Dynamics of microbial communities across the three domains of life over an annual cycle with emphasis on marine mucilage in the Southern Bay of Biscay resolved by microbial fingerprinting
Marine mucilage has been described as worldwide phenomena occurring sporadically, or frequently in certain coastal areas. They are transitory phenomena that can remain in the photic zone for several days or weeks. Their occurrence has been more frequent and persistent, and their magnitude has increased during the last decades. Their formation typically reflects an imbalance in the marine microbial communities, and has frequently be linked to global changes. Recurrent marine mucilage events have been observed in recent years in the Southern Bay of Biscay near the French coast, mainly south of the Adour estuary. In this study, we used a fingerprinting method (T-RFLP) targeting 16S and 18S rRNA genes to investigate marine microbial community composition and dynamics over an annual cycle across the three domains of life in coastal water at three depths, in the Adour River upstream of the mouth and in the marine mucilage. In line with studies conducted in marine environments we highlighted that the dynamics of marine microbial communities in the Bay of Biscay coincided with two environmental contexts: winter and spring on one hand and summer and autumn on the other hand. More interestingly, this dynamics affects also the marine pelagic mucilage that was observed during the sampling campaigns. Thus, the composition of the marine mucilage that appears in winter/spring context diverges from the composition of the marine mucilage that occurred during the summer/autumn context. We highlighted also that marine microbial communities were partly different from marine mucilage communities with an enrichment of some microorganisms suggesting that marine mucilage behaves as a microhabitat in seawater and possesses distinct microbial assemblages from the surrounding communities.
(Continental Shelf Research. vol. 186, n° 0278-4343, pp. 127-137, 01/06/2019)
IPREM, UPPA, INC-CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, BOREA, UNICAEN, NU, MNHN, IRD, SU, CNRS, UA, ECOBIOP, INRA, UPPA
Imidacloprid induces adverse effects on fish early life stages that are more severe in Japanese medaka (Oryzias latipes) than in zebrafish (Danio rerio)
Neonicotinoids are widely used insecticides that have frequently been found in freshwater with concentrations ranging from ng to μg/L. It is known that these compounds impact non-target invertebrates, such as bees and gammaridae, in terms of toxicity and behavior, but impacts and species differences on vertebrates such as fish are little explored. The aim of this study was to investigate and compare the effects of one widely used neonicotinoid, imidacloprid, on development and behavior of two fish model species: Zebrafish (Danio rerio) and Japanese medaka (Oryzias latipes). Fish were exposed for 5 (zebrafish) and 14 (medaka) days from 0.2 to 2000 μg/L imidacloprid by aqueous exposure. Survival, development, behavior and histological features were monitored and organism-internal concentrations and biotransformation products measured. Imidacloprid caused sublethal effects in both species but the effects were much stronger in medaka with deformities, lesions and reduced growth being the most prominent impacts. Due to the overall longer time of development, time-integrated exposure of medaka was about 2-fold higher compared to zebrafish, potentially accounting for parts of the sensitivity differences. Our results underline the importance of taking species sensitivity differences into account especially when considering that medaka responded at imidacloprid concentrations that have been measured in the environment.
(Chemosphere. vol. 225, n° 0045-6535, pp. 470-478, 01/06/2019)
EAWAG, UniMe, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IBP, D-USYS, ETH Zürich, ENAC, EPFL
Investigation on the capabilities of low-cost and smartphone-based coastal imagery for deriving coastal state video indicators : applications on the upper mediterranean
This work deals with the implementation and operational use of low-cost and smartphone-based camera system for the purpose of coastal video monitoring. Capability of such system for coastal remote sensing is described in this study. Particularly, a small network of ©Solarcam has been implemented in Corsica Island (France) for purposes of coastline evolution, sandbar(s) detections and to investigate the influence of the Posidonia banquettes on morphological evolution. A new coastal indicator derived from video observation is presented. Furthermore, the second part deals with the description and application of image semantic segmentation procedures, developed in order to regionalize the main morphologies framed by web-cams. Such techniques can be apply for a range of applications: from shoreline evolution, sandbar(s) detection, algae identification and development of a warning system.
(27/05/2019)
BRGM, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
PLASTIC-Seine research project: Microplastic Flux and Impact on biota in the Seine estuary.
