iSimangaliso Wetland Park, a UNESCO World Heritage Site and one of South Africa’s most celebrated eco-tourism destinations, has revealed an extraordinary underwater discovery. Recent marine research uncovered vast rhodolith beds and thriving kelp forests in the Park’s mesophotic zone—an area of the ocean where light barely reaches, yet life flourishes in remarkable ways.
A Groundbreaking Discovery Beneath the Waves
The discovery was made during an exploratory survey aboard Angra Pequena, a WILDTRUST research vessel. Led by Dr. Welly Qwabe (Ezemvelo KZN Wildlife), Prof. Lucy Woodall (University of Exeter and Nekton), and Dr. Vivienne Coetzee (University of Cape Town, WILDOCEANS programme), the team uncovered extensive rhodolith fields—free-living red algae that form pink, rock-like nodules across the seafloor.
Though seemingly unassuming, these formations are ecological powerhouses. Globally recognized as biodiversity hotspots, rhodolith beds rival coral reefs and seagrass meadows in importance, providing:
- Shelter and nursery grounds for invertebrates and fish
- Stable substrates for kelp and macroalgae growth
- Enhanced habitat complexity, essential for marine biodiversity
While their existence in the broader iSimangaliso region had long been suspected, this is the first time such expansive and ecologically intertwined rhodolith and kelp systems have been documented here.
South Africa’s Rare Rhodolith Bed
This is only the second recorded rhodolith bed in South African waters, following the first discovery near the Kei River in the Eastern Cape. In iSimangaliso, researchers found them alongside a dense 35-kilometre-long golden kelp forest (Ecklonia radiata).
“These ecosystems form an intricate partnership,” explains Dr. Coetzee, who will lead further studies. “Rhodoliths provide hard surfaces for kelp to anchor, while kelp forests shape conditions such as light and nutrients. Together, they boost carbon sequestration and provide vital nurseries for commercially valuable fish species.”
The Urgency of Marine Conservation
Despite their importance, rhodolith beds are fragile and extremely slow to recover, often taking centuries after disturbance. Bottom trawling, ocean acidification, and pollution pose major threats.
“The discovery within iSimangaliso highlights the urgent need to protect not only visible marine life but also the hidden seascapes beneath,” says Prof. Woodall.
Dr. Jean Harris, WILDTRUST Strategic Ocean Lead, echoes this:
“South Africa’s mesophotic habitats are biodiversity reservoirs. Protecting them is critical for climate resilience and sustainable blue economy opportunities.”
Protecting a World Heritage Jewel
Riaan Cedras, Ecologist at iSimangaliso Wetland Park Authority, emphasises the significance:
“By depth, iSimangaliso Marine Protected Area encompasses ecosystems unique to South Africa’s east coast. Coral reefs, kelp beds, plankton, and fish all depend on research and protection. These findings strengthen the case for continued conservation.”
Looking Ahead
This milestone was made possible through support from the National Research Foundation (NRF), Blue Action Fund, Department of Forestry, Fisheries and the Environment, South African Environmental Observation Network (SAEON), Oceans 5, and global collaborators.
As WILDTRUST and partners expand research, the call grows stronger for enhanced marine protection. Safeguarding iSimangaliso’s underwater forests and rhodolith beds ensures these ecosystems continue to sustain biodiversity, climate resilience, and local livelihoods for generations to come.
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