Kazinga Channel Research Articles

Long-distance swimming by African lions in Uganda.

Earth's most imperiled and iconic wildlife are facing tough decisions under increasing human pressure and limited resources. Swimming across rivers and water bodies filled with high densities of predators may be one such example. In African lions Panthera leo, previous water crossings (recorded in the peer-reviewed and gray literature, on film, and found using Google Search, and YouTube) have recorded distances ranging from <10 to 100 m, with some resulting in mortality by Nile Crocodiles Crocodylis niloticus. However, we observed a coalition of male lions swimming >1 km across Uganda's Kazinga channel located in the Queen Elizabeth National Park six times, and recorded this behavior on film on February 1st 2024. We speculate that three factors could be driving these lions to take long-distance swims with a high density of crocodiles and hippos Hippopotamus amphibius, namely (1) the lack of lionesses in this ecosystem, (2) intraspecific fights over territory with other male coalitions, and (3) the only other land connection giving lions access to the peninsula is a small road bridge with a strong human presence.

State of knowledge of aquatic ecosystem and fisheries of the Lake Edward System, East Africa

AbstractPoor and unreliable knowledge of the status of freshwater fisheries limits their inclusion in governance processes, thereby impeding effective management measures. This threatens the livelihoods of people, particularly in developing countries. Improved knowledge is required to draw the attention of policymakers and stimulate effective management measures to accelerate the sustainability of the freshwater fisheries. In line with this requirement, this paper provides the state of knowledge of the aquatic ecosystem and fisheries of the Lake Edward system, East Africa, focusing on lakes Edward, George and the Kazinga channel. The state of knowledge was accomplished by reviewing existing data and information on aspects of primary productivity and water quality, invertebrates, fish fauna, fish life history and ecology, and fisheries. The waterbodies have been monitored since the 1930s, albeit sporadically, providing data on all the above aspects but with substantial temporal gaps. Adequate and updated data and information exist on the water quality status of the water bodies, extant aquatic taxa (including fishes) and fish catches but with uncertainties in the latter. Data and information gaps exist on the abundance of biotic communities, fish life history, quantitative trophic ecology and fisheries management reference points. The aggregated data and information can directly support decisions for fisheries management. We recommend regular monitoring to fill the data and information gaps, more comprehensive stock assessments and the development of aquatic ecosystem models.

Spatial and temporal variations of dissolved CO2, CH4 and N2O in Lakes Edward and George (East Africa)

We report dissolved CO2, CH4 and N2O concentrations in two large East African lakes, Edward (surface area 2,325 km2, average depth of 37 m) and George (surface area 273 km2, average depth of 2 m). Lake George showed modest seasonal and spatial variations, and lower partial pressure of CO2 (pCO2) (26 ± 16 ppm, mean ± standard deviation), CH4 (234 ± 208 nmol/L) and N2O saturation levels (%N2O) (80 ± 9 %) than Lake Edward (404 ± 145 ppm, 357 ± 483 nmol/L, 139 ± 222 %). Surface waters in both lakes were over-saturated in CH4, and Lake George was under-saturated in CO2 while Lake Edward was slightly over-saturated in CO2. This difference was related to higher phytoplankton biomass in Lake George than Lake Edward, with average chlorophyll-a concentrations of 177 ± 125 and 18 ± 25 µg/L, respectively. Permanent high cyanobacterial biomass in Lake George led to uniform dissolved CO2, CH4 and N2O concentrations. In surface waters of Lake Edward, spatial variations of pCO2, CH4 and N2O were related to bottom depth, and locally (in particular in Katwe Bay) also related to the inputs of water from Lake George via the Kazinga Channel, a 40-km natural channel connecting the lakes. Short-term mixing events related to storms increased CO2, CH4 and N2O content in surface waters, in particular for CH4 and N2O. This indicates that mixing events in response to storms can create ‘hot moments’ for CH4 and N2O emissions to the atmosphere in tropical lakes, given the weaker vertical density gradients compared to higher latitude systems.

