How does the bopyrid isopod Gyge branchialis interfere with trace metal bioaccumulation in the mud shrimp Upogebia cf. pusilla?
Parasites are widespread in natural environments, and their impacts on the fitness of their host and, at a broader scale, on ecosystem functioning are well recognized. Over the last two decades, there has been an increasing interest in the effects of parasites in conjunction with other stressors, especially pollutants, on the health of organisms. For instance, parasites can interfere with the bioaccumulation process of contaminants in their host leading to parasitized organisms exhibiting lower pollutants burdens than unparasitized individuals for example. However, the mechanisms underlying these patterns are not well understood. This study examined how the bopyrid parasite Gyge branchialis could lower the cadmium (Cd) uptake of its mud shrimp host Upogebia cf. pusilla. When exposed to water-borne Cd, parasites were able to bioaccumulate this trace metal. However, the uptake of Cd by the parasite was low and cannot entirely explain the deficit of Cd contamination of the host. The weight of gills of parasitized organisms was significantly reduced compared with unparasitized organisms. We suggest that by reducing the surface for metal uptake, parasites could lower the contaminant burden of their host.
(Parasitology Research. vol. 118, n° 0932-0113, pp. 363-367, 21/11/2018)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Exposure to microplastic: ingestion/egestion rates and behavioural impact on Solea solea
Microplastic (MP) occurrence is ubiquitous in fresh and marine waters and species living inEstuary are particularly exposed to this kind of pollution. In this context, the Seine River isinteresting for investigating the impacts of MP on fish, because of intense and numerous humanactivities through its watershed. The goal of this study is to evaluate the fate and impact of MPingestion using experimental exposure of the common sole, Solea solea, a representative species ofthe Seine Estuary. Larvae of fish (from 7 days post hatch (dph) to 42 dph) were exposed during 2hours to MP particles before (7 dph), during (21 and 22 dph) and after metamorphosis (41 and 42dph). Three types of industrial MP were chosen with different properties (middle size floating (27-35μg mL-1, DC: 50 ng mL-1). Post-exposurem, d=0.99), middle size sinking (27-32μg mL-1, DC: 50 ng mL-1). Post-exposurem, d=1.20) and large size sinking (63- 75μg mL-1, DC: 50 ng mL-1). Post-exposurem, d=1.20).In addition, at the last stage, fish were also exposed to natural plastic particles collected in the SeineRiver and ground into a fraction with a size less than 100 μg mL-1, DC: 50 ng mL-1). Post-exposurem (PVC, PE, PET, PS and PP testedseparately). After exposure, fish which had ingested MP were counted (Figure 1) and isolated tomonitor egestion. Solea solea ingested all types of plastics in variable (1 to more than 100)quantities and egested them on average less than 24 hours after exposure at all stages. A behaviouralchallenge, was performed on MP contaminated larvae. Behavioral responses of fish did not seem tobe affected by MP exposures before metamorphosis compared to controls but distance moveddecreased during metamorphosis for fish that had ingested MP particles. This could be explained bythe fact that before metamorphosis fish can still use yolk energy reserve and are thus less affected byMP than later on when external feeding becomes mandatory.
