Publications 2006

 2006  - Consommation de la macrofaune invertébrée benthique par les oiseaux d’eau en baie du Mont-Saint-Michel 

Auteurs : Le Mao P., Pasco P.Y. et Provost S.

Alauda, 2006, vol. 74, no1, pp. 23-36 [14 page(s)]  

An evaluation of the energy transfer between zoobenthos and water birds in the Mont-Saint-Michel bay was carried out from October 2003 until September 2004. Global consumption by waders is similar to that estimated on data collected 20 years ago, in spite of strong variations in seasonal occurrence and species composition of shorebirds populations in the bay. Total consumption (including gulls and predatory anseriformes) is about 2,15 g ash free dry weight/m2 /year, a very low figured if compared to results from the Wadden Sea. These two results seems to confirm the initial findings from the PNEC research program in the Mont-Saint-Michel bay: the bay is an oligotrophic system (oceanic type) presenting a strong functional inertness in the mid and long term, because little subjected to the effects contributing coastal rivers. The situation is very different in many other coastal areas, especially in the Wadden Sea which is an eutrophic system, with strong between year variations, where the, often very high primary and secondary production, are reinforced by nutrients flows induced by eutrophic freshwaters streams.

Keywords : Vertebrata ; Aquatic environment ; Europe ; Bay of Saint-Michel ; Aves ; Marine environment ; France ; Macrofauna ; Benthic zone ; Waterfowl ; Fauna

 2006  - The benthic resting cyst: a key actor in harmful dinoflagellate blooms  

Auteurs : Genovesi-Giunti B., Laabir M., Vaquer A.

A review. Life and Environment 56 (4) : 327-337

Resting cysts (RC) constitute a coupling between benthic and pelagic stages and influence the bloom development in a number of bloom forming dinoflagellate species. Encystment capability coupled with high vegetative cell density (> one million cells l- 1) contribute to the formation of an accumulation zone: “the cyst bank”, which is directly linked to the success of bloom initiation and its recurrence. The survival time of benthic RCs (few weeks to several years), their viability which could be negatively affected by predation, and their mandatory dormancy period (few days to several months) are variable and influence the seeding potential of the population significantly. Excystment rate, mainly controlled by temperature and oxygen level, and the germling cells’ viability determine the inoculum size. Many biological processes in RCs have been shown to be controlled by endogenous and environmental factors, and vary between species and within the same species as a function of geographic strains.

 2006  - The bottom cell clusters: a new hypothesis for bloom initiation of cysts forming dinoflagellates 

Auteurs : Genovesi-Giunti B., Vaquer A., Laabir M., Vincent C., Fiandrino A, Collos Y., Pastoureaud A.

Proceeding of the 12th international conference on Harmful algae, Copenhague, Danemark. (sous presse).

 2006 - Spatial management of near shore coastal areas: the use of Marine Protected Areas (MPAs) in a fisheries management context  

Auteurs : Claudet, J., Roussel S., Pelletier D., Rey-Valette H.

Vie et Milieu – Life and Environment 56, 301-305

 2006 - Indicators to assess the effectiveness of marine protected areas on rocky reef fish assemblages: an application to a Mediterranean marine reserve 

Auteurs : Claudet J., Pelletier D., Jouvenel J.-Y., Bachet F., & Galzin R.

Biological Conservation 130, 349-369

 2006 - Environmental stress of the pacific oyster Crassostrea gigas during summer period 

Auteurs : Burgeot T., Quirion S., Quiniou F., Knoery J. Gagné F., Gagnaire B., Renault C., Haure J., Moraga D.

Supplement to Marine Environmental Research 62 : 380-381

 2006 - PCDD/Fs occurrence in a Mediterranean coastal lagoon (étang de Thau, France): concentrations and patterns in different environmental compartments 

Auteurs : Castro-Jimenez J., Deviller G., Mariani G., Skejo H., Umlauf G., Guiot N., Héas-Moisan K., Léauté F., Munschy C., Tixier C., Tronczynski J.

Organohalogen Compounds, 68, 1016-1021

 Décembre 2006 - Externalities, institutions and the location choices of shellfish producers : the case of blue mussel farming in the Mont-Saint-Michel bay (France) 

Auteurs : Mongruel R., Thébaud O.

 

Most marine aquaculture activities remain strongly dependent on coastal ecosystems. In the case of shellfish farming, this dependency is related mainly to water quality and to the various ecological interactions resulting from the dynamics of coastal food webs. Such ecological constraints have influenced the overall evolution of blue mussel farming in the Mont-Saint-Michel Bay, leading producers to negotiate collective arrangements regarding production capacity and techniques and to develop production strategies at the farm level. This article presents an analysis of the location choices of mussel farmers in the Mont-Saint-Michel Bay based on an empirical investigation conducted in 2002. A typology of farms with respect to their land structure is developed in which some farms choose to concentrate their activity in a single part of the bay while others distribute their activity more widely. Determinants of the location choices of each farm category, including distance to port, natural productivity differentials, and predation of mussel stocks, are analyzed. The role of the institutional arrangements allowing mussel farmers to develop these location strategies is also discussed.

Keywords : blue mussel farming; economic performance indicators; externalities; location choices; institutional arrangements

 Décembre 2006 - In situ QCM DNA-biosensor probe modification. Sensors and Actuators 

Auteurs : Lazerges M., Perrot H., Zeghib N., Antoine E., Compere C.

