Temporal variability of carbon recycling in coastal sediments influenced by rivers: assessing the impact of flood inputs in the Rhône River prodelta
River deltas are particularly important in the marine carbon cycle as they represent the transition between terrestrial and marine carbon: linked to major burial zones, they are reprocessing zones where large carbon fluxes can be min-eralized. In order to estimate this mineralization, sediment oxygen uptake rates were measured in continental shelf sediments and river prodelta over different seasons near the outlet of the Rhône River in the Mediterranean Sea. On a selected set of 10 stations in the river prodelta and nearby continental shelf, in situ diffusive oxygen uptake (DOU) and laboratory total oxygen uptake (TOU) measurements were performed in early spring and summer 2007 and late spring and winter 2008. In and ex situ DOU did not show any significant differences except for shallowest organic rich stations. Sediment DOU rates show highest values concentrated close to the river mouth (approx. 20 mmol O 2 m −2 d −1) and decrease offshore to values around 4.5 mmol O 2 m −2 d −1 with lowest gradients in a south west direction linked to the preferential transport of the finest riverine material. Core incubation TOU showed the same spatial pattern with an averaged TOU/DOU ratio of 1.2±0.4. Temporal variations of sediment DOU over different sampling periods, spring summer and late fall, were limited and benthic mineralization rates presented a stable spatial pattern. A flood of the Rhône River occurred in June 2008 and delivered up to 30 cm of new soft muddy deposit. Immediately after this flood, sediment DOU rates close to the river mouth dropped from around 15-20 mmol O 2 m −2 d −1 to values close to 10 mmol O 2 m −2 d −1 , in response to the deposi-tion near the river outlet of low reactivity organic matter associated to fine material. Six months later, the oxygen distribution had relaxed back to its initial stage: the initial spatial distribution was found again underlining the active microbial degradation rates involved and the role of further deposits. These results highlight the immediate response of the sediment oxygen system to flood deposit and the rapid relaxation of this system towards its initial state (6 months or less) potentially linked to further deposits of reactive material.
(Biogeosciences. vol. 7, n° 1726-4170, pp. 1187-1205, 11/04/2026)
LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, OCEANIS, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, LEP, EEP, IFREMER, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IPGP - UMR_7154, INSU - CNRS, IGN, UR, IPG Paris, CNRS, UPCité, CEFREM, UPVD, INSU - CNRS, CNRS, LECOB, SU, CNRS, OOB, SU, CNRS
Formation of Thetis Deep metal-rich sediments in the absence of brines, Red Sea
Almost all Red Sea deeps contain metal-rich sediments covered by brine pools. It is generally agreed that these metal-rich deposits precipitated from overlying metal-rich brines that originated from migrating hydrothermal fluids. No brine pool has ever been reported in Thetis Deep, inciting us to evaluate if such a brine layer ever occurred in the deep during the past. In order to address that questioning, a study combining mineralogical, geochemical (major-, minor-, rare-earth elements) and isotopic (Sr. Nd. Pb) approaches was completed on cored sediments and extracted interstitial waters from inside and outside the deep.;The sediments have an overall hydrothermal origin, as shown by the REE concentrations and patterns, metal contents, and Pb-Nd isotopic data, all pointing to a mantle signature. The intensity of the hydrothermal activity varied with time in the deep; the most intense episode resulting in an almost pure Fe-oxi-hydroxide layer. Varied chemical arguments, especially the Zr and REE data of the sediments, favor the fact that the whole sedimentation in Thetis Deep occurred in the absence of a stable, salt-rich and mineralized brine pool, and that no brine layer ever existed. This conclusion is supported by the constant Sr isotope composition of the sediment and its interstitial waters that are almost identical to that of the Red Sea seawater. The study also suggests that hydrothermal activity monitored fluid supplies that interacted differently with seawater in the different Red Sea deeps, resulting in an overall formation of metal-rich sediments, but along varied local conditions. (C) 2009 Elsevier B.V. All rights reserved.
