4.6 ZAIRE - Ramsar Sites Information Service

4.6 ZAIRE 

Introduction 

Zaire is the third largest country in Africa, after Sudan and Algeria, and 

the fourth most populous. With an area of 2 345 410 km 2 , and 33 944 000 

people (1983), it has the comparatively high population density of 13.6 

persons/km 2 . It lies across the equator, reaching 13°25'S in the 

southeastern extremity, and 5°23'N in a bend of the Bomu River on the 

northern frontier. It is bounded by Angola in the southwest, Zambia in the 

south, Tanzania, Burundi, Rwanda and Uganda in the east, Sudan and 

The Central African Republic in the north, and Congo and the Cabinda 

enclave of Angola in the west. It is has an Atlantic coastline of 40 km at 

the mouth of the Zaire River, between Angola and Cabinda, and extends 

some 2099 km from east to west and 2062 km from north to south. 

The eastern border is mountainous, all the way from Zambia to Uganda. 

The mountains of Shaba (Katanga) Province in the extreme SE rise to 

1889 m asl at Mt. Kiapulka, and along the western side of Lake 

Tanganyika the Mungila Mountains rise to more than 2000 m in several 

places. Beginning at the northern end of this lake the Mitumba Mountains 

run north to Uganda, reaching over 3000 m asl near Uvira 

(3°24'S/29°05'E) and along the western shore of Lake Kivu, while to the 

north of this lake they reach 4507 m asl at Mt. Karisimbi 

(1°31'S/29°27'E) and 3645 m asl at Mt. Sabinyo (1°23'S/ 29°36'E). This 

same chain again rises above 3000 m asl near Lubero (0°16'S/29°45' and 

0°10'S/29°40'E) and to a maximum elevation of 5110 m asl at Mt. 

Stanley (0°24'N/ 29°55'E). Mt. Aburo (2°01'N/30°50'E), at 2437 m asl, is 

the highest point at the northern end of the chain. Along this border, which 

follows the western rim of the Great Rift Valley, there are large areas of 

very high land. In the vicinity of Mt. Stanley alone, 35 000 ha rise 

above 3000 m asl, and along the entire mountain chain, a total of more 

than 4 275 000 ha lies above 1500 m asl. The southern and northern 

borders of Zaire are situated on elevated plateaux which slope gently 

towards the interior, but with numerous scarps so that almost all rivers 

flowing of f the plateaux to the central depression traverse several 

waterfalls or rapids. The southern plateau reaches heights of 1500 m asl 

on the Zambian border, but mostly lies between 500 and 1100 m asl, while 

the northern plateau is 500-700 m asl. 

A lake occupied the central depression of the Zaire Basin during the 

Pliocene, and the present effluent stream, the lower Zaire River, arose

when a coastal river cut back to capture the lake water before the end of 

that epoch. The lake was thus drained, but a large swampy and seasonally 

flooded area now occupies the western, lowest, part of the basin. Here 

Lakes Tumba and Mai Ndombe may be regarded as remnants of the huge 

Pliocene lake. Although during the dry phases of the Pleistocene the 

vegetation of the Zaire Basin was drastically altered, the river system has 

persisted with comparatively little change throughout the Quarternary, 

and indeed the entire Zaire Basin has been characterised by 

environmental stability over very long time periods, which in concert 

with the wide range of habitats it provides has favoured speciation. Thus 

669 species of fish have been described from the river system, of which 

558 are endemic, and it may well be that before zoological exploration is 

complete, over a 1000 fish species will be identified. Almost equally 

remarkable are the 22 different freshwater crabs (Potamonidae) so far 

described. 

More than 90% of Zaire drains to the Zaire River. The two principal 

Zairean headwater streams of this river, the Lualaba and Lufira, rise in Shaba 

in the southeast, close to the Zambian border at the points 11°52'S/26°25'E 

(Lualaba) and 11°52'S/26°52'E (Lufira). The Zaire River is called the 

Lualaba in its upper course, and at first flows north, then west and south, 

crossing the equator twice in a great arc as it traverses a vast swampy 

basin over 1050 km from east to west and up to 850 km from north to 

south. Here, and extending into the neighbouring state of Congo, over 65 

000 000 ha of very flat lowland lies between the 300 and 500 m contours 

in an ancient depression. This depression was invaded by the sea during 

the Mesozoic, subsequent to which its basin-like nature has been 

emphasized by persistent subsidence at the centre and compensatory 

uplifting of the margins, so that now, at the western extremity, the Zaire 

River traverses the low rim on its way to the sea. It flows through a gorge 

some 360 km long and containing no less than 32 rapids, between 

Kinshasa (4°18'S/15°18'E) and Matadi (5°50'S/15°52'E), descending in 

this section, from 307 m to 3 m asl. From the last rapids to the Atlantic 

Ocean is a distance of about 150 km, and the river is tidal for the last 95 km. 

Even below Matadi it flows through narrow gorges, and where it enters the 

ocean its bed occupies a deeply graven submarine canyon. Only in the 

northeast is there a part of Zaire which does not drain to the Zaire River. 

Here, on the border with Uganda, some short streams enter the Nile Basin 

via Lake Edward, the Semliki River and Lake Albert. 

Climate 

Rain falls over the central basin throughout the year, but is more seasonal 

on the borders. A broad per-humid belt extends inland along the equator

from the Atlantic coast, over Gabon, across Congo and into Zaire. 

Throughout this belt, which reaches 3°40'S, but only 1°N, mean annual 

rainfall exceeds 1800 mm. In its central section a vast area around Boende 

(0°15'S/20°51'E) receives more than 2000 mm. In the east another vast 

area, mainly south of the equator, extending into the basin from the 

mountains of Rwanda and Burundi, also receives mean annual falls in 

excess of 2000 mm, while the western slopes of the mountains near 

Bukavu (2°30'S/28°50'E) receive up to 2800 mm. Mean annual rainfall at 

Kisangani (= Stanleyville, 0°32'N/25°14'E) at the eastern end of the Zaire 

Basin, 415 m asl, and just north of the equatorial rainbelt proper, is 1703 

mm. October is the wettest month with falls of over 200 mm, while 

December, January and February are the driest months. Mean monthly 

rainfall at Kisangani in January is 50 mm. However, 110 km to the south, 

Ubundu (0°24'S/25°30'E) receives over 1800 mm/yr, and 215 km SE, 

Lubutu (0°45'S/26°37'E) receives over 2000 mm with no distinctly dry 

months. 

There is cloud cover over the equatorial region for much of the year and 

incident solar radiation is lowest there. It is less than 130 Kcal/cm 2 /yr in a 

zone extending from the coast inland over the western part of the central 

basin, including Kinshasa, Lake Mai Ndombe and the entire courses of the 

Lukenie and Lokoro Rivers. At the far eastern side of the basin Lubutu 

receives 140 Kcal/cm 2 /yr and the mountainous border with Rwanda and 

Burundi about 150 Kcal/cm 2 /yr. Radiation increases progressively away 

from this equatorial cloudy zone towards the borders, north and south. 

Thus at the far end of the basin Kisangani and Kibombo 

(3°58'S/25°54'E) both have mean annual receipts of 145 Kcal/cm 2 . 

Along the northern border Bangui (4°23'N/18°37'E), Mobayi-Mbongo 

(4°21'N/21°10'E), Bondo (3°47'N/23°50'E) and Bambesa 

(3°25'N/25°43'E) receive 165-170 Kcal/cm 2 /yr. In the southeast the 

central part of Lake Tanganyika, and Lake Mweru, both have mean annual 

receipts of 170 Kcal/cm 2 , while farther west the Upemba Lakes 

(8°37'S/26°24'E) receive 166 Kcal/cm 2 /yr, and the southern central 

border with Angola 145-155 Kcal/cm2/yr. 

Sunshine follows a slightly different pattern. The coast receives 1700 

hours/yr, decreasing up the Zaire Estuary to 1300 hours/yr at Matadi. From 

here passing inland, sunshine increases to 1650 hours at Kinshasa and 2000 

hours/yr at the western end of the interior basin. Most of the basin and the 

northern borderlands receive this same level of sunshine, i.e. 5.6 hours/day, 

but there is an increase southwards to maximum levels of 2600 hours/yr at 

Lakes Mweru and Upemba, while the rest of the southern borderlands 

receive 2300-2500 hours/yr. Relative humidity follows a similar pattern 

to insolation and precipitation, with a large central area astride the equator

having a mean annual RH of over 85 %, decreasing to 80% along the 

northern border and 70-75% on the eastern and southern borders. Only the 

Shaba Plateau in the extreme SE experiences mean annual RH values 

below 70%. 

As might be expected from the foregoing, mean annual temperatures vary 

little over the central parts of Zaire. Most of the country experiences a 

mean annual temperature of 24°C, with an area south of the equator, 

centred on Lake Mai Ndombe, having a mean figure of 25°C. The coastal 

sector is cooler, c. 23°C, the Shaba Plateau cooler still, with mean 

temperatures of 19-20°C, while along the eastern border mean 

temperatures vary with site, falling below 15°C in the mountains locally. 

Mean daily maxima are 30°C over most of the country, falling below this 

in the mountains and on the Shaba Plateau. Mean daily minima are 21°C 

around Lake Mai Ndombe, 20°C in the rest of the western basin, 19°C in 

the eastern half of the basin, 14-15°C on the Shaba Plateau and 12-15°C 

along the eastern border. However, frosts occur on the highest mountains 

where precipitation may be in the form of snow. The snowline is about 

4500 m asl and there is a permanent snowfield at Mt. Stanley. 

Wind velocities are very light over the entire country. Estimated at 2 m 

above ground, mean annual wind velocities are below 3 km/hour in the 

western part of the central basin, and 3-4 km/hour in the eastern half. 

Winds are higher on the borders, with mean annual velocities of 4 km/hour 

along the northern border and 4-5 km/hour in the south. Along the eastern 

border mean annual velocities exceed 6 km/hour. Maximum wind speeds 

recorded at various stations include 28.3 km/hour at Kinshasa (310 m asl), 

25.8 km/hour at Bambesa (621 m asl), 28.5 km/hour at Simana 

(09°37'S/27°01'E - 852 m asl) and 24 km/hour at Rubona 

(02°29'S/29°46'E - 1706 m asp. 

Wetlands 

A number of large lakes lie along the eastern border of Zaire in the trough 

of the Great Rift Valley, which are, from south to north, Lakes Tanganyika, 

Kivu, Edward and Albert. Hard against the eastern border between Lakes 

Kivu and Tanganyika, the valley of the Ruzizi River contains extensive 

wetlands, as does the plain to the south of Lake Edward, and the valley of 

the Semliki River draining Lake Edward to Lake Albert. Wet swampy 

plateaux occur at intervals all along the high watershed immediately to 

the west of the lakes of the Rift Valley system. In the extreme southeast, 

part of Lake Mweru is situated in Zaire, and there is an extensive floodplain 

along the Luapula River to the south of this lake, where that river forms the 

border with Zambia. There are also wetlands associated with the mountains of

the Shaba Plateau to the west. Here are the two principal reservoirs of Zaire, 

Lake Tshangalele, on the Lufira River, over 1000 m asl, and Lake Delcommune, 

where the Lualaba River is dammed. Some 20 substantial lakes occur farther 

downstream on the Lualaba where it traverses the Kamolondo Depression. 

Extensive swamps and floodplain systems occur around Lake Tshangalele and 

the Upemba Lakes. 

Other wetlands occur along the upper courses of the large rivers flowing 

northwards across the southern plateau in Kasai Province, and there are 

innumerable large bogs and swamps in the headwaters of their tributaries. For 

example, in the vicinity of Sandoa (9°41'S/22°56'E), swamps are well 

developed along the Lulua and its tributaries, and wetlands comprise 20-45 % 

of the land surface over very large areas. To the south, in the vicinity of Dibaya 

(6°31'S/22°57'E), a vast block of land exceeding 4000 km 2 , is covered by 

Encephalartos poggei entangled by thickets of the spiny twiner Smilax 

kraussiana. Here, countless gullies containing periodically inundated gallery 

forests are tributary either to the Lulua River, or the Miao and Lukula Rivers 

in the east. From the air the galleries on the dendritic drainage system give the 

landscape the look of alveoli in a lung. Throughout this region the bed of the 

Lulua is broad and sandy, 400-650 m wide, with numerous little islands. 

Having descended from the Shaba Plateau, the Lualaba flows comparatively 

slowly for several hundred kilometres, with accompanying riverine forest and 

some swamps, before descending a waterfall and reaching the 500 m contour 

at Kasongo (4°32'S/26°33'E), and a rapids section and a further waterfall above 

Kindu (3°00'S/25°56'E). North of here the river becomes much wider, 2-3 km in 

places, and descends the 7 cataracts of Boyoma or Stanley Falls 

(0°18'N/25°29'E) before its middle course is deemed to begin and it 

becomes known as the Zaire River. 

In its middle course the Zaire River varies in width between 3-15 km and 

in depth between 3-10 m, and loses only 115 m in altitude over a river 

distance of 1740 km between Boyoma Falls and Malebo Pool (4°1 1 ' 

S/15°35 'E), therefore having a mean gradient of 1:15 000. Over 1500 km of 

this stretch, between Kisangani and Tshumbiri (2°36'S/16°16'E), the river 

itself provides some 1 400 000 ha of very slow flowing open water which has 

many of the characteristics of a lacustrine, rather than a riverine water body. For 

much of this distance it flows in a shallow bed with pronounced levees, around 

almost continuous chains of islands and sand banks, through virtually unbroken 

primary rain forest. The two major tributaries, the Oubangui (Ubangi) and Kasai 

(Casai), which join the river towards the western side of the depression, 

provide a further 680 000 ha of open water and similar riparian environments. 

For distances of 1000 km and 700 km respectively, these two rivers attain 

mean widths of 4 km and are also island studded, although the Kasai is only

markedly so in its lower reaches. Many of the islands are partially or fully 

inundated at periods of high water. Behind the levees, permanent and 

periodically inundated swamp forests extend for distances of up to 35 km on 

either side of the rivers on continuous alluvial tracts. The Oubangui joins the 

Zaire River opposite Lake Tumba, almost on the equator, where land is lowest 

and swamps most extensive. The total area of swamp forest in the central 

Zaire Basin is difficult to assess, because virtually every river, large and small, 

overflows its banks periodically and is accompanied by a tract of poorly 

drained alluvium which supports wetland vegetation. There are at least 12 000 

000 ha of permanently or seasonally inundated forest in the Zairean part of the 

Zaire River Basin, with another 6 500 000 ha on the west bank of the 

Oubangui in Congo, and it is quite possible that the former figure is a 

substantial underestimate. 

All the tributaries of the Zaire River are perennial, and flow in the river is fairly 

constant throughout the year. Mean annual flow rate at Kisangani is 

7000 m 3 /sec, but 41 300 m 3 /sec at Kinshasa, second in volume only to the 

Amazon. A maximum discharge rate of over 65 000 m 3 /sec was recorded in 

1908, and over 75 000 m 3 /sec in 1961, while the record low discharge rate 

was 21 422 m 3 /sec in the exceptionally dry year of 1905. Although the 

equatorial rain belt moves from north to south across the equator, and rain is 

seasonal over the peripheral catchments, the rainy season in the north coincides 

with the dry season in the south and vice versa; thus heavy rain in the 

north tends to compensate for light rain in the south and river flow does not 

change dramatically over the course of a year. Nevertheless, levels in the 

watercourses of the flat central basin normally exhibit two maxima and two 

minima each year. The main peak at both Lake Tumba and Malebo Pool is in 

December-January, coincident with the austral summer rains, followed by a 

minimum in March-April. A second peak occurs in May-June, coinciding 

with the onset of the boreal summer rains, while the lowest levels occur in 

July-September. During the high water periods vast areas of land adjacent to 

rivers in the central basin are flooded. These areas drain during the low water 

periods, which occur twice a year, but the main rivers do not contract 

significantly within their beds. 

Downstream at Tshumbiri the river enters a 220 km stretch known as the Chenal, 

where it is confined by low hills to a narrow channel, 900-1600 m wide, and 

where swamp forest is largely absent. In this section the river deepens to 25- 

30 m, and the current becomes more swift, and it is here that the Kasai enters 

on the south bank. The Chenal ends in Malebo Pool, formerly known as 

Stanley Pool, an almost circular lacustrine expanse of about 52 000 ha 

containing a large central island. 

Other wetlands occur in Bas-Zaire, the province between Kinshasa and the

Atlantic Ocean, which encompasses Malebo Pool and the lower course of the 

Zaire River and several of its tributaries. The wetlands include reed and papyrus 

swamps around Malebo Pool and in the valleys of the Luina and Lunionzo 

Rivers, peat bogs and grass swamps in the valley of the Inkisi River, and 

periodically inundated savannas. The many rivers of the region all support 

forests subject to varying degrees of inundation. The periodically inundated 

sandy banks of rivers, including the Zaire River, support riparian forests along 

tranquil river stretches, with variant types along unstable and stable banks in the 

cataract regions. Pandanus forest occurs along some rivers, even colonising 

parts of the river bed, e.g. that of some tributary streams in the basin of the 

Inkisi River. Immediately behind levees on many streams there are extensive 

riverine swamp forests, subject to alternate flooding and exposure, and 

dominated by Dracaena and Pseudospondias. Other forests, comprising a 

different spectrum of species depending upon edaphic conditions but all 

subject to permanent inundation, are found around Malebo Pool, in 

depressions in the large valley of the Nsele River and in choked valleys on 

schisto-calcareous soils in the Songolo region. Such forests also have a 

scattered occurrence in small depressions throughout Bas-Zaire. 

Other seasonal wetlands, reed, sedge and grass swamps, flooded savannas, and 

riparian and riverine forests, occur on the plateau in the north of the 

country between the Oubangui and Zaire Rivers. 

Flora & Fauna 

Zaire is greater in area than the other five countries of the region combined, and 

judged by mean annual precipitation intensity, which is close to 1700 mm, it is 

among the wettest of countries in Africa. It contains more wetland than any 

other African country and presents a wider range of edaphic, climatic and 

topographical conditions than the other countries of the region, except perhaps 

Cameroon. In consequence there is a greater floristic and faunistic variation 

within each wetland type than is observed in the other countries, apart from 

that which arises simply from differing inundation regimes. In consequence, 

the floras and faunas of the wetlands and lakes are described separately for 

each of the areas or systems discussed below. 

List of Wetlands Described 

1. Wetlands of Bas-Zaire 

2. Wetlands of South Bandundu, Kasai Occidental & Oriental 

3. Wetlands of Shaba Province 

(a) The High Plateau Country

(b) Lake Mweru 

(c) The Luapula Floodplain 

(d) Lake Tshangalele & the Lufira River 

(e) Lake Delcommune 

(f) The Upemba Lakes & the Upper Lualaba River 

4. Wetlands of the Central Zaire Basin 

(a) Riverine Swamps & Forests 

(b) Lake Tumba 

(c) Lake Mai Ndombe 

5. Wetlands of the Eastern Highlands 

6. Lake Tanganyika & the Ruzizi Plain 

(a) Lake Tanganyika 

(b) The Ruzizi Plain 

7. Lake Kivu 

8. Lake Edward 

9. The Semliki River Valley 

10. Lake Albert 

1. Wetlands of Bas-Zaire 

Country: Zaire 

Coordinates: 4°00'-6°00' S/12°20 '-16°00 'E 

Area of Region: c. 65 227 km2 

Altitudinal Range: 0-1000 m asl 

General: The Atlantic coast of Zaire is generally of high relief, with cliffs 

along much of its length. Miniature mangrove stands occur where these are 

breached by little coastal streams, e.g. at the mouth of the Creek de 

Mosquitos, just north of Banana (5°58'S/ 12°27'E). A short southward 

facing promontory extends from Banana into the mouth of the Zaire River, 

sheltering two large, and numerous small, islands in bays on the north 

shore of the estuary. The islands extend more than 90 km up estuary, past 

the town of Boma (5°50'S/13°03'E), and are separated from the mainland 

by broad channels. However, the main stream and channel of the river 

pass south of the islands, and tidal (mangrove) forests fringe all the 

channels between the islands and the mainland. They occur in narrow 

strips, 100-500 m wide, for 30 km up both the `Crique de Banana' and the 

`Crique des Pirates', and are again well developed at Chango Creek 30 

km farther upstream. They also cover many sand or mud banks which are 

emergent at low tide, but are best developed on mainland shores where

small streams enter the estuary. Spring tidal amplitude is 1.7 m at the 

mouth, 1.5 m at Quissanga, 0.85 m at Mateba and 0.08 m at Boma near 

where the estuarine section ends and to where mangroves extend. 

Cliffs rise to 244 m asl on the north bank of the river near Matadi, and 

upstream of this place, 150 km from the ocean, the first torrential section 

is encountered, extending for some 60 km between Yellala Falls and 

Isingila Falls, with many rapids. From here, in proceeding farther 

upstream, the river is generally more tranquil, although deep, with a 

strong current, and confined to a narrow bed for nearly 170 km. Although 

there are turbulent patches the second major torrential section is not 

encountered until Manyanga Falls, from where it extends for another 55 

km upstream to the vicinity of Sanga. Above Sanga, the river is less 

turbulent, but still deep, confined to a narrow bed and swift flowing, until 

Malebo Pool is reached after a further 75 km. 

