Summary of Abstract Submission

Abstract Submission No. IO50-04-0045PresentationPoster


TERNON Jean-François*1, ROBERTS Michael J.2, MARSAC Francis1, SAMAAI Toufiek2, HUGGETT Jenny2, LAMONT Tarron2, BOUCHET Philippe3

1 Institut de Recherche pour le Développement, France
2 Department of Environmental Affairs, South Africa
3 Museum National D'Histoire Naturelle, France


Interactions between the ocean circulation and topographic features such as sea-mounts generate physical processes that can be important drivers for the benthic and pelagic ecosystems. Upwelling on sea-mount slopes are examples of such biologically important processes that make the study of sea-mount ecosystems relevant to the goals of the WIOURI (Western Indian Ocean Upwelling Research Initiative) of the IIOE-2. MADRIDGE is one of the nine sub-projects of WIOURI. Using case studies, it focuses on two different sea-mounts on the longitudinally aligned South Madagascar Ridge ─ the isolated Walter Shoal (33°S) with a shallow summit depth of 20 m and an unnamed sea-mount located just south of Madagascar (27° 30'S) with a deeper summit depth of 200 m. The two sites experience different oceanographic environments with the Walter Shoal being located at the southern boundary of the South Indian Subtropical Gyre, within a low mesoscale turbulence area. In contrast, the unnamed sea-mount close to Madagascar is located within a mesoscale eddy corridor and the retroflection extension of the fast flowing East Madagascar Current. Observed fishing activity and the presence of seabird foraging at the two sea-mounts are strong indications of enhanced biological production. A third sea-mount located west of La Réunion Island will be investigated for comparison with the Madagascar Ridge sea-mounts. Four cruises sponsored by France and South Africa have been planned to undertake sampling of the oceanographic and biological environments surrounding these sea-mounts and will be presented together with some preliminary results from the first one completed in 2014.