(Journal of Geochemical Exploration. vol. 104, n° 0375-6742, pp. 12-26, 11/04/2026)
LHyGeS, ENGEES, UNISTRA, INSU - CNRS, CNRS, UAG, INSU - CNRS, UM, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Relationships between sinking particulate matter, early diagenesis, and sedimentary recording in the Bay of Biscay margin)
(11/04/2026)
LPGN, UN, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Deglacial environments in eastern Prydz Bay, East Antarctica
A high-resolution continuous record of diatom census counts and diatom specific biomarkers in sediment core NBP0101-JPC24 allows assessment of oceanographic and environmental conditions in eastern Prydz Bay during the deglaciation (11 100e9000 cal yr BP) at decadal timescale. Our study improves previous snapshots investigations based on resin-embedded thin sections and presents a new proxy that compliments the diatom census counts. Our results suggest that the ice sheet retreat over the core site is dated ate11 100 cal yr BP, setting the onset of local deglaciation and subsequent open marine conditions. The glacial retreat in Prydz Bay is due to global warming initiated at 18 cal ka BP and the regional development of the Prydz Bay cyclonic gyre. Our results further demonstrate that the deglaciation in eastern Prydz Bay can be separated in four phases: the first between 11 100 and 10 900 cal yr BP when the ice shelf was proximal and sea ice was almost perennial; the second and the third phases between 10 900e10 400 cal yr BP and 10 400e9900 cal yr BP, respectively, when the ice shelf retreated and seasonal sea ice cycle consequently developed promoting warmer water to pump into the bay within the gyre, which in turn forced the ice shelf recession and the yearly sea ice cycle establishment; and the fourth between 9900 and 9000 cal yr BP when Holocene condition were set with a recurrent seasonal sea ice cycle and a well established Prydz Bay gyre.
(Quaternary Science Reviews. vol. 29, n° 0277-3791, pp. 2731-2740, 11/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LOCEAN, IPSL, ENS-PSL, PSL, UVSQ, UPMC, CEA, INSU - CNRS, X, IP Paris, CNES, CNRS, MNHN, IRD, UPMC, INSU - CNRS, CNRS
Sedimentary archives of the French Atlantic coast (inner bay of Vilaine, south Brittany) : depositional history and late Holocene climatic signals.
(Continental Shelf Research. vol. 30 (10–11), n° 0278-4343, pp. 1250–1266, 11/04/2026)
PEPS, UCBL, INSU - CNRS, CNRS, M2C, UNICAEN, NU, INSU - CNRS, UNIROUEN, NU, CNRS, CEREGE, IRD, INRA, AMU, CdF (institution), INSU - CNRS, CNRS, LETG, UNICAEN, NU, UA, EPHE, PSL, UBO EPE, UR2, CNRS, IGARUN, UN, LDO, INSU - CNRS, UBO EPE, CNRS, GEOARCHI, UBS, UBO EPE, IBSHS, UBO EPE
Recent expansion of the oriental shrimp Palaemon macrodactylus (Crustacea: Decapoda) on the western coasts of France
The invasive oriental shrimp Palaemon macrodactylus Rathbun, 1902 has considerably extended its distribution in transitional waters along the Atlantic and Channel coasts of France during the period 2007-2010. The most probable method of a primary introduction of this species is ballast waters, but passive transport by water currents is also a possible mechanism of colonization (secondary introductions). Palaemon macrodactylus is a powerful invader of transitional waters and these new populations should be monitored in the future to assess any consequences to native species.
(Aquatic Invasions. vol. 5, n° 1798-6540, pp. S103-S108, 11/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UR EPBX, IRSTEA, IRSTEA, LIENSs, INSU - CNRS, ULR, CNRS, IFREMER
Estimating turbidity and total suspended matter in the Adour River plume (South Bay of Biscay) using MODIS 250-m imagery
The Basque coastal waters (South Bay of Biscay) are directly influenced by the Adour River freshwater plume. The Adour outflow leads to important variations of suspended matter concentrations and turbidity, which in turn may affect biological productivity and water quality. This study aims at both developing specific algorithms and testing the efficiency of atmospherically corrected MODIS-Aqua 250-m surface reflectance product (MYD09) to map total suspended matter concentrations and turbidity within the Adour coastal region. First, regional empirical algorithms based on in-situ data were tested to retrieve the concentration of total suspended matter and turbidity from the remote sensing reflectance. Then, the respective sensitivity of MODIS surface reflectance bands 1 and 2 for water quality application was investigated as well as the quality of atmospheric corrections. Finally, selected algorithms were applied to the MYD09 product. The resulting 250-m resolution maps were then compared to 1000-m maps produced by IFREMER and comparisons between satellite measurements and in-situ sampling points were performed. Results show that MODIS-Aqua band 1 (620-670 nm) is appropriate for predicting turbidity and total suspended matter concentrations using polynomial regression models, whilst band 2 is unadapted. Comparison between total suspended matter concentration 250-m resolution maps and mineral suspended matter 1000-m maps (generated by IFREMER) produced consistent results. A high correlation was obtained between turbidity measured in-situ and turbidity retrieved from MODIS-Aqua satellite data. (C) 2009 Elsevier Ltd. All rights reserved.
