Observations on the relationship between the Antarctic coastal diatoms Thalassiosira antarctica Comber and Porosira glacialis (Grunow) Jørgensen and sea ice concentrations during the late Quaternary
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(Marine Micropaleontology. vol. 73, n° 0377-8398, pp. 14-25, 01/10/2009)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UP1, LOCEAN, IPSL, ENS-PSL, PSL, UVSQ, UPMC, CEA, INSU - CNRS, X, IP Paris, CNES, CNRS, MNHN, IRD, UPMC, INSU - CNRS, CNRS, VU
Improving estuarine net flux estimates for dissolved cadmium export at the annual timescale: Application to the Gironde Estuary
Dissolved Cd (Cd D) concentrations along the salinity gradient were measured in surface water of the Gironde Estuary during 15 cruises (2001-2007), covering a wide range of contrasting situations in terms of hydrology, turbidity and season. During all situations dissolved Cd concentrations displayed maximum values in the mid-salinity range, reflecting Cd addition by chloride-induced desorption and complexa-tion. The daily net Cd D fluxes from the Gironde Estuary to the coastal ocean were estimated using Boyle's method. Extrapolating Cd D concentrations in the high salinity range to the freshwater end member using a theoretical dilution line produced 15 theoretical Cd concentrations (Cd D 0), each representative of one distinct situation. The obtained Cd D 0 concentrations were relatively similar (w201 AE 28 ng L À1) when freshwater discharge Q was >500 m 3 s À1 (508 Q 2600 m 3 s À1), but were highly variable (340 AE 80 ng L À1 ; 247-490 ng L À1) for low discharge situations (169 Q 368 m 3 s À1). The respective daily Cd D net fluxes were 5-39 kg day À1 , mainly depending on freshwater discharge. As this observation invalidates the existing method of estimating annual Cd D net fluxes, we proposed an empirical model, using representative Cd D 0 values and daily freshwater discharges for the 2001-2007 period. Subsequent integration produced reliable Cd D net flux estimates for the Gironde Estuary at the annual timescale that ranged between 3.8-5.0 t a À1 in 2005 and 6.0-7.2 t a À1 in 2004, depending on freshwater discharge. Comparing Cd D net fluxes with the incoming Cd D fluxes suggested that the annual net Cd D addition in the Gironde Estuary ranged from 3.5 to 6.7 t a À1 , without any clear temporal trend during the past seven years. The annual Cd D net fluxes did not show a clearly decreasing trend in spite of an overall decrease by a factor w6 in Cd gross fluxes during the past decade. Furthermore, in six years out of seven (except 2003), the annual Cd D net fluxes even exceeded river borne total (dissolved þ particulate) gross Cd fluxes into the estuary. These observations were attributed to progressive Cd desorption from both suspended particles and bottom sediment during various sedimentation-resuspension cycles induced by tidal currents and/or continuous dredging (navigation channel) and diverse intra-estuarine sources (wet deposition, urban sources, and agriculture). Provided that gross fluxes remain stable over time, dissolved Cd exportation from the Gironde Estuary to the coastal ocean may remain at the present level for the coming decade and the estuarine sedimentary Cd stock is forecast to decrease slowly.
(Estuarine, Coastal and Shelf Science. vol. 84, n° 0272-7714, pp. 429-439, 01/10/2009)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Spatial patterns of association at local and regional scales in coastal sand dune communities
Questions: Are positive understorey-dominant associations important in physically severe dune communities and does the strength of positive associations vary with disturbance at the local scale and with stress at the regional scale? Do associational patterns observed at the neighbourhood scale predict diversity at higher scales? Location: Coastal sand dunes, Aquitaine (France). Methods: Associational patterns with five dominant species were recorded along a local gradient of disturbance and a 240-km long regional gradient. Density, richness, cover and variance ratio of understorey species were recorded in quadrats located in dominant and in open areas. Spatial pattern of dominant plant species was recorded using a distance-based method. Results: Positive understorey-dominant associations were most frequent at both regional and local scale, although negative associations with understorey species were observed for one of the five dominants. At the regional scale, there was a shift in the magnitude of spatial associations, with higher positive associations in the most stressful sites, whereas spatial associations where not affected by the local disturbance gradient. Positive associations were not related to the size of the dominants but rather influenced by the identity of the dominant species. Conclusions: Our study highlights the potential crucial role of facilitation together with the importance of turnover of the dominants in explaining large-scale variation in diversity. However, because positive associations may also be attributed to environmental heterogeneity or co-occurrence of microhabitat preferences of species, experiments are needed to fully assess the relative importance of facilitation versus other drivers of community diversity.
