South Africa
Information sheet for the site designated to the
List of Wetlands of International Importance
in terms of the
Convention on Wetlands of International Importance
especially as Waterfowl Habitat
COUNTRY
South Africa
DATE OF COMPILATION
Originally completed: Nov/Dec 1988
Updated: Oct 1995REFERENCE NUMBER
Not yet available
COMPILER
Originally compiled by:
Dr Robert Kyle
Fisheries Research Officer
PO Box 43
KwaNgwanase
3973
South Africa Tel (035) 5721011
Fax (035) 5721011 Updated by:
a) Dr Robert Kyle
b) M C Warda) PO Box 43
Kwangwanase
3973b) Private Bag X314
Mbazwana
3974NAME OF WETLAND
Kosi Bay
DATE OF RAMSAR DESIGNATION
28 June 1991
GEOGRAPHICAL CO-ORDINATES
26o 52'S - 27o 10'S
32o 42'E - 32o 54'EGENERAL LOCATION
The system is orientated on an east north-east to south south-west axis.
MAPS NUMBER 1: 50 000 2632 DD and 2732 BB
Bounded by Mozambique in the north and the Indian Ocean in east. The western border encapsulates the lakes of the Kosi System from a point on the Mozambique border ± 4 km from the Ocean. The border goes round much of the extant swamp forest around the system and in the south includes much of the catchment. In the north west the reserve boundary includes a narrow strip of land around the margins of the lakes.
The Kosi system is some 470 km north east of Durban. The nearest town is Ingwavuma, situated 105 km from the estuary, although the village of KwaNgwanase is 13 km from the KwaZulu Department of Nature Conservation camp on the north western shores of Lake Nhlange.
There is a good tar road to within 13 km of the site but the road then deteriorates to gravel between KwaNgwanase and the campsite and the condition can be very poor following heavy rain.
AREA (ha)
10 981.63 ha
WETLAND TYPE
A (Shallow marine waters)
C (Coral reefs)
E (Sand/shingle shores)
F (Estuarine waters)
G (Tidal mudflats, including intertidal flats and saltflats)
H (Salt marshes)
I (Mangrove/tidal forest)
J (Coastal brakish/saline lagoons)
K (Coastal fresh lagoons)
L (Deltas)
O (Freshwater lakes: permanent)
P (Freshwater lakes: seasonsl/intermittent)
Q (Saline/brackish lakes/marches: permanent)
R (Saline/brackish lakes/marches: seasonal/intemittent)
S (Freshwater marches/pools: permanent)
T (Freshwater marches/pools: Seasonsl/intermittent)ALTITUDE
Min: Sea level
Max: 102 mOVERVIEW OF SITE
The system is composed of four interconnected, roughly circular lakes (Makhawulani, Mpungwini, Nhlange and aManzimnyama), a broad channel leading to an estuary which opens to the Indian Ocean and three extensive areas of swamp. The lakes are separated from the ocean by a strip of forested sand dunes 600 - 2000 m in width. Numerous sandy mudbanks, emergent at low tide, occur in the lower part of the system. Principal habitats include swamp forest, Phragmites beds, mangrove forest (32 ha), dune systems with associated woodland, and coastal grassland, fresh and brackish water bays, lagoons; both salt and fresh (including artificial lagoons), tidal estuaries, permanent waters of estuaries and estuarine systems of deltas, intertidal marshes; includes saltmarshes, salt meadows, saltings, raised saltmarshes, tidal brackish and freshwater marshes, intertidal forested wetlands; includes mangrove swamps, nipa swamps, tidal freshwater swamp forests, brackish to saline lagoon with one or more relatively narrow connections with the sea, freshwater lagoons and marshes in the coastal zone; includes delta lagoon and marsh systems.
PHYSICAL FEATURES
13.1 Geology and geomorphology
The Kosi system lies within the pale sandy soils of the Mozambique coastal plain which overlie Cretaceous beds. The coastal dunes are composed of both Holocene and Pleistocene sand deposits. West of the coastal dunes no rocks or stones are to be found, although on the coast; rock ledges, shelves and outcrops occur. One such rocky outcrop near the mouth forms a small reef within the estuary, upon which a very diverse fauna may be found.