(CONTINENTAL SHELF RESEARCH. vol. 30, pp. 379-392, 11/04/2026)
IFREMER, DYNECO, IFREMER, LOV, INSU - CNRS, SU, CNRS, IMEV, INSU - CNRS, SU, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Prevalence, intensity, and aneuploidy patterns of disseminated neoplasia in cockles (Cerastoderma edule) from Arcachon Bay: Seasonal variation and position in sediment
The present report presents the first evidence of disseminated neoplasia (DN) in cockles Cerastoderma edule from Arcachon Bay (France). Aneuploidy of neoplastic cells allowed the use of flow cytometry (FCM) to diagnose and stage DN. A 1 year survey (2007) of the prevalence and intensity (% of aneuploid circulating cells in neoplastic cockles) was conducted. Prevalences ranged from 2.2% (June) to 13.6% (May), and disease intensity ranged from 18.7% (June) to 95.5% (September). These percentages were not correlated with seawater temperature, but rather showed unexplained oscillations over the year. Prevalence and intensity of DN were higher in cockles found at the surface of sediment compared to those buried normally (11.8% vs. 6.7% and 53.0% vs. 40.6%, respectively, p < 0.05). DN could thus be one mechanism leading to unexplained presence of cockles at the surface of the sediment in Arcachon Bay. Ploidy characteristics of neoplastic cells were also investigated using FCM, revealing an unusual, broad continuum of ploidy distribution from 1.6 to 9.6n. Ploidy values were not in whole numbers in contrast to the rounded values reported in other studies. Ploidy varied according to DN intensity, with the ploidy distribution of neoplastic cells from lightly-diseased cockles being unimodal (3.7n median). In contrast, highly-diseased cockles showed a bimodal ploidy distribution (3.0n and 4.7n medians). This suggests that, in cockles from Arcachon Bay, mechanisms leading to aneuploidy are complex, developing during disease progression.
(Journal of Invertebrate Pathology. vol. 104, n° 0022-2011, pp. 110-118, 11/04/2026)
CEMCA, UBO EPE, INC-CNRS, CNRS, IBSAM, UBO EPE, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LEMAR, IRD, IFREMER, UBO EPE, CNRS
Interactive effects of metal contamination and pathogenic organisms on the marine bivalve Cerastoderma edule
The present study evaluated the interactive effects of cadmium contamination and pathogenic organisms (trematodes Himasthla elongata and bacteria Vibrio tapetis) singularly and in combination during 7 days on the bivalve Cerastoderma edule. Some defense-related activities were analyzed such as genetic expression, metallothionein and immune responses. Trematode metacercarial infection, similar whatever the treatment, induced the strongest responses of immune parameters. Particularly, the interaction between cadmium and parasite exposures induced unusual responses on gene expression and immune responses. No effect of bacterial challenge appeared on bivalve responses, nevertheless a strong mortality of V. tapetis infected cockles occured between 7 and 14 days. Cadmium bioaccumulation was significantly modulated by both pathogenic organisms. Furthermore, an antagonistic effect of trematodes and bacteria was shown on metal bioaccumulation of co-infected cockles. These results highlighted the importance of considering the multiplicity of perturbation sources in coastal ecosystems to assess the health status of organisms.
(Marine Pollution Bulletin. vol. 60, n° 0025-326X, pp. 515-525, 11/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LEMAR, IRD, IFREMER, UBO EPE, CNRS
Bivalve population health: Multistress to identify hot spots
This study investigated some stress (metals, parasites) and response (immunity, metallothionein) factors in two cockle and two Manila clam populations. Data from eight seasons were averaged to obtain global baseline values. Stress/response characteristics of each population were compared to population health status that was determined through population dynamics parameters. Four different scenarios were discussed: (1) a lightly stressed cockle population with correct population health but with a risk of deterioration (hot spot); (2) a lightly stressed introduced cockle population threatened of extinction. In this case ecological factors were suspected; (3) a moderately stressed clam population with moderate adaptative response. The population was sustainable but the level of stress should not increase (hotspot); and (4) a stressed clam population and unfavourable ecological conditions preventing clam settlement. This monitoring highlighted that the discrepancy between population health and stress levels could be due to insufficient response by bivalves and/or by unfavourable ecological factors.
(Marine Pollution Bulletin. vol. 60, n° 0025-326X, pp. 1307-1318, 11/04/2026)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LEMAR, IRD, IFREMER, UBO EPE, CNRS