(Journal of Vegetation Science. vol. 20, n° 1100-9233, pp. 916-925, 01/10/2009)
ECODIV, UNIROUEN, NU, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Middle-late Pleistocene deep water circulation in the southwest subtropical Pacific
The modern δ13CDIC distribution in southwest subtropical Pacific deep waters is consistent with a regional mixing regime between water masses of open Pacific Ocean and Tasman Sea origin. This mixing regime is reconstructed across the middle-late Pleistocene using a record of benthic foraminiferal δ13C in a sediment core from the New Caledonia Trough. The relative influence on the mixing regime from open Pacific Ocean deep waters is seen to be significantly reduced during glacial in comparison to interglacial stages over the past 1.1 Ma. The spatial δ13C gradient in the Southern Ocean between deep waters entering the Tasman Sea and the open Pacific Ocean is shown to be consequently greater during glacial than interglacial stages but was generally reduced across the period of the Middle Pleistocene Transition. The existence of strong spatial chemical gradients in the glacial Southern Ocean limits its capacity to act as an enhanced sink for atmospheric carbon.
(Paleoceanography. vol. 24, n° 0883-8305, pp. 4205, 01/10/2009)
PALEOCEAN, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, CLIMAG, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, LOCEAN, IPSL, ENS-PSL, PSL, UVSQ, UPMC, CEA, INSU - CNRS, X, IP Paris, CNES, CNRS, MNHN, IRD, UPMC, INSU - CNRS, CNRS, RSES, ANU, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
GALEACYSTA ETRUSCA COMPLEX: DINOFLAGELLATE CYST MARKER OF PARATETHYAN INFLUXES TO THE MEDITERRANEAN SEA BEFORE AND AFTER THE PEAK OF THE MESSINIAN SALINITY CRISIS
More than one thousand specimens of a morphological complex including Galeacysta etrusca Corradini & Biffi 1988 from 11 Upper Miocene and Lower Pliocene localities of the Paratethyan and Mediterranean realms have been studied using a biometric approach in part relating to the degree of separation between endocyst and ectocyst. Four stable biometric groups have been distinguished statistically, the occurrence or prevalence of which appears closely linked to environmental conditions irrespective of the realm. Group ‘a' is related to brackish conditions, group ‘b' to marine conditions, group ‘c' to freshwater, and group ‘d' to high nutrient levels. Based on an accurate chronology provided by calcareous nannoplankton bioevents and recognition of the Messinian Erosional Surface, this study reveals: 1. the high sensitivity of the Galeacysta etrusca complex for reconstructing paleoenvironments and discriminating phases of connection and isolation of basins; 2. the detailed history of this species complex which originated in the Pannonian Basin at ca. 8 Ma before invading the Dacic Basin during the interval 6–5.60 Ma, then migrating into the Mediterranean during high sea-level connections (the ‘Lago Mare' events just before and after the peak of the Messinian Salinity Crisis, i.e. at 5.60 Ma and during the interval ca. 5.46–5.278 Ma, respectively), and finally into the Black Sea at ca. 5.13 Ma; 3. an improved paleogeography for the Mediterranean and Paratethyan realms with focus on the location of corridors and the timing of when they were active. Based on field observations and dinoflagellate cyst data, we propose that the reflooding of the Mediterranean Basin by Atlantic waters occurred at ca. 5.46 Ma, about 130 kyr before the Zanclean GSSP (5.332 Ma).
