Chapitre 9. Géomorphologie, faune et paléoenvironnement
(21/02/2026)
LOB, INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, Inrap, CEREGE, IRD, INRA, AMU, CdF (institution), INSU - CNRS, CNRS, IMEP, AU, CNRS, Inrap, Marseille, Inrap
Constitution de “ MARINPERTUIS ” une base de données sur la biodiversité de la macrofaune marine dans les Pertuis charentais : analyse historique
Une revue quasi exhaustive des travaux publiés depuis le début du 18'm, siècle a été réalisée. Les résultats ont été réunis dans une base de données intitulée MARIN PERTUIS (Marine Invertebmaes of the Pertuis Charentais Sea). Sont recensées à ce jour 858 espèces mais ce chiffre est vraisemblablement sous-estimé. Une première exploitation de la base de données permet de retracer, par période décennale, l'évolution depuis 3 siècles de la notion de diversité marine dans les Pertuis Charentais.
(Journal de la Recherche Océanographique. vol. 26, pp. 129-131, 21/02/2026)
LIENSs, INSU - CNRS, ULR, CNRS, CREMA, IFREMER, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, L3I, ULR
Swash platform morphology in the ebb-tidal delta of the Barra Nova inlet, South Portugal
An artificially created inlet cut in the barrier island system of the Ria Formosa (South Portugal) was studied by performing fieldwork from January to March 1999. This study focuses on the updrift swash platform associated with the ebb-tidal delta. The area was monitored during a month with fair weather conditions studying morphodynamics, sedimentary dynamics and hydrodynamic measurements. The results were used to establish a sedimentary budget of the swash platform and to quantify the morphodynamics. A strong accretion was observed on the swash platform, which corresponds to the volume of sediment provided by the longshore drift on the adjacent updrift coast. A redistribution of sediment was observed on the platform, changing the orientation of the main swash platform axis. The swash bars forming this area are very dynamic (20m migration in 8 days), and the entire swash platform is migrating toward the inlet resulting in progressive closure of the system. Characteristics of the inlet and morphodynamics of the swash platform were used to validate a conceptual model of by-passing by ebb-tidal delta breaching for this system.
(Journal of Coastal Research. vol. 17, n° 0749-0208, pp. 784-791, 21/02/2026)
BRGM, BIAF, UA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
A new shipborne microwave refractometer for estimating the evaporation flux at the sea surface
After a brief description of humidity measurement and a short presentation of methods of microwave refractometry for evaporation flux, a new X-band refractometer system is presented. Based on a new design and a new material for the microwave cavity, it does not need calibration for refractive index variations because of its reduced thermal time constant. The new device has been combined with a sonic anemometer and traditional mean meteorological measurements on a 12-m shipborne mast. It has been found to be very efficient for obtaining humidity fluctuations and fluxes in the CATCH 97 (Couplage avec l'ATmosphère en Conditions Hivernales) and FETCH 98 (Flux, Etat de la mer et Télédétection en condition de fetCH variable) experiments under various wind and stability conditions. The inertial subrange is of very high quality. To first order, the evaporation flux and refractive index flux are very similar. In extreme meteorological conditions, such as those encountered during CATCH, the sensible heat flux contribution must be determined independently. A great advantage of the system is that the contamination by salt, as is typical for other devices at sea, has been found to be negligible for the conditions encountered.
