_636), ENS-PSL, PSL, UVSQ, CEA, INSU - CNRS, X, IP Paris, CNES, SU, CNRS, UPCité, LOCEAN-VOG, LOCEAN, MNHN, IRD, INSU - CNRS, SU, CNRS, IPSL (FR_636), ENS-PSL, UVSQ, CEA, INSU - CNRS, X, CNES, SU, CNRS, UPCité, HNHP, MNHN, UPVD, CNRS
Dissolved organic matter modulates the impact of herbicides on a freshwater alga: A laboratory study of a three-way interaction
In freshwater environments, microorganisms such as microalgae are influenced by the concentrations of dissolved chemicals but can modify the fate of these substances by biosorption, accumulation and even metabolization. In this laboratory study, we assessed the growth and physiology of non-axenic cultures of the chlorophyte Sphaerellopsis sp. exposed to environmental concentrations of diuron, irgarol and S-metolachlor (0.5, 0.5 and 5 μg·L−1, respectively) singly and in mixture, in the presence or absence of natural dissolved organic matter (DOM). The growth, photosynthetic efficiency and relative intracellular lipid content of Sphaerellopsis sp., as were measured after 14 days of exposure, as were the concentrations of bacteria in the cultures. DOM absorbance and fluorescence, and concentrations of the herbicides and their metabolites in the culture medium were also recorded. The growth of Sphaerellopsis sp. was very low in the absence of DOM but dramatically enhanced in treatments where DOM was added. As a result, the toxicity of the herbicides observed in treatments without DOM was overcome in those where DOM was added. The chemical characteristics of DOM were modified by the microalgae, and the fate of the herbicides was affected by the interaction between microorganisms (both bacteria and algae) and the DOM. Herbicide concentrations decreased over time, with a simultaneous increase in some of their metabolites, suggesting a biological degradation in the presence of DOM.
(Science of the Total Environment. vol. 782, n° 0048-9697, pp. 146881, 01/04/2021)
UR EABX, INRAE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, BE, IFREMER
Sediment archives reveal irreversible shifts in plankton communities after World War II and agricultural pollution
(Current Biology, n° 0960-9822, 01/04/2021)
DYNECO, IFREMER, LERBO, COAST, IFREMER, BE, IFREMER, LEMAR, IRD, IFREMER, UBO EPE, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, GM, IFREMER, LERBN, COAST, IFREMER, LGO, UBS, IFREMER, UBO EPE, CNRS, IFREMER
The sediments of Lake Singkarak and Lake Maninjau in West Sumatra reveal their earthquake, volcanic and rainfall history
Natural hazards such as earthquakes, volcanic activity, and heavy rainfall causing floods and debris avalanches are common phenomena in many tropical settings, including the island of Sumatra, located in the Indonesian archipelago. To enhance our understanding of the recurrence of these often destructive events, we studied the sedimentary infill of two lakes in the Padang highlands, West Sumatra. This includes Lake Singkarak, a tectonically-formed lake located on a step-over of a major strike-slip fault system (the Sumatran Fault), and Lake Maninjau, a caldera lake. Both lakes are located -300 km from the Sunda subduction trench and surrounded by steep slopes and a chain of active volcanoes. Hence, considering their unique tectonic setting, these lakes may potentially record a wide range of natural hazards that affect the region. A combination of seismic-reflection pro¬files and short sediment cores revealed that both lakes indeed record various types of natural hazards, each with their own sedimentary response to a specific type of event. Lake Singkarak can be used to study past floods and major debris avalanches in addition to high-magnitude megathrust earthquakes, while traces of past intraplate earthquakes have been identified in both lakes. Furthermore, we argue that Lake Singkarak is an ideal recorder of volcanic activity in the region, while Lake Maninjau itself can pose a volcanic hazard toits surroundings as demonstrated by potential activity of the volcano below the lake
(Sedimentary Geology. vol. 416, n° 0037-0738, pp. 105863, 01/04/2021)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Etude comparative de l’écodynamique de micropolluants organohalogénés historiques et d’intérêt émergent dans l’estuaire de Seine
Dans un contexte de changement global, les effets de la pollution d'origine anthropique sont importants. Cette pollution est liée à l'urbanisation, l'activité industrielle ou encore l'agriculture intensive. Ces multiples sources génèrent de nombreuses catégories de pollution, dont la pollution chimique. Afin de mieux comprendre l'écodynamique de certains polluants ubiquistes, toxiques et bioaccumulables, l'estuaire de Seine a été choisi car il constitue le réceptacle final d'un bassin versant soumis à une forte pression anthropique. Plusieurs compartiments y ont été étudiés. Quatre espèces d'oiseaux marins (goéland argenté : Larus argentatus ; goéland brun : Larus fuscus ; goéland marin : Larus marinus ; cormoran huppé : Phalacrocorax aristotelis) sentinelles, bioindicatrices, représentatives d’un niveau trophique élevé et ayant des habitats et des habitudes d'alimentation variés et caractéristiques des milieux estuariens ont été choisies afin de suivre leur imprégnation en différentes classes de contaminants historiques tels que les polychlorobiphényles (PCB), les pesticides organochlorés (OCP) et les polybromodiphényléthers (PBDE) et de contaminants d’intérêt plus émergents comme les composés per- et poly-fluoroalkylés (PFAS). Les PCB, l'hexabromocyclododécane (HBCDD) et les PFAS ont été également suivis dans le milieu de vie et le réseau trophique de la sole commune (Solea solea) afin d’appréhender les transferts du sédiment vers le biote, au sein du réseau trophique benthique, mais aussi entre les stades juvéniles d'un organisme d’intérêt halieutique et écologique majeur.
