Éditeur(s) : Tahiti Aquaculture 2010, 6-11 décembre 2010

Droits : Tahiti Aquaculture 2010
http://archimer.ifremer.fr/doc/00063/17413/14920.pdf
http://archimer.ifremer.fr/doc/00063/17413/

Résumé : The study conducted in the framework of an agreement between Ifremer and the Local fisheries committee at Audierne is part of a project to restore spiny lobster Palinurus elephas stock levels in the Iroise Sea. It is supported by professional fishermen from Finistère and by the Regional fisheries committee of Brittany. After a brief review of the way lobster stocks are managed worldwide, followed by the major biological and ecological features of red lobster and the state of fisheries in Europe and North Africa, the very poor state of the resource along French coast is borne out by the statistics of landings. Various scenarios (not alternatives) to promote the rebuilding of the biomass are suggested: minimum landing size increase, seasonal closure of the fishery, berried females protection, no fishing zones. The drift of phyllosoma larvae during their long larval stage is addressed using a 3-D hydrodynamic simulation model.
L'étude réalisée dans le cadre d'une convention entre Ifremer et le Comité local des Pêches d'Audierne s'inscrit dans un projet de reconquête des niveaux de ressource en langouste rouge Palinurus elephas en mer d'Iroise soutenu par les pêcheurs professionnels de la pointe du Finistère et par le Comité régional des Pêches de Bretagne. Après avoir rappelé brièvement les modalités de gestion des stocks de langoustes dans le monde puis les grands traits biologiques et écologiques de la langouste rouge et l'état des pêcheries en Europe et dans le nord de l'Afrique, le très mauvais état de cette ressource sur les côtes françaises est confirmé au travers des statistiques de débarquement. Divers scénarios (non alternatifs) visant à favoriser la reconstitution d'une biomasse sont proposés : augmentation de la taille minimale au débarquement, fermeture saisonnière de la pêche, protection des femelles ovigères et création de zones protégées. La dérive des larves phyllosomes au cours de leur longue phase larvaire est abordée par un modèle de simulation hydrodynamique en trois dimensions.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/2005/rapport-1198.pdf
http://archimer.ifremer.fr/doc/00000/1198/

Éditeur(s) : Elsevier
Résumé : A coupled three-dimensional physical-biogeochemical model was developed in order to simulate the ecological functioning of the Rio de la Plata estuary and plume. The biogeochemical model reproduces the nitrogen cycle between five compartments: dissolved inorganic nitrogen, phytoplankton, zooplankton, detritus and dissolved organic nitrogen. The coupling is tested in seasonal climatological configurations and for the particular year 1999. The circulation is forced with Parana and Uruguay rivers discharges, NCEP wind and tide. The biogeochemical model includes loads of inorganic and organic nitrogen from both rivers. The model reproduces the correct tidal amplitudes in the estuary, as well as the most outstanding features of the observed horizontal and vertical structures of the salinity plume. Simulated surface chlorophyll a concentrations exhibit maximum values all year long seaward of the turbidity front, between the 0.5 and 15 isohalines, in agreement with SeaWiFS images of the area. The model simulates well the low primary production in the light-limited highly turbid tidal river (20 gC/m(2)/yr), the high production area in the frontal zone where it can reach 500 gC/m(2)/yr, and the nutrient-limited production in the outer estuary and inner shelf (300 gC/m(2)/yr), with realistic values in each case. According to the 1999 model simulation, the tidal river is the location of organic nitrogen remineralization with a consequent increase of the inorganic pool. At the entrance of the frontal zone, inorganic nitrogen represents about 75% of the whole nitrogen pool, it is reduced to 50% at its sea end-member. The outer estuary has the same sink role for inorganic nitrogen, suggesting that organic nitrogen is the major form exported to the shelf.
Continental Shelf Research (0278-4343) (Elsevier), 2005-03 , Vol. 25 , N. 5-6 , P. 629-653

Droits : 2004 Elsevier Ltd.
http://archimer.ifremer.fr/doc/2005/publication-334.pdf
DOI:10.1016/j.csr.2004.10.003
http://archimer.ifremer.fr/doc/00000/334/