Sensors and Actuators B Chemical, 120 (1) 329-337 (0.18 Mo) 

We report on a probe modification of a quartz crystal microbalance (QCM) DNA-biosensor that permits to reversibly change the DNA sequence detected. A QCM DNA-biosensor was designed by immobilization of a 20-base DNA-disulfide probe on the gold-covered quartz surface of a 27 MHz microbalance (9 MHz, third overtone). After immobilization on the gold covered quartz surface, this probe was modified by hybridization with a 45-base DNA that includes the complementary 20-base sequence, a 5-base spacer and a non-complementary 20-base sequence. The non-complementary sequence constitutes a new probe, different from the DNA-disulfide probe, that permits the detection of a new DNA target. As this 45 bases DNA is changeable by dehybridization, successive different DNA targets can be detected. Kinetics and thermodynamic studies of the DNA-disulfide and modified biosensors indicate that the modified biosensor is as sensitive, selective, fast, renewable and reproducible as the DNA-disulfide biosensor, but with a higher hybridization ratio. This modification method offers wider investigation field and practical and economic advantages to DNA-biosensors based on irreversible immobilization of DNA probes on solid substrate. (c) 2006 Elsevier B.V. All rights reserved.

Keywords : QCM, Biosensor, DNA

 Décembre 2006 - Preliminary results of the oil spill impact on Lebanese coastal waters 

Auteurs : Khalaf G., Nakhlé K., Abdou-Abi Saab M., Tronczynski J., Mouawad R., Fakhari M

 

Center for Marine Sciences (CNSM) - National Council for Scientific Research in Lebanon (CNRS), and in coordination with Ifremer-France, began the rapid assessment plan in order to evaluate the direct impact of pollution by hydrocarbons on the whole marine ecosystem.
The CNSM has carried out several excursions on field and has also conducted detailed submarine cartography of the polluted sites. The fuel oil, which reached the coast of Batroun, is being sampled and analyzed every 15 days. These analyses have allowed us to determine the degree of alteration and the chemical composition of the fuel oil.
In this study the preliminary results issued from the campaign between July and October 2006 concerning the chemical and biological parameters are presented. Many comparisons are made with pre-spill data obtained from the same period in previous years.
Surface water samples obtained from 14 sites along the Lebanese coast showed relatively high concentrations of nitrates and nitrites ions 2 months after the oil spill, compared to previous years.
Primary production evaluated by counting the phytoplankton population abundance (3 sites), and the measurement of chlorophyll a concentration (13 sites), showed a serious qualitative and quantitative impact in the 2 months following the oil spill.
The specific diversity and the meiofaunal population abundance studied in the Antelias sandy beach site were negatively affected.
Analyses of PAHs levels in 5 species of fish captured in 3 different sites and in the tissues of a mussel species (Brachidontes variabilis) collected in 3 other sites, showed the different responses of the two organisms. The mussel tissues were heavily contaminated, while the fish muscle did not show significant contamination levels.

Keywords : Lebanon, Jieh oil spill, PAHs, coastal water, chemical contamination, nutrients, primary production, meiofauna, fish, bioindicators

 Décembre 2006 - Immobilization of Protein A on SAMS for the elaboration of immunosensors 

Auteurs : Briand E.,Salmain M,Compère C., Pradier-C.M.

Colloids and Surfaces B Biointerfaces; 53 (2) 215-224 (0.34 Mo) 

Binary mixtures of 11-mercaptoundecanoic acid (MUA) and other thiols of various lengths and terminal functions were chemisorbed on gold-coated surfaces via S-Au bonds to form mixed self-assembled monolayers (SAMs). Several values of the inole fraction of MUA in the thiol mixtures were tested and the structure and composition of the resulted thin films were characterized by X-ray photoelectron spectroscopy (XPS) and polarization modulation infrared reflection-absorption spectroscopy (PM-IRRAS). The results made it clear that co-adsorption of MUA with thiols of similar chain length led to well-ordered monolayers whereas the co-adsorption of MUA with shorter thiols yielded less crystalline-like thin films, but with more reactive carboxylic acid terminal groups. This criterion appeared decisive for efficient covalent binding of Stapkylococcus aureus Protein A (PrA), a protein that displays high affinity for the constant fragment (Fc) of antibodies of the IgG type from various mammal species. The ability of immobilized Protein A to recognize and bind a model IgG appeared to be optimal for the mixed SAM of MUA and the short-chain, omega-hydroxythiot 6-mercaptohexanol in the proportion 1-3. (c) 2006 Elsevier B.V. All rights reserved.

Keywords : Protein-A, Antibody, PM-IRRAS, Self-assembled-monolayers, Gold

 Décembre 2006 - Predictive modelling of coastal habitats using remote sensing data and fuzzy logic: A case for seaweed in Brittany (France) 

Auteurs : Eric De Oliveira (LNHE - EDF R&D) , Jacques Populus, Brigitte Guillaumont (Ifremer)

EARSeL eProceedings (European Association of Remote Sensing Laboratories) 2006/12, 5 (2) : 208-223 (1,23 Mo) 

The aim of this study is to model the seaweed species distribution with respect to environmental parameters. We focused on fixed species of algae, such as fucoids. Firstly, we identified environmental parameters, such as substratum nature, immersion time, exposure, etc., which determine the seaweed distribution. Secondly, we used field sampling to compute the distribution laws for seaweed according to the environmental parameters selected. Thirdly, we used the distribution laws and the environmental parameters to perform predictive mapping of seaweed belts with a fuzzy logic method.
Seaweed presence is directly dependent on the nature of the substratum. In the intertidal domain we used an alternative, because seaweed beds can be observed directly. We detected seaweed presence with Spot satellite imagery. The second parameter is immersion time. For each elevation value (surveyed by Lidar), we converted water tidal levels into annual percentages of immersion. The third environmental variable used was exposure to waves. During the fixation phase, seaweeds cannot withstand high levels of exposure. We used a model of wave propagation to delineate areas with different exposure levels.
The presence of seaweed species for each parameter was estimated from field sampling, along with 3D measurements (dGPS). Higher and lower limits of dominant seaweed belts were contoured. With reference to the three environmental variables selected, the distribution laws for each seaweed species were estimated.
A classification by fuzzy logic was applied using eCognition software. Two phases were used in this method: the first phase involved segmentation to obtain polygons, each polygon being homogenous in terms of the environmental parameters selected: vegetation cover, immersion time and exposure level. During the second phase, the distribution laws estimated from field sampling were implemented and finally a membership value was calculated for each targeted species and the results were discussed.

