Sustainable Highland Rivers Management in Ethiopia

DELIVERABLE 1.3 Top‐down operative stream classification system (typology) for Ethiopian highlands

Deliverable No. 1.3

Authors

Aschalew Lakew Haile, EAIR‐NFALRC Otto Moog, BOKU

Suggested citation: Haile, A.L. & O. Moog (2016): LARIMA. Deliverable 1.3: Top‐down operative stream classification system (typology) for Ethiopian highlands. Appear‐ Austrian Partnership Programme in Higher Education & Research for Development.

Document title: Top‐down operative stream classification system (typology) for Ethiopian highlands

Work Package No.: 1

Document Type: Intern Deliverable

Date: 23.06.2016

Document Status: Version 2

Acknowledgements

This project has received funding from APPEAR ‐ Austrian Partnership Programme in Higher Education & Research for Development. APPEAR is a programme of the Austrian Development Cooperation and is implemented by the OeAD.

Authors would like to thank all of the individuals, whose names are not mentioned as main contributors, but have contributed by providing comments and photos to this deliverable. Photos used with permission of the copyright holder.

Deliverable No. 1.3

Content

1 Introduction ...... 2 2 Ethiopian eco‐geographical features ...... 2 Altitude ...... 2 Geology ...... 3 Hydrogeology ...... 3 Hydrology ...... 4 Rainfall in Ethiopia ...... 5 Temperatures in Ethiopia ...... 6 Soil types ...... 7 Land cover ...... 7 Agro‐ecological zones of Ethiopia ...... 8 3 Bio‐geographic classifications applicable for river management ...... 9 Freshwater Ecoregions of the World (FEOW) ...... 9 Detailed description of the FEOW freshwater ecoregion of Ethiopia ...... 10 3.2.1 Lake Tana (526) ...... 10 3.2.2 Northern Eastern Rift (528) ...... 12 3.2.3 Upper Nile (522) ...... 15 3.2.4 Ethiopian Highlands (525) ...... 16 3.2.5 Lake Turkana (530) ...... 18 3.2.6 Horn of Africa (529) ...... 21 3.2.7 Lower Nile (523) ...... 23 3.2.8 Shebelle – Juba (531) ...... 26 4 Terrestrial ecoregions ...... 29 5 Other Ethiopian regional typologies ...... 44 Ecosystems of Ethiopia ...... 44 6 African subregions by Barber‐James & Gattolliat ...... 47 7 Proposed river typology based on ecoregions and eco‐geographic features of Ethiopia ...... 48 Examples of stream typology ...... 49 8 Preliminary bottom‐up validation of proposed typology ...... 53 9 References ...... 57

Deliverable No. 1.3

1 Introduction

Biodiversity is not spread evenly across the Earth but follows complex patterns determined by climate, hydrology, geomorphology, geology, soil composition, land‐use, vegetation, ecology and the evolutionary history of the planet. The use of a typology to classify streams has become an accepted prerequisite of ecological assessment (Hering et al., 2004). A typology generalizes knowledge that can be applied on a wider scale and improves the comparability of running waters in management, assessment, and prediction (Hawkes, 1975).

Stream typology is defined as a large area of land that contains an eco‐geographically distinct assemblage of natural communities that

 share a large majority of their species and ecological dynamics  share similar environmental conditions, and  interact ecologically in ways that are critical for their long‐term persistence

Frey (1977) stated that there are recognizable regions within which particular patterns are observed. These regions generally exhibit similarities in the mosaic of environmental resources, ecosystems, and effects of humans, and can therefore be termed “ecological regions” or “ecoregions”. Ecological regions are seen as areas of relative homogeneity in ecological systems and relationships between organisms and their environment (similar climate, landform, soil, potential natural vegetation, hydrology, or other ecologically relevant variables) (Omernik, 1987).

In recent years there has been an increasing awareness that these ecoregions exist and effective management of environmental resources must be undertaken with an ecosystem perspective (Omernik, 1995; Moog et al., 2004). Consequently it became apparent in the early 1980 in the US, the early 1990s in Australia and the late 1990s in Europe that administrative regions were no longer a satisfactory basis for water management planning, monitoring and assessment. The use of ecoregions or bioregions in water management and conservation is widespread nowadays on many continents, e.g. the Global 200 ecoregions (WWF), American ecoregions (Omernik, 1987), Australian bioregions (Thackway & Cresswell, 1995), African ecoregions (Kleynhans & Hill, 1999) and European ecoregions (Water Framework Directive, 2000).

Deliverable No. 1.3

2 Ethiopian eco‐geographical features

Altitude

The topography of Ethiopia is highly diverse, with elevation ranging from 125 m below sea level at the Denakil Depression to 4620 m a.s.l. at Ras Dejen. More than 45% of the country is dominated by a high plateau with a chain of mountain ranges divided by the East African Rift Valley. A geographic region with elevations greater than 1500 m is known as the highlands where 90% of the nation’s population resides, and a region with elevation less than 1500 m a.s.l. is known as lowland. This large diversity of terrain has led to wide variations in climate, soils and natural vegetation. Elevation is an important element in determining the climate of Ethiopia. For every 1000 m, the temperature drops about 6.5 degrees Celcius. Ethiopia has five climatic zones defined by altitude and temperature:

1. Hot, arid zone below 500 m, where average annual rainfall is less than 400 mm and average annual temperatures range between 28°C and 34°C or higher; 2. The warm to hot, semi‐arid zone includes those areas with an altitude of 500–1,500 m, average annual rainfall generally of around 600 mm (but as high as 1,600 mm in the western lowlands of Gambella) and an average annual temperature range of 20–28°C; 3. The warm to cool, semi‐humid zone covers the temperate highlands between 1,500 and 2,500. Average annual temperatures vary between 16°C and 20°C, and annual rainfall is generally around 1,200 mm, reaching 2,400 mm in the south‐west; 4. The cool to cold humid zone includes the temperate highlands between 2,500 and 3,200 m, where average temperatures range between 10°C and 16°C, with an annual rainfall of 1,000 mm and up to 2,000 mm in higher areas; 5. The cold, moist temperate zone covers the Afro‐alpine areas on the highest plateaus between 3,200 and above; average temperatures are below 10°C and annual rainfall averages less than 800 mm.

Figure 1: Distribution of Ethiopian highlands across 12 drainage basins

2

Deliverable No. 1.3

Geology

The Ethiopian region records about one billion years of geological history. The fantastic scenario is the country is result of geodynamic and geomorphic processes which have shaped this territory since the Oligocene.The dominant igneous volcanic rock in the highlands of Ethiopia may create similar chemical characteristic in water draining through it. A short characteristic of the geological situation is given in the chapter “Hydrogeology”).

Figure 2: Major geology of Ethiopia Hydrogeology

The most important aquifers in Ethiopia are formed by unconsolidated quaternary sediments; Tertiary‐quaternary volcanic rocks; and Mesozoic consolidated sedimentary rocks. Basement aquifers are also important locally. The interaction between surface, subsurface and base flow with different geology have impact on the stream and river water quality which can influence the biodiversity.

3

Deliverable No. 1.3

Figure 3: Major hydrogeology of Ethiopia Hydrology

Most hydrological records in Ethiopia started in the 1960s following the initiation of the Blue Nile Basin Master Plan study by the USBR (United States Bureau of Reclamation). The country has 12 drainage basins (8 river basins, 1 lake basin and 3 dry basins) originated from the highlands with the total annual surface runoff about 122 billion cubic meters and causes about 3 billion tons of top soil erosion per year. Ethiopia is often referred to as the ‘water tower’ of horn of Africa mainly because of its wide variety of landforms and climatic conditions, creating an extensive river network system throughout the country. Despite the huge water resource in the country, very small amount has been developed for agriculture, hydropower, industry, water supply, fishery and other purposes.

Table 1: Short description of the twelve basins of Ethiopia

River basin Source Catchment (km²) Direction of flow Annual runoff (BM3) Abay (R) West, South ‐ west highlands 199,812 West to Sudan 52.6 Wabeshebele (R) Bale highlands 202,220 East to Somalia 3.16 Genale (R) Bale highlands 171,042 East to Somalia 5.88 Awash (R) Central highlands 112,696 North east to Djibouti 4.6 Tekeze (R) North Wello highlands 82,350 West to Sudan 8.2 Omo‐Gibe (R) Central, Western highlands 79,000 South to Kenya 17.6 Baro‐Akobo (R) Western Highland 75,912 West to Sudan 23,6 Rift valley (L) Central and Arsi highlands 52,739 Internal 5.6 Mereb (R) Adigirat highlands 5,900 North‐west to Eretria 0,26 Ogaden(D) ‐ 77,120 East ‐ Denakil (D) North Wello highlands 64,380 East 0.86 Aysha (D) ‐ 2,223 East ‐ Source: Modified from Integrated River Basin Master Plan Studies (MoWR, 1998) D= Dry basin R= River basin, L= Lake basin

4

Deliverable No. 1.3

Figure 4: Drainage basins of Ethiopia

Rainfall in Ethiopia

According to the National Meteorological Services Agency, the highest mean annual rainfall over 2,400 mm, is in the south‐western highlands. The amount of rainfall gradually decreases to about 600 mm in the north in areas bordering Eritrea, and it drops to less than 100 mm in the north‐east in the Afar Depression, and to around 200 mm in the south‐east in the Ogaden Desert. The mountain areas over 3,500 m frequently receive snow and hail, but it usually melts within hours after it falls.

Figure 5: Annual rainfall distribution in Ethiopia

5

Deliverable No. 1.3

Based on this rainfall distribution pattern, the following four major rainfall regimes can be distinguished:

1. Central, eastern and northern areas of the country experience a bimodal rainfall pattern, receiving the majority of their rainfall from the Atlantic, while some derives from the Indian Ocean. The big rains from June to September come mainly from the Atlantic, while the light spring rains between February and May come from the Indian Ocean. 2. Western and south‐western parts of the country experience a unimodal rainfall pattern brought about by wind systems coming from the Indian Oceans and merge with those from the Atlantic to give continuous rain from March or April to October or November. The amount of rainfall and length of the rainy season decreases from south to north. 3. Southern and south‐eastern parts of the country experience a bimodal rainfall pattern brought about by the wind system coming from the Indian Ocean from September to November and from March to May. The most reliable rainy months are April and May. 4. North‐eastern parts of the country comprise part of the western escarpment of the Pitt Valley and the adjacent Afar depression. The lowlands have only one rainy season during which only a little rain falls. However, the escarpment, particularly in the north, can have a third rainy season brought by moist winds from Asia which have crossed the Arabian Peninsula and cool as they rise over the Ethiopian escarpment. These can bring mist and rain anytime between November and February. Temperatures in Ethiopia

The highest mean maximum temperatures in the country, about 45°C from April to September and 40°C from October to March, are recorded from the Afar Depression in north‐east Ethiopia. The other hot areas are the north‐western lowlands, which experience a mean maximum temperature of 40°C in June, and the western and south‐eastern lowlands with mean maximum temperatures of 35°C to 40°C during April.

The lowest mean temperatures, of 4°C or lower, are recorded at night in highland areas between November and February (National Meteorological Services Agency, 1989; Ethiopian Mapping Authority, 1988). Many of those areas, particularly in valley bottoms, have occasional ground frost.

Figure 6; Mean annual temperature in Ethiopia

6

Deliverable No. 1.3

Soil types

The wide ranges of topographic and climatic factors, parent material and land use have resulted in extreme variability of soils (FAO, 1984). In different parts of the country, different soil forming factors have taken precedence. According to the Ministry of Agriculture about 19 soil types are identified throughout the country. The big proportion of the country’s landmass is covered by lithosols, nitosols, cambisols and regosols in order of their importance. Research showed that Potassium, Nitrogen, Cation Exchange Capacity (CEC) and organic matter contents of most Ethiopian highland soils are generally high by international standards (EARO, 1998), whereas their phosphorous content is low to very low.

Figure 7: Major soil types of Ethiopia

Land cover

Ethiopia's wide ranging altitudes and associated agro‐ecological zones have produced varied landscape and vegetation types, from tropical moist forests (high forest) in the southwest and the Bale Mountains, to desert shrubs in the east and northeast and parkland agroforestry on the southern highlands. Pressures on forestlands from agriculture expansion and wood fuel consumption are likely to increase in the future as the population in Ethiopia is increasing.

7

Deliverable No. 1.3

Figure 8: Land cover of Ethiopia Agro‐ecological zones of Ethiopia

The multitude of agro‐ecological zones (AEZs) of Ethiopia is traditionally classified into five categories with traditional names assigned to each zone, based on altitude and temperature: Bereha, kola, weinadega, dega and wurch. However, the amount of rainfall and its distribution are also important in classifying common agro‐ecological zones. It is common to associate the traditional zones with elevation and temperature and try to recognize agroclimatic and vegetation zones. Many researchers have classified the vegetation and ecological zones (Zerihun, 1999; MoA, 2000). The current AEZ classification (MoA, 2000) is based on the basic ecological elements of climate, physiography, soils, vegetation, farming systems, etc. The intention of better characterization is to suit the country’s diverse but unique natural and cultural diversity. Eighteen major AEZs are delineated and named by terms describing the broad moisture and elevation conditions of areas.

Figure 9: Agro‐ecology of Ethiopia 8

Deliverable No. 1.3

3 Bio‐geographic classifications applicable for river management

Several efforts have been made to delineate eco‐geographic regions such as Eco‐Zones, Ecoregions, Bioregions, and others for the world in general and Ethiopia in particular. The basic grouping into terrestrial or freshwater regions can be seen as a main unit of discrimination. Freshwater Ecoregions of the World (FEOW)

FEOW provides a global biogeographic regionalization of the Earth's freshwater biodiversity. The WWF Conservation Science Program in partnership with The Nature Conservancy and 200 freshwater scientists from institutions around the world under the guidance of Abell (2008) have developed FEOW.

The freshwater ecoregion map encompasses 426 units and delineated based on the best available information. However, data describing freshwater species and ecological processes are characterized by marked gaps and improved information in the future may warrant map revisions.

Ethiopia shares nine freshwater ecoregions of the FEOW system similar to Thieme regions (Thieme et al., 2005). Thieme et al. (2005) can be regarded as a quite prominent zonation outcome among the attempts to delineate freshwater ecoregions. Many authors used freshwater ecoregions in their analysis because they provide appropriate units for representation of distinct species assemblages, habitats, and processes at the continental scale. Their ecoregions delineation took into account aquatic species distributions (with a strong focus on fish, molluscs and herpetofauna) and drainage basins divides. The 10 African ichthyofaunal provinces of Roberts (1975) served as their basis for their bioregion delineation.

