Denis, L. Université de la Méditerranée, Ldenis@com.univ-mrs.fr
Grenz, C. Université de la Méditerranée, grenz@com.univ-mrs.fr

 
OXYGEN AND NUTRIENT FLUXES FROM SHELF SEDIMENTS IN THE GULF OF LIONS (NW MEDITERRANEAN SEA)
 
Benthic flux measurements were performed during two successive cruises in March and June 1998 at nine, 60 to 170 m deep stations located on the continental shelf in the Gulf of Lions. Two stations were selected for a monthly survey during 1998: station R near the Rhone River mouth and station S located near the continental shelf edge, rarely influenced by inputs of organic matter and nutrients from the continent. Fluxes of oxygen, dissolved silicate, dissolved inorganic nitrogen and phosphate were measured using onboard incubation technique. Data showed spatial variations related to organic matter gradient in the sediments, with highest fluxes measured at R station. Accordingly temporal fluctuations showed higher fluxes for this station (385±46 up to 707±85 µmolO2.m-2.h-1). Temporal variations at S station showed maximum sediment oxygen demand and silicate fluxes towards the water column (213±59 up to 538±127 µmolO2.m-2.h-1 and 10±2 up to 30±8 µmolSi.m-2.h-1 respectively) during summer and could be related to the sedimentation of a late spring phytoplankton bloom. These temporal and spatial flux measurements combined with macrofaunal distributions and vertical sedimentation rates of organic matter measured in parallel at a close station are discussed in the context of an annual budget of oxygen and nutrients for the Gulf of Lions.
 
Day: Friday, Feb. 5
Time: 09:15 - 09:30am
Location: Sweeney Center
 
Code: CS63FR0915S