 Novembre 2006 - In vitro test-based comparison of pesticides-induced sensitivity in marine and freshwater phytoplankton 

Auteurs : Arzul G., Quiniou F., Carrié C.

Toxicology mechanisms and methods 16, 431-437.

This study aims to assess the effects of two pesticides, namely the insecticide carbofuran and the herbicide isoproturon, on monospecifically cultivated marine and freshwater phytoplankton according to standard methods. In the presence of pesticide, growth rates were lower in marine species Chaetoceros gracilis and Phaeodactylum tricornutum than in freshwater species Chlorella vulgaris and Selenastrum capricornutum after 72 hours. The EC50 values were obtained with the REGTOX Macro software, and the NEC values by applying the DEBtox model.

Keywords :  DEBtox model, Freshwater phytoplankton, Marine phytoplankton, Pesticides, REGTOX Macro

 Novembre 2006 - The biogeochemistry of mercury at the sediment water interface in the Thau lagoon. 1. Partition and speciation 

Auteurs : Bogdan Muresan Paslaru, Daniel Cossa (Ifremer) , D. Jézéquel (UMR CNRS 7047 - Université D. Diderot & IPGP) , F. Prévot (UMR CNRS 7047 - Université D. Diderot & IPGP) , S. Kerbellec (Ifremer)

Estuarine and Coastal Marine Science (Elsevier) sous presse (0,53 Mo) 

Solid sediment, pore and epibenthic waters were collected from the Thau lagoon (France) in order to study the post depositional partition and mobility of mercury and monomethylmercury in an organic rich sediment. Total Hg (HgT) and monomethymercury (MMHg) profiles were produced in both dissolved and solid phases. The distribution of HgT in the solid appeared to be related to the historical changes in the Hg inputs into the lagoon. HgT was in equilibrium between solid and solution in the sulfidic part of the cores, with a mean log Kd of 4.9 +- 0.2. The solid appeared to be a source of HgT for pore water in the upper oxic to suboxic parts of the cores. The MMHg represented a small fraction of HgT: 3-15 % and 0.02-0.80 % in the dissolved and in the solid phases respectively. Its distribution was characterized by a main peak in the superficial sediments, and another deeper in the core within the sulfide-accumulating zone. In addition, high dissolved MMHg concentrations and methylated percentage were found in the epibenthic water. Ascorbate (pH 8) dissolution of the sediments and analyses of the soluble fraction suggest that the amorphous oxyhydroxides played a major role in controlling total and methylmercury mobility throughout the sediment water interface. These features are discussed in term of sources, transfer and transformations. Diffusive fluxes of HgT and MMHg from sediment to the water column for the warm period were estimated to be 40 +- 15 and 4 +- 2 pmol m-2 d-1 respectively.

 Septembre 2006 - Building of an immunosensor : How can the composition and structure of the thiol attachment layer affect the immunosensor efficiency ? 

Auteurs : Elisabeth Briand (a), Michèle Salmain (b), Jean-Marie Herry (c), Hubert Perrot (d),
Chantal Compere (e), Claire-Marie Pradier (a)

a) Laboratoire de Réactivité de Surface, UMR CNRS 7609, Université Pierre et Marie Curie, 4 Place Jussieu, 75252 Paris Cedex 05, France
b) Laboratoire de Chimie et Biochimie des Complexes Moléculaires, UMR CNRS 7576, Ecole Nationale Supérieure de Chimie, 11 Rue Pierre et Marie Curie, 75231 Paris Cedex 05, France
c) Unite de Bioadhesion et d’Hygiène des Matériaux, INRA 91300 Massy France
d) Laboratoire des Interfaces et Systemes Electrochimiques, UPR 15, Case 133, 4 place Jussieu, 75252 Paris Cedex 05, France
e) Département Essais et Recherches Technologiques, Interface et Capteurs, IFREMER, Centre de Brest, BP 70, 29280 Plouzané, France

Biosensors and Bioelectronics (Elsevier), 2006/09, Volume 22, Issue 3, Pages 440-448 (0,48 Mo) 

Immunosensors, based on the immobilization of a model rabbit antibody on mixed self-assembled monolayers and ProteinAas a linking agent on gold transducers, were elaborated and characterized at each step by modulated polarization-infrared spectroscopy (PM-IRRAS) and occasionally by atomic force microscopy (AFM) and quartz crystal microbalance (QCM). By testing two different mixed SAMs comprising 11-mercaptoundecanoic acid (MUA), together with either decanethiol (C9CH3) or mercaptohexanol (C6OH), the role of the chemical composition and structure of the antibody attachment layer upon the sensor performance was demonstrated.

Contact : Chantal.Compere@ifremer.fr et auteurs

 Septembre 2006 -  Hydrocarbon pollution along Moroccan coasts and BPH activity in the mussel Perna perna. Polycyclic Aromatic Compounds 

Auteurs : Azdi M., Moukrim A., Burgeot T., Budzinski H., Chiffoleau J.F., Kaaya A., Zekhnini A., Narbonne J.F., Garrigues P.

Polycyclic Aromatic Compounds, 26,issue 4, 265–282

Specimens of the mussel Perna perna were collected along Moroccan coasts to determine the concentrations of polycyclic aromatic hydrocarbons (PAHs) bioaccumulated in the tissues, and to measure benzo[ a]pyrene hydroxylase (BPH) activity. Chemical analysis of PAHs show that the Mediterranean (Nador, Martil, Tanger) and central Atlantic coasts (from Rabat to Jorf Lihoudi) are those most contaminated (351 245 ng.g- 1 dry weight in Tanger). The mussel contaminants were of mixed origin for most of the locations with non negligible inputs of petrogenic origin in many of them. Baseline levels of PAHs were between 6 and 55 ng.g- 1 dry weight. BPH activity showed significant correlation (r s = 0.64, P < 0.05) with total PAH concentrations at the six most contaminated stations. The baseline level of BPH activity can be identified as in the range 0.1 to 13 pmol.min- 1.mg prot- 1 along the Mediterranean and Atlantic coasts.