Éditeur(s) : IEEE
Résumé : This paper aims at studying the quality of the sea surface salinity (SSS) retrieved from soil moisture and ocean salinity (SMOS) data in coastal areas. These areas are characterized by strong and variable SSS gradients [several practical salinity units (psu) on relatively small scales: the extent of river plumes is highly variable, typically at kilometric and daily scales. Monitoring this variability from SMOS measurements is particularly challenging because of their resolution (typically 30-100 km) and because of the contamination by the nearby land. A set of academic tests was conducted with a linear coastline and constant geophysical parameters, and more realistic tests were conducted over the Bay of Biscay. The bias of the retrieved SSS has been analyzed, as well as the root mean square (rms) of the bias, and the retrieved SSS compared to a numerical hydrodynamic model in the semirealistic case. The academic study showed that the Blackman apodization window provides the best compromise in terms of magnitude and fluctuations of the bias of the retrieved SSS. Whatever the type of vegetation cover, a strong negative bias, greater than 1 psu, was found when nearer than 36 km from the coast. Between 44 and 80 km, the type of vegetation cover has an impact of less than a factor 2 on the bias, and no influence further than 80 km from the coast. The semirealistic study conducted in the Bay of Biscay showed a bias over ten days lower than 0.2 psu for distances greater than 47 km, due to an averaging over various geometries (coastline orientation, swath orientation, etc.). The bias showed a weak dependence on the location of the grid point within the swath. Despite the noise on the retrieved SSS, contrasts due to the plume of the Loire River and the Gironde estuary remained detectable on ten-day averaged maps with an rms of 0.57 psu. Finally, imposing thresholds on the major axis of the measurements brought little improvement to the bias, whereas it increased the rms and- could lead to strong swath restriction: a 49-km threshold on the major axis resulted in an effective swath of 800-900 km instead of 1200 km. NOT CONTROLLED OCR
Transactions on geoscience an remote sensing IEEE (0196-2892) (IEEE), 2007-07 , Vol. 45 , N. 7 , P. 2061-2072

Droits : 2007 IEEE
http://archimer.ifremer.fr/doc/2007/publication-3643.pdf
DOI:10.1109/TGRS.2007.894934
http://archimer.ifremer.fr/doc/00000/3643/

Éditeur(s) : XIIèmes Journées Nationales Génie Côtier - Génie Civil. Cherbourg, 12-14 juin 2012. n°12. Levacher D, Sanchez M, et Guillou S (Eds). ISBN 978-2-35921-008-8. Thème 5 : Energies marines. pp.809-818
Résumé : Les fortes vitesses rencontrées à l’entrée de la Baie du Mont Saint-Michel font de cet environnement macro-tidal un endroit privilégié, en termes de ressources énergétiques, pour l’implantation d’une ferme d’hydroliennes. Afin d’établir plus précisément son potentiel énergétique et d’évaluer l’impact de l’implantation de telles machines sur son hydrodynamisme, une modélisation hydrodynamique de la Baie du Mont Saint-Michel est mise en oeuvre à l’aide du modèle de circulation régionale MARS3D (LAZURE & DUMAS, 2008) dans sa version tridimensionnelle. La validation hydrodynamique de cette configuration est réalisée à partir de comparaisons à des mesures courantologiques récentes (KERVELLA, 2010). A partir de cette modélisation, une cartographie du potentiel énergétique de la Baie est établie et les endroits propices à l’installation de structures récupératrices de l’énergie des courants sont identifiés. L’impact de l’implantation d’une ou plusieurs structures à l’un de ces endroits sur l’hydrodynamique de la Baie est évalué : l’effet de l’extraction d’énergie des courants est modélisé par l’implémentation d’un nouveau terme puits, correspondant à une force de retard colinéaire à l’écoulement (DEFNE et al., 2011), dans les équations du mouvement de MARS3D. Les résultats présentés pour 2 valeurs d’extraction de l’énergie disponible (25% et 55%) montrent que l’impact d’un parc de petite superficie sur les courants reste très local.

