Use of scuba-diving for monitoring water oxygen and charophyte distribution in shallow-lakes of the Atlantic coast
The littoral lakes of the Atlantic coast constitute the largest freshwater shallow-lakes system in France. They are unique natural habitats in Europe, harboring a specific biodiversity, but they are strongly threatened by global changes, notably climate change and alien species invasion. We propose to use scientific scuba-diving as a tool for monitoring 4 of these lakes and better understanding their biogeochemical functioning and biodiversity. More specifically, we foresee to position underwater automatic probes in order to monitor temperature and oxygen variations on the long term, within densely-vegetated and vegetation-free areas. The use of scientific scuba-diving will help to accurately place the probes (particularly within invasive plant beds) and to perform the maintenance. We also want to use scuba-diving to gain knowledge about the distribution of charophytes living in these lakes. This aquatic vegetation is represented by scattered individuals that are difficult to observe beyond 1m depth and to sample through common methods (typically by grab or rake). Thus, scuba-diving may be of great help in checking for the presence of these species, determining their maximum growing depth, and collecting individuals for chemical-content analyses. To this end, we propose to use regular-spaced transects perpendicular to the shoreline. We believe that scuba-diving will be a fantastic resource for better understanding the functioning and biodiversity of these lakes and thus providing valuable information for their management and conservation.
(14/05/2023)
UR EABX, INRAE, ECLA, USMB [Université de Savoie] [Université de Chambéry], INRAE, OFB, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Moist and warm conditions in Eurasia during the last glacial of the Middle Pleistocene Transition
Abstract The end of the Middle Pleistocene Transition (MPT, ~ 800-670 thousand years before present, ka) was characterised by the emergence of large glacial ice-sheets associated with anomalously warm North Atlantic sea surface temperatures enhancing moisture production. Still, the direction and intensity of moisture transport across Eurasia towards potential ice-sheets is poorly constrained. To reconstruct late MPT moisture production and dispersal, we combine records of upper ocean temperature and pollen-based Mediterranean forest cover, a tracer of westerlies and precipitation, from a subtropical drill-core collected off South-West Iberia, with records of East Asia summer monsoon (EASM) strength and West Pacific surface temperatures, and model simulations. Here we show that south-western European winter precipitation and EASM strength reached high levels during the Marine Isotope Stage 18 glacial. This anomalous situation was caused by nearly-continuous moisture supply from both oceans and its transport to higher latitudes through the westerlies, likely fuelling the accelerated expansion of northern hemisphere ice-sheets during the late MPT.
(Nature Communications. vol. 14, n° 2041-1723, pp. 2700, 10/05/2023)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Mission Tara Microplastics: a holistic set of protocols and data resources for the field investigation of plastic pollution along the land-sea continuum in Europe
The Tara Microplastics mission was conducted for 7 months to investigate plastic pollution along nine major rivers in Europe-Thames, Elbe, Rhine, Seine, Loire, Garonne, Ebro, Rhone, and Tiber. An extensive suite of sampling protocols was applied at four to five sites on each river along a salinity gradient from the sea and the outer estuary to downstream and upstream of the first heavily populated city. Biophysicochemical parameters including salinity, temperature, irradiance, particulate matter, large and small microplastics (MPs) concentration and composition, prokaryote and microeukaryote richness, and diversity on MPs and in the surrounding waters were routinely measured onboard the French research vessel Tara or from a semi-rigid boat in shallow waters. In addition, macroplastic and microplastic concentrations and composition were determined on river banks and beaches. Finally, cages containing either pristine pieces of plastics in the form of films or granules, and others containing mussels were immersed at each sampling site, 1 month prior to sampling in order to study the metabolic activity of the plastisphere by meta-OMICS and to run toxicity tests and pollutants analyses. Here, we fully described the holistic set of protocols designed for the Mission Tara Microplastics and promoted standard procedures to achieve its ambitious goals: (1) compare traits of plastic pollution among European rivers, (2) provide a baseline of the state of plastic pollution in the Anthropocene, (3) predict their evolution in the frame of the current European initiatives, (4) shed light on the toxicological effects of plastic on aquatic life, (5) model the transport of microplastics from land towards the sea, and (6) investigate the potential impact of pathogen or invasive species rafting on drifting plastics from the land to the sea through riverine systems.
