A Ecological Baseline Surveys Of: - Lake Bisina - Nature Uganda

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5.5.3 Results A total of 36 fish species belonging to 22 genera and 7 families. Of the fish species, 36 were from the Opeta-Bisina and 10 Mburo Nakivali wetland systems respectively (Table 1). Table 1. The fish fauna of the Mburo-Nakivali and Opeta-Bisina wetland systems in Uganda 80 Wetland System Mburo-Nakivali Opeta-Bisina Family Fish species Kachera Mburo Opeta Bisina Cichlidae Astatoreochromis sp. 1 1 1 1 Astatotilapia sp 1 1 4 3 Haplochromis lividus 1 1 Haragachromis spp. 1 1 1 3 Lipochromis spp. 1 4 Marcusenius spp. 2 Oreochromis spp. 3 3 3 3 Pedicel 1 Prognathochromis spp. 2 3 Psammochromis spp. 1 1 Pyxichromis spp. 1 Tilapia sp. 1 1 1 Xystichromis sp. 1 1 Mormyridae Gnathonemus spp. 2 1 Mormyrus sp 1 Petrocephalus spp. 1 1 Ciprynidae Bagrus spp. 2 2 Characidae Brycinus sp. 1 1 Claridae Clarias spp. 2 2 2 2 Lepidosirenidae Protopterus sp. 1 1 1 Schibeidae Schilbe sp. 1 Machokidae Synodontis spp. 1 2 = 8 = 22 = 10 = 9 = 28 = 34 The species richness was higher in the Opeta-Bisina wetland system (28 and 34) compared to the Mburo-Nakivali system (9 and 10). Subsequently, the Opeta-Bisina system had species richness of haplochromines (20) than the Mburo-Nakivali system (only 3). In both systems the native tilapiine Oreochromis esculentus co-existed with the introduced Oreochromis niloticus while the former was eliminated in the main lakes where Nile perch was introduced. Ecological Baseline Surveys of Lake Bisina, Lake Opeta, Lake Mburo and Nakivali Wetlands Systems
Table 2. The Mburo-Nakivali and Opeta – Bisina wetland systems and their species of biodiversity importance. Wetland System Lake Species of Biodiversity importance Mburo-Nakivali Nakivali O. esculentus Mburo O. esculentus Kachera O. esculentus Kijanebalola O. esculentus Opeta-Bisina Bisina Haplochromines, O. variabilis Opeta O. variabilis, Haplochromines 5.6 Threats to Fish Biodiversity The threats to fish species can be grouped into five interacting categories. Over-exploitation; introduction or invasion of exotic species; pollution and eutrophication; flow modification; destruction or degradation of habitat; and climate change. Over exploitation is the result of harvesting or killing animals or plants, for food, materials or medicine, over and above the reproductive capacity of the population to replace itself. Overfishing has been the dominant threat to fish biodiversity and has devastated many commercial fish stocks. Overfishing reduces the size and genetic diversity of affected fish population. This decline has been found to reduce reproductive success and increase susceptibility of stocks to disease and environmental stresses. The problem of by catch of non-target species and under-sized juveniles of target species caught sometimes exceeds the saleable sizes. Overfishing can also lead to complete collapse of the target species and an ecosystem as a whole, termed as a trophic cascade. Collection of ornamental fish had also threatened fish diversity in Lake Bisina and Nawampasa in the late 1990s. Over harvesting of papyrus for art crafts, building and construction is another threat because it exposes the lakes to possibility of invasion of species e.g. Nile perch Pollution problems arising from land based activities contaminate the lake with heavy metals and pesticide residues. Pollution also comes from, agriculture as well as households, either by direct disposal of harmful substances into the water bodies or indirect discharges that reach the lakes via rivers. Persistent organic pollutants consumed by organisms at the bottom of the food chain get concentrated as predators eat contaminated prey. The threat of excessive nutrient enrichment is a reality. Despite the growing pollution threat there are currently no targeted efforts to reduce water pollution. Habitat degradation is brought about by an array of interacting factors. It may involve direct effects on the fish habitat such as cultivation up to the Lake margin or indirect impacts which are already evident, e.g. the high human population density in the basin leads to accelerated conversion