Keywords : mussel, Perna perna; Moroccan coasts, polycyclic aromatic hydrocarbons, benzo[ a]pyrene hydroxylase, baseline level

 Septembre 2006 - Uptake and accumulation of ammonium by Alexandrium catenella during nutrient pulses 

Auteurs : Y. Collos (UMR CNRS 5119, Université Montpellier II), M. Lespiliette (UMR CNRS 5119, Université Montpellier II) , A. Vaquer (UMR CNRS 5119, Université Montpellier II), Mohamed Laabir (UMR CNRS 5119, Université Montpellier II), Annie Pastoureaud (Ifremer)

African Journal of Marine Science (NISC South Africa) 2006/09, 28 (2) : 313-318)

Field observations in Thau Lagoon, southern France, indicate that the growth of natural populations of Alexandrium catenella during blooms is limited by nitrogen and exhibits a storage rather than a growth response to an ammonium pulse. Therefore, ammonium uptake and accumulation under transient conditions were investigated in detail in laboratory cultures. Following nitrogen exhaustion from the medium, ammonium pulses of varying magnitudes were induced, and measurements of extra- and intra-cellular ammonium were carried out for 24-72h along with measurements of ammonium incorporation (N-15 tracer) and inorganic carbon fixation (C-13 tracer). During vegetative growth, values of intra-cellular ammonium reached 30% (Strain TL01) and 2% (Strain ACT03) of cell nitrogen. When ammonium was available in the culture medium, ammonium uptake estimated by the N-15 tracer technique accounted for only 65% of the decrease in external ammonium. This discrepancy is probably due to organic nitrogen excretion. Once external ammonium was exhausted, the observed isotopic dilution of both C-13 and N-15 cell content indicated uptake of a compound containing both unlabelled carbon and nitrogen atoms.

 Septembre 2006 - Building of an immunosensor : How can the composition and structure of the thiol attachment layer affect the immunosensor efficiency ? 

Auteurs : Elisabeth Briand (a), Michèle Salmain (b), Jean-Marie Herry (c), Hubert Perrot (d),
Chantal Compere (e), Claire-Marie Pradier (a)

a) Laboratoire de Réactivité de Surface, UMR CNRS 7609, Université Pierre et Marie Curie, 4 Place Jussieu, 75252 Paris Cedex 05, France
b) Laboratoire de Chimie et Biochimie des Complexes Moléculaires, UMR CNRS 7576, Ecole Nationale Supérieure de Chimie, 11 Rue Pierre et Marie Curie, 75231 Paris Cedex 05, France
c) Unite de Bioadhesion et d’Hygiène des Matériaux, INRA 91300 Massy France
d) Laboratoire des Interfaces et Systemes Electrochimiques, UPR 15, Case 133, 4 place Jussieu, 75252 Paris Cedex 05, France
e) Département Essais et Recherches Technologiques, Interface et Capteurs, IFREMER, Centre de Brest, BP 70, 29280 Plouzané, France

Biosensors and Bioelectronics (Elsevier), 2006/09, Volume 22,  

Immunosensors, based on the immobilization of a model rabbit antibody on mixed self-assembled monolayers and ProteinAas a linking agent on gold transducers, were elaborated and characterized at each step by modulated polarization-infrared spectroscopy (PM-IRRAS) and occasionally by atomic force microscopy (AFM) and quartz crystal microbalance (QCM). By testing two different mixed SAMs comprising 11-mercaptoundecanoic acid (MUA), together with either decanethiol (C9CH3) or mercaptohexanol (C6OH), the role of the chemical composition and structure of the antibody attachment layer upon the sensor performance was demonstrated.

Contact : Chantal.Compere@ifremer.fr et auteurs

 Août 2006 - Are growth and density quantitative indicators of essential fish habitat quality? An application to the common sole Solea solea nursery grounds   

Auteurs : Camille Gilliers (Université de Lille I) , Olivier Le Pape (Agrocampus Rennes) , Yves Desaunay (Ifremer) , Jocelyne Morin (Ifremer) , Daniel Guerault (Ifremer) , R Amara (Université du Littoral Côte d'Opale)

Estuarine, Coastal and Shelf Science (Elsevier) 2006/08, 69 (1-2) : 96-106 (0,26 Mo) 

Bio-indicators were measured on juvenile fish to assess the quality of eight coastal and estuarine nursery grounds in the Eastern English Channel and in the Bay of Biscay during 3 years. Growth (size and otolith daily increment width), body condition (morphometric index) and abundance of juvenile common soles were analysed together with xenobiotic concentrations (heavy metals and organic contaminants).
Condition indices displayed important variations and did not allow relevant estimation of environmental quality. On the contrary, growth and density indicators showed good steadiness above years but varied among sites. In spite of difficulties of interpreting these indicators on such a meso-scale approach, analyses highlighted the estuaries of Seine and Gironde. In these nursery areas, the levels of contamination were especially high, and the combination of fish growth performances and density was significantly lower than in other sites. The combination of these variables appears to provide reliable indicators of habitat quality and anthropogenic pressure on nursery grounds, especially highlighting contaminated areas. Such indicators may thus contribute to improve assessment of environmental quality of essential fish habitats with the aim of a sustainable management of fisheries resources. A study at a different scale, from this meso-scale nursery approach with more precise analyses, on local habitats, will nevertheless be necessary to optimize the relevance of these indicators for the assessment of essential fish habitat quality. (c) 2006 Elsevier Ltd. All rights reserved.

