No one can deny the fact that the left, right, and center of Ethiopia are endowed with a wide spectrum of fauna and flora that can win the hearts and minds of all and sundry with no trouble. What is more, the Ethiopian highlands consist of wide-ranging streams, rivers, and lakes, and so forth. While on the subject, the Ethiopian highlands that range from Eritrea in the north to Kenya in the south demonstrate diversified features.
It is public knowledge that Ethiopia is endowed with opulent and miscellaneous freshwater eco-regions in the continent. Furthermore, because of the contemporary archetypes of freshwater eco-regions of Africa the freshwater systems of Ethiopia can be expediently positioned under an extensive range of freshwater ecoregions.
Of late, The Ethiopian Herald had a short stay with Abebe Getahun, a Professor of Aquatic Biology at the Department of Zoological Sciences, Addis Ababa University.
As to him, although extensive review work is currently in progress, it appears that a preliminary listing of about 191 valid indigenous species represents what is so far known from Ethiopian freshwaters. There are additionally nine exotic species introduced into the freshwater systems for various purposes.
Of the 191 indigenous species, about 56 species and two subspecies are endemic to Ethiopia. Moreover, the inadequacies of the present study underline the contention that further extensive collections and identifications will raise both the total number and the number of endemic species of the country.
The massifs of Ethiopian plateau ascend precipitously from the Nile lowland. Its highlands are divided into two parts by the East Rift Valley. Aside from receiving about 950 mm or more rainfall by reason of a dual-route of the inter-tropical conjunction zone, they are assisted by the lie of the land with the high mountains east of Lake Abaya.
The freshwater fish fauna of Ethiopia is of particular interest since it contains a mixture of Nilo-Sudanic, East African, and endemic forms. The Nilo-Sudanic forms are represented by a large number of species found in the Baro-Akobo, Omo-Gibe, and Abay Drainage Basins. The southern Rift valley (Lakes Abaya and Chamo), and the Shebele-Genale basins also have elements of these forms.
He stressed that the southern Rift valley (Lakes Abaya and Chamo), and the Shebele-Genale Basins also have elements of these forms. It is believed that these lakes and river basins had former connections with the upper White Nile (through Lake Turkana in the former case) as recently as 7500 years ago.
He further stressed that these Nilo-Sudanic forms are related to West African fishes and this, too, is believed to be due to past connections of the Nile to Central and West African river systems.
The Professor elucidated that the freshwater eco-regions of Africa the freshwater systems of Ethiopia can be expediently touched upon the Ethiopian, Lake Tana itself, Northern, Lake, Shebele Juba catchments, and Red Sea coastal (the Awash system and the saline lakes of northern Ethiopia that includes Lakes Abbe, Afambo, Afdera, and Asale).
He said regarding the Red Sea coastal (the Awash system and the saline lakes of northern Ethiopia that take account of Lakes Abbe, Afambo, Afdera, and Asale), the Awash River ends in a chain of saline lakes of which the largest are Gamari, Afambo, Bario and Abe. These all lie to the east of Asaita. Afambo, with a town of the same name, is about 30 km east of Asaita"
He went on to say, "The Awash enters Lakes Abe and Afambo on their northwestern shores and is the only source of freshwater for these lakes. All the lakes and the woody vegetation around them as well as in the towns are visited by very large numbers of Palaearctic migrants and it is suggested that the whole area be seen together concerning the conservation of the wildlife of the area"
The site is believed to hold more than 20,000 water birds. Good numbers of many wetland congregator species are known to use the area including White-faced Tree Duck, White Pelican, Squacco Heron, Cattle Egret, Little Egret, wood Ibis, and Marabou.
In the same way, the site is also an important staging point on the migration route to and from the Arabian Peninsula used by many Palearctic species both in autumn and in spring. These include Basra Reed Warbler, Nightingale, Sprosser, Redstart, Reed Warbler, etc.
"In the same way, Lake Afdera is located some 700 km north of Addis Ababa (12.6oN and 41oE) at an altitude of 80 meters below sea level. "Afdera" by the local (Afar) language means inaccessible. The depression is under active volcanic and tectonic activities"
The molten black rocks and gravels all around the area and the hot springs that drain the lake, the only source of water other than the scanty precipitation, witness this reality. It is a rainfall deficit area receiving an average annual rainfall of about 100 mm.
Similar is Lake Asale found north of Lake Afdera at an altitude of 150 m below sea level. The other lakes in that region (Gamari, Afambo, Bario, and Abbe) are fed by the river Awash. Three species of fishes were identified from Lake Afdera: Danakilia Franchetti; Aphanius (Lebias) dispar and Aphanius (Lebias) stiassnyae. These fishes inhabit areas where the fresh water from the various hot springs enters into the saline lake water.
The Professor said concerning the Shebele Juba catchments, "The southeastern part of the eastern highlands is drained by the headwaters of the Wabi Shebele and the Fafan, but the mainstream of the Wabi Shebele does not reach the Indian Ocean. The south-western part of the eastern highlands is drained by the Wabi Gestro, the Genale Doria, and the Dawa Parma, which unite into the Juba that drains into the Indian Ocean.
The headwaters of the Juba arise just East of Abaya and Chamo but are separated from the lake drainages by a high mountainous divide.
He elucidated that most of the Nilotic species found in Lake Abaya, with the exception of Hyperopisus bebe, are present in the Wabi Shebelle-Juba drainage and the Omo-Rudolph drainage. Somalia is all desert or semi-desert. The only large perennial rivers are the Wabi Shebelle and Juba, which arise on the eastern slopes of the Ethiopian highlands and flow across the southern part of the country.
Primary division fishes living away from these rivers are subterranean midway between the lower courses of the Wabi Shebelle and the Juba, where they are widest apart; there is a low-lying limestone plateau with extensive underground waterways radiating out from it. These are inhabited by the endemic genera Uegitglanis and Phreatichthys.
"The geographically nearest surface-dwelling populations of Barbus sp. are in the Wabi Shebele, over 250 miles distant. There is no evidence, either from the distribution of living fishes or the fossil record that the Nilo-Sudanic fish fauna formerly extended into the Eastern rift valley south of Lake Turkana. The Juba and Wabi Shebele are the only rivers on the East coast of Africa having Nilo-Sudanic fishes in any numbers." he wrapped up.