(Environmental Science and Pollution Research, n° 0944-1344, 04/05/2023)
LOMIC, INSU - CNRS, SU, CNRS, OOB, SU, CNRS, UMR 8030, GENOSCOPE, DRF (CEA), CEA, UEVE, CNRS, IRDL, ENIB, UBO EPE, Bretagne INP, UBS, UBO EPE, ENSTA Bretagne, CNRS, LUBEM, UBO EPE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ICCF, INC-CNRS, CNRS, UCA, INP Clermont Auvergne, UCA, LECOB, SU, CNRS, OOB, SU, CNRS, ESRF, CEFREM, UPVD, INSU - CNRS, CNRS, OOB, SU, CNRS, LEMAR, IRD, IFREMER, UBO EPE, CNRS, EMBL-EBI, IMRCP, ICT, IRD, UT3, Comue de Toulouse, INC-CNRS, CNRS, Toulouse INP, Comue de Toulouse, INEE-CNRS, CNRS, UT3, Comue de Toulouse, INC-CNRS, CNRS, Softmat, ICT, IRD, UT3, Comue de Toulouse, INC-CNRS, CNRS, Toulouse INP, Comue de Toulouse, INEE-CNRS, CNRS, UT3, Comue de Toulouse, INC-CNRS, CNRS, SMODD, Softmat, ICT, IRD, UT3, INC-CNRS, CNRS, Toulouse INP, INEE-CNRS, CNRS, UT3, Comue de Toulouse, INC-CNRS, CNRS, IBMP, UNISTRA, CNRS, AIM (UMR7158 / UMR_E_9005 / UM_112), CEA, INSU - CNRS, UPD7, CNRS, CHU Bordeaux, IRSL, UPCité, HEGP, AP-HP, HUPO, UPD5 Médecine, UPD5, SGN, SBiK-F, LG / WGL, UBO EPE, IFREMER, IMRCP - SMODD, IMRCP, ICT, IRD, UT3, INC-CNRS, CNRS, Toulouse INP, INEE-CNRS, CNRS, UT3, Comue de Toulouse, INC-CNRS, CNRS, UNITO, LOV, INSU - CNRS, SU, CNRS, IMEV, INSU - CNRS, SU, CNRS, IUF, M.E.N.E.S.R., STCP, DTN, IRESNE, CEA
Atlantic circulation changes across a stadial–interstadial transition
Abstract. We combine consistently dated benthic carbon isotopic records distributed over the entire Atlantic Ocean with numerical simulations performed by a glacial configuration of the Norwegian Earth System Model with active ocean biogeochemistry in order to interpret the observed Cibicides δ13C changes at the stadial–interstadial transition corresponding to the end of Heinrich Stadial 4 (HS4) in terms of ocean circulation and remineralization changes. We show that the marked increase in Cibicides δ13C observed at the end of HS4 between ∼2000 and 4200 m in the Atlantic can be explained by changes in nutrient concentrations as simulated by the model in response to the halting of freshwater input in the high-latitude glacial North Atlantic. Our model results show that this Cibicides δ13C signal is associated with changes in the ratio of southern-sourced (SSW) versus northern-sourced (NSW) water masses at the core sites, whereby SSW is replaced by NSW as a consequence of the resumption of deep-water formation in the northern North Atlantic and Nordic Seas after the freshwater input is halted. Our results further suggest that the contribution of ocean circulation changes to this signal increases from ∼40 % at 2000 m to ∼80 % at 4000 m. Below ∼4200 m, the model shows little ocean circulation change but an increase in remineralization across the transition marking the end of HS4. The simulated lower remineralization during stadials compared to during interstadials is particularly pronounced in deep subantarctic sites, in agreement with the decrease in the export production of carbon to the deep Southern Ocean during stadials found in previous studies.