The Pool is 25 km wide and 35 km long, occupying a depression encircled 

at a distance by hills rising to 500 m asl, while the water level in the Pool 

is close to 300 m asl. The area of the Pool is about 50 000 ha and the 

central part is occupied by M'Bamou Island (18 000 ha), which is 

Congolese territory. There are several groups of small islands, and a little 

archipelago in the channel on the south side of M'Bamou Island, opposite 

the mouth of the Nsele River, which discharges into the pool. These 

islands are Zairean territory and are entirely submerged at high water. 

The southern shore of the pool is swampy for 30 km between the mouths 

of the Ndjili and Nsele Rivers, with swamps extending 7 km inland at the 

western side near the Ndjili. Counting the islands, some 10 800 ha of 

swampland occurs in Zaire on the southern side of the pool. The Nsele is 

the largest river entering Malebo Pool and swamps extend back up its valley 

for 22.5 km, with a mean width of 2 km, and then farther upstream, 

another stretch, some 1.6 km wide, extends for 70 km along the river, 

totalling some 16 800 ha. The current in the pool is variable but averages 

5 km/hr. The pool is shallow with depths of 3-10 m, while water levels 

vary by as much as 3 m over the course of a year. 

Climate: The estuary mouth is comparatively arid receiving only 800 mm 

rain/yr, while the town of Banana receives a mere 740 mm, but mean annual 

rainfall increases upstream to 900 mm at Boma, 1023 mm at Matadi and 1374 

mm at Kinshasa where the dry season has a duration of about 120 days. The hills 

on either side of the river are wetter than the river valley, receiving 1400 mm 

on the border with Cabinda, 1498 mm at MbanzaNgungu (5°17'S/14°51'E) 

on the south side, and nearly 1600 mm over the upper valley of the Nsele 

River on the Angolan border. The mean annual temperature at Banana is 

25.2°C, while the absolute maximum recorded is 33.6°C and the absolute

minimum 15°C. Corresponding figures for Matadi are 23.5, 35.4 and 15.2°C, 

while for Kinshasa at the eastern end of the region on the banks of Malebo 

Pool they are 23.3, 33.3 and 13.2°C. In the hills to the south of the river, at 

Mbanza-Ngungu, they are 23.1, 37.5 and 9.8°C. Malebo Pool experiences 

1650-1700 hours of sunshine each year, with monthly figures of 120-150 

hours. During the dry season the wind at Malebo Pool is consistently from 

W or SW, but it is more variable during the wet season. 

Water Quality: Poll (1959) quotes the water temperatures at Malebo Pool in 

September 1957 as being 27.3°C at the surface and 27.4°C at 3 m depth, 

when the air temperature was 26.8°C. The water is turbid with Secchi 

depths of about 50 cm. It is analysed monthly at Kinshasa and the mean 

figures for the year 1976-77, in mg/1, were calcium 2.23; magnesium 

0.86; sodium 1.99; potassium 1.33; bicarbonate 7.11; sulphate 2.0; chloride 

2.71 and silicate 9.7. The waters are comparatively well oxygenated. In 

1957 Poll obtained a reading of 5.45 mg 0/1. 

Wetland Flora 

Tidal Forests: The tidal forests are dominated by Rhizophora racemosa 

in the frontal swamp and by R. harrisonii and R. mangle in the middle 

zones, the first two species reaching heights of 25-30 m locally. Avicennia 

africana also occurs in these mangrove swamps, frequently associated 

with Laguncularia racemosa, and on the landward margins, with 

Conocarpus erecta. Avicennia occupies some sandy seaward sites near 

the mouth of the estuary, and occurs along the back of the swamp, behind 

the Rhizophora forest, in downstream sites where the transition to 

terrestrial vegetation is saline and fairly dry. Other species commonly 

associated with Avicennia along the landward fringe of the mangrove are 

Caesalpinia bonduc, Chrysobalanus icaco, Dalbergia ecastaphyllum, 

Drepanocarpus lunatus, Hibiscus tiliaceus, Ternstroemia africana 

and Ximenia americana. In upstream sites, and especially where small 

tributary streams enter the estuary through the mangrove, the Rhizophora 

forest grades into fresh water swamp forests, many of which are weakly 

tidal. These are dominated by Pandanus candelabrum and/or Raphia 

vinifera, the latter often in association with Phoenix reclinata and the 

spiny climbing palms Ancistrophyllum secundifolium and Eremospatha 

haullevilleana, which render the vegetation impenetrable. Raphia 

swamps, or raphiales', frequently occur in mosaic with other types of 

swamp forest throughout Bas-Zaire. 

Riparian Associations: Forests subject to semi-permanent inundation 

occur behind the raphiales along the Zaire Estuary, on almost level banks 

which slope imperceptibly into the river. These same forests occur on the

Zaire River in placid sites upstream, and also on some of the larger 

tributaries. Floristically they are usually dominated by Mitragyna 

stipulosa, but are quite diverse, containing such associate species as 

Acioa dewevrei, Alstonia congensis, Anthonotha pynaerti, Baikiaea 

insignis, Blighia welwitschii, Brazzeia congoensis, Bridelia ripicola, 

Dialium pachyphyllunt, Dichaetanthera africana, D. strigosa, 

Eriocoelunz microspermunz, Guibourtia demeusei, Mallotus oppositifolius, 

Nauclea diderrichii, N. pobeguinii, Oubanguia africana, Parinari glabra, 

Sterculia bequaertii, Symphonia globulifera, Uapaca heudelotii, 

Voacanga thouarsii and Uvariodendron mayumbense. There is often an 

understorey of coarse herbs, among which Marantochloa mannii and M. 

hensii are important. 

A type of swampy gallery forest, subject to less permanent inundation, is found 

on rivers in deep valleys cut into impermeable polymorphic sandstones in the 

hills south of the river. Here, Syzygium gilletii and S. guineense ssp. 

huillense are the dominant trees, generally accompanied by Anthocleista 

liebrechtsiana, Bertiera laurentii, Coelocaryon botryoides, Dichaetanthera 

corymbosa, Gaertnera leucothyrsa, Quassia undulata, Raphia sese, 

Uapaca guineensis and Xylopia rubescens. Ancistrophyllum 

secundifiorum, Eremospatha cabrae and E. haullevilleana are common 

climbing palms in this forest, while in the understorey Impatiens kasaiensis 

is perhaps the commonest plant. Numerous ferns and selaginellas grow low 

down on the tree trunks. 

Although, above tidal limits, water levels in the Zaire River do not fluctuate 

greatly, those of the tributaries in Bas-Zaire have markedly seasonal flows, 

because they are short rivers and the local climate has a pronounced dry season 

during the austral winter. They rise in the local hills, but in the case of the 

Inkisi, far south in Angola. On these rivers gallery forests may be deeply 

inundated for half the year and dry for the other half. Floristically they are 

characterised by the abundance of Dracaena capitulifera and 

Pseudospondias microcarpa, with Berlinia bracteosa, B. bruneelii, 

Cleistopholis patens, Lannea welwitschii, Mallotus oppositifolius, Mimosa 

pigra, Symphonia globulifera, Treculia africana and Uvariodendron 

mayumbense as common associates. 

Pandanus butayei occurs in almost monospecific stands along some minor 

streams in the Inkisi Basin to the southwest of Madimba (5°00'S/15°08'E). 

The pandans grow on the stream banks, and where flow rates are not 

vigorous, possibly even petering out at times during the dry season, they may be 

seen to have invaded the stream beds, the water flowing through their stilt roots, 

and around the outside of clumps.

Where small rivers form pools with muddy banks, and along tranquil 

stretches of the Zaire River, especially on muddy backwaters, there may be 

a dense bushy pioneer association. This grows on flat banks, in shallow 

waters or on muddy soil, and is characterised by the dominance of 

Alchornea cordtfolia and Anthocleista liebrechtsiana, with the presence of 

other species including Aeschynomene cf. elaphroxylon, Clappertonia 

ficifolia, Mimosa pigra, Phyllanthus reticulatus and Sesbania sesban. In 

deeper water Cyperus papyrus becomes dominant and large stands occur 

around Malebo Pool, in the Nsele Valley, and in many small choked valleys of 

the Luina and Lunionzo Basins. In these latter places, landslips or other local 

disturbances have led to drainage from the lower parts of valleys being impeded. 

The papyrus and Alchornea associations may abut and even intricate with each 

other. 

By contrast, sparse herbaceous vegetation occurs on young sand banks and 

unstable sandy river banks. Various short sedges occur in these situations, 

together with Artanema longifoliunz, Cassytha filiformis, Eleusine indica, 

Eragrostis atrovirens, Glinus oppositifolius, Grangea maderaspatana, 

Mitracarpus scaber, Portulacafoliosa and Scoparia dulcis. Most are of 

wide distribution, pantropical or palaeotropical, and penetrate far upstream 

into the central Zaire Basin. Where soil is more stable and subject only to the 

weakest currents, Phragmites mauritianus beds develop, or rarely, swards of 

Pennisetum nodiflorum. 

In the swift flowing and cataract ridden section of the Zaire River between 

Matadi and Kinshasa, other low thickets develop in sites subject to frequent 

but short periods of inundation. Here Manilkara lacera and Pachystela 

breviceps are the most characteristic species. They are usually found with 

some or all of the following: Baphia verschuerenii, Dalbergia louisii, 

Deinbollia laurifolia, Eugenia dewevrei, Garcinia spp., Guibourtia 

demeusei, Ochtocosmus congolensis, Phyllanthus reticulatus, 

Schotia bequaertii, Strychnos spp., Synsepalum dulcificum and Xylopia 

parviflora. Climbers are abundant in this kind of forest, especially 

Agelaea dewevrei, Artabotrys pynaertii, Calycobolus klaineanus, 

Memycylon spp., Popowia littoralis, P. oliverana, Pouchetia 

africana, P. gilletii, Salacia elegans, Uvaria dacrernontii and 

Uvariopsis congensis. These thickets are often very dense. 

In the cataract regions, rocks subject to alternate inundation and exposure, and 

the walls of cascades subject to constant spray, are dominated by bryophytes, 

with some specialised higher plants belonging to Podostemaceae and 

Lentibulariaceae. Perhaps the most characteristic of these are 

Inversiodicraea tenuissima and Utricularia andongensis.

Where the banks of the Zaire River are sandy but stable, with a high water 

table but seldom deeply inundated, the riverine forest has a closed canopy 

up to 25 m high, composed almost exclusively of Irvingia smithii and 

Parinari congensis. Frequently this type of forest succeeds the foregoing 

type. Among the occasional associates are Allophyllus africana, 

Chrysobalanus atacorensis, Dialium excelsum, Guibourtia demeusei, 

Trichilia retusa and Uapaca heudelotii. The Araceous climber and 

creeper, Culcasia scandens is frequently abundant, both on the soil and on 

the boles of the trees. Some woody lianes also occur in this forest type. 

Mostly they are common to the Manilkara thickets described above, and 

possibly persist from a preceding seral stage. 

The edges of quiet lakes and pools, formed for example in abandoned river 

channels in the lower valleys of some of the tributaries, are often fringed by 

stands of Polygonum senegalense in a transition from aquatic to terrestrial 

vegetation. The open waters support carpets of Nymphaea caerulea, N. lotus 

and Nymphoides indica, with Aponogeton subconjugatus, and Trapa 

natans var. bispinosa. These species are also common in front of 

Phragmites and papyrus in some swamps, for example on Malebo Pool. 

Ceratophyllum demersum and Utricularia spp. are common submerged 

associates. In other places, on acid peaty soils, the margins of small 

oligotrophic pools are dominated by Eleocharis acutangula. These pools 

are common in the upper parts of some tributary valleys. Numerous species 

of Utricularia are present in the water, and in the most shallow places 

Sphagnum and Xyris spp. Calm forest pools are often covered by Lemna 

paucicosta, Pistia stratiotes and Salvinia nymphellula. Eichhornia 

crassipes and Salvinia auriculata have become naturalised on some 

ponds and rivers. At times floating meadows of the former species have 

been known to completely obstruct the channel of the Bundi River near its 

confluence with the Zaire River, and it also forms vast carpets in the swamps 

bordering Malebo Pool. 

Floodplains occur behind the papyrus swamps on the southern shore of 

Malebo Pool and also in the valleys of the Ndjili and Nsele Rivers. Here 

typical species which, although rooted, contribute to vast floating prairies, 

are Echinochloa pyramidalis, E. stagnina, Ipomoea aquatica, Neptunia 

prostrata, Oryza barthii and Vossia cuspidata. 

Non-Riverine Wetlands: Sedge/grass swamps occupy swampy 

depressions on schisto-calcaerous soils, where surface water is almost 

permanent. The most common species in these sites is undoubtedly 

Echinochloa pyramidalis, but others which accompany it include 

Clappertonia ficifolia, Cyrtosperma senegalensis, Eulophia angolensis, 

Jardinea congoensis, Loudetia flammida, Phragmites mauritianus and

Polygonum salicifolium. Other depressions in savanna regions are 

covered by almost pure swards of Setaria anceps, with species of 

Bulbostylis, Cyperus and Scleria as the most common associates. 

A complex of peat bogs and flat peaty swamps occurs in the upper parts 

of some river valleys, but are best developed in the eastern parts of the 

Inkisi Valley on schists and Kalahari sands. Usually these bogs form a 

mosaic with the acid pools containing Eleocharis acutangula described 

above. They are characterised by an abundance of Rhynchospora 

candida, but with diverse groupings in the ground layer. Here Sphagnum 

spp. and various Eriocaulaceae and Xyridaceae are most common. The 

species with the highest fidelity are Mesanthemum radicans, 

Paspalanthus lamarckii, Xyris hildebrantii, X. sphaerocephala and X. 

vanderystii. Drosera madagascariensis, Microchloa kunthii, Panicum 

parviflorum, Paspalum comnzersonii, Utricularia arenaria, U. 

spiralis and U. subulata grow on the elevated hummocks of Sphagnum, 

increasing the diversity of the mosaic. Occasionally the wettest parts of 

these bogs are invaded by Andropogon virgatum and in many sites a 

graminaceous stratum develops. This is, however, generally composed of 

Leersia hexandra, Rhytachne rottboellioides, Sacciolepis africana, 

Setaria anceps and Trichopteryx dregeana, with a substantial admixture 

of Bulbostylis laniceps, Cyperus halpan (= C. haspan) and C. 

laxispicatus. 

Some circular depresssions on the plain of Lukunda are inundated for the 

greater part of the year, and are covered by a type of swamp forest 

dominated virtually exclusively by Irvingia smithii, with Holarrhena 

floribunda and Pseudospondias microcarpa as uncommon associates. 

The sparse understorey comprises Grewia seretii, together with 

Cleistopholis patens, Glyphaea brevis and Memecylon spp. 

Wetland Fauna 

Fishes: The fish fauna below Boma has many euryhaline species, e.g. 

pristids, elopids, sphyraenids and migulids, together with freshwater 

representatives of predominantly marine families, such as clupeids, 

gobiids, tetraodonts and the mangrove mudskippers Periophthalnius spp., 

and a number of secondary freshwater cichlids and cyprinodonts. 

Thereafter the rapids sections provide what are probably the largest expanses 

of torrential water in the tropics, and here many fish species exhibit special 

adaptations to fast flowing, dark, well oxygenated water, and are able to 

spend much of their lives under rocks. Examples are Gymnallabes 

tihoni, a clariid catfish, Caecomastacenzbalus brichardi, the cichlids 

Leptotilapia rouxi and L tinanti, also the blind cave fish, Caecobarbus

geertsi (Cyprinidae), and species of Atopochilus, Chiloglanis, 

Euchilichthys, Garra, Labeo, Steatocranus and Teleogranzma. 

Adaptations to torrential water are however, not confined to the lower 

Zaire River. They are found again, involving different species, in the rapids 

sections of many streams tributary to the upper sections of the river. 

Some 235 species of fish have been described from Malebo Pool, of 

which 5 are sometimes said to be endemic to the pool. The Mormyridae, with 

36 species in 4 genera, are better represented in Malebo Pool than any other 

family, both in terms of numbers of individuals and numbers of species. 

Important mormyrid species are Gnathognemus greshoffi and Mormyrops 

deliciosus. Among clupeids, Microthrissa royauxii and Poecilothrissa 

congica are important, while characids include species of Alestes, Bryconaethiops 

and Hydrocynus goliath and H. vittatus. Barbus pleuropholis 

and Leptocypris modestus are common cyprinids, and Chrysichthys 

crantchii and Gephyroglanis longipinnis are important bottom dwellers. 

The lungfishes, Protopterus aethiopicus and P. dolloi, inhabit the 

swamplands, together with Phractolemus ansorgei and several species of 

Clarias, Micralestes, Synodontis and Tetraodon. 

Amphibia: The swamps throughout Bas-Zaire support large and diverse 

amphibian populations, with many species of frogs and toads. 

Reptiles: Among the aquatic or semi-aquatic reptiles are Antyda sp., 

Boulengerina annulata, Crocodylus cataphractus, C. niloticus, Naja 

melanoleuca, Pelontedusa sp., Pelusios sp., Psammophis sibilans, Python 

sebae and Varanus niloticus, while Dasypeltis fasciata, Dendroaspis 

janiesonii, Philothamnus semivariegatus and Thelotornis kirtlandii are 

arboreal in swamp and gallery forests. 

Birds: The avifauna of the swamps, rivers, lakes, swamp forests and palm 

swamps is rich and comprises several hundred species, many of which are 

found throughout the central Zaire River Basin. Widespread species, including 

migrants, include Acrocephalus arundinaceus, A. schoenobaenus, Actitis 

hypoleucos, Anas spp., Anastomus lamelligerus, Anhinga rufa, Apus 

apus, Ardea melanocephala, A. purpurea, Ardeola ralloides, Bias 

musicus, Botaurus stellaris, Butorides striatus, Callidris nzinuta, Ceryle 

rudis, Chlidonias leucoptera, Corythornis cristata, Egretta intermedia, 

Ephippiorhynchus senegalensis, Gallinago media, Glareola nordmanni, 

Haliaeetus vocifer, Halcyon leucocephala, Hieraaetus spilogaster, 

Hirundo rustica, Ixobrychus minutus, Lanius collurio, L. minor, Larus 

fizscus, Megaceryle maxima, Merops apiaster, Motacillaflava, Muscicapa 

striata, Nycticorax nycticorax, Pandion haliaetus, Phalacrocorax africanus, 

P. carbo, Phylloscopus trochilus, Riparia riparia, Rynchops flavirostris

and Tringa glareola. 

Mammals: Among the mammals Hippopotamus amphibius is rare, having 

virtually disappeared from Malebo Pool, but Aonyx congica, Atilax 

paludinosus, Dasymys bentleyae, Lutra maculicollis, Potamochoerus porcus 

and Tragelaphus spekei are common. Several monkeys live in the gallery 

forests, palm swamps and seasonally inundated forests of Bas-Zaire, e.g. 

Cercocebus torquatus, Cercopithecus aethiops cynosurus, C. ascanius 

(south of the Zaire River), Cercopithecus cephus, Colobus polykomos 

angolensis and Miopithecus talapoin, the latter pair occasionally found in the 

mangroves. 

Human Impact & Utilisation: Two large cities are situated on the edges 

of Malebo Pool, Brazzaville in Congo, with a population of 300 000, and 

Kinshasa in Zaire, with a population of 3 500 000. Both towns are important 

ports, serving centres upstream, and over a million tons of merchandise pass 

through them each year. Human influence on Malebo Pool is therefore quite 

pronounced, and the local fishery lands catches of 1500-2000 tonnes/yr. 

Further, and particularly in Zaire, most of the land escaping annual inundation 

has been cleared for agriculture or horticulture, but there has been comparatively 

little destruction of the swamps. Away from the cities, towns and 

villages have grown up on the edges of floodplains, and the seasonally 

flooded areas are utilised in various ways during the dry season, and are 

fished during the wet. In the estuarine section, both Boma and Matadi are 

ports, Boma serving the north shore and Matadi, which is linked to Kinshasa 

by rail, serving the south. The mouth of the estuary is sparsely populated. Inland, 

while most forest types in Bas-Zaire have suffered serious depradations, 

swamp forests have largely escaped, since they have, until very recently, 

been deemed valueless. Now some clearing is being undertaken for rice 

production. 

Conservation Status: A small area of the Mayumbe Massif in Bas-Zaire 

north of the Zaire River, approximately 5°35'S/13°10'E, and containing the 

headwater areas of the Luki River, is protected in the Luki Forest Reserve. 

However, little wetland is found here, and much of the forest in the reserve is 

of secondary character. Total protection for the forest has been in operation 

since 1963, when all felling ceased. Hunting and fishing are also prohibited. 

2. Wetlands of South Bandundu, Kasai Occidental & Oriental 


Coordinates: 4°15 ' -8°00'S/16°00 ' -26°00 'E 


Altitudinal Range: 450-1150 m asl

General: All parts of this region experience a dry season of 100-130 days 

duration, and a rainfall of between 1400-1750 mm/yr. There is a double 

periodicity over most of the region. December and March are the wettest 

months, when respective falls of 200250 mm and 180-230mm are received. 

Mean monthly temperatures are in the region of 23°C, rising to 24-25°C in the 

wet season. Daily temperature range is greater in the dry season than the wet, 

with mean maxima and minima close to 32 and 15°C in July, while the 

corresponding figures for December are 29 and 19°C. Absolute maxima at 

most stations are in the region of 37°C and absolute minima in some southern 

stations is below 9°C. 