Droits : Editions Paralia CFL
http://archimer.ifremer.fr/doc/00195/30599/29055.pdf
DOI:10.5150/jngcgc.2012.088-B
http://archimer.ifremer.fr/doc/00195/30599/

Éditeur(s) : Mercator Ocean
Résumé : Face to the lack of data to assess precisely the spatial distribution of catches and fishing effort and for the environmental characterization of the fishing area, Ifremer has been implemented since 2005 a new project, Recopesca. It consists in fitting out a sample of voluntary fishing vessels with sensors recording data on fishing effort (and at mid-terms catches) and physical parameters such as temperature or salinity. Recopesca aims at setting up a network of sensors, for scientific purposes, to collect data and improve resources assessment and diagnostics on fisheries, and environmental data required for ecosystem-based management initiatives. The challenge was to develop sensors with no trouble for the fishermen, tough enough to be fixed up on fishing gears, self powered and autonomous. Insofar as the sample of targeted vessels intends to be representative of all the metiers and fleets, the sensors are modular and scalable to collect new data. Different sensors have been implemented: (i) a temperature-salinity sensor, able to record physical parameters, depth and duration of immersion, for passive and active gears, and (ii) a specific sensor to record number or length of passive gears. A GPS monitors the position of the vessels and the temperature or salinity profiles and series. Each sensor is equipped with a radio device transferring the data to a receiver on-board, called “concentrator” that sends the data to Ifremer central databases by GPRS. An anti-rolling weigh-scale has been developed and is currently on test to record catches per species and fishing operation. The presentation will show the first data and results of this participative approach.
Mercator Ocean - Quarterly Newsletter (Mercator Ocean), 2010-04 , N. 37 , P. 40-48

Droits : 2010 Mercator Ocean
http://archimer.ifremer.fr/doc/00024/13500/10514.pdf
http://archimer.ifremer.fr/doc/00024/13500/

Éditeur(s) : Inter-research
Résumé : Benthic primary production and respiration were investigated at 4 sites representative of the major coastal communities bordering the Sahara Desert in the Banc d'Arguin, Mauritania, Western Africa. These sites correspond to intertidal Zostera noltii beds (270 km(2)), intertidal bare sediments (88 km(2)), subtidal Cymodocea nodosa beds (374 km(2)), and subtidal bare sediments (311 km(2)). At each site, production-irradiance relationships were established in situ in November 2008 and January 2010, and used to calculate daily carbon fluxes for these communities. In intertidal areas, compared to emersion, the gross maximal photosynthetic rates for Z. noltii bed and bare sediment communities were on average 8-and 7-fold higher during immersion, respectively; community respiration rates were 3-and 18-fold higher during immersion, respectively. The Z. noltii bed was autotrophic during the 2 study periods, with a mean (+/- 95% probability limit) daily net community production of 71.3 +/- 58.6 mmol C m(-2) d(-1). Conversely, net community production was always negative in intertidal regions and subtidal bare sediments (average -7.3 +/- 46.7 mmol C m(-2) d(-1) and -47.0 +/- 38.9 mmol C m(-2) d(-1), respectively); the C. nodosa bed was negative in November (-96.2 +/- 85.1 mmol C m(-2) d(-1)) and positive in January (33.4 +/- 82.6 mmol C m(-2) d(-1)). Community respiration was highest in subtidal communities, indicating active mineralization of organic matter and demonstrating that Z. noltii beds are likely to increase the bio logical richness of the Banc d'Arguin by exporting energy. Our results confirm the ecological importance of seagrass beds in the net coastal carbon fluxes and justify their protection.
Marine Ecology Progress Series (0171-8630) (Inter-research), 2014 , Vol. 501 , P. 11-23

Droits : Inter-Research 2014 · www.int-res.com
http://archimer.ifremer.fr/doc/00189/29987/28496.pdf
DOI:10.3354/meps10683
http://archimer.ifremer.fr/doc/00189/29987/