Common water hyacinth (Pontederia crassipes) invades Lakes Edward, George, and Kazinga Channel: A call for immediate action

Common water hyacinth, Pontederia (former Eichhornia) crassipes is a notorious aquatic invasive species. In African Great Lakes, the species is known for deleterious social, economic, and environmental impacts in lakes such as Victoria, Kyoga, Albert, Malawi, Tanganyika, Tana, and Naivasha. We report invasion and establishment of the species in Lake Edward, Kazinga Channel and possibly in Lake George. Lake Edward is one of the African Great Lakes. Common water hyacinth was observed at multiple locations on Lake Edward and Kazinga Channel. Presence of ‘mats’ of the weed with flowers is a sign of successful establishment. We observed free floating Common water hyacinth plants, indicating that the invasion is spreading. The invasion and establishment of the weed threatens a fishery of significant importance to rural livelihoods, fish species of conservation importance and tourism among others. At the current extent of invasion, mechanical removal and use of water hyacinth weevils, if expedited, could be adequate for stopping the expansion of the invasive weed. We recommend immediate action by government agencies responsible for the management of fisheries and protected areas to control the weed.

Risk factors influencing the occurrence of anthrax outbreaks at the Livestock-Game interface in Katunguru, Rubirizi district, Uganda

Anthrax outbreaks are very frequent and recurrent in the Rubirizi district in landing sites along the Kazinga channel in the Queen Elizabeth National Park in Uganda. This has persistently caused huge losses of domestic and wild animals and increased public health risks to communities. A participatory disease search (PDS) was thus conducted to identify risk factors that influence the recurrent occurrence of the outbreaks. Using PDS tools, including, Focus group discussion, Mapping, Seasonal calendars, Timelines and Pairwise ranking, local communities were engaged to recall detailed information regarding previous anthrax outbreaks. The number of persons that participated in focus group discussions ranged from 16 in Kazinga landing site to 22 in Katunguru, 18 in Kashaka landing site and 20 in Kishenyi landing site The findings revealed anthrax outbreaks had been reported previously in Katunguru, Kyabakara, Katera, Kingu and Ryeyu sub-counties of Rubirizi district that lie within or adjacent to the Queen Elizabeth National Park. The last anthrax outbreak occurred in 2014. Death of goats and sheep and wild animals, especially, hippopotami was reported in the landing sites of Kazinga, Katunguru, Kishenyi and Kashaka in Katunguru Subcounty. Uganda Wildlife Authority (UWA) established burial sites for carcasses of dead hippopotami in Kazinga and Kishenyi landing sites. Key risk factors associated with anthrax outbreaks (see attached ranks) in Rubirizi district included: (1) Frequent droughts and associated floods (2.5); (2) Dwelling in landing sites normally used as burial areas for carcasses of dead animals by Uganda Wildlife Authority (2.8); (3) Free movement of goats and sheep and intermingling with wildlife at landing sites along Kazinga channel (3.0); (4) Community habit of eating the meat of dead wild or domestic animals (3.8); (5) Communities eating not well-cooked meat (4.0); (6) Ignorance among communities regarding anthrax and its mode of spread (4.8); (7) Frequent migration of communities from landing sites with low to those with a high risk of anthrax disease (6.5); (8) Grazing domestic animals in close proximity with wildlife in the Game Park (6.8); (9) Communities consuming game meat (8.0); and (10) Frequent occurrence of anthrax outbreaks and spread of anthrax spores through floods and existing water bodies (8.3). In conclusion, the PDS case study successfully identified risk factors associated with anthrax outbreaks in Katunguru Subcounty of Rubirizi district in Uganda. Sensitization of communities on anthrax, its mode of spread and effective and sustainable control was recommended in order to contain anthrax outbreaks.