The Kosi system illustrates the phenomenon of segmentation, a process which transforms the system into circular water bodies each seperated by low beach barriers. The circularity of the lakes reflect the opposing wave energies generated by the prevailing winds. The system is made up of 4 lakes, plus a broad shallow channel leading to an estuary. There are no cut-off lakes behind the barrier dune system. The lakes are interlinked. The main lakes drain three large swamp areas through the Sihadhla, Naswamanzi and Sifazanene streams which are normally perennial flowing. This country is characterised by the prevalence of stagnant water and boggy ground due to a high water table.
13.2 Origins
There are two principal rivers which enter the system:
- Sidhadla River which rises in the Mtombeni pans, is approximately 30 km long and, after receiving contributions from a network of twelve principal tributary systems, enters Lake Amanzimnyama.
- Nswamanzi River which is approximately 15 km long, collects water from nine principal tributaries, and enters Lake Nhlange on its western shore.
13.3 Hydrology
Very little information is recorded on the hydrology of the Kosi system. There is a fairly strong seasonal inflow of fresh water into the head of the estuary. In 1976 the Department of Water Affairs installed seven gauge plates and two water-level recorders. Records are maintained by staff members of the KwaZulu Department of nature Conservation stationed at Kosi.
13.4 Soil type and chemistry
The bottom materials in the Kosi System are principally clean, white sands, particularly in the northenmost reaches where tidal influences are most marked. Sandy substrates are also characteristic even on steeply-shelving profiles and in the lake margins. The only silt is found in deeper waters, or as a thin layer overlying sand in certain shallow areas.
The sandy substrates of Kosi are characterised by a lack of fine particles, and are low in nutrient content. They contrast in these respects to the bottom materials of the deeper parts of the system where unconsolidated organic debris has collected. In these instances, the bottom materials are characterised by low dry weights and high volatile and nutrient values. They can be of considerable thickness and are black and hydrogen sulphide bearing. These materials originate in the marshes and swamps alongside the system and then naturally gravitate towards the deeper areas.
13.5 Water quality
Thermal properties
Lake Nhlange is a warm lake which exhibits a complex pattern of stratification during summer. Several thermoclines develop during summer because of strong northerly or southerly winds. In the cool season Lake Nhlange tends to develop homothermal characteristics at 18,5o to 19oC. In lakes Mpungwini and Makhawulani temperature layering is evident, so that bottom temperatures may be significantly warmer than the surface waters. In the well-mixed, shallow, tidal portion of the system sea temperatures become more evident. Water temperatures in the channels do not fall below 20oC in winter and attain 30oC in summer. In the shallow margins summer temperatures of 39oC have been recorded.
Transparency
The Kosi system is renowned for its clear water, as illustrated by Secchi values of 4,2 - 7,0 m. In 1967, 1% of subsurface illumination was measured at 6 m in Lake Nhlange.
Salinity
A classical transition from sea water at the mouth to fresh water in Lake Amanzimnyama (16 km distant) is evident. In the tidal basin salinities close to that of sea water may be encountered. These vary naturally with the tides, but it should be noted that on certain occasions at a low tide, salinities in this section of the system may drop to remarkably low levels.
The two lakes Makhawulani and Mpungwini both exhibit salinity layering. In Mpungwini a sharp, permanent halocline occurs at approximately 10 m, the bottom water being highly saline, with a high proportional ionic composition similar to that of sea water. The source of this deep salt layer is the sea and consequently these lakes are considered to be dominated by ectogenic meromixis.
Lake Nhlange is not similarly stratified, and is predominantly a freshwater lake, with a salinity range of 0.9 - 5.6o/oo. Here the water has an ionic composition different from the sea-water. In Lake Nhlange salinities fall, and yet the waters of Lake Nhlange are not considered simply as diluted sea water because the ion ratios between sea water and Nhlange water are markedly different. Lake Mpungwini is meromictic, but Lake Nhlange appears to be well mixed.
It has been suggested that the low salinities of Nhlange adversely affect the osmoregulation of many marine species of fish that would otherwise enter the lake.
Dissolved oxygen
Dissolved oxygen concentrations vary between 7.6 - 8.6 mg/l at the surface and 7.0 -7.7 mg/l at 10 m depth, but below this depth in Lake Mpungwini, the bottom waters become anoxic in winter and may contain hydrogen sulphide.
Other than the water in the hypolimnion of Lake Mpungwini, the waters of the Kosi system are well oxygenated. In Mpungwini oxygen falls to zero at 9 - 13 m depending on the season. This is due to abrupt temperature and salinity layering at this depth. Below the thermocline, the water may be hydrogen sulphide bearing. Such characteristics are regarded as a barrier to juvenile fish and other small organisms in their movements through the system, and consequently the shallows represent an important migration route. Very few fish are caught in depths > 6 m.