 Août 2006 - Tidally-induced shear stress variability above intertidal mudflats in the macrotidal Seine estuary 

Auteurs : Romaric Verney (Ifremer), J. Brun Cottan (University of Caen), R. Lafite (University of Rouen), J. Deloffre (University of Rouen), J. Taylor (Coastal and Estuarine Research Group, University of Sussex, Brighton, UK)

Estuaries and coasts (Estuarine Research Federation) 2006/08, 29 (4) : 653-664 (0,66 Mo) 

Tidal currents and the spatial variability of tidally-induced shear stress were studied during a tidal cycle on four intertidal mudflats from the fluvial to the marine part of the Seine estuary. Measurements were carried out during low water discharge (< 400 m(3) s(-1)) in neap and spring tide conditions. Turbulent kinetic energy, covariance, and logarithmic profile methods were used and compared for the determination of shear stress. The c(TKE) coefficient value of 0.19 cited in the literature was confirmed. Shear stress values were shown to decrease above mudflats from the mouth to the fluivial part of the estuary due to dissipation of the tidal energy, from 1 to 0.2 N m-(2) for spring tides and 0.8 to 0.05 N m(-2) for neap tides. Flood currents dominate tidally-induced shear stress in the marine and lower fluvial estuary during neap and spring tides and in the upper fluvial part during spring tides. Ebb currents control tidally-induced shear stress in the upper fluvial part of the estuary during neap tides. These results revealed a linear relationship between friction velocities and current velocities. Bed roughness length values were calculated from the empirical relationship given by Mitchener and Torfs (1996) for each site; these values are in agreement with the modes of the sediment particle-size distribution. The influence of tidal currents on the mudflat dynamics of the Seine estuary was examined by comparing the tidally-induced bed shear stress and the critical erosion shear stress estimated from bed sediment properties. Bed sediment resuspension induced by tidal currents was shown to occur only in the lower part of the estuary.

 Juillet 2006 - Assessing the effects of marine protected area (MPA) on a reef fish assemblage in a northwestern Mediterranean marine reserve: Identifying community-based indicators 

Auteurs : Joachim Claudet, Dominique Pelletier (Ifremer) , J.Y Jouvenel (P2A Development) , F. BACHET (Maison de la Mer, Sausset-les-Pins) , R. GALZIN (CNRS-EPHE / Ifremer)

Biological Conservation (Elsevier) 2006/07, 130 (3) : 349-369 (0,29 Mo) 

Marine protected areas (MPAs) are increasingly envisaged as a tool to manage coastal ecosystems and fisheries. Assessment of their performance with respect to management objectives is therefore important. A number of WAS provided conservation benefits for fished species. Observed benefits do not apply to all species at all times, and responses to protection are also highly variable among fish taxa. Among the many empirical studies on marine reserves, only a few designs considered 'before and after data' and spatial variation. In this paper, we are interested in assessing the effect of a no-take reserve on the reef fish assemblage in a northwestern Mediterranean example. Data were obtained from a three-year survey using underwater visual censuses (UVC), before and after MPA establishment. Permutational multivariate analysis of variance (PERMANOVA) and multivariate regression trees (MRT) were used to evaluate the effects of reserve protection on the reef fish assemblage, while accounting for habitat. Modelled biological responses were abundances and diversity indices calculated at different levels of the assemblage. Significant effects were found for many of these metrics. in addition to PERMANOVA, univariate models provided more insight into the magnitude and direction of effects. The most sensitive metrics were related to large species and species targeted by fishing. These results may be used to choose the metrics that are more suitable as community-based indicators of MPA impact in the perspective of monitoring programs. (c) 2006 Elsevier Ltd. All rights reserved.

 Juillet 2006 - Observation and modelling of natural retention structures in the English Channel  

Auteurs : Alain Ménesguen et Francis Gohin (Ifremer)

Journal of Marine System (volume 62, 3&4)  

Accumulation of heat, or dissolved substances (nutrients, pollutants, etc.), or fine suspended particles in a water body is a key process in the functioning of aquatic ecosystems and their resistance to perturbations. In complex and wide open environments such as marine ecosystems, net accumulation is not only linked to the local renewal capacity of the water body, but also to the partial recirculation of water due to convective cells of various sizes. The English Channel, which can be considered as mainly dominated by tidal movements, exhibits such a complex quasi-permanent long-term circulation, made of a central “river” bordered with a lot of nested gyres. Here, we show that structures visible on satellite images of SST (Sea Surface Temperature), chlorophyll and SPIM (Suspended Particulate Inorganic Matter) can be explained by steady state distributions of tracers having various half-life durations, which can be computed using a simple technique of regularly distributed micro-injection in the permanent flow field. Gyres induced by capes in open water appear to be retention areas, whereas gyres around islands (Channel Isles) appear to be strong disseminating areas, acting as slings. Moreover, SSTsatellite maps can be explained by a short-lived tracer during the “transitory” seasons (spring and autumn), and by a long-lived one during the “stable” seasons (summer and winter): long-term accumulation structures become apparent only in August and March. SPIM can be considered as a tracer injected only in muddy areas by the bottom friction caused by the swell, and having a half-life duration linked to the turbulent energy dissipation, which controls the settling rate; this succeeds to explain the observed turbidity in the central Channel essentially, as well as the striking asymmetry visible on images between the large turbid coastal band along the English coasts (materializing a natural long-term retention area), and the rather clear waters along the French coasts. The annual mean chlorophyll distribution in the Channel, as derived from satellite reflectance, can be simulated by a short-lived tracer injected proportionally to the mean light availability along the water column. Computing steady state distributions of various substances or particles in permanent circulation gives a simple and quick tool for understanding their mean stable distribution patterns in the oceans.