The area is drained by many rivers and their innumerable tributaries, all 

eventually flowing in parallel, northwards off the southern plateau. The 

largest of these are, from west to east, the Kwango (Cuango), Kwilu 

(Cuilo), Loange, Kasai, Lulua, Kelagne Bushimaie, Lubilash and Lomami 

Rivers, but between the Kwango and Kwilu alone, there are no less than 9 

major streams, the Wamba, Bakal i, Konzi, Inzia, Luie, Lukula, Kafi, Gobari 

and Kwenge Rivers. All except the Lomami eventually discharge into the 

Kasai, which, north of the area presently under consideration, swings 

westwards and skirts the southern border of the central Zaire depression. The 

individual swamps in this geographic region are too numerous to be described 

in detail. Periodically or permanently inundated lands follow the lowest parts of 

all the river valleys, in strips 100 m to 10 km wide. There are for example 11 

major swamps, totalling some 155 000 ha, on the Kwilu River and its 

tributaries between 6-7°S, together with many minor swamps, and there is no 

less than 450 000 ha of wetland in the vicinity of Sandoa (9°41'S/22°56'E) 

associated principally with the drainage basin of the Lulua River at altitudes 

of 750-1050 m asl. 

Wetland Flora 

The region is characterised by extensive savanna plains with gallery forests 

along the rivers, but with more extensive valley bottom forests towards the 

central Zaire depression. The savannas are dominated by a Julbernardia- 

Brachystegia association in the south, reaching latitudes of 7°20'S in places, 

but farther north this gives way to other associations, e.g. a Tristachya 

nodiglumis-Diectomis fastigiata association in the west, and an 

Encephalartos poggei-Smilax kraussiana association in the east. Large 

blocks of pseudo-steppe vegetation interdigitate with these, characterised by 

Aristida vanderystii and Boophane disticha. Most of the valley bottom forests 

are periodically inundated, but some, in depressions, are inundated almost 

permanently. Numerous grass, reed and papyrus swamps occur in the upper 

valleys, with extensive peat bogs in some choked valleys, and in very shallow 

depressions on plateau areas. There are also substantial areas of hygrophilic

grassland. 

Riparian & Floodplain Associations: In southern Bandundu, sandy banks in 

and along major rivers, subject to periods of inundation by quite swiftly 

flowing water, are colonised by a woody Malouetia bequaertiana- 

Uapaca heudelotii association, forming dense thickets adjacent to the 

water. The principal associates are Berlinia giorgii, Cathormion 

altissiina, C. obliquifoliolata, Dioclea reflexa, Homalium ealaense, 

Irvingia sniithii, Mucuna flagellipes, Opilia sparsiflora, Syzygium 

guineense and Uvariopsis congensis. Here are to be found a number of 

epiphytes, including Ancystrorhynchus clandestinus, Angraecum 

distichum, Asplenium africanum, Calyptrochilunz emarginaturn and 

Platyceriunz stemaria. Elsewhere, Alchornea cordifolia is the pioneering 

woody species. 

Along the banks of the big rivers, north of the parallel 5°S, one encounters 

outliers of floodplain forests dominated by Lannea welwitschii, 

Monopetalanthus pterydophyllus, Pseudospondias microcarpa, 

Rauvolfia mannii and Thomandersia laurifolia. They occur on alluvium 

and are found to intercalate with the association previously described, and a 

Gilbertiodendron dewevrei association, which dominates the valley sides 

and extends down onto the fringes of the floodplain. 

The lowest parts of valley floors in this region are occupied by swamp forests 

and several distinct types can be recognised. Wide galleries of swamp forest 

occur along rivers in broad valleys on impermeable polymorphic 

sandstones, which ensure that the soil surfaces are permanently 

waterlogged. The most characteristic species are Newtonia devredii and 

Uapaca guineensis. These forests are primitive in character and provide a 

refuge for several Guinean species, the distribution of which was 

significantly constricted during the Quarternary. Some other species 

commonly found in these galleries are Acioa dewevrei, A. lujae, Berlinia 

grandiflora, B. sapinii, Dacryodes edulis, Dalbergia louisii, Epinetrum 

villosum, Eriocoelum microspermum, E. petiolare, Homaliunz inolle, 

Mitragyna stipulosa, Monopetalanthus pteridophyllus, 

Paramacrolobium coeruleum, Pararistolochia promissa, Parinari 

glabra and Symphonia globulifera, together with species of Anthonotha, 

Chrysophyllum, Culucasia, Dialium, Lonchitis and Nephrolepis. 

In ravines and deep narrow valleys, swamp forests cling to the courses of 

streams and are dominated by Mitragyna stipulosa with Sarcophryniurn 

schweinfurthianum a feature of the ground layer. Sterculia bequaertii and 

Symphonia globulifera are the principal associates. At the heads of broad 

trough-like valleys swamp forests are dominated by Xylopia rubescens, with

several species of Syzygium. The flanks of these forests tend to comprise 

Syzygium cordaturn and S. parvifolium in narrow girdling belts, while in 

the interior Syzygium giorgii is the typical associate. On the banks of swift 

flowing rivers, subject to sudden high floods, Pandanus butayei sometimes 

forms long monospecific stands. However, in the upper reaches of the 

Kwango River, where the river is deeply entrenched in the vicinity of Swa 

Tende (7°14'S/17°07'E), below the two waterfalls of Kasondo-Lumda and 

Guillaume, Raphia laurentii (= R monbuttorum) swamps cover the valley 

floor. 

Along the sandy courses of lower reaches of the eastern rivers in Kasai, e.g. 

the Lulua and Sankuru Rivers, the banks subject to frequent inundation and rapid 

changes in water level are colonised by woodland in belts several kilometres 

wide. Here the lower stratum is discontinuous and poorly developed and there 

are scattered patches of herbs. The spectrum of species differs from that in 

the west of the region and typically includes Acioa lujae, Alsodeiopsis 

poggei, Baikiaea insignis, Berlinia sapinii, Cathormion altissimum, 

Cynometra pedicellata, Gilletiodendron inildbraedii, Gouania 

africana, Hexalobus crispiflorus, Irvingia smithii, Morelia senegalensis, 

Ouratea arnoldiana, Tessmannia dewildemaniana, Uapaca heudelotii 

and Uvariopsis congensis, with the lianes Oxymitra sayauxii and 

Pleioceras gilletii. In the herbaceous stratum one finds Dracaena poggei and 

Hypolytrum heterophyllum. 

In depressions away from rivers on floodplains, on the land behind levees, 

and in wet valley heads, sandy lithosols are frequently colonised by a well 

stratified swamp forest attaining 20 m in height. This contains a range of 

species, but is given special character by the presence in its canopy of an 

abundance of Syzygium guineense ssp. guineense and Voacanga thouarsii. 

The forest is heliophilic, generally has a second stratum at a height of 10-15 

m, a bushy layer at 2-5 m, and a ground layer up to 1.5 m high. In addition to 

the two species already cited, the most characteristic trees of the upper strata 

are Ficus congensis, Gardenia imperialis, Mitragyna stipulosa, and 

locally Elaeis guineensis. In the lower strata, Adenostemma viscosum, 

Costus lucanusianus, Cyclosorus striates, Nephrolepis biserrata 

(growing terrestrially), Orestias foliosa and Scleria racemosa are 

common. Adenia dinklagei (Passifloraceae) and Culcasia scandens 

(Araceae) are bole climbers, while Pleopeltis scolopendria grows 

epiphytically. Upstream this woody association frequently gives way to an 

herbaceous swamp dominated by the hygrophilous grasses Loudetia 

phragmitoides and Trichopteryx dregeana, which may extend to the very 

head of the valley. 

The woody vegetation just described tends to be succeeded by a climax

swamp forest, with a canopy exceeding 30 m in height and providing up to 

90% cover, with a lower arborescent stratum at 15-20 m. An abundance of 

Coelocaryon botryoides and Uapaca guineensis typify this forest, but other 

co-dominants include Alstonia congensis, Baikiaea insignis, Eriocoelunz 

microspermum, Macaranga saccifera, Mitragyna stipulosa, Parkia 

filicoidea, Raphia spp., Rothnzannia megalostigma, Strombosiopsis 

tetrandra, Symphonia globulifera and Treculia africana. Climbing palms, 

Ancistrophyllum and Eremospatha spp. also reach the canopy. 

Pauridiantha pyramidata dominates the understorey, but is associated 

with Ataenidia conferta, Cyrtosperrna senegalense, Dicellandra barteri, 

Marantochloa congensis, Menzecylort myrianthum, Napoleana 

imperialis, Sarcophrynium schweinfurthianum and Xylopia acutiflora. 

Anthoclitandra robustior, Atroxima congolana, Cercestis congoensis, 

Microsorium punctatum, Milletia gossweilleri and Popowia bicornis grow 

either as climbers or epiphytes, together with those species mentioned in this 

context in the preceding paragraph. This type of forest occupies the sites in 

gallery forests where the soils are permanently waterlogged. The narrowness 

of most valleys limits the extent of this forest type, which is seldom great. 

Hygrophilous evergreen forests, dominated by Gilbertiodendron dewevrei, 

occur on alluvial flats which may be waterlogged for much of the year, but 

flooded only briefly. These forests attain heights of 20-30 m and are generally 

well stratified. While Gilbertiodendron comprises the canopy layer almost 

exclusively, it has associates in the upper strata, notably Alphanocalyx 

cynometroides, Garcinia smeathmannii and Monopetalanthus microphyllus. 

Occasionally relict species from swamp forest may be present, indicating 

that the area once supported this type of vegetation. Perhaps the most common of 

the relict species are Asystasia vogeliana, Dicranolepis oligantha, 

Eremospatha haullevilleana, Palisota thyrsiflora and Raphia spp. Among 

lianes, Agelaea dewevrei, Anthoclitandra robustior, Jaundea pubescens and 

Landolphia foretiana are most abundant. 

Elsewhere, e.g. in the vicinity of Mweka (4°51'S/21°34'E), hygrophilous semideciduous 

forests occupy this same habitat, with an abundance of Autranella 

congolensis, Cynometra hankei, Julbernardia seretii and Scorodophloeus 

zenkeri, and the two forest types may intergrade. 

Where periodically inundated swamp forest has been cleared by man in the more 

elevated regions, between 6-8°S, and has not been able to regenerate, it tends to 

be replaced by a Loudetia phragmitoides grassland, containing 

characteristically the labiate, Briquetastrum africanum. This latter 

association occurs in the west, between the Kwango and Kwenge Rivers, but 

is especially common in Kasai Oriental, to the NE of Dibaya, where the 

landscape is highly dissected. The association comprises only herbs and

suffrutescent species. In addition to the two species already cited, the following 

are important: Acriulus grigiifolius , Aeschynomene sensitiva, Andropogon 

tenuiberbe, Crassocephalum picridifolium, Crotalaria sessilis, 

Cyclosorus striatus, Cyperus auriconzus, C. distans, C. latifolius, 

C. laxispicatus, Desmodium Dissotis princeps, Eriochrysis 

brachypogon, Eulophia latilabris, Fimbristylis miliacea, Fuirena 

umbellata, Hydrolea guineensis, Hyparrhenia bracteata, Hypogynium 

spathiflorum, Kotschya stolonifera, Kyllinga pungens, Otometria 

elatior, Panicum nervatum, Rhynchospora candida, R. corymbosa, 

Scleria melanomphala, Selaginella congoensis, Trichopteryx dregeana 

and Vigna nigrita. This marshy association is generally bounded by a 

monospecific band of Loudetia simplex, 10-20 m wide. 

Shady backwaters along rivers and ponds in swampy riverine forests support a 

Lemna paucicosta-Pistia stratiotes association. Many rivers, e.g. much of 

the Kwango, are fringed along the waters edge by meadows of Echinochloa 

pyramidalis with an abundance of Polygonum senegalense. A variety of 

vegetational types occur on hydromorphic soils in broad sandstone valleys, 

especially above some of the waterfalls where the river water spreads in a thin 

sheet over a large area. In places the waterlogged soils extend in flat belts, 2-3 

km wide, along the rivers, and here the several associations are determined 

primarily by edaphic factors. Where there is often a sheet of free water at the 

surface, Aeschynomene fulgida is common in association with Craterostigma 

goetzii, Dissotis debilis, Emelia sp., Fuirena unzbellata, Heteranthoecia 

guineensis, Leersia hexandra, Rhytachne rottboellioides, Sacciolepis 

typhura, Sphagnum planifolium, Stipularia africana, Utricularia spp., 

Trichopteryx dregeana, Xyris hildebrandtii and X. imitatrix. 

On sandy rivers those parts of shallow banks which are periodically 

submerged are colonised by dense beds of Rhynchospora candida, 

together with Axonopus compressus, Drosera sp., Eriochrysis 

brachypogon, Mesanthemum radicans, Paepalanthus poggeanus, 

Sphagnum planifolium, and species of Torenia, Utricularia and Xyris. In 

adjacent situations lawns develop on superficially swampy sites, being 

characterised by the presence of Craterostigma latibracteatum and 

Neurotheca longidens, together with Andropogon huillensis, Eragrostis 

plurigluma, Melinis macrochaeta and Panicum lindleyanunz. In river 

valleys, where the sheet of groundwater remains close to the surface 

throughout the dry season, Dissotis thollonii and various sedges 

predominate. 

Non-Riverine Wetlands: An association of very wide distribution 

throughout the region under consideration is distinguished by the 

presence of Loudetia vanderystii. It occurs on a range of hydromorphic

soils, away from the immediate vicinity of rivers, but its precise floristic 

composition depends upon water levels, the duration of the dry season, 

local edaphic and climatic conditions and geographic location. Among the 

many species found in this type of vegetation the following are 

representative: Andropogon huillensis, Aristida atroviolacaea, Ascolepis 

protea, Bulbostylis pumila, Commelina umbellata, Crotalaria 

glauca, C. sessilis, Cyperus lanceolata, C. serpens, C. tenax, 

Elyonurus brazzae, Eragrostis racemosa, Fimbristylis dichotoma, F. 

umbellata, Gladiolus nzelleri, Glinus oppositifolius, Helichrysum 

alismatifolium, Hypogynium spathifolium, Kyllinga erecta, Panicum 

braz.zavillense, P. ianthum, Polygala claessensii, P. ukirensis, Pycreus 

scaettae, Rhytachne rottboellioides, Scleria hirtella, Schizachyrium 

mukulense, Setaria restioides, Sporobolus barbigerus and the 

arborescent Syzygium guineense ssp. huillense. In places Xyridaceae 

are dominant with Xyris hildebrandtii, X. inzitatrix, X. sanguinea and 

X. vanderystii well represented. In the wettest sites Eriocaulaceae are 

prominent, e.g. Synognanthus poggeanus and S. walbergii. This 

vegetation often has two strata, an upper one 100-150 cm high and a 

lower one 30-40 cm high, with occasional clumps of trees. Generally this 

association is confined to alluvial deposits of white oligotrophic sands, in 

which, as the level of the water table varies from season to season, the 

upper layers are subject to alternate periods of anoxia and aeration. 

Surface waters may at times reach depths of 20-40 cm. 

In southern Bandundu the waters of ponds on the granite massifs support 

an Azolla pinnata association. Other ponds, open to higher insolation, are 

covered by Nynzphaea spp., and are fringed by Cyperus papyrus with 

low growing Cyclosorus striatus and Vossia cuspidata in the water at 

the bases of the culms. Permanent swamps of this latter type are well 

developed in the Tungila Valley. 

Wetland Fauna 

The fish faunas of the rivers and swamps are strongly affiliated to those 

of the central Zaire Basin, but since the rivers of the region under 

consideration here all have rapids or waterfalls, and are all tributary to the 

Kasai which enters the Zaire River in the Chenal section, the faunas of their 

upper reaches differ from that of the middle Zaire River. Most subsystems of 

the Kasai are thought to have high proportions of endemic species, 

although only a few have been investigated in any depth. However, of 60 

species described from the upper Kasai River, 19 are endemic (Poll, 

1963). The presence of Zambezian fish in the Kasai system suggests that 

at some point in its history the river, or one of its tributaries, captured the 

headwaters of a stream which once flowed into the Zambezi. Many of the

Kasai rivers share a watershed with the Zambezi and its tributaries. 

Aplocheilichthys and Hypsopanchax are genera confined to rivers 

flowing through savanna country, while Aphyosemion and Epiplatys (all 

Cyprinodontidae) are genera found in the lower reaches of rivers 

traversing tropical rain forest. 

Frogs and toads are abundant throughout the wetlands. The reptile and 

bird faunas of this region are similar to those described in section 1, Bas- 

Zaire. Mammals present in the swamp and gallery forests are Aonyx 

congica, Atilax paludinosus, Cephalophus monticola, C. sylvicultor, 

Cercocebus aterrimus, Cercopithecus aethiops cynosurus, C. ascanius, 

C. mona pyrogaster, C. neglectus, Colobus polykomos, Dasymys sp., 

Funisciurus pyrrhopus, Galago demidovii, Hippopotamus amphibius, 

Leptailurus serval, Miopithecus talapoin, Nandinia binotata, Pan paniscus 

(pygmy chimpanzee), Pellomys fallax, Potamochoerus porcus, 

Potamogale velox, Sylvicapra grimmia, Syncerus caffer, Tragelaphus 

scriptus and T spekei. 

Human Impact & Utilisation: Much primary forest has been disturbed, 

having been exploited by the indigenous people traditionally, and since the 

middle of this century by Europeans. The Europeans exported huge 

quantities of timber during the second world war, subsequent to which 

intensive exploitation has continued along the railway line from the port 

of Ilebo on the Kasai River, to Kananga, Kamina, Bukama and 

Lubumbashi. In this region some wet forested areas cut through a long time 

ago have been reduced to a Carapa procera woodland with an understorey 

of Ananas sativa. 

Conservation Status: Unprotected. 

3. Wetlands of Shaba Province 


Coordinates: 8°00'-13°30'S/22°00'-29°40'E 



General: Shaba is situated in the extreme SE of Zaire where much of the 

land is over 1000 m, and several elevated blocks rise to over 1500 m asl. 

The largest of these are the Plateau of Manika and the Kundelungu 

Mountains, both oriented SW-NE and roughly parallel to each other. On 

either side of these highlands, and between them, are large swampy 

depressions. Lake Mweru and the Luapula Floodplain lie to the east of 

the Kundelungu Range, the headwater swamps of the Lufira River lie 

between the highland blocks, and the Upemba lake system lies to the west

of the Manika Plateau in the Kamolondo Depression. The border with 

Zambia and then Angola follows a watershed eastwards across the south 

of Shaba Province, and for most of the way, is very wet and swampy. 

(a) The High Plateau Country 


General: Above 1000 m, the valleys of most streams carry dambo or 

dembo vegetation in their uppermost reaches, sometimes with central 

strips of low forest along the watercourses. Along the southern border the 

commonest tree in these strips is Acacia caffra var. campylacantha, and 

downstream broad galleries of this species replace the dembo vegetation. 

Here the periodically flooded forest may reach widths of several 

kilometres, but frequently within it there are expanses of open water 

along the stream bed, covered by Nymphaea spp., or there may be 

extensive stands of Typha domingensis, or mixed stands of short sedges, 

Cyperus papyrus swamps, reedbeds of Phragmites mauritianus or aquatic 

meadows dominated by Leersia hexandra and Echinochloa stagnina. The 

Muniama River near Lubumbashi provides a good example of such a 

valley floor, occluded by Acacia caffra forest, but with broad central herb 

swamps. On other watercourses herbaceous swamps completely dominate 

the valley floors, and arborescent vegetation is only poorly developed, e.g. 

on the Kafuba and Kisanga Rivers, also near Lubumbashi, in an area where 

wetlands account for more than 6% of the land surface. 

The deeply dissected highland block to the west of the Kamolondo 

Depression, centred on Kamina (8°46'S/25°00'E), where the Lubilash, 

Lumembe, Lomami and Lovoi Rivers rise, is covered by dry savanna 

forest, with gallery forest along the rivers. Pandanus candelabrum forms 

depleted galleries near Tshibonde and Mwadi-Kayembe, but forests 

dominated by Canarium schweinfurthii with an understorey of Mellera 

lobulata (Acanthaceae) occur along watercourses in the deeper valleys, 

while Mitragyna stipulosa and Spondianthus preussii are predominant in 

the broader ones. Grassy floodplains occur where inundation is deep and 

prolonged, and in these places the watercourses frequently carry a 

Pandanus candelabrum-Thalia welwitschii-Floscopa glomerata 

association. This may be followed on higher ground by a Pennisetum 

purpureum zone, or a Cyperus latifolius-Rhynchospora triflora zone, and 

these in turn by Loudetia kagerensis-Fimbristylis gabonica zones. 

Patches of Centratherum englereanum (Compositae) and 

Hyparrhenia bracteata also occur in the least deeply flooded areas. 

Highland bog pools, such as are found on the Manika and Kundelungu 

Mountain plateaux, contain Drosera madagascariensis, Nyphaea

sulphureus, Utricularia spp., and are fringed by various sedges. Montane 

stream sides are often lined by thin beds of Phragmites mauritianus, 

while Psychotria mushiticola is a common stream side tree at altitudes 

above 1400 m. 

The Kundelungu National Park, an integral nature reserve, protects the 

southern plateau of the Kundelungu Mountains, the 400 m escarpment by 

which they fall to the Lufira Valley, and a narrow strip of valley floor 

beneath the escarpment. On the plateau various pools and areas of bog are 

protected, and the courses of some minor streams, tributary to the Lufira 

River, are protected together with their gallery woodlands. 

