eNews

#02 2025

SAEON Egagasini Node leads collaborative deep-sea exploration in African waters onboard the OceanXplorer

By Jordan Van Stavel & Lara Atkinson, Egagasini Node and SAPRI, NRF-SAEON

The Around Africa Expedition, led by global ocean exploration non-profit organisations OceanX and the newly established OceanQuest, is a pioneering collaborative expedition along the African coastline and an endorsed action programme of the United Nations Ocean Decade framework (2021–2030). The initiative aims to contribute to capacity building and scientific understanding of the ocean, marking a pivotal moment in ocean exploration and scientific research.

The first part of the expedition, Science Leg 1, began on January 30 in Moroni, Comoros, and was conducted aboard OceanX’s state-of-the-art research and media vessel, OceanXplorer.

The OceanXplorer sailing through the Indian Ocean during the first science leg. (Image: OceanX)

The route of the Around Africa Expedition, an endorsed action programme of the United Nations Ocean Decade framework. (Map: OceanQuest)

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.

The guest science team and members of the OceanX team onboard. (Image: OceanX)

The OceanXplorer houses two Triton submersibles on board – Neptune and Nadir. The photo shows Neptune and Nadir on the water surface during the expedition. (Photo: OceanX)

Submersible dive experience 

A good weather window experienced during the expedition enabled three submersible dives to be conducted, each exploring different aspects of Walters Shoal seamount and allowing nine members of the visiting science team to share in this experience.

Dr Lara Atkinson and Jordan Van Stavel (South African Polar Research Infrastructure) each had the incredible opportunity to participate in a submersible dive, exploring this remarkable deep-sea landscape firsthand. The submersibles descended to a depth of approximately 500 m at the base of the seamount. The seamount was mostly populated with soft and hard corals, sponges and brisingid sea stars, with enchanting fish at shallower depths.

Jordan described the submersible dive as one of the most awe-inspiring and ethereal experiences of her career and her life. “It has reignited my passion for the work we do, reminding me of its profound significance. Witnessing marine life in their natural habitat was nothing short of unforgettable,” she said.

Dr Lara Atkinson described the experience as follows: “Descending 500 metres into the deep and seeing the seafloor unfold before my eyes was surreal – like exploring the equivalent of an underwater fynbos landscape of the Western Cape, but underwater. Here everything moves slower – it was incredibly calm and peaceful. Watching a large octopus ‘play catch’ with the submersible’s lasers was a fascinating display of intelligence and something I will never forget.”

Other members of the science team who had their first ever opportunity of experiencing a dive in the submersibles during this expedition include Bibiana Nassangole (Mozambique), Jovial Mbony (Madagascar), Dr Njaka Masimana (Madagascar), Sinothando Shibe (South Africa), Amina Makori (Kenya) and Thabo Mbuyazi (South Africa).

Jordan Van Stavel (left) and Dr Lara Atkinson in the mission control room onboard the OceanXplorer. (Image: Mario Tadinac)

Dr Lara Atkinson and Sinothando Shibe (from South African National Parks) in the submersible Neptune just prior to deployment at Walter Shoal seamount. (Photo: OceanX)

Overall, the opportunity that the OceanX–OceanQuest Around Africa Expedition presented to many South Africans and marine researchers from five additional African countries, was a remarkable and rewarding experience and is certain to have forged long-lasting collaborations and friendships.

Jordan Van Stavel and Amina Makori (Kenyan Marine Fisheries Research Institute) submerged in the water column inside Neptune during the third submersible dive. (Photo: OceanX)

The first submersible dive on this leg of the expedition, at the base of Walters Shoal seamount. Inside the submersible were scientists Bibiana Nassongole (Lúrio University, Mozambique), Dr Masimana Gaidi Marenjaka (University of Toliara, Madagascar) and the OceanXplorer submersible pilot, Colin Wade. The team were exploring the seamount and preparing to collect samples. (Photos: OceanX Media team)