The discovery of an ecologically important ‘secret of the sea’ has stirred some excitement off the coast of KZN!
iSimangaliso Wetland Park, South Africa (15 August 2025) – A team of scientists on board the Angra Prequena research vessel off the coast of iSimangaliso Wetland Park in KwaZulu-Natal have discovered a rare habitat in the ocean’s ‘twilight zone’.
While studying the park’s deep kelp beds, the crew discovered an expansive bed of rhodoliths. A rare find in South Africa!
Rhodoliths are a pebble-like, calcareous red algae. They look like pink stones scattered across the seafloor, but they play a critical role in the ocean.
These beds create safe spaces for young fish and invertebrates, help stabilise the sea floor, and support healthy kelp forests. Globally, they’re recognised as biodiversity hotspots, but are rare in SA waters.
In fact, this is only the second official rhodolith bed found in South Africa, ever. The first was discovered off the Kei River in the Eastern Cape.
The new discovery was made during a survey led by Dr Welly Qwabe and Prof Lucy Woodall, working with Ezemvelo KZN Wildlife, the University of Exeter, Nekton, and other research partners.
The newly-mapped area lies alongside a 35-kilometre stretch of golden kelp in the ‘mesophotic zone’, where sunlight just barely reaches.
“Together, these ecosystems form an intricate partnership,” says Dr Vivienne Coetzee, a post-doc who will be leading a further study on these new extensive rhodolith areas.
“Rhodoliths provide hard surfaces essential for kelp attachment, while kelp forests create canopy habitats that modify light, nutrient levels, and water movement. Their interconnected roles support carbon sequestration and offer crucial nursery grounds for commercially valuable fish species, essential for biodiversity conservation and sustainable fisheries.”
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The discovery is good news for marine conservation, but also a reminder to tread very carefully.
Rhodolith beds grow slowly and can take centuries to recover from damage. They’re sensitive to threats like trawling, pollution, and ocean acidification.
“This discovery reminds us of how much there still is to uncover beneath the waves,” says WILDTRUST Strategic Ocean Lead and Captain of the Angra Pequena, Dr Jean Harris.
“South Africa’s mesophotic habitats are essential biodiversity reservoirs, playing a key role in climate resilience and future blue economy opportunities.”
As WILDTRUST and their research partners keep exploring these secret pockets of ocean life, the need to protect them gets even louder. By looking after and protecting these rare habitats now, we’re making sure the ocean can keep doing its job.
Sources: Supplied
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