01-05 December 2025
INCOIS, Hyderabad, India.
| Abstract Submission No. | ABS-04-0098 |
| Title of Abstract | Observations of surface currents and inter-connectivity in the Indian Ocean west of Mascarene Plateau: an IIOE-2 (Project IIOE2-EP49) / Monaco Explorations Indian Ocean Expedition collaboration |
| Authors | Nick D'Adamo*, Charitha Pattiaratchi, Jean-Francois Ternon, Patrick Vianello, Priscilla Coopen, Tessa Hempson, Heather Koldewey, Arshad Rawat, Mike Roberts, Chris Simpson |
| Organisation | University of Western Australia |
| Address | 70 JONES ST STIRLING, WA, Australia Pincode: 6021 E-mail: nick.dadamo@uwa.edu.au |
| Country | Australia |
| Presentation | Oral |
| Abstract | Connectivity in the SW Indian Ocean was studied by tracking 18 sea surface drifters (SSD) and 4 SVP drifters during the 2022 Monaco Explorations Indian Ocean Expedition (ME-IOE), endorsed as IIOE2-EP49. The SSD types used originate from the University of Western Australia and have also been deployed in the NW IO. They add to traditional drifter techniques (e.g. SVPs which track currents at 15 m depth) as cost effective and easy to deploy trackers of currents in the upper ~50 cm. Deployments ran from Mauritius to Aldabra Atoll to Seychelles and then along Mascarene Plateau back to Mauritius, comprising a cluster west of Aldabra Atoll, a set around Saya de Malha Bank, and others at various locations along the circuit. Circulation features observed included the South Equatorial Current (SEC), South Equatorial Countercurrent, East African Coastal Current, Northeast Madagascar Current, Southeast Madagascar Current, eastward retroflexions, Indian Ocean Countercurrent and mesoscale eddies in the Mozambique Channel. On passing over Mascarene Plateau, the SEC characteristically diverged laterally into north-westward, westward and south-westward offshoot cores, with these further diverging on approaching coasts. Tracks of up to 9000 km / 10 months were observed. Connectivity ranged from weeks to a few months between high biodiversity areas such as the Mascarene Plateau, East African coastal zone and islands and atolls between. Westward movements between Aldabra and east Africa (Tanzanian coast) were found to be < 4 weeks, at mean speeds of ~ 0.3-0.5 ms-1 with maximum speeds ~1.3 ms-1. This work complements other connectivity studies of the region, providing insights on the potential for biological propagule transport and ecological connectivity between potential source and recruitment zones, and on transport potential for anthropogenically derived materials such as debris (e.g. plastics) and toxicants (e.g. oil). These insights are relevant to biodiversity conservation, environmental and natural resource management interests. |
| Are you part of IIOE-2 endorsed project | yes |
| Endorsed Project Number | IIOE2-EP49 |
| Keywords | Northwest Indian Ocean, biological and physical connectivity, surface currents, satellite tracked sea surface drifters, Monaco Explorations Indian Ocean Expedition |
| For Awards | no |