English

Parthenium hysterophorus is an alien annual herb that aggressively threatens biodiversity of Queen Elizabeth National Park (QENP) in Uganda. Occurrence, abundance and impact of P. hysterophorus on plant species diversity were examined. An observational inspection survey assessed the occurrence of P. hysterophorus while Quadrats sampled vegetation in P. hysterophorus invaded and uninvaded sites of Mweya Peninsula and along Kazinga Channel Track. Plant species richness, dominance, evenness and diversity of invaded and uninvaded sites were statistically different at P < 0.05. Species richness (R) and dominance (D) were higher in invaded sites (R = 58, D = 0.62) than uninvaded sites (P = 0.043; R = 39, P = 0.04; D = 0.46). Consequently, species diversity of other plants became less (1-D = 0.38) in invaded than uninvaded (P = 0.039;1-D = 0.55). Also, P. hysterophorus significantly starts to reduce species diversity and richness at very low levels of abundances, as low as (4.6%) and (7.7%), respectively, and dominates at a relatively higher level (40.2%). It was concluded that P. hysterophorus in QENP, negatively affects the plant species diversity at low levels of abundances through dominance. Key words: Parthenium hysterophorus, environmental impact, species abundance, species richness, weed spread.

Diversity and ecology of phytoplankton in Lake Edward (East Africa): Present status and long-term changes

Lake Edward is one of the African Rift Valley lakes draining into the Nile River basin. We conducted three sampling series in Lake Edward in October-November 2016, March-April 2017 and January 2018, in distinct seasonal conditions and in several sites varying by depth and proximity to river outlets, including the Kazinga Channel, which connects the hypertrophic Lake George to Lake Edward. The phytoplankton was examined using microscopy and marker pigment analysis by high performance liquid chromatography (HPLC) and subsequent CHEMTAX processing for estimating abundance of phytoplankton groups. Chlorophyll a concentration in the pelagic and littoral open lake sites barely exceeded 10 µg L−1 whereas, in contrast, in the semi-enclosed Bay of Katwe influenced by the Kazinga Channel chlorophyll a was up to 100 µg L−1. Despite substantial seasonal variations of limnological conditions such as photic and mixed layer depths, cyanoprokaryotes/cyanobacteria represented on average 60% of the phytoplankton biomass, followed by diatoms, which contributed ~25% of chlorophyll a, and by green algae, chrysophytes and cryptophytes. 248 taxa were identified with clear prevalence of cyanobacteria (104 taxa), from the morphological groups of coccal and filamentous species (non-heterocytous and heterocytous). The high proportion of heterocytous cyanobacteria, along with a relatively high particulate organic carbon to nitrogen (C:N) ratio, suggest N limitation as well as light limitation, most pronounced in the pelagic sites. During the rainy season, the most abundant diatoms in the plankton were needle-like Nitzschia. Comparison with previous studies found differences in water transparency, total phosphorus, and phytoplankton composition.

Baseline assessment of benthic macroinvertebrate community structure and ecological water quality in Rwenzori rivers (Albertine rift valley, Uganda) using biotic-index tools

The Rwenzori Mountains and Albertine Rift region of southwestern Uganda are part of a globally recognized biodiversity hotspot, but are currently facing pressures from intensified agriculture, mineral exploitation and hydroelectric power generation. This study was undertaken to assess the ecological water quality of Rwenzori rivers using biomonitoring metrics to determine the major factors shaping macroinvertebrate community structure in disturbed and undisturbed sites. We sampled macroinvertebrates at 66 sites along headwater tributaries and downstream areas of the Nyamwamba, Mubuku and Nyamugasani rivers, supplemented by five sites along the Kazinga channel and Lake George wetland, and identified a total of 32,579 macroinvertebrates to family level. Insecta was the most diverse taxon (45 families). Based on Average Score Per Taxon (ASPT) scores, sites were classified into four ecological water quality groups as excellent (40 sites), good (16), fair (7) and poor (8). Upstream sites had the highest abundance of pollution-sensitive families such as Caenidae and Hydropsychidae, while downstream sites had high numbers of Chironomidae. Lorenz curves revealed a low degree of evenness with Gini coefficient values ranging from 0.75 to 0.94. Ordination analysis revealed that total phosphorus, specific conductivity, chloride and chemical oxygen demand were key environmental variables contributing to variation among the sites. The majority of sites did show little to no anthropogenic influence with the exception of downstream sites. The results of this study provide useful baseline reference data, to assess and better manage the impacts of anthropogenic activities on the ecological integrity of the region’s aquatic systems. Furthermore, these datasets will advance the development of a regional family-level biotic index.

Cyanoprokatyote and algal biodiversity in the tropical Lake Edward (Africa) with notes on new, rare and potentially harmful species.

The paper presents data on the biodiversity of prokaryotic and eukaryotic algae in the tropical Lake Edward, compiled from publications of the Damas mission (1935-1936), Hecky &amp; Kling (1987) and our own results from a recent investigation of the lake phytoplankton in a three-year period (2016-2018) in the frame of the HIPE (Human impacts on ecosystem health and resources of Lake Edward) project (http://www.co2.ulg.ac.be/hipe). The provided checklist is based on modern algal taxonomy with relevant synonymizing of lists of previous authors. In total, 577 taxa from seven divisions were registered in the lake waters and in the Kazinga Channel. The richest division was Ochrophyta (287 taxa, 274 of which from Bacillariophyceae), followed by Chlorophyta (131 taxa), Cyanoprokaryota (134), Streptophyta (14), Euglenophyta (8), Pyrrhophyta (5) and Cryptophyta (1). 52 species (or only 1% of the taxa found) persisted in the lake since 30s of the 20th century till nowadays. More than half of the cyanoprokaryotes (65) are potentially toxic and harmful species. The checklist contains also data on algal abundance and frequency of occurrence, originally provided by the authors. In the phytoplankton samples, collected during the three cruises of the HIPE project, 248 taxa were found, among which the richest division was Cyanoprokaryota (104). From this total of 248 taxa, only 3 were frequent and 199 were very rare (from 1-3 samples) with 121 taxa found in one sample only. During 2016-2018, the most abundant species in the lake phytoplankton belonged to Cyanoprokaryota, Bacillariophyceae and Chlorophyta. The algae found in the lake have different ecological requirements and besides clear tropical species and some cosmopolites, some “cold water species” from northern and temperate regions were found. For them, as well as for some thermophilic species, considered alien for the lake, transport through different vectors was supposed. In the literature analyzed, 36 new taxa were described. Among them 26 taxa had Lake Edward as a single locality, and 10 were found also in other lakes and adjacent water bodies. Twelve of these new taxa were checked by modern taxonomists, but 24 still need taxonomic reconsideration.

Condition factor, Length – Weight relationship, and the fishery of Barbus altianalis (Boulenger 1900) in Lakes Victoria and Edward basins of Uganda

The condition, fishing effort and environmental parameters signify health of fish populations. This study characterized differences in water quality and fishing effort in the lacustrine and riverine systems of the River Nile, Lake Edward and Kazinga channel in Uganda. One-way Analysis of Variance (ANOVA) was used to test for differences in mean relative condition among populations in the water bodies exposed to different levels of fishing effort and water quality conditions. There were significant differences in the mean relative condition (Kn) of Barbus altianalis between River Nile (mean dif 0.0880, P <0.004) and Lake Edward and between River Nile and Kazinga channel (mean dif. 0.0796, P < 0.001). No significant difference in the mean relative condition between Kazinga channel and Lake Edward (mean diff. 0.0840, P < 0.95). Lake Edward had the highest condition (1.05), while Kazinga channel and River Nile had 1.04 and 0.96 respectively. The relationship between weight and length for each population, obtained by pooling individuals across systems was significant (P < 0.001), the length-weight allometry between the populations was also significantly different (F (2, 237) = 9.73, P < 0.001). River Nile had the highest number of fishers of 311 ± 0.88 while the number of fishers in Lake Edward and Kazinga channel were 75 ± 2.45 and 33 ± 9.12, respectively. Catch rates varied between River Nile (1.92 ± 0.59 Kg boat-1 day-1) and the rest of the systems, 6.20 ± 1.86 and 6.85 ± 1.49 Kg boat-1 day-1 in Lake Edward and Kazinga channel respectively. Water quality varied greatly across all the water bodies. Dissolved oxygen was below the minimum of 5 mgl-1 required for the physiology of freshwater fish. Conductivity was highest in Lake Edward (312 µS cm-1), followed by Kazinga channel and least in River Nile. The consistent variation in condition, fishing effort and water quality, indicates differential selective pressures faced by B. altianalis in the systems and therefore calls for concerted efforts for appropriate management measures.

Occurrence and genetic characterisation of Acanthamoeba spp. from environmental and domestic water sources in Queen Elizabeth Protected Area, Uganda.

BackgroundAcanthamoeba is an emerging potentially pathogenic amoeba that has been receiving increasing attention worldwide as a reservoir and potential vector for the transmission of pathogenic bacteria. It is also associated with brain cell damage, keratitis and skin irritation in humans. Its effects are more severe in immunocompromised individuals. This study provides for the first time in Uganda, information on the prevalence and genotypes of Acanthamoeba in environmental and domestic (tap) water.MethodsA total of 324 environmental and 84 tap water samples were collected between November 2013 and September 2014. The samples were centrifuged, cultured (Non-Nutrient agar seeded with gram-negative bacteria) and observed under a microscope. After confirmation of Acanthamoeba, genomic DNA was extracted for PCR assays by chemical lysis and purification with phenol/chloroform/isoamyl alcohol. Samples that showed the strongest positive bands (400–600 bp) were subjected to cycle sequencing.ResultsAmong environmental and tap water samples, 107 (33 %) and 36 (42.9 %) tested positive for Acanthamoeba spp., respectively. Prevalence of Acanthamoeba from specific environmental locations was as follows; Kazinga channel banks (60.7 %), Fish landing sites (50 %), River Kyambura (39.6 %) and Kazinga mid channel (5.3 %). There was a significant difference (p = 0.001) in the prevalence of Acanthamoeba between sampling sites. The mean (Mean ± SE) occurrence of the organism was higher in Kazinga channel banks (3.44 ± 0.49) and Fish landing sites (3.08 ± 0.53). Correlation between in situ parameters and Acanthamoeba was insignificant except for the Dissolved Oxygen (mg/ML) which was negatively correlated (r = −0.231, p = 0.001) to Acanthamoeba. Six distinct partial Acanthamoeba T-genotype groups T1, T2, T4, T5, T6 and T11 were obtained. Ultimately, Acanthamoeba spp., Acanthamoeba hatchetti and Acanthamoeba polyphaga were isolated in the current study.ConclusionsThere was a high prevalence of Acanthamoeba in communal piped tap and environmental water used by communities, indicating poor environmental and domestic water quality.

Distribution and phenological data of some bird species of Uganda

Abstract During a twenty five days trip in Uganda a brief faunistic survey of birds, mammals and reptiles was performed. Altogether 380 bird species were observed in six National Parks and some other protected areas in the summer of 2012. From these 64 bird species are discussed here selected according the following criteria: rarity, occurrence in a new habitat or geographic area, and emergence of novel breeding phenological data of certain species. Our new records of House Sparrow (Passer domesticus) along the Kazinga Channel (between Lake Edward and Lake George) are outside the current distribution range of the species. The House sparrow expanded its area about 800 km toward west from their first record in Nairobi in 1992. Our new records on White-tailed Ant-thrush (Neocossyphus poensis), Red-tailed Ant-thrush (Neocossyphus rufus), Papyrus Yellow Warbler (Chloropeta gracilirostris), Shelley’s Rufous Sparrow (Passer shelley) and Streaky Seedeater (Serinus striolatus) also require the correction of distribution maps of this species in Uganda. In addition we give some remarks on the breeding phenology of Mountain Wagtail (Motacilla clara), Cassin’s Grey Flycatcher (Muscicapa cassini) and Northern Red Bishop (Euplectes franciscanus). Our recent observational data of African Skimmer (Rynchops flavirostris) may have importance for the Bonn Convention. These observations might be important from conservation and ecotouristic point of views

Gastropod distribution in Lakes George and Edward, Uganda, relative to copper and cobalt levels

Published data show that Lake George, Uganda, has a poorer gastropod fauna than Lake Edward, to which it is connected through the Kazinga Channel. We conducted a study in 2001 to test whether this could be linked to copper (Cu) and cobalt (Co) loading of Lake George, resulting from previous mining activities just north of the lake. Snail and/or sediment samples collected along a transect from north of the mining site, through the runoff area from the stockpiles, Lake George, the Kazinga Channel to the northern part of Lake Edward were examined for Cu and Co content. Copper concentrations in sediment samples ranged from 3 to 855 ppm and Co from 6 to 481 ppm, being highest in the area closest to the mining activities and where the Nyamwamba River enters Lake George. About 54% of the total Cu was extractable in 20 mM EDTA, suggesting a large pool of bioavailable copper. The snail fauna was more diverse than expected, totalling 10 species, and was associated primarily with shore sampling sites, where sediment was firmer than in deeper water. Except for two species in one location, no snails were found where sediment levels of Cu were above 23 ppm and Co levels above 21 ppm, suggesting the existence of a threshold level limiting gastropod occurrence. Although the occurrence of snails was negatively related to Co level, there was no correlation between concentrations of Cu and Co in snail tissue and those in the sediment.

Managing the 2004/05 anthrax outbreak in Queen Elizabeth and Lake Mburo National Parks, Uganda

AbstractIn August 2004, hippo mortality in the waters of Kazinga Channel, Lakes George and Edward within Queen Elizabeth National Park (QENP) was observed. Veterinary investigation confirmed the disease killing hippos to be anthrax, using clinical, postmortem and laboratory diagnosis, including the polymerase chain reaction technique. Anthrax is believed to have occurred in QENP in 1959, 1962 and 1991 amongst Hippopotamus amphibious but these was not as devastating as the outbreak of 2004–2005. During the outbreak, 306 hippopotami representing 11.63%, 63 zebras representing 1.47%, 60 buffaloes representing 0.9%, thirteen warthogs representing 0.69%, twelve kobs representing 0.07%, three waterbucks representing 0.09% and five elephants representing 0.02% died. A multisectoral National Taskforce was set up, to among other things contain the disease at source and halt its spread. Carcass disposal by burying and burning, decontamination of disposal sites by 10% formaldehyde, ring vaccination of cattle and sheep using blanthrax vaccine and community sensitization, were carried out by the taskforce. A surveillance programme is in place.

Facies Architecture of Flexural Margin Lowstand Delta Deposits in Lake Edward, East African Rift: Constraints from Seismic Reflection Imaging

Abstract Lake Edward is single half-graben rift basin unique in the East African Rift System as a result of its connection to Lake George via the Kazinga Channel, a paleo–river valley which is incised into the flexural margin of the lake. Using recently acquired normal-incidence seismic reflection data and thirty-three lake-bottom sediment samples, we examine the consequences of this hydrologic connection for understanding depositional processes and facies development along the flexural margin of Lake Edward. Three depositional sequences were defined in the study area based on top and bottom discordances of seismic reflections. Climatically induced changes in lake level appear to have forced sequence development. Sequence I deposits indicate that highstand conditions prevailed earlier in the Pleistocene. Evidence for high-frequency lake-level change comes from lowstand delta clinoforms in two separate stratigraphic intervals on the flexural margin. An older lowstand event occurred during Sequence II time and reduced lake level by at least ~ 37 m. A younger lowstand event occurred during the deposition of Sequence III and reduced lake level by ~ 18 m. Clastic sedimentation on the flexural margin of Lake Edward is strongly modified by inflow from the Kazinga Channel and Lake George during periods of lowered lake level. We suggest that the presence of an incised valley at the margin of the rift controls the stratigraphic development of clinoforms diagnostic of lowstand deltaic sedimentation. The morphology and orientation of these clinoforms suggest that discharge from Lake George during arid periods utilized the Kazinga Channel to transport sediment toward the exposed flexural margin of Lake Edward. Dipping reflections in sigmoid-oblique clinoforms suggest that these flows were capable of transporting sediment loads that included coarse grain sizes. Deposition by this process occurred several times during the late-Quaternary history of Lake Edward, and represents an important modern analogue for linked incised valley-lacustrine delta sequences in the stratigraphic record.

Heavy metals in Lake George, Uganda, with relation to metal concentrations in tissues of common fish species

The northern end of Lake George, Uganda, and its associated wetlands receive localized metal pollution from a former copper mine and tailings left after metal extraction. The aim of this study was to determine (i) whether the heavy metals are a threat to the biology of the major commercial fish species and (ii) whether consumption of the fish threatens human health. Concentrations of copper, zinc, cobalt and nickel in detrital sediments, plankton, and five fish species from sites in Lake George, the Kazinga Channel and Lake Edward (which are inter-connected) were determined using atomic absorption spectroscopy. The detrital sediments of Hamukungu Bay, Lake George, had average concentrations (μg/g dry weight) of 96.3 zinc, 270.4 copper, 57.4 cobalt and 42.8 nickel. There were no significant differences between the Hamukungu Bay and the North Lake George site of Bushatu: both receive inflows from the mining activities. Concentrations of copper and zinc were significantly higher than background values from unpolluted freshwater ecosystems. Plankton samples showed a metal concentration gradient consistent with a gradient from the source of pollution in northern Lake George, along the Kazinga Channel to Lake Edward. The liver tissues of fish had markedly higher concentrations of copper and zinc than flesh. Concentrations of cobalt and nickel were relatively low. The highest mean concentrations of metals in liver tissue occurred in Oreochromis leucostictus (189.0 μg/g Cu) and Bagrus docmac (187.5 μg/g Zn) whilst the lowest occurred in Oreochromis niloticus (15.3 μg/g and 78.2 μg/g dry weight copper and zinc, respectively). However, O. niloticus contained the highest concentrations of cobalt (11.2 μg/g) and nickel (3.8 μg/g). Liver Somatic Indices (LSI) of the fish species from the different sites indicated a reduction of LSI in those fish from the most contaminated zones of northern Lake George compared with all other sites. This suggests there could be anatomical and physiological abnormalities linked to the heavy metal pollution. The flesh had only low concentrations of metals; well within international guidelines for consumption. A person would have to consume 9 kg of fresh flesh of Clarias sp. and 65 kg of O. leucostictus daily to exceed the WHO recommended intake for copper, and even more for other metals. This implies that currently metal pollution in Lake George presents an ecological rather than a human health concern.

Basin neotectonics of Lakes Edward and George, East African Rift

The Edward and George lake basins are located in the western branch of the East African Rift System (EARS). Both basins occupy half grabens with the main boundary fault located in the west and are separated by a high relief accommodation zone. This structural high formed where the NNE–SSW trend of the Miocene rifting and NW–SE oriented basement lineaments interfere. The Kazinga Channel, connecting Lake George to Lake Edward, cuts across this uplifted area. The course of the channel has been affected by syn- and antithetic faulting. Volcanism in this part of the EARS is related to high relief accommodation zones, and volcanic craters are either parallel to the NW–SE oriented Precambrian lineaments or the NNE–SSW oriented Miocene rift. Volcanism that initiated during the early stages of rifting commonly parallels the NW–SE oriented accommodation zones and basement lineaments, while craters that formed during the later stages of rifting tend to parallel the large border faults of the NNE–SSW oriented rift. Rifting processes in the Edward and George basins have been disturbed by uplift mechanisms related to the Rwenzori horst block formation. The Kasindi Fault Zone located in the central part of the Edward Basin is related to a low relief accommodation zone formed between two opposite dipping border faults. The Edward–George basin is tectonically active; the large boundary faults, the syn- and antithetic faults of the rift basin, and the accommodation zones all show signs of recent movement. Faulting related to the Kasindi Fault Zone suggests a >12 m fault movement during the Holocene, possibly related to periods of extensive volcanism within the Toro Ankole volcanic province.

Diurnal activity patterns of three heron species in Queen Elizabeth National Park, Uganda

Kasoma, P.M.B. 2000. Duirnal activity patters of three heron species in Queen Elizabeth National Park, Uganda. Ostrich 71(1): 127–130. Observations of activities were carried out over 12 h periods on the Goliath Heron, Grey Heron and Great White Egret along the shores of Lake Edward and Kazinga Channel. Behaviour was classified into three major categories: foraging, loafing and other behaviour. For all three species, foraging went on throughout the daylight hours but the level was variable both in the dry and wet seasons and between species. For all three species, foraging basically consisted of standing-and-waiting. The Great White Egret spent more time foraging than the other two species. Overlap between species in foraging activity on an hourly basis was high during most hours of the day implying that ecological separation through temporal partitioning of daylight hours is negligible.

Population density and intra‐ and interspecific competition of the African Fish Eagle Haliæeetus vocifer in Kyambura Game Reserve, southwest Uganda

Population density and intra‐ and interspecific competition of the African Fish Eagle Haliæeetus vocifer were studied in Kyambura Game Reserve, southwest Uganda. Density varied significantly between 1.75 and 3.25 individuals per km of shore for the breeding biotopes along the Kazinga Channel and crater lakes and between 0.45 and 0.58 for unsuitable biotopes such as the Kyambura Gorge or the bush grassland. The age‐class distribution showed extremely high percentages of immatures in these unsuitable biotopes (50–95%) as a consequence of intraspecific competition for space and food. Some immatures survived in the bush grassland, feeding on lion and leopard kills and very possibly on birds. Each territory was up to five times larger than breeding pair territories along the Kazinga Channel (5.1 km2 in comparison with 0.9 km2). Interspecific competition for space was likely between immature African Fish Eagles and other species of raptors. Ecological segregation with regard to space was assessed between these species in the bush grassland.

Plankton identified in Stomach contents &lt;i&gt;Oreochromis niloticus &lt;/i&gt;(Pisces: CICHLIDAE) and the water system of Lakes Edward, George, and Kazinga Channel – Uganda

The samples were collected from Lake Edward at Rwenshama, Kisenyi and Katwe, and from Lake George at Mahyoro, Kashaka and Kasenyi and in Kazinga Channel at Katunguru. The organisms identified from the water samples obtained irrespective of station or depth were mainly the phytoplankton (diatoms, blue-green algae and green algae). Of the phytoplankton, blue green-algae were the most abundant both in quantity and number of species especially in L. George. In order of importance were Microcystis spp, Planktolyngbya spp and Anabaenopsis spp were the dominant blue greens. Diatoms and green algae were present but less abundant. The estimated proportions of different types of phytoplankton identified in O. niloticus stomach contents indicate that bluegreen algae were the most abundant followed by the diatoms and green algae.