(Palynology. vol. 33, n° 0191-6122, pp. 105-134, 11/09/2009)
LDO, INSU - CNRS, UBO EPE, CNRS, PEPS, UCBL, INSU - CNRS, CNRS, IDES, UP11, INSU - CNRS, CNRS, GeoEcoMar, CEREGE, IRD, INRA, AMU, CdF (institution), INSU - CNRS, CNRS
South American Ordovician phyllocarids (Crustacea, Malacostraca)
A detailed morphological analysis of exoskeleton remains of the South American Ordovician phyllocarid crustaceans leads to the recognition of a previously unexpected biodiversity from the Tremadocian up to the Katian. As a result, the genus Caryocaris, as up to now understood, clearly appears to be a comprehensive genus. Taxonomically significant characters are listed and discussed. Two new caryocaridid genera are described: Janviericaris gen. nov., and Ivocaris gen. nov. The diagnosis of the Family Caryocarididae is emended accordingly. In addition to the previous description of Caryocaris acuta Bulman, 1931 from Peru, C. bodenbenderi Aceñolaza & Esteban, 1996 and C. delicata Racheboeuf, Vannier & Ortega, 2000 from Argentina, seven phyllocarid species belonging to five genera are identified from the Tremadocian up to the Sandbian of Argentina and Bolivia. New caryocaridid representatives are Caryocaris acoitensis sp. nov., Ivocaris saltitensis sp. nov., Janviericaris formosa sp. nov. and J. jujuyensis sp. nov.; three other Sandbian and lower Katian forms are provisionally left in open nomenclature as Caryocaris sp. A to C. Ceratiocaridids are represented by the Upper Ordovician genus
(Bulletin of Geosciences. vol. 84, n° 1214-1119, pp. 377 - 408, 11/09/2009)
LDO, INSU - CNRS, UBO EPE, CNRS, UEB, MNHN, UPMC, CNRS, UNLPam
Messinian erosional and salinity crises: View from the Provence Basin (Gulf of Lions, Western Mediterranean)
Though the late Miocene “Messinian Salinity Crisis” has been intensely researched along the circum-Mediterranean basins, few studies have focused on the central part of the Mediterranean Basin and, especially, the pre-salt deposits. To improve our knowledge of the Messinian events, it is imperative to better understand this domain. In this study, we provide a more complete understanding of this central domain in the Provence Basin. We were able to recognize: a) thick marine detrital series (up to 1000 m) derived from the Messinian subaerial erosion which is partly prolongated in the distal part by b) a thick unit of deep marine deposits (up to 800 m) prior to the evaporites; c) a thick presumed alternation of detritals and evaporites (1500 m) below the mobile halite; and d) a two-step transgression at the end of the Messinian. Spatially, we document the eroded shelf to the deep basin (and from the western to the eastern parts of the Gulf of Lions), and temporally, we extend the interpretations from the early deposition of detritic sediments to the final sea-level rise. The results provide a new basis for discussion not only for the development of the Messinian Salinity Crisis but also for the reconstruction of the subsidence history of the Provence Basin.
(Earth and Planetary Science Letters. vol. 286, n° 0012-821X, pp. 139-157, 30/08/2009)
LDO, INSU - CNRS, UBO EPE, CNRS, GM, IFREMER, iSTeP, UPMC, CNRS, PEPS, UCBL, INSU - CNRS, CNRS
Solid-phase extraction and liquid chromatography-tandem mass spectrometry development for the analysis of antibiotics in manure
Pharmaceuticals are now well known micro-pollutants of aquatic systems. They are studied due to sanitary and environmental risks they could represent and especially the antibiotics because of the antibiotic resistance phenomenon. We have focused our research on that group of compounds. Antibiotics mainly enter into the environment either via sewage treatment plant (SWTP) effluent (human origin) or via runoff of land fertilized with sludge from SWTP or manure from livestock (veterinary origin). We have worked on that second origin and studied 2 different types of process before the manure spreading: i) the simple storage of the manure during few months in huge tank ; ii) the treatment process with solid/liquid separation system and 2 different ways of treatment for each phase. Whatever the origin of the contamination, it appears to be a chronic contamination and it is necessary to quantify compounds at trace level (ng/L). For this purpose, we have developed a method for the simultaneous quantification of 23 antibiotics belonging to 9 families. The first step is an extraction of molecules by SPE on Oasis HLB cartridges and the second one is the analysis by Rapid Resolution Liquid Chromatography-tandem mass spectrometry (RRLC/MS/MS) with a 5 cm C18 column and an electrospray ionisation source. The preliminary results show an important contamination of stored pig manure by lincomyin, tetracycline, oxytetracycline and sulfadiazine. The results are discussed according to various ways of manure treatment and uses.
