World Heritage Site - St Lucia Wetlands EarthCache

St Lucia Wetlands became a World Heritage site in 1999 (ref 914) thus the first site to awarded this in South Africa.

The St Lucia wetlands consist of thirteen contiguous protected areas with a total size of 234,566 hectares (the marine areas total 84,020ha.). The site is the largest estuarine system in Africa and includes the southernmost extension of coral reefs on the continent. The site contains a combination of on-going fluvial, marine and wind processes that have resulted in a variety of landforms and ecosystems. Features include wide submarine canyons, sandy beaches, forested dune cordon and a mosaic of wetlands, grasslands, forests, lakes and savanna. The variety of morphology as well as major flood and storm events contribute to ongoing evolutionary processes in the area. Natural phenomena include: shifts from low to hyper-saline states in the Park’s lakes; large numbers of nesting turtles on the beaches; the migration of whales, dolphins and whale-sharks off-shore; and huge numbers of waterfowl including large breeding colonies of pelicans, storks, herons and terns. The Park’s location between sub-tropical and tropical Africa as well as its coastal setting has resulted in exceptional biodiversity including some 521 bird species.

The Park comprises two geomorphic units: coastal plain and continental shelf. The coastal plain is the southernmost end of the Mozambique coastal plain. It encloses the lagoon-like lakes of one of the major estuarine systems of Africa. These are separated from the sea by high forested barrier dunes of wind-blown sand. To its north-west are the low Lubombo mountains in the adjacent Mkusi Game Reserve. The coastal geology within the site is a complex of terrestrial and marine sediments. The uppermost, the Cretacean St Lucia formation, is very rich in marine fossils which are exposed on the west coasts of False Bay and Lake St Lucia. Stratified Quaternary marine deposits related to marine transgression and regression have resulted in a series of prominent north-south oriented sandy dune ridges. The soils are largely infertile wind-redistributed grey and red sands over mudstone and clay pans. Riverbanks are alluvial.

The coastal dunes along the eastern edge of the coastal plain are unique for the height, variety and extent of their forest cover. Along the inter-tidal and infra-tidal coast, the coastline has long sandy beaches between reefs of beach rock. The dunes range between 50 and 170 meters high, the highest mapped being the Ntambama dune (172m). They contain good deposits of ore but since the reward of World Heritage Site Status the ore will never be mined!

Two types of coastal lake systems have formed behind the coastal dunes: estuarine (Lake St Lucia and Lake Kosi) and freshwater (Lake Sibayi, Lake Bhangazi North, Lake Bhangazi South, Lake Mgobezeleni).

The lake is supplied by five rivers, most of their catchments lying outside the boundaries of the Park. The rivers are seasonal, flowing during the wet summer months and reduced to isolated pools and seepage through bed sediments in winter.

The flora is diverse, having 152 families, 734 genera and 2173 species, approximately 9% of the flora of South Africa and 31% of the flora of KwaZulu-Natal, have been recorded in the Park.

The wetlands of this unique estuarine system include freshwater Phragmites australis - Cyperus papyrus swamp which covers approximately 7000ha in the Park, forming the largest protected wetland in South Africa; saline reed swamp on alluvium and islands in Lake St Lucia, dominated by Phragmites mauritianus; sedge swamp, mainly in the Mfabeni swamp.

Grassland types include hydrophilous grassland on sandy riverine soils dominated by Acroceras macrum and Ischaemum arcuatum; high-lying grasslands on sand.

Open woodlands include mixed Acacia/broad-leaved woodland (Hyphaene coriacea and Ziziphus mucronata) and mixed Acacia woodland (Acacia nigrescens, A.gerrardii, A.tortilis, A.nilotica) which provide grazing and browsing for herbivores. Thickets of mixed microphyllous and broad-leaved woodland subject to salt spray and wind occur on seaward-facing dune slopes (Eugenia, Brachylaena, Euclea, Diosporos and Mimusops species).

Forest types include swamp forest, rare in South Africa, covering 3,095ha (64% of the South African total) dominated by Ficus tricopoda, hygrophilous forest and Barringtonia forest. (B. racemosa). These occur on organic soils in hypo-saline drainage lines and marshes around freshwater lakes usually flooded with slow-flowing water after rains; mangroves, dominated by Bruguieria gymnorrhiza and Avicennia marina.

There are 97 species of terrestrial mammals in the Park including 13 internationally threatened black rhinoceros Diceros bicornis minor and 150 white rhinoceros Ceratotherium simum. The Park has the largest single populations of hippopotamus Hippopotamus amphibius (about 700) in South Africa. Populations of bottlenose Tursiops truncatus, humpback Sousa plumbea and spinner Stenella longirostris dolphins live in Park waters. Winter migrations of humpback whale Megoptera novaangliae and southern right whale Eubalaena australis can be seen.

The herpetofauna is rich: 50 amphibians and 109 reptiles: and one crocodile, 12 species of Chelonidae, 53 snakes and 42 lizards and chameleons. The Park is the main South African breeding ground for loggerhead Caretta caretta, and leatherback turtles Dermochelys coriacea, with estimated populations of 2500 and 750 females respectively. The population of Nile crocodiles Crocodylus niloticus of approximately 1500 animals over 2m long is one of the largest in Africa, The Park contains populations of 5 amphibians endemic to KwaZulu-Natal, 2 being nationally threatened, and 6 internationally and 20 nationally threatened reptile species.

The ichthyofauna includes nearly 85% of the reef fish species endemic to the west Indian Ocean region (399 species) 991 species have been recorded. including summer aggregations of ragged-toothed shark Tiburon odontaspis and whale shark Rhynchodon typus. The 212 estuarine species include the large Zambezi shark Carcharhinus leucas. The fresh water fish fauna comprises 55 species including 6 internationally threatened and 16 nationally threatened species. The Park encloses the largest estuarine prawn nursery area in South Africa.

The very diverse avifauna numbers 521 species which is 60% of the South African total, approximately 200 of which are water birds for which the Park is an important refuge. The 339 breeding species include 23 of the 97 migrant species. There are four species endemic to South Africa and 47 endemic or nearly endemic to the region. The Park is an important breeding area for the pinkbacked pelican Pelecanus rufescens, white pelican P. onocrotalus, African fish-eagle Haliaeetus vocifer, Caspian tern Hydroprogne caspia, goliath heron Ardea goliath.