30 November 2022

Note of 30 November 2022

Francis Marsac, IRD representative in the Seychelles, fisherman and oceanographer, was the coordinator of the various scientific projects on the Saya de Malha Bank during the Monaco Explorations’ Indian Ocean mission. Three intense weeks and a lot of satisfaction on the spot, including on a human level, with great extensions and results in prospect.

The campaign comes to an end

The Saya de Malha Bank is already far behind the wake of the S.A Agulhas II… The campaign ended in Mauritius on 22 November, with the laboratories emptied of the equipment especially brought for this project. Measuring instruments, fishing gear, and collected specimens were put back in the container and in crates that will be unloaded in Cape Town, the final destination of the Monaco Explorations journey that started on 3 October, before being sent to the French laboratories. Great silence on board after the past agitation on the deck, the noise of the winches, the comings and goings of one or the other, the doors opening and closing… The hive is deserted, end of campaign’s wistfulness!

What will remain after our passage on this shallow sea in the middle of the ocean? Barely a few traces of our dragging gear, which will soon be blurred by the currents that relentlessly reshape the sediments. On the other hand, a magnificent harvest of specimens of benthic communities, collected over barely 60,000 m² divided into five sectors, along a 1600 nautical mile route on the Saya de Malha bank.

What exactly are we talking about? 300 to 400 species of molluscs, around 300 species of crustaceans and a hundred or so species of algae were brought on board, sorted, and examined under a binocular magnifying glass by our experts from the National Museum of Natural History. Already, three gastropod specimens and one crustacean are considered new species, i.e. not yet described by taxonomists.

Two emblematic species, a gastropod, Conus primus, and the giant clam Tridacna rosewaterii, were ‘re-discovered’ on Saya de Malha. “The potential for discovery of other endemic and even new species among our collections is significant,” says Professor Philippe Bouchet, an internationally renowned malacologist and member of the expedition. This will keep specialists busy for the next five years, given the scale of this harvest. To be followed very closely!

Gigabytes of digital data on physico-chemical and biological parameters measured by the CTD probe in the water column have been stored on the computers. There are also long hours of video footage filmed by the ROV during its seven dives, and images taken by various cameras anchored to the seabed that remain to be processed, enough to provide research topics for our young researchers in the region. This choice information on the properties of the water column and the habitats visited gives context to the floristic and faunistic inventory described above.

We can be satisfied with this initial scientific assessment. However, the first asset of the expedition lies in the human aspect. The scientific team was made up of scientists from Seychelles (including students), Mauritius, France, South Africa, and Spain. A melting pot of nationalities and skills that worked wonderfully. An inter-generational fusion of exchanges, interaction, mutual aid, and interests that took place after only a few days of learning from each other.

In my opinion, the Monaco Explorations expedition has greatly contributed to strengthening exchanges between Seychellois and Mauritian scientists. They did not know each other very well, but now they have a strong motivation to develop joint projects. “When to for the next campaign?” they exclaimed as they left the ship. The framework of the Saya de Malha Joint Management Area is a perfect fit, as Seychelles and Mauritius have each developed a Blue Economy roadmap and want to work together towards the sustainable use of Saya de Malha resources. This can only be done on a scientific basis. I am convinced that this desire to work together is not a “one shot”. It will continue in a broader framework, including training and future projects to be co-designed with the expedition’s scientists from outside the region.


Francis Marsac

Administrator Representative of IRD in the Seychelles, Halieute and oceanographer, coordinator of the scientific operations carried out on Saya de Malha during the second part of the Monaco Explorations’ Indian Ocean mission.

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