In Lake Nhlange, dissolved oxygen is found at all depths because the lake is not stratified and because circulation is effective throughout. It has been suggested that if the bottom materials in Lake Mpungwini become greatly disturbed, the whole lake could become temporarily anoxic.
Nutrient availability
In general terms nutrient levels are low and no abnormal nutrient additions occur which affect the system adversely. However, a substantial reservoir of nutrients lies on the bottom of the system in the form of organic detritus.
Nitrogen
In the Kosi system the recycling of nitrogen is assisted by the anaerobic reduction of organic nitrogen in the deep, organically rich areas of the system. Consequently the proportion of ammonia is substantial and some 50% higher than normal. Because of incorporation into biological materials and low volume interchange (through Mhtando channel), the total nitrogen concentration in Lake Nhlange is 50-100% higher than that in Lake Mpungwini-Makhawulani. An inexplicable phenomenon is the virtual abscence of nitrate in Lake Nhlange.
Phosphorus
With nitrogen:phosphorus ratios of 50:1, the concentrations of phosphorus in the system are considered as limiting or inadequate.
Pollution
- Heavy metals
In August 1976 low levels of heavy metals were encountered throughout the estuary.
- Pesticide residues
One of the most serious problems in Kosi relates to the fact that DDT (DDE and TDE) is apparent in the sediments of Lake Mpungwini and Makhawulani, and present in fish tissues in relatively high levels. The malaria control spraying operations of the KwaZulu Department of Health are clearly responsible.
The spraying of tsetse fly in the area has long since ceased and the dipping of the large herds of native cattle around the Kosi system (in toxaphene) is also not considered to present any particular pollution threat to the system.
13.6 Depth, fluctuations and permanence
Maximum water depths, with mouth open, are 31 m in Lake Nhlange, 18 m in Lake Mpungwini, 8 m in Lake Makhawulani, but only 3 m in the estuary. Lake aManzimnyama at the southern extremity, farthest from the sea, is very shallow with a maximum depth of 2 m.
The deepest area of Lake Nhlange is 42 m deep. Due to the shallow nature of the tidal basin about 70% of its area becomes exposed at low tide.
The Kosi system sometimes experiences cyclones which can cause a considerable water level rise in a relatively short time. Drastic water level rises can lead to the death of plant communities, for example mangrove communities died after the cyclone Claude (1965) had caused increased lake levels.
The mouth of the estuary is open throughout the year and subjected to regular and strong tidal movements, although this opening is considered to be maintained with difficulty. However, this exchange with the sea is the lifeline on which the system depends. The mouth varies in size with every tide, particularly during spring tides. It is generally 20-50 m wide and 3 m deep. It can vary in width from 5-100 m.
13.7 Tidal variations
Tidal effects are occasionally noticeable in Nhlange during spring tides particularly in late winter (low water level periods). The levels in Kosi are lower at low neap tide than at low spring tide because the water which enters the estuary on the high spring tide does not have time to leave before the next high tide starts rising. Outflow towards the sea is greater during summer, and water movements during winter are due to tidal effects. In all cases outflow speeds exceed inflow speeds.
13.8 Catchment area
The Kosi system lies on the coastal plain east of the Lebombo Mountains in the north-east extremity of the Ingwavuma district of Maputaland. The Kosi drainage system is ill-defined because of the pans, swamps and marshes which surround it. It is estimated to be approximately 500 km2 in extent. A small portion of the catchment (ie that draining into Lake Zilonde) is in Mozambique.
There are two principal rivers which enter the system:
- Sihadhla River which rises in the Mtombeni pans, is approximately 30 km long and, after receiving contributions from a network of twelve principal tributary systems, enters Lake Amanzimnyama. This river drains about 13 000 ha of swampy land before entering the southernmost lake.
- Nswamanzi River which is approximately 15 km long, collects water from nine principal tributaries, and enters Lake Nhlange on its western shore.
It has been suggested that only 5% of the total annual precipitation is borne by rivers/streams in the Kosi area, due to the high infiltration rate of water on the sandy coastal plain over which such rivers move. Small changes in drainage patterns could result in the isolation of Lake Nhlange because of its tenuous connection (the Mtando channel) to the sea. Therefore reports of swamp drainage at the source of the Sihadla River are viewed in a serious light.
