Éditeur(s) : Amer Soc Limnology Oceanography
Résumé : A new benthic station equipped with oxygen microelectrodes and environmental sensors was developed by Laboratoire des Sciences du Climat et de L’Environnement (LSCE) and Division Technique of the Institut National des Sciences de L’Univers (DT-INSU) to perform in situ time series monitoring of sediment oxygen demand, linked to the mineralization of organic matter. The time series typically cover periods of 2-3 months, with a base frequency of 1 set of oxygen profiles per day. The profiling head assessed the lateral heterogeneity of the sediment oxygen demand at the beginning of the time series over a 0.8-m long rectangle to discriminate spatial and temporal variability. A continuous recalibration is performed using a moored oxygen optode anchored to the benthic station together with a set of environmental sensors. These sensors (turbidity, temperature, salinity, and oxygen) can trigger a high-frequency profiling mode to investigate the fate of particulate organic matter delivered during floods, resuspension, and deposition events. Deployments of the benthic station were performed in the Rhone River subaqueous delta (Mediterranean Sea). We show that “stable” periods (when neither floods nor storms occur) were characterized by a stable oxygen demand. In the case of resuspension events, an increase of the sediment oxygen demand by a factor of 2-3 with a relaxation time of 1 day was observed, indicating that the new benthic station can adequately capture the impact of resuspension events on the oxygen demand in deltaic sediments.
Limnology And Oceanography-methods (1541-5856) (Amer Soc Limnology Oceanography), 2014-11 , Vol. 12 , P. 729-741

Droits : 2014, by the American Society of Limnology and Oceanography, Inc.
http://archimer.ifremer.fr/doc/00230/34126/32597.pdf
http://archimer.ifremer.fr/doc/00230/34126/36349.pdf
DOI:10.4319/lom.2014.12.729
http://archimer.ifremer.fr/doc/00230/34126/

Éditeur(s) : Pêche thonière et dispositifs de concentration de poissons, Caribbean-Martinique, 15-19 Oct 1999 15-19 octobre 1999
Résumé : Since 1983, the research on the optimal conception of FADs in Martinique was particularly focused on the improvement of their resistance to different maritime or human aggressions. Following several experimentations made with different types of fads, the choice was brought on light devices anchored in 1 500 to 2 000 m depths and an experimental approach was conducted to identify the causes of loss of fads and to attempt to modelize their hydrodynamic behaviour with relation to the sea conditions. Three mathematical models are used to simulate the fad behaviour under current action and swell, and to estimate the forces exerted on each part of the device. The results of this study are presented. The fad design used nowadays for the development of pelagic fishing in Martinique, recommendations for maintenance and preservation of the fads are also proposed.Original Abstract: De 1983 a 1994, les recherches sur une conception optimale des DCP de la Martinique ont ete plus particulierement orientees sur l'amelioration de leur resistance aux diverses agressions marines ou humaines. Suite aux multiples experimentations menees avec differents types de DCP, le choix de systemes legers ancres par fonds de 1 500 a 2 000 m a conduit a une demarche scientifique comprenant a la fois une analyse des causes de perte des DCP et la modelisation de leur comportement hydrodynamique en fonction des conditions de mer. Les resultats de ce programme ainsi que le plan du DCP retenu pour le developpement de la peche des poissons pelagiques en Martinique sont presentes. Des recommandations pour la maintenance et la preservation des dispositifs sont egalement proposees.

Droits : Ifremer
http://archimer.ifremer.fr/doc/00042/15287/12673.pdf
http://archimer.ifremer.fr/doc/00042/15287/