The Biodiversity of South Africa refers to the variety of living organisms within the boundaries of South Africa and its exclusive economic zone. South Africa is a region of high biodiversity in the terrestrial and marine realms. The country is ranked sixth out of the world's seventeen megadiverse countries, and is rated among the top 10 for plant species diversity and third for marine endemism.
This biodiversity is monitored and reported in terms of the continental terrestrial, inland aquatic, coastal, marine and the sub-antarctic Prince Edward Islands components. South Africa is a party to the Rio Convention on Biological Diversity, and has declared a number of protected areas, including national parks and marine protected areas which are managed by the national government. Continuing research and periodical reporting on the biodiversity of South Africa is the responsibility of the South African National Biodiversity Institute (SANBI) as directed by the Department of Environment, Forestry and Fisheries, and authorised by various statutory acts.
SANBI reports an estimate of about 67,000 animal species, and more than 20,400 plant species that have been described. Almost a quarter of the global cephalopod species, about 16% of elasmobranch species, 13% of the world's sunspiders (Solifugae), nearly 10% of the world coral species, 8% of seaweeds, 7% of vascular plants, 7% of the birds, 5% of the mammals, nearly 5% of butterflies, 4% of the reptiles, 2% of the amphibians, and 1% of the freshwater fish of the world are found in the country and its exclusive economic zone, including the Prince Edward Islands. Almost two thirds of South Africa's plant species, about half of the species of reptiles, amphibians, butterflies and freshwater fish, and about 40% of the estimated 10,000 marine animal species are endemic.
Global context Biodiversity is the variety and variability of life on Earth. It is typically a measure of variation at the genetic, species, and ecosystem level. and is not distributed evenly, generally being richest in the tropics. Marine biodiversity is usually highest along coasts in the Western Pacific, where sea surface temperature is highest, and in the mid-latitudinal band in all oceans. Biodiversity generally tends to cluster in hotspots, and has been increasing through time, but will be likely to slow in the future.
Estimates on the number of Earth's current species range from 10 million to 14 million, of which about 1.2 million have been documented and over 86 percent have not yet been described. More recently, in May 2016, scientists reported that 1 trillion species are estimated to be on Earth currently with only one-thousandth of one percent described.
The country is ranked sixth out of the world's seventeen megadiverse countries, with high levels of marine and terrestrial biodiversity. The main criterion for megadiverse countries is endemism at the level of species, genera and families. A megadiverse country must have at least 5,000 species of endemic plants and must border marine ecosystems.
South Africa is one of the smaller megadiverse countries, with a terrestrial area of about 1.2 million km2 and is rated among the top 10 for plant species diversity. The EEZ is about 1.1 million km2 and is rated third for marine endemism.
Measuring diversity Biodiversity is usually plotted as the richness of a geographic area, with some reference to a temporal scale. Types of biodiversity include taxonomic or species, ecological, morphological, and genetic diversity. Taxonomic diversity, that is the number of species, genera, or families, is the most commonly assessed type.
The estimated number of South African animal species as of 2018 is about 67 000, with 20 401 plant species described. This comprises about 7% of the world's vascular plants, 7% of birds, 5% of mammals, 4% of reptiles, 2% of amphibians and 1% of freshwater fishes. Less information is available on invertebrate groups, but South Africa has almost a quarter of global cephalopods, and some terrestrial invertebrate groups are very strongly represented.
Evolutionary history
The age of the Earth is about 4.54 billion years. The earliest undisputed evidence of life on Earth dates at least from 3.5 billion years ago, during the Eoarchean Era after a geological crust started to solidify following the earlier molten Hadean Eon. There are microbial mat fossils found in 3.48 billion-year-old sandstone discovered in Western Australia. Other early physical evidence of a biogenic substance is graphite in 3.7 billion-year-old meta-sedimentary rocks discovered in Western Greenland. More recently, in 2015, "remains of biotic life" were found in 4.1 billion-year-old rocks in Western Australia.
Since life began on Earth, five major mass extinctions and several minor events have led to large and sudden drops in biodiversity. The Phanerozoic eon (the last 540 million years) marked a rapid growth in biodiversity via the Cambrian explosion—a period during which the majority of multicellular phyla first appeared. The next 400 million years included repeated, massive, biodiversity losses classified as mass extinction events. In the Carboniferous, rainforest collapse led to a great loss of plant and animal life. The Permian–Triassic extinction event, 251 million years ago, was the worst; vertebrate recovery took 30 million years. The most recent, the Cretaceous–Paleogene extinction event, occurred 65 million years ago and has often attracted more attention than others because it resulted in the extinction of the dinosaurs.