Contacts : Alain.Menesguen@ifremer.fr, Francis.Gohin@ifremer.fr  

 Juillet 2006 - The determination of total dissolved free primary amines in seawater : Critical factors, optimized procedure and artefact correction 

Auteurs : Alain Aminot, Roger Kérouel (Ifremer)

Marine Chemistry (Elsevier) 2006/02, (98 (2-4) : 223-240) (0,29 Mo) 

The paper reviews the methods described in the literature for the determination of total dissolved free primary amines (TDFPA) by fluorescence. A wide set of reaction conditions can be found, but they rely on few experiments for their validation. Among fluorogenic compounds, o-plithaldialdehyde (OPA) is more sensitive than fluorescamine and was thus examined here. However, the use of mercaptoethanol (ME) in the reaction (as ail additional derivatization compound) is able to generate unreliable results, in particular when standardization relies on glycine. We suggest replacing ME with 3-mercaptopropionic acid (MPA) which induces more stable and comparable fluorescence among amine Compounds. A systematic study was therefore undertaken to define reagent concentrations and pH effects on the reaction rates for a variety of primary amines with particular focus on amino acids. The reaction rate is increased by increasing OPA concentration and pH, but slowed by excess MPA. Ammonium interference is influenced by several factors, but spectral investigation showed that the choice of conditions can drastically reduce it. The magnitudes of natural and OPA-induced background fluorescence signals have been assessed in various mediums and it is shown that their contribution to the signal amounts to a large fraction, when not most, of the measured fluorescence. A segmented flow method is proposed with a protocol for adequate correction of biases. (c) 2005 Elsevier B.V. All rights reserved.

Keywords:  Total dissolved free primary amines; Seawater; Determination; Fluorescence

 Mars 2006  - Seasonal evolution of the nutrient pattern on Biscay Bay continental shelf over the years 1999-2000 

Auteurs : Loyer S., Lampert L., Ménesguen A.,

Scientia Marina (Institut de Ciències del Mar de Barcelona, CSIC), 2006/03, Volume 70, Issue 1, Pages 31-46 

The French Atlantic shelf is Subjected to strong anthropic influences (urban, industrial and agricultural discharges) of two main rivers (Loire and Gironde). The extension and consequences of these continental loadings for the nutrient and chlorophyll distribution have never been studied before oil the Bay of Biscay continental shelf as a whole. We present the first synoptic view of the nutrient distribution and evolution oil the French Atlantic shelf. Nutrient concentrations of the surface layer were Studied during four cruises in April, June, September 1999 and March 2000. Until June, the freshwater inputs induce a nitrate gradient from river months to offshore waters in the vicinity of the 100 m isobath. The Redfield's ratio Study highlights the nitrate excess in river loadings. The early spring situation is characterised by high N:P ratios in front Of file two estuaries and by a potential Si-limitation in the northern part. Nitrate removal continues in spite of the P-limitation and the increase in silicate concentrations during summer supposes high regeneration processes. At the end of summer, the water column is thermally stratified and the Surface mixed layer is totally depleted in nitrate.

Keywords : Bay-of-Biscay, Coastal-water, River-inputs, Nutrients

 Mars 2006 - Modelling water discharges and nitrogen inputs into a Mediterranean lagoon - Impact on the primary production 

Auteurs : Martin Plus (Ifremer) , I. La Jeunesse (Université Catholique de Louvain) , F. Bouraoui (JRC, IES-Inland and Marine Waters Unit, Italy) , J. Zaldivar (JRC, IES-Soil and Waste Unit, Italy) , Annie Chapelle (Ifremer) , Pascal Lazure (Ifremer)

Ecological Modelling (Elsevier) 2006/03, 193 (1-2) : 69-89 (0,91 Mo) 

The Soil and Water Assessment Tool (SWAT model, 2001 Version) has been applied to the Than lagoon catchment area in order to simulate water discharges and nutrient inputs into the lagoon over a 10 years period (1989-1999), and to provide routing inflows to a previously developed lagoon ecosystem model. The watershed model has been calibrated and validated using measured data available for the two main rivers. The results indicate that the mean annual nitrogen inputs into the Thau lagoon is 117 +/- 57 tons y(-1), with the two main rivers, contributing for 80% of total annual nitrogen export. The variations of outputs to the lagoon are nonetheless important from 1 year to another. Due to the local agricultural practices and a reduced in-stream natural depuration, point sources seem to be the main factor affecting the fresh water quality.
The coupling with the lagoon model allowed to estimate the impact of those terrestrial inputs on the lagoon nitrogen cycling and primary productivity. Influence of river discharges makes itself felt essentially near the river outlets. The northern bordure of the lagoon is then characterised by highly variable dissolved inorganic nitrogen concentrations, especially during flood events, while more stable and lower concentrations were simulated in the southern part of the lagoon. Simulated chlorophyll a ranged 1-15 mu g l(-1), with maximums in March. Mean annual phytoplankton production was 364 +/- 142 gC m(-2). The simulations showed that maximum annual productions are due to macrophytes (up to 1300 gC m(-2) y(-1)), but at the whole lagoon scale, annual phytoplankton production resulted greater. From our results it also appeared that the greatest part of primary producers nitrogen requirements is satisfied by nutrient regeneration within the lagoon.

 Mars 2006 - A probabilistic approach of flow-balanced network based on Markov chains 

Auteurs : Delphine Leguerrier (Univ. La Rochelle), Cédric Bacher (Ifremer), Eric Benoit et Nathalie Niquil (Univ. La Rochelle)

Ecological Modelling (Elsevier) (2006/03, 193 (3-4) : 295-314) (0,63 Mo) 

We used Markov chains to assess residence time, first passage time, rare of transfers between compartments, recycling index with a general mathematical formalism. Such a description applies to any flow-balanced system that can be modelled as a series of discrete stages or compartments through which matter flows. We derived a general set of equations from a probabilistic approach and applied them to a food web and a physical system derived from the literature. We therefore analysed preferential pathways of matter and behaviour of these systems and showed how it was possible to build up and exploit indices on the basis of a transition probability matrix describing the network, and to characterize with a generic algorithm: (1) the total indirect relationships between two compartments, (2) (he residence time of one compartment and (3) the general recycling pathways including the amount of matter recycling and the implication of each compartment in recycling. (C) 2005 Elsevier B.V. All rights reserved.

