It is thought that kelp forests first appeared in the Miocene era between five and 23 million years ago. Kelp refers to marine algae in the order Laminariales (phylum: Ochrophyta). Four species of kelp are found around the South African coast, with Ecklonia maxima being the most familiar as it is often washed up on beaches following heavy storms. Kelp forests are formed when large brown macroalgae plants occur in high density. These forests are found across the globe in temperate waters and in the polar coastal oceans. As recently as 2007, kelp forests were discovered in the tropical waters near Ecuador, but these are the only known kelp forests in tropical waters. There are approximately 30 species of kelp worldwide, with kelp forests covering approximately 25% of the world’s coastlines. Kelp can grow quickly, and some species can grow as much as 45 – 60cm per day. The most notable kelp forests are found on the coasts of southern Africa, the West Coast of the United States, Argentina, Chile, southern Australia, and several northern European coasts.
Fun facts about kelp forests
- Technically, kelps are not plants but large algae from the same family as amoebas and moulds.
- Kelp extracts nutrients and minerals from the surrounding water, not the soil.
- The CO2 emissions of dairy cows can be reduced by up to 50% by supplementing their feed with seaweed.
- When kelp starts to decompose, it yields methane and sugars that can be converted into ethanol, a powerful form of biofuel.
What is a kelp forest?Kelp forests are areas where kelp plants occur in high-density groupings. These groupings usually occur in cold, nutrient-rich, shallow coastal waters. Kelp forests are dynamic ecosystems and provide habitats for many animals and other plant species. Just like forests found on land, kelp forests have multiple levels. The canopy is formed by the floating fronds of large species like sea bamboo, the stipitate is made up of stiff kelps that rise like small trees (like split-fan kelp), and some kelps like spined kelp lie directly against the seafloor. These types of kelp support populations of other algae and sessile animals that live on the seafloor. As a keystone organism, kelp plays a vital role in the ecosystem’s health. Kelp forests provide a source of food and shelter to a variety of species including fish, crayfish, sea cucumbers, limpets, filter feeders, and a range of fish species.
Habitats and lifestylesSeagrass and mangrove forests are found close to shore and estuaries, but macroalgae (large algae) tend to grow close to shore and in rocky areas where they can use their holdfasts (root systems) to anchor themselves. Like terrestrial plants, kelp needs sunlight to photosynthesise. Unlike plants, however, kelp extracts nutrients directly from the water around it. Kelp forests are vital habitats for thousands of unique species. Their rapid growth and conversion of carbon dioxide into energy make them an essential source of food for animals like abalone and urchins. The sheltered environments amongst the kelp serve as refuges and nurseries for countless species of fish. Even shore habitats, such as human settlements and bird nesting sites, are often protected by offshore kelp forests that dampen the effects of waves and prevent erosion of the coastline.
Kelp Forest ExhibitLiving kelp forests are currently only displayed in a handful of aquariums in the world. In our Kelp Forest Exhibit, three species of giant kelp provide shelter for an array of local fish, which drift amongst the kelp fronds. Our visitors are mesmerised by the hypnotic sway of the tall kelp plants and the play of dappled sunlight on silver fish scales. The Kelp Forest Exhibit holds 800 000 litres of water and a myriad of endemic fish including white steenbras, galjoen (South Africa’s national fish), red stumpnose, and spotted gully sharks. The exhibit is open to the sky so that the kelp plants can receive sunlight to photosynthesise. The optimal water temperature of between 12 and 15°C is achieved by large chillers. Kelp grows incredibly fast and must be replaced regularly. The Aquarium’s collections team often go out to sea to carefully collect kelp from the rocky reefs off Robben Island and Bantry Bay.
The many uses of kelpThe word "kelp" is derived from one of the plant’s earliest uses – being burnt to make soda ash, a component in glass. The brown seaweed produced ash which contained a lot of iodine, which would often result in undesirable colour tints in the glass. This type of ash was given the name "faulty" or in Latin, culpa (think culprit or culpable). This name eventually morphed into "kelp" for the ash and soon, people started using the word to describe the seaweed too. Kelp and other brown algae are rich in a carbohydrate called alginate which is extracted and used to make a variety of food products that require thickeners such as jam, ice cream, sauces, salad dressings, pet food and toothpaste. It also has many health benefits due to its high concentration of vitamins and minerals. Kelp is also the best natural source of iodine which is of benefit to thyroid hormone production. It is also an amazing source of plant-based calcium.