(Climate of the Past. vol. 19, n° 1814-9324, pp. 901-913, 04/05/2023)
LOCEAN-PROTEO, LOCEAN, MNHN, IRD, INSU - CNRS, SU, CNRS, IPSL (FR_636), ENS-PSL, UVSQ, CEA, INSU - CNRS, X, CNES, SU, CNRS, UPCité, BCCR, BIO / UiB, UiB, UiB, GEO-OCEAN, UBS, IFREMER, INSU - CNRS, UBO EPE, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IUEM, IRD, INSU - CNRS, UBO EPE, CNRS, SHOM, IGME, LNEG
Immunotoxicological effects of perfluorooctanesulfonic acid on European seabass are reduced by polyethylene microplastics
Marine environments receive plastic waste, where it suffers a transformation process into smaller particles. Among them, microplastics (MPs; <5 mm) are ingested by aquatic organisms leading to negative effects on animal welfare. The interactions between MPs, contaminants and organisms are poorly understood. To clarify this issue, European seabass (Dicentrarchus labrax L.) were fed with diets supplemented with 0 (control), polyethylene (PE) MPs (100 mg/kg diet), perfluorooctanesulfonic acid (PFOS, 4.83 μg/kg diet) or PFOS adsorbed to MPs (MPs-PFOS; final concentrations of 4.83 μg and 100 mg of PFOS and MP per kg of feed, respectively). Samples of skin mucus, serum, head-kidney (HK), liver, muscle, brain and intestine were obtained. PFOS levels were high in the liver of fish fed with the PFOS-diet, and markedly reduced when adsorbed to MPs. Compared to the control groups, liver EROD activity did not show any significant changes, whereas brain and muscle cholinesterase activities were decreased in all the groups. The histological and morphometrical study on liver and intestine showed significant alterations in fish fed with the experimental diets. At functional level, all the experimental diets affected the humoral (peroxidase, IgM, protease and bactericidal activities) as well as cellular (phagocytosis, respiratory burst and peroxidase) activities of HK leukocytes, being more marked those effects caused by the PFOS diet. Besides, treatments produced inflammation and oxidative stress as evidenced at gene level. Principal component analysis demonstrated that seabass fed with MPs-PFOS showed more similar effects to MPs alone than to PFOS. Overall, seabass fed with MPs-PFOS diet showed similar or lower toxicological alterations than those fed with MPs or PFOS alone demonstrating the lack of additive effects or even protection against PFOS toxicity.
(Fish and Shellfish Immunology. vol. 137, n° 1050-4648, pp. 108793, 03/05/2023)
RiverLy, INRAE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Low-Density Plastic Debris Dispersion beneath the Mediterranean Sea Surface
Plastic is a widespread marine pollutant, with most studies focusing on the distribution of floating plastic debris at the sea surface. Recent evidence, however, indicates a significant presence of such low density plastic in the water column and at the seafloor, but information on its origin and dispersion is lacking. Here, we studied the pathways and fate of sinking plastic debris in the Mediterranean Sea, one of the most polluted world seas. We used a recent Lagrangian plastic-tracking model, forced with realistic parameters, including a maximum estimated sinking speed of 7.8 m/d. Our simulations showed that the locations where particles left the surface differed significantly from those where they reached the seafloor, with lateral transport distances between 119 and 282 km. Furthermore, 60% of particles deposited on the bottom coastal strip (20 km wide) were released from vessels, 20% from the facing country, and 20% from other countries. Theoretical considerations furthermore suggested that biological activities potentially responsible for the sinking of low density plastic occur throughout the water column. Our findings indicate that the responsibility for seafloor plastic pollution is shared among Mediterranean countries, with potential impact on pelagic and benthic biota.
(Environmental Science and Technology, n° 0013-936X, 01/05/2023)
LOV, INSU - CNRS, SU, CNRS, IMEV, INSU - CNRS, SU, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Two new species of Marphysa (Annelida, Eunicidae) from southern Australia.
Two new species of Marphysa Quatrefages, 1866 are described from the southeast coast of Australia. With the presence of only compound spinigers and the branchiae present over many chaetigers, Marphysa baudini n. sp. belongs to the Sanguinea-group. This species has ventral cirri with an inflated base and digitiform tip and thick and wide anodont pectinate chaetae, with 3–5 internal long and thick teeth. With the presence of only compound falcigers, Marphysa davidattenboroughi n. sp., belongs to the “Aenea-group”. This species is characterised by the presence of a bilobed prostomium, a single pair of pygidial cirri and by the presence of thick, and wide anodont pectinate chaetae with 4–6 long internal and thick teeth.
