Kelp Forests of South Africa
South Africa has one of the biggest kelp forests in the world. Kelp is a marine algae and not a true plant and species range from shorter growing “bottom kelp” to much taller species. This ecosystem serves as food and shelter for many marine species and is one of the richest habitats on earth. The canopy of these forests can be seen from the shore on the surface of the water and looks like a shiny green mass but once you go below the surface an enchanting new world opens up.
In the beginning, when I just started entering kelp forests as a snorkeler and later a new Open Water scuba diver, the kelp felt like a scary dark place that would entangle me. But soon you learn that if you just go with the back and forth sway of the surge the kelp opens up and becomes a serene place with the slippery leaves lightly flowing over your body with the movement of the water. If you slow your breathing and listen, you can hear the crackling of the kelp and when you look up, you see a mesmerizing scene of sun rays trickling down through the tall trees. A whole new world to explore and get lost in.
The importance of kelp forests
These forests are incredibly important as they help preserve the health of the oceans through their fast-growing rate and photosynthesis. They purify the water since kelp thrives on waste products produced by its inhabitants. Kelp forests play a key role in combating the effects of climate change, like other highly productive ecosystems such as mangroves and rain forests, kelp forests can absorb and hold carbon which might otherwise end up contributing to rising global temperatures. This is called carbon sequestration, and efforts to restore and enhance kelp and seagrass beds to store more “blue carbon” are increasingly seen as a tool to help counter the effects of a warming ocean and world. Kelp also helps reduce coastal erosion serving as a buffer for storm-driven waves and surges.
Distribution and recent spread
South Africa’s swaying underwater forest extends for about 1 000km more or less parallel to the shoreline from the west coast to the southern coast where it reaches De Hoop Nature Reserve. It extends about 100m offshore and is extremely rich in marine life and biodiversity, containing about 14 000 different species.
The main algal species in South Africa are Ecklonia maxima and Laminaria pallida
Laminaria pallida prefer to stay in regions where there are rocky shores, this allows the laminaria to attach. Due to the height of the Laminaria, they provide protection for creatures that the open ocean does not often give. Invertebrates are just one of the organisms that live among the algae. Sea snails and other invertebrates feed on the blades (leaves) of the laminaria. Other organisms, such as sea urchins, feed on the holdfasts, which can kill the algae.
Ecklonia maxima is a dominant west coast species that forms extensive kelp beds from just north of Luderitz in Namibia to Papenkuilsfontein about 10 km west of Cape Agulhas, and very recently recorded also from Koppie Alleen, De Hoop, indicating a recent range extension of some 70 km. The kelp anchors itself by attaching itself to a rock or other kelp. The hollow stipe and gas-filled bulb enable detached sporophytes to float long distances.
The southeasterly wind feeds the Cape Peninsula in summer by bringing upwellings of nutrient-rich waters from the cold depths of the ocean, fertilising the kelp plants, allowing them to grow into giant forests. Wave action and water movement are also vital for kelp growth because they stir up the nutrients and enable the plants to absorb these nutrients through their fronds.
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Originally published at https://www.justscuba.co.za on February 11, 2021.