Microplastics (MP) pollution is of emerging concern. Although numerous studies were recently carried out on freshwater and biota contamination, studies focused on estuary ecosystems are scarce. Estuaries can indeed play a significant role in the transport and transfer of MP to the ocean and the estuarine hydrodynamics and salinity gradient can greatly affect both MP distribution and concentrations, as well as the occurrence and levels in biotic compartments. In this context, the Plastic-Seine project (2017-2020) involving six French laboratories was launched to study the occurrence and levels of MP in all compartments of the ecosystem of the Seine River estuary (France). The objectives are: i) to study the occurrence and levels of MP in the Seine estuary for abiotic compartments (water column and sediment), ii) to study the ingestion and levels of MP for seven emblematic species of the Seine estuary, i.e, the worm Hediste diversicolor, the copepod Eurytemora affinis, the mussel Mytulis edulis, the prawn Palaemon longirostris and 3 fish species Platichthys flesus, Solea solea and Dicentrarchus labrax and iii) to assess the potential impacts of MP exposure on biology traits, physiology and behavior of three species (Hediste diversicolor, Eurytemora affinis and Solea solea). Preliminary and main results are here presented and discussed. First results on abiotic compartements highlighted the presence of fibers and fragements in both the water colonn and sediments. Particles exhibited different forms depending on their origin and/or fragmentation. Most of particles were inferior to 1 mm and a high proportion of fragments and films was higlighted. Slight MP distribution changes were also observed between surface water and subsurface water. For the seven species, MP including fibers and fragements were found. The others analyses are in progress. For all species, a high variabilities between species and individuals was highligted. High presence of fragments were noticed for seabass and worms in comparison to other species. In the case of prawns, a large amount of MP and especially of fibers were also observed on the cuticle surface. Futher studies will investigate the potential impacts of MP exposure on biology traits, physiology, and behavior of three estuarine species and the MP trophic transfer to common sole’s food chain.
(26/05/2019)
LEESU, ENPC, UPEC UP12, BIOSSE, UCO, MMS, UM, UN UFR ST, UN, UFR SPB, UN, IFREMER, LERN, COAST, IFREMER, UMR MARBEC, IRD, IFREMER, UM, CNRS, LANIE, SEARS, DPC, CEA-DES (ex-DEN), LOG, INSU - CNRS, ULCO, CNRS, IRD [Ile-de-France], ULCO, SEBIO, INERIS, URCA, ULH, NU, URCA, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, EPOC
The Omega-3 Index of macrophytes to improve the assessment of the treatment performance of constructed wetlands receiving treated wastewater
The Omega-3 Index of macrophytes to improve the assessment of the treatment performance of constructed wetlands receiving treated wastewater.
(pp. 1, 26/05/2019)
CNRS, UR REVERSAAL, IRSTEA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IRSTEA
First record of the non-indigenous Isopoda Synidotea laticauda Benedict, 1897 in the Seine Estuary (Normandy, France)
The northeastern Pacific isopod Synidotea laticauda Benedict, 1897 is reported for the first time in the French part of the English Channel. Specimens have been found in 2017 in a pebble habitat of the Seine Estuary (Normandy, France). Its occurrence in the Seine Estuary is probably related to international maritime traffic, which is important around the major seaports of the Seine Estuary: Le Havre and Rouen.
(An Aod - Les cahiers naturalistes de l’Observatoire marin. vol. 8, n° 2263-5718, pp. 11-20, 25/05/2019)
PatriNat, MNHN, CNRS, OFB, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CSLN, ULH, NU
Latitudinal variations in δ30Si and δ15N signatures along the Peruvian shelf: quantifying the effects of nutrient utilization versus denitrification over the past 600 years
Abstract. The stable sedimentary nitrogen isotope compositions of bulk organic matter (δ15Nbulk) and the silicon isotope composition of diatoms (δ30SiBSi) both mainly reflect the degree of past nutrient utilization by primary producers. However, in ocean areas where anoxic and suboxic conditions prevail, the δ15Nbulk signal ultimately recorded within the sediments is also influenced by water column denitrification, causing an increase in the subsurface δ15N signature of dissolved nitrate (δ15NO3-) upwelled to the surface. Such conditions are found in the oxygen minimum zone off the coast of Peru, where, at present, an increase in subsurface δ15NO3- from north to south along the shelf is observed due to ongoing denitrification within the poleward-flowing subsurface waters, while the δ30Si signature of silicic acid (δ30Si(OH)4) at the same time remains unchanged. Here, we present three new δ30SiBSi records between 11 and 15∘ S and compare these to previously published δ30SiBSi and δ15Nbulk records from Peru covering the past 600 years. We present a new approach to calculate past subsurface δ15NO3- signatures based on the direct comparison of δ30SiBSi and δ15Nbulk signatures at a latitudinal resolution for different time periods. Our results show that, during the Current Warm Period (CWP, since 1800 CE) and prior short-term arid events, source water δ15NO3- compositions have been close to modern values, increasing southward from 7 to 10 ‰ (between 11 and 15∘ S). In contrast, during the Little Ice Age (LIA) we calculate low δ15NO3- values between 6 ‰ and 7.5 ‰. Furthermore, the direct δ30SiBSi versus δ15Nbulk comparison also enables us to relate the short-term variability in both isotope compositions to changes in the ratio of nutrients (NO3-:Si(OH)4) taken up by different dominating phytoplankton groups (diatoms and non-siliceous phytoplankton) under the variable climatic conditions of the past 600 years. Accordingly, we estimate a shift from a 1:1 (or 1:2) ratio during the CWP and a 2:1 (up to 15:1) ratio during the LIA, associated with a shift from overall high nutrient utilization to NO3--dominated (and thus non-siliceous phytoplankton) utilization.