Table 2: Classification of freshwater ecoregions in Thieme and FEOW systems

Thieme system FEOW system 3 Lake Tana 526 Lake Tana 4 Northern Eastern Rift 528 Northern Eastern Rift 15 Upper Nile 522 Upper Nile 39 Ethiopian Highlands 525 Ethiopian Highlands 56 Lake Turkana 530 Lake Turkana 83 Horn 529 Horn of Africa 86 Lower Nile 523 Lower Nile 89 Red Sea Coast 527 Red Sea Coast 90 Shebella‐Juba‐Catchment 531 Shebelle ‐ Juba

9

Deliverable No. 1.3

Figure 10: The map provides a detail of the FEOW regions that cover the area of Ethiopia

Detailed description of the FEOW freshwater ecoregion of Ethiopia

3.2.1 Lake Tana (526)

Lake Tana is the source of the Blue Nilelocated in the highlands of Ethiopia lies in the north part of Ethiopia and. The Blue Nile descends from Lake Tana to Tiss‐isat falls isolating the lake’s freshwater fauna from the rest of the Nile.

Main rivers or other water bodies

Lake Tana was formed by a volcanic blockage that reversed the previously north‐flowing river system (Beadle, 1981). The total area of the Lake Tana basin is 16,500 km2 and the lake itself covers about 3,150 km2. Numerous seasonal streams and four perennial rivers feed the lake, while only one—the Blue Nile—leaves it (Nagelkerke, 1997).

The lake is situated in the highlands of Ethiopia at about 1,800 m, and experiences a tropical highland climate.

Air temperatures range widely, between 7 oC to 31oC, whereas water temperatures stay relatively mild, normally between 18oC and 26oC (Nagelkerke, 1997). The dry season lasts from October/November to May/June with maximum monthly rainfall (up to 500 mm/month) in July. Annual rainfall in the vicinity

10

Deliverable No. 1.3

of the lake averages 1315 mm/year, but evaporation is higher at about 1,800 mm/year (Burgis & Symoens, 1987).

Freshwater habitats

Because evaporation exceeds rainfall, the hydrology of this shallow lake depends largely on the local climate (Burgis & Symoens, 1987). Lake level varies depending on seasonal rains. The average difference between the lowest lake level (May‐June) and the highest (September‐October) is 1.5 m (Nagelkerke, 1997). The lake has a mean depth of 8 m, and is well mixed due to relatively strong winds in the evenings (Nagelkerke, 1997). Cyperus papyrus and other Cyperus spp. line the shores of the lake (Beadle, 1981).

Fish Fauna

Fish species in the lake are most closely related to those of the Nilo‐Soudanian biogeographic region. Lake Tana hosts extended cyprinid species flock in Africa. Fifteen species of large barbs have been described from Lake Tana (Nagelkerke, 1997; Nagelkerke & Sibbing, 1998;. The species flock is believed to be less advanced in its evolution than Lake Lanao’s cyprinid flock (Mina et al., 1996). Eight of the large barbs are piscivorous, and Barbus humilis and the newly described small species, Barbus tanapelagius, are thought to be the major prey species (De Graaf et al., 2000). It is likely that the Lake Tana barbs evolved from one ancestral species that probably resembled Barbus intermedius (Nagelkerke, 1997).

About 70% of the fish species in this highland lake are endemic, including eighteen endemic cyprinids. The tilapia (Oreochromis niloticus) of Lake Tana belongs to a widespread species but is described as an endemic subspecies, Oreochromis niloticus tana (Seyoum & Kornfield, 1992). The only river loach (family Balitoridae) known from Africa, Nemacheilus abyssinicus, was described from Lake Tana in 1902 and rediscovered in 1992 in the lake and in the upper Omo River (Dgebuadze et al., 1994).

The large catfish, Clarias gariepinus, widespread throughout Africa, also lives in the lake and forms an important part of the fishery.

The invertebrate fauna is relatively diverse. Fifteen species of molluscs, dominated by the Planorbidae family, have been described, including one endemic. An endemic freshwater sponge, Makedia tanensis, has recently been discovered in the lake. The sponge is small (specimens found were up to about 2 cm), white and of an encrusting form belonging to a monotypic genus (Manconi et al. 1999).

11

Deliverable No. 1.3

Figure 11: Lake Tana freshwater ecoregion

3.2.2 Northern Eastern Rift (528)

Numerous highly productive lakes lie in the Eastern Rift valley that cleaves the eastern and western sections of the high altitude Ethiopian dome and extends from the edge of the xeric, Red Sea Coastal ecoregion in the north to Lake Awassa in the south.

Figure 12: Northern Eastern Rift freshwater ecoregion (red boundary)

12

Deliverable No. 1.3

Main rivers or other water bodies

Two closed basins occur in this section of the Rift Valley: in the south, Lake Awassa basin, consisting of Lake Awassa and the swampy Lake Shallo; and basin in the north composed of a series of four interconnected lakes (Abijata, Langano, Shala and Zwai). There is also a number of hot springs adjacent to the lakes.

This ecoregion also contains a number of crater lakes (Bishoftu, Aranguade, Hora, Kilotes and Pawlo) located at the northwestern edges of the rift valley around the town of Debrezeit (Mohr 1961), at an altitude of about 1,900 m. These lakes lie in volcanic explosion craters produced about 7,000 years ago. The Awash River, which begins in the Ethiopian Plateau, flows north in the Rift Valley and terminates in Lake Abhe, a closed lake near the border between Ethiopia and Djibouti.

The mean annual air temperature of this ecoregion varies with altitude and ranges between 20oC and 22oC (Tudorancea et al., 1999). There is a four‐month dry season from November to February and an eight‐month rainy season from March to October. The main rains occur between July and September.

Freshwater habitats

Five major lakes and several rivers lie within this ecoregion. Lake Zwai, the most northerly lake, is located at an altitude of 1,840m, covers 434 km2 and has average depth of 2.5 meters (Balarin, 1986). Extensive marshes of Papyrus (Cyperus papyrus) border the lake and produce large numbers of mosquitoes (Anopheles pharoensis, A. mauritianus and Taeniorhynchus uniformis), (Omer‐Cooper, 1930). The Makki River flows into the lake from the northwest and the River Kattar flows into it from the northeast. The lake’s waters flow out through the River Bulbula into Lake Abijata.

The three lakes in the chain are Lake Langano, Lake Abijata, and Lake Shala. Lake Langano, located at an altitude of 1,582 m, covers 241 km2, and has a maximum depth of 47.9 m and a mean depth of 17 m. Salinity is 1.88 g per liter (Wood & Talling, 1988). Lake Langano receives most of its water from small rivers that drain from the Arsi Mountains, which make up the eastern wall of the Rift valley. The only outlet from the lake is the Hora Kelo River, which flows into Lake Abijata. Lake Abijata is found at an altitude of about 1,600 m and is an alkaline lake. The shores slope gradually, and are muddy, with areas of Juncus vegetation. The depth is about 10 m, and the bottom of the lake is sandy. Three rivers feed Lake Abijata: Gogessa, Bulbula, and Hora Kelo. Lake Abijata has no outlet, and it loses its water by evaporation only. Lake Shala is the deepest of the Ethiopian Rift lakes, 266m. It is 28 km long and 15 km wide, and is surrounded primarily by Pleistocene volcanic rocks. The eastern and western shores are covered by lacustrine deposits and Holocene sands, occasionally blackened by obsidian detritus (Mohr, 1961). The great depth of Lake Shala may be related to the origin of the basin by intense faulting. Two permanent creeks and several seasonal streams flow into its closed basin.

Lake Awassa is located at an altitude of 1,680 m, lies south of the other lakes in the ecoregion. It has a surface area of 88 km2, a maximum depth of 22 m, and an average depth of 11 m. Lake Awassa is a polymictic lake. The water is murky and alkaline with a pH between 8.75 and 9.05 (Tudorancea et al., 1988). Like Lakes Abijata and Shala, it is a terminal lake without any visible outlet. Its main tributary is

13

Deliverable No. 1.3

the Tikur Wuha River, which drains swampy Lake Shallo. An extensive belt of submergent and emergent rooted vegetation, which extends about 150 m offshore, covers the littoral zone.

The flora varies among the different lakes. Three major groups of algae dominate: Chlorophyceae, Cyanophyceae and Diatomophyceae (Tudorancea et al., 1999). The most common emergent plants are Scirpus spp., Typha angustifolia, Paspalidium germinatum, and Phragmites sp. Nymphaea coerulea and Potamogeton spp. are the dominant species of floating and submerged vegetation. Abijata and Shala Lakes lack aquatic macrophytes.

Terrestrial Habitats

The vegetation to the east and south of Lake Shala is Acacia‐Euphorbia savanna. The most common trees are the woodland acacias Acacia etbaica, A. tortilis, and Euphorbia abyssinica, and bushes of Maytenus senegalensis. Beds of bulrushes and sesbania occur where the hot springs and rivers enter the lake, but most of the shore has steep cliffs.

Fish Fauna

The lakes and streams of the Northern Rift ecoregion support a limited freshwater fauna, including only eight fish, with few endemic species. The fish fauna of Lake Awassa consists of two species of Barbus (B. intermedius and B. cf. amphigramma), the North African catfish (Clarias gariepinus), and Oreochromis niloticus. Oreochromis niloticus is abundant in the lakes and rivers of this ecoregion. No fish are recorded from Lake Shala. Despite their depauperate number of species, the lakes of this ecoregion support most of the fish production of Ethiopia.

Three endemic fish, Barbus ethiopicus, B. microterolepis, and Garra makiensis, inhabit Lake Zwai and its adjacent rivers.Introduced species of Tilapia zilli, Clarias gariepinus, and carps are present in Lake Zwai.

Only thirteen aquatic frogs, three aquatic reptiles, twelve aquatic mollusks, and four aquatic mammals live in or adjacent to the freshwater lakes and streams. There are considerable numbers of pelicans, cormorants, ducks, snipe, stilts, egrets, grebes, ibis, herons, gulls, and darters around Lake Zwai. One endemic frog, Bufo langanoensis, lives along the shores of Lake Langano and its tributaries. Lakes Zwai and Langano also harbor hippopotamus (Hippopotamus amphibius).

During the 1970s and 1980s over 400 species of birds were recorded from the Abijata‐Shala National Park. This park is positioned in one of the narrowest parts of the Great Rift Valley, which is a major flyway for both Palaearctic and African migrants, particularly raptors, flamingoes, and other water birds. Many of these birds stop over to rest and feed within the ecoregion. The shallow waters of Lake Abijatta are remarkably rich in insect life, with large swarms of Corixa in particular, though plankton diversity is low. The zooplankton fauna in the Ethiopian rift lakes is dominated, in terms of biomass, by copepods and cladocerans (Tudorancea et al., 1999).

14

Deliverable No. 1.3

Delineation

This ecoregion is defined by the northern lakes of the Ethiopian rift valley and distinguished by lakes with a distinctive fauna when compared to the more southern rift valley lakes of Chamo and Abaya. The fish fauna in the northern lakes appears to have been derived from Awash and associated rivers, while the fish fauna of the latter is Nilo‐Sudanic. These faunal affinities may be explained by the tumultuous geologic past of the ecoregion, which was exposed to six volcanic events between the Oligocene and the present (Woldegabriel et al., 1990). Analyses of invertebrate and fish fossils found in the sediments of the lakes indicate that Lakes Zwai, Abijata, Langano and Shala were once united into a single freshwater lake draining northward into the Awash River. The present‐day lakes are the result of subsequent tectonic or volcanic activity (Tudorancea et al., 1999).

3.2.3 Upper Nile (522)

The vast swamps of the Sudd are the primary feature of the Upper Nile ecoregion, which is situated mainly in Sudan with smaller areas in the Democratic Republic of Congo, Uganda, and Ethiopia. The ecoregion encompasses the basin of the White Nile River; its major tributaries, the Sobat River and Bahr el Ghazal; Lake Albert; and Lake Albert’s main influent, the Semliki River. The point at which the White Nile joins with the Blue Nile marks the northernmost border of the ecoregion (Rzóska 1974; Dumont 1986).

The southern and highest upstream part of this ecoregion is situated in the Rift Valley. This area is rugged, with mountain peaks over 4,600 m. Further to the north, the topography changes dramatically where the Albert Nile flows into the shallow depression of the Sudd. The depression ranges in elevation between 420 to 380 m asl and stretches for about 600 km from end to end. Most of the depression is flat with a gradient of 0.01% or less, and it is underlain by clay soils (Food and Agriculture Organization, 1997).

The dynamic Sudd wetland, whose size varies substantially in response to seasonal and inter‐annual changes in water input, contains a diversity of habitats and supports a rich aquatic and terrestrial fauna (Rzóska 1974). Water entering the Sudd swamps drains from the hills of the Nile‐Congo watershed divide, the escarpment of the Uganda Plateau, the Imatong Mountains, and the Ethiopian Plateau.

The swamps and floodplains of the Sudd are among the most important wetlands in Africa and support a rich biota. Twenty‐two families and 118 species of fish are known to occur within the Upper Nile ecoregion, including 16 endemics. Cyprinidae is the most diverse family, with Alestiidae, Cichlidae, Mochokidae, Mormyridae, Poeciliidae, and Schilbeidae also represented by high numbers of species. Lake Albert has a Nilotic riverine ichthyofauna comprised of 15 families and 46 species.

15

Deliverable No. 1.3

Figure 13: Upper Nile freshwater ecoregion

3.2.4 Ethiopian Highlands (525)

The highlands extend from Eritrea in the north to Kenya in the south. With a long history of isolation, the Ethiopian Highlands are known to harbour a highly endemic biota.Rivers of the western highlands generally flow towards Sudan, whereas those of the eastern highlands tend to flow towards the Indian Ocean.

Water bodies

In the northwestern part of the highlands, the deep, steep‐sided valleys of the major rivers separate blocks of mountains, and the upper courses of the big rivers such as the Tekezze and Abay (Blue Nile) plunge through deep gorges. This part of the Ethiopian highlands is also the source of the headwaters for the Blue Nile. The Blue Nile watershed is the largest basin in Ethiopia. Rivers of this basin drain the great central plateau and the Blue Nile descends about 1,450 m in a distance of only 350 km from its source to Khartoum. The westward flowing rivers (the Tekezze, Angereb, Atbara, Abay, Baro and Akobo) form part of the Nile drainage basin. Three major highland lakes, Lakes Hayq, Ardebo and Ashengie, lie near the edge of the western escarpment of the rift valley at altitudes between 2,000 and 2,500 m. Lake Hayq, located in northern Ethiopia’s Wollo region, has an area of 5 km2 and a maximum depth of 23 m, and is noteworthy for its extremely clear water (Kebede et al., 1992). Lake Ardebo is located about 5‐km southeast of LakeHayq. This lake is smaller in size than Lake Hayq and flows into Hayq via the Anchercah River (Kebede et al., 1992). Lake Ashengieis located north of Lake Hayq in the Tigray region, and sits at an altitude of 2,460 m. The lake covers an area of 25 km2 with a maximum depth of 20 m and a mean depth of 14 m (Wood & Talling, 1988). The lake is fed by a number of small streams from the surrounding areas and there is no drainage out of the lake. According to Westphall (1975), uplift of the Ethiopian highlands together with Arabia occurred on an extensive scale after the regression of the Red Sea towards the southeast in the late Mesozoic to early Tertiary. The Great Rift Valley bisects the highlands into the eastern and western massifs, which are surrounded

16

Deliverable No. 1.3

by escarpments. This ecoregion contains about 70% of Africa’s highlands. The highest peak, Ras Dejen (Dashan) at 4,620 meters, is in the northern Ethiopia. The southeastern portion of the Ethiopian Highlands includes the Sidamo, Bale, Arsi and Harerge Mountains. The highlands in this region are made up of volcanic rocks, and deep river cuts expose crystalline rocks (Ethiopian Mapping, 1988)

The Ethiopian highlands receive about 950 mm or more of rainfall due to a double passage of the intertropical convergence zone. The high mountains east of Lake Tana and the southwestern mountains stand out as places of higher rainfall. They receive 2,000 mm or more of rainfall each year (Westphal, 1975). A rainfall regime that peaks in March‐May and June‐August is typical for the Ethiopian Highlands.

Figure 14: Ethiopian highlands freshwater ecoregion

Fish

The fishes of the high mountain torrential streams are largely cyprinids (Harrison, 1995; Getahun & Stiassny, 1998) adapted to the swiftly flowing floodwaters that occur seasonally. Two genera of fishes (Barbus and Garra) dominate the fish fauna of these streams. Clarias gariepinus, Varicorhinus beso and Labeo spp. are also found in high numbers. The Baro‐Akobo basin is apparently particularly rich in fish diversity (Golubtsov et al., 1995). The fauna is Nilo‐Sudanic and is dominated by Alestes, Bagrus, Barilius, Citharinus, Hydrocynus, Hyperopisus, Labeo, Malapterurus, and Mormyrus genera.

Endemic fishes

Endemism appears to be high among fish, but the fish fauna is not well known. Endemic fishes of the genus Garra (e.g. G. dembecha, G. duobarbis and G. ignestii) have recently been described (Getahun, 2000). Lake Hayq is believed to have no indigenous fish species, although the presence of Clarias gariepinus has been reported (Kebede et al., 1992). Nemacheilus abyssinicus is an endemic species found in the Baro‐Akobo drainage basin, the Omo‐Gibe drainage basin, and Lake Tana.

17

Deliverable No. 1.3

Other aquatic biota

The invertebrate fauna is less well known than the fishes and it is difficult to estimate endemism among the aquatic invertebrates. Harrison and Hynes (Harrison & Hynes 1988) indicated that Dugesia spp., Baetis harrisoni, Pseudocloeon sp., Centroptilum sudafricanus, Afronorus peringueyi, Neoperla spp., Hydropsyche sp., Simulium spp., nymphs of Aeschna, and chironomid larvae dominate the benthic communities in the stony runs and torrents of the Ethiopian highlands. Compared to other highland ecoregions, the Ethiopian Highlands support a rich aquatic mollusc fauna with over 20 species described.

Delineation

Despite the fact that the Ethiopian highlands are presently separated from both the East African and the South Arabian mountains, the riverine fauna resembles that of east and southern Africa (Tudorancea et al. 1999), along with some elements of the Arabian Peninsula. Cyprinids are the dominant fish in the rivers of this ecoregion. For example, it is known that some smallBarbus species (e.g., Barbus paludinosus, B. trimaculatus and B. radiatus) have widespread distributions extending from South Africa to East Africa and into the highlands (Skelton et al., 1995). There are also fish groups (e.g. Garra) common to the Ethiopian highlands and the Arabian Peninsula. These fish groups are estimated to have originated in the Lower Tertiary or late Cretaceous, before the separation of India and the Arabian Peninsula from continental Africa (Briggs 1987); whereas the Red Sea is believed to have separated the African continent from the Arabian Peninsula in the early Tertiary, between the Eocene and Oligocene epochs(Getahun, 1998).

Historically, few scientific studies have been made on the fauna of the river systems of Ethiopia; however, two recent studies have elevated the level of data available for the fish of this ecoregion (Getahun & Stiassny, 1998; Golubstov et al., 2002). River systems in the Tekezze‐Angereb basin have not been studied at all due to security problems in the past. Preliminary reports indicate that the large river bodies of this basin support a rich fish fauna and research is needed to confirm this. Some information on the benthic fauna of Ethiopian mountain streams and rivers is available in Harrison and Hynes (1988).

3.2.5 Lake Turkana (530)

The Lake Turkana ecoregion reaches north to include Lakes Abaya and Chamo, as well as the headwaters of the Omo River southwestern Ethiopia.

Lake Turkana is the largest lake in the eastern portion of the Rift Valley and the fourth largest lake by volume in Africa (Beadle 1981). Lying in a low closed basin at approximately 365 m asl, the lake is situated primarily in northwestern Kenya, with its northernmost end inside Ethiopia. Of the twelve principal rivers that feed Lake Turkana, the River Omo is its only perennial tributary, supplying over 90% of the lake’s inflow (Beadle 1981). The Omo River drains the southwestern portion of the Ethiopian Massif and flows through the Rift Valley into Lake Turkana. Of the seasonal rivers that flow

18

Deliverable No. 1.3

into the lake, the Turkwell and Kerio Rivers are the largest contributors and enter the lake along its western edge and in its southern half (Hughes & Hughes, 1992).

Lake Abayaand LakeChamoare located in the northeastern portion of the ecoregion. Five major rivers feed Lake Abaya, the most important of which is the Bilate. During the rainy season, overspill from Lake Abaya is carried to Lake Chamo via the Ualo River (Hughes & Hughes, 1992).

The Ethiopian Rift Valley has a mean annual rainfall of 600 mm/year, receiving at least fifty percent of the precipitation between July and September. The western foothills of the Ethiopian Rift escarpment receive as much as 800‐1,000 mm of rainfall per year. This heavy rainfall causes the Omo River to flood (June through September), bringing nutrient rich waters into Lake Turkana (Beadle 1981).

Freshwater habitats

Lake Turkana is 260 km long, with an average width of 30 km, a mean depth of 31 m, and a maximum depth of 114 m. It has an area of approximately 7,560 km² and a volume of 237 km³ (Coulter et al., 1986). With no surface outlet, the water budget of the lake is a balance between river and groundwater inflow and evaporation. Evaporation rates are high, at around 2.3‐2.8 m/yr. An influx of about 19 km3/yr is required to keep lake levels steady, and high inter‐ and intra‐annual fluctuations in water level occur as a function of the rainfall in distant upland Ethiopia. Generally, the lake level fluctuates annually with an amplitude of about 1‐1.5 m, but it also undergoes considerable long‐term variations that exceed those of any other lake of natural origin (Butzer, 1971). The mean retention time of water in the lake is a short 12.5 years.

The salinity of Lake Turkana is higher than that of any other large African lake. This is due to the fact that the lake has no outlet, and that it has contracted in volume over the last 7,500 years. Very recent volcanic activity in the basin has also contributed to the high salinity of the lake (Beadle, 1981). The most common emergent plants are the grasses Paspalidium geminatum and Sporobolus spicatus, with extensive beds ofPotamogeton occurring in shallow bays (Hughes & Hughes 1992). The waters of Abaya and Chamo contain numerous submerged plants, such as Ceratophyllum demersum, Hydrocotyle sp., and Potamogeton spp., as well as floating plants like Lemna gibba, Nymphaea spp., and Ottelia ulvifolia (Hughes & Hughes, 1992).

Terrestrial Habitats

The evergreen bush and woodland of the Ethiopian Massif grade into deciduous bush in the Rift Valley. Extensive seasonal floodplains exist along the Omo River Delta, at the northern tip of Lake Turkana. Gallery forests of Acacia elatior, Balanites aegyptiaca, and Hyphaena coriacea grow along Lake Turkana's tributaries (Beadle, 1981; Hughes & Hughes, 1992). Swampy savanna forests of Acacia and Ficus species line the shores of Lake Abaya and species of Typha and Phragmites are common along the banks of both Lakes Abaya and Chamo.

19

Deliverable No. 1.3

Figure 15: Lake Turkana freshwater ecoregion

Fish

Lake Turkana is unique among the larger lakes of the eastern Rift Valley in that its aquatic fauna is dominated by Nilotic riverine species, rather than by species of the cichlid family. Compared to other large African lakes, Turkana has relatively low fish species richness, providing habitat for about 50 species, 11 of which are endemic. According to Hopson (1982), four fish communities live in the main lake: a littoral assemblage, an inshore assemblage, an offshore assemblage, and a pelagic assemblage.

Spawning migrations of fish are synchronized with the ecoregion’s seasonal flooding, which occurs from June through September. During this time, various fish species migrate up the Omo River (Hydrocynus forskalii, Alestes baremoze, Citharinus citharus,Distichodus niloticus, Barbus bynni) and other ephemeral affluents (Brycinus nurse, Labeo horie, Clarias gariepinus, Synodontis schall) to breed, for periods of both long and short duration (Beadle, 1981; Hopson, 1982; Lévêque, 1997).

Endemic fishes

The endemic species nearly all live in the offshore demersal or pelagic zone. Endemic chiclids include three halpochromine species adapted for deep water: Haplochromis macconneli, H. rudolfianus, and H. turkanae. Other species endemic to Lake Turkana include Barbus turkanae, Brycinus ferox, B. minutus, Labeo brunellii, Lates longispinis and Neobola stellae.

20

Deliverable No. 1.3

Other aquatic biota

Lake Turkana is an important site for waterbirds with up to 220,000 congregants having been recorded at one time and 84 waterbird species, including 34 Palearctic migrants, known from the lake (Bennun & Njoroge, 1999). Over 100,000 Calidris minutahave been recorded at the lake, in addition to smaller congregations of other non‐breeding waterbirds (Pelecanus rufescens, Phoenicopterus ruber, Vanellus spinosus, Charadrius hiaticula, C. asiaticus, C. pecuarius). Bird species present near Lake Abaya include Anhinga rufa, Bubulcus ibis, Casmerodius albus, Egretta garzetta, Haliaeetus vocifer, andScotopelia peli (Hughes & Hughes, 1992).

Other aquatic animals in the ecoregion include Hippopotamus amphibius, Crocodylus spp., and an endemic freshwater turtle, the recently discovered and imperiled Turkana mud turtle (Pelusios broadleyi) (Hughes & Hughes, 1992; Expert Center for Taxonomic Identification, 2000). Lakes Abaya and Chamo support notably large populations of Crocodylus niloticus and Hippopotamus amphibius (Hughes & Hughes, 1992). Three species of frog are endemic to the ecoregion (Bufo chappuisi, B. turkanae andPhrynobatrachus zavattarii).

Delineation

The Lake Turkana ecoregion is defined by the basins of lakes Turkana, Abaya and Chamo and the Omo River basin. Fish species in the ecoregion are mainly of Sudanian origin, providing evidence of a previous connection to the Sobat and the Nile Rivers (Beadle, 1981). For example, the Nilotic species, Nile tilapia (Oreochromis niloticus), Bagrus domac, and Nile perch (Lates niloticus) are abundant and common in lakes Turkana, Abaya, and Chamo (Hughes & Hughes, 1992). The Omo River basin also has several fish species in common with Lakes Turkana, Abaya, and Chamo. The Turkana basin was formed from tectonic movement during the early Miocene. Evidence suggests thatLake Turkana was once part of a larger body of water that included present day Lake Baringo (south) and the Lotikipi Plains (west). In addition, a connection with the Nile and its tributary, the Sobat River, may have existed more than once during particularly wet periods of the Pleistocene, with the most recent connection occurring not more than 7,000 years BP (Beadle 1981; Dgebuadze et al., 1994)

3.2.6 Horn of Africa (529)

Habitat Type

The temporary rivers, wadis, and sinkholes of the Horn ecoregion support a depauperated freshwater fauna adapted to fluctuating environmental conditions. The ecoregion corresponds to the xeric Horn of Africa, the most easterly portion of the continent covering the northern portion of Somalia and small portions of Ethiopia and Djibouti. The northern mountains drain primarily to the north toward the Gulf of Aden and to the southeast where several wadis cut through the plateau and flow to the Indian Ocean (Hughes & Hughes, 1992).

21

Deliverable No. 1.3

Rivers and other water bodies

From north to south, the major drainages flowing into the Indian Ocean from the interior plateau, include the ephemeral Jaceyl, Dhuudo, and Nugaal rivers. Among the many small, ephemeral drainages into the Gulf of Aden are the Durdur and Hodmo rivers.

Topography

A mountain chain runs parallel to the Gulf of Aden, reaching the highest point in Somalia on Shimbiris Mountain at 2,416 m. The land slopes down from this northern ridge to an interior plateau at about 600 to 1,000 m above sea level in the central portion of the ecoregion. The low‐lying coastal plain covers a narrow strip along the Gulf of Aden and the Indian Ocean.

The climate of the ecoregion is arid to semi‐arid with an annual rainfall of less than 250 mm. Rainfall can be particularly sparse at low elevations; for example, Berbera, on the Gulf of Aden, has a mean annual rainfall of 59 mm. Drought periods are common throughout the ecoregion. Rainfall is bimodal, with wet seasons from mid‐April to June and then again from October to December (FAO Inland Water Resources and Aquaculture Service Fishery Resources Division, 1999). The climate is hot and humid on the coast and hot and arid inland. In the north, temperatures can reach 42o C on the Gulf coast and can be as low as 0o C in the highlands (Hughes & Hughes, 1992).

Figure 16: Horn of Africa freshwater ecoregion

22

Deliverable No. 1.3

Freshwater habitats

Nearly all water bodies within this arid ecoregion are ephemeral. In the valley of the Nugaal River, there are several tugs (a temporary watercourse that spreads across flat land) and bullehs (endorheic depressions) (Hughes & Hughes, 1992). Along the tip of the Horn there are also pans, springs, and pools in many of the small northern wadis that discharge to the Gulf of Aden and the Indian Ocean. Sinkholes, salt pans, and subterranean water sources can be found inland.

Terrestrial Habitats

Most of the ecoregion is covered with barren desert or sparsely vegetated mixed scrub and grassland. The vegetation of the ecoregion is primarily deciduous shrub or bushland inland, with grassy scrublands on the coast. The most common tree species belong to the deciduous genera Acacia and Commiphora. The understory consists of shrubby herbs less than one meter high, such as Acalypha, Barleria, and Aerva. At lower elevations where rainfall is less consistent, vegetation becomes semi‐ desert scrubland. Around sinkholes in the interior limestone country and near tugs and bullehs, Acacia tortilis grows in association with Commiphora spp. (Hughes & Hughes, 1992). Thickets of dense vegetation often indicate surface or sub‐surface water. Evergreen and semi‐evergreen scrub grows in the mountains, and Afro‐montane vegetation including juniper forest grows at the highest elevations (Hughes & Hughes, 1992).

Fish Fauna

The aquatic fauna of this ecoregion is poorly known, however it is suspected that the ecoregion hosts a depauperate freshwater fauna able to live in an environment with highly variable water chemistry and flows. Eight species of freshwater fish are currently known to inhabit the Horn. Many of the fish species are adapted to life in challenging conditions. The lungfish (Protopterus amphibius) is capable of aerial breathing and aestivation (burrowing in the mud) for survival during anoxic or dry periods, respectively. Aphanius dispar is found in oasis pools with hypersaline to fresh water (FishBase, 2001). There are also several euryhaline fish. For example, the Jarbua terapon (Terapon jarbua) lives in river mouths, intertidal areas, and also travels up rivers, and Stenogobius gymnopomus and Syngnathus abaster are primarily estuarine species.

The monotypic Somalian blind barb (Barbopsis devecchii), the only ecoregional endemic, lives in caves of the ecoregion.

This ecoregion is defined by the xeric Horn of Africa and is characterized by a depauperate and poorly known aquatic fauna.

3.2.7 Lower Nile (523)

The lower Nile River provides a vital oasis for terrestrial and aquatic wildlife as it runs through the semi‐ arid Sahel and arid Saharan Desert of northern Sudan and Egypt. The boundaries of this ecoregion are defined by the lower Nile River from Khartoum, where the White and Blue Nile rivers converge, downstream to the Nile Delta. Notable features of the ecoregion include four major waterfalls over

23

Deliverable No. 1.3

which the Nile flows before emptying into the Aswan High Dam’s massive reservoir, named Lake Nubia in Sudan and Lake Nasser in Egypt.

Figure 17: Lower Nile freshwater ecoregion

Rivers and other water bodies

Primary water bodies in the ecoregion include the lower Nile River from Khartoum, where the White and Blue Nile rivers converge, downstream to the Nile Delta ; the areas draining to the lower Nile from the west; and areas draining from the east, including the Blue Nile and Atbara Rivers up to but excluding their uppermost reaches. Both the Blue Nile and the Atbara originate in the Ethiopian Highlands and carry large amounts of sediments, estimated annually at 1.4 billion metric tons (Waterbury, 2002).

Climate

The arid desert climate in the central portion of the ecoregion becomes increasingly hostile toward the north. Two seasons occur in the ecoregion. A hot, dry summer exists from April through October, and a cooler winter exists from November through March. Northern Sudan experiences a high mean daily temperature of 35oC in summer and 20oC in winter, and receives a mere 20 mm of annual rainfall (Hughes & Hughes, 1992). At Aswan in Egypt, temperatures range from a mean monthly minimum of 8oC and maximum of 23oC during the coolest month (January), to a minimum of 25oC and maximum of 41oC in the hottest month (August). Little to no precipitation falls in the Egyptian deserts. The western desert in Egypt experiences periods of years without rainfall, and precipitation in the hills of the eastern desert is highly variable. Streams can flow violently for several days after a storm drops up to 100 mm of precipitation, and then remain dry for several subsequent years (Hughes & Hughes, 1992).

In the late spring, rain clouds from the South Atlantic reach the Ethiopian highlands and drop their precipitation, providing the annual Nile flood that reaches Egypt between mid‐May and early July. Thereafter, the Nile surges with increasing volume for an average of 110 days, reaching its maximum height and volume in September. At the beginning of the flood in June, a parcel of water in the lower

24

Deliverable No. 1.3

Nile will take twelve days to flow the six hundred miles from the Aswan High Dam to Cairo, but the same journey requires only six days in full flood in September. The Blue Nile flood is so large that it effectively blocks the flow of the White Nile at Khartoum, contributing an average 59%, or 52 billion m³, to the Nile’s total flow. Further north, the discharge from the Atbara contributes another 13% or 11 bilm³ (Collins, 2002). Below the Atbara, the Nile flows through the harsh Nubian and Egyptian deserts for 2,415 kilometres without receiving any more water before discharging into the Mediterranean Sea.

A flat, featureless plain covers a majority of the ecoregion, though in the southeast the landscape rises sharply into the Ethiopian highlands through which flows the Great Abbay (Blue Nile) from Lake Tana. Fed by powerful tributaries, the Abbay runs through a deep canyon before entering onto the plains of the Sudan. The Blue Nile gorge has its own unique habitat with a narrow fringe of forest and scrub lining the river in its upper reaches (Rzóska, 1978). From Khartoum downstream, the Nile valley is a broad flat plain over 300 km wide at its narrowest point and almost devoid of vegetation throughout the desert of northern Sudan. However, drought‐tolerant plant species, such as Polygonum spp. and Potamogeton spp., occur in local stands and create narrow fringes along the mainstem Nile. Stands of Phragmites proliferate where the Nile flows into Lake Nubia (Dumont 1986; Hughes & Hughes, 1992).

At the northern edge of the ecoregion, west of the Nile mainstem, Lake Qârûn lies at the bottom of the Fayum depression, which is 71 km long and 20 km wide. Once fed by the Nile, Lake Qârûn now receives most of its flow as runoff from surrounding irrigated lands. As a result, its waters are becoming increasingly saline (Collins, 2002).

Fish Fauna

The lower Nile River provides vital habitat within a desert environment for an array of fish and other wildlife. Over 70 species of fish live in the ecoregion, many belonging to the families Alestiidae, Cichlidae, Citharinidae, Claroteidae, Cyprinidae, Mochokidae, and Mormyridae.

Other aquatic biota

In the northeastern corner of the ecoregion, Lake Qârûn supports large number of waterbirds; several grebes, as well as Aythya fuligula, Fulica atra, and Anas crecca, are abundant. Three species of turtle live within the lower Nile.

Of the nearly 50 indigenous taxa of molluscs within the entire Nile basin, 9 species are endemic. Within the Lower Nile ecoregion, 15 gastropods and 9 bivalves occur. Palearctic and Afrotropical species of gastropods overlap in the Saharan portion of the Nile basin, as well as in parts of the headwaters of the Blue Nile. For example, Brown (1994) (Brown 1994) observed Armiger cristaliving together with Ceratophallus natalensis and Segmentorbis angustus in a pool alongside a tributary to the Blue Nile River.

25

Deliverable No. 1.3

Delineation

The headwaters of the Blue Nile and Atbara Rivers are also separated into the Ethiopian Highlands ecoregion due to their swift‐flowing, steep nature and different aquatic fauna. The valley of the Nile River was inundated by the Tethys Sea up through the Cretaceous period (approximately 65 million years ago) (Dumont 1986). Five geologic phases of the Egyptian Nile can be distinguished, each separated by a dry period of no flow: the Eonile, Palaeonile, Protonile, Prenile, and the present Neonile (Rzóska, 1978; Dumont, 1986). The present Nile valley developed at the end of the Miocene. The rise of the high volcanic plateaus in Ethiopia, probably during the Oligocene, is responsible for the origin and direction of the Blue Nile and the Atbara River (Rzóska 1978). Tectonic movement and climatic changes have changed the Nile’s course and flow many times. The Nile Basin has few endemic fish, due to the frequent cessation of flow that inhibited the evolution and persistence of aquatic species (Beadle, 1981; Dumont, 1986).

3.2.8 Shebelle – Juba (531)

The xeric systems of this ecoregion include the Wabi Shebelle and Juba basins with the ecoregion extending from Kenya to Somalia along the coast of the Indian Ocean and inland to the Ethiopian Highlands. During flooding, the rivers often spill over their banks and inundate adjacent floodplains.

All of the lower Wabi Shebelle and adjacent areas are very dry. The most reliable month for rain is April, followed by May, whereas no rain falls between October and September. The hottest months are February and March.

Freshwater habitats

Draining from the southeastern escarpment of the eastern Ethiopian highlands, the Wabi Shebelle and the Fafan Rivers flow through the Somalian desert, although they do not reach the Indian Ocean. The Wabi Shebelle is the major river of the central Somali region. Rising between the Arsi and Bale Mountains, it flows in a southeasterly direction to Somalia. In its lower section, the Wabi Shebelle and its main seasonal tributary from the east, the Fafan, cut through a series of wide, flat shelves of sedimentary rocks made of sandstone, limestone, and gypsum. Wabi Shebelle, with a catchment area of 205,407 km2, winds a length of 1340 km inside Ethiopia, and a further 660 km in Somalia (Ethiopian Mapping Authority 1988). The Wabi Gestro, the Ghenale River, and the Dawa Parma River drain the southwestern escarpment of the eastern Ethiopian highlands. These rivers unite and become the Juba River, which eventually drains into the Indian Ocean (Westphal, 1975). These Juba tributaries arise just east of Abaya and Chamo Lakes, but are separated from the lake drainages by a high mountainous divide. According to Roberts (1975), midway between the lower courses of the Wabi Shebelle and the Juba there is a low‐lying limestone plateau with extensive underground waterways radiating out from it.

26

Deliverable No. 1.3

Terrestrial Habitats

Floodplains are often covered in a tangled growth of small bushes and herbs, which include wild relatives of cotton. Large trees are not naturally found on the floodplains, but heat‐tolerant species, including Hyphaene thebaica, have been planted in settlements.

Figure 18: Shebelle‐ Juba freshwater ecoregion

Fish Fauna

The rivers in this ecoregion are believed to host many Nilo‐Sudanic fishes similar to the southern rift valley lakes (Lakes Chamo and Abaya). It is believed that these lakes and the Shebelle‐Ghenale River basins had former connections with the upper White Nile as recently as 7,500 years ago (Roberts 1975; McClanahan & Young 1996). Some of the rivers in this ecoregion (e.g., Ghenale River) support abundant populations of fish.

Endemic fish, including Bagrus urostigma, Labeo boulengeri, Labeo bottegi, and Synodontis geledensis, live in the rivers of this ecoregion. Most of the Nilotic species found in Lake Abaya, with the exception of Hyperopisus bebe, are also present in the Wabi Shebelle‐Juba drainage (Roberts, 1975). Another important feature of the area is the presence of subterranean waterways, which are inhabited by the endemic monotypic fish genera Uegitglanis and Phreatichthys. Both the clariid catfish (U. zammaranoi) and the cyprinid (P. andruzzii)lack visible eyes and are depigmented and scaleless.

The vegetation alongside the middle section of the Ghenale River also supports populations of the vulnerable Prince Ruspoli’s turaco (Tauraco ruspolii), white‐winged collared‐dove (Streptopelia reichenowi), and Jubaland weaver (Ploceus dicrocephalus). Along the coast in Somalia are several areas of importance for waterbirds, for example the Jasiira lagoon is known to support congregations of Phoenicopterus ruber and Egretta gularis.

A continuous escarpment, running in a wide curve from the Kenyan border to northern Somalia, forms the western and northern borders of this ecoregion, while the southwestern part of this escarpment

27

Deliverable No. 1.3

forms the eastern wall of the Rift Valley. The escarpment rises northwards and attains its maximum elevation of over 3,000m near the Chilalo Massif in Ethi opia. Several endemic fishes live in the streams and subterranean waters of this xeric ecoregion.

Delineation

A continuous escarpment, running in a wide curve from the Kenyan border to northern Somalia, forms the western and northern borders of this ecoregion, while the southwestern part of this escarpment forms the eastern wall of the Rift Valley. The escarpment rises northwards and attains its maximum elevation of over 3,000m near the Chilalo Massif in Ethiopia. Several endemic fishes live in the streams and subterranean waters of this xeric ecoregion

The native freshwater flora and fauna of this vast ecoregion has been poorly investigated. Although the riparian vegetation has been described to some extent, little is known about the upland vegetation. Without better information, identification of conservation priorities is difficult.

28

Deliverable No. 1.3

4 Terrestrial ecoregions

There are several alternative formal naming schemes for the Earth's terrestrial ecoregions; e.g. Usdvardy (1975), Encyclopaedia of Earth Ecoregions, Wikipedia Ecoregions, TNC Ecoregion, Global 200 Ecoregions and others.

One of the most widely used, developed by the World Wildlife Foundation, recognizes 867 separate ecoregions. The ecoregions are categorized within 14 biomes and eight biogeographic realms to facilitate representation analyses.

The Encyclopaedia of Earth defines the ecoregion approach as following: “An ecoregion is a contiguous area characterized by well‐defined similarity in flora and fauna as well as geomorphology, climate and soils. Ecoregions are generally relatively large geographic units on the order of 50,000 square kilometres or more. Ecoregions may be terrestrial or marine, and do not recognize any political boundaries or landscape alterations by humans. Generally an ecoregion is depicted by a geographic descriptor coupled with a biome identity, further articulating one or more specific climatic or dominant plant community appellations”.

Figure 19: Ecoregions of the world: 14 biome (colour) and 8 biographic realms to facilitate representation analyses (Source: WWF) With this classification (http://www.globalspecies.org/ecoregions/display/AT0112), Ecoregions of Ethiopia are classified as follows:

29

Deliverable No. 1.3

Ethiopian montane forests

The Ethiopian Montane Woodland ecoregion is biodiverse, poorly known and highly threatened. The rugged topography of this ecoregion rings the highlands of Ethiopia and Eritrea, extending to outlying massifs in Sudan. Formed by volcanic forces 75 million years ago, these highlands were covered with Eurasian tundra‐like vegetation during the last Ice Ages. Today, remnant patches of natural vegetation consist mostly of podocarps and juniper forests, with some acacias found at lower elevations. While soils are rather infertile, this area is densely populated and most land has been converted to agriculture. Notable endemics found here include the yellow‐throated serin and Prince Ruspoli's turaco. Many of the endemic species are threatened due to the loss of their habitat.

This ecoregion is highly biodiverse, relatively poorly known and highly threatened. It is mainly found on the margins of the highlands of Ethiopia and Eritrea. The altitudinal limits of the ecoregion vary from one locality to another depending upon annual precipitation, but are generally between 1,100 and 1,800 meters (m). From May to October, winds blow from the southwest and bring rainfall to the Ethiopian portion of the ecoregion. During the rest of the year, onshore winds from the Red Sea bring moisture to the Eritrean side of the mountains. Rainfall varies from 600 millimetres (mm) in the driest sites to more than 1,500 mm in wetter areas. Humidity is sometimes higher than would be expected from these figures, due to cloud precipitation and local interactions between topography and weather. Unlike the moist equatorial mountains, the effects of cold descend further down on these dry highlands. Temperatures vary according to the season and elevation, but mean maxima lie between 18°C and 24°C. Mean minima are between 12°C and 15°C.

Ancient Precambrian basement rocks form the substrate of the montane forests in southwestern Ethiopia and Eritrea. The topography is generally rugged, and soils are rather infertile. The main Ethiopian and Eritrean dome began to rise 75 million years ago, eventually dividing into two halves, the northern and southern highlands. A turbulent volcanic period ended four to five million years ago, followed by climatic fluctuations in the Pliocene and Pleistocene. Glaciers formed on the peaks of the Ethiopian highlands while surrounding areas, including this ecoregion, were covered with vegetation similar to Eurasian tundra. Separated by the Great Rift Valley, the northern and southern highlands were colonized by new species from different directions. The jebels and escarpments along the Red Sea linked Eritrea and northern Ethiopia with the Palearctic region while southern Ethiopia had a rift‐ wall connection to the Horn of Africa. Both the western and eastern highlands were invaded by tropical species that could penetrate the Nile floodplains in the west or the Kenyan deserts in the south. Despite the climatic differences, the surrounding lowlands provided the most consistent source of new species, so that these highlands show both Afrotropical and Palearctic influences.

30

Deliverable No. 1.3

Figure 20: Ethiopian montane forest ecoregion This ecoregion is based on the ‘East African evergreen and semi‐evergreen bushland and thicket’ and ‘cultivation and secondary grassland replacing upland and montane forest’ vegetation units. The cultivation and secondary grassland areas are included in an effort to cover potential vegetation. The ecoregion lies between 1,100 meters (m) and 1,800 m in elevation.

Ethiopian montane grasslands and woodlands

During the last Ice Age, this entire ecoregion would have been similar to the Eurasian tundras, while still higher elevations were capped with glaciers. As the climate warmed, these highlands were recolonized, resulting in a biota with a combination of Palearctic and Afrotropical influences. Ranging up to 3,000 m, the montane vegetation includes Hagenia, Podocarpus and Juniperus, but intact vegetation is increasingly fragmented. The region is densely populated because it contains the best arable land in Ethiopia. A variety of Ethiopian endemics can be found, including the critically endangered Walia ibex (Capra walie) and endangered mountain nyala (Tragelaphus buxtoni). Plant endemism in this region peaks in the forest/ woodland/ grassland complex.

This is a biologically rich and severely threatened ecoregion (94,700 square miles) that covers the majority of two Ethiopian mountain massifs (Eastern and Western), separated by a part of the African Great Rift Valley. This ecoregion ranges from 1,800 m to 3,000 m in elevation, with montane forest at lower altitudes and Afroalpine habitat higher up. The climate of these highlands is greatly affected by their topography, and also by the movement of the Inter Tropical Convergence Zone (ITCZ). As the ITCZ moves north between May and October, warm moist air is drawn from the Indian Ocean so that rain falls on the southern slope of the Ethiopian Highlands. During the remainder of the year, the ITCZ lies south of the highlands and the winds are from the Red Sea to the north and east. These winds typically contain less moisture, which mainly falls on the northern side of the highland massif. Overall, the highest annual rainfall (up to 2,500 mm) is on the southwestern scarp faces of the highlands, which support montane or transitional forests, while over most of the ecoregion the rainfall is around 1,600 mm annually. 31

Deliverable No. 1.3

Figure 21: Ethiopian montane grasslands and woodlands Geologically the area consists of a Precambrian basement capped in most places by thick Tertiary basaltic lava flows (the Trap Series). The ancient Precambrian rocks form the substrate of the montane forests in southwestern Ethiopia and Eritrea. Mesozoic rocks form the surface outcrops of the southeastern highlands of Ethiopia, while Tertiary basalts form the surface rocks of the remainder of the Ethiopian and Eritrean massifs. The latter attain a thickness of 3,000 to 3,500 m in the Simien Mountains. Forest soils in Ethiopia are mainly ferrosols derived from these volcanic substrates.

White (1983) nests this ecoregion within a larger ‘undifferentiated montane vegetation’ unit. The ecoregion roughly follows the 1,800 m contour for the lower elevation and 3,000 m contour for the upper elevation. Although the South and Central Highlands are recognized as two areas of bird endemism (Stattersfield et al., 1998), they contain floral and faunal similarities (WWF, 1998).

Ethiopian montane moorlands

While the Ethiopian Montane Moorlands ecoregion makes up only 2% of the total land area in Ethiopia (9,700 square miles), it contains 80% of land above 3000 m in the Afrotropical realm. Split into northern and southern massifs, these highlands were formed by turbulent volcanic forces that ceased only 4 to 5 million years ago. At the end of the last Ice Age, montane species were restricted to higher altitudes by the warming climate. High levels of endemism are found here and the region’s biota demonstrates evolutionary links to both the Palaearctic and the Afrotropical realms. The vegetation, known as wurch to Ethiopians, consists of grassland and moorland with abundant herbs. Most plant species (many of which are endemic) show adaptations to the extreme conditions found at high altitudes. Stretching out across Ethiopia, these pockets of high altitude vegetation harbor the last populations of the critically endangered Ethiopian wolf (Canis simensis) and several small mammal endemics.

Ecoregion Delineation

This ecoregion forms part of the Afroalpine center of plant diversity across East and Northeast Africa (WWF and IUCN 1994). The lower boundaries are derived from White’s ‘altimontane’ vegetation unit, roughly following the 3,000 m contour. The Ethiopian Montane Moorlands are poorly developed compared to other East African moorland areas, lacking typical Afroalpine species like Dendrosenecio.

32

Deliverable No. 1.3

However, they possess considerable endemism and contain affinities to the Palearctic realm, such as species of Rosa and Primula (Hedberg & Hedberg, 1979, Vuilleumier &Monasterio, 1986).

Figure 22: Ethiopian montane moorlands ecoregion

33

Deliverable No. 1.3

Ethiopian xeric grasslands and shrublands

The Ethiopian xeric grasslands and shrublands is an arid, semi‐desert ecoregion bordering the Red Sea and the Gulf of Oman. This ecoregion lies mainly between sea level and 800 meters (m) elevation. There are, however, many hills and massifs, which range up to 1300 m as well as outstanding fault‐ induced depressions, such as the Danakil, lying as low as 155 m below sea level. This region is extremely active tectonically, experiencing many earthquakes and intermittently active volcanoes. Rainfall is very low and yearly averages range from 100 to 200 (mm), with less rain falling closer to the coast. There are many species of interest, including the endemic Archer's lark (Heteromirafra archeri), a species of dragon tree (Dracaena ombet), and a large suite of desert ungulates, including the last viable population of African wild ass (Equus africanus somalicus).

Figure 23: Ethiopian xeric grasslands and shrublands ecoregion This ecoregion extends inland from the Red Sea and the Gulf of Oman, including the Dahlak Archipelago and other islands, stretching from the Sudanese‐Eritrean border, south through Ethiopia to Djibouti and eastwards into Somalia, in the Somaliland region of the country. While it mainly lies between sea level and 800 m, there are many arid hills and massifs up to 1300 m. Higher massifs such as the Goda and Mabla in Djibouti are considered to be outliers of the Ethiopian Montane Forest ecoregion. There are also fault‐induced depressions, such as the Danakil Depression and Lac Assal, lying as much as 160 m below sea level. Elevation generally increases westward towards the Ethiopian and Eritrean highlands. The region is extremely active tectonically, and it experiences many earthquakes associated with the continuing enlargement of the Rift Valley. Volcanoes in the ecoregion are also intermittently active. Basement rocks are composed mainly of Tertiary lava flows, although there are also Quaternary basinal deposits at the northern end and pre‐Cretaceous basinal deposits on the northern coast of Somalia. Soils developed over the lava deposits are mainly lithosols, while regosols are predominant on the Quaternary and pre‐Cretaceous basinal deposits. There are very few permanent watercourses. The most notable is the Awash River of Ethiopia that terminates in a series of lakes near the border with Djibouti. 34

Deliverable No. 1.3

The climate is very hot and dry. Mean annual rainfall varies from less than 100 mm close to the coast to around 200 mm further inland. Mean minimum temperatures range from 21° to 24°C, and mean maximum temperature is around 30°C. Phytogeographically, White (1983) regarded this ecoregion as part of the Somali‐Masai regional center of endemism and mapped the vegetation as ‘Somalia‐Masai semi‐desert grassland and shrubland’. Along the coast, mangroves occur in muddy areas, primarily around wadi "outwashes" and inlets, while further inland, vegetation changes to grass shrub steppe. Acacia melliferaand Rhigozum somalense dominate the basaltic lava fields while scattered Acacia tortilis, A. nubica, andBalanites aegyptiaca can be found in the sandy plains. Stands of Hyphaene thebaica occur in depressions and along wadis.

The boundaries of this ecoregion follow the ‘Somalia‐Masai semi‐desert grassland and shrubland’ vegetation unit of White (1983), from just north of the Sudan/Eritrea border to the extremely narrow coastal strip along the northern coast of Somalia (Somaliland). This eastern border follows the range limit of some species like the Dorcas gazelle (Gazella dorcas), and encompasses the range of others, such as the African wild ass (Equus africanus). White’s (1983) larger ‘Somalia‐Masai semi‐desert grassland and shrubland’ unit that extends further east along the Horn of Africa was separated into distinct ecoregions based on their unique plant and vertebrate compositions.

East Sudanian savanna

The East Sudanian Savanna is a hot, dry, wooded savanna composed mainly of Combretum and Terminalia shrub and tree species and tall elephant grass (Pennisetum purpureum). The habitat has been adversely affected by agricultural activities, fire, clearance for wood and charcoal, but large blocks of relatively intact habitat remain even outside protected areas.

Figure 24: East Sudanian savanna ecoregion This ecoregion lies south of the Sahel in central and eastern Africa, and is divided into a western block and an eastern block by the Sudd swamps in the Saharan Flooded Grasslands ecoregion. The western block stretches from the Nigeria/Cameroon border through Chad and the Central African Republic to

35

Deliverable No. 1.3

western Sudan. The eastern block is found in eastern Sudan, Eritrea, and the low‐lying parts of western Ethiopia, and also extends south through southern Sudan, into northwestern Uganda, and marginally into the Democratic Republic of Congo around Lake Albert.

Topographically, the ecoregion is flat, mainly lying between 200 m and 1,000 m in altitude, although elevation rises slightly in western Ethiopia and around Lake Albert. The climate is tropical and strongly seasonal. Mean monthly maximum temperatures range from 30° to 33°C and mean minimum temperatures are between 18°C and 21°C. The annual rainfall is as high as 1,000 mm in the south, but declines to the north with only 600 mm found on the border with the Sahelian Acacia Savanna. Rainfall is highly seasonal, and during the rainy season from April to October, large areas of southern Chad and northern parts of the Central African Republic become totally inundated and inaccessible. During the dry season most of the trees lose their leaves and the grasses dry up and may burn.

Geologically, the ecoregion overlies a mixture of Precambrian basement rocks, and a number of post‐ Jurassic sedimentary basins. The soils are mainly ultisols and alfisols in the south with entisols in the north. Some oxisols and vertisols are also found in the east. The ecoregion is sparsely populated, with typical population densities ranging between 1 to 5 people/km2, although there may be as many as 20 to 30 people/km2 in some places.

White (1983) classified this region phyto‐geographically within the Sudanian regional centre of endemism, as it supports more than 1,000 endemic species of plants. The vegetation is mapped as undifferentiated woodland that comprises trees, which are mainly deciduous in the dry season, with an understory of grasses, shrubs and herbs. Typical trees in the western block of the ecoregion include Anogeissus leiocarpus, Kigelia aethiopica, Acacia seyal and species of Combretum and Terminalia. In the eastern block woody vegetation is dominated by Combretum and Terminalia species, as well as Anogeissus leiocarpus, Boswellia papyrifera, Lannea schimperi and Stereospermum kunthianum.

This ecoregion, along with the West Sudanian Savanna, forms part of the Sudanian regional center of endemism, and contains two vegetation units, the ‘Sudanian undifferentiated woodland’ and ‘Sudanian woodland with abundant Isoberlina’ (White 1983). Although these two units differ in the presence of Isoberlina, with the northern unit being slightly drier, they share similar animal assemblages. The West and East Sudanian Savannas are also similar in terms of their broader species assemblages, but they were split into two separate ecoregions near the Mandara Plateau because a number of plant taxa do not cross this boundary (WWF, 1998). Several modifications to White’s boundaries have been made, including an extension of the Sahelian Acacia Savanna below Lake Chad, and a northern boundary considerably further south than White’s boundary (WWF, 1998). Edaphic grassland and communities of Acacia and broadleaved trees identified by White have also been largely excluded. The eastern portion of this ecoregion forms an extension of undifferentiated woodland, following White’s ‘Ethiopian undifferentiated woodland’ and ‘Ethiopian transition from undifferentiated woodland to Acacia deciduous bushland and wooded grassland.’ This area was extended to include ‘Sudanian undifferentiated woodland’ south towards Lake Albert and Mount Elgon. Udvardy (1975) delineates a biogeographic boundary between the Western and Eastern Sahel, which would effectively split the western section of this ecoregion in half.

36

Deliverable No. 1.3

Victoria basin forest‐savanna mosaic

The rolling hills and plateaus of the Victorian Basin Forest‐Savanna Mosaic ecoregion are a unique landscape where species from West African forest ecosystems converge with those from east African forest‐savanna mosaics. The region’s scattered lakes, rivers, and marshes add to the great diversity of habitats supporting a wide variety of species.

Figure 25: ictoria basin forest‐savanna mosaic (http://www.globalspecies.org/ecoregions/display/AT0721)

Sahelian Acacia savanna

Spanning the entire African continent, the Sahelian Acacia Savanna stretches in a continuous band from the Atlantic Ocean to the Red Sea. Although not particularly rich biologically, these savannas once supported a large and diverse ungulate community. The first European explorers to visit the region found vast herds of game, even larger in number than those of eastern and southern Africa. Sadly, these herds have been reduced to mere remnants due to nearly a century of unregulated over‐hunting with modern firearms and vehicles, coupled with habitat loss. This ecoregion includes some of the world’s poorest countries, which have scarce resources for conservation. Existing conservation efforts are therefore inadequate and the biological values of the ecoregion remain highly threatened.

37

Deliverable No. 1.3

Figure 26: Sahelian Acacia savanna ecoregion The Sahelian Acacia Savanna stretches across Africa from northern Senegal and Mauritania on the Atlantic coast to Sudan on the Red Sea, varying in width from several hundred to over a thousand kilometres. The word "sahel" means "shore" in Arabic and refers to the transition zone between the wooded savannas of the south and the true Sahara Desert. The ecoregion thus lies south of the Southern Saharan Steppe and Woodland Ecoregion and north of the West and East Sudanian Savanna Ecoregions.

The topography is mainly flat and the majority of the ecoregion lies between 200 m to 400 m in elevation. The few isolated mountain massifs rising from this plateau, some over 3,000 m high, have been assigned to other ecoregions due to their distinctive fauna and flora. The climate is tropical, hot, and strongly seasonal. The monthly mean maximum temperatures vary from 33° to 36°C and monthly mean minimum temperatures are between 18° to 21°C. The annual rainfall is around 600 mm in the south of the ecoregion, but declines rapidly to the north to around 200 mm. Most rain falls in the summer months of May to September, followed by a 6 to 8 month dry season, during which time the woody vegetation loses its leaves and the grasses dry up and may burn. The movements of the Intertropical Convergence Zone (ITCZ) determine the quantity of rainfall in a particular year ‐ if it penetrates far to the north there will be a long rainy season and good rains; if it does not move sufficiently far north, then the rains may fail totally. During the winter, hot dry winds (known in much of West Africa as the "Harmattan") blow from the north, often bringing dust and sand from the Sahara with them.

Geologically, the ecoregion mainly overlies a number of post‐Jurassic sedimentary basins, but the higher land found between the Central African Republic and Sudan is made up of Precambrian basement materials. There are also recent deposits from huge lakes, which were present during the pluvial periods of a few thousand years ago, cantered on present day Lake Chad and the Inner Niger Delta. These lakes have been drying for thousands of years and today cover only fractions of their former extent, although the region might have been even dryer between 12,000 and 20,000 years BP. Other smaller lakes would have been present in the past. The soils of the ecoregion are mainly entisols, with some aridisols found towards the north and alfisols on the highest land. Throughout much of the region the soils are highly permeable and permanent surface water points or watercourses are rare.

38

Deliverable No. 1.3

The Sahelian Acacia Savanna ecoregion follows two of White’s vegetation units: the ‘Sahel Acacia wooded grassland and deciduous bushland’ and the ‘Northern Sahel semi‐desert grassland and shrubland’ (White, 1983). Two small modifications to White’s linework include moving the Adrar de Iforas from this ecoregion to the West Saharan Montane Xeric Woodland, and extending the eastern boundary of the ecoregion to the Ethiopian Highlands (WWF, 1998). Udvardy (1975) splits this region into the Western and Eastern Sahel biogeographical provinces.

Somali Acacia‐Commiphora bushlands and thickets

In the heart of these wide‐sweeping grasslands and associated Acacia‐Commiphora woodlands, the world’s most spectacular migration of large mammals occurs each year. Wildebeests, plains zebras, and Thomson’s gazelles traverse the Greater Serengeti Ecosystem, triggered by cyclical wet and dry seasons. Parts of the world famous Serengeti National Park and the Ngorongoro Conservation Area are located in this ecoregion; both have been designated as World Heritage Sites and Biosphere Reserves. Of the three Acacia‐Commiphora Bushland and Thicket ecoregions, this southern unit receives the most rain and is closely associated with the Serengeti Volcanic Grasslands. The main threats to the ecoregion are the same as other savanna areas in the region, poaching of large mammals for body parts and meat, and expansion of pastoralism and agricultural use of the area with associated loss of tree cover.

Figure 27: Somali Acacia‐Commiphora bushlands and thickets ecoregion (http://www.worldwildlife.org/ecoregions/at0716) The ecoregion is located in northern and central Tanzania, extending into southwestern Kenya, around the eastern margins of Lake Victoria. The ecoregion forms the southern border of White’s (1983) phytogeographical classification for the Somali‐Masai Acacia‐Commiphora deciduous bushland and thicket. The predominant plants include species of Acacia, Commiphora, and Crotalaria and the grasses

39

Deliverable No. 1.3

Themeda triandra, Setaria incrassata, Panicum coloratum, Aristida adscencionis, Andropogon spp., and Eragrostis spp. (White, 1983). Within Tanzania, the ecoregion is bisected by two patches of Serengeti Volcanic Grassland and patches of East African Montane Forest. The volcanic grasslands are an integral habitat of the greater Serengeti ecosystem. However, the grasslands are considered a separate ecoregion due to their unique grassland communities, found only on the fine volcanic soil, or "vertisol."

The habitat transitions to miombo woodland towards the south, more Acacia‐Commiphora Bushland and Thicket towards the north, and Zanzibar‐Inhambane Coastal Forest‐Savanna Mosaic towards the east. The western portion of the ecoregion is included in the greater Serengeti ecosystem. Topographically, the ecoregion is situated on the Central African Plateau and slopes upward from east to west. Elevation ranges from 900 m in the Speke Gulf up to 1,850 m in the Gol Mountains. The majority of the ecoregion falls between 900 and 1,200 m.

The climate of the region is tropical with seasonal rain that falls in a bimodal pattern. The long rains occur from March to May and the short rains from November to December. Mean rainfall is 600 to 800 mm annually through most of the region. Extremes include 500 mm in the dry southeastern plains and 1,200 mm in the northwestern region located in Kenya. Rainfall is variable such that the short rains may fail in a given year or rain may occur between the two rainy seasons, thereby joining the two. Temperatures are moderate with mean maximum temperatures as high as 30°C at lower elevations and as low as 24°C at the highest parts of the ecoregion. Mean minimum temperatures are between 9° and 18°C, and normally between 13° to 16°C.

During the long dry season (August to October), the grasslands can become extremely parched, and many of the trees and bushes lose their leaves. Fires occur naturally in the ecosystem. Both fire and elephant browsing play an important role in converting dense thicket and bushland into grassland. However, a large number of fires are started by pastoralists to promote new vegetative growth for their livestock.

Geologically, the entire area is underlain by Precambrian basement rocks (up to 2.5 billion years old) that have been deformed, then eroded over hundreds of millions of years. Ultisols and alfisols lay over basement rocks, with patches of vertisols close to Lake Victoria. The hills in the ecoregion are formed of more recent sedimentary rocks, and some are recent volcanics with some active volcanoes. In many areas late Precambrian outcrops of granitic gneisses and quarzite project from the surface as inselbergs (locally called kopjes).

This ecoregion forms the southern part of the ‘Somali‐Masai Acacia‐Commiphora bushland and thicket’ vegetation unit of White (1983). It contains higher levels of rainfall than the areas further north, and floristic and faunistic patterns that are distinct. It is divided from the Northern Acacia‐Commiphora Bushland and Thickets ecoregion roughly by the chain of mountains along the Kenya‐Tanzania border. This represents the extent of some species like the gerenuk (Litocranius walleri), which is present in the north, but is absent in much of the south. The southern boundary of this ecoregion directly follows White (1983).

40

Deliverable No. 1.3

Northern Acacia‐Commiphora bushlands and thickets

The ecoregion, comprised of semi‐arid mixed woodland, scrub and grassland, is reasonably protected within a well‐functioning system of national parks and other reserves. However, numbers of humans and livestock are increasing outside protected areas, and nomadic pastoralism is declining in favor of settlement, causing environmental degradation through heavy grazing and agricultural expansion. Water is always in short supply in this region, where one or both rainy seasons commonly fail. Certain species such as Grevy’s zebra (Equus grevyi) have undergone severe declines because of competition with livestock for, and often exclusion from, water supplies. Poaching also threatens some of the large herbivores found here, particularly the black rhinoceros (Diceros bicornis) and, until recently, the African elephant (Loxodonta africana).

Figure 28: Northern Acacia‐Commiphora bushlands and thickets ecoregion This ecoregion extends from the southeast corner of Sudan and northeast Uganda, through much of lowland Kenya, reaching as far as the border with the Northern Zanzibar‐Inhambane Coastal Forest Mosaic. To the north, it is replaced by drier savanna and semi‐desert vegetation. To the south it grades into the southern Acacia‐Commiphora bushland and thicket around the Kenya‐Tanzania border.

Climatically, the area falls within the seasonal tropics, with seasonality controlled by movement of the Inter Tropical Convergence Zone. Mean maximum temperatures are 30°C in the lowlands, falling to around 24°C in the higher areas. Mean minimum temperatures range from 18 to 21°C. Annual rainfall ranges from 200 millimetres (mm) in the drier areas near Lake Turkana, to about 600 mm closer to the Kenyan Coast. It is strongly seasonal, with most precipitation occurring in the long rains, typically from March to June, and less falling in the short rains of October to December. The timing and amounts of rainfall vary greatly from year to year, and it is fairly common that one, or both, rainy seasons fail. In Turkana, Kenya, and southern Sudan, there is typically one rainy period per year. During drier times the desiccated vegetation becomes highly flammable and large areas of the ecoregion burn every year.

Geologically, the ecoregion is situated on a mixture of basement rocks. These range from Precambrian basement, through Tertiary volcanic lavas, to Quaternary basin and dune formations. These sediments outcrop at the surface in many places due to the shallow soils. Apart from these outcrops, the 41

Deliverable No. 1.3

ecoregion is generally level and gently undulating, with lowest elevation in the east, north and northwest (elevations of 200 meters (m) to 400 m), increasing towards the south and southwest, where elevations rise up to 1,000 m, but there are a number of notable mountains, such as Moroto in Uganda, which exceeds 3000 m, and several in Turkana which are above 2000 m. The soils of the southeast portion of the ecoregion are mainly aridisols, with entisols around Lake Turkana Basin. Along the western margins of the ecoregion, vertisols can also be found.

The ecoregion is part of White’s Somali‐Masai regional center of phytogeographical endemism and is predominately Acacia‐Commiphora bushland and thicket. Common plant genera include Acacia, Commiphora, and Boswellia, and Aristida, Stipa, and Chloris grasses.

This ecoregion forms the central portion of the ‘Somali‐Masai ''Acacia‐Commiphora'' bushland and thicket’ vegetation unit of White. This larger unit was separated into three ecoregions based on different bioclimatic and associated floral and faunal patterns. The ‘East African evergreen bushland and secondary Acacia wooded grassland’ of White was included to better reflect potential vegetation. The ecoregion is bound by the alluvial plains and rocky plateau of the Masai Xeric Grassland and Shrubland ecoregion and the Tana River to the northeast, which represent the extent of some species, such as the common eland (Taurotragus oryx), Bohor reedbuck (Redunca redunca) and Burchell’s zebra (Equus burchelli). To the south it is divided from the Southern ''Acacia‐Commiphora'' Bushland and Thicket ecoregion roughly by the chain of mountains along the Kenya‐Tanzania border. This represents the extent of some species like the gerenuk (Litocranius walleri), which is present in the north, but is absent in much of the south. Additional studies of herbs, birds and plants may help to better define this ecoregion.

Masai xeric grasslands and shrublands

This ecoregion lies in northern Kenya, and includes a mix of desert, savanna woodland, wetland, and bushland. It is known for its cultural history and fossil species, including the early hominids Homo habilis and Homo erectus, as well as a giant tortoise and giant crocodile. Present day species found in this ecoregion include three endemic species of amphibians and one endemic turtle associated with Lake Turkana. In the drier areas several large mammal species occur such as cheetah, lion, elephant, beisa oryx, Grevy’s zebra and reticulated giraffe. Drought and pastoralism have had a substantial impact on the habitats of the area, some of which have been reduced to a desert‐like state, and the populations of many of the large mammals have been greatly reduced. Black rhinoceros (Diceros bicornis) has been extirpated from the ecoregion.

42

Deliverable No. 1.3

Figure 29: Masai xeric grasslands and shrublands ecoregion This ecoregion is located in the northern part of Kenya and extreme southwestern Ethiopia. It encompasses most of Lake Turkana and the Omo River Delta, and grades into the savanna woodlands of the Northern Acacia‐Commiphora Bushland and Thicket ecoregion to the west and the Somali Acacia‐Commiphora Bushland and Thicket to the east. Mostly lying between 200 and 700 m elevation and gently undulating, it includes the Chalbi Desert, a large flat depression between 435 m and 500 m formed from the bed of an ancient lake.

The climate is hot and dry over most of the year, with mean maximum temperatures of around 30° C and mean minimum temperatures between 18° C and 21° C. There is a short wet season between March and June as the Intercontinental Convergence Zone moves north. Mean annual rainfall is between 200 and 400 mm. Geologically, the ecoregion is located on an outlier of the Tertiary volcanic materials that make up the Ethiopian massif. The soils of the area are complex, and vary from bare rocks and lithosols, with solonchaks, yermosols, and regosols indicating the general desiccation of the area.

This ecoregion forms the southern outlier of White’s ‘Somalia‐Masai semi‐desert grassland and shrubland,’ including the area around Lake Turkana and the Chalbi Desert. Although, it contains a similar vegetation structure to the Ethiopian Xeric Grassland and Shrubland ecoregion further north, it was elevated to ecoregion status due to its disjunct position, arid nature, and elements of savanna woodland communities.

43

Deliverable No. 1.3

5 Other Ethiopian regional typologies

Ecosystems of Ethiopia

Ethiopia is endowed with diverse ecosystems in which diverse flora and fauna as well as microbial resources are found. The major ecosystems include: Afroalpine and subafroalpine, montane dry forest and scrub, montane moist forest, Acacia‐Comiphora woodland, Combretum‐Terminalia woodland, Lowland humid forest, Aquatic, wetland, Montane grassland, and Desert and semidesert ecosystems (http://et.chm‐cbd.net/biodiversity/ecosystems‐ethiopia).

Afroalpine and Subafroalpine Ecosystem

The areas which on the average higher than 3200 meters above sea level (m.a.s.l) are generally referred to as the Afroalpine and Subafroalpine. The lower limit of the afroalpine belt falls at about 3500 m, while the upper limit of vascular plants lies around 5000 m , and subafroalpine areas ranges between 3200‐ 3500 m. These areas include chains of mountains, mountain slopes and tops of highest mountains in the country. The highest peak in Ethiopia is Ras Dashen (4533 m a.s.l), where an alpine climate near 0°C persists all year round, sometimes even with a snow cover lasting a couple of days. However, dry lowland savannas and deserts surround this moist highland area. Ethiopia has the largest extent of afroalpine habitats in Africa (Yalden, 1983).

Montane Grassland Ecosystem

The montane grassland ecosystem is distinguished from other types of ecosystems by its physiognomy, floristic composition and ecology. It consists of herbaceous stratum usually not higher than 30 – 80 cm, very rich in perennial grasses and species of Cyperaceae, but also with sub‐shrubs and perennial herbs, among which bulbous and rhizomatous plants occur. According to White (1983), the montane grassland of Ethiopia is a derived vegetation type, although small areas of the grassland may have existed before human settlement.

Dry Evergreen Montane Forest and Evergreen Scrub Ecosystem

The Ethiopian highlands contribute to more than 50 % of the land area with Afromontane vegetation, of which dry montane forests form the largest part (Yalden, 1983). The evergreen scrubland vegetation occurs in the highlands of Ethiopia either as an intact scrub, i.e. in association with the dry evergreen montane forest or usually as secondary growth after deforestation of the dry evergreen montane forest. The Dry Evergreen Montane Forest and Evergreen Scrubland vegetations are the characteristic vegetation types of this ecosystem.

Montane Moist Forest Ecosystem

The montane moist forest ecosystem comprises high forests of the country mainly the southwest forests, which are the wettest, and also the humid forest on the southeastern plateau known as the

44

Deliverable No. 1.3

Harenna forest.The montane moist forest ecosystem is distinguished by supporting luxuriant growing epiphytes Canarina, Orchids, Scadoxus and fern plants such as Platycerium and Drynaria. Mosses also occur in the wettest portion of forests associated to major branches and barks of trees.

Acacia‐Commiphora Woodland Ecosystem

The Acacia‐Commiphora ecosystem is known for its varying soils, topography, and diverse biotic and ecological elements. These plant species are with either small deciduous leaves or leathery persistent ones. The density of trees varies from ‘high’, in which they form a closed canopy to scattered individuals to none at all forming open grasslands. The grasses do not exceed more than one meter, thus, no true savannah is formed.

Combretum‐Terminalia Ecosystem

This ecosystem is characterized by Cmbretum spp., Terminalia spp., Oxytenanthera abyssinica, Boswellia papyrifera, Anogeissus lieocarpa, Sterospermem kuntianum, Pterocarpus lucens, Lonchocarpus laxiflorus, Lannea spp. Albizia malacophylla and Enatada africana. These are small trees with fairly large deciduous leaves, which often occur with the lowland bamboo‐ Oxytenanthera abyssinica. The understory is a combination of herbs and grasses. The herbs include Justecia spp., Barleria spp., Eulophia, chlorophytum, Hossolunda opposita and Ledeburia spp. The grasses include Cymbopogon, Hyparrhenia, Echinochla, Sorghum, Pennisetum, etc. Usually the herbs dominate the ground layer at the beginning of the rainy season while grasses dominate toward the end of the rainy season.

Lowland Tropical Forest Ecosystem

The characteristic species of this forest are Baphia abyssinica and Tapura fischeri (Friis, 1992). The common species in the upper canopy include Celtis gomphophylla, Celtis toka, Lecaniodiscus fraxinifolius, Zanha golungensis, Trichilia prieureana, Alistonia boonei, Antiaris toxicaria, Malacantha alnifolia, Zanthoxylum lepreurii, Diospyros abyssinica, Milicia excelsa, Baphia abyssinica, Vepris dainellii and Celtis zenkeri.

Desert and Semi‐desert Ecosystem

It is a very dry zone vulnerable to wind and water erosion even with little or no pressure on the vegetation from grazing. The vegetation consists of deciduous shrubs, dominated by Acacia sp. interspersed with less frequent evergreen shrubs and succulents. It has very variable grass vegetation. The people of the area are pastoral and agro‐pastoral. Large scale irrigated agriculture is gaining importance in some areas of the ecosystem. This ecosystem is the extreme lowland region of the country. The flora has developed an advanced xeromorphic adaptation. Shrubs and trees have developed dwarf growth and have small, sclerenchymatic or pubescent leaves.

45

Deliverable No. 1.3

Wetland Ecosystem

Ethiopia possesses a great diversity of wetland ecosystem (swamps, marshes, flood plains, natural or artificial ponds, high mountains lake and micro‐dams) as a result of formation of diverse landscape subjected to various tectonic movements, a continuous process of erosion, and human activities. The different geological formation and climatic conditions have endowed Ethiopia with a vast water resources and wetland ecosystem including 12 river basins, 8 major lakes and many swamps, floodplains, and manmade reservoirs with a total annual surface runoff about 110 billion cubic meter

Aquatic Ecosystem

Aquatic in literal meaning refers to water. As an ecosystem, widely taken, it includes freshwater (rivers, reservoirs and lakes), marine (oceans and seas) and estuarine (coastal, bays, tidal) ecosystems. The Ethiopian aquatic ecosystem has high diversity areas such as major rivers and lakes that are of great national and international importance. The country is well known for its richness in water potential. There are about 30 major lakes that are located in different ecological zones. These lakes are situated at altitudes ranging from about 150 m below sea level high up to 4000 m. The surface area of the lakes vary considerably from less than 1 km² to over 3600 km² and mean depths range from few meters to over 260 meters. However, the major lakes that are of economic importance are concentrated in the Rift Valley.

46

Deliverable No. 1.3

6 African subregions by Barber‐James & Gattolliat

Barber‐James and Gattolliat (2012) divided the continent of Africa into five subregions foran ephemeropterological investigation. These subregions were adaptedfrom the freshwater bioregions of Thieme et al. (2005) bycombining some of their smaller bioregions to producesubregions of more or less similar area for comparison.

North Africa, although part of the Palaearctic realm due to its stronger affinities withEuropean fauna was compared withthe other subregions to provide a complete assessment ofrecorded mayfly diversity in Africa. The Sahara Desert was included with North Africa in this analysis. According to Barber‐James and Gattolliat (2012) shares Ethiopia two bioregions: mainly “Central Eastern Africa” und to a lesser extent in the northwest the “North African & Sahara Desert”.

Ethiopia shares two subregions, the “North Africa & Sahara Desert” and the “Eastern Central Africa”.

Figure 30: Sub‐regions of Ethiopia in Africa

47

Deliverable No. 1.3

7 Proposed river typology based on ecoregions and eco‐ geographic features of Ethiopia

There is a long history of organizing biological and ecological systems so that understanding can be advanced, and management principles and practice can be developed. Because of complex characteristics within river types which are related to local climate, geology, disturbance, demographic, economic and political regimes, the regional approach is the realistic one by which assessment potential can be translated into management prescriptions and application. The regional classification of streams is an interdisciplinary and applied approach, which bases on a mix of hydrobiological, geological, geographical and hydrological sciences.

Stream types serve as “units“, for which an assessment system can be applied. A stream type should always be defined on the basis of natural or near‐natural reference sites, since the comparison with undisturbed sites of a certain stream type allows defining and classifying different states of degradation. Biological assessment requires sufficiently stable, integrated stream typologies, which consider both abiotic and biotic criteria. The most prominent abiotic factors are stream morphology, geochemistry, altitude, stream size and hydrology.

The approaches to stream typology using single abiotic parameters or both abiotic and biological elements are nonexistent in Ethiopia. In such condition a “top‐down” approach is chosen on the basis of existing knowledge and classification schemes such as altitude, freshwater ecoregion, terrestrial ecoregion, and ecosystem types. Later on a “bottom‐up” approach will be applied for validation of grouping the streams/rivers. Research on the importance of scale and ecological relevance of parameters shows that even small‐scale landscape units may only partially explain the distribution of species and communities. Thus, for practical reasons one should begin with a “top‐down” typological frame‐work, which then must be verified through “bottom‐up” directed ecological analysisin order to establish a sound typology.

For a country without any stream/river typology, it is useful to apply top‐down approach for preliminary classification. This system identifies the stream types based on general landscape conditions and serves as a first basis for comparisons by providing a common starting point. To begin with top‐down approach existing broad classifications such as ecoregion, ecosystem, altitude class, geology, soil type, land use and catchment size can be considered in Ethiopian conditions as discussed above.

In regions, where stream/rivers are better known additional criteria could be applied for the further definition and description of the types (e.g. discharge, flow type, channel morphology, water chemistry, macroinvertebrate community, etc.).

48

Deliverable No. 1.3

Table 3: Examples of top‐down river typology for Ethiopian highland streams

Stream Definition of Ecoregion FWE Ecosystem Altitude (m) Catchment Size type Typology class (km2) A Alpine and Ethiopian montane Ethiopian Afroalpine and > 2500 <100 afroalpine moorlands Highlands Subafroalpine streams B Pre‐afroapine Grassland and Ethiopian Montane 2000‐2500 <200 streams woodland Highlands Grassland C Mid‐sized Grassland and Ethiopian Dry Evergreen 1800‐2500 <500 streams woodland Highlands Montane Forest and Evergreen Scrub Ecosystem D Mid‐altitude Grassland and Ethiopian Montane Moist 1500 ‐ <100 streams woodland Highlands Forest 2000 E Sandy highland Grassland and Ethiopian Acacia‐ >1500 <1000 streams woodland Highlands Commiphora Woodland

Recent study by Aschalew and Moog (2015), attempted ecoregion and ecosystem based classification of streams and rivers in Ethiopian highlands. The habitat and flow type, geology, channel morphology and catchment size were described for three ecoregion namely Ethiopian Montane Moorlands ecoregion, Ethiopian Montane Grassland and Woodland ecoregions and Acacia‐commiphora bush lands ecoregion. Based on the data obtained from this study a validation test was performed using benthic invertebrates as a biological element. Examples of stream typology

Stream type A

Streams in higher altitudes (>2500m a.s.l.) located in Ethiopian Montane Moorlands ecoregion mostly flow in V‐shaped valleys in sinuate channels. The mountains are volcanic in origin dominantly overlie Precambrian basaltic and trachytic bedrocks. The dominant substrate includes bed rocks and boulders (megalithal) and cobbles (macrolithal) whereas coarse gravel (microlithal) and sand (psammal) substrates were deposited only near the shore lines and pool sites. Human pressure in these types of streams is relatively low. Some of the floral diversity in Ethiopian Afroalpine and sub‐afroalpine include Lobelia rhynchopetalum, Rosulariasemiensis, Knifofiafloliosa, Euphorbia dumalis, Alchemilla haumannii, Alchemilla ellenbeckii, Erica aroborea, Erica trimera and Hagenia abyssinica.

49

Deliverable No. 1.3

Figure 31: Example showing stream type A in Ethiopian Montane Moorland ecoregion (Bale highlands).

Stream type B

These streams are located in Ethiopian Montane Grassland and Woodland ecoregions, where human activities are progressively increasing. Geologically, the area consists of a Precambrian basement covered in most places by thick tertiary basaltic lava flows. The substrate is dominated by megalithal, macrolithal and mesolithal. Deforestation, agricultural inputs from crop farming and cattle grazingare stressors that affect the stream system. The width ranges from 2.5 m to 18 m.

Figure 32: Example showing stream type B in Ethiopian Woodland and Grassland ecoregions.

50

Deliverable No. 1.3

Stream type C

These streams are located in Ethiopian Montane Grassland and Woodland ecoregions characterized by high and intense human activities. Geologically, the area consists of a Precambrian basement covered in most places by thick tertiary basaltic lava flows. The substrate is dominated by macrolithal in fast flowing and sloppy section, medium sized stones (mesolithal) and microlithal in slow flowing water section. Sand and fine silt substrates are dominant on sites exposed to siltation, erosion and heavy waste disposal.

Figure 33: Example showing stream type C in Ethiopian Woodland and Grassland ecoregions originated from same ecoregion.

Stream type D

These river types are located in Ethiopian woodland and grassland ecoregions but due to its dense natural forest it is classified as Montane Moist Forest ecosystem. The substrate is dominated by macrolithal covered with woody debris and mosses. Medium sized and small stones (mesolithal and microlithal) covered with course particulate organic matter. Sand and fine silt substrates are localized in adjust sites in between megalithal and macrolithal.

Figure 34: Example showing stream type D in Montane Moist Forest ecosystem

51

Deliverable No. 1.3

Stream type E

These streamtypes are located between 1500 m to 1800 m a.s.l. flow in sinuate channel type and are located in Acacia‐commiphora bush lands ecoregion and border with Ethiopian Grassland and Woodland ecoregion. The substrate is characterized by thick sand and silt layer.

Figure 35: Example showing stream type in Acacia‐commiphora bush lands ecoregion

52

Deliverable No. 1.3

8 Preliminary bottom‐up validation of proposed typology

Validation is best accomplished with reference sites that reflect the most natural and representative condition of the region. Least impacted sites (high ‐good river class according to Aschalew and Moog, 2015) are used as the basis for stream classification. Validation is used to determine whether the sampled sites should be placed into specific groups that will minimize variance within groups and maximize variance among groups. Benthic macro invertebrates from reference and good sites (according to Aschalew and Moog, 2015) were used for bottom up validation. Classification based on ecoregion, ecosystem, altitude class, catchment class were used as over lay on NMS scatter plot analysis on benthic invertebrate diversity data. Ecoregion and ecosystem basedstream classification are identified as good descriptors and from geophysical features, altitude is a major factor for scattering BMI. Other geophysical features such as soil and temperature contributed limited information which could be because of limited data used for analysis. Therefore, large biological data set will be required to test the effectiveness of geophysical features (especially geology) and existing classification schemes. Moreover temporal and spatial data are recommended in the future research to establish sound river typology that will be used for effective bioassessment in streams and rivers of Ethiopia.

53

Deliverable No. 1.3

Figure 36: Benthic macroinvertebrates distribution across least impacted sites in different ecosystems of Ethiopia (1 = Afroalpine & subafroalpine; 2 = Montane Grassland Ecosystem; 3 = Dry Evergreen Montane Forest and Evergreen Scrub Ecosystem 4 = Montane Moist Forest Ecosystem)

54

Deliverable No. 1.3

Figure 37: Benthic macro invertebrates distribution in two ecoregions of Ethiopia (1 = Afro‐alpine and sub‐afroalpine; 2 = Ethiopian grassland and woodland)

55

Deliverable No. 1.3

Figure 38: Benthic macro invertebrates distribution in four altitude class of Ethiopia (1= >2500m; 2 = 2000‐2500m; 3 = 1800‐2000m; 4 = 1500‐1800m)

56

Deliverable No. 1.3

9 References

Abell, R., M. Thieme, C. Revenga, M. Bryer, M. Kottelat, N. Bogutskaya, B. Coad, N. Mandrak, S. Contreras‐Balderas, W. Bussing, M. L. J. Stiassny, P. Skelton, G. R. Allen, P. Unmack, A. Naseka, R. Ng, N. Sindorf, J. Robertson, E. Armijo, J. Higgins, T. J. Heibel, E. Wikramanayake, D. Olson, H. L. Lopez, R. E. d. Reis, J. G. Lundberg, M. H. Sabaj Perez, &P. Petry, 2008. Freshwater ecoregions of the world: A new map of biogeographic units for freshwater biodiversity conservation. BioScience 58:403‐4.

Aschalew, L. & O.Moog, 2015. A multimetric index based on benthic macroinvertebrates for assessing the ecological status of streams and rivers in central and southeast highlands of Ethiopia. Hydrobiologia, 751:229–242.

Balarin, J. D. 1986. National reviews for aquaculture development in Africa, Ethiopia. FAO Fisheries circular.

Barber‐James, H.M. & J.L. Gattolliat, 2012. How well are Afrotropical mayflies known? Status of current knowledge, practical applications, and future directions. Inland Waters 2: 1‐9.

Beadle, L. C., 1981. The inland waters of tropical Africa. England: Longman Group Limited.

Bennun, L. & P. Njoroge, 1999. Important bird areas in Kenya. Nature Kenya, the East Africa Natural History Society, Nairobi, Kenya.

Briggs, J. C.,1987. Biogeography and plate tectonics. Amsterdam, The Netherlands: Elsevier.

Burgis, M. J. & J. J. Symoens, 1987. African wetlands and shallow water bodies. Paris, France: ORSTOM.

Butzer, K. W., 1971. Recent history of an Ethiopian delta: the Omo River and the level of Lake Rudolf, Department of Geography, Collins, R., 2002. The Nile. Yale University Press, New Haven, CT, USA.

Coulter, G. W., B. R. Allanson, M. N. Bruton, P. H. Greenwood, R. C. Hart, P. B. N. Jackson, &A. J. Ribbink, 1986. Unique qualities and special problems of the African Great Lakes. Environmental Biology of Fishes 17(3):161–183.

De Graaf, M., E. Dejen & F. A. Sibbing, 2000. Barbus tanapelagius, a new species from Lake Tana (Ethiopia): its morphology and ecology. Environmental Biology of Fishes 59(1) 1‐9.

Dgebuadze, Y. Y., A. S. Golubstov & V. N. Mikheev, 1994. Four fish species new to the Omo‐Turkana basin, with comments on the distribution of Nemacheilus abyssinicus in Ethiopia. Hydrobiologia 286 125‐128.

Dumont, H. J. 1986. The Nile River system. In B. R. Davies and K. F. Walker (Ed.). The ecology of river systems. (pp. 61‐74) Dordrecht, The Netherlands: Dr W. Junk Publishers.

57

Deliverable No. 1.3

Ethiopian Agricultural Research Organization (EARO), 1998. Annual Report of Soil Department. Addis Ababa, Ethiopia.

European Commission, 2000.Directive 2000/60/EC of the European parliament of the council of 23 October 2000 establishing a framework for Community action in the field of water policy. Official Journal of the European Communities L327, 1–72.

FAO, 1997. AQUASAT: Morocco (2001). ww.fao.org/ag/agl/aglw/aquastat/countries/morocco/index.stm).

FAO, 1999. State of the world fisheries and aquaculture 1998. FAO, Rome, Italy.

Friis, I., 1992. Forests and Forest Trees of Northeast Tropical Africa. HMSO, Kew Bulletin Additional Series XV.

Getahun, A. &M. L. J. Stiassny, 1998. The freshwater biodiversity crisis: The case for conservation. Ethiopian Journal of Science 21(2) 207‐230.

Getahun, A. 2000. Systematic studies of the African species of the genus Garra (Pisces: Cyprinidae). Unpublished PhD thesis. New York, USA. The City University of New York.

Getahun, A.,1998. The Red Sea as an extension of the Indian Ocean. In K. Sherman, E. N. Okemwa and M. J. Ntiba (Ed.). Large marine ecosystems of the Indian Ocean: Assessment, sustainability, and management. (pp. 277‐281) Cambridge, MA, USA: Blackwell Science.

Golubtsov, A.S., Darkov, A.A., Dgebuadze, Yu.Vu. & M.V. Mina, 1995. An artificial key to fish species of the Gambela Region (the White Nile Basin in the limits of Ethiopia). Joint Ethio‐Russian Biological Expedition, Addis Abeba. 84p.

Golubtsov, A.S., Dgebuadze, Yu.Yu. & M.V. Mina, 2002. Fishes of the Ethiopian Rift Valley, pp. 167‐ 258. In: C. Tudorancea and W.D. Taylor (eds.) Ethiopian Rift Valley Lakes. Backhuys Publishers, Leiden, Holland.

Harrison, A. D. & H. B. N. Hynes, 1988. Benthic fauna of Ethiopian mountain streams and rivers. Archiv für Hydrobiologie/ Supplement, 81 1‐36.

Harrison, A. D., 1995. Northeastern Africa rivers and streams. In C. E. Cushing, K. W. Cummings and G. W. Minshall (Ed.). River and stream ecosystems. (pp. 507‐517) Netherlands: Elsevier Science B. V.

Hawkes, H. A., 1975. Origin and development of the Biological Monitoring Working Party system.Water Research.vol. 32, no. 3, p. 964‐968.

Hedberg, I. & O. Hedberg, 1979. Tropical‐alpine life forms of vascular plants. Oikos 33: 297‐307.

Hering, D., O. Moog, L. Sandin & P. F. M. Verdonschot, 2004. Overview and application of the AQEM assessment system. Hydrobiologia 516, 1–20.

Hopson, A. J.,1982. Lake Turkana. A report on the findings of the Lake Turkana project 1972‐1975, Vols. 1‐6. London, UK: Overseas Development Administration.

58

Deliverable No. 1.3

Hughes, R. H. & J. S. Hughes, 1992. A directory of African wetlands. Gland, Switzerland, Nairobi, Kenya, and Cambridge, UK: IUCN, UNEP, and WCMC.

Kebede, E., G.Teferra&W. D. Taylor, 1992. Eutrophication of Lake Hayq in the Ethiopian highlands. Journal of Plankton Research 14(10) 1473‐1482.

Kleynhans, C.J. & L., Hill, 1999. Preliminary ecoregional classification system for South Africa. Department of Water Affairs and Forestry. Resource Directed Measures for Protection of Water Resources. Main author: H. MacKay. Appendix 1. Volume 3: River Ecosystems Version 1.0, Pretoria.

Lévêque C, ed., 1997. Biodiversity Dynamics and Conservation: The Freshwater Fish of Tropical Africa. Cambridge (UK): Cambridge University Press.

Manconi, R., T. Cubeddu & R. Pronzato, 1999. African freshwater sponges: Makedia tanensis gen. et sp. Nov. From Lake Tana, Ethiopia. Memoirs of the Queensland Museum, 44: 361‐367.

McClanahan, T. R. &T. P. Young, 1996. East African ecosystems and their conservation. New York, USA: Oxford University.

Mina, M. V., Mironovsky, A. N. and Y. Y. Dgebuadze, 1996. Lake Tana large barbs: Phenetics, growth and diversification. Journal of Fish Biology 48(3) 383‐404.

Mohr, P. A., 1961. The geology, structure, and origin of the Bishoftu explosion craters, Shoa, Ethiopia. Bulletin of the Geophysical Observatory, University College, Addis Ababa 2 65‐101.

Moog O., A. Schmidt‐Kloiber, T. Ofenböck & J. Gerritsen 2004. Does the ecoregion approach support the typological demands of the EU `Water Framework Directive'? Hydrobiologia, 516, 21‐33.

Nagelkerke, L. A. J. &F. A. Sibbing, 1998. A revision of the large barbs (Barbus spp., Cyprinidae, Teleostei) of Lake Tana (Ethiopia), with a description of a new species, Barbus osseensis. In Nagelkerke, L. A. J. (Ed.). The barbs of Lake Tana, Ethiopia: morphological diversity and its implications for taxonomy, trophic resource partitioning, and fisheries. (pp. 179‐214) Wageningen, The Netherlands: Wageningen Agricultural University.

Nagelkerke, L. A. J. & F. A. Sibbing, 1997. A revision of the large barbs (Barbus spp., Cyprinidae, Teleostei) of Lake Tana (Ethiopia), with a description of a new species, Barbus osseensis. In Nagelkerke, L. A. J. (Ed.). The barbs of Lake Tana, Ethiopia: morphological diversity and its implications for taxonomy, trophic resource partitioning, and fisheries. (pp. 179‐214) Wageningen, The Netherlands: Wageningen Agricultural University.

Omer‐Cooper, J. 1930. Dr. Hugh Scott’s expedition to Abyssinia‐ A preliminary investigation of the freshwater fauna of Abyssinia. Proc. Zool. Soc. Lond.Part I: 195‐207.

Omernik, J. M., 1987. Ecoregions of the conterminous United States. Ann. Assoc. Am. Geographers 77(1): 118–125.

Omernik, J. M., 1995. Ecoregions: A framework for managing ecosystems. The George Wright Forum 12(1): 35–51.

59

Deliverable No. 1.3

Roberts T.R., 1975. Geographical distribution of African freshwater fishes. Zoological Journal of the Linnean Society 57: 249–319.

Rzóska, J. 1974. The upper Nile swamps, a tropical wetland study. Freshwater Biology 4 1‐30.

Seyoum, S. &I. Kornfield, 1992. Identification of the subspecies of Oreochromis niloticus (Pisces: Cichlidae) using restriction endonuclease analysis of mitochondrial DNA. Aquaculture 102(1‐2) 29‐42.

Skelton P.H., J.A. Cambray, A. Lombard &G.A. Benn, 1995. Patterns of distribution and conservation status of freshwater fishes in South Africa. South African Journal of Zoology 30: 71–81.

Stattersfield, A.J., M.J. Crosby, A.J. Long & D.C. Wege, 1998. Endemic Bird Areas of the World. Priorities for Biodiversity Conservation. BirdLife Conservation Series No. 7. BirdLife International, Cambridge, UK. 846 pp.

Thackway, R. & I. D. Cresswell (eds), 1995. An Interim Biogeographic Regionalisation for Australia: A Framework for Establishing the National System of Reserves, Version 4.0.Australian Nature Conservation Agency, Canberra.

Thieme M.L, R. Abell, M.L.J. Stiassny & P. Skelton, 2005. FreshwaterEcoregions of Africa and Madagascar – A Conservation Assessment.Washington (DC): Island Press. 431p.

Tudorancea, C., Fernando, C. H. & Paggi, J. C., 1988. Food and feeding ecology of Oreochromis niloticus (Linnaeus, 1758) juveniles in Lake Awassa (Ethiopia). Archiv für Hydrobiologie/ Supplement 79 267‐289.

Tudorancea, C., Z. GebreMariam, &E. Dadebo, 1999.Limnology in Ethiopia. In R. G. Wetzel and B. Gopal (Ed.). Limnology in developing countries, 2. (pp. 63‐118) New Delhi, India: International Association for Limnology.

Udvardy, M.D.F., 1975. A classification of the biogeographical provinces of the world. IUCN Occasional Paper No. 18. International Union of Conservation of Nature and Natural Resources, Morges, Switzerland.

Vuilleumier, F. &M. Monasterio,1986. High Altitude Tropical Biogeography. New York: Oxford University.

Waterbury, J., 2002. The Nile Basin: National determinants of collective action. New Haven, CT, USA: Yale University.

Westphal, E., 1975. Agriculture systems in Ethiopia. Joint publication of the College of Agriculture, Haile Selassie I University, Ethiopia and the Agricultural University, Wageningen, The Netherlands.

White, F., 1983. The vegetation of Africa, a descriptive memoir to accompany the UNESCO/AETFAT/UNSO Vegetation Map of Africa UNESCO, Paris.

60

Deliverable No. 1.3

Woldegabriel, G., Aronson, J. L. &R. C. Walter, 1990. Geology, geochronology, and rift basin development in the central sector of the main Ethiopian rift. Geological Society of America Bulletin 102 439‐458.

Wood, R. B. & Talling, J. F., 1988. Chemical and algal relationships in a salinity series of Ethiopian inland waters. Hydrobiologia 158 29‐67.

WWF, 1998. A conservation assessment of terrestrial ecoregions of Africa: World Wildlife Fund, Washington, DC, USA.

Yalden, D.W., Largen, M.J., Kock, D. & J.C. Hillman, 1996. Catalogue of the mammals of Ethiopia and Eritrea. 7. Revised checklist, zoogeography and conservation. Tropical Zoology 9: 3‐164.

61