(pp. 359, 19/11/2018)
LRHLR, HGS, IFREMER, UB, BTSB, INUC, Comue de Toulouse, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UMR MARBEC, IRD, IFREMER, UM, CNRS
Contamination of marine sediments by microplastics and adsorbed organochlorine pollution (chlordecone) in coral reefs of Guadeloupe (Lesser Antilles)
(05/11/2018)
BOREA, UNICAEN, NU, MNHN, IRD, SU, CNRS, UA, LPTC, UB, CNRS, DYNECAR EA 926, UAG, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, ISM, UB, INC-CNRS, CNRS
New insights from microfauna associations characterizing palaeoenvironments, sea level fluctuations and a tsunami event along Sfax Northern coast (Gulf of Gabes, Tunisia) during the Late Pleistocene-Holocene
Late Pleistocene to Holocene evolution of the Northern coast of Sfax (Gulf of Gabes, Tunisia) is deduced on the basis of the analyses of sediment cores and coastal outcrops. The environmental changes are established by means of microfauna and mollusk assemblages and biocenotic parameters complemented by geochemical, sedimentological and correspondence analysis (CA). An opened embayment, rich in warm Senegalese fauna, allowed the deposition of quartz-rich sands Late Pleistocene in age. During the Late Holocene, a major modification of the environmental characters is recognized. The dominance of marine ostracod and coastal foraminifera coupled with high values of species richness characterize a widely opened lagoon. This lagoon is subjected to the action of the alongshore drifts which are responsible for the build-up of sand spits and the genesis of the present sebkhas. Two transgressive events, overlying the marine Late Pleistocene quartz-rich sands, are dated at 2018–2419 and 1001–1804 a cal BP. The dominance of marine and coastal foraminifera, the recurrence of ostracods and the high values of biocenotic parameters testify these two events. Sudden changes, toward 0–502 a cal BP, in the structure of populations, geochemical element concentrations and sedimentological trend argue in favor of a tsunami event and the settlement of peculiar environment. The latter records (1) the reworking of Holocene microfauna and Tyrrhenian sands rich in mollusks eroded from the marine substrata; (2) the high concentration of poorly stratified and poorly sorted shells; (3) fining-upward and thinning landward sequences; (4) the dominance of articulated bivalves and sharpened shells; and (5) the locally extensive deposits up to 160 m inland rising in altitude of about 0.75 m. This extreme event can be correlated with the tsunami generated by the strong earthquake, 1908 AD in age, in Eastern Sicily or by one of the earthquakes recorded during the 18th Century around the Mediterranean basin such as Sfax earthquake of 1750 AD.
(Journal of African Earth Sciences. vol. 147, n° 1464-343X, pp. 411-429, 01/11/2018)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Concentrations and morphology of microplastics in the Seine river estuary
(01/11/2018)
LEESU, ENPC, UPEC UP12, LERN, COAST, IFREMER, LANIE, SEARS, DPC, CEA-DES (ex-DEN), IFREMER, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
What is the relationship between the bioaccumulation of chemical contaminants in the variegated scallop Mimachlamys varia and its health status? A study carried out on the French Atlantic coast using the Path ComDim model
Increasing activity along the French Atlantic coast has led to chronic pollution with, in particular, mixtures of contaminants such as hydrocarbons, phytosanitary products, PCBs and heavy metals. Based on previous research, pollution biomarkers were used in this study as they can indicate health status when monitoring the impact of pollutants on coastal species such as the marine bivalve Mimachlamys varia. Mollusc bivalves were sampled in March 2016, in open and semi-open areas (a harbour zone), from thirteen sites which differed in terms of their level of pollution, and were located along the Atlantic coast from Brittany down to the Nouvelle-Aquitaine region. First, analyses of heavy metals and organic contaminants (e.g. pesticides, polycyclic aromatic hydrocarbons, polychlorobiphenyl) in the digestive gland of bivalves were performed. Second, biochemical assays were used to study defence biomarkers: oxidative stress with Superoxide Dismutase (SOD), detoxification of organic compounds with Glutathione-S Transferase (GST), lipid peroxidation with Malondialdehyde (MDA), and immune processes with Laccase. In addition to the biochemical assays, a genetic approach was used to measure genetic diversity (haplotype and nucleotide diversity) at each site. Biomarker assays and genetic diversity were correlated with the chemical contaminants in bivalves using the Path-ComDim statistical model. Our results showed specific correlations between biochemical assays in the digestive glands with heavy metal contaminants, and between genetic diversity and organic pollution. Blocks of responses were analysed for correlations in order to develop standardized tools and guidelines that could improve our understanding of the short-term and long-term impact of contaminants on physiological parameters.
(Science of the Total Environment. vol. 640-641, n° 0048-9697, pp. 662 - 670, 01/11/2018)
LIENSs, INSU - CNRS, ULR, CNRS, ONIRIS, StatSC, ONIRIS, INRAE, Cedre, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Do trace metal contamination and parasitism influence the activities of the bioturbating mud shrimp Upogebia cf. pusilla?
