Introduction
The South African coastline stretches for about 3000 km between the international border with Namibia in the west and the Mozambiquen border in the east (DEAT, 1998)
(Figure 4.1 Main features of the South African coastline and ocean systems).
South Africa has full territorial sovereignity up to 12 nautical miles offshore and controls the exploitation of natural resources up to 200 nautical miles to sea from the coastline [according to the United Nations Law of the Sea Convention (UNCLOS) 1982]. This area of sea up to 200 nautical miles offshore is called the Exclusive Economic Zone (EEZ), includes the area around the Prince Edward Islands, and covers an area approximately 1.3 million square kilometres in extent. Within the EEZ South Africa controls all economic and resource management activities.
The South African coastline is rugged, its rocky shores exposed to high wave energy, has very few truly sheltered bays and is dominated by strong winds throughout much of the year. Eighty per cent of the 3000 km coastline consists of sandy beaches usually backed by low sand dunes. Approximately 1 to 2 million tonnes of sediment are transported past any given point on either the east or west coast each year. The driving force is the predominantly south westerly swell which gives rise to a net littoral drift along both coasts. The rocky shores support a rich flora and fauna and in many areas provide a rich food resource for subsistence dwellers along the coast.
There are 343 estuaries or river mouths along the coast between the Orange River at the Namibian border on the west coast and Ponta do Ouro at the Mozambiquen border on the east coast. Two thirds of all the estuaries are located on the east coast between Cape Padrone in the Eastern Cape Province and Mtunzini in KwaZulu-Natal, the eastern region of South Africa receiving a major share of South Africa's rainfall.
|
Estuaries are natural systems that are transitional between rivers (freshwater) and the sea. Because much of South Africa is semi-arid with great climatic variability within and between years, few of the estuaries fit conveniently into the northern hermisphere definition of such systems in having a perennial inflow of freshwater and tidal action. In South Africa an estuary is considered to be that portion of a river system which has, or can from time to time, have contact with the sea. Hence, during floods an estuary can become a river mouth with no seawater entering the formerly estuarine area. Conversely, when there is little or no freshwater input an estuary can be isolated from the sea by a sandbar and become a lagoon which may become fresh, or hypersaline, or even completely dry.
|
Along the east coast the continental shelf is generally narrow or non-existent. Off the south coast of the continent the shelf forms the large triangular Agulhas Bank. The Agulhas Bank is one of the two marine regions off South Africa that are of economic and biological importance, the other being the Benguela upwelling region along the west coast. Extensive exploration for oil and gas has been undertaken on the Agulhas Bank. Gas and oil fields are being exploited commercially, albeit on a small scale by global standards.
South Africa's eastern seaboard is characterized by relatively warm sea temperatures (20-25°C), the west by cool water (9-14°C), and the south by intermediate temperatures (16-21°C). Additionally there are the seas around the Prince Edward Islands which lie in the vicinity of the Subtropical Convergence.
The rich Benguela Upwelling System off south-western Africa supports large populations of epipelagic, midwater and ground fish, and high numbers of bird and mammalian predators. The Agulhas Current of the east coast has a smaller quantity of fish, but a greater diversity of species. In addition to the resident populations, many species, including whales, seabirds and tunas, migrate to or pass South Africa at certain times of the year.
The coastal and marine resources provide opportunities for economic and social activities that include: fisheries, agriculture, mineral resource exploitation and a range of development opportunities. The coast and its many estuaries are also highly valued for recreation. The sustainability of South Africa's coastal and marine systems and resources is important since they constitute a rich and diverse national asset which is sensitive to human-induced and environmental pressures.
There are gaps in scientific understanding of the functioning of South African coastal and marine systems. Much of the existing knowledge relates to fisheries, particularly those of the Benguela upwelling system, intertidal and estuarine ecology, coastal processes and the physical oceanography (particularly of the surf-zone)and marine geology of the continental shelf. (Figure 4.2 - Major Ocean Currents and Fisheries Resources). By contrast, the terrestrial components of the coastal zone, in particular the impacts and sustainability of land-based human developments, are less well researched.
South Africa has international legal obligations and a responsible role to play in the management and use of its coastline; e.g. the Sea Shore Act and its links to the Maritime Zone Act which claims maritime and economic boundaries for South Africa in accordance with international law (Henderson, 1996). South Africa is also a signatory to the World Conservation Strategy of the IUCN. One of the means by which this strategy is being implemented is the Sea Fisheries Act, Act 12 of 1988 which includes as policy guidelines, the conservation of marine ecosystems and the optimal and sustainable utilisation of marine resources (i.e. by meeting present needs without over-harvesting and reducing the ability of the system to provide for the needs of future generations).
|
There is also information about Terrestrial Ecosystems in the following reports:
|
|
Metropolitan reports:
|
 |
|
|
|
|
|
|
|
Copyright © 1999 Department of Environmental
Affairs and Tourism. All Rights Reserved.
Site maintained by the Directorate Environmental Information and Reporting
Last update: October 1999
| 
.gif){kind=small}