Contribution of high resolution spatial remote sensing for the study of surface water cycles and suspended particulate matter along the watershed-coastal ocean continuum
The anticipation and adaptation of our societies to the upheavals resulting from climate change are today major issues guiding human activities and public action. Nevertheless, the forecast remains a key challenge because of the strong uncertainties that exist and it is essential to continue to progress in understanding the mechanisms behind these upheavals. Within the hydrological cycle, the surface reservoir (including lakes, rivers and floodplains) occupies an important place as it is one of the main water resources of ecosystems and populations. However, the dynamics of surface water stocks are still poorly known at the regional and global scales, due to the absence of multi-year measures of extension and water depth of the flooded areas, and the limited consideration of these variables in hydrological and hydrodynamic models. Satellite remote sensing now offers the possibility of monitoring surface water stocks by using the complementarity between multispectral imagery, allowing to map flooded areas, and the radar altimetry providing time series of water depths of continental hydro systems. The aim of my thesis is to make the most of the complementarity between the different types of spatial observations to evaluate the water resources of the surface reservoir and to measure the dynamics of water transfers between land and ocean, and its impact on the coastal zone using suspended particulate matter as tracer of water bodies. Since the mid-1990s, the multiplication of multispectral missions with medium resolution (<1 km of spatial resolution) and high-precision radar altimeters (between 10 and 30 cm) makes it possible to carry out weekly-to-monthly monitoring of volumes surface water in large river basins.
(17/09/2019)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Microplastic contamination of sediment and water column in the Seine River Estuary
Nowadays, microplastic (MPs) pollution is well documented in marine ecosystems since the first publication alarming about marine plastic pollution in 1972 [1]. Similarly, continental contamination is more and more investigated. More recently, interest for estuarine systems is growing. Estuaries are considered as a suspected predominant pathway for microplastic pollution from continent to oceans. The specific conditions of estuaries, like salinity gradient, tides and hydrodynamics, could affect the repartition, settling and transfer of microplastics to marine systems.
(pp. p. 4-9, 16/09/2019)
LEESU, ENPC, UPEC UP12, IFREMER, LERN, COAST, IFREMER, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Biomagnification of perfluoroalkyl acids (PFAAs) in the food web of an urban river: assessment of the trophic transfer of targeted and unknown precursors and implications
(Environmental Science: Processes & Impacts, n° 2050-7887, 10/09/2019)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LPTC, UB, CNRS, DEEP, INSA Lyon, INSA, METIS, UPMC, EPHE, PSL, CNRS, METIS, EPHE, PSL, INSU - CNRS, SU, CNRS, ENTPE
Mediterranean Outflow Water and contourites over two analog climate cycles in the Gulf of Cadiz
The Contourite Depositional Systems (CDSs) in the Gulf of Cadiz are unique archives of the Mediterranean Outflow Water (MOW) variability since the opening of the Gibraltar gateway at the end of the Miocene (5.33 Ma). The construction of these systems involves the upper (MUW) and lower (MLW) branches of the MOW. Drilling of these CDSs during IODP Expedition 339 (2011-2012) enables to investigate the MOW dynamics over an extended time period of the late Cenozoic. This study is centered on the sedimentological and facies characteristics of contourite beds over two periods with similar astronomic configurations (MIS1-2 and MIS 11-12) in order to compare the behavior and circulation regime of the MOW over two contrasted climatic cycles and their associated deglaciation. Sedimentological and facies analysis of different CDSs in the Gulf of Cadiz are based on an extensive set of data including grain size, petrographic (?) analyses of sandy components and clay assemblages, thin sections of contourite sequences, XRF core-scanner data, natural gamma ray data and biostratigraphy based on planktonic foraminifers. The results show a different behavior of the MOW between MIS 1/2 and MIS 11/12. For instance, in the Faro Drift (upper MOW), MIS 11 is characterized by the presence of several fine grained contourites (silt/ fine sand) while they are rare during MIS 1. During MIS 2 and MIS 12, only one contourite bed is recorded. These time periods are also characterized by different types of contourite beds in terms of grain size and composition: some are carbonate-rich whereas others are enriched in siliciclastic/terrigenous or/and authigenic particles. Different patterns of component evolution are also observed showing both changes in MOW velocity and availability of different sources of sediment involved.
