Plunging into the Great African Seaforest: How does kelp impact us?
(Header image credit: Albert Snyman)
South Africa’s west coast is home to one of the most incredible kelp forest systems in the world: The Great African Seaforest. While roughly 25% of our blue planet is covered with kelp forests, many of these have experienced drastic declines over recent years as the ocean warms. Our Great African Seaforest is one of the few that have not wilted in the face of climate change – with this in mind, is it not crucial that its stewards appreciate its value and know how best to conserve it for future generations?
Plunging into the Great African Seaforest
Immersing oneself in a kelp forest is an experience like no other. At the surface, sunlight filters through the fronds and creates the sensation of being suspended above a vast and mysterious world. Dive deeper, and that world awakens, filling one’s eyeline with colour and life. Flip around, look up, and you’re lying on the seaforest’s floor as red stumpnose soar through the kelp and klipfish dart alongside vibrant anemones.
In the Great African Seaforest, two dominant kelp species form the forest’s canopy: Sea bamboo (Ecklonia maxima), topped with a gas-filled bulb that lets the fronds float, and split-fan kelp (Laminaria pallida).
These species are the pillars around which the kelp forest ecosystem thrives. In fact, many consider kelp forests to be the cold-water equivalent of coral reefs – they support abundant biodiversity, aid in species regeneration, and play a huge role in carbon sequestration.
Kelp forests as havens for biodiversity
Submerged in the heart of a kelp forest, it is easy to imagine it as a metropolis of marine life. Over millions of years, kelp forests have evolved to split into three distinct stories, with the structure of the kelp itself as a guide.
At the top, the blades (or fronds) absorb sunlight and nutrients. The stipe (the length of the kelp) is anchored to the ocean floor by a holdfast that grips the rocks amidst the fiercest wave surges. Each point represents a home base or foraging ground for hundreds of species – the fronds shelter fish such as white steenbras and galjoen, the stipe is home to limpets, abalone, and crabs, and nestled near the holdfast are urchins and chitons. The forest provides shade, shelter from wave action, and shelter.
Of course, kelp is a food source for many forms of marine life, too. The tips of the kelp fronds constantly erode, so the resultant particulate matter entering the water is food for filter feeders like mussels, sponges, and red bait. Predatory species such as Cape fur seals, octopuses, seabirds, sharks, and even Cape clawless otters forage and hunt in the Great African Seaforest.
Upwelling, a phenomenon typical of the cold waters on the western coast of South Africa, plays a significant role in creating thriving kelp forest ecosystems such as these. The southeasterly winds that buffet the Cape Peninsula in summer cause rich nutrients from the cold, dark depths of the ocean to rise. These nutrients fertilise the kelp and provide food for filter-feeding species.
As with so many marine ecosystems, this delicate balance is all utterly dependent on the thriving of each element. When sea urchins are not adequately preyed on, they can decimate a kelp forest. Without their food supply of kelp detritus, filter feeders like sponges would fall away, and the ecosystem would slowly fall apart. In a nutshell, kelp forests are one of the most highly productive and valuable ecosystems in the world.
Kelp forests as carbon sinks
It is a well-known fact that the ocean acts as an enormous carbon sink, but did you know that kelp forests can take credit for a significant chunk of that?
Research shows that the carbon captured by kelp forests is comparable to the combined impact of mangroves, salt marshes, and seagrass meadows. By pulling carbon dioxide out of the water, kelp doesn’t just store carbon – it also acts as a buffer against ocean acidification. Kelp actively absorbs carbon dioxide, raising the pH levels of the surrounding water and helping species like shellfish and coral build the shells and skeletons they need to thrive.
When kelp takes up inorganic carbon, it transforms it into organic biomass, a vital part of the carbon cycle. Some of this breaks off, drifting away with ocean currents, where it’s eventually consumed, decomposed, or sequestered. To put this into perspective, in the eastern Canadian Arctic, extensive kelp forests have been estimated to store the carbon equivalent of the annual greenhouse gas emissions of more than five million people.
Globally, climate change has placed kelp forests under pressure. However, our Great African Seaforest appears to have a different story. Our kelp forests are actually expanding, likely thanks to the influence of upwelling and the steady cycle of nutrients.
Kelp forests as protectors of our coastline and our marine life
Anyone who has spent time in a kelp forest is familiar with the feeling of fronds curling around fins or limbs. This density, besides being a home to wonderful marine life, serves another purpose: Protecting our coastline.
Kelp forests act as a dampener for the effect of rough waves and storm surges, mitigating coastal erosion. It has even been shown that kelp forests can reduce wave sizes by up to 60% as they create a protective layer within the water that breaks down the current. So, on those blustery Western Cape days, we can be grateful for the kelp forests that buffet us against the waves!