(Aquatic Toxicology. vol. 204, n° 0166-445X, pp. 46-58, 01/11/2018)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LEFE, INEE-CNRS, CNRS, UT3, Comue de Toulouse, CNRS, Toulouse INP, Comue de Toulouse, LOBB, OOB, UPMC, CNRS, UPMC, INSU - CNRS, CNRS
A reduced-complexity shoreline change model combining longshore and cross-shore processes: The LX-Shore model
A reduced-complexity numerical model, LX-Shore, is developed to simulate shoreline evolution along wave-dominated sandy coasts. The model can handle any sandy shoreline geometries (e.g. sand spits, islands), including non-erodible areas such as coastal defenses and headlands, and is coupled with a spectral wave model to cope with complex nearshore wave fields. Shoreline change is primarily driven by the gradients in total longshore sediment transport and by the cross-shore transport owing to variability in incident wave energy. Application to academic cases and a real coast highlights the potential of LX-Shore to simulate shoreline change on timescales from hours (storm) to decades with low computational cost. LX-Shore opens new perspectives in terms of knowledge on the primary mechanisms locally driving shoreline change and for ensemble-based simulations of future shoreline evolution.
(Environmental Modelling and Software. vol. 109, n° 1364-8152, pp. 1-16, 01/11/2018)
BRGM, UB, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Compiling multiproxy quantitative hydrographic data from Holocene marine archives in the North Atlantic: A way to decipher oceanic and climatic dynamics and natural modes?
This paper illustrates a new compilation of sea-surface hydrographic data (SST mainly) derived from multiproxy reconstructions on high time-resolution (decadal to centennial) marine archives. This compilation is focussed on the boreal Atlantic and gathers Holocene sedimentological records (defining the HAMOC database) which were retrieved in the vicinity of the subpolar and subtropical oceanic gyres. It provides for the first time a 12 ka long and multi-sourced (i.e. from different ecological groups) document of the evolution of sea-surface parameters over the North Atlantic, highlighting common regional trends but also discrepancies which need to be considered and integrated to further understand the Atlantic circulation dynamics and related climatic modes. Selective records have been extracted from the database and their significance tested considering proxy-dependent responses. This sheds light on the importance of intrinsic meaning carried by each proxies, often misconsidered and eluded while they typify critical ecological changes (living depth, seasonality of blooms, ect). To disentangle those changes is not easy and implies integrating artefacts linked both to ecological adaptations and environmental shifts (themselves being nested), but needs urgently to be considered in future works as it is the only way to progress in our knowledges of the (living) ocean resilience to climate hazards.
(Global and Planetary Change. vol. 170, n° 0921-8181, pp. 48-61, 01/11/2018)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, CERFACS, GEOPS, UP11, CNRS
Multi-centennial variability of the AMOC over the Holocene: A new reconstruction based on multiple proxy-derived SST records
The Meridional Overturning Circulation (AMOC) is believed to have played a key role in climate variability over the Holocene, but the reconstruction of its variations remains limited by inconsistencies among different proxy records used. To circumvent this issue, we propose a new statistical method to reconstruct the AMOC variations based on multiple sources of information, i.e. 22 proxy records of annual Sea Surface Temperature (SST) compiled in the North Atlantic and covering the Holocene (HAMOC database). Our approach consists of isolating the main variability modes hidden in the Atlantic Ocean through principal component analysis (PCA) and then evaluating their link with the AMOC. To estimate the skill of our method, we use a pseudo-proxy approach applied to observational SST data covering the period 1870–2010, as well as simulations from a comprehensive climate model (IPSL-CM5A-LR) where the AMOC variations are known. In instrumental observations and most of the model simulations, the first mode of SST variations from the PCA analysis over the North Atlantic can be related with the external radiative forcing, while the second mode is reminiscent of the AMOC variability and of its signature on SST. When computed over the Holocene period using the HAMOC database, the first mode is indeed well correlated with the insolation changes, marked by a general cooling of the Northern Atlantic from 9 thousand years ago (ka). The second mode, that we consider here as a reconstruction of standardized AMOC variations following the pseudo-proxy analysis in the model simulations and in the observations, is in general agreement with a few independent reconstructions of the deep branch of the AMOC recorded in the North Atlantic. Based on this new AMOC index reconstruction, we highlight that the Early Holocene may have been associated with an AMOC enhancement, followed by a general weakening trend from around 6–7 ka up to 2 ka, in line with the major hydro-dynamical re-organization which occurred in the North Atlantic from the mid-Holocene period. We find that the late Holocene period is marked by two fluctuations, with maxima at about 4.2 and 5 ka, in line with short-term variations identified in proxy records of the velocity of the Greenland-Iceland-Scotland overflow waters.
(Global and Planetary Change. vol. 170, n° 0921-8181, pp. 172 - 189, 01/11/2018)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, GEOPS, UP11, CNRS