 Janvier 2006 - A new numerical technique for tracking chemical species in a multi-source, coastal ecosystem, applied to nitrogen causing Ulva blooms in the Bay of Brest 

Auteurs : Ménesguen A., Cugier P., Leblond I.

Limnologie and oceanography (ASLO), 2006/01, Volume 51, Issue 1 (part 2), Pages 591-601

A new numerical technique is presented that allows the tracking of any chemical element from any source in a simulated foodweb, for instance assessing the proportion of these sources (river loadings, sea entrances, point sources) in the algal diet for the limiting nutrient. An application is shown for nitrogen in an Ulva bloom occurring in a shallow embayment connected with a strongly tidally stirred ecosystem with various sources of inorganic nitrogen, the Bay of Brest, Brittany, France. In a first step, a biogeochemical three-dimensional model was developed to simulate growth and erosion-transport-deposition of free-floating ulvae; this model was able to converge on a realistic distribution of Ulva deposits after a few months, even though it was initialized with a strongly unrealistic distribution of settled ulvae. In a second step, and unfortunately for recovery plans, the tracking technique, applied in this model to all the nitrogen sources entering the bay, revealed that the small, nitrate-polluted rivers flowing directly into the eutrophicated area had a negligible effect, whereas more distant but stronger sources, a big river and a big urban sewage plant, even after dilution, accounted for about 50% and 20%, respectively, of the algal nitrogen content during summer. Despite its high N flux, open ocean contributes only 15% to Ulva growth. The suppression of only one of the main nitrogen sources would not significantly decrease the Ulva bloom, because of the high nitrogen surplus present in the site. The remaining sources would still saturate the needs of the maximum Ulva biomass the site is able to produce. The tracking technique, however, shows that the N turnover in Ulva is only 4 months. Thus, improvements would occur within a year following large N reductions.

 Janvier 2006 - Pollutant effects on Pacific oyster, Crassostrea gigas (Thunberg), hemocytes: screening of 23 molecules using flow cytometry 

Auteurs : Gagnaire B., Thomas Guyon H., Burgeot T ., Renault T.

Cell Biology and Toxicology 22 : 1-14 (0.39 Mo) 

The shellfish industry is an important economic activity in France, occurring mostly in estuarine zones subject to pollution due to anthropogenic activities. The harmful effects of pollutants on species inhabiting these estuarine zones are not well known. Among marine species, bivalve mollusks---particularly Pacific oyster, Crassostrea gigas-may serve a model of interest. The species is sedentary and filter-feeding, which favors bioaccumulation of pollutants in their tissues. Oysters may be suitable for studies on disturbance by pollutants of physiological activities, among which defense mechanisms are poorly documented in bivalves. In this study, effects of pollutants on hemocyte functions were monitored in Pacific oyster, C. gigas. Hemocytes were exposed in vitro to selected pollutants. The strategy for investigating the effects of pollutants on hemocyte functions is based on several biomarkers, which is more relevant than that of published papers based on single-endpoint experiments. Pollutants belonging to the most important groups of xenobiotics (PAHs, PCBs, and pesticides) were selected and their effect on hemocyte activities was analyzed using flow cytometry. Twenty-three pollutants were tested and eight of them showed significant modulation of hemocyte activities. PAHs and PCB 77 induced a decrease of hemocyte activity after an incubation periods of 4 and 24 h at 200 mu mol/L. Three pesticides (2,4D, paraoxon, and chlorothalonil) modulated hemocyte activities. A mixture of eight pesticides also decreased phagocytotic activity. This study is one of the first to investigate the effects of so many pollutants on hemocyte functions at the same time and therefore allows a real comparison of different pollutant effects.

Keywords : Hemocytes, Pacific-oyster, Crassostrea-gigas, PAHs, PCBs, Pesticides, Toxicity, Cellular-activities, Flow-cytometry

 Janvier 2006 - Bilan du suivi de l'exploitation industrielle de la crépidule en Bretagne Nord (Baies de Saint-Brieuc et du Mont Saint Michel) 2002-2005 

Auteurs : Michel Blanchard et Dominique Hamon

Rapport de fin de contrat Ifremer / Areval, R. Int. Dyneco/EB/06-01, 42 p. + annexes

 Janvier 2006 - The influence of sediment cohesiveness on bioturbation effects due to Hydrobia ulvae on the initial erosion of intertidal sediments: A study combining flume and model approaches  

Auteurs : Francis Orvain (CREMA , Pierre-Guy Sauriau (CNRS-IFREMER, UMR 10), Cédric Bacher (Ifremer), M. Prineau (CNRS-IFREMER, UMR 10)

Journal of Sea Research (55, 54-73) 

Laboratory experiments performed in a recirculating flume were designed to quantify the bioturbation influence of the mud snail Hydrobia ulvae, one of the most abundant deposit feeders on European intertidal mudflats. Variations in sediment moisture content that occur between bedforms in shore-normal, ridge and runnel systems of intertidal mudflats were added to the model definition. Sediment erosion thresholds, erosion rates and the microalgal pigment composition of resuspended material were quantified for different H. ulvae densities (0, 1000, 5000, 10 000 and 50 000 snails m- 2) and applied bed shear stresses. Two different sediment moisture contents were tested. In the absence of macrofauna, recorded turbidities increased up to the maximum applied value of 1.6 Pa and the addition of snails increased the resuspended mass at all bed shear stresses tested. The amount of resuspended mass depended on snail density; the amount of resuspended material was highest in sediment test beds that had the highest moisture contents (ridge-type sediments) and snail density. Resuspended and bioturbated sediment was characterised by an enrichment in phaeopigments compared to the underlying sediment. A nine-parameter model, which included sediment moisture content as a new variable, gave a reasonably good estimate of the resuspension of ridge- and runnel-type sediments for the range of snail densities. An eight-parameter version of the model was adequate for quantifying erosion rates on intertidal mudflats not characterised by a ridge/runnel geomorphology.