13.9 Downstream area
None
13.10 Climate
Warm to hot and humid subtropical climate:
Kosi Bay falls within a climatic region which is one of the most well-watered areas in South Africa. The average yearly rainfall at Kosi Bay is 980 mm. Rain occurs mainly during summer from October to March and the highlight of the rain season is from February to March. Sometimes heavy showers fall in short periods with consequent floods which cause considerable damage. Although the rainfall is relatively reliable, droughts occur.
Cloudy weather during the summer months reduce the sunshine duration to approximately 45 % while the percentage in winter is approximately 70. The average daily maximum temperature extends from 28oC in January to 22oC in July but extremes can reach 43oC and 34oC respectively. Average daily minima are 19oC in January and 9oC in July while extremes can fall to 7oC and -1oC. Frost is virtually unknown, except occassionally in a few valleys in the interior.
The prevailing wind directions are north-east and south-west in almost equal proportions. The calm and clean winter weather makes this coast one of the most attractive holiday resorts in South Africa.
ECOLOGICAL FEATURES
Swamp forest
A characteristic feature of the swamp forest is the predominance of ferns as a ground cover, and conspicuous climbers such as Stenoclaena ternifolia.
Marshes, sedge and aquatic communities
Amongst the marshes ans sedges which surround the estuary or are marginal elements of the flora, Phragmites australis, Cladium sp and the fern Achrostichum aureum are dominant. Various semi-emergent plants, especially water-lilies (Nymphaea spp) are common along the edges of the system.
Mangal communities
a) Mangrove association
The mangrove community of the Kosi system comprises five different species, two of which (Ceriops tagal and Lumnitzera racemosa) are at the southernmost limit of their distribution, which means that Kosi is the only place in SA where they grow. The Kosi mangrove community is stunted and unimpressive, largely as a result of the unsuitable substrate. It occupies some 32 ha.
b) Barringtonia/Hibiscus association
This association is of equal, if not more importance to the Kosi system and is very common on the water's edge and often interspersed among the mangroves. These trees fulfil much the same ecological role as the five species of mangroves, in terms of bank stabilisation, provision of habitat and the contribution of detritus. Near to the estuary, and growing under saline conditions, is the rare tropical shrub, Caesalpinia bonduc.
Coastal dune forests
Dominant species include Euclea spp, Strelitzia spp and Mimusops spp and, in places, the cycad Encephalartos ferox occurs. One of the major problems in the Kosi system area was the destruction of the coastal dune forest communities alongside the system, particularly on the eastern side of the estuary. This situation arose as a result of the "slash-and-burn" method of cultivation which is practised by the local peasant community. Since the proclamation in 1982 the severity of the destruction has decreased maruedly.
Grassland/Open woodland/Palm communities
The undulating grasslands on the west of the Kosi system are made up principally of Urelytrum sp, among which are palm patches of Phoenix reclinata (date palm). Woodland vegetation predominantly comprises the umdoni (Syzygium cordatum), Trichilia sp, Albizia sp and Dialium sp.
Algae
The most common planktonic alga in the Kosi system is Microcystis sp, which is particularly noticeable in the uKhalwe inlet.
LAND TENURE
The site is a Nature Reserve administered by the KwaZulu Department of Nature Conservaton. The surrounding area is rural KwaZulu and consists of communally owned land falling under the Tembe Community (Tribal) Authority.
15.1 Legal status
The area was proclaimed as a nature reserve in 1987.
CONSERVATION MEASURES TAKEN
16.1 Management plans
Current management practices are to allow sustainable yield utilisation of the natural resources. The area is managed by the KwaZulu Department of Nature Conservation and attempts are being made to refine management in the light of better data on the resources themselves.
A fairly large, well trained and armed, team of uniformed officers patrols the area to control illegal forest destruction, hunting and fishing
Labour intensive schemes for the control of noxious weeds such as Pereskia aculeata are being carried out both to control the problem and to provide more employment to the local people.
Sustainable tourism is slowly being developed within the reserve with the active involvelemt of the surrounding rural communities.
Management category
Category IV - Nature Reserve
CONSERVATION MEASURES PROPOSED
The Kosi estuary has been rated foremost amongst Natal/KwaZulu's estuaries in terms of its conservation potential. It should thus be regarded as a system that should, without doubt, be very carefully managed and developed. It is one of the last Natal/KwaZulu estuaries with a fairly silt free nature as the catchment of many others has been degraded.