The period since the emergence of humans has displayed an ongoing biodiversity reduction and an accompanying loss of genetic diversity. Named the Holocene extinction, the reduction is caused primarily by human impacts, particularly habitat destruction. Conversely, biodiversity positively impacts human health in a number of ways, although a few negative effects are studied.
Taxonomic biodiversity of a region may increase either by influx of species from other regions or by speciation within the region. The former is facilitated by physical connections to other regions of compatible habitability, by the mobility of the affected organisms at some stage of their life cycle, and by agents contributing to dispersal. Speciation in situ is facilitated by reproductive isolation and changes in the environmental pressures on the local populations. Many regions of high biodiversity or endemism arise from habitats which require unusual adaptations.
Biological realms
Terrestrial (continental)
The continental terrestrial component of the region lies within the Afrotropical biogeographic realm, which is one of Earth's eight biogeographic realms. It includes Africa south of the Sahara Desert, the majority of the Arabian Peninsula, the island of Madagascar, southern Iran and extreme southwestern Pakistan, and the islands of the western Indian Ocean.
Inland aquatic
Estuarine
Marine
According to the WWF scheme, the coastal waters of continental South Africa mostly lie within the marine realm of Temperate Southern Africa, with a part in the Western Indo-Pacific. The boundary between the Temperate Southern Africa and Western Indo-Pacific marine realms is near Lake St. Lucia, in northern KwaZulu-Natal, near the border with Mozambique.
The marine biodiversity of South Africa is the variety of living organisms that live in the seas off the coast of South Africa. It includes genetic, species and ecosystems biodiversity in a range of habitats spread over a range of ecologically varied regions, influenced by the geomorphology of the seabed and circulation of major and local water masses, which distribute both living organisms and nutrients in complex and time-variable patterns.
South Africa has a wide range of marine diversity with coastline in three oceans, two major current systems, major ocean frontal systems and benthic topography extending to a maximum depth of 5 700 m. There are 179 defined marine ecosystem types, 150 of them around South Africa and 29 around the sub-Antarctic territory of the Prince Edward Islands.
Coastal
Since 2018 the National Biodiversity Assessment has produced a separate coastal report, combining data from marine portions of the coastal zone with estuaries and dunes along with beaches and rocky shores, defining the coastal zone as an ecologically determined cross-realm zone spanning the coastal parts of the marine and terrestrial realms, and including all estuaries, within which relevant results from the constituent realms are presented together. This analyses biodiversity across the land-sea interface compares it with the non-coastal parts of the terrestrial and marine realms.
Vegetation types on the landward side of the coastal zone are included in the ecologically defined coast if they are purely coastal or have a coastal affinity, and least 70% of their area is within 10 km of the shore. On the seaward side, ecosystem types that are influenced by the land are considered to be coastal, and include ecosystems extending as far offshore as the back of the inner shelf, bays, and marine ecosystem types influenced by rivers. Estuarine Functional Zones (EFZs) are also considered to be part of the coast.
The ecologically defined coastal zone is estimated to comprise about 4% of mainland terrestrial area, but includes 186 of the 987 ecosystem types, high biodiversity, and many endemic species, particularly along the south coast. This is largely due to large variations in coastal conditions affected by the warm Agulhas Current on the east coast, and cool Benguela Current along the west coast, distinct variations in temperature and rainfall patterns and variations in geology.
Coastal parts of ecosystems tend to be hotspots of cumulative pressure, which often causes poor ecological condition in those areas. Ports and harbours have been identified as centres of cumulative impacts and ecological degradation. Intensive pressures on coastal areas include use of biological resources, coastal development, and mining. Coastal species of economic value which are accessible are likely to be over-exploited. Estuaries are often subjected to major flow modification due to upstream water use, which has adverse impacts on many coastal ecosystem types. For example, sand supplies to beaches and dunes are severely reduced, which affects erosion rates. Climate change and invasive species increase pressures on coastal biodiversity, and much of the pressure due to pollution is poorly understood.
60% of coastal ecosystem types making up 55% of the coastal zone area, have been identified to be threatened, with a high risk of biodiversity loss in 13 ecosystems, while 9% of the coastal zone area is protected, providing good protection to about 24% of coastal ecosystem types.
The three South African regions of high plant diversity and endemism all occur partly along the coast. They are the Maputaland-Pondoland-Albany Hotspot, the Succulent Karoo Region, and the Cape Floristic Region.
The coastal zone provides a rich variety of organisms useful to people as food, medicine, fuel and raw materials for construction and crafts. There are more than 220 coastal plant species recorded as useful for these purposes from South Africa.
Many coastal inhabitants rely to some extent on estuarine and marine fish and invertebrates as part of their diet, and the money saved by harvesting natural resources can be used for other needs, which is a significant benefit for economically marginal families. About a million people engage in recreational fishing, and the fishery is estimated to have a value of about R1.6 billion in 2018.