(Journal of Atmospheric and Oceanic Technology. vol. 18, n° 3, n° 0739-0572, pp. p. 459-475, 21/02/2026)
CETP, UVSQ, INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IRPHE, AMU, ECM, CNRS, CNRM, INSU - CNRS, CNRS, Comue de Toulouse
Artificial cold-adapted microbial mats cultured from Antarctic lake samples. 1. Formation and structure
(Aquatic Microbial Ecology. vol. 26, n° 0948-3055, pp. 115-125, 21/02/2026)
LEFE, INEE-CNRS, CNRS, UT3, Comue de Toulouse, CNRS, Toulouse INP, Comue de Toulouse, ECOLAG, UM2, IFREMER, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Recent Holocene paleo-environmental evolution and coastline changes of Kition, Larnaca, Cyprus, Mediterranean Sea
Sedimentological, paleontological analysis and 14C dating of 17 cores obtained in the vicinity of the Phoenician military harbor (VIII–IV BC) of Kition Bamboula (Cyprus) provide new paleo-environmental information for the reconstruction of shoreline changes for Kition and Larnaca Bay over the last 4000 years. We propose that a communication existed between the inner harbor of Bamboula (presently 400 m inland) and the northern district of Lichines, which was a marine embayment. Our core data led us to revisit the previous hypothesis of a direct east–west channel between the harbor and the open sea (Nicolaou, K., 1976. The historical topography of Kition. Studies in Mediterranean Archaeology, Göteborg, vol. 153, pp. 1–373; Gifford, J.A., 1978. Paleogeography of archaelogical sites of the Larnaca lowlands, southeastern Cyprus. PhD Thesis, University of Minnesota, pp. 1–192). We propose instead that a spit of coarse material isolated the lagoon from the open sea from 2600 to 1600 years BP.
(Marine Geology. vol. 170, n° 0025-3227, pp. 205-230, 01/10/2000)
CEREGE, IRD, INRA, AMU, CdF (institution), INSU - CNRS, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, URA 1761 / ESA 7073 / FRE 2400, MNHN, UPMC, CNRS, MOM, UL2, CNRS
Short- and long-term sedimentation on Montportail–Brouage intertidal mudflat, Marennes–Oléron Bay (France)
The intertidal mudflat of Montportail-Brouage is 4 km wide and extends over about 30% of intertidal area of the Bay of Marennes-Oléron. The sampling area was a cross-shore transect (east–west) in the mid-part of the mudflat, so as to overlap the different geomorphological features, from the shore to the central channel. Particularly distinctive were zones of shore-oblique ridges and runnels, and small channels. The short-term erosion-sedimentation processes related to these bedforms, and their effects on the long-term stability of these structures are poorly known. Thus, sediment budget is difficult to assess in the long term, due to temporal variations. Monthly sedimentological surveys were performed from March 1997 to May 1998. Six stations were sampled by coring for determination of water content, dry density, grain size and carbonate content of the sandy fraction, measured on the topmost 5 cm. Within the ridge and runnel zone, this sampling was done on both structures along with the determination of depth profiles of macrofauna species. Radiographic profiles to a depth of 50 cm were made at each of the 6 stations for description of the sedimentary facies, and radioisotope profiles () were made at four stations. Wet bulk density appeared to be roughly constant (1.39–1.44 kg m−3) over the whole mudflat below 2 or 3 cm. For the levels 0–1 and 1–2 cm, the bulk density showed much more variation, in particular in the runnels. These variations were due to episodic deposits of fluid mud (wet bulk density <1.25 kg m−3). The sand content decreased from the lower part of the mudflat to the upper part, particularly in the fluid mud. On the contrary, the carbonate content of the sand fraction increased in the upper part by accumulation of foraminifera associated with shell lag deposits. 7 Be measurements revealed a short-term sedimentation of fluid mud (up to 21.04 cm yr−1), particularly in runnels from the upper mudflat, thus indicating a temporary deposit, easily resuspended by wave action. 210 Pbexc measurements showed a long-term sedimentation rate which was 4 times higher in the lower part (0.97 cm yr−1) of the mudflat (near oyster reefs and mussel “bouchots”) than in the upper part (0.26 cm yr−1). In the middle mudflat, ridges and runnels exhibited a large difference of the long-term sedimentation rates, 0.70 cm yr−1 on ridges and only 0.07 cm yr−1 in runnels, that could be considered as a passageway for fluid mud transport. In the middle mudflat, where ridges and runnels occurred, synopsis of observations indicated that a 30 yr old and 18 cm thick ridge layed on a more than 100 yr old basement mudflat. This bedform is maintained through short- and long-term sedimentations. In the runnels, always flooded by water even at low tide, the short-term sedimentation was 21.04 cm yr−1, but these sediments can be easily resuspended by tidal currents, inducing a weak long-term sedimentation (0.07 cm yr−1). In the ridges, the short-term sedimentation was 7.27 cm yr−1; however, due to potential impacts of drying processes, along biostabilization by epipelic diatoms during subaerial exposure at low tide, the short-term sedimentation contributed to a long-term sedimentation of 0.70 cm yr−1.
