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Dieppois B.,Laboratoire Morphodynamique Continentale et Cotiere | Diedhiou A.,Joseph Fourier University | Durand A.,Laboratoire Morphodynamique Continentale et Cotiere | Fournier M.,Laboratoire Morphodynamique Continentale et Cotiere | And 5 more authors.
Journal of Geophysical Research: Atmospheres | Year: 2013

Sahel rainfall shows pronounced decadal variability and a negative trend between wet conditions in the 1950s-1960s and dry ones in the 1970s-1980s. Using continuous wavelet transform, the quasi-decadal variability (QDV) of rainfall reveals zonal contrasts. The highest QDV is identified in the 1950s-1960s over western Sahel and in the 1970s-1980s over eastern Sahel. The quasi-decadal atmospheric anomalies have been reconstructed using Fourier transform for the 1950s-1960s and the 1970s-1980s, respectively, and assessed by the composite analysis of the QDV phases for the periods before and after 1968. Over western Sahel, the rainfall QDV in the 1950s-1960s is related to the North Atlantic sea surface temperature (SST) variability, as highlighted by the wavelet coherence. A southward shift trend of the Intertropical Convergence Zone (ITCZ) is identified through an enhancement of northeasterly fluxes and moisture convergence over the western part of West Africa. A decrease (increase) of southern (northern) subtropical sinking motions seems to be involved. In the 1970s-1980s, a strengthening of cross-equatorial Atlantic SST and pressure gradients is related to an increase of monsoon flow from lower troposphere up to the midtroposphere and to the northward shift of the ITCZ, mainly over eastern Sahel. The Pacific SST influence is also identified, which involves changes in the global zonal circulation. Key Points Zonal contrasts are detected in Sahel rainfall at quasi-decadal scale Quasi-decadal signals of the WAM are identified in both wet and dry periods Modifications of SST forcing are observed between wet and dry periods ©2013. American Geophysical Union. All Rights Reserved.


Dauvin J.C.,Normandie University | Dauvin J.C.,Laboratoire Morphodynamique Continentale et Cotiere | Dauvin J.C.,French National Center for Scientific Research | Andrade H.,Akvaplan Niva | And 3 more authors.
Ecological Indicators | Year: 2016

Among the macro-invertebrates used for the assessment of soft-bottom communities, most polychaetes are classified as tolerant/opportunistic to pollution while amphipods are considered as sensitive. These taxa have been used in several ecological indices, such as the simple abundance ratio between Polychaeta and Amphipoda or the Benthic Opportunist Annelids Amphipods (BO2A) index, to assess the Ecological Quality Status -EcoQs- of soft-bottom communities. In terms of Taxonomic Sufficiency (TS), the polychaete/amphipod ratio (i.e. at the level of the class/order) has been proved to be effective in identifying major changes in benthic communities following disturbances. However, an underlying issue is to assess the acceptable TS limit value needed to state accurately the quality of the benthic environment. We tested three indices using 18 series of observations carried out in five north-eastern Atlantic and Mediterranean zones impacted by oil spills, oil and gas production, brine and urban sewage, harbours and aquaculture farms within impacted and control areas. Similar results to BO2A were obtained when limiting the TS at the level of Polychaete opportunistic families, which required a lower degree of taxonomic expertise, and classifying all amphipods as sensitive taxa. In such a way that the EcoQs given by the BPOFA (Benthic Polychaete Opportunistic Families Amphipods) was very similar to those given by the BO2A (Benthic Opportunistic Annelids Amphipods). © 2015 Elsevier Ltd. All rights reserved.


Bakalem A.,Montpellier SupAgro | Dauvin J.-C.,Normandie University | Dauvin J.-C.,Laboratoire Morphodynamique Continentale et Cotiere | Dauvin J.-C.,French National Center for Scientific Research | Grimes S.,National School of Marine Science and Coastal Planning
Journal of the Marine Biological Association of the United Kingdom | Year: 2014

Recent sampling surveys (2011-2012) of the shallow (0-50 m) hard-bottom communities and re-examination of some soft-bottom communities (5-143 m) along the Algerian coast have allowed the collection of 33 species (five Caprelloidea, 27 Gammaridea and one Hyperiidea), which were not recorded before in the inventory of the marine amphipod fauna of Algeria (Bakalem & Dauvin, 1995; Grimes et al., 2009). This paper reports the number of specimens sampled for each of these 33 species and provides data on their geographical distribution and habitats. Fourteen of the species (43%) are considered to be endemic to the Mediterranean Sea; 15 others are north-eastern Atlantic and Mediterranean species, and the four last are cosmopolitan species. Twenty-nine of the new records are known for Italian waters and 19 in Greek waters where there is intensive amphipod inventory. The total number of marine amphipod fauna in Algeria is now 332. Copyright © Marine Biological Association of the United Kingdom 2014.