Keywords: Resuspension; Bioturbation; Hydrobia ulvae; Sediment; Mudflat; Ridges and runnels; Chloropigments; Flume; Model

 Janvier 2006 - Oligonucleotide quartz crystal microbalance sensor for the microalgae Alexandrium minutum ( Dinophyceae) 

Auteurs : Lazerges M., Perrot H., Antoine E., Defontaine A., Compere C.

Biosensors and Bioelecronics. 21, 7, 355-1358 (0.08 Mo) 

We report the immobilization on a gold surface of a 20-base DNA probe labeled with disulfide group and on the selective hybridization with the complementary 20-base DNA strand. The oligonucleotide probe is the complementary strand of a partial sequence of the gene encoding for a large ribosomal RNA sub-unit which is a coding sequence of Alexandrium minutum DNA, a microalgae that produces neurotoxins responsible for paralytic shellfish poisoning on European and Asian coasts. The kinetics of DNA probe immobilization and hybridization were monitored in situ by using a 27 MHz quartz crystal microbalance under controlled hydrodynamic conditions. The frequency of the setup is stable to within a few hertz, corresponding to the nanogram, scale, for 3 h and makes it possible to follow frequency change from immobilization of the probe to hybridization of the complementary DNA target. This setup constitutes a biosensor, which is sensitive and selective, and the hybridization ratio between hybridized complementary DNA and immobilized DNA probes is 47%.

Keywords : Microbalance, Alexandrium-minutum, DNA

 Janvier 2006 - A pollution-monitoring pilot study involving contaminant and biomarker measurements in the Seine Estuary, France, using zebra mussels ( Dreissena polymorpha) 

Auteurs : Christophe Minier (Université du Havre), Alain Abarnou (Ifremer), Agnès Jaouen Madoulet (Université du Havre) , Anne-Marie Le Guellec (Ifremer)

Environmental Toxicology and Chemistry (SETAC) 2006/01, 25 (1) : 112-119 (0,26 Mo) 

Zebra mussel ( Dreissena polymorpha) is an invasive species that has proliferated in European and North American rivers and lakes during the last century. In this study, D. polymorpha has been used to provide information on contamination levels and biological effects in the Seine Estuary (France). The bivalves accumulated polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) to a high degree with values reaching 800 ng/g dry weight for PCBs (sum of 20 congeners), and 1,000 ng/g dry weight of PAHs (sum of 14 compounds) in the whole body. These values are among the highest reported of PCBs and, to a lesser extent, of PAHs in other contaminated areas in the world. Toxic equivalent quantities of PCBs and PAHs detected in zebra mussels varied from 20 to 40 pg dioxin equivalents/g dry weight for PCBs and up to 120 ng benzo[alpha]pyrene equivalents/g dry weight for PAHs, indicating a high potential risk for animals feeding on them. Biological impacts, such as altered condition index, decreased lysosomal stability, and high levels of multixenobiotic resistance (MXR) proteins also were detected in mussels living downstream of Rouen, the main city of the Seine Estuary. Taken together, these results indicate that the Seine Estuary is a heavily polluted area with the potential to cause deleterious health effects in some endogenous living organisms. This study also shows that chemical and biological measurements bring different but complementary results that can help diagnose environmental health.

 Janvier 2006 - Preliminary estimate of primary production by phytoplankton in Marennes-Oleron Bay, France 

Auteurs : Caroline Struski, Cédric Bacher (Ifremer)

Estuarine, Coastal and Shelf Science, (66, 323-334) (0,47 Mo) 

The macrotidal bay of Marennes-Oléron is the most important French site for shellfish production (oysters and mussels); yet the primary productivity of the phytoplankton compartment in this system is not well known. In this study, photosynthetic parameters were determined using 14C incubations of bottom and surface water samples, during fall, winter and summer (2001-2002), along a north/south transect in the bay. Estimates of primary productivity showed that water column primary production is light-limited in the bay and that a BZpI0 type model can be applied. Spatial differences existed in the bay, with a more productive northern zone and less productive river area. With a water column primary production of 185 g C m-2 yr-1, Marennes-Oléron Bay lies in the mean range for phytoplankton primary production capacity among European and North American estuaries.

Keywords:  photosynthesis parameters; phytoplankton; turbidity; light limitation; tidal bay; BZp I0 model

 Janvier 2006 - Role of particle sorption properties in the behavior and speciation of trace metals in macrotidal estuaries: The cadmium example 

Auteurs : Jean-Louis Gonzalez, Benedicte Thouvenin, Catherine Dange, Jean-Francois Chiffoleau, Bernard Boutier (Ifremer)

The Handbook of Environmental Chemistry (Springer Berlin / Heidelberg) 2006/01, 5H (-) : 265-301 (2,01 Mo) 

The role of particles in the fate and speciation of trace metals in macrotidal estuaries was studied using a surface complexation model (MOCO). Cadmium was selected as the target metal contaminant due to its reactivity in estuaries: cadmium behavior is mainly controlled by heterogeneous processes (sorption/desorption) related to salinity and suspended matter gradients.
Various scenarios of suspended matter distribution according to salinity were simulated. The impact of surface properties (specific surface area, density of surface sites, acido-basic properties, and complexation constant) was evaluated using data collected on particles from the Gironde, Loire, and Seine estuaries.
Our results show that particle surface properties, evaluated on the basis of various parameters, are instrumental in "non-conservative" contaminant speciation in the estuarine environment. Their evaluation enables us to understand and simulate, to a large extent, the fate of "Cd-type" contaminants (whose behavior is controlled by competition between sorption and desorption processes). The natural variations of these properties can be responsible for significant modifications of the Cd speciation in the macrotidal estuaries where salinity and SM gradients are very strong.