iSimangaliso Wetland Park, renowned for its exceptional biodiversity and eco-tourism activities, has recently surprised the scientific community with an extraordinary kelp discovery that shines a light on South Africa’s hidden marine treasures.
During an exploratory survey aboard WILDTRUST research vessel, the Angra Pequena, there has been an unearthing of South Africa’s hidden underwater forests of vital ecological importance within the Park’s mesophotic zone; the region of the ocean where sunlight barely penetrates.
During the latest research survey aboard the vessel to study the kelp forest characteristics, a research team uncovered expansive fields of rhodoliths – free-living, calcareous red algae that resemble pink-hued nodules scattered across the seafloor. These seemingly unassuming formations play an outsized role in marine ecosystems. Rhodolith beds are recognised globally as biodiversity hotspots, comparable to coral reefs and seagrass meadows. They provide refuge and nursery habitats for countless marine species, from invertebrates to juvenile fish. Their complex, three-dimensional structures stabilise sediments, enhance habitat diversity, and serve as vital kelp and other macroalgae substrates. While the presence of rhodoliths in the greater iSimangaliso area have been suspected previously, their extent and complex relationship with the kelp bed represent an extraordinary discovery.
The research team was led by Dr Welly Qwabe and Prof Lucy Woodall, from Ezemvelo KZN Wildlife and the University of Exeter (UK) and Nekton, respectively, along with Dr Vivienne Coetzee, a postdoctoral fellow at the University of Cape Town working under the WILDOCEANS programme.
This incredible discovery was made possible through support and funding from the National Research Foundation (NRF), Blue Action Fund, the National Department of Forestry, Fisheries and the Environment, Nekton, the South African Environmental Observation Network (SAEON) and Oceans 5, as well as several other local and global partners and collaborators.
A Rare Ecological Gem
This marks only the second rhodolith bed ever documented in South African waters, the first being discovered off the Kei River in the Eastern Cape. This discovery is an unprecedented ecological milestone for KwaZulu-Natal and the extra-special iSimangaliso Wetland Park, a World Heritage Site. The rhodolith beds were found alongside a dense forest of Ecklonia radiata (golden kelp), stretching 35 kilometres along the seafloor.
“Together, these ecosystems form an intricate partnership,” said 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.”
A Call for Conservation
“Rhodolith beds are fragile and exceedingly slow growing, often taking centuries to recover from disturbance. Threats such as bottom trawling, pollution, and ocean acidification place these critical habitats at risk,” said Woodall. “The discovery within iSimangaliso Wetland Park highlights the urgent need to safeguard not just the ecosystems we readily see, but also the hidden seascapes that lie beneath the ocean’s surface.”
“This discovery reminds us of how much there still is to uncover beneath the waves,” said 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.”
“By depth, iSimangaliso MPA encompasses unique and diverse marine ecosystems characteristic of the east coast of South Africa,” said Riaan Cedras, Ecologist at iSimangaliso Wetland Park Authority. “The findings of this study slowly uncover those things of the deep. Coral reefs. Kelp beds. The plankton and the fish that feed us. Research on species and ecosystems by partners in this World Heritage Site encourages iSimangaliso and emphasises that research is needed in this field.”
As WILDTRUST and research partners continue to uncover and map these twilight treasures, the call for expanded marine protections grows stronger. The safeguarding of these ecosystems will ensure they continue to provide invaluable services for generations to come.