(10/09/2019)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LOG, INSU - CNRS, ULCO, CNRS, IRD [Ile-de-France], ITPA, SoMAS, SBU, SUNY
Laticorophium baconi (Shoemaker, 1934) (Crustacea: Amphipoda: Corophiidae: Corophiini): first record in European marine waters
Laticorophium baconi (Amphipoda, Corophiidae) was recorded for the first time in European marine waters from buoy fouling communities at the Sant Carles de la Ràpita marina (Alfacs Bay, Eastern Mediterranean Spanish coast). Presence of juveniles, adult males, brooding and ovigerous females were indicative of a well-established population. An entire description of the species, together with a dichotomous key to Corophiini genera characterized by urosome segments fused with uropod 1 ventrally inserted, are provided. This record supports the view that L. baconi may have been overlooked and/or potentially confused with otherCorophiini species such as Apocorophium acutum in previous studies
(BioInvasions Records. vol. 8, n° 2242-1300, pp. 848-861, 04/09/2019)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UB, LIENSs, INSU - CNRS, ULR, CNRS
A revision of the French Trichobranchidae (Polychaeta), with descriptions of nine new species
Trichobranchidae from French waters are revised based on material available in French marine stations and newly collected specimens. This research is the first part of the “Spaghetti Project” aiming to revise French species of terebellids and trichobranchids. It confirms the absence of the so-called cosmopolitan species Terebellides stroemii from French waters, and describes eight new species of Terebellides: T. bonifi n. sp., T. ceneresi n. sp., T. europaea n. sp., T. gentili n. sp., T. gralli n. sp., T. lilasae n. sp., T. parapari n. sp. and T. resomari n. sp. and one species of Trichobranchus: T. demontaudouini n. sp. using both morphological and molecular tools. An identification key for all European species of Trichobranchidae is provided.
(Zootaxa. vol. 4664, n° 1175-5326, pp. 151-190, 03/09/2019)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
PaCTS 1.0: A Crowdsourced Reporting Standard for Paleoclimate Data
The progress of science is tied to the standardization of measurements, instruments, and data. This is especially true in the Big Data age, where analyzing large data volumes critically hinges on the data being standardized. Accordingly, the lack of community‐sanctioned data standards in paleoclimatology has largely precluded the benefits of Big Data advances in the field. Building upon recent efforts to standardize the format and terminology of paleoclimate data, this article describes the Paleoclimate Community reporTing Standard (PaCTS), a crowdsourced reporting standard for such data. PaCTS captures which information should be included when reporting paleoclimate data, with the goal of maximizing the reuse value of paleoclimate data sets, particularly for synthesis work and comparison to climate model simulations. Initiated by the LinkedEarth project, the process to elicit a reporting standard involved an international workshop in 2016, various forms of digital community engagement over the next few years, and grassroots working groups. Participants in this process identified important properties across paleoclimate archives, in addition to the reporting of uncertainties and chronologies; they also identified archive‐specific properties and distinguished reporting standards for new versus legacy data sets. This work shows that at least 135 respondents overwhelmingly support a drastic increase in the amount of metadata accompanying paleoclimate data sets. Since such goals are at odds with present practices, we discuss a transparent path toward implementing or revising these recommendations in the near future, using both bottom‐up and top‐down approaches.
(Paleoceanography and Paleoclimatology. vol. 34, n° 2572-4525, pp. 1570-1596, 03/09/2019)
GERICS, GKSS, NPL, UNIL, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, INRS - ETE, INRS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, PALEOCEAN, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, EDYTEM, USMB [Université de Savoie] [Université de Chambéry], CNRS, Fédération OSUG, M2C, UNICAEN, NU, INSU - CNRS, UNIROUEN, NU, CNRS, UMR GESTE, ENGEES, IRSTEA, UMR ISEM, Cirad, EPHE, PSL, UM, CNRS, ASU, CTCPA, CHUV, ETHZ, ETH Zürich, LEFE, INEE-CNRS, CNRS, UT3, Comue de Toulouse, CNRS, Toulouse INP, Comue de Toulouse, OU, UNSW, AWI
The coccolithophore family Calciosoleniaceae with report of a new species: Calciosolenia subtropicus from the southern Indian Ocean
The families Calciosoleniaceae, Syracosphaeraceae and Rhabdosphaeraceae belong to the order Syracosphaerales and constitute a significant component of extant coccolithophore species, sharing similar ultrastructural bauplans. The literature on Calciosoleniaceae is reviewed and combined light-and scanning electron microscope studies of four extant species including Calciosolenia subtropicus sp. nov. described herein, reveal the unique interpretative V/R structure of the Calciosoleniaceae. Calciosolenia subtropicus sp. nov. is primarily distinguished from previously well documented extant species, Calciosolenia murrayi, Calciosolenia brasiliensis and Calciosolenia corsellii, by the consistent presence of prominent clockwise imbricated wedge shaped R-elements at the inner margin and in distal view of both ordinary and apical scapholiths, distinctly tapering in size towards the major axis of the scapholiths, as observed under the scanning electron microscope. Prompted by the contrasting birefringence displayed by the rim, central area, apical and ordinary coccoliths under crossed-polarized illumination in earlier publications, the Energy Dispersive Spectrometry of Calciosolenia subtropicus sp. nov. reveals the presence of (a) calcite + high silica in the ordinary coccoliths showing dark appearance and (b) high calcite + negligible silica in the apical coccoliths showing bright appearance; besides the c-axis orientation of calcite, the different elemental composition of coccoliths seems to control birefringence. Molecular genetic studies are necessary to provide insight on the relationship between the Calciosoleniaceae and other coccolithophore families including reasons for its successful invasion in contrasting ecological regimes.