(Zootaxa. vol. 5277, n° 1175-5326, pp. 113-130, 01/05/2023)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Volcanic, tectonic and climate controls on lacustrine sedimentary supplies over the last millenia in NE Chilean Patagonia (Lake Esponja, Aysen, 45°S)
The environmental variability of Northern Chilean Patagonia during the last millennia is evaluated using a multi-proxy analysis of sediment cores from Lake Esponja (45°S 72°W) to decipher if the sediment deposition is controlled by volcanic eruptions, landslides induced by earthquake or heavy rainfall. The lake is located in a glacio-tectonic valley in Patagonia. The organic-rich clayey silt sediment with low biogenic silica content was analysed for grain size, magnetic susceptibility, organic matter, biogenic silica content and diatom assemblages, mineralogy (X-ray diffraction), organic (IRMS C and N analyses) and inorganic (XRF core-scanner) geochemistry and glass shard major composition (Microprobe, SEM). The combination of 210 Pb, 137 Cs, 14 C and tephrochronology indicates an averaged accumulation rate of 0.4 mm/year, leading to a record of ~3.5 kyr within 154 cm. The sedimentary geochemistry records changes in volcanic supplies, diatom productivity and detrital inputs. The sediments were interrupted by millimetric to centimetric layers corresponding to tephra deposition related to explosive eruptions of nearby volcanoes Macá, Melimoyu and Hudson. Concerning the diatoms, the dominant planktonic species (80–150 cm) are replaced by benthic species in a transition interval (55–80 cm) and then by Surirella spp. in the upper core. This last genus indicates a closure of the basin ~2 ka ago, probably related to an uplift linked to a rejuvenation of the Mañihuales fault. This local change could reflect regional tectonic instability. Indeed, a partial earthquake rupture occurred around ~AD100 along the southern part of the Valdivia segment, recorded as a mass transport deposit in Aysén fjord sedimentation. The fine detrital input varies over time with more variable Si/Al values in the lower part of the LEs14 core than in the upper 80 cm. The higher values may reflect wetter conditions, leading to an higher lake level and more turbid conditions in agreement with changes in diatom assemblages.
(The Holocene. vol. 33, n° 0959-6836, pp. 518-535, 01/05/2023)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Synergic role of frontal migration and silicic acid concentration in driving diatom productivity in the Indian sector of the Southern Ocean over the past 350 ka
(Marine Micropaleontology. vol. 181, n° 0377-8398, pp. 102245, 01/05/2023)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Silver origins and spatial distribution in soils of southwestern France: A first assessment with cokriging
Ag is a rare, non-essential metal with many applications in different forms, including nanoparticles (Ag-NPs). Its release into the soil environment can represent a risk, due to the toxicity of silver. This study is based on the analysis of samples from the two sampling campaigns of the Soil Quality Measurement Network, RMQS1 and RMQS2, to establish the spatial distribution and origin of Ag in the soils of southwestern France (area of 90,293 km2). Given the progress of the second campaign (completion in 2027), we chose to do a cokriging to estimate the spatial distribution, with Pb, Cd or Cu as potential secondary variables. The results of the analyzes of the 35 samples of the RMQS2 indicate a range of Ag concentration in the soils going from 0.015 to 0.222 mg kg−1 and a median of 0.081 mg kg−1. Correlations were found between the concentrations of Ag Cd, Cu and Pb, and also between Ag concentrations and distance to Pb mines and deposits (r = 0.62). This suggests a common origin for Ag and Pb linked to historical exploitations of argentiferous galena. No link could be demonstrated between the concentration of Ag and the high density of anti-hail ground generators in the region. The analysis of the (auto-)variograms showed that Pb is the most relevant variable compared to Cd and Cu to achieve a cokriging. Thus, based on Ag concentrations from RMQS2 and Pb concentrations from RMQS1 (356 samples), a linear co-regionalization model was established and the co-kriging of Ag concentrations in soils calculated. Compared to ordinary kriging, cokriging improved the quality of the interpolation (decrease in the root mean square error).
(CATENA. vol. 224, n° 0341-8162, pp. 106992, 01/05/2023)
Bordeaux Sciences Agro, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IPREM, UPPA, INC-CNRS, CNRS