Research needs: The most pressing area of research is related to the physical management of the system. Hydrological studies should enable workers to construct a physical model of the Kosi system. This should enable an assessment to be made of the effect that fish traps are having on sanding up in the tidal basin, whether disused fences should be removed and whether the channel between the traps should be made broader or narrower.
LAND USE
Current management practices are to allow sustainable yield utilisation of the natural resources. The area is now managed by the KwaZulu Department of Nature Conservation and attempts are being made to refine management in the light of better data on the resources themselves.
Efforts are being made to increase the tourist utilisation of the area in order to give more benefit to the local people. 25 % of the gross revenue of the reserve goes to the local community therough the Community ( Tribal) Authority.
Labour intensive schemes for the control of noxious weeds such as Pereskia aculeata are being carried out both to control the problem and to provide more employment to the local people.
Subsistance agriculture - primarily of maize, millet and ground nuts in the dry areas and bananas, sugar cane and a crop called "madumbies" in the vleis and swamps. More and more the density of kraals is such that they (the homesteads) occupy much of the area, principally around the town of Kwangwanase.
POSSIBLE CHANGES IN LAND USE AND PROPOSED DEVELOPMENT PROJECTS
In the 19th century and again in 1981 plans were discussed to make Kosi Bay into a harbour such as was done at Richards Bay. This would have then given Swaziland better access to the ocean. These plans appear to have been shelved.
The dunes of the area are relatively rich in Titanium and other heavy metals and the mining of the dunes to retrieve these is always a possibility although there are currently no known plans.
DISTURBANCES AND THREATS
Swamp forest destruction by the "slash-and-burn" method of cultivation which is practised by the local people.
This technique appears to be not only wasteful and destructive, but also unrewarding, because the sandy soils which the locals cultivate are unproductive. In places the destruction of the natural forests has come down to the water's edge, and on steep slopes this is leading to serious erosion. The cultivation of the swamps for crops like bananas often leads to the canalisation and drying out of the swamps. This leads to the oxidisation of the peaty soils and the loss of the organic material. This not only renders the soil infertile it destroys its ability to hold water and stops the peat making process.
Afforestation (plantation) schemes in the catchment.
Large areas of the catchment, outside the reserve, are being put under Eucalyptus plantations. Many of the wetland areas are threatened by this and thus the freaswater supply to the lakes system. Sustained decrease in the freshwater inflow could result in a progressive rise in salinity in the lakes and a concomitant change in the ecological processes there.
The increasing use of fertilisers and chemicals in the catchment.
Eutrophication has not yet had a known serious impact as the local people use little fertiliser. Large areas of the catchment are under cultivation, however, and there are several schemes to encourage the local people to increase the use of fertilisers. Domestic sewerage has not been a problem but with increasing human habitation in the catchment and several domestic water supply schemes this may soon change.
Increasing (human) population pressure.
This has the result of an ever increasing demand for new land for cultivation and house building.
The scheme to make Kosi Bay into a harbour such as was done at Richards Bay.
The in-filling by sediment of the lakes of the system, due to swamp forest destruction and road and other development.
The changing (permanent) of the current salinity regime by changes to the profiles of the channels connecting the lakes and the ocean through boat traffic.
The encroachment of Phragmites reeds around the lakes and channels.
Noxious weeds - the principal one being Pereskia aculeata which grows and fruits well in the area.
DDT pollution
Gradual sanding up of the tidal basin. The fish traps used by the local community have often been perceived as contributing to the sanding-up of the tidal basin.
Bank erosion caused by the bow-waves from boats passing through the Mtando channel.
HYDROLOGICAL AND BIOPHYSICAL VALUES
SOCIAL AND CULTURAL VALUES
Zulu fishermen have used (and continue to use) the system since time immemorial. The lakes are extensively exploited by the local community for their fish resources mainly through a system of fish traps. Traditional spear fishing is also practised by the local community and they are also making increasing use of rod and line. Considerable numbers of recreational fishermen use the lakes . A legal gillnetting scheme was begun in 1992 and this allows the local community to use nets to catch fish in Nhlange lake on a controlled basis. Permits issued by the KDNC are distributed through committees of fishermen set up in neighbouring communities and this is an example of communities assisting the conservation authorities in the management of a resource within a reserve.
Some fruits of indigenous vegetation (such as the waterberry Syzigium cordatum ) are collected and consumed by the local inhabitants. Alcoholic drinks are prepared from various "drinking crops", for example sugar cane and the date palm Phoenix reclinata. Raphia palm leaves are widely used, mainly in the construction of rafts, and in the building of houses.
The lakes and ocean are often used by local communities for religious and cultural activities.
Firewood is collected extensively from within the reserve for use outiside.
NOTEWORTHY FAUNA
a) Zooplankton
Marine forms of zooplankton occur in the tidal basin and these forms extend into Lake Mpungwini at salinities of 12 to 21 ppt. The zooplankton density is highest on the eastern shores of Lake Makhawulani, where the residence time of the water is thought to be maximal. The zooplankton is made up principally of the copepod Pseudodiaptomus hessei. Athough over 50 taxa are present, settled volumes are less than 1,0 ml/50 m haul throughout the system. This sparseness of zooplankton is to be expected in a nutrient poor system such as Kosi.
b) Benthic fauna
The mollusc Musculus virgiliae (a lamellibranch) is present in vast numbers. The benthic population is diverse (30 taxa) and numerically rich, but not in the anoxic bottom of Lake Mpungwini and Makhawulani. Callianassa kraussi is confined in distribution to Lake Mpungwini and Makhawulani and the southern section of the tidal basin. It is considered to be the major infaunal organism of the system, in spite of its confined distribution.
c) Epifauna/Fauna from marginal vegetation
The marginal vegetation in the Mthando channel and in the margins of Lake Nhlange supports several species of animals. Common species include Musculus virgiliae, detritus-feeding crustaceans (amphipods, isopods, tanaids) and the crab Rhynchoplax bovis.
d) Prawns
The Kosi system is well known for its paucity of penaeid prawns due to the silt-free and nutrient deficient condition of the Kosi lakes substrates and waters.
e) Insect life
A wide variety of insects inhabit the Kosi system, some of which are important elements of the benthos (eg Clinotanypus sp, Chironomus sp). Others, such as the weaver or tailor ant (Oecophyllum smaragdina) are common in the mangroves.
A particular species of butterfly, a skipper Parnara micans, is regarded as endemic to Kosi (Campbell 1969). Charaxis protoclea azota is a red data butterfly species. It is a marginal species which occurs only in Kosi Bay in South Africa and is distributed from South Africa to East Africa.
f) Fish
At Kosi the different physical characteristics of the lakes, the proximity of the estuary to the Agulhas current, tropical water temperatures and the abscence of local silt-laden river systems result in a very diverse fish fauna. Kosi differs markedly from St Lucia in being a clear water system and a variety of marine piscivores (game fish), such as Caranx ignobilis, C. sexfasciatus (kingfishes), Sphyraeno jello (barracuda) and Scomberoides lysan (queen fish) penetrate as far as Lake Nhlange. They feed mainly on the various grey mullet species, Gerreidae and Rhabdosargus spp. The clear water and sandy substrates of the shallower areas provide suitable conditions for at least five species of Gerreidae (pursemouths) and this family probably forms an important link in the food web at Kosi since they are abundant.
The Kosi estuary is important in facilitating the change-over in diet of juvenile grey mullet (Mugilidae). The abscence of relatively high plankton densities at Kosi is in contrast to the situation at St Lucia and thus the pelagic food chains involving zooplankton-feeding fish, which are so important at St Lucia, are more or less absent at Kosi. Kosi also differs from most other southern African estuaries in having a rocky reef inside the mouth. Eighty percent of the species recorded in Kosi are found only on this reef. They represent an extension of a typical tropical Indo-Pacific reef fauna into the relatively quiet waters of an estuary and consist of, for example, surgeonfishes (Acanthuridae), damselfishes, butterflyfishes (Scorpaenidae) and wrasses (Labridae).