(30/03/2021)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Benefit versus cost trade-offs of masting across seed-to-seedling transition for a dominant subtropical forest species
Masting is a common reproductive strategy regulating seedling regeneration in many perennial plant species. The evolutionary origins and functional benefits of masting have been explained by well-supported hypotheses relating to economies of scale of seed production. Nevertheless, our understanding of the potential costs of masting for the plant seed-to-seedling transitions remains limited. We tracked the seed fate and documented changes in the seed spatial distribution patterns during the seed-to-seedling transition process of Castanopsis fargesii, a dominant species of subtropical evergreen broad-leaved forests in China under natural conditions for more than 6 years. Masting resulted in a high proportion of seeds escaping predation by vertebrates and rodents, supporting the predator satiation hypothesis. However, it increased the pre-dispersal seed predation by insects, and decreased the seed germination rate due to a negative effect on seed mass. This resulted in seed-to-seedling transition rates during mast years to be roughly half as much as during non-mast years. In addition, masting negatively affected the spatial rearrangement of seeds, resulting in a spatial aggregative distribution pattern of newly germinated seedlings. The combined negative effects of smaller seeds and spatially aggregated seedlings reduced the survival rate of newly germinated seedlings at seedling establishment stage. Synthesis. Considering the whole seed-to-established seedling transition process, the benefits of masting on seedling recruitment due to the effective seed predator situation by vertebrates and rodents were decreased by the additional costs on seed mass, seed germination, seed spatial arrangement and seedling establishment. Our results highlight the importance of considering both the positive and negative effects of masting at each stage of the seed-to-seedling transition. Inferences based on seed predation and recruitment of newly germinated seedlings alone would lead to an overly optimistic conclusion about the benefits of masting. © 2021 British Ecological Society
(Journal of Ecology. vol. 109, n° 0022-0477, pp. 3087-3098, 26/03/2021)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Monitoring of 53 contaminants of emergent concern: occurrence in effluents, sludges, and surface waters upstream and downstream of 7 wastewater treatment plants
(25/03/2021)
INERIS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ISA, UCBL, INC-CNRS, CNRS
Chronic feeding exposure to virgin and spiked microplastics disrupts essential biological functions in teleost fish
Toxicity of polyethylene (PE) and polyvinyl chloride (PVC) microplastics (MPs), either virgin or spiked with chemicals, was evaluated in two short-lived fish using a freshwater species, zebrafish, and a marine species, marine medaka. Exposures were performed through diet using environmentally relevant concentrations of MPs over 4 months. No modification of classical biomarkers, lipid peroxidation, genotoxicity or F0 behaviour was observed. A significant decrease in growth was reported after at least two months of exposure. This decrease was similar between species, independent from the type of MPs polymer and the presence or not of spiked chemicals, but was much stronger in females. The reproduction was evaluated and it revealed a significant decrease in the reproductive output for both species and in far more serious numbers in medaka. PVC appeared more reprotoxic than PE as were MPs spiked with PFOS and benzophenone-3 compared to MPs spiked with benzo[a]pyrene. Further, PVC-benzophenone-3 produced behavioural disruption in offspring larvae. These results obtained with two species representing different aquatic environments suggest that microplastics exert toxic effects, slightly different according to polymers and the presence or not of sorbed chemicals, which may lead in all cases to serious ecological disruptions.
(Journal of Hazardous Materials. vol. 415, n° 0304-3894, pp. 125626, 11/03/2021)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LSEA MARBEC, UMR MARBEC, IRD, IFREMER, UM, CNRS, MDH, UB, UMR MARBEC, IRD, IFREMER, UM, CNRS, GABI, INRAE
High-Sensitivity Permeation Analysis of Ultrasmall Nanoparticles Across the Skin by Positron Emission Tomography
Ultrasmall nanoparticles (US-NPs; <20 nm in hydrodynamic size) are now included in a variety of pharmacological and cosmetic products, and new technologies are needed to detect at high sensitivity the passage of small doses of these products across biological barriers such as the skin. In this work, a diffusion cell adapted to positron emission tomography (PET), a highly sensitive imaging technology, was developed to measure the passage of gold NPs (AuNPs) in skin samples in continuous mode. US-AuNPs (3.2 nm diam.; TEM) were functionalized with deferoxamine (DFO) and radiolabeled with 89Zr(IV) (half-life: 3.3 days, matching the timeline of diffusion tests). The physicochemical properties of the functionalized US-AuNPs (US-AuNPs-PEG-DFO) were characterized by FTIR (DFO grafting; hydroxamate peaks: 1629.0 cm–1, 1569.0 cm–1), XPS (presence of the O═C–N C 1s peak of DFO at 287.49 eV), and TGA (organic mass fraction). The passage of US-AuNPs-PEG-DFO-89Zr(IV) in skin samples was measured by PET, and the diffusion parameters were extracted thereby. The signals of radioactive US-AuNPs-PEG-DFO-89Zr(IV) leaving the donor compartment, passing through the skin, and entering the acceptor compartment were detected in continuous at concentrations as low as 2.2 nM of Au. The high-sensitivity acquisitions performed in continuous allowed for the first time to extract the lag time to the start of permeation, the lag time to start of the steady state, the diffusion coefficients, and the influx data for AuNPs permeating into the skin. PET could represent a highly valuable tool for the development of nanoparticle-containing topical formulations of drugs and cosmetics.
(Bioconjugate Chemistry. vol. 32, n° 1043-1802, pp. 729-745, 10/03/2021)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS