ESTUARIES IN SOUTH AFRICA

Main Page	General Information	Catchment Characteristics	Land and Estuary Uses	Water Quality
Threats	Hydrodynamics and mouth dynamics	Physical Features	Climate	References
VERLOREVLEI RIVER ESTUARY: Ecology

	Flora
	Phytoplankton/Diatoms

	Algae
	Large masses of filamentous green algae, including Chaetmorpha and Cladophora, are common in the channel, particularly between the railway bridge and the lower causeway, where the water is often stagnant and hyper saline (Ref. 6).
	Aquatic Vegetation
	Extensive beds of emergent aquatic macrophytes occur along the margins of the lake with Phragmites australis, Typha latifolia and sedges as dominants. Downstream of Redelinghuys there are fairly wide and open wetlands with patches of mixed sedges and reed communities along the course of the Verlorenvlei River over a distance of 11km. Dense reedbeds are present in the upper part of the lake. Myriophyllum spicatum, a submerged macrophyte, dominates large areas of the lake where the water is about 2m deep. The water lily, (Nymphaea capensis), a species which is becoming rare in South Africa due to destruction of wetlands, occurs in small numbers (Ref. 1).
	Semi-aquatic Vegetation

	Terrestrial vegetation
	The Verlorenvlei wetland is of significant botanical importance, because of its position at the transition between the karroid and fynbos vegetation types. The region therefore, has a high diversity typical of an ecotone area (Ref. 1).
	The different vegetation types are (Ref. 1): Strandveld - Seaward dune strandveld - Shrubby strandveld - Restoid strandveld Saltpan vegetation Lowland fynbos Dry mountain fynbos Mountain fynbos Karroid scrubland Marsh vegetation.
	The site also supports notable rare plant species, such as Ferraria foliosa, F. densepunctulata, Cerycium venom (presumed extinct) and Cullumia floccosa (Ref. 1).
	Fauna
	Zooplankton

	Aquatic Invertebrates

	Insects

	Fish

	Amphibians and Reptiles

	Birds
	In 1976, 934 and 1 371 waders were recorded respectively during two surveys in the lower reaches of Verlorenvlei (Ref. 7). Of these numbers, 95% were migrants. In a later survey (1983) of the whole Verlorenvlei, 3 655 waders were reported, of which 2 928 were migrants and 727 residents. This same survey yielded a total of 6 829 birds of 60 species in the environs of Verlorenvlei (Ref. 1). The vlei also provides feeding, nesting and roosting sites for 200 species of birds in the surrounding area. It is an important moulting area for Egyptian geese (Alopochen aegyptiaccus) and other waterfowl (Ref. 1).
	Waterbirds seen at Verlorenvlei include herons, egrets, ibises, spoonbills and flamingos. The presence of glossy ibises and African spoonbills is important, since these species are uncommon in the south-western Cape (Ref. 8). Flamingos appear at Verlorenvlei when other vleis, such as Rocher Pan (35km south) and Wadrifsoutpan (13km north) dry up. Flamingos are listed in the South African Red Data Book as requiring conservation (Brooke 1984).
	Other Red Data Book species include the little bittern and the Caspian tern. The area is possibly also an important moulting ground and summer refuge for ducks, with 600 Cape shoveller and 1 200 yellow-billed duck being observed in May 1979 (Ref. 1). In addition, Verlorenvlei is a type locality for several species of birds, including the white-backed duck (Thalassomis leuconotus) (Ref. 8).
	Up to 150 great white pelicans were counted by the Fitz Patrick Institute in 1976, representing 26% of the total south-western Cape population (Ref. 8). On 23 March 1982, 212 pelicans were counted. The great white pelican is rated as rare in South Africa, and therefore in need of special protection (Ref. 9).
	The vlei is also an important feeding area for the rare white pelican (Peleanus onocrotalus).
	Mammals
	Little information exists on mammal populations at Verlorenvlei. Archaeological and historical evidence suggest that larger mammals were present in abundance in the past, whereas they are non-existent today. A survey by Stuart (1981) indicates the presence of the 12 carnivore species and 11 other mammal species in the vicinity.