(b) Lake Mweru 


Coordinates: 8°29 ' -9°28 'S/28°23' -29°10'E 

Area: c. 200 000 ha open water in Zaire 

Altitude: 919 m asl 

Nearest Towns: Pweto (at N end lake); Lubumbashi (280 km SW) 

General: Lake Mweru is an almost rectangular lake, 120 km long and 48 

km wide, situated in SE Zaire, on the border with Zambia, at the end of the 

broad Luapula Floodplain. The national boundary crosses the lake from 

SW-NE and approximately half of the open water surface is in Zaire. The 

lake is quite shallow, increasing in depth from south to north. Over the 

southern half the mean depth is 3 m, while in the northern half it is 10 m, 

with a maximum recorded depth of 37 m. The lake contains several 

islands but the principal ones are Zambian territory. About 155 km of 

shoreline is situated in Zaire, on the western and southern sides of the lake. 

The western shoreline is steep, with low cliffs broken by scattered bays, 

but the southern and southwestern shores are flat and swampy, and dip 

very gently into the lake. The lake is filled by the Luapula River and 

several lesser streams which enter the lake in this region, and is drained by 

the Luvua River, which leaves the lake immediately SW of Pweto. 

Climate: Mean annual rainfall over the lake is 1020-1120 mm depending 

upon site, but higher in the catchments. December is the wettest month, 

with falls of up to 275 mm, and the rainy season persists for about 195 

days. Mean annual temperature at the lake is 22-23°C depending upon site. 

October is the warmest month with mean daily maxima of 31-34°C and 

mean daily minima of 18-19°C. July is the coolest month with a mean 

temperature of 20°C and mean daily maxima and minima of 28°C and 

14°C. Sunshine receipts are in the region of 2600 hours/yr, with a 

monthly maximum of 310 hours in July and a minimum of 125 hours in 

December. Incident radiation approximates 170 Kcal/cm 2 /yr on the

lake and evaporation from the lake surface has been estimated as 1700 

mm/yr. 

Hydrology & Water Quality: The drainage basin, for which Lake 

Mweru forms a collecting point, is vast, up to 500 km wide and 550 km 

long with a total area of some 200 000 km 2 . The waters of the lower 

Luapula are high from March to May, and low between September and 

January. A maximum flood level of 8 m has been recorded at Kasenga 

(10°22'S/28°45'E), but the mean maximum level is 3.8 m at this point. 

The waters of the lake itself are high from April until July, reaching their 

lowest between October and February. The mean annual fluctuation is 1.5 

m, but a maximum variation of 4.7 m has been recorded. Water leaving 

the lake via the Luvua, enters the Lualaba and eventually the Zaire River 

en route to the Atlantic Ocean. 

The lake is polymictic. Surface water temperatures reach 25-30°C during 

October-May, but fall to 22-25°C during June-September. Secchi depths 

vary from 0.6-1.46 m, and total dissolved solids amount to 41-69 mg/1 

depending upon the season. The pH of lakewater varies between 7.0-9.3, 

while in the swamps it is 6.0-6.9. The lake is well oxygenated, the surface 

waters containing 5.4-8.9 mg 0/1 depending upon the season. 

Wetland Flora: Hydrophytes in the lake include Azolla pinnata, 

Ceratophyllum denzersum, Lagarosiphon ilicifolius, Najas pectinata, 

Nymphaea caerulea, N. lotus, Pistia stratiotes, Potanzogeton spp., 

Ottelia spp., Utricularia spp., and Vallisneria aethiopica. Beds of aquatic 

grasses, including Echinochloa spp., Leersia hexandra and Vossia 

cuspidata, occupy the lowest levels of the seasonally inundated zone around 

the lakeside, and are backed by Cyperus papyrus in sites along the 

southwestern shore, with Phragmites mauritianus and Typha domingensis 

as typical associates. Rocky shores are dominated by Chlorophyceae, with 

some hygrophilous herbs at higher levels, including species of 

Alternanthera, Ipomoea and Oldenlandia. 

Wetland Fauna: The fish fauna of the system is diverse. 146 species 

have been described from the system, 94 from Lake Mweru. There are 

numerous representatives of Characidae, Cichlidae, Clariidae, Cyprinidae 

and Mormyridae. Oreochromis macrochir is the most important 

economic species in Lake Mweru, the adult fishes living a pelagic life 

mainly in the deeper waters of the northern part of the lake, while the 

juveniles tend to be confined to bays and swamps in the south where they 

shelter among the floating vegetation, especially Vossia. The adults migrate 

south to spawn from August-September, and remain in the area until 

January-February. Other species important to the fishery are Labeo

altivelis, which migrates up rivers to spawn, and Alestes macrophthalmus, 

which seems to comprise two populations, one which spawns in swiftly 

flowing waters of the Kalungwishi River (in Zambia) and one which 

spawns in Lake Mweru itself. 

Amphibia are abundant, and reptiles in Lake Mweru include two species 

of crocodiles, Crocodylus cataphractus and C. niloticus, which are both 

considered vulnerable, and the aquatic snake Boulengerina annulata. 

Man-eating crocodiles are a problem on parts of the southern lakeshore. 

The avifauna of the lake and its environs is rich. Very many of the typical 

Central African wetland species occur here, including most of those listed 

in section 1, Bas-Zaire, together with Actophiloritis africana, Ardea 

goliath, Balaeniceps rex, Dendrocygna viduata, Musciscapa aquatica, 

Pelecanus onocrotalus, Phoeniconaias minor, Phoenicopterus ruber, 

Ploceus pelzelni and Porzana pulsilla obscura. Acrocephalus 

schoenobaenus, Chlidonias leucoptera and Larus fuscus are palearctic 

migrants. 

Hippopotamus amphibius is found in the southern parts of the lake, while 

several small mammals, e.g. Atilax paludinosus and Lutra maculicollis 

are more widely distributed. 

Human Impact & Utilisation: The lake waters are fished from both 

Zambian and Zairean sides, the catches being exported to Copperbelt 

towns in Zaire, to the SW of the lake. 


(c) The Luapula Floodplain 



Area: c. 330 000 ha 

Altitude: 919-980 m asl 

Nearest Towns: Kasenga (on upper floodplain); Lubumbashi (190 km 

SW) 

General: The Luapula Floodplain begins at Chembe (12°00'S) where the 

river descends below the 1000 m contour. The floodplain is oriented due 

N-S and extends for almost 300 km along a section where the river forms 

the border with Zambia. However, for the first 180 km from Chembe to 

Kasenga (10°22'S/28°45'E), it is confined by a narrow valley. Peak water 

level rises of 8 m have been measured at Kasenga, with a mean annual rise 

of 3.8 m, but from here north the floodplain widens, and in places a wetland

extends 46 km west of the river on the Zairean side of the border. The 

floodplain includes several peripheral lakes and numerous riverside 

lagoons, and substantial areas of permanent swamp. These latter fringe 

some of the lakes and lagoons, occupy abandoned river channels and 

extend back as riparian swamps along several tributaries flowing east from 

the Kundelungu Mountains to the Luapula. The most important 

tributaries are the Lutsipushka and Kalala Rivers, the former with 46 km of 

riparian swampland. The largest of the lakes is almost circular with a diameter 

of 7 km, and three others are more than 5 km long. 

Wetland Flora: Papyrus swamps fringe lagoons along the Luapula and 

dominate large areas of permanent swampland, with the typical associate 

species Phragmites mauritianus and Typha domingensis, and the aquatic 

grasses Echinochloa stagnina and Vossia cuspidata. Other tall grasses 

found in the swamps include Miscanthidium violaceum and Pennisetum 

purpureum. Wetland herbs found in the swamps in shallow water, and in 

rafts of floating vegetation, include Cyperus imbricatus, Ethulia 

conyzoides, Ludwigia leptocarpa, Melanthera scandens and Polygonunz 

senegalense. The most important floodplain grasses are Oryza barthii, 

which occupies the most deeply flooded sites, and Echinochloa pyranzidalis 

and Sacciolepis africana on less deeply inundated sites. The peripheral 

areas, where inundation is less than 40 cm and which are only briefly flooded, 

carry many graminaceous species, including Acrocerus macrum, 

Heteropogon contortus, Hyparrhenia spp., and Vetiveria nigritana, with 

Loudetia simplex and Themeda triandra on the very margins. Little 

groves of Aeschynomene elaphroxylon occur on isolated and elevated 

sandy patches along the river, and often these are accompanied around their 

outer, lower, margins by Hibiscus diversifolius which may be deeply 

inundated at high water. Patches of swamp forest typical of the interface 

between the Guineo-Congolean region and the Zambezian region, 

comprising Aporrhiza nitida, Ficus congensis, Garcinia smeathmannii, 

Syzygium spp., Uapaca guineensis and Xylopia spp. occur in some 

permanently wet sites along rivers and streams. Gallery forests containing 

Chlorophora excelsa, Khaya nyasica and Parkia filicoidea occupy 

river banks subject only to shallow and very temporary inundation upstream. 

Brachystegia-Julbernardia woodland covers much of the surrounding, 

unflooded country, on sandy-loam soils, but within this woodland there are 

numerous large dambos, often containing patches of mushitu, i.e. swampy 

evergreen forest. 

Wetland Fauna: The fish fauna of the Luapula between Lakes Mweru and 

Bangweulu has both Zambezian and Zairean affinities. It is an isolated fauna, 

being cut off from the Zambezi system by the watersheds along the 

Zambia/Zaire border, and from the Upper Lualaba River by two sets of rapids

and a dam on the Luvua River below Lake Mweru. Of 120 species so far 

identified, 33 are endemic to the Luapula system (Poll, 1963). The lungfish, 

Protopterus annectens brieni, occurs in the associated riverine swamps 

and floodplains, together with Nothobranchius taeniopygus. Many species of 

fish from Lake Mweru migrate up the Luapula to spawn. 

Frog populations in the swamps reach prodigious sizes, the animals falling 

prey to a variety of fish, snakes and birds. Reptiles found in the system 

include the snakes 

Natriciteres olivacea, Naja melanoleuca, Philothamnus irregularis, 

Psaminophis sibilans and Python sebae. Arboreal species in the swamp 

and gallery forest are Dispholidus typus, Dasypeltis scabra, Philothamnus 

semivariegatus, Thelotornis kirtlandii and possibly Dendroaspis 

angusticeps. The water monitor, Varanus exanthematicus angolensis, 

occurs in the swamps, and there are two terrapins, Pelomedusa subrufra and 

Pelusios subniger. The avifauna is typical of that found in association with 

floodplains, lakes and reedbeds, and is very similar to that of Lake Mweru. 

Hippopotamus amphibius and Kobus leche leche occur in the swamps of 

the lower floodplain. Other species visiting the area are Alcelaphus 

lichtensteini, Hippotragus equinus, H. niger, Kobus ellipsiprymnus, K. 

vardoni, Taurotragus oryx, Tragelaphus scriptus, while Loxodonta 

africana, Redunca arundinum and Syncerus caffer are found in the 

swampy regions along the rivers. Cercopithecus ascanius katangae and 

C. mitis opisthostictus are arboreal species in the riparian forests, while 

Potamochoerus porcus and Phacochoerus aethiopicus frequent the 

fringing woodland. Among small mammals, Aonyx capensis, Atilax 

paludinosus, Lutra maculicollis, and the rodents Dasymys incomtus, 

Pellonzys fallax and Thryonomys swinderianus occur in the swamps. 

Human Impact & Utilization: The area is virtually undeveloped, but 

some 150 000 persons live in the region. There is no mining nor 

manufacturing, and tourism has not yet developed. Outside the small and 

widely separated towns there are few villages. Small scale agriculture 

takes place on the floodplains, with cassava, millet, maize, groundnuts 

and sweet potatoes the chief crops. Fishing is locally intensive along the 

lower Luapula and catches have exceeded 5000 tonnes/yr. A substantial 

proportion of the annual catch is sent south to the railway and copperbelt 

towns. The bulk of the catch comprises Oreochromis macrochir, with 

some Serranochrontis and Tylochromis spp., and much smaller 

quantities of Alestes, Auschenoglanis, Clarias, Gnathognemus and 

Synodontis. A motor boat service for passengers and cargo operates with 

a fortnightly schedule between Kasenga, nearly 150 km upriver, and 

Pweto at the northern end of Lake Mweru.


(d) Lake Tshangalele & the Lufira River 


Coordinates: 9°00-13°13'S/26°40'-27°57'E 

Area: c. 400 000 ha (total wetland in system) 


Nearest Towns: Likasi (20 km W); Lubumbashi (80 kin S) 

General: The Lufira River has two sources (11°34'S/26°29'E and 

11°52'S/26°52'E) to the west of Lubumbashi (Elizabethville), in both 

places rising in swampy areas. It flows from the headwater confluence, 

again flanked by a series of swamps, north to Lake Tshangalele (10°45 '- 

11°00' S/26°56'-27°16'E), one of the two major reservoirs in Shaba. 

Thereafter it flows north, receiving, at a point 10°30'S/27°30'E on the 

right bank near Kienge, a major tributary which also drains a swampy 

valley. Then the Lufira meanders NW across the floor of a large triangular 

depression, which has its apex at Kienge, and its base oriented SW-NE 

along the escarpment of the Manika Plateau. The triangular depression is 

160 km wide at the base, and 130 km long from base to apex, thus having 

an area close to 10 400 km 2 . Much of this area is of low relief. Numerous 

tributary streams flow down from the Kundelungu Mountains which form 

the eastern side of the triangle, while 3 major tributaries cross the broadest 

part of the depression parallel to the Manika Escarpment, having 

confluences just above the Lufira Rapids (9°31'S/27°02'E). From here, 

close to the base of the triangle, the Lufira has cut a much steeper sided 

valley through the Manika Plateau whence it flows to a junction with the 

Lualaba River 20 km north of Lake Upemba. 

Lake Tshangalele is roughly rectangular in shape, some 25 km long and 15 

km wide, with a narrow arm (5x15 km) pointing NE, from the tip of which it 

drains. It has an open water area of approximately 36 250 ha, approximately 

1000 m asl. The area of wetland in the valleys of the Lufira and its tributaries 

north of Lake Tshangalele probably exceeds 350 000 ha. 

Wetlands accompany the Lufira almost all the way from Kienge to the 

Lualaba, a distance of 275 km in a straight line, but possibly 440 km along 

river. Riparian reed and papyrus swamps, and flooded gallery forest, occupy 

sections of the river banks. The river and its swamps are largely confined to the 

eastern side of the triangular depression, along the line of the Kundelungu 

Mountains, but wetlands also spread along the base of the triangle, 

adjacent to the Manika Escarpment, along the courses of tributaries, such as 

the Dikuluwe. Towards the confluence of these two streams, several deeply

inundated areas of up to 3600 ha, lie away from the rivers, with less 

deeply inundated land closer. A chain of almost 100 recent oxbow lakes, 

situated to the west of the Dikuluwe River, indicates a former course. 

Another cluster north of the Lufira, below the confluence of the two 

streams, indicates that that river too has recently changed its course on the 

flat valley floor. Some of the lakes are 15-18 km long and 200 m wide, 

while others are just 200 m long and 50 m wide. Tracts of inundated land 

reach 17 km in width across the Lufira in places, and up to 9 km across 

the Dikuluwe. Where the Lufira traverses the narrow pass through the 

highlands of the Manika Plateau, swamps are much less extensive, but 

they expand again on the far side of the gorge, in the Upemba region. 

Wetland Flora & Fauna: The flora and fauna of the Lufira system is 

similar to that of the Upper Lualaba/Upemba Lake System dealt with in 

section 3e. 

Human Impact & Utilisation: There are fishing villages along the 

Lufira Floodplain, cattle are grazed in the region, and there is small scale 

agriculture. Fires often burn into the wetlands in the dry season. 

Conservation Status: Unprotected, except for the lower part of the 

Lufira River immediately above its confluence with the Lualaba. 

(e) Lake Del Commune 


Coordinates: 10°27 ' -10°55 ' S/25°24 ' -25°51'E 

Area: c. 60 000 ha 

Altitude: c. 1100 m as1 

Nearest Towns: Kolwezi (23 km W); Lubumbashi (200 km SE) 

General: The Lualaba (Zaire) River rises at a point approximately 

11°52'S/26°25'E close to the Zambian border, and incidently, some way 

south of the source of the Zambezi, 240 km to the WNW. The Lualaba at 

first flows WNW, parallel to the border, before swinging north to enter the 

impoundment of Lake Delcommune. Some land along the river is swampy, 

also land along the border which follows the watershed between the Zaire 

and Zambezi Basins. Then, other swamps occur around parts of Lake 

Delcommune, the area having been a wetland prior to impoundment. 

Wetland Flora & Fauna: The lake has become an important site for 

aquatic birds and has been stocked with fish. A large proportion of the 

species described for the Upemba Lake System (next section) are present. 

The borderland swamps are mostly grass and sedge filled dambos, draining 

sluggishly to small streams, which may support swamps containing bushy

species along their courses, once they have become entrenched in distinct 

valleys. The riverine swamps are dominated by Phragmites mauritianus and 

its typical associates, but Cyperus papyrus occurs in the valley. Floodplain 

grasses similar to those described for the Luapula are also present, and there is 

some gallery forest, also of composition similar to that on the Luapula. 

Human Impact & Utilisation: The lake is artificial and its creation 

destroyed most of an existing wetland. 

Conservation Status: The lake and its immediate environs are afforded a 

degree of protection as a Natural Water Reserve. 

(f) The Upemba Lakes & The Upper Lualaba River 


Coordinates: 4°00-10°00 ' S/25°20 ' -28°45 'E 

Area: c. 1 444 000 ha (total wetland on Lualaba System in 

region) 


Nearest Towns: Kibombo (at N end); Bukama (at S end) 

The Upemba Lakes: This section deals with wetlands on the Lualaba 

River between Lake Delcommune and Kibombo (4°00'S), a straight line 

distance of 750 km. Some 40 km after leaving Lake Delcommune the 

Lualaba enters the broad trough-like Kamolondo Depression, a graben, 100 

km wide and 400 km long, oriented SW-NE, between the Manika Plateau on 

the east and the Hakansson Mountains on the west. The highlands of the Manika 

Plateau reach 1889 m asl, but the Hakansson Mountains attain heights of just 

over 1200 m asl. The floor of the trough is 1000 m asl at its SW end, and 

slopes down quite abruptly to 610 m, at which point it flattens and the 

Upemba Lakes and Marshes begin. The Upemba System comprises about 

50 shallow lakes, the principal ones being, from south to north, Lakes 

Kabwe, Kabele, Sangwe, Tungwe, Malenda, Upemba, Kisale, Niangwe, 

Zimbambo, Kibala and Kabamba. These lakes extend along the trough for 225 

km, in a belt up to 55 km wide, with a mean width of 37 km. They are set in 

a continuous belt of swamps, and are filled by the overflowing of the river, 

which winds through the swamps and between the lakes, communicating 

with the majority through shallow channels which are often hidden by the 

dense vegetation. However, it flows through Lakes Kabwe and Kisale, 

which are thus expansions of the main river bed. In total there are about 800 

000 ha of wetland in the trough, and a further 79 000 ha immediately to the 

west on the Lululwe, Kilubi and Lovoi Rivers, between 8°-9°S and 24°50'- 

25°40'E. These latter swamps are typical riparian swamps which follow the 

rivers in belts up to 7 km wide for distances of up to 60 km. These swamps 

drain into the Lualaba via the Lovoi River, which reaches a confluence

etween Lakes Kisale and Zimbambo. According to Welcomme (1979) the 

permanently inundated part of the Kamolondo Depression extends to about 

704 000 ha, while in the wet season the flood covers about 1 184 000 ha. 

Lake Upemba is the largest of the lakes, situated between 8°32'-8°49'S/26°13'- 

26°30'E. It has maximum open water dimensions of 40x20 km, and some 53 

000 ha of open water in contracted state. However, the lake basin is over 70 

km long, the northern half being practically occluded by vegetation. In profile 

the basin is very shallow, with a maximum measured depth of 3.2 m in 

November, at the end of the dry season. The bottom is covered by soft black 

mud and much plant debris. 

The Upper Lualaba: Having left the Upemba lakes, the Lualaba, after a few 

kilometres, again enters a swampy belt extending 80 km along the river, with 

another cluster of small lakes between 6°55'-7°15'S, the largest of these being 

Lakes Kittongola and Towe. The river flows almost due north in this sector, 

and indeed does so all the way to Kongolo (5°20'S/27°00'E), traversing a very 

flat plateau and picking up two important tributaries on the east bank en route. 

These are the Luvua River which drains Lake Mweru and the Bangweulu 

System, and the Lukuga River which drains Lake Tanganyika. The river then 

loses height in traversing two sets of rapids below Kangolo, and then receives 

the Luama River on the east bank, before veering northwest to reach Kibombo 

on the parallel 4°S. Here, extending many kilometres northwards, the west bank 

is again swampy. Altogether 14 major tributaries enter the Lualaba between Lake 

Kabamba and Kibombo, but those of the east bank are more important in terms 

of volumetric discharge, rising as they do in the very wet mountains along the 

eastern border. 

Another extensive wetland system occurs in the headwater regions of the 

Luama River. This stream has 5 sources in the mountains, two rising at altitudes 

over 2000 m. The river descends 3 waterfalls and several minor rapids in its 

lower course, but upstream of Pene Mende (4°18'S/28°11'E), it drains a flat 

swampy valley, the head of which bifurcates, with a branch leading NE. A 

tributary, coming down this much narrower valley, drains valley floor swamps 

right back to its source near Fizi (4°18'S/28°56'E). In their entirety, the Luama 

Swamps accompany the river and its tributaries for 130 km and comprise 

about 60 000 ha of wetland. 

Climate: Mean annual rainfall over the Upemba Lakes is 1000 mm, with 

December the wettest month, when falls are in the vicinity of 170-180 mm. 

The dry season lasts for 155-165 days. Mean incident radiation is 166 

Kcal/cm 2 /yr, and the system enjoys 2400-2500 hours sunshine/yr, with July 

the sunniest month (c. 395 hours) and January the most overcast month (c. 

130 hours). Mean annual temperature is 24.4°C; the September mean is

27°C, with mean monthly maxima and minima of 36 and 19°C, and the 

corresponding June figures are 23, 33 and 14°C. Rainfall increases 

progressively along the Lualaba, north of the Kamolondo Depression, reaching 

1400 mm in the vicinity of Kasongo (4°30'S) and 1700 mm at Kindu (3°00'S). 

Between this point and Kisangani, where the middle course of the Zaire River 

begins, the Lualaba flows due north through a very wet zone, where over 2000 

mm of rain falls each year and there is no distinct dry season. 

Hydrology & Water Quality: In the Upemba System, the waters of the 

Lualaba are high from February-April and low from August-October. The mean 

fluctuation in water level at Bukama, at the southern end of the system is 2.8 

m, with minimum depths of 3 m and maximum depths of 5.8 m. At Maka the 

change in level is only 1.1 m over the course of a year, with a low level of 1.9 

m and a maximum of 3 in. Lake Upemba is high from March-June and low 

from October-January. The depression is exorheic and drains from the north via 

the Lualaba. 

The waters of the Upemba Lakes are warm with mean surface 

temperatures close to 23°C in July and 33°C in November. The lakes are 

polymictic and even bottom temperatures reach 31°C in November. The pH 

range is 6.4-8.0 and the waters may be brown, or yellowy-green in colour. 

Wetland Flora: The Upemba Lake/Swamp system presents vistas of tall 

herbaceous swamps, dominated either by Cyperus papyrus or by Typha 

domingensis, but with Pycreus mundtii and Paspalidium geminatum 

common on the sides of water courses. All these species line the Lualaba 

River and the numerous lakes, and huge rotting floating mats of Cyperus 

papyrus, some of which reach 10-15 ha in extent, may detach from the banks 

and begin to drift on the lakes. This species has, among its lower growing 

aquatic associates, Cyclosorus striatus, Impatiens cf. kasaiensis, Ipomoea 

aquatica, Panicum repens, Polygonunz salicifolium and Vossia cuspidata, 

and these may all be found on or in the rafts. Other small rafts are found to 

be composed of Pycreus and Paspalidium. Little patches of swamp 

woodland, comprising almost exclusively Aeschynomene elaphroxylon and 

Hibiscus diversifolius, occur on abandoned levees and other elevated 

sandy sites, which are inundated to depths of 40-60 cm at high water. These 

support a dense avifauna and are often whitened by the guano of roosting birds. 

The open waters may become covered by waterlilies, Nymphaea caerulea, 

N. lotus and Nymphoides indica, together with Lemna sp., Pistia 

stratiotes and Trapa ratans. 

As the Lualaba flows north the surrounding savannas become more dense 

until eventually the canopy closes and rises, so that hundreds of kilometres 

before the river crosses the equator it is enclosed by high equatorial rain 

forest. The deciduous, and then evergreen gallery forests of the savanna

zones become progressively less distinct, physiognomically if not 

floristically, as finally the galleries merge with the rain forest. The river 

broadens and its banks become sandier, and the forest front along the river 

is festooned with lianes. The flora of the riverine forest in this most 

northerly part of the region is similar to that described in the next section, 

Wetlands of the Central Zaire Basin. 

Wetland Fauna: The fish fauna of the upper Lualaba comprises 141 species, 

among the most noteworthy of which are the two lungfishes Protopterus 

aethiopicus congicus and P. annectens brieni, several species of 

Polypterus (P. birchir katangae, P. endlicheri congicus, P. ornatipinnis 

and P. senegalus meridionalis), and Ctenopoma ctenotis, Ichthyborus 

besse, Oreochromis upembae and Tetraodon mbu. According to Poll 

(1976) 14 species are endemic to the Upemba system. A number of Upemba 

species spawn near the sand beaches at low water when they suffer intense 

predation, e.g. Clarias sp., Labeo annectens, Oreochromis niloticus 

upembae, Synodontis notatus and S. pleurops. 

The frog and toad populations in the Upemba district are prodigious. Over 40 

amphibians have been recognised in the Upemba National Park, 34 of which 

are known to occur in the wetlands. Some species are reputed to be endemic 

to the Kamolondo Depression, e.g. Afrixalus fulvovittatus upembae (a reed 

frog) and Phrynobatrachus cryptotis. Hemiscus wittei is common. 

Crocodylus cataphractus is quite abundant but C. niloticus is less so. The 

water monitors Varanus exanthematicus and V. niloticus are both present, as 

are several terrapins. Other aquatic or semi-aquatic reptiles include 

Amphisbaena quadrifrons capensis, Aparallactus capensis 

punctolineatus, Boulengerina annulata, Dromophis lineatus, Monopeltis 

scalper gerardi, Natriciteres olivacea, Naja melanoleuca, Philothamnus 

irregularis, Psammophis olivacea and Python sebae. Among the arboreal 

species of gallery forests Dasypeltis scabra, Philothamnus 

semivariegatus and Thelotornis kirtlandii are most common. 

The avifauna of the wetlands is very similar to that of the Bangweulu 

Basin in Zambia, and to the Lake Mweru/Luapula Floodplain fauna. It 

includes most of the widespread species listed in section 1, Bas-Zaire, 

together with Actophilornis africana, Ardea goliath, Balaeniceps rex, 

Butorides rufiventris, Dendrocygna viduata, Grus carunculatus, Larus 

cirrocephalus, Limnocoraxflavirostra, Muscicapa aquatica, Pelecanus 

rufescens, Plectropterus gambensis, Ploceus pelzelni, Porphyrula alleni 

and Sarkidiornis melanotos. Palaearctic migrants include Acrocephalus 

schoenobaenus, Chlidonias leucoptera, Larus fuscus, Motacilla flava, 

Riparia riparia and Sterna hirundo.

Mammals associated with wetlands throughout this particular region 

include Aonyx capensis, Atilax paludinosus, Cercopithecus mitis 

opisthostictus, Dasymys incomtus, Hippopotamus amphibius, Kobus 

ellipsiprymnus, K. leche, Leptailurus serval, Loxodonta africana, 

Potamochoerus porcus, Potamogale velox and Syncerus caffer. Other 

species are particularly associated with the papyrus and Typha swamps, 

e.g. Pellomys fallax, Tragelaphus spekei and Thryonomys swinderianus, 

while yet others frequent the gallery forests of the Lualaba and its 

tributaries. Among these the following can be cited: Cephalophus 

monticola, C. sylvicultor, Cercocebus aterrimus, Colobus badius foal, 

C. polykomos prigoginei, Felis aurata, Galago demidovii, Nandinia 

binotata, Pan paniscus and Tragelaphus scriptus. 

Human Impact & Utilisation: The southern part of the region is 

comparatively densely populated. The large towns of Lubumbashi, Likasi, 

Tenke, Kolwezi, Lubudi and Bukama are strung out from SE to NW across 

the southern end of the region, but the populations of these centres exert 

little influence on the wetlands immediately to the north, except that of 

Bukama at the southern end of the Upemba System. Within the 

Kamolondo Depression population density increases from south to north, 

but the only centre is Malemba-Nkulu, in the region of which there were 

175 388 inhabitants in 1975. There are neither manufacturing industries 

nor tourism. Fishing villages occur along the Lufira, and around the 

northern, unprotected lakes of parts of the Upemba System. Fishing in the 

depression is locally intense. The total catch for 1957 was in excess of 22 

000 tonnes, but the figure has declined since then. Nevertheless, the 15 424 

tonnes catch of 1981 was the lowest for some years. The area is the chief 

fish producing centre for Shaba and most of the annual catch is exported to 

the afore-mentioned towns, or to Kasai. The commercial fishing centres 

are Maka, Kialo, Nyonga, Kalombe, Kikondja, Masango, Malemba- 

Nkulu, Kabala, and Mulongo. 

The Lualaba River is navigable between Bukama and Kongolo, a 

distance of some 650 km, but in 1938 the railway line between Kongolo 

and Kabalo was opened, and since then regular commercial river traffic 

has terminated at Kabalo. Before 1956 the annual cargo haul downstream 

was 60 000-80 000 tonnes, while coming upstream, it was about 50 000 

tonnes, with about 8000 passengers being carried in each direction. In 1956 

a rail link was inaugurated between Kabalo and Kamina (107 km NW of 

Bukama), after which river transport rapidly diminished in importance, 

but there is still traffic between Malemba-Nkulu, in the centre of the 

Upemba System, and Kabalo. In the southern part of the Upemba System, 

Bukama and Malembo-Nkulu, the maintenance of a navigable channel

through the papyrus has been virtually abandoned. In the dry season 

burning of peripheral wetland areas, in the Kamolondo Depression and 

Lufira Valley, often causes fires in the wetlands. 

Conservation Status: About half of the Upemba Lake System, comprising 

all the local biotypes, is totally protected in the Upemba National Park, 

established as an integral nature reserve. The protected area includes 

Lakes Kabwe, Kabele, Sangwe, Malenda, Tungwe, Upemba and Kisale, 

and 180 km of the Lufira River, upstream from its confluence and 

through the gorge in the Manika Plateau, almost to Lufira Falls. 

4. Wetlands of the Central Zaire Basin 


Co-ordinates of Region: 3°00'N-4°00'S/16°00'-26°00'E 



General: The central depression of the Zaire Basin is largely covered by 

high tropical rain forest with a canopy often over 45 m high. This is the 

largest expanse of this type of vegetation in Africa, and the numerous 

rivers which drain it are essentially forest rivers; they are all slow 

flowing, the broader ones with lacustrine characteristics. The area is flat 

or very gently undulating, with a general inclination towards the west. 

(a) Riverine Swamps & Forests 


General: The Kasai River (known as the Kwa in its lowest course), 

always over 2 km wide and in one place reaching 8 km in width, skirts the 

southern edge of the depression between Ilebo (= Port Francqui, 

4°20'S/20°35'E) and its confluence with the Zaire River (3°10'S/16°12'E), 

collecting the water of all the streams flowing down from Angola across 

Kasai and southern Bandundu Provinces. It also drains the southern part 

of the central depression, receiving the waters of the Lukenie River, 

together with those collected into Lake Mai Ndombe, through its major 

north bank tributary, the Fimi River. 

Low plateau land, at an elevation of about 500 m, forms the eastern 

boundary of the depression and another block of elevated land between 

the Zaire and Oubangui Rivers forms the northern boundary. The Zaire 

River traverses the northern side of the depression, flowing from east to 

west in an island studded bed. This reaches 17 km in width where Sumba 

Island (90 km long) interrupts its course (1°44'N/19°33'E). Along the 

north of the depression the Zaire River receives, on its north bank, 

numerous tributaries draining the elevated land between it and the

Oubangui, which here flows in parallel farther north. In passing 

downstream from Kisangani the principal tributaries are the Tshopo, 

Lindi, Aruwimi, Itimbiri (which forms a substantial delta in the Zaire 

River, so sluggish is the current) and Mongola Rivers. Large swamp forests 

and raphiales cover the lower valley floors of all these tributaries, e.g. there 

are at least 150 000 ha of swamp in the Itimbiri River system, including a 

solid block of over 54 000 ha which occludes the lower valley floor with 

a mean width of 9 km over a 60 km stretch, immediately above its delta. 

All the streams draining into the Itimbiri carry swamp forest almost to their 

sources, and such is the case for all the other north bank tributaries. 

The entire plateau area between the Zaire and Oubangui Rivers is scored 

by the strip swamps of riverine wetlands, always comprising 5-10% of the 

land surface, but 20-40% to the south of Gemena (3°13'N/19°48'E) in the 

upper reaches of the Mongala and Giri Rivers, and to the west below the 

confluence of the Lua Dekere and Lua Vindu Rivers. In the northeastern 

borderlands all streams in the catchments of the Mbomou and Uele Rivers are 

swampy, and after their confluence, to form the Oubangui at Yacoma 

(4°05'N/22°22'E), both its course and that of its tributaries are swampy. The 

bed of the Oubangui forms the border with the Central African Republic, and 

thereafter, that with Congo, and its most important tributaries enter from those 

countries. 

In the central part of the depression, south of the Zaire River, all the major 

streams, with the exception of the Lomami, flow roughly E-W again parallel to 

the Zaire, and many carry substantial areas of swamp forest in their shallow 

valleys, e.g. swamps occur upstream from the confluence of both the Lulonga 

and Ruki Rivers with the Zaire River. Both rivers bifurcate into lesser tributary 

streams, and on these, swamps are equally well developed. The Ruki, for 

example, divides to form the Momboyo and the Busira. Swamps occur on 

both these rivers above their confluence to form the Ruki. There is a block of 

25 000 ha on the Momboyo, and another of 55 000 ha on the Busira, between 

19°00' and 19°27'E. Farther upstream, near Boende, the Busira River divides 

at the confluence of the Tshuapa and Lomela Rivers. This is in the wet heart 

of the central depression where mean annual rainfall exceeds 2000 mm/yr and 

there is no dry season. Both the Tshuapa and Lomela carry broad swamp belts 

along their banks. There is a block of permanent swamp forest along 165 km of 

the Tschuapa from 20°33' to 22°00'E, covering about 160 000 ha, and another 

of 88 000 ha on the Lomela from 20°35' to 21°30'E, through which the river 

meanders for 110 km, and farther up this river, yet another block of 46 500 

ha between 21°50' and 22°18'E. Land subject to inundation accounts for 20- 

25% of the total land surface throughout parts of the Tshuapa catchment. By 

contrast to the foregoing rivers, the Lomami flows from south to north, parallel 

with the Lualaba section of the Zaire River, and joins it after that river has

swung west. The confluence of the two rivers is 125 km downstream from 

Kisangani. Extensive swamps occur in the lower valley of the Lomami, and 

on the bank of the Zaire River opposite the Lomami mouth. 

At a longitude of 20°E the Zaire River swings SW to Malebo Pool and in this 

section, along its left bank, collects all the tributaries draining the central 

depression, including the Ruki and finally, the Kasai. Throughout their courses 

the Kasai, Oubangui and Zaire Rivers flow over a broad alluvial plain, and 

although by no means continuous, behind their levees are seasonally flooded 

forests which extend away from the rivers on deep alluvium for distances of 

up to 50 km. Seasonally flooded forest also covers or fringes many islands in 

the river, and at the riverside, on low islands in midstream and in 

depressions in the seasonally flooded forests there are patches of permanent 

swamp forest. On the south bank there is a block of swamp forest, 

covering 68 000 ha just west of Kisangani and a major block along 250 

km of river frontage from 18°45' to 21°40'E, covering some 425 000 ha, 

opposite Sumba Island. Here, the land is traversed by anastomosing 

channels, parallel with the main river, in what is effectively an inland delta. 

However, the largest expanse of permanent swamp forest occurs at the 

western side of the depression, where the streams draining the central part 

flow into the Zaire River. Here, a virtually continuous block of permanent and 

seasonally flooded forest extends along the left bank for 250 km below 

the Ruki River mouth near Mbandaka (= Coquilhatville, 0°03'N/18°28'E), 

and inland for 275 km, covering about 5 000 000 ha and encompassing Lakes 

Tumba and Mai Ndombe. Immediately south of this, opposite the mouth of the 

Alima River which enters from Congo, another swampy block 70 km wide and 

up to 30 km deep covers over 190 000 ha along the Sangasi Itoka and other 

small tributary streams. 

Throughout the central depression, away from areas subject to inundation as a 

consequence of rivers overflowing their banks, rain swamps develop in 

depressions in which the water table is close to the surface and which may be 

intermittently flooded by rain. 

On its right bank the Zaire River receives the Oubangui, which has also turned 

sharply south to form the border with Congo for 500 km, and to meet the Zaire 

River at point 0°27'S/17°47'E. An enormous area of permanent swamp exists in 

the triangle of low flat land between them. This measures 375 km along the 

perpendicular from base to apex (at the confluence) and 165 km across the 

base in the north and comprises some 3 000 000 ha of permanently 

waterlogged or flooded forest. The Giri River, rising near Kungu 

(2°50'N/19°19'E) almost bisects this triangle of land, providing a trench 

roughly along the perpendicular, and flowing into the Oubangui just before 

that river enters the Zaire River. Numerous channels, up to 50 km long, connect

the Giri and Zaire Rivers through the swamps, along the eastern side of the 

triangle. At the confluence with the Oubangui, the Zaire River is fully 15 km 

wide. 

Wetland Flora 

The unflooded parts in the west and centre of the great depression are 

covered by evergreen forest, but on the elevated lands bordering it in the far 

northeast and southeast, where rainfall is less, the forest becomes semideciduous 

in nature. In all cases, where the forests are undisturbed, the 

wetlands are dominated by arborescent species, and the swamp forests tend to 

grade into terrestrial forests through extensive transition zones in consequence 

of the flatness of the land. In some places, floating grass swamps occur along 

the rivers in areas of deep semi-permanent inundation, with swamp forests 

farther away from the rivers on less deeply inundated ground. 

Riparian & Floodplain Associations: In the north of the region, between the 

Oubangui and Zaire Rivers, where agriculture is most intense, Thalia 

welwitschii (Marantaceae) swamps become established along rivers where 

the gallery forest has been destroyed. The existence of this vegetation 

depends upon a variable water level and a fairly swift current, at least in the 

wet season. Thalia is an obligate heliophyte, and these swamps, which 

contain few associates, quickly deteriorate if trees reappear. If the water 

levels are lower and less variable, and the water movement is sluggish, 

Cyrtospenna senegalense becomes established and is usually quickly 

succeeded by arborescent species. 

Other secondary associations occur in the higher country between the Zaire and 

Oubangui Rivers, between 500-700 m asl. Here, Loudetia phragmitoides 

swamps occur along the edges of gallery forests on poorly drained soils. 

These swamps include such other species as Cyclosorus striatus, 

Cyperus halpan (= C. halpan), Eulophia caricifolia, Ludwigia 

africana, Lycopodium cernuum, Sauvagesia erecta and Torenia 

parviflora. They occur where the water table is always high and periodic 

flooding occurs, where as on better drained soils, where fires frequently 

occur, Imperata cylindrica becomes dominant. 

Also in this region, where pools and quiet backwaters in the narrow parts of 

rivers are heavily shaded by gallery forest, a Nymphaea lotus-Utriculara 

thoningii community develops. This is floristically impoverished by the 

low light intensities. By contrast, where the canopy is open there is a 

much richer vegetation. Provided that water movement is minimal, water 

levels seem unimportant and here, Nymphaea maculata is dominant, while 

Eleocharis acutangula, Fuirena stricta, Hydrocharis chevalieri and 

Sabicea africana are the most common of a dozen or more associates.

Pioneer Associations: The pioneer species on sandy banks along and in the 

large rivers of the central depression is Panicum repens, which is soon 

joined by Acroceras zizanoides, Cyperus erectus, C. nzaculatus and 

Hemarthria natans, leading finally to a sward of Cynodon dactylon where 

inundation is infrequent. By contrast on mudbanks, the pioneers are 

Basilicum polystachyon, Commelina diffusa, Eclipta prostrata, Ipomoea 

reptans and Ludwigia repens. Meadows of aquatic grasses develop in deep 

water along the banks of backwaters, and here Echinochloa pyramidalis, 

E. stagnina and Vossia cuspidata are the most frequently encountered 

species, but in shallower places Phragmites mauritianus or Cyperus 

papyrus may cover extensive areas in monospecific stands. Little 

depressions on islands in the river are colonised by Cyperus 

longibracteatus and Rhynchospora corymbosa when they fill up, usually 

with some persistent Echinochloa pyramidalis. Open surfaces in quiet 

backwaters tend to be covered by Lemna paucicostata, Nymphaea 

caerulea, N. lotus, Pistia stratiotes and Utricularia spp., but 

comparatively recently Eichhornia crassipes has been introduced and tends 

to dominate this habitat, and also to invade the areas normally supporting 

floating grasses. It has become a serious threat to navigation in certain 

localities. Steep sandy river banks and cliffs are covered at water level by 

plaques of Marchantia chevalieri, and above the water by a tracery of ferns 

dominated by Dicranopteris linearis. On any slips or shelves however, 

and on the tops of the cliffs, the forest vegetation quickly takes root, in 

particular Anthocleista nobilis, Barteria nigritiana, Caloncoba 

welwitschii, Vernonia conferta and occasionally, Alchornea cordifolia. 

As they become more elevated, islands are colonised by woody species, first 

by single trees, or little clumps of Alchornea cordifolia with Bridelia 

micrantha, Ficus mucuso and Spondianthus preussii, often with abundant 

Mimosa pigra. This pioneering woody vegetation is quickly entangled by 

creepers, and Alchornea is usually dominant in the early stages of the 

succession. However, in the east of the region at least, a tall forest of Lannea 

welwitschii, with Ceiba thonningii, Ficus mucuso, Oxystigma buchholzii, 

Pseudospondias microcarpa and Spondianthus preussii quickly replaces 

the Alchornea association. Occasionally Elaeis guineensis may be 

encountered in this vegetation, and the understorey becomes moderately thin 

with Leptonychia batangensis the most characteristic species. At the 

upstream ends of islands, erosion during high floods may cause trees to be 

uprooted, and when the waters subside the gaps so formed tend to be filled by 

stands of the coarse herb Costus lucanusianus. Swampy depressions on the 

islands and along the river banks are covered by a forest containing Albizia 

laurentii, Chrysobalanus atocorensis, Coffea congensis, Irvingia smithii, 

Uapaca heudelotii and Trichelia retusa, and there may be extensive

monospecific stands of Uapaca guineensis, both on the islands and along 

the mainland riverbanks. The strong currents which arise during the periods of 

high flood in the main river channels seem to inhibit the development of other 

seral stages. 

In the north of the region, between the Zaire and Oubangui Rivers, the 

banks of tributaries subject to regular inundation are colonised by 

Alchornea cordifolia, Macaranga saccifera and Raphia laurentii, all 

heliophilic species. This tends to be succeeded by Mitragyna stipulosa 

forest described below, but the floodplain forests on the valley floors of 

these rivers usually become separated from the water in the river channel 

proper, by a narrow strip of riparian fringe forest. This fringe forest grows 

where inundation is semi-permanent, and it contains characteristically, an 

abundance of Uapaca heudelotii with Antidesma leptobryum, Embellia 

retusa, Flacourtia sp., Hymenocardia heudelotii, Parinari congensis, 

Trichelia retusa and Uvaria laurentii as common associates. 

Floodplain Forests: Behind the riparian strips periodically inundated 

forests occur. Several types of riverine swamp forest are encountered along 

tributary rivers, differing quite markedly in their physiognomy and depending 

for their existence upon different soil types. Floristically these forests are quite 

diverse, varying in composition from place to place across the vast central 

depression and often they are mosaics of different associations. However, 

to generalise, on muddy soils along watercourses, where inundation is 

periodic, but deep and frequent, and where the water flows only very slowly, 

the forest is usually dominated by Mitragyna stipulosa. 

Mitragyna is found everywhere, but its associates vary. Among the most 

widespread are Alstonia congensis, Anthocleista liebrechtsiana, 

Anthonotha pynaertii, Baikiaea insignis, Berlinia bruneelii, Brazzeia 

congoensis, Crotonogyne giorgii, C. poggei, Dialium pachyphyllum, 

Dichostemma glaucescens, Eriocoelum microspermum, Macaranga sp., 

Nauclea diderrichii, N. pobeguinii, Ouratea arnoldiana, Parinari 

glabra, Syzygium gilletii, S. guineense ssp. huillense, Uapaca heudelotii, 

Voacanga thouarsii, Xylopia aethiopica and X. rubescens. 

Ancistrophyllum secundiflorum, Calanzus deeratus, Eremospatha spp. 

and Popowia lucidula are scandent species. Cyrtosperma senegalense 

and Marantochloa congensis are common in the understorey. The canopy 

of this type of forest reaches 30-40 m. 

In places where the water moves quite swiftly, and where inundation is less 

prolonged and the soils are sandy, the forests are dominated by Guibourtia 

deineusei. The forest is dense and the canopy reaches or exceeds 30 m, but the 

under-storey is sparse. Common associates in this forest type are Brazzeia

eetveldeana, Casearia congensis, Cleistanthus libericus, Coffea congensis, 

Cremaspora triflora, Dialium reygaertii, Drypetes angustifolia, Garcinia 

pynaertii, Hymenocardia heudelotii, Memycylon sp . , Mimusops 

warneckei, Mapania bieleri (Cyperaceae), Morelia senegalensis, 

Popowia lucidula, Salacia pallescens, Scytopetalum pierreanum and 

Xylopia katangensis. 

Along the lower courses of tributaries to the Zaire River, in the east of the 

depression, the lowest parts of the valley floors, which are almost 

permanently flooded but constantly flushed by moving water, tend to be 

covered by a forest distinguished by an abundance of Lasiodiscus mannii, 

Raphia spp. and Uapaca guineensis. On either side, in the wider valleys, 

strips of Mitragyna stipulosa forest grade into broad belts of pure 

Gilbertiodendron dewevrei forest, at higher and less frequently inundated 

levels. Gilbertiodendron forest occurs on hydromorophic soils, but is 

transitional to terrestrial forest, and in the north often contains a 

substantial proportion of Anopyxis klaineana. 

Patches of alluvium build up away from the current on the quiet sides of 

meander bends in all the larger rivers, and deltas have developed where 

tributary streams enter quiet stretches of the Zaire River. These muddy 

sites are first colonised by Alchornea cordifolia, but this is quickly 

succeeded by mixed forest, leading to a stage dominated by Alstonia 

congensis, and this in turn eventually gives way to an Entandrophragma 

palustre forest. This latter species may be found in association with 

Anubias affinis, Dichostemma glaucescens, Elaeis guineensis, 

Mitragyna stipulosa, Myrianthus scandens, Pycnanthus marchalianus, 

Raphia spp., Ricinodendron palustre, Sersalia palustre and Symphonia 

globulifera, but it sometimes occurs in almost monospecific belts more than 

5 km wide. This association constitutes one of the last stages of the 

hydrosere, preceding Gilbertiodendron dewevrei forest, which usually 

provides a transition to terrestrial rain forest. 

Permanent Swamp Forests: In some shallow basins, away from the 

rivers, where inundation is more or less permanent and the surface water is 

semi-stagnant, the forest is characterised by an abundance of Sterculia 

ambacensis. In these sites the soil surface is always muddy, and most 

arborescent species have either tall flanged buttresses or stilt roots. The 

buttresses of Sterculia anzbacensis are narrow and plank-like, several metres 

tall at the base of the trunk, but often wind tortuously over the forest floor with 

heights of 50-100 cm for distances of up to 15 m. In this type of forest the 

most common associates are Coelocaryon botryoides, Lasiodiscus 

mannii, Miinusops warneckei, Pseudagrostistachys ugandensis, 

Pseudospondias microcarpa, Symphonia globulifera and Treculia

africana. 

Wetland Fauna 

There is a rich fish fauna. Within the central depression, the three major rivers 

provide 3150 km of continuous river surface, 2-15 km wide, providing well 

over 2 000 000 ha of water, open to the sun and wind. On either side of the 

rivers there are strips of swamp forest providing, probably, a further 8 500 

000 ha of seasonally aquatic habit, but throughout this area, there are 

permanent swamps which never drain. The myriad tributaries of these three 

principal rivers have a different character. They are mostly quicker flowing, 

and those under 50 m wide are generally shaded by the forest, with lower 

water temperatures. They also have narrower floodplains. The fish fauna 

changes across the central depression, but in any one place it is possible to 

distinguish different faunas in different habitats; in the open waters of the main 

rivers, along the banks, in the creeks, coves and meadows of aquatic 

vegetation, in the permanent swamps, and on the floodplains. Rapids or 

waterfalls isolate this giant system, situated 300-425 m asl, from the estuarine 

section of the river and the streams of the highland parts of the Zaire Basin. 

Having said this, the fish fauna of the river is not known in any detail. Studies 

have been made at Malebo Pool (Poll, 1959) at the lower end of the 

depression, at Yangambi (0°47'N/24°24'E) far up the Zaire River (Gosse, 

1963), and at Ikela (1°06'S/23°06'E) way upstream on the Tshuapa River 

(Matthes, 1964). Many fish leave the rivers to spawn in the forest at high 

water, moving back to the channels when the floods recede, but the juveniles 

of some species remain in the permanent swamps. The number of species found 

in the forests and swamps is far lower than that found in the river, and in the 

river the number of both individuals and species is greater along the banks than 

in the open waters. At Yangambi, of 43 Mormyridae identified, 38 species are 

found in the river, 14 in the tributaries and 6 in the swamps. Of 14 cichlids, 7 

are found in the river, 6 in the tributaries and 1 in the swamps, and of 10 

anabantids, 5 occur in the river, 8 in the tributaries and 3 in the swamps. 

The permanent swamp dwelling fishes have accessory breathing organs since the 

swamp water is semi-stagnant, and the bottom layers are completely 

anoxic. Those so far identified are Clarias spp., Clariallabes melas, 

Chanallabes apus, Ctenopoma fasciolaturn, Ctenopoma sp., 

Hemichronzis bimaculatus, Pantodon buchholzii, Papyocranus sp., 

Paraophiocephalus obscurus, Pekatochromis ocellifer, Phractolaemus 

sp., Polypterus palmus, Protopterus aethiopicus, P. dolloi and 

Xenomystus nigri, 17 species in all. The numerous high water visitors 

include Hepsetus odoe. These swamps never dry out, so that the protopterans 

do not aestivate as they do elsewhere in Africa.

Huge shoals of plankton feeding Microthrissa are pelagic in the rivers, 

migrating up and downstream seasonally. Small species of Barbus and 

Clupeopetersius, and their predators such as Hydrocynus vittatus, also 

occur in pelagic situations. Among benthic fish there are many insect or 

detritus feeders in the rivers, e.g. species of Barbus, Chrysichthys, 

Synodontis and Tylochronzis, also Citharinus, a mudsucker, and 

piscivores, including other species of Chrysichthys, Mormyrops and 

Polypterus, and species of Labeo and Tetraodon where the bottom is sandy 

and the current swift. Large species of Clarias, weighing as much as 150 

kg, have been taken from deep holes on the downstream sides of islands, 

and here also live very large specimens of Heterobranchus and Lates 

niloticus, the latter attaining weights of 50 kg. Malapterus electricus is 

common throughout the system. 

Two crocodiles, Crocodylus cataphractus and C. niloticus, occur in the 

rivers, also Varanus exanthematicus, Pelomedusa sp., Pelusios sp., and 

aquatic or semi-aquatic snakes including Boulengerina annulata, 

Dromophis lineatus, Philothamnus irregularis, Natriciteres olivacea, 

and Python sebae. In the trees there are other snakes, including 

Dendroaspis sp., Dispholidus typus, Philothamnus sp. and Thelotornis 

kirtlandii. The spectrum of birds is very similar to that described in section 

1, Bas-Zaire. 

Mammals in the system include the usual aquatic types, Aonyx congica, 

Atilax paludinosus, Dasymys sp., Hippopotamus amphibius and Lutra 

maculicollis, with Osbornictis piscivora confined to the north. Species of 

the swamp forests include Cephalophus monticola, C. sylvicultor, 

Genetta tigrina, Hyenzoschus aquaticus, Kobus ellipsiprynznus, 

Loxodonta africana cyclotis, Loxodonta pumilio (sometimes said to be 

another form of L. africana cyclotis), Manis gigantea (N only), M. 

tetradactyla, Neotragus batesi (NE only), Syncerus caffer nanus, 

Tragelaphus scriptus and T. spekei. The pygmy chimpanzee, Pan 

paniscus, is widespread though uncommon in the central depression 

between the Zaire, Lualaba and Kasai Rivers. It visits seasonally flooded 

forests during dry periods. Potamochoerus porcus is locally abundant, 

while Phacochoerus aethiopicus occurs in the eastern parts, but is most 

common east of the Lualaba and west of the Oubangui in Congo. Felis 

aurata and Panthera pardus are also known from the region. Many 

monkeys live in riverside forests, e.g. Allenopithecus nigroviridis (N 

only), Cercocebus aterrinzus, C. albigena, C. galeritus chrysogaster 

(south of the Zaire River to the Lukenie and east to the Lomami), 

Cercopithecus aethiops cynosurus (S only), C. ascanius, C. l'hoesti (E 

only) C. nzitis maesi, C. stuhlmanni (NE only), C. mona wolfs (W only), 

C. mona elegans (E only), C. mona denti (NE only), C. neglectus, C.

nictitans (NW only), C. pogonias grayi (N only), Colobus badius, C. 

guereza (N only), C. poly-komos and Miopithecus talapoin (W only). 

Other arboreal species include Anomalurus beecroftii (NE only), A. 

derbianus, A. pusillus (N only), Dendrohyrax arboreus, Funisciurus 

congicus (WC depression), F. pyrrhopus (N only), Galago 

demidovii, Heliosciurus rufobrachium, Idiurus macrotis (N only), I. 

zenkeri (N only) and Zenkerella insignis (W only). 

Human Impact & Utilisation: Throughout the central depression, land 

which is subject to regular inundation is generally still in pristine 

condition, since, traditionally, it has been regarded as having no 

agricultural potential. However, in a number of sites adjacent to the banks 

of the larger rivers, where inundation is distinctly seasonal, there have been 

extensive local clearances for rice production. Almost all the rivers are 

fished, and the major streams provide the principal communication 

routes to the interior, linking the railheads at Kinshasa, Ilebo, Bumba and 

Kisangani, and providing the only viable route for cargo from Kinshasa to 

many major centres. The Zaire and Oubangui Rivers are also used by 

traffic to ports in Congo and the Central African Republic. 

Conservation Status: A large area, c. 3 600 000 ha, of the southern 

central depression is protected in the Salonga National Park. This is in 

two sections, separated by a broad corridor of land. The southern section 

includes the watershed separating the Luilaka River in the north from the 

basins of the Lukenie River in the south and the Lokoro River in the west. 

Part of the Lomela River system is protected in the northern section. The 

park is very poorly explored, from the biological point of view. Access is 

by river and there are neither tourist facilities nor management plans. 

The area has been left as wilderness. 

Along the northern border, the Bomu Nature Reserve lies along the south 

bank of the Bomu River, extending from a point about 40 km above the 

confluence with the Oubangui River for about 500 km to the border with 

Sudan. Within this reserve, in addition to the south bank of the Bomu 

River, which forms the border with the Central African Republic, there are 

the valleys of several tributary rivers including the Asa and Gwane. The 

far eastern section of the park is much drier than other parts of Zaire with 

a long dry season, during which temperatures may rise above 35°C and 

desiccating NE winds blow from Sudan. There are nevertheless extensive 

wetland areas in the reserve, including Loudetia and papyrus swamps and 

flooded gallery forests. 

(b) Lake Tumba


Coordinates: 0°37 '-1°00 'S/17°49' -18°09'E 

Area: 76 500 ha (open water) 


Nearest Towns: Mbandaka (80 km NNE); Kinshasa (480 km SE) 

General: The lake is shallow, increasing in depth from 3 m in the south 

to 8 m in the north, at the entrance to the Irebie Canal, through which it 

drains to the Zaire River. The banks are steep with the maximum water 

depths being found close to the banks. The periphery is cloaked by 

forest, some of which is unflooded, but much of which is seasonally or 

permanently inundated. In sites of deepest inundation the forest gives way 

to herbaceous swamp. There are several small islands in the lake, and 

affluent streams have formed small deltas. 

Climate: The lake enjoys about 2000 hours of sunshine a year, with little 

variation from month to month. Total incident radiation amounts to 133 

Kcal/cm 2 /yr. Wind speeds tend to rise from 4 km/hr in the early morning 

to about 8 km/hr at midday and then die back to 3 km/hr by the evening. 

Winds are predominantly from the south during low water periods but 

swing to the west during the high water periods. Occasionally there are 

violent storms. Mean annual rainfall is 1800 mm, with maximum 

intensity in October and November (200-220 mm/month) and February- 

April (170-200 mm/month), and a minimum in July when only 70 mm 

may fall. Relative humidity is 80-90% throughout the year, and 

evaporation from the lake is estimated as 1300 mm/yr. Mean annual 

temperature is 25.5°C. The mean monthly figure for March-April is also 

25.5°C, with mean daily maxima and minima of 31.5 and 21.5°C. The 

corresponding figures for July are 24.5, 29.5 and 21°C. 

Hydrology & Water Quality: The lake was formed in recent times by 

the obstruction of a tributary river close to the point where it discharged 

into the Zaire River, leading to the inundation of part of its shallow lower 

basin. It has several affluents draining a region of permanently and 

seasonally inundated forests. However, water may enter it from the Zaire 

River at times of high flood. Water level fluctuates by about 4 m a year, 

but there are also important fluctuations of the mean lake level from year 

to year. 

The lake is unstratified and the water temperature varies between 26- 

33°C over the course of a year, with Secchi depths of 90-100 cm in midlake 

and c. 75 cm near the banks. The waters are humic, stained brown 

and acidic, with a pH range of 4.5-4.9. Salinity is low with a total mineral 

content of 30-35 mg/I. By contrast suspended organic matter is high, also 

accounting for 30-35 mg/l. Dissolved oxygen is however, relatively

abundant throughout the water column and throughout the year, there 

generally being 4-6 mg 0/1, representing 50-70% saturation. 

Wetland Flora: In calm coves the lake water is covered by floating mats 

of Echinochloa pyramidalis and Panicum parviflorum, which towards the 

banks merges into a bed of Jardinea congoensis and J. gabonensis, with 

thickets of Cyrtosperma senegalense and Rhynchospora corymbosa. This 

peripheral vegetation may extend out into the lake for 100 m or more, 

where the edges may be broken up by wave action to create free drifting 

masses. These, if they come to shore, start fresh colonies. Pools of open 

water are quite common within the meadows of floating grasses, and are 

sometimes partly occupied by an association of Nymphaea lotus and 

Utricularia benjaminiana. Eichhornia crassipes is sometimes dragged 

into the lake by boats, or enters at times of very high floods from the Zaire 

River, but does not become established, possibly because of the acidity of 

the water. 

The junction of the herb zone with swamp forest on the banks is marked 

by the development of a shrubbery, dominated by Dissotis segregata. 

Where the bank is steep, swamp forest develops on the lakeward side of 

the bank, in sites only exposed at the periods of lowest water, and thus 

submerged up to 4 m deep at high water. The dominant tree is Irvingia 

smithii, with Alchornea cordifolia and Cynometra schlechteri as the most 

abundant associates. A little higher, in the zone of periodic inundation, 

the forest is dominated by Guibourtia demeusei and Uapaca heudelotii. 

Swampy banks of gentle slope are colonised by a forest of Oubanguia 

laurentii, with an abundance of climbing palms, particularly 

Eremospatha macrocarpa. This forest merges with the Guibourtia- 

Uapaca forest, since on rising land the forest floor is periodically exposed. 

At the edge of the inundation zone, still on ground with a water table close to 

the surface, Guibourtia forest merges with evergreen rain forest. 

Wetland Fauna: Some vagrant species of fish enter the lake from the Zaire 

River during high floods but do not develop populations in the lake. 

Altogether 111 resident species have been identified in the lake, together 

with about a dozen vagrants. Open waters support populations of small, 

plankton feeding, shoaling fish, belonging to the genera Barbus, 

Clupeopetersius and Microthrissa, together with their predators, such as 

Hydrocynus vittatus, Mormyrops deliciosus and Odaxothrissa losera. 

There are numerous mudsucking, detrivores or insectivores, which fall prey 

to other carnivorous species of Chrysichthys, Malapterus, Monnyrops and 

Polypterus. The plant communities of the quiet coves, with their abundant 

invertebrate faunas, attract many species feeding on vegetation, insects, 

freshwater crabs and detritus. Another spectrum of predatory fish occurs

here. An unusual group of predators, well represented in the lake, are those 

feeding almost exclusively on fins torn off other fish. These include species 

of Belonophago, Eugnathichthys and Phago. Endemism is low, and only 

Clarias congicus, Clupeopetersius schoutedeni, Congolensis tumbanus, 

Eutropius tumbanus, Lamprolagus congolensis and Tylochromis 

lateralis microdon have distributions restricted to the lake and its 

immediate environs. 

Amphibians and their tadpole stages are abundant in the aquatic prairies near the 

banks. Crocodylus cataphractus is common, and C. niloticus is present 

though far less common. A tortoise, Amyda sp., varanid lizards, and some 

terrapins also occur here, together with numerous snakes, including 

Boulengerina annulata, Python sebae and various tree snakes. Most 

snakes associated with the lake are piscivorous. The birds and mammals are 

similar to those described in the previous section, 4a. 

Human Impact & Utilisation: The human population is comparatively 

high on the eastern side of the lake, above average for the Zaire 

Depression, and reaches a density of 15 persons/km 2 . Here the principal 

town, Bikoro, has over 1000 inhabitants. By contrast the west bank is very 

sparsely populated, with a density of less than 3 persons/km 2 . The lake is 

fished commercially and the annual catch varied between 2000-3500 

tonnes between 1964-1983 and most of the local people are engaged in, or 

associated with, the fishing industry, but there is some local agriculture. 

The principal species fished belong to the genera Chrysichthys, 

Citharinus, Clarias, Eutropius, Mormyrops and Xenomystus. There is a 

cargo and passenger boat service between Bikoro and Mbandaka which 

takes 21 days for the return trip, and carries on average 400 - 1200 tonnes of 

cargo upstream, returning with 1300-1800 tonnes. 

Conservation Status: No part of the lake is protected, but it is proposed that 

the bays and channels of Bituka, Lobambo and Nganga on the sparsely 

populated southern and western shores should become an integral nature 

reserve. It is thought that the creation of such a reserve would not interfere 

with profitable fishing on the lake. 

(c) Lake Mai Ndombe 



Area: c. 230 000 ha (open water area) 

Altitude: c. 310 m as1 

Nearest Towns: Bolobo (225 km W); Kinshasa (375 km SE) 

General: The lake is entirely surrounded by equatorial forest and measures

135 km in length, with a mean width of 17 km. It is oriented N-S and reaches a 

maximum width of 55 km in the north, but tapers to a point where it 

discharges into the Fimi River in the south. The lake occupies an alluvial 

depression. It forms the lowest point of a shallow swampy basin and around 

most of its perimeter its banks shelve gently into the water and are densely 

forested. The water is shallow with a mean depth of perhaps 3 m. On the east 

and southwest the beds are of Pleistocene, or even Pliocene age, dating from 

the time when the entire depression was flooded, but in the northwest the 

beds are very recent. 

Climate: The lake enjoys about 2100 hours of sunshine a year, with monthly 

receipts ranging from 140-185 hours, with maxima in May-June and a 

minimum in November. The mean annual incident radiation receipt is 127 

Kcal/cm 2 and evaporation from the lake has been estimated as 1356 mm/yr. 

Relative humidity varies between 80-90% throughout the year, but with the 

lowest values, c. 80% being recorded at the southern extremity in August. The 

mean annual temperatures are close to 25.3°C all over the lake, with a mean 

figure of 25.9°C in March, and mean monthly maxima and minima of 30.9 and 

22.4°C respectively, while the corresponding figures for November are 24.7, 

29.4 and 21.1°C. Wind speeds are similar to those reported for Lake Tumba, but 

violent gusts are uncommon. Mean annual rainfall increases from 1700 mm in 

the south to 1900 mm in the north. Maximum falls of up to 225 mm occur in 

October, and minimum falls in July range from 10-50 mm. There is a short 

but distinct dry season, lasting 50 days in the north but nearly 80 days in the 

south over the June-August period. 

Hydrology & Water Quality: Lake Mai Ndombe has 14 major affluents 

draining some 6 768 000 ha of very wet swampy land, the most important of 

which are the Lokoro and Lotoi which enter the northeastern arm of the lake 

and the Olongo Lule which enters the northwestern arm. The lake spills over 

into the Lukenie River, draining another huge area to the east, which is 

thereafter known as the Fimi River. This eventually discharges into the Kasai 

River. The black humic waters of Lake Mai Ndombe do not immediately mix 

with the clear waters of the Lukenie, so that after the confluence, the Fimi River 

has a ribbon of black water along the north bank and a ribbon of clear water 

along the south bank. Following the confluence with the Kasai, the brown 

Fimi waters also remain separate from the reddish Kasai waters for a long 

distance. Low water in the lake is reached in September and high water is 

from January-April, and there is an annual fluctuation of about 2 m in water 

level. The variation of mean water level also fluctuates by about 2 m from 

year to year. The rise of water levels during October-November is due in 

part to water entering from the Lukenie, with water flooding across country 

from this river 50 km upstream of the point where it picks up the effluent 

from Lake Mai Ndombe. It has been estimated that the water content of

the lake varies from 4-10 billion m 3 over the course of a year. 

The temperature is quite high, but there are no reliable figures. However, 

judging from the incident radiation regime and its shallowness, and drawing 

parallels with Lake Tumba, it is probably in the range of 28-30°C. The waters 

are dark and transparency is low, c. 80 cm. The pH range is 4.0-4.5. The water 

column is oxygenated throughout, but never saturated, and the level of 

mineralisation is very low. 

Wetland Flora: Most of the lake is still completely enclosed by virgin 

equatorial forest, except in the immediate vicinity of a few small villages 

and in the far south where, between the banks of the Lukenie and Fimi Rivers 

and the southern tip of the lake, much seasonal swamp forest has been cleared 

for agriculture. Virtually all the surrounding forest is subject to periodic 

inundation, but permanent swamp forest is concentrated in the north, along the 

courses of the rivers entering there. The most extensive area is from the NE 

arm of the lake southeastwards along the Lokoro River, where the main block 

extends for 153 km upstream and in places spreads for over 40 km on either 

side of the river. Patches of permanent swamp forest also occur farther upstream 

on the Lokoro and its tributaries, the Lole and Lula Rivers, and this is the case 

on all the affluent streams. Raphia swamps occur around the shores in the 

wettest sites, made impenetrable by the presence of spiny climbing palms, 

principally Eremospatha spp. These grade into Oubanguia africana and 

Guibourtia denteusei forests in less permanently inundated places, and 

these in turn to terrestrial evergreen rain forest on unflooded land. There have 

been no proper botanical surveys of Lake Mai Ndombe. 

Wetland Fauna: There have been no zoological surveys of Lake Mai 

Ndombe, and what is known stems from travellers reports. Among 

invertebrates, the medusa of Limnocnida congoensis has been found there, and 

freshwater crabs, Potamonautes spp., are plentiful. As far as the fish fauna is 

concerned, some inventories were made at the beginning of this century. By 

1918 some 40 species were known from the lake including Alestes 

binzaculatus, Gnathonenzus leopoldianus, Marcusenius nigropinnis and 

Notopterus afer. Alestopetersius leopoldianus, A. nigropterus and 

Nannothrissa stewartii are endemic. The lake contains terrapins, 

Pelosios spp., and three crocodiles, Crocodylus cataphractus, C. niloticus 

and Osteolaemus tetraspis (de Bondt, 1969); also Boulengerina annulata 

together with several semi-aquatic snakes. 

The avifauna appears to be rich, and most of the Central African aquatic 

birds are found there, although there are no official lists. A comparatively 

rare species is the small kingfisher, Corythornis leucogaster leopoldi. 

Mammals associated with the lake are similar to those found along rivers in

the central depression dealt with earlier in section 4a. 

Human Impact & Utilisation: Population density around the lake is 

low, about 4 persons/km 2 , but falling to 2 persons/km 2 in the south. The 

two centres of population are Kutu at the confluence with the Lukenie 

River in the extreme south and Inongo on the east bank. There is some 

small scale agriculture and oil palm, Elaeis guineensis, is grown locally 

around the lake, also on a small scale. In the SW, between the lake and the 

banks of the Lukenie and Fimi Rivers, rice is cultivated, and there have 

been extensive clearances for this, the rice being grown in what were 

formerly seasonal swamp forest areas. Some millions of hectares of forest 

have succumbed in an area extending 15-20 km from the lake and river 

banks. Fishing on the lake produces an annual catch of about 1000 tonnes, but 

the maximum sustainable yield has been estimated as 10 000 tonnes in 

1983. There are boat services between the lake and Kinshasa, carrying up 

to 5000 tonnes of merchandise/yr in both directions. 


5. Wetlands of the Eastern Highlands 

Co-ordinates of Region: 4°41'N-8°27'S/28°00'-30°32'E 



General: The region under consideration lies between longitude 28°E 

and the mountainous watershed along the eastern border which separates 

the Central Zaire Basin from the basins of the Rift Valley Lakes. In altitude 

it rises from about 650 m asl in the west to over 3000 m asl at several 

points in the Mitumba Mountains. Along the eastern border there are 6 

principal massifs, all with great plateau-like tops 1500-2000 m asl, all also 

surmounted by higher peaks. It is the elevated plateaux at the feet of the 

mountains that are important for their wetlands. These plateaux, from 

north to south, cover more than 937 500 ha above the western shore of 

Lake Albert, more than 900 000 ha above the western shore of Lake 

Edward, more than 600 000 ha above Lake Kivu, and in three blocks, 

more than 2 750 000 ha along the western shores of Lake Tanganyika. 

Streams from the summits meander over the plateau, with innumerable 

swamps along their courses, in valleys which are little incised, but then 

plunge down the steep and deeply dissected western slopes, with waterfalls 

and rapids, before their beds again flatten below the 1000 m contour, en 

route to the Zaire River. Drainage to the east is by short torrential streams, 

descending by serried steps to the floor of the Western Rift Valley. 

Climate: Climate throughout the region varies greatly with altitude. In

general there is a tight correlation between altitude and the temperature of 

the coldest month. Below 1000 m this is in the vicinity of 23°C, but 19°C at 

1500 m, and below 15°C at 2000 m asl. There is little seasonal variation in 

mean monthly temperature near the equator, but it becomes apparent over 

the Marunga Massif at the southern end of Lake Tanganyika. The 

permanent snow line is close to 4500 m asl, and although this height is 

attained at Mt. Karisimbi (4507 m) and Mt. Stanley (5110 m), a snowfield 

exists only around the latter. Mean annual rainfall exceeds 2200 mm 

between 1000 -1300 m on the western slopes of the plateaux in the 

equatorial zone, and exceeds 2800 mm on some of the higher slopes. 

However, it appears to be less great in an intermediate zone between 

1500 -1800 m asl. Here it seldom exceeds 2000 mm/yr. Precipitation 

decreases progressively in moving north or south away from the equator, 

reaching maxima close to 1500 mm/yr on the Marunga Massif in the far 

south. 

Wetland Flora: There are two principal phytogeographic regions, one 

SoudanoZambezian, and the other Guinean. The former occurs above 

1300 m on the plateaux, on the eastern slopes, and on parts of the western 

slopes. The lower western slopes are the province of dense wet rainforest 

or semi-deciduous forest of Guinean affinity. 

Vast swamps occur on the summit plateaux in the headwater regions of 

the myriad streams, and there are wet formations of lesser extent on some 

of the eastern and western slopes. On the plateaux human activities have 

influenced the marshy vegetation, locally ending to make it very uniform, 

as discussed in the appropriate subsection. For this reason a small number 

of discrete associations can be recognised. Cyperus papyrus dominates large 

deeply inundated areas around lakes and ponds, e.g. around the 4 

Mokoto Lakes NW of Lake Kivu, and in the Kabare (2°28'S/28°47'E) 

district. Small deeply inundated permanent swamps along streams are 

generally covered by Typha domingensis, or by this species together with 

Cyperus latifolius. Miscanthidium violaceurn dominates huge areas of 

swamp on flat wet surfaces away from the main watercourses, though 

small streams may traverse them, when they are generally fringed by 

Typha. Miscanthidium forms tall coarse tufts, 4-5 m high, with a lower 

storey of Scleria spp., and with Nymphaea ntildbraedii on water or mud 

between tufts. Phragmites mauritianus seems to be almost completely 

confined to the eastern slopes where it fringes deeply furrowed 

watercourses on the steep slopes, and spreads out into the small deltas 

which streams build into the lakes. However, Cyperus latifolius is the 

most widespread plateau species. It covers great areas, in almost pure 

stands, reaching 1.5 m in height, but around the edges other heliophilic 

species become abundant and chief among these are Alchemilla

mildbraedii, Polygonum strigosum and Thelypteris squalnigera. This 

association tends to be colonised by woody species, producing a canopy 

around 3 m high, and the most common species involved are Hypericum 

lanceolatunz, Maytenus acuntinatus and Myrica kandtiana. 

At lower altitudes periodically flooded forests along rivers are similar to 

those of the central depression. Uapaca guineensis often forms pure 

stands, but possibly these are secondary in nature. Nevertheless, this 

species is dominant in much of the higher riverside forest, especially 

away from the equator. In the far north and south it is joined by Ficus 

mucuso, Irvingia smithii, Klainedoxa sp., Mitragyna stipulosa and 

Syzygium cf. cordatum in gallery forest, sometimes also by Chlorophora 

excelsa and, in the north, by Khaya senegalensis. Below 1000 m, 

galleries of Gilbertiodendron dewevrei and Staudtia stipitata occur 

along watercourses, but with Mitragyna stipulosa forest in any semipermanently 

swampy areas. Gilbertiodendron forest interdigitates with 

another type of ombrophilous evergreen forest, comprising almost 

monospecific stands of Michelsonia microphylla in the equatorial region. 

This forest occurs under the very wet climate along the lower western 

slopes of the massifs between altitudes of 650-1200 m, on soils that are 

always wet, if not swampy. 

In some of the savanna regions, in places of great seasonal pluviosity, 

where the soil is poorly drained, Kotschya africana and Setaria 

sphacelata often form a mosaic vegetation. 

Wetland Fauna: At the lower elevations the gallery forest, swamp forest 

and riverine forest faunas include Cephalophus nigrifrons, C. 

sylvicultor, Cercocebus albigena (N only), Cercopithecus aethiops, 

C. albogularis (N only), C. ascanius, C. mills stuhlmanni (N only), C. 

mills kandti (Kivu region), Colobus badius, C. guereza (N only), Felis 

aurata, Genetta tigrina, Herpestes ichneumon, H. sanguineus, Kobus 

ellipsiprymnus, K. kob, Leptailurus serval, Neotragus betesi (NE 

only), Osbornictis piscivora, Panthera pardus, Phacochoerus 

aethiopicus, Potamochoerus porcus, and Syncerus caffer. Hylchoerus 

meinertzhageni occurs in montane forests, and Phacochoerus is more 

common towards the east. A cline is evident from west to east, along 

which elephant populations increase in size from the small forest elephant, 

Loxodonta africana cyclotis, to the bush elephant, Loxodonta africana 

africana. The usual small semi-aquatic mammals, Aonyx capensis, 

Atilax paludinosus, Dasymys sp., Lutra nzaculicollis, Pellomys sp. and 

Potamogale velox extend upward into the higher forests, and most occur 

in the plateau herb swamps. Here, at least in the south, Thryonomys 

swinderianus is also present. Aonyx capensis has been recorded above

3000 m, while Atilax and Lutra have been observed 2000 m asl. Aonyx 

congica is uncommon above 650 m. 

Human Impact & Utilisation: Large areas of this region are very 

sparsely populated, but close to small centres of population the 

herbaceous wetland vegetation is heavily exploited for thatch and fibre for 

basketry and fish traps, and it is cut regularly over large areas, limiting the 

dominant vegetation to those species which survive this treatment. The 

rivers are fished throughout the region, illegally in the national parks, 

where there is also some poaching of elephant and antelope. 

Conservation Status: There are 3 national parks in this region. The 

Garamba National Park is situated on the border with Sudan in the far 

north, and here poaching has been intense in recent years. For example, 

elephant numbers in the park fell from 22 000 in 1976 to 8000 in 1983, 

and recurrent civil unrest in neighbouring countries does not improve the 

situation. In this park, in a predominantly savanna area, gallery forest and 

papyrus swamps are protected. To the south, in the Maiko National Park, 

strips of swampy riverine forest are protected, and in the Kahuzi-Biega 

National Park all the wetland types of the plateaux and mountainsides are 

protected. 

6. Lake Tanganyika & the Ruzizi Plain 

(a) Lake Tanganyika 


Coordinates: 3°21'-8°51 'S/29°04 '-31°12 'E 

Area: 3 290 000 ha (c. 1 502 200 ha in Zaire) 


Nearest Towns: Kabalo (255 km W); Lubumbashi (500 km SW) 

General: Lake Tanganyika is 659 km long with a maximum width of 85 

km at the parallel 5°55'S. It is slightly brackish and the second deepest lake 

in the world (1470 m). It lies in the western arm of the Great Rift Valley 

and down most of its western side the escarpment plunges straight into the 

water, and in the south basin it continues underwater to the maximum depth 

of 1470 m, which is reached just 4 km offshore. Only at the northern and 

southern ends is the underwater slope moderate, and even in these places 

the 100 m contour is reached inside 10 km. The adjacent mountain 

ranges exceed 3000 m asl at the northern end of the lake, which is fed by 

several large rivers, and countless small streams which enter all round its 

periphery, in Zambia, Tanzania, Burundi and Zaire. The Ruzizi River, 

draining Lake Kivu, descends the Panzi Falls before entering Lake

Tanganyika so that the two lakes are faunally isolated. The Ruzizi has 

formed a substantial delta at the north end of Lake Tanganyika. The other 

principal affluent is the Malagarasi River, which drains much swampy 

land to the south of Lake Victoria. The lake drains from the middle 

western section via the Lukuga River to the Lualaba, but water levels 

fluctuate over long time periods, much as they do in Lake Malawi to the 

south, and these are discussed by Camus (1965). The flora, fauna, 

hydrology, water chemistry and geological history of the lake proper are dealt 

with in detail in section 2.9.4b, Lake Tanganyika. However, brief account of 

the fish fauna, and the lake and delta floras are given here. The flora and fauna 

of the Fizi Plain, at the head of the large bay near Fizi (4°18'S/28°56'E), is 

quite similar to that of the Ruzizi Plain described in the next section. 

Wetland Flora: Ceratophylluni demersum is abundant in the vicinities of 

affluent river mouths, while in the deltas of several rivers Azolla pinnata 

may form immense floating mats, green or red-brown in colour, and there are 

great submerged beds of Myriophyllum spicatum, Najas marina, N. 

pectinata, Ottelia ulvifolia, Potamogeton pectinatus and P. schweinfurthii. 

Potamogeton spp. are the predominant macrophytes around much of the 

shoreline, with occasional rafts of Nymphaea caerulea and N. capensis in 

shallow sheltered bays. Cyperus papyrus, Phragmites mauritianus and 

Typha domingensis dominate the delta swamps, with Vossia cuspidata as 

principal low growing associate. 

Wetland Fauna: The lake contains a large fish fauna, comprising some 

193 species from 13 families, an analysis of which suggests that the lake 

is ancient and has been isolated for a long time. Although 98% of the 

cichlids and 57% of the non-cichlid species are endemic, similar 

proportions to those found in the faunas of Lakes Malawi and Victoria, it 

is the degree of speciation here, which distinguishes Lake Tanganyika from 

the others. It contains no less than 8 endemic genera, and some endemic 

species reveal distinct subspecific forms between the north and south ends 

of the lake. Comparatively recently Zaire Basin species have invaded the 

lake, presumably by way of the Lukuga River, the most recent effluent. 

These include Distichodus fasciatus,Hydrocynus goliath and Labeo 

lineatus. Other interesting species include Protopterus aethiopicus, 

Polypterus congicus and P. ornatipinnis, also Zaire Basin species which 

live in lagoons and deltas around the lake, especially the Malagarasi Delta. 

These are ancient fish and their presence has probably been continuous from 

the time when the Malagarasi flowed directly into the Zaire Basin, before the 

faulting which led to the development of the Rift Valley and its lakes. There 

are two fully aquatic piscivorous snakes in the lake. Boulengerina 

annulata lies up in the rocks during the day and fishes nocturnally, while 

Glypholycus bicolor hunts pelagic fish, chiefly shoals of Stolothrissa

tanganicae. 

Human Impact & Utilisation: The lake is fished intensively from 

several ports including Uvira, Kalemie (Albertville) and Moba 

(Baudouinville) in Zaire. 


(b) The Ruzizi Plain 



Area: 184 000 ha (total lower plain) 

Altitude: 773-810 m as1 

Nearest Towns: Bukavu (47 km N); Kongolo (350 km SW) 

General: The Ruzizi Plain occupies the floor of the Western Rift Valley 

at the northern end of Lake Tanganyika, and has been transgressed by lake 

water in the past. The lower plain slopes very gently southwards to the 

lake, and the Ruzizi River meanders across the centre of the plain, roughly 

from north to south, forming the national border with Burundi. On either side of 

the plain the land rises steeply into the mountains. Precipitation over the lower 

plain is 800-900 mm/yr, while on the slopes of the valley it is 1200-1300 

mm/yr. April is the wettest month with mean falls of 140-160 mm in the plain 

and 180-200 mm in the hills, depending upon site. The dry season usually 

begins in the second half of May and persists until the end of September, but 

is longer in the south than the north. Winds are generally light in the morning, 

increasing to peak velocities at midday, when they may attain 20 km/hr in the 

wet season and 28 km/hr in the dry season. Mean monthly temperatures range 

from 22.5-25°C, while mean monthly maxima and minima are 30.5-32.5°C 

and 14.5-17°C respectively. There are extensive wetlands on the plain, 

chiefly associated with the Ruzizi River and its tributaries. 

Wetland Flora: Phragmites mauritianus swamps accompany the Ruzizi 

River, in a belt up to 3 km wide along the lower half of its 135 km course 

between Lake Kivu and Lake Tanganyika and into its delta, but along its 

tributaries these swamps are reduced to much narrower strips, e.g. on the Sange 

and Kiliba Rivers. The swamps are broader in the south than the north, and it is 

estimated that the area of reedbeds may exceed 20 000 ha. Where inundation is 

permanent the reeds reach 4 m in height, but where it is seasonal they are little 

more than 2 m high. The most important associate species are Ipomoea 

fragrans, Panicum meyerianunz, Paspalidium geminatum and Polygonum 

pulchrum, the last three species being especially well represented where 

the surface waters are ever only superficial. 

On the sides of lakes, on meander bends and around small islands in the river,

one finds sandy beaches, subject to periodic inundation, but with groundwater 

always near the surface. These places are covered by a Cyperus laevigatus- 

Pluchea bequaertii association. There is generally a distinct upper stratum, 

reaching 1.5-2 m, comprising suffrutescent species, dominated by Pluchea 

bequaertii, with P. dioscoridis and P. ovalis, and a ground cover of 

Cyperus laevigatus and Fimbristylis ferruginea reaching 30-125 cm. 