Dauvin J.-C.,Normandie University | Dauvin J.-C.,Laboratoire Morphodynamique Continentale et Cotiere | Dauvin J.-C.,French National Center for Scientific Research | Dauvin J.-C.,Station Marine Of Luniversite Of Caen Basse Normandie | And 14 more authors.
Cahiers de Biologie Marine | Year: 2014

On the western coast of the Cotentin peninsula (English Channel, France), small estuaries, called havres, were transitional systems between terrestrial and aquatic habitats. This study concerns the macrobenthos and the evolution of the habitat areas of two estuaries: Blainville and Regnéville. In 2002, 2007 and 2010, aerial photographs showed that the total areas for both estuaries were stable for the last 10 years. Macrofauna characteristics (e.g., species richness, abundance, and biomass) and habitat areas were used to estimate the carrying capacity of both Blainville and Regnéville estuaries in 2010 as an indicator of their trophic value. The estimated carrying capacities showed the importance of salt marshes in both estuaries. However, the carrying capacity was higher in Regnéville (0.408 tAFDW.ha-1) than in Blainville (0.147 tAFDW.ha-1), which was due to the high degree of anthropogenic changes in the Blainville estuary. Salt marsh data revealed the dominance of typical north-eastern Atlantic estuarine species, (i.e., Carcinus maenas, Orchestia gammarellus and Talitrus saltator), with 135 to 1,000 ind.m-2 and a biomass between 23 to 80 g AFDW.m-2 The abundances and biomasses per m2 of the macrofauna observed in those small estuaries were similar to those observed in other larger north-western Atlantic estuaries and provide similar services such as feeding zones for fishes and birds. In the future, the Regnéville habitat areas must be preserved to maintain high benthic biomasses.


Kaim-Malka R.A.,Aix - Marseille University | Bellan-Santini D.,Aix - Marseille University | Dauvin J-C.,Normandie University | Dauvin J-C.,Laboratoire Morphodynamique Continentale et Cotiere | Dauvin J-C.,French National Center for Scientific Research
Zootaxa | Year: 2016

Four Haploops species collected in the North Atlantic Ocean are studied. One of them, H. islandica is a new species for the science. The three other species, H. carinata, H. setosa, H. robusta, were described from a long time, but many con-fusions exist about these species because their morphological nearness. The four species are described and illustrated in detail, and their distribution around the Iceland is specified. A key of the 23 species known nowadays is given permetting to separate the different species of the Haploops genus. Copyright © 2016 Magnolia Press.


Gothland M.,University of Lille Nord de France | Gothland M.,University Of Lille1 | Gothland M.,CNRS Laboratory of Oceanology and Geosciences | Dauvin J.C.,Normandie University | And 24 more authors.
Estuarine, Coastal and Shelf Science | Year: 2014

Comprehending marine invasions requires a better knowledge of the biological traits of invasive species, and the future spread of invasive species may be predicted through comprehensive overviews of their distribution. This study thus presents the current distribution of a non-indigenous species, the Asian shore crab Hemigrapsus takanoi, as well as the species population characteristics (size distribution and cohorts), based on a five-year survey (2008-2012) along the French coast of the English Channel. Two large populations were found near harbours: one on the Opal Coast (where density reached 61±22ind.m-2, mean±s.d., in Dunkirk harbour) and one on the Calvados coast (density up to 26±6ind.m-2, mean±s.d, in Honfleur harbour). H.takanoi exhibited a short life cycle, a rapid growth, an early sexual maturity and a high adult mortality. These features, combined with previously described high fecundity and high dispersal ability, endow this species with an 'r-selected strategy'. This strategy, which usually characterises species with a high colonisation ability, would explain the success of H.takanoi for colonising the French coast of the Channel. However, the species was found only in harbours and their vicinity; H.takanoi thus exhibited a discontinuous distribution along the 700km of coastline. These results are discussed regarding sediment preference and potential introduction vectors. Hemigrapsus takanoi is now considered as established on the French coast and further studies are needed to evaluate the consequences of its introduction on the structure and functioning of the impacted shores. © 2014 Elsevier Ltd.


Navon M.,Normandie University | Navon M.,Laboratoire Morphodynamique Continentale et Cotiere | Navon M.,French National Center for Scientific Research | Navon M.,Station Marine Of Luniversite Of Caen Basse Normandie | And 4 more authors.
Cahiers de Biologie Marine | Year: 2013

Recreational clam digging is a traditional activity on the large intertidal zone of the western coasts of the Cotentin (western English Channel). A variety of fishing gears are used to harvest the target species the warty venus Venus verrucosa (Linnaeus, 1758). In this note, the immediate effect (i.e., four days) of fork harvesting was studied during the March 2012 spring tide, following a control-impact design with a control station and three impacted stations using pebble forks. An immediate significant decreases of coarse sand and gravel benthic macrofauna is observed in fishing area. In the future, it is recommended that pebble fork fishing should be prohibited to harvest this target species.


Garcia-Hermosa I.,University of Le Havre | Brossard J.,University of Le Havre | Cohen Z.,University of Le Havre | Perret G.,University of Le Havre | And 12 more authors.
Renewable Energies Offshore - 1st International Conference on Renewable Energies Offshore, RENEW 2014 | Year: 2015

As part of OFELIA experiments were carried out to characterize the flow field around a cylinder for regular and irregular wave conditions including a 1:10 storm. Data collation included free surface and flow velocity with Acoustic Doppler Velocimeter (ADV) and Particle Image Velocimetry (PIV). Preliminary results identified flow patterns up- and downstream of the cylinder that could play a role on the sediment erosion and deposition patterns near the foundation area, in the short and long term scales. © 2015 Taylor & Francis Group, London.

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