of forests to agricultural land. The consequences of these include increased surface runoff and river sediment loads that can lead to habitat alterations such as shoreline erosion, smothering of littoral habitats, clogging of river bottoms or wetland aggradations besides destruction of refugia. Reduction in water levels in water bodies is another threat to fish diversity in the form of habitat reduction. For example historical natural water level fluctuations, due to changes of climate and river discharge may lead to a reduction of levels. The level on the coastline reduces thus reducing fish habitats in the littoral areas and posing potential negative impact on fish diversity. Ecological Baseline Surveys of Lake Bisina, Lake Opeta, Lake Mburo and Nakivali Wetlands Systems 81
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Photo: Women fishing on Lake Bisina
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ECOLOGICAL BASELINE SURVEYS OF: LAK
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Table of Contents CHAPTER 1: INTROD
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CHAPTER 1: INTRODUCTION OVERVIEW OF
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CHAPTER 2: BIRDS INVENTORY REPORT O
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2.3.2.2 Migratory classifications B
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A total of 194 species of birds wer
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Nakivali area is a refugee settleme
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and Sironko. The species list for t
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2.5.3 CONCLUSIONS AND RECOMMENDATIO
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APENDICES Appendix 1: Relative abun
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405 COMMON SCIMITARBILL Rhinopmastu
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831 BROWN-CROWNED [=HEADED] TCHAGRA
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92 MONTAGU’S HARRIER Circus pygar
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593 WHINCHAT Saxicola rubetra 3.00
Page 31 and 32: Appendix 3: Bird species list for t
Page 33 and 34: 204 TEMMINCK’S COURSER Cursorius
Page 35 and 36: 469 BUFF-SPOTTED WOODPECKER Campeth
Page 37 and 38: 833 BLACK-HEADED TCHAGRA Tchagra se
Page 39 and 40: 84 WHITE-HEADED VULTURE Trigonoceps
Page 41 and 42: 498 WHITE-HEADED SAW-WING [=ROUGHWI
Page 43 and 44: CHAPTER 3: Insects BUTTERFLY FAUNA
Page 45 and 46: 3.3.1.2 Lake Opeta Lake Opeta and i
Page 47 and 48: 3.4.1 Species Richness There were a
Page 49 and 50: weather conditions. On the other ha
Page 51 and 52: Appendices Appendix 1. Species list
Page 53 and 54: Appendix 2. Comparison of butterfly
Page 55 and 56: CHAPTER 4: Plants RAPID ASSESSMENT
Page 57 and 58: 4.1.3 Plant diversity Plants offer
Page 59 and 60: Layer Family Species % cover Life f
Page 63 and 64: 4.1.7.4 Monitoring indicators and r
Page 65 and 66: Appendix 1; Checklist of plants in
Page 67 and 68: Family Species HABIT Poaceae Brachi
Page 69 and 70: 4.3.3 Results 4.3.3.1 Lake Bisina A
Page 73 and 74: 4.3.4 Ecosystems challenges This ec
Page 75 and 76: Appendix 1: Species Checklist Famil
Page 77 and 78: CHAPTER 5: FISH RAPID ASSESSMENT OF
Page 79 and 80: 5.5 Materials and Methods 5.5.1 Stu
Page 81: Fig. 8 Mammal survey sites in Opeta
Page 85 and 86: and Kyoga lake basins. The lakes in
Page 87 and 88: CHAPTER 6: MAMMALS INFORMATION ON M
Page 89 and 90: Fig. 9 Mammal survey sites in Opeta
Page 91 and 92: 6.3.1 Lake Mburo-Nakivali wetland s
Page 93 and 94: Felidae 5 Herpestidae 6 Herpestidae
Page 95 and 96: Appendix 1: Potential list of mamma
Page 97 and 98: Order Family Common Name Species Na
Page 99 and 100: Order Family Common Name Species Na
Page 101 and 102: CHAPTER 7: WATER QUALITY WATER QUAL
Page 103 and 104: Fig. 11 Water quality survey of Lak
Page 105 and 106: Dissolved oxygen was measured using
Page 107 and 108: Turbidity Time Northings Eastings A
Page 109 and 110: References Beadle, L. C (1974) The
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A Ecological Baseline Surveys Of: - Lake Bisina - Nature Uganda

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