(Micropaleontology, n° 0026-2803, 02/09/2019)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Temporal evolution of the coastal upwelling in the eastern boundary currents from the Pacific and Atlantic oceans since the 18th century
Coastal upwelling systems, such as the Peru and the Canary Current Systems, are among the most productive ecosystems in the global ocean. Several observations and numerical models suggest that primary productivity declined over the past a few decades, and will to continue during the next century due to the impact of global warming. However, if at a global scale, a warming of the ocean surface is observed since the beginning of the industrial era, at a regional scale, the surface waters in the upwelling zones indicate, on the contrary, a cooling. To explain this occurrence, Bakun (1990) hypothesized that global warming increases the land-sea temperature gradients which in turn increase the alongshore winds favorable to upwelling. Although the driving mechanism is still the subject of debate, most experimental and numerical models studies indicate that coastal upwelling has intensified in recent years and the trend is toward further increases. However, there are very few studies that go beyond the 20th century. To make up for this lack of data, here, we present new data from high-resolution sediment cores covering the last two centuries and cored off the Peru and Senegal coasts. We used alkenones to reconstruct Sea Surface Temperature (SST); Total Organic Carbon (TOC) as proxy of surface productivity and granulometric parameters as a proxy of transport of terrigenous material. Our results indicate a systematic cooling developing over the last century ranging from 0.5 to 1°C off Peru. In contrast, sea surface waters withn the Canary current system exhibit warming at latitude lower than 20°N and a strong cooling at 31°N, with a marked steepening in the second part of the 20th century. There was also a close relationship between SST and TOC. In Peru and at 20°N off Senegal, cooling is coupled with an increase in TOC, suggesting an increase in surface productivity, while warming of the sea surface observed off the coast of Senegal at 31°N is parallel to a decrease in TOC. Preliminary data from the Pacific Ocean upwelling indicate complex covariance between SSTs and the silts content fraction.
(02/09/2019)
LOCEAN-VOG, LOCEAN, MNHN, IRD, INSU - CNRS, SU, CNRS, IPSL (FR_636), ENS-PSL, UVSQ, CEA, INSU - CNRS, X, CNES, SU, CNRS, UPCité, CR2P, MNHN, SU, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IPH, CNRS, iSTeP, INSU - CNRS, SU, CNRS, LOCEAN-CYBIOM, LOCEAN, MNHN, IRD, INSU - CNRS, SU, CNRS, IPSL (FR_636), ENS-PSL, UVSQ, CEA, INSU - CNRS, X, CNES, SU, CNRS, UPCité
The Diversity of Benthic Diatoms Affects Ecosystem Productivity in Heterogeneous Coastal Environments
The current decrease in biodiversity affects all ecosystems, and the impacts of diversity on ecosystem functioning need to be resolved. So far, marine studies about diversity–ecosystem productivity-relationships have concentrated on small-scale, controlled experiments, with often limited relevance to natural ecosystems. Here, we provide a real-world study on the effects of microorganismal diversity (measured as the diversity of benthic diatom communities) on ecosystem productivity (using chlorophyll a concentration as a surrogate) in a heterogeneous marine coastal archipelago. We collected 78 sediment cores at 17 sites in the northern Baltic Sea and found exceptionally high diatom diversity (328 observed species). We used structural equation models and quantile regression to explore relationships between diatom diversity and productivity. Previous studies have found contradictory results in the relationship between microorganismal diversity and ecosystem productivity, but we showed a linear and positive basal relationship between diatom diversity and productivity, which indicates that diatom diversity most likely forms the lowest boundary for productivity. Thus, although productivity can be high even when diatom diversity is low, high diatom diversity supports high productivity. The trait composition was more effective than taxonomical composition in showing such a relationship, which could be due to niche complementarity. Our results also indicated that environmental heterogeneity leads to substantial patchiness in the diversity of benthic diatom communities, mainly induced by the variation in sediment organic matter content. Therefore, future changes in precipitation and river runoff and associated changes in the quality and quantity of organic matter in the sea, will also affect diatom communities and, hence, ecosystem productivity. Our study suggests that benthic microorganisms are vital for ecosystem productivity, and together with the substantial heterogeneity of coastal ecosystems, they should be considered when evaluating the potential productivity of coastal areas.
(Ecology. vol. 100, n° 0012-9658, pp. e02765, 01/09/2019)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS