Assessment of Soil Quality along the Proposed Main Road through Ngorongoro and Northern Serengeti, Tanzania

A new road through northern Serengeti National Park is proposed to be built. The purpose of this study was to collect baseline data on soils along the route of the proposed road before its construction. The physicochemical properties were used to characterize the soil before the construction of the proposed road. Levels of soil macro-elements mainly potassium (K), calcium (Ca), magnesium (Mg) and sodium (Na), and physicochemical properties: electrical conductivity (EC), pH, organic carbon (OC), soil organic matter (SOM), total nitrogen (TN), cation exchange capacity (CEC), phosphorus (P), aluminium (Al) were determined. Also, heavy metals: cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), lead (Pb), manganese (Mn), mercury (Hg), nickel (Ni) and zinc (Zn) were analyzed. This study was done on the eastern (Ngorongoro District) and western (Serengeti District) segments of the proposed road. The ranges in average values obtained for the physicochemical parameters and metal concentrations in the soils were: 0.05–0.57 mS/m for EC, 6.5–7.9 for pH, 0.71–1.23% for OC, 0.30–0.74 g/kg for TN, 1.23–2.12% for SOM, 20.6–79.7 mg/kg for available P, 0.27–2.08 meq/100-g for available K, 9.89–30.3 meq/100-g for available Ca, 0.29–0.67 meq/100-g for available Mg, 0.06–1.35 meq/100-g for available Na, 11.04–33.12 meq/100-g for CEC, 46702.9–63963.3 mg/kg for Al, BDL for Cd, 24.70–101.55 mg/kg for Cr, 27.31–34.96 mg/kg for Cu, 32390.8–42439 mg/kg for Fe, 18.06–22.19 mg/kg for Pb, 957.1–1458.9 mg/kg for Mn, BDL for Hg, 20.24–32.52 mg/kg for Ni and 96.09–124.14 mg/kg for Zn. These observed levels indicate that the soils before road construction are unpolluted, moderately fertile and within the specifications of good agricultural soil. On the western segment of the proposed road, the soil will need application of fertilizers for better agricultural usage. Keywords:    Physicochemical properties; soil quality; total nitrogen; macro-elements; heavy metals

The importance of Water Quality and Quantity in the Tropical Ecosystems, Tanzania

This thesis looks at the importance of water quality and quantity in the tropical ecosystems in relation to movement of animals who depend on that water for their daily lives and existence. Seasonal fluctuations of rainfall were pronounced, with marked wet and dry seasons. Surveys of water quality in the surface waters in the Serengeti and Tarangire National Parks in Tanzania, East Africa were undertaken throughout the year, in both the wet and dry seasons, from 1996 to 2003. Surveys of water quality in the surface waters of Tarangire National Park were carried out from 1999 to 2001. In the Serengeti most of the rivers were ponded, with ponds having a flushing time of 1 month in the wet season and zero flushing in the dry season. The parameters used in the water quality included temperature, pH values, dissolved oxygen (DO), salinity (S) and visibility. pH values varied spatially from extremely alkaline conditions (pH>10) in the southern plains of the Serengeti to acidic conditions in the northern region (pH=5.9). In the southern plains at the end of the dry season the salinity of the surface waters was high (5-100/00) while there was still abundant fodder, the zebras and wildebeest had started to migrate away, suggesting that excessive salinity may be the trigger initiating the annual migration. Most surface waters were heavily eutrophicated as a result of animal dung. Because of this animal dung, the dissolved oxygen concentration near the surface fluctuated widely between 1 and 200% of saturation, the smaller values occurring deeper in the water column. Stirring and mechanical aeration by various animals in the water prevented the formation of anoxic conditions. The oxygen stress was less in wetlandfringed water bodies, because of the filtering effect of wetlands. Light penetration was high (>10 cm) in saline waters because of settling of suspended matter was accelerated by flocculation caused by bacteria and vegetation detritus. Elsewhere, the euphotic zone was less than 1 cm thick and the waters generally inhospitable to aquatic life. Tarangire National Park, on the other hand, showed similar situation as in the Serengeti. In the dry season, the only drinking water available for wildlife was the Tarangire River and a number of small, scattered wetland-fringed water holes. The salinity was often high (>8 ppt) and was higher in the dry years than in wet years, as well as at the start of the wet season. Water quantity and quality also appeared to control the annual migration of wildebeest, zebras, elephants and buffaloes. These animals aggregated in the dry season in areas with the least salty water. The timing of seasonal variations in rainfall was largely predictable and controlled annual migration. All wildebeest and most zebras migrated out of Tarangire National Park and into the wider Tarangire ecosystem at the start of the wet season, and they returned into the park in the dry season. Some elephants and buffaloes also migrated in and out of the park and a larger resident population remained, whose size may vary interannually depending on surface water quantity and quality. The extent of the migration zone may also vary interannually. The study also focused at the vertical distribution of temperature and dissolved oxygen over 24 hours in a pond of the Seronera River inhabited by hippos in the Serengeti. Findings showed that the waters were very turbid (visibility <2 cm). The high turbidity was from animals trampling sediment and a permanent surface algal bloom sustained by faecal matter. Direct solar heating was restricted to the top few centimetres. This resulted in a strong thermal and density stratification inhibiting aeration of the water column. Waters at the mid-depth were aerated only when hippos stirred the water. Anoxic conditions were common in bottom water; these were occasionally ventilated in day time by mixing due to bottom heating from decaying organic matter and at night by convective cooling. Poor water quality in hippo pools may affect wildlife. In the Serengeti ecosystem, the Mara River is the only source of permanent water supply throughout the year. Other rivers such as the Grumeti and Mbalageti dry out in the dry season with only pools of water scattered in a series. The Mara River catchment is the dry weather refuge for more than 1 million wildebeest and zebras of the Serengeti ecosystem. The Mara River flow is affected by developments in Kenya, including deforestation, water diversion for irrigation, and the proposed Ewaso Ng’iro (South) Hydropower project. An ecohydrology model was developed to predict the inter-annual fluctuations of the wildebeest and lion populations as a function of the hydrology. The model was calibrated against observations of rainfall and wildebeest and lions numbers in the period 1960-2000. This model used to predict the likely impacts of these developments on the Serengeti ecosystem. The model was forced by observed monthly rainfall in the period 1900-2000 and calibrated against observations of the number wildebeest and lions also in the period 1960-1999. The projects are predicted to have little effect on the number of migrating wildebeest in the Serengeti until a drought occurs; historically a drought occurs about every 7 years, and a severe drought occurs every 15 years. At that time 20-80% of the migrating wildebeest may die, according to the severity and duration of the drought. With a 50% die-off, it may take twenty years for the population to recover; with an 80% die-off there may be no population recovery. In practice the economic benefits would go to Kenya while Tanzania would suffer most of the economic costs, i.e. the negative impact on the tourist industry and socio-economic benefits to communities living along the Mara River. To ensure sustainable developments for both Kenya and Tanzania, a transboundary Mara River Management Plan needs to be implemented and be compatible with ecohydrology principles for the sustainable use of aquatic resources

The influence of wetlands in regulating water quality in the Seronera River, Serengeti National Park, Tanzania

The distribution of temperature, salinity, visibility and dissolved oxygen was sampled from 1996 to 2002 at sites along the Seronera River. The minimum temperature decreased with distance upstream. The salinity increased up-river where occasionally hypersaline conditions prevailed. Dissolved oxygen was highly variable spatially and temporally, depending on both the level of eutrophication by animal dung and the presence of wetlands that help filter the excess nutrients. During the study period, fringing, freshwater wetlands have generally been degraded and in some cases destroyed, and this has been accompanied by significantly decreased oxygen levels, sometimes nearing anoxic conditions. Also during this period, saltwater\ud wetlands have increased, and since wildlife impacted these wetlands little, dissolved oxygen levels remained high throughout. Visibility was highest in areas fringed by wetlands

Ecohydrology as a tool for the survival of the threatened Serengeti ecosystem

The results of 10 years of monitoring water quality and quantity during the period 1996-2006 in the three rivers (Mbalageti, Grumeti and Mara) draining the Serengeti ecosystem are presented, together with river gauging data starting in 1948, rainfall data starting in 1960, and animal population data starting in 1960. Water quality remained unchanged in the Mbalageti and Grumeti rivers; these rivers are seasonal and they dry out during a drought. The Mara River is perennial and is vital to maintain the ecosystem during a drought. Its quality has changed, with increased contribution from groundwater, with higher pH and visibility and decreasing salinity. The flow rate during a drought has decreased by 68% since 1972. This is attributed to deforestation of its upper catchment in the Mau forest in Kenya and to extraction of water for irrigation in Kenya upstream of the ecosystem. Hydrological modeling suggests that the Mara River would now dry out for two months and one month respectively if the 1949-1952 and the 1972-1973 severe droughts occurred again. Ecohydrologic modeling suggests that this would in turn lead to the collapse of the herbivore population from the lack of drinking water. This model also suggests that providing drinking water to the animals at artificial water holes spread throughout the ecosystem would lead to decadal time-scale booms and busts of the herbivore population. The Serengeti ecosystem stability is maintained by the annual migration that partitions the ecosystem in seasonally used compartments. It is thus necessary to restore the natural hydrology of the Mara River in Kenya, and this requires remediation measures in Kenya. If that does not occur, disaster prevention measures are needed by providing water in weirs, dams, and artificial wetlands along the Mara River in the Serengeti National Park, as well as extending by 5 km the western edge of the park so as to reach Lake Victoria to provide acces to permanent water

Ecohydrology-based planning as a solution to address an emerging water crisis in the Serengeti ecosystem and Lake Victoria

[Extract] The Serengeti ecosystem is often taken to be the 25000 km2 animal migration area (Figure 1a). This includes the 14,763 km2 Serengeti National Park (SNP), the Masai Mara Reserve in Kenya, and a number of game controlled areas that form a buffer zones, principally the Maswa, Ngorongoro, Loliondo, Ikorongo, Grumeti, and the Speke Gulf Game Controlled Area (SGGCA) that, although tiny (95 km2), is potentially important because, if human encroachment was removed, it would provide access for wildlife to the permanent waters of Lake Victoria (Figure I b). However this definition of the ecosystem ignores the hydrology. The Serengeti ecosystem has only one perennial river, the Mara River. The Mara River, together with a few scattered springs in the northern region of the SNP, is the only source of water for migrating wildlife in the dry season in a drought year. Thus the source of Mara River water in the dry season, namely the Mau forest in Kenya's highlands, is also part of the Serengeti ecosystem even if the migrating animals do not migrate to that area (Gereta et al., 2002 and 2009)

The role of wetlands in wildlife migration in the Tarangire ecosystem, Tanzania

Twenty-two years of rainfall data from six sites, 5 years of animal migration data and 2 years of water quality at 13 sites were explored to quantify the role of water in the Tarangire ecosystem. Inter-annual fluctuations in rainfall were large and not predictable solely from the Southern Oscillation Index. Seasonal fluctuations of rainfall were pronounced, with marked wet and dry seasons. In the dry season, the only drinking water available for wildlife was the Tarangire River and a number of small, scattered wetland-fringed water holes. Their salinity was often high (>8 ppt) and was higher in dry years than in wet years, as well as at the start of the wet season. Water quantity and quality may control the annual migration of wildebeest, zebra, elephants and buffaloes. These animals aggregate in the dry season in areas with the least salty water. The timing of seasonal variations in rainfall is largely predictable and controls annual migration. All wildebeest and most zebras migrated out of Tarangire National Park and into the wider Tarangire ecosystem at the start of the wet season, and they returned into the park in the dry season. Some elephants and buffaloes also migrated in out of the park and a larger resident population remained, whose size may vary inter-annually depending on surface water quantity and quality. The extent of the migration zone may also vary inter-annually