Figure 9.2: Ocean ecosystem.- Coral reefs: are found in the warm, clear, shallow waters of tropical oceans around
islands or along continental coastlines. Coral reefs are mostly formed underwater from
calcium carbonate produced by living coral. Reefs provide food and shelter for other
organisms and protect shorelines from erosion. South Africa has only one coral reef
in the subtropical ocean waters north of Lake St. Lucia in northern KwaZulu Natal.
Figure 9.3 shows a typical coral reef system.
Figure 9.3: Coral reef.- Estuaries: are partially enclosed areas of fresh water and silt, from streams or rivers
which mix with salty ocean water. Estuaries represent a transition from land to sea
and from freshwater to saltwater. Estuaries are biologically very productive areas and
provide homes for a wide variety of plants, birds and animals.
Marine biomes of South Africa
South Africa’s long coastline stretches for over 3000 kilometres, from Namibia in the West to
Mozambique in the East. There are a few key features to note about South Africa’s coastline
and marine biomes. South Africa’s coastline is rugged, as rocky shores are exposed to high
wave energy. Coastline generally experiences high wind for most of the year. There are up
to 343 estuaries found along the coast, two thirds of which are found on East Coast between
Cape Padrone in the Eastern Cape Province and Mtunzini in KwaZulu-Natal. The Eastern
region receives the highest rainfall, mostly during summer. South Africa’s east coast has rel-
atively warm waters (20-25 degrees C), the West by colder Atlantic waters (9-14 degrees C)
and South by intermediate temperatures (16-21 degrees C). The Benguela Upwelling System
on the South-West coast supports large numbers of marine animals. Agulhas current off the
East Coast has a smaller quantity of fish but a greater diversity of species. Abundant oppor-
tunities exist for tourism, recreation, food, export and associated economic development.
Chapter 9. Biospheres to ecosystems 259