(30/08/2009)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UR GERE, CEMAGREF
Virus-like particles associated with brown muscle disease in Manila clam, Ruditapes philippinarum , in Arcachon Bay (France)
Recently, Manila clam, Ruditapes philippinarum, populations have suffered mortalities in Arcachon Bay (SW France). Mortality was associated with extensive lesions of the posterior adductor muscle, which become progressively brown and calcified. Ultrastructural observations by transmission electron microscopy revealed tissue degradation with necrotized muscle fibres and granulocytomas. Unenveloped virus-like particles (VLPs) were detected in muscle, granulocytic, epithelial and rectal cells. VLPs were abundant in the extracellular space, in the cytoplasm (free or enclosed in vesicles) and in the nucleoplasm of granulocytes. Nuclei and mitochondria of granulocytes displayed changes which suggested reactive oxygen species production and apoptosis induction. VLPs exhibited an icosahedral structure with a diameter of 25 to 35 nm. These observations suggest that the VLPs could belong to the family Picornaviridae or the Parvoviridae.
(Journal of Fish Diseases. vol. 32, n° 0140-7775, pp. 577-584, 01/08/2009)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
PAH biomarker responses in polar cod (Boreogadus saida) exposed to benzo(a)pyrene
With expanding oil and gas activities into the Arctic region, there is a need to evaluate the induction capacity of polycyclic aromatic hydrocarbon (PAH) biomarkers on Arctic marine organisms and to test analytical methods that have been optimized for their temperate counterparts. Polar cod Boreogadus saida were injected intraperitoneally with cod liver oil (solvent control), 6.6+/-3.7, 85+/-48 or 378+/-190 microg kg(-1) wet weight of benzo(a)pyrene (B(a)P), or not injected (control), and liver and bile were sampled at 0 and 16 h and 1, 2, 4 and 7d. The mRNA expression of cytochrome P4501A1 (cyp1a1) and glutathione S-transferase (gst) genes showed a dose-dependent induction in the first 16 h following the injection and a return to basal levels after 4d. The aryl hydrocarbon receptor 2, however, showed no change in mRNA expression. The protein quantification of cytochrome P4501A (CYP1A), through Western blot analysis and the enzyme-linked immunosorbent assay (ELISA), presented similar but weaker and time-delayed responses (4-7d) compared to the gene (16 h to 2d). Ethoxyresorufin O-deethylase (EROD) and glutathione S-transferase (GST) activities increased significantly at day 7 following the gene induction and increase in protein levels. Overall, these biomarkers showed dose-dependent but weak responses to B(a)P and low levels of bile metabolites. The mRNA expressions of oxidative stress genes, superoxide dismutases (sod(Cu/Zn) and sod(Mn)), catalase (cat) and glutathione peroxidase (gpx), were all up-regulated between 16 h and 2d of B(a)P exposure with cat (72-fold) and sod(Cu/Zn) (20-fold) giving the strongest responses in the highest dose. Finally, CAT protein level and enzyme activities showed less clear responses than the genes. The mRNA expression showed the earliest responses, followed by the protein levels. The enzymatic activities were the least sensitive and responded to the exposure after 7d. The study shows the induction capability of biomarkers in polar cod at very low bioavailable doses of B(a)P and provides new information on the selected biomarkers for use in oil monitoring in the Arctic.
(Aquatic Toxicology. vol. 94, n° 0166-445X, pp. 309-319, 01/08/2009)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS