Get River-Wise at Ngwenya Lodge

On the sun-baked African savannah places of water are indeed places of life. For this reason some of the most interesting game and bird viewing experiences in the Kruger National Park occur along the perennial rivers which meander across this wildlife wonderland. The riparian habitat has a special appeal for it is here that a wide diversity of creatures both large and small conduct their lives in and amongst the stately trees, lush undergrowth and seemingly tranquil pools. Characterised by an air of anticipation, the Riverine Ecozone is not only home to the ever-elusive leopard but also a major point of convergence for herbivores and carnivores seeking life-giving water and sustenance. In addition, rivers are also home to a fascinating diversity of aquatic life forms many of which are never seen and are consequently not given much thought. Yet these "less obvious" organisms fulfil fundamentally important roles in maintaining the dynamic web of life within the Riverine Ecozone. Rivers are extremely dynamic entities being strongly influenced by their passage through diverse landscapes as well as season. The Crocodile River is one of six major rivers that play a critical role in sustaining the unique natural environments of the Kruger National Park. Being situated right on the banks of the Crocodile River, Ngwenya Lodge provides the perfect setting in which to get River-wise.

The Crocodile River From Catchment To Komatipoort.
The Crocodile River, formerly known as the "Ngwenya River", forms part of the greater Incomati River System whose catchment area drains some 10 526 sq. km of Mpumalanga and Swaziland and generates an estimated virgin mean annual runoff of 1 238 million cu. m. Along the 320km course from its source to its confluence with the Komati River, the Crocodile flows through a diversity of habitats and is joined by numerous major and minor tributaries. Interestingly more species (49) of fish inhabit the Crocodile River - more than any other river system in South Africa!

The Crocodile River rises at an altitude of 2150m above mean sea level in the Veloren Vlei nature reserve in the Mpumalanga highlands a short distance north-east of the popular trout fishing village of Dullstroom. From its source it flows past Dullstroom towards the escarpment. Just before cascading down into the fertile Schoemanskloof valley, the Crocodile River enters the Kwena Dam which was built to ensure a constant flow of water along the lower reaches of the river during the dry times. On occasions, prior to the construction of the dam, excessive water extraction for farming and industrial purposes during dry months would cause the Crocodile River to cease flowing. Even with the Kwena Dam, the Crocodile River stopped flowing in the Tenbosch area during the drought of 2003. Two species of fish, namely the Rainbow Trout (an alien) and the Chubbyhead Barb (indigenous), are found in the river above the Kwena Dam.

From the Kwena Dam, the Crocodile River flows eastwards through the scenic Schoemanskloof valley towards Nelspruit. On leaving the valley, the Crocodile River is joined at the Montrose Falls by a major tributary, the Elands River. Nine species of fish have been recorded in the river between the Kwena Dam and the Montrose falls. Below the falls the Crocodile River passes through intensely cultivated agricultural lands en route to Nelspruit. Some 23 km after Nelspruit the river enters the scenic boulder strewn Krokodilpoort (Crocodile Gorge).

The impressive lichen covered granite boulders of the Krokodilpoort Berge (Crocodile Gorge mountains) comprise some of the oldest exposed rock in the world dating back some 3 500 million years to the very dawn of time. Shortly after exiting the Krokodilpoort Gorge the Crocodile River is joined by another major tributary, The Kaap, at the village of Kaapmuiden. Known as the Middle Crocodile, the stretch of the river between the Montrose Falls and its confluence with the Kaap River is inhabited by 24 species of fish including the Southern Barred Minnow (Red Data) and other sensitive species like the Orangefin Barb and Shortspine Suckermouth.

The Lower Crocodile River stretches from Kaapmuiden to Komatipoort and forms the southern boundary of the Kruger National Park. More than 30 species of fish inhabit this stretch of the river. As the Crocodile River flows from the ancient granitic terrain of the Krokodilpoort mountains in the west to the more recently formed Basalts and Rhyolites of Lubombo mountains in the east it passes across a mind blowing geological time span of some 3400 million years.

At Komatipoort the Crocodile River and the Komati River converge to form the Incomati River which cuts through the Lubombo Mountains into Mozambique between the border towns of Komatipoort and Ressano Garcia. As the crow flies Ressano Garcia is only about 90km from the coast yet the Incomati River follows a long arching route of some 250 km across the Mozambique coastal plain before reaching the sea. Initially the river flows in a south easterly direction towards Moamba but then it changes direction sharply to the north, the north east and then to the south again before draining into the Indian Ocean through the Incomati Delta at Marracuene some 20km north-east of Maputo. En route to the ocean the Incomati River is joined by the Sabi, Massintonto and the Uanetze Rivers which slice through the Lubombo Mountains into Mozambique from the Kruger Park. In the Kruger Park the Massintonto River is known as the N'wasnitsontso which flows out of the Orpen Dam while the Uanetze River is known as the N'wanetsi which flows past N'wanetsi Private Camp.

Ecological Impacts
Between its headwaters in the Mpumalanga highlands and Komatipoort the ecology and health of the Crocodile River is impacted in many ways. Not only are vast quantities of water extracted by exotic tree plantations, agricultural irrigation, municipalities and industries but the river also becomes loaded with all sorts of pollutants (salts, heavy metals and pesticides) and silt.

Fertilisation of agricultural land and human settlements adjacent to the river lead to nutrient loading which in turn sustains unnatural algal growth. This detrimental impact, together with large quantities of floating noxious exotic plants such as Water Hyacinth (Eichornia crassipes), Water Lettuce (Pistia stratiodes), Parrot's Feather (Myriophyllum aquaticum) and Kariba Weed (Salvinia molesta), various exotic tree species and numerous unnatural fluctuations in water level creates challenging management problems for preserving the ecology of the river in a healthy condition. Invasive aquatic plants also cause management problems in dams and rivers in the Kruger National Park. For example, Sunset dam just outside Lower Sabi Rest Camp is often completely covered by infestations of Water Lettuce and Water Hyacinth. So what? you may ask. Well consider this - water loss from Eichornia crassipes can be double that from an open water surface! In order to ensure that the flow of the Crocodile River is stabilised a river control authority has been formed to take the interests of all parties into account.

The Crocodile River at Ngwenya Lodge
The most noticeable physical features of the Crocodile River as it flows past Ngwenya Lodge are the Rapids upstream from the main complex; the Deeper Pools above the rapids; the Main Channel interspersed with one or two small Islands; the River banks; the Reedbeds fringing the river and finally the vast Sandy Floodplain opposite the main complex. Each of these habitats has an interesting variety of plant and animal life associated with it.

In addition to these various habitats, the condition of the river is affected by seasonal changes in the volume and clarity of water flow. After the end of the rainy period, around late April, the river level gradually drops as does the sediment load carried by the water. From late May onwards water becomes crystal clear and the larger species of fish such as Mudfish, Yellowfish and Tigerfish can be seen swimming and feeding alongside the river banks and islands below the Game Viewing Deck of the main complex. Regular avian visitors during this period are the Great White Egret, Goliath Heron and Saddlebilled Stork which come to the river in search of fish.

Some Fish Facts
The Crocodile River boasts the richest diversity of fish species (49 species) of any river system in South Africa! To put this figure into a southern African and African context it is interesting to consider that as at 1992 some 270 species of fish had been recorded in the continental waters of southern Africa. Of these 160 species are grouped as primary freshwater fishes; 56 are secondary freshwater fishes; 37 are peripheral and sporadic marine species found in the lower reaches of rivers and coastal lakes and 5 species migrate from the sea to the rivers and back to the sea again during the course of their lifetime. There are also 18 alien fish species inhabiting southern African freshwaters. However, when compared with certain regions in Africa, the southern African fauna is relatively poor. Whereas most southern Cape rivers have only 3 or 4 indigenous freshwater species, the Zaire River system alone has 700 or more species of fish while the larger African Rift lakes such as Lakes Malawi, Tanganyika & Victoria have over 300, 220 & 200 species respectively.

In the rivers of the Kruger National Park a total of 50 species of fish have been recorded. Of these in excess of 30 species occur in the lower reaches of the Crocodile River (see species list).

Click here for fish species found in the lower Crocodile River.

These fish vary considerably in size from tiny Minnows to the much larger and hence more visible species such as Yellowfish, Mudfish and Tigerfish. Each species is adapted to live in a specific habitat (zone) within the river ecosystem.

Fish living and feeding in rapids which are characterised by fast flowing water are streamlined, strong swimmers with specially adapted mouths to remove algae from rocks as well as to hold onto them. Typical species found amongst rapids are the Mudfish, Catlet, Freshwater Eel, Barred Minnow and River Sardine.

Species associated with the quieter pools are the Barbs, Silver Robber, Mormyrids, Mozambique Tilapia, Sharptooth catfish and Squeaker.

Mudfish, Yellowfish and Tigerfish are associated with the main stream. Many riverine fishes make breeding migrations soon after the first major spring rains with the majority of fish moving upstream after the Spring floods. Tigerfish, however, migrate downstream to breed in the shallow floodpans of Mozambique.