Denser kelp forests also provide calm “microhabitats” for our marine life. The more peaceful waters amongst the kelp protect marine species at multiple levels of the food web from unfavourable ocean conditions.
What is our relationship with kelp?
It may be surprising how often kelp is used in our day-to-day lives. Algin, an emulsifying and bonding agent, is extracted from kelp and used to make toothpaste, shampoo, salad dressings, dairy products, and even pharmaceuticals.
In South Africa, though, kelp plays its biggest role in the abalone farming and fisheries industries, with the estimated annual value of kelp ecosystems at around US$434 million. That figure reflects not just kelp-dependent fisheries, but also ecotourism, coastal protection, and carbon storage.
Commercial kelp harvesting began in the 1980s, mainly for agricultural biostimulants, and expanded in the late 1990s as the demand for abalone grew. Before then, kelp was mostly collected after washing ashore. Today, both fresh fronds and beach-cast kelp are harvested in 23 of South Africa’s regulated concession areas. According to government reports, harvests have remained relatively stable (just over 5 000 tonnes annually in recent years), and the resource is considered to be optimally managed.
In a recent study, it was revealed that South Africans know kelp to be vital to the health of our coasts and ocean. Nearly 90% of respondents valued the role of kelp forests in maintaining healthy marine and coastal environments, while over 80% appreciate the habitats it creates for abalone, rock lobster, and countless other species. The regulating contributions of kelp forests (their ability to stabilise, protect, and sustain) stood out most strongly. One Cape Town respondent put it plainly: Kelp forests help trap sand and raise beach profiles, offering a natural defence against coastal erosion. In a city where urban development borders the shoreline, that service is invaluable.
While the economic value of kelp is well documented, its sociocultural value is perhaps less so. The role of kelp in our South African heritage and identity is not as thoroughly studied. Local foragers and knowledge-holders recall that kelp was historically used by Indigenous coastal communities for subsistence. Unfortunately, little academic research has been done to record these practices, and today, kelp is hardly used as a food source in South Africa. This is certainly an area of interest that deserves further exploration.
It is clear that the relationship South Africans have with kelp is many-layered. Beyond its ecological role, kelp is also recognised for its material contributions, such as supporting fisheries, livelihoods, and local economies. Together, these insights reflect both the intrinsic worth of kelp and its practical importance in keeping people and coastal ecosystems resilient.
What are the threats to kelp forests?
Kelp forests may be resilient, but they’re not invincible. There are multiple culprits to their decline: Warming oceans, overgrazing by sea urchins, pollution from land run-off, sedimentation, overharvesting, invasive species, and disease. Often, these threats stack up, leaving kelp increasingly vulnerable in a changing climate.
Around the world, commercial and industrial overfishing has decimated important marine species, weakening ecosystems and reducing biodiversity. Overfishing has depleted species that would normally keep sea urchin populations in check. With fewer natural predators, sea urchins can overgraze and devastate kelp forests.
Closer to home, poaching in South African kelp forests has caused a rapid decline in rock lobster and abalone populations, species that play vital roles in keeping these ecosystems balanced.
Rising sea temperatures are one of the biggest concerns. Warmer waters can weaken kelp at the cellular level, making it less resilient to wave forces and reducing its overall strength. Chemical waste and pollution along the Western Cape coastline further threaten marine life.
Kelp forests provide exactly the benefits humans need most: They shelter commercially valuable seafood species, protect biodiversity, and support jobs and local economies. Yet, in just the past 50 years, climate change, poor water quality, and overfishing have already damaged between 40% and 60% of the world’s kelp forests. The stakes couldn’t be higher for these underwater strongholds.
How can we conserve kelp?
Conserving kelp for future generations goes hand-in-hand with working against the effects of climate change.
Conservation and restoration efforts need to combine community involvement, long-term financial support, and consistent monitoring. The most effective strategies take an ecosystem-based approach, which implements several approaches to address individual pressures to kelp forests, such as marine spatial planning, Marine Protected Areas, improving coastal water quality, and sustainable management methods.
Considering that the data around kelp forests is relatively sparse, supporting a network of global kelp observations and knowledge sharing would be hugely conducive to their conservation.
At its core, conserving kelp is about more than saving seaweed. Rather, it centres around safeguarding entire ecosystems, local economies, and the resilience of our coasts in the face of climate change.
From providing home bases for an incredibly wide range of marine organisms to contributing to the livelihoods of thousands of South Africans, kelp is of central importance to our planet and its people. There is no denying the value kelp forests hold, both as an economic resource and an ecological powerhouse. These magical seaforests are the beating heart of South Africa’s west coast, and are worth protecting for future generations to experience their wonder.
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