Freshwater species include:
Barbus paludinosus
B. viviparus
Clarias gariepinus
Aplocheilichthys johnstonii
A. katangae
Pseudocrenilabrus philander
Sarotherodon mossambicus
Tilapia rendalli swierstrae
T. sparrmanii
Kuhlia rupestris
Glossogobius giuris
Eleotris fusca
Eleotris melanosoma
Hypseleotris dayig) Mammals
The dominant mammal of the Kosi system is the hippopotamus (Hippopotamus amphibius) with a current population of around 60. Of the remaining 25 mammal species listed for the Kosi system, only the water mongoose (Atilax paludinosus), and clawless otter (Aonyx capensis) are estuary associated.
h) Birdlife
The prolific bird life of the Kosi system is essentially forest associated. From the list of 247 species for the system, only approximately 85 are water or estuary associated. Amongst the water/estuary associated species some are rare, notably Flufftail (Sarothrura spp), Whitebacked Night Heron (Gorsachius leuconotus) and the Crab Plover (Dromas ardeola). Several bird species at Kosi are also at the most southerly limits of their distribution and are not encountered elsewhere in SA. Although the avifauna is diverse, largely as a result of the undisturbed condition of the marginal vegetation along the water's edge, no single species is outstanding in terms of its abundance. This is possibly another result of a diverse habitat but one in which the overall nutrient status is low.
NOTEWORTHY FLORA
A variety of plant communities exist with numerous rare species.
- Coastal dune vegetation on the eastern margin of the system comprising plants, dune scrub and dune forest. Common species listed in Tinley's work (1976).
- Mangroves - 5 species found in the system, namely Rhizophora mucronata, Bruguiera gymnorrhiza, Avicennia marina, Lumnitzera racemosa and Ceriops tagal, the only area in South Africa with 5 species of mangrove and the only place where L. racemosa and C. tagal are found in South Africa.
- Aquatic vegetation includes submerged macrophytes (eg. Ceratophyllum demersum and Potamogeton pectinatus), semi-emergent plants such as Nymphaea spp. and Polygonum spp. and free-floating acquatics such as Lemna spp.
Hygrophilous grasslands and sedges are common in much of the lower-lying partially/periodically inundated areas; swamps and marshes occur where water is more permanent, with papyrus swamps being distinctive.
Extensive swamp forests occur in the area, this being the largest swamp forests in the country; due to the rarity of this forest type, this adds importance to the Kosi system. Common species include Syzygium cordatum, Ficus trichopoda, Voacanga thouarsii and Rauvolfia caffra as large trees, with Rapanea melanophleos, Myrica serrata and Halleria lucida as sub-canopy.
NOTE: A distinctive species is Raphia australis (a giant palm), Kosi being it's only natural habitat in the country and upon which the Palmnut vulture (a Red Data species) is dependant.
- Dryland plant communities consist of open (secondary) grasslands, open and closed woodlands (recognized by Syzygium cordatum, Sclerocarya birrea, Albizia adianthifolia, Trichilia emetica, Terminalia sericea and Apodytes dimidiata) and coastal forest paths. Within the coastal forest patches, common species include Dialium schlechteri, Mymenocardia ulmoides, Pteleopsis myrtifolia, Ficus spp, Strychnos spp, Mimusops caffra and Euphorbia spp, Drypetes natalensis, and Zanthoxylum capense.
Red Data plant species in the system include: (after Hall, et al 1980)
Vulnerable
Diospyros rotundifolia
Encephalartos ferox
Lumnitzera racemosa
Raphia australisRare
Ancylanthus monteiroi
Bridelia cathartica cathartica
Ceriops tagal
Cordyla africana
Craibia zimmermannii
Dialium schlechteri
Entada pursaetha
Dracaena usambavensis
Morus mesozygia
Nymphaea lotus
Pseudobersama mossambicensis
Sophora inhambanensis
Suregada zanzibariensis
Tapura fischeri
Uncertain
Ficus tremulaIn addition to these, other notable plant species include Tiliacora funifera, Scaevola sericea, Caesalpinia bonduc, Psilotum nudum, Mucuna gigantea, Inhambanella henriquessii, Platylepis glandulosa and Cheirostylis gymnochiloides.
- Coastal dune vegetation on the eastern margin of the system comprising plants, dune scrub and dune forest. Common species listed in Tinley's work (1976).
SCIENTIFIC RESEARCH FACILITIES
CONSERVATION EDUCATION
The area has very great potential for conservation education. It affords the opportunity for people to observe both the relatively pristine and utilised "mini- ecosystems" in the system. Access to the area is now good and accommodation is available. The local people are generally friendly and co-operative and when approached properly will happily explain how they utilise the resources of the area. There are many examples of the wise use of natural resources by the local people and recreational visitors.
RECREATION AND TOURISM
The area has special recreation potential and offers the possibility of walks through virtually undisturbed Coastal Dune forest and Swamp forest as well as open grassland and around the lakes.
