The first science leg of the Around Africa Expedition, conducted in collaboration with NRF-SAEON, was co-led by Dr Lara Atkinson from the SAEON Egagasini Node. The guest science team onboard included 18 established and early-career researchers from South Africa, Madagascar, Mozambique, Kenya, Tanzania, Comoros, Portugal, Brazil, Germany and Saudi Arabia.

This first science leg aimed to conduct seabed mapping and visual biodiversity surveys of Indian Ocean seamounts on the Madagascan Ridge and Agulhas Plateau. Quantifying both the physical features and the biodiversity at these seamounts will advance scientific knowledge, helping to guide informed decisions on conservation and restoration efforts in these remote ocean areas. Although these seamounts are in the high seas, far from any human populations, their contribution towards serving as larval transport corridors may be important and could influence population connectivity across vast ocean distances, supporting ecosystem resilience and replenishment of fisheries in both deep-sea and coastal environments.

The objectives of this expedition were to 1) map the geological characteristics of three seamounts surveyed, 2) document the invertebrate and fish biodiversity observed, 3) conduct environmental DNA metabarcoding of sampled sponges and water, and 4) collect environmental parameter information from filtered water samples such as temperature, oxygen, salinity, nutrients, plankton and microbes.  These objectives were met, with more than 33 000 km2 of seabed area being mapped in high resolution, including three seamounts, two of which had never been mapped before.

At the Walters Shoal seamount, four seabed survey transects were completed using the remotely operated vehicle (ROV), surveying from 500-m to 150-m depths on four aspects of the seamount. A further ROV survey was completed from 2 000 m to 1 600 m along one aspect of an unnamed seamount south-east of Walters Shoal on the Madagascan Ridge. During these transects, approximately 35 hours of footage has been recorded and a total of 209 specimens collected for taxonomic validation or description and genetic sequencing. Rock and sediment samples were also collected, where possible, to assist in describing the geology of these features.

A total of 54 seawater samples were filtered for eDNA processing, while 46 sponge samples were sub-sampled for eDNA. With soft corals being the dominant group observed at Walters Shoal, a total of 32 samples were collected. Preliminary identification indicates they belong to eight families. The enormous amount of footage and samples collected during this expedition will keep the researchers busy for months to come, making this expedition a huge success.