Speaking of Tigerfish you can pitch your skill against these fierce freshwater gamefish in the Komati River only 15 minutes from Ngwenya. Fly-fishers should head for the ITAG tiger fish conservancy where fishing is on a catch and release basis. Get all the details re requirements such as licenses and permits from Domien van Buynder on 083-273-8525. For other stretches of the river fishing licenses and valuable advice on the best spots, bait etc. can be obtained from Moosas in the main street of Komatipoort. As with Birding, Tigerfishing is best during the hotter summer months. Be sure to keep an eye open for hippos an crocodiles whilst fishing. Besides fish, many other creatures associated with the Riverine Ecozone perform vital roles in maintaining the ecology of the river in a healthy functional state. There are amphibians, reptiles, mammals, birds and last but certainly not least the myriads of insects.

Obvious Physical Features Of The Crocodile River At Ngwenya

The Floodplain
The most obvious visual feature associated with the Crocodile River as it passes Ngwenya is the floodplain. Not only is the floodplain aesthetically appealing but more importantly its sparsely vegetated surface allows for excellent game spotting from the Lodge.

Vast numbers of spoor imprints on the sandy surface reflect the movement of game to and from the river and reedbeds in search of water and sustenance. Vegetation growing on the floodplain is adapted to withstand periodic inundation and scouring by floods. The floodplain, bare riverbanks and sandy islands are favoured habitats of Sandpipers, Plovers and Dikkops.

Bee eaters can frequently be seen hawking insects over the floodplain while cormorants favour the islands for drying their wings between bouts of fishing. Egyptian Geese spend their days flying noisily to and fro along the riverfront.

The Reedbeds
The most obvious form of plant life lining the riverbanks and islands at Ngwenya is the common reed, Phragmites australis, which forms extensive reedbeds. The common reed is an important fodder source for many species of animals which feed along the river. In addition the reedbeds provide shelter to animals and valuable nesting sites to many species of birds. Of particular significance to game viewing at Ngwenya is the fact that the reedbeds occur mostly along Ngwenya's side of the river. This means that there is a very good likelihood of having game come across the river to feed, particularly during the dry season.

In fact it's not uncommon at Ngwenya to have Bushbuck, Kudu, Waterbuck, Hippo, Elephant and Buffalo approach within meters of the river front chalets and hides. Bird life specifically associated with the reedbeds at Ngwenya includes a variety of L.B.J's (Prinias, warblers etc.), Natal Francolin, Weavers, Bishop Birds, Burchell's Coucal, Crakes, Moorhens, Flufftails and last but by no means least the African Finfoot which prefers to swim under overhanging banks and reeds. The Hadeda Ibis and Hammerkop are also common along the river as are Fish Eagles, Pied and Giant Kingfishers, Egrets, storks (saddlebill, woolly-neck and yellow-billed) and Herons (goliath, purple and green-backed). During the summer months you may even see Ospreys hunting for fish along the river.

Riparian Vegetation
Dense bush and trees growing alongside the perennial rivers which cut across the Kruger Park constitute important bird migration corridors between the Mozambican Lowlands and the indigenous forests of the escarpment. These lifelines through the wilderness provide food, breeding sites and shelter for all sorts of life forms. Sadly, farming activities between Kaapmuiden and Komatipoort have all but destroyed the riparian vegetation along the southern side of the Crocodile River.

Common trees associated with the riverine eco-zone at Ngwenya include Ficus sycamorus (Sycamore fig), Schotia brachypetala (Weeping boer-bean), Lonchocarpus capassa (Apple leaf), Ziziphus mucronata (Buffalo thorn), Spirostachys africana (Tamboti), Trichilia emetica (Natal mahogany), Diospyros mespiliformes (Jackalberry), Combretum imberbe (Leadwood), Combretum apiculatum (Red bushwillow), Lannea schweinfurthii (False marula) and Acacia nigrescens (Knobthorn). Along the woodland margin of the opposite bank Terminalia sericea (Silver cluster-leaf) trees can be seen (see Get Tree-wise).

Between August to October the blood-red flowers of the Flame Creeper (Combretum microphyllum) which scrambles over shrubs and trees alongside the river adds a dazzling splash of colour to the dry landscape. Common birds seen and heard amongst the riparian vegetation at Ngwenya include the Purplecrested Lourie, Kingfishers (brownhooded, woodland, pygmy and malachite), Green Pigeon as well as various species of Robins, Bulbuls, Flycatchers, Shrikes, Tchagras, Sunbirds, and Woodpeckers.

References and acknowledgements

• Deacon, A. 1994. Kruger's Rivers. Custos. National Parks Board. March 1994
• Pienaar, U. de V. 1978. The Freshwater Fishes of the Kruger National Park. National Parks Board of Trustees, Pretoria.
• Skelton, P 1993. A Complete Guide to the freshwater fishes of Southern Africa. Southern Book Publishers
• Thame, R. 1998. The Crocodile River. Journal of The Wildlife and Environment Society of S.A. Vol 52 No. 5

Dr. Andrew Deacon of the South African National Parks Board is thanked for providing the list of fish recorded in the stretch of the Crocodile River along the Southern boundary of the Kruger National Park.

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