Fishing for optic-feeding game fish (marine) is probably the best in South Africa (except in the open ocean) as the system has a low turbidity. Main target species of sport anglers are the Kingfish (Caranx spp) Seapike (Spyraena sp) and Rock Salmon (Lutianus argentimaculatus).
There is also the opportunity to observe the local people involved in their artisinal fishery using the traditional fish traps and spears.
The atmosphere of the area is generally tranquil and the weather is conducive to pleasant camping throughout the year. The winters are generally dry and not too cold.
Bird watching in the bush and lakes is most rewarding although the species diversity is low relative to Ndumu Game Reserve.
MANAGEMENT AUTHORITY
KwaZulu Department of Nature Conservation.
JURISDICTION
KwaZulu Nature Conservation Act
Magisterial District: Ingwavuma
Divisional Council: KwaZulu Legislative Assembly
REFERENCES
Many studies have been carried out and they are listed, more or less in full, in the following:
- BRUTON MN, AND COOPER KH. 1980. Studies on the Ecology of Maputaland. Grahamstown, Rhodes University.
- BEGG G. 1978. The Estuaries of Natal. Natal Town and Regional Planning Report. 41: 1 657.
- CAMPBELL GG. 1969. A review of scientific investigations in the Tongaland area of Northern Natal. Trans. R. Soc. S. Afr. 38: 305-316.
- HALL AV, DE WINTER B, and VAN OOSTERHOUT, SAM. 1980. Threatened plants of Southern Africa. South African National Scientific Programmes Report no 45, CSIR, Pretoria.
- HENNING SF & HENNING GA. 1989. South African Red Data Book - Butterflies. South African National Scientific Programmes Report No 158. Council for Scientific and Industrial Research, Pretoria.
- KYLE R. 1986. Aspects of the Ecology and Exploitation of the fishes of the Kosi Bay System, KwaZulu, South Africa. PhD Thesis. Natal University. PMB.
- MACLEAN GL. Robert's Birds of Southern Africa. 1985. John Voelcker Bird Book Fund, Cape Town.
- SCHULZE BR. 1974. Climate of South Africa, Part 8, General Survey. Weather Buro, Department of Transport, RSA.
- SMITH JLB. 1950. The Sea Fishes of Southern Africa. Central News Agency, South Africa.
- SMITHERS RHN. 1986. Land mammals of Southern Africa. Macmillan Publishers, Johannesburg.
- TINLEY KL. 1976. The ecology of Tongaland, 3: Kosi lake system. 69-140. Wildlife Society Southern Africa: Natal Branch, Durban.
Internal reports for the KwaZulu Bureau of Natural Resources are also available from the Department of Economic Affairs if specific subjects are requested.
Address: Department of Economic Affairs
Private Bag X23
ULUNDI
3838REASONS FOR INCLUSION
1. Criteria for representative or unique wetlands
- Kosi is undoubtedly the best "preserved" large estuary system in Natal. It is little degraded and supports a great diversity of fish and other aquatic fauna. The water is clear and deep relative to other Natal systems. It is still a "natural" system in that, unlike St Lucia, man has not yet significantly managed the system to what he sees as its best condition.
2. General criteria based on plants or animals
- There are many rare and threatened animals and plants in the area. There are 8 known "Red Data" fish of which most have their largest known populations in the Kosi System. Crocodiles breed there in small numbers and there are also several pairs of Palmnut Vultures. For details of species list and species of importance please refer to the relevant chapter of "Studies on Ecology of Maputaland" by Bruton and Cooper (See page 20).
- Kosi is a large, but relatively isolated, estuarine system. It is well over 100 km north or south to any other major estuarine system and this means that there is little transfer of truely estuarine animals between systems. If, on the other hand, Kosi ceased to function then it would be extremely difficult for estuarine species to move from north to south of Kosi. Kosi probably provides the only recruitment for several species of marine "spat" found along Natal coast(Bruton, 1980).
A distinctive plant species is Raphia australis (a giant palm), Kosi being its only natural habitat in the country and upon which the Palmnut vulture (Gypohierax angolensis), a Red Data species, is dependant for nesting and food.
OUTLINE MAP OF SITE
See Appendix 2
See attached list.
| If you have any comments on this page, or need more information, please contact John Dini at nat_jd@ozone.pwv.gov.za. |
| This page is maintained by the South African Wetlands Conservation Programme and was last updated on 12 January 1999. |