The country adjacent to the floodplain is Themeda-Bulbine grassland, but 

throughout this there are small ponds which provide waterholes for domestic 

cattle. They are flooded to depths of over 1 m in the rainy season but are 

transformed into quagmires during the dry season, and support a flora of 

Oryza barthii, with Asteracantha longifolia and Burnatia enneandra on 

the fringes, and sometimes central patches of Nymphaea lotus and 

Utricularia thonningii. From place to place the Themeda-Bulbine 

association is interrupted, in periodically inundated depressions on the 

lowest terraces, by swards of Sporobolus spicatus which are heavily grazed 

by local cattle in the dry season. This is the most halophilic association on 

the valley floor, under which the soil water contains salts to a total 

concentration of 8%o. Elsewhere, in large shallow depressions in the 

Themeda-Bulbine savanna, where the gradient is virtually nil, water collects 

semi-permanently. The ground surface is always muddy, particularly where 

trampled by cattle, but surface water is seldom more than a few centimetres 

deep. These areas support a cover of Panicum ruziziense, with some 

Ammania senegalensis, Cyperus platycaulis, Desmodium hirtum, 

Ilysanthes parviflora, Lindernia boutiqueana and Ophioglossum 

costatum. 

Another very local hydromorphic association in this large wide valley is that 

of Setaria holstii and Botriochloa insculpta. This occupies depressions 

along the valley floor that were once the beds of lakes. They have clay floors 

and are inundated for most of the wet season, but dry completely during the 

dry season, when the clay hardens and cracks. 

Other species found here include Digitaria scaettae, Glycine borianii 

and Paraknoxia ruziziensis, together with vagrants from the surrounding 

savanna. 

Where the rivers traverse the metamorphic terrain at the feet of the 

mountains they flow in very steep sided valleys, and throughout these 

regions the narrow banks carry gallery forest dominated by Baphia 

descampsii 10-12 m high, with Craibia grandiflora, Cissus araliodes and 

Sterculia tragacantha as typical associates. 

Wetland Fauna: Some reptiles are present, including various swamp

snakes, Dromophis lineatus, Limnophis bicolor and Philothamnus 

irregularis, together with varanid lizards and occasional crocodiles. 

Among the notable birds of the flood plain and permanent herb swamps, 

Actitis hypoleucos, Acrocephalus schoenobaenus, A. scirpaceus, Calidris 

ferruginea, C. minuta, Chlidonias leucoptera, Cuculus canorus, Delicon 

urbica, Falco subbuteo, Glareola nordmanni, Hippolais pallida, Hirundo 

rustica, Motacilla flava, M. feldegg, Pandion haliaetus, Phylloscopus 

trochilus, Porzana porzana, Riparia riparia, Tringa glareola and T 

nebularia may be cited. Mammalian wildlife has been largely displaced by 

domestic cattle, and in numbers, the wetlands now support only small 

mammals, otters, mongooses and water rats. 

Human Impact & Utilisation: Both the Ruzizi Valley and the Fizi Plain 

are intensively cultivated, and the wet areas are frequented by domestic 

cattle in the dry season when large areas of wetland are burned. 


7. Lake Kivu 



Area: c. 260 000 ha (excluding islands; c. 165 000 ha 

in Zaire) Altitude: 1460 m asl 

Nearest Towns: Bukavu (at S end); Kongolo (460 km SW) 

General: Lake Kivu lies in the western trough of the Great Rift Valley, 

enclosed on three sides by land which rises steeply from the lake to over 

2000 m, and to 4507 m just to the north. The lake is 100 km long, and has a 

maximum width of 50 km almost exactly along the parallel 2°S. There are 

several islands in the lake, most small, and most in Rwanda, but Idjwi 

Island, 40 km long and with an area of 30 000 ha, is in Zaire. 

Hydrology & Water Quality: The lake receives run-off from the 

surrounding mountains, and it is believed that warm water is injected into 

the lake from submerged hot springs. Further, effluents from the small 

group of Mokoto Lakes, to the northwest, disappear into the volcanic ash, 

but are believed to reach Lake Kivu. Rainfall in the catchments exceeds 

2400 mm and is not markedly seasonal. The lake is deep, c. 480 m, 

meromictic, and the most firmly stratified lake in Africa. Water density 

increases towards the bottom, but not as a steady gradient; there are a series 

of discrete layers. The surface water has a salinity of 1%o, and the top 70 

metres are mixed, but it seems that below this the hypolimnion is 

completely stagnant, highly saline, and very rich in nitrogen and 

phosphorus. The pH of the surface waters is about 9.1. It appears that

natural phenomena, other than earth movements and the pouring of hot 

lava into the lake, do not cause upwellings of the bottom water, which is 

highly nutritive but contains much dissolved sulphide and methane. The 

temperature at the surface is close to 25°C, decreasing with depth to about 

22°C at 70 m, but then increasing again to 25°C at 375 m depth. The 70 m 

contour is very close to the shore, and since only the upper 70 m of the 

water column is oxygenated, it has been estimated that only 12% of the 

lake floor receives any oxygen. This is the most saline lake in the Western 

Rift Valley. 

Wetland Flora: There is little information regarding the phytoplankton, but 

it is neither diverse nor abundant. The macrophyte flora, which extends 

down to a depth of 8 m, is extremely poor, and there is only a narrow 

fringe of lake bottom above this depth. The deep lake floor is covered by 

an organic ooze, but towards the shores the bottom is quite sandy, with an 

encrusting calcareous scale. Here Cladophora sp. is the dominant plant. 

Higher up there are beds of Ceratophyllum demersum, Najas marina and 

Potamogeton pectinatus, the latter species being most abundant. Around 

the shallowest margins there are beds of Phragmites mauritianus and 

species of Cyperus and Scirpus. 

Wetland Fauna: The fish fauna is poor, comprising just 16 species. Of 

these, 3 also occur in Lake Tanganyika, namely Barbus serrifer, Barillus 

moori and Clarias mossambicus. The first and last have wide distributions, 

but Barillus moori is found only in these two lakes. There are 6 species of 

Haplochromis, all endemic, and a distinct subspecies of Oreochromis 

niloticus ssp. regani, which suggests that speciation has occurred in the 

lake over the last 20 000 years. There is no large predatory species in the 

lake. Birds and otters are the principal piscivores, and the lake supports 

many birds of passage. 

Human Impact & Utilisation: Limnothrissa miodon was introduced 

some years ago, and a small sardine fishery has developed, but prior to 

this there was no commercial fishery of significance. 

Conservation Status: Unprotected. The high mountain catchments to the 

north however, are protected in the Virunga National Park. 

8. Lake Edward 


Coordinates: 0°05'- 0°56'S/29° 16'-29°56'E 

Area: c. 234 200 ha (170 450 ha in Zaire)


Nearest Towns: Lubero (28 km W); Bukavu (225 km SSW) 

General: Lake Edward is 76 km long with a maximum width of 39 km. It 

is connected to Lake George, effectively a bay of Lake Edward, by the 

Kazinga Channel, 40 km long and less than 1 km wide. Lake Edward 

reaches a maximum depth of 112 m, just 5 km from the western shore, 

above which the land rises precipitously to a high plateau over 2000 m asl 

carrying mountain peaks over 3000 m. By contrast the lake floor slopes up 

gradually to the Uganda shore. 

Hydrology & Water Quality: Lake Edward has numerous affluent 

streams, the most important being the Nyamugasani River from the 

Ruwenzori Mountains and the Ishasha, Rutshuru and Rwindi Rivers from 

the Virunga Volcanoes and the Rwanda Highlands. Further inflow comes 

from Lake George, which also drains the Ruwenzori Range and to the 

east shares a watershed with Lake Victoria. However, flow through the 

Kazinga Channel is very sluggish, along a remarkably gentle gradient of 

1:80 000 over the first 24 km. The junction of the waters between Lakes 

Edward and George, indicated by a change in colour, but also in chemistry, 

can usually be seen in the Kazinga Channel. The position of this boundary 

oscillates up and down the channel over a distance of about 3 km 

seasonally. Lake George is fresh, and its water chemistry is known to 

have remained fairly constant over the last 40 years, suggesting that the 

residence time of water in the lake is short, and that evaporation does not 

lead to the concentration of solutes. However, no subterranean outlets are 

known, yet the flow into Lake Edward appears minimal. Precipitation 

over Lake Edward is only 500-650 mm/yr, the lowest in Zaire, but is much 

higher in the adjacent mountains, e.g. approaching 3000 mm/yr on the 

western slopes of the Ruwenzori Massif, the highest in Zaire. Lake Edward 

discharges into the Semliki River, and thence to Lake Albert and the Nile. 

Water spills over a rock shelf at the northern extremity of the lake, which 

functions as a natural weir. Water leaving the lake has a temperature of 

25-26°C and a pH close to 9.1. The lake is more saline than Lake Albert 

and less saline than Lake Kivu. 

Wetland Flora: Potamogeton pectinatus is the dominant submerged 

macrophyte, in association with Najas marina and Vallisneria aethiopica. 

Some Potamogeton schweinfizrthii and Najas pectinata occur along the 

eastern shores. Vallisneria and Najas are best developed in the vicinity of 

river mouths where waters are better aerated. Cyperus papyrus and 

Phragmites mauritianus form swamps at the mouths of effluent streams, 

which are especially well developed along the southern shore. Riverine 

swamps extend back from the lake up all three principal rivers entering the 

southern end of the lake for distances of several kilometres.

Wetland Fauna: The present fish fauna comprises about 23 cichlids and 

30 non-cichlid species. However, the fauna is impoverished, with certain 

widespread families being entirely absent, e.g. Centropomidae, 

Characidae, Malapturidae, Mastacembalidae, Mochokidae and 

Schilbeidae. Further, Citharinus, Distichodus, Hydrocynus, Polypterus 

and Lates, which are found in Lake Albert and the Nile, are also absent, 

although both Hydrocynus and Lates are known to have been present in 

the middle Pleistocene. From palaeontological studies a picture emerges of 

Lake Edward being in a phase of recolonisation, its fauna having been 

partially eliminated at least twice during the late Pleistocene. 

Although the lake once contained crocodiles, as well as the Nile fish cited, 

they are also now absent. The rapids prevented their re-introduction from 

the lower Semliki where they persisted until the middle of this century 

before they were finally eliminated by hunters. However, it appears that 

fish have entered from the east, where there is now a watershed with Lake 

Victoria, and have begun speciating. In the cichlid fauna there are several 

species with close relatives in Lake Victoria, e.g. Haplochromis guiarti, 

H. ishmaeli and H. macrops and two common species, 

Astatoreochromis alluaudi and Haplochromis nubilis. Two species 

present in the Nile have either re-entered or survived, Bagrus docmac 

and Oreochromis niloticus. Oreochronzis leucostictus is confined to 

Lakes Edward and Albert, perhaps having originated in Lake Edward, 

and passed downstream. Considering the history of the lake the 

invertebrate fauna is surprisingly rich. 

The avifauna of the lake and associated river valleys and swamps is very 

diverse and includes herons, ibises, egrets, bitterns, ducks, geese, darters, 

cormorants, skimmers, shoebills, openbills, ospreys, gulls, francolins, 

warblers and weavers. Large numbers of pelicans frequent the lower 

Rutshuru River. Species of interest include Acrocephalus 

schoenobaenus, A. scirpaceus, Anas querquedula, Ardeola ralloides, 

Calidris ferruginea, C. minuta, Charadrius hiaticula, Chlidonias 

leucoptera, Gelochelidon nilotica, Hirundo rustica, Philornachus 

pugnax, Riparia riparia, Tringa glareola, T. nebularia and T 

stagnatilis. 

Human Impact & Utilisation: Relatively little since the proclamation of 

the national park in 1969, but illegal fishing and poaching on the lower 

Rutshuru are chronic problems. Growing tourism could prove a threat, 

and the proposal to dam the Rutshuru River would almost certainly have 

a major, and adverse, impact upon the riverine wetland ecosystem. 

Conservation Status: The entire Zairean section of the lake is protected in

the Virungas National Park, as is the lower course of the Rutshuru and 

several other tributary rivers. 

9. The Semliki River Valley 


Coordinates: 1°20'N- 0°11 ' S/29°30 ' -30°30 'E 

Area: c. 375 000 ha 


Nearest Towns: Bunia (25 km N); Bukavu (300 km SSW) 

General: The Semliki loses 293 m of altitude over its 150 km course from 

Lake Edward to Lake Albert. The upper course is swift, rocky and boulder 

strewn, 30-40 m wide, and enclosed by the dense Ituri Forest. Most of the 

descent is made over two rapids sections in this part of the river. In places 

the river is confined to a narrow channel, 10 m wide, between sheer rock 

walls. On emerging onto the savanna covered, lower Semliki Plain, the 

river flows slowly, eventually meandering to its delta in Lake Albert. A 

chain of oxbow lakes to the west of the present lower course, and deltaic 

deposits in Lake Albert, indicates that the river bed has been moving 

eastwards over the lower plain. Swamps occupy an area 15 km wide and 

3.5 km deep along the southern shore of Lake Albert astride the delta of 

the Semliki, which projects a further 3 km into the lake. Upstream, 

seasonally inundated land extends back from these swamps in a belt 3-7 

km wide for many kilometres, and a large area, centred upon the oxbows 

of the abandoned river course, is poorly drained and comprises 

hydromorphic soils. Farther back upstream, smaller swamps occur along 

the Semliki at numerous isolated sites, mostly where tributaries enter the 

mainstream. 

Wetland Flora: Cyperus papyrus and Phragmites mauritianus 

dominate the riverine and delta swamps, reaching heights of 5 m. Much of 

the unflooded lower valley floor is covered by Themeda savanna, and in 

this, saline hydrornorphic soils support vast swards of Sporobolus spicatus. 

Elsewhere, seasonally inundated soils are covered by species of 

Hyparrhenia, Loudetia and Pennisetum, with Pennisetum purpureum and 

Imperata cylindrica representing post-cultivation grasses. The former 

occurs on the wettest soils, the latter on drier fringes subject to fires. 

Gallery forests contain a spectrum of typical Zaire species, together with 

some of more East African affinity. 

Wetland Fauna: The fish fauna is alluded to in sections 8 and 10. Among 

the reptiles, crocodiles are believed to have become extinct in the region 

as a consequence of intensive hunting, but varanid lizards are common, as 

are snakes. These include Dromphis lineatus, Limnophis bicolor, Naja

sp., Natriciteres olivacea, Philothamnus irregularis and Psammophis 

olivacea in the swamps, and various arborescent species, including 

Dasypeltis scabra, Dispholidus typus, Dendroaspis angusticeps and 

Thelotornis kirtlandii. 

Birds are prolific and diverse, the spectrum changing abruptly at the 

transition from tropical closed forest to savanna, and finally to marshland 

at the delta. The range of piscivores from the latter sites includes 

pelicans, herons, ibises, egrets, gulls, fishing eagles, ospreys, skimmers, 

darters, cormorants and kingfishers, while the rare yellow papyrus 

warbler, Chloropeta gracilirostris, has been recorded from the lower 

Semliki, together with ducks, geese, moorhens, weavers and a variety of 

other warblers. Species of interest include Buteo buteo, Chlidonias 

leucoptera, Ciconia ciconia, Crex crex, Cuculus canorus, Falco 

subbuteo, Gallinago media, Gelochelidon nilotica, Lanius collurio, 

L. minor, Lymnocryptes mininius, Merops apiaster, Pernis aprivorus, 

Phylloscopus trochilus, Porzana porzana, P. pusilla, Riparia 

riparia, Tringa glareola and T ochropus. 

Mammalian populations along the Semliki River are large and species 

found in these areas include Aonyx capensis , Atilax paludinosus , Ce 

phalo phus sp., Damaliscus lunatus, Dasymys sp., Herpestes ichneumon, 

Hippopotamus amphibius, Kobus ellipsiprymnus, K kob, Loxodonta 

africana, Lutra maculicollis, Osbornictis piscivora, Phacochoerus 

aethiopicus and Syncerus caffer. 

Human Impact & Utilisation: Of recent years this has been slight, but 

poaching of elephants continues, and fishing and tourism are potential 

threats. The proposal to dam the Semliki River will, if implemented, 

have a major adverse impact upon the riverine ecosystems, possibly 

compounding damage done by impounding the Rutshuru above Lake 

Edward. 

Conservation Status: A great deal of the Zairean part of the Semliki 

Valley, including the entire upper forested section, is protected in the 

Virungas National Park. This was established in 1925 as Albert National 

Park, and became the Virungas National Park in 1969. It was designated 

a World Heritage Site in 1979. The park is contiguous with national 

parks and wildlife sanctuaries in Uganda and Rwanda. 

10. Lake Albert 


Coordinates: 1°01'-2°07'N/30°23'-31°26'E

Area: 565 915 ha (247 345 ha in Zaire) 


Nearest Towns: Kisangani (575 km WSW); Bukavu (450 km SSW) 

General: Lake Albert lies between two parallel escarpments in the Western 

Rift Valley, at an altitude of 619 m, with an extreme length of 180 km 

and a maximum width of 43 km. Just under 44% of its surface is in 

Zaire. Its deepest point, 56 m, lies 7 km off the western shore, from where 

the land rises steeply to a high plateau more than 2000 m asl. The lake 

floor slopes gently upwards towards the east, but the eastern escarpment 

rises abruptly just a few km from the east bank in Uganda. The lake is 

subject to violent windstorms which cause the upwelling of bottom 

waters, but even without these happenings, the lake is generally well 

mixed. During calm periods, which frequently occur between November 

and February, a degree of stratification develops and dissolved oxygen 

levels fall, but not deleteriously for the fauna. 

Hydrology & Water Quality: The principal affluent streams are the 

Semliki, which enters at the southern end, and the Victoria Nile, which 

enters very close to the northern end. Both rivers have built deltas into the 

lake. While the Nile carries more water than the Semliki, it has little 

influence on the ecology of the lake, other than to maintain water levels. The 

Nile water is fresh, with a salinity of 0.1700, while the main body of lake 

water, up to 10 km from the delta which the Victoria Nile has built into 

the lake, has a salinity of 6%o and a pH close to 9.0. Lesser streams 

entering the lake from Zaire are, from south to north, the Kisege, Ndrigge, 

Muita, Nyamusiki, Kilowir and Mboge Rivers. However, all these, and 

other small rivers entering from the Ugandan side, are highly seasonal 

and of only secondary importance to the two major rivers. Some 

periodically inundated land occurs around the southern margin of the lake 

in the vicinity of the Semliki River Delta, and also along the eastern shore 

at some isolated spots, notably the Victoria Nile Delta. The results of 

detailed hydrobiological surveys were published by the Institut Royal des 

Sciences Naturelles de Belgique (Brussels) between 1957-1962. General 

information is provided by Bishop (1965; 1969) and Livingstone (1976). 

Wetland Flora: Potamogeton schweinfurthii is the dominant submerged 

macrophyte over most of the lake, by contrast with Lakes Kivu and 

Edward where P. pectinatus is most common. However, this latter species 

is also present in Lake Albert. The principal associate species are Najas 

marina and Vallisneria aethiopica, and as in the other lakes, they are 

most abundant in the vicinities of river mouths, but this phenomenon is 

not so pronounced as it is in the two other lakes, possibly because Lake 

Albert is shallower and its waters are generally well oxygenated. In the 

river deltas, there are extensive stands of Cyperus papyrus and

Phragmites mauritianus, the flowering cuims of which reach 4.5 m in 

height, with aquatic meadows of Vossia cuspidata on the lakeward side, 

and twining thickets of Cyclosorus striatus on the landward side. In 

ponds in the swamps, and in sheltered coves around the lake, there are 

floating-leaved and free-floating associations, notably a Lemna 

paucicosta-Pistia stratiotes-Azolla nilotica association, and a Nymphaea 

calliandra association. In the latter, Najas marina, Nymphaea lotus and 

Vallisneria aethiopica are usually to be found, together with free-floating 

plants of Ceratophyllum dentersunt and Utricularia thoningii. Species 

of Nitzschia and Stephanotis are the chief planktonic diatoms, 

undergoing periodic fluctuations in density. Blooms of the blue-green 

alga, Anabaena sp., occur locally from time to time, and lead to the mass 

mortality of fish, especially Lates niloticus. 

Wetland Fauna: The fish fauna comprises 46 species, of which 22 are also 

found in the Nile. Some genera, e.g. Bagrus, Heterobranchus and Lates, 

have long histories in the lake, having been recognised from mid- 

Pleistocene sediments, while Clarotes, which was present in the 

Pleistocene, is no longer there. Alestes baremose, Citharinus citharus, 

Lates niloticus and Oreochromis niloticus form the basis of the present 

fishery. Two distinct populations of Lates niloticus are present, one 

which breeds in the lake, and another which migrates into rivers to 

spawn. In Lake Albert this species is an inshore form and is largely 

piscivorous, whereas another species, Lates microphthalmus, is pelagic 

and feeds mainly on Caradina (a freshwater prawn). Among the other 

piscivores both Hydrocynus vittatus and the smaller H. forskalii occur in 

the lake, but the latter, here, tends to be pelagic and also feeds very largely 

upon Caradina. Of 36 non-cichlid species, 3 are endemic, while of 10 

cichlids, 4 are endemic. These are all species of Haplochromis. The cichlid 

fauna is poor compared with that of most other East African Lakes, including 

some other `nilotic' lakes, such as Lake Edward. Accounts of the fish fauna are 

given by Worthington (1929) and Holden (1967; 1970). The invertebrate fauna 

is discussed by Green (1967a,b; 1971) and Verbeke (1957a,b). 

Birds of interest found along the lakeshore are Buteo buteo, Chlidonias 

leucoptera, Ciconia ciconia, Crex crex, Cuculus canorus, Gallinago 

media, Gelochelidon nilotica, Lanius collurio, L. minor, Lymnocryptes 

minimus, Merops apiaster, Muscicapa striata, Pernis aprivorus, 

Phylloscopus trochilus, Porzana porzana, Riparia riparia, Tringa 

glareola and T. ochropus.

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