(Continental Shelf Research. vol. 20, n° 0278-4343, pp. 1513 - 1530, 10/09/2000)
CREMA, IFREMER, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LIENSs, INSU - CNRS, ULR, CNRS
Physiography and recent sediment distribution of the Celtic Deep-Sea Fan, Bay of Biscay
(Marine Geology. vol. 169, n° 0025-3227, pp. 207-237, 01/09/2000)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, IFREMER, SHOM, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA, PALEOCEAN, LSCE, UVSQ, INSU - CNRS, CNRS, DRF (CEA), CEA
A census of macroparasites in an intertidal bivalve community, Arcachon Bay, France.
Amongst the potential biotic factors affecting bivalve population dynamics, parasitism has received little attention. Examination of the three dominant bivalves (the edible cockle Cerastoderma edule, the blue mussel Mytilus edulis, and the Manila clam Tapes philippinarum) on an intertidal sandflat in the Bay of Arcachon (French Atlantic coast) revealed the occurrence of a rich community of macroparasites. These parasites belong to digenean trematodes (ten species), turbellarians (one species), cestodes (one species) and copepods (one species). The mean number of parasite species increased with shell length and reached 4 in cockles (maximum = 7 per ind.), 2.6 in mussels (max. = 5 per ind.) and only 1.7 in clams (max. = 4 per ind.). Total parasite prevalence was higher in cockles and mussels (84.9 and 72.3 %, respectively) than in clams (49.7 %). Host specificity was much higher for non-encysted larvae than for encysted metacercariae or non digenes. The occurrence of sporocysts of the digene Labratrema minimus in cockles seems to induce a lower infection by other parasite. The youngest bivalves (less than 10 mm in shell size) were nearly free of parasites. From the ‘shell size/parasite intensity’ relationship, the macroparasites are highly suspected to increase the mortality of recruits and adult bivalves. © 2000 Ifremer/CNRS/IRD/Éditions scientifiques et médicales Elsevier SAS
(Oceanologica Acta, n° 0399-1784, 01/08/2000)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Modeling δ15N evolution: First palaeoceanographic applications in a coastal upwelling system
The delta(15)N Signal in marine sediments appears to be a good palaeoceanographic tracer. It records biological processes in the water column and is transferred to and preserved in the sediments. Changes in forcing factors in upwelling systems may be recorded by delta(15)N. These forcing conditions can be of a biogeochemical nature, such as the initial isotopic signal of the nutrients or the trophic structure, or of a physical nature, such as wind stress, insolation, temperature or dynamic recycling. A simple nitrogen-based trophic chain model was used to follow the development of the nitrogen isotopic signal in nutrients, phytoplankton, zooplankton and detritus. Detrital delta(15)N, influenced by the isotopic signature of the upwelled nutrients and isotopic fractionation along the trophic chain (photosynthesis and zooplankton excretion), was then compared to the sedimentary signal measured off Mauritania. In our model, the biological variables are transported at shallow depths by a simple circulation scheme perpendicular to the coast depicting a continental shelf recirculation cell. Because cell length depends on the extension of the continental shelf, modifications of the cell length mimic sea level changes. Long cell length (high sea lever) scenarios produce higher delta(15)N values whereas short cell length scenarios result in lower values as in the glacial low sea level periods. Despite changes in many climatic parameters throughout this period, our results show that changing the sea level is sufficient to reconstruct the main pattern of the sedimentary delta(15)N variations offshore of the Mauritanian upwelling, i.e. an increase from about 3 parts per thousand to 7 parts per thousand during the deglaciation, without invoking any change in nitrogen fixation or denitrification.
(Journal of marine research. vol. 58, n° 0022-2402, pp. 609-630, 01/07/2000)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LEGOS, IRD, UT3, Comue de Toulouse, INSU - CNRS, CNES, CNRS