(Biogeosciences. vol. 16, n° 1726-4170, pp. 2163-2180, 23/05/2019)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Suivis pluriannuels des transferts verticaux de pesticides dans des sols de vallée alluviale en monoculture de maïs irrigué
(pp. 23p., 21/05/2019)
CA 09, UCLouvain, CRA Occitanie, GET, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNES, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, AGIR, Toulouse INP, Comue de Toulouse, INP - PURPAN, Toulouse INP, Comue de Toulouse, INRAE
Caractérisation géochimique des changements paléoenvironnementaux au cours de l’Évènement Océanique Anoxique 2 (~94 Ma) dans le Bassin Vocontien (SE France)
Le passage Cénomanien-Turonien (~94 Ma) au Crétacé supérieur est marqué par une période de diminution de la quantité d’O2 dans les sédiments et la colonne d’eau et de perturbations biogéochimiques appelé Évènement Océanique Anoxique 2 (OAE 2). Comme l’ensemble des OAEs du Crétacé, l’OAE 2 s’est mis en place dans un contexte d’augmentation de la concentration en CO2 dans les océans et l’atmosphère, interprétée comme d’origine volcanique. L’hétérogénéité des réponses à cette perturbation globale suggère que des paramètres environnementaux régionaux ou locaux ont contribué au scénario de mise en place et d’évolution de l’OAE 2. L’objectif cette thèse est ainsi de déterminer le rôle de ces mécanismes à différentes échelles spatiales. La démarche consiste en une comparaison des conditions biogéochimiques associées à l’OAE 2 dans un bassin épicontinental, comme le Bassin Vocontien (SE France), avec les bassins océaniques mondiaux. La comparaison de données de géochimie organique (TOC, HI vs. OI), inorganique (enrichissements en éléments majeurs et traces, spéciation du fer) et isotopique (δ13C, δ15N, δ34S) de deux coupes du Bassin Vocontien semble indiquer que l’augmentation de la quantité de CO2 et de sulfates dans le bassin, associée à l’activité d’une Grande Province Volcanique, fut le facteur déclencheur de l’OAE 2. Par ailleurs, les hétérogénéités des conditions d’oxygénation semblent être majoritairement associées aux configurations géométriques des bassins et au taux de renouvellement des leurs eaux profondes, mais aussi aux conditions de productivité primaire influencés par les cycles de nutriments, et enfin aux paramètres climatiques régionaux.
(13/05/2019)
ISTerre, IFSTTAR, INSU - CNRS, USMB [Université de Savoie] [Université de Chambéry], CNRS, UGA [2016-2019]
Coupled ocean and atmospheric changes during Greenland stadial 1 in southwestern Europe
Paleoclimate reconstructions suggest that the complex variability within the Greenland stadial 1 (GS-1) over western Europe was governed by coupled ocean and atmospheric changes. However, few works from the North Atlantic mid-latitudes document both the GS-1 onset and its termination, which are often considered as single abrupt transition events. Here, we present a direct comparison between marine (alkenone-based sea surface temperatures) and terrestrial (pollen) data, at very high resolution (28 years mean), from the southwestern Iberian shelf record D13882. Our results reveal a rather complex climatic period with internally changing conditions. The GS-1 onset (GS-1a: 12890-12720 yr BP) is marked by a progressive cooling and drying; GS-1b (12720-12390 yr BP) is the coldest and driest phase; GS-1c (12390-12030 yr BP) is marked by a progressive warming and increase in moisture conditions; GS-1 termination (GS-1d: 12030-11770 yr BP) is marked by rapid switches between cool wet, cold dry and cool wet conditions. Although hydroclimate response was very unsteady throughout the GS-1 and in particular during its termination phase, the persistence of an open temperate and Mediterranean forest in southwestern Iberia during the entire episode suggests that at least some moisture was delivered via the Westerlies. We propose coupled ocean and atmospheric mechanisms to reproduce these scenaria. Changes in the strength of the Atlantic Meridional Overturning Circulation (AMOC) as well as variations in the North Atlantic sea-ice growth have favoured the displacement of the polar jet stream's latitudinal position and contributed to a complex spatial pattern and strength of the Westerlies across western Europe.
(Quaternary Science Reviews. vol. 212, n° 0277-3791, pp. 108-120, 01/05/2019)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS