Browsing by Author "Olokotum, Mark"
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Item Building Capacity for Climate Change Mitigation and Adaptation Through Mainstreaming Climate Change in Curricula of Tertiary Training Institutions in Africa(Springer, Cham, 2017) Efitre, Jackson; Natugonza, Vianny; Musinguzi, Laban; Olokotum, Mark; Naigaga, Shamim; Ogutu-Ohwayo, RichardClimate variability and change, which intensified since 1970s, are threatening natural resources and livelihoods in Sub-Saharan Africa where people depend on climate sensitive natural resources, such as agriculture and fisheries, but have limited capacity to adapt. Increasing human and institutional capacity to address threats posed by climate change to natural resources and livelihoods requires building capacity to generate and disseminate information and knowledge on climate change, its impacts, adaptation and mitigation through research, education and raising awareness by tertiary training institutions. Most tertiary training institutions in Africa have curricula covering basic and applied natural resources management but most of them do not include climate change. This paper presents a training curriculum and manual that was developed to fill this gap. The purpose of the paper is to provide in-depth information on how Climate Change can be integrated into the fisheries and aquaculture curricula of tertiary training institutions. It also provides students, scientists, practitioners, and policy makers with an understanding of key concepts and approaches to climate change mitigation measures, adaptation strategies, and policies. The aim is to mainstream climate change in fisheries training. The specific objectives are to facilitate introduction of climate change in fisheries training in Uganda that can be developed further and adopted by other countries in Africa and elsewhere; Equip students with scientific and technical capacity to anticipate and evaluate changes in climate and its influence, communicate information to stakeholders, design, and test adaptation strategies and mitigation measures; and Increase human resource capacity to address climate change issues through reviewing and strengthening of the national education system. The curriculum consists of seven modules covering: Major threats to natural resources; Introduction to climate change; Implications of climate change on aquatic productivity processes and fisheries; Implications of climate change on aquaculture; Livelihoods, impacts, adaptation and mitigation; Aquatic ecosystem modeling in relation to climate change; Principles, policies, regulations and institutions required to address impacts of climate change. The modules will be delivered through lectures, discussions, case studies and field visits. It is recommended that the curriculum and manual be incorporated into training programs of tertiary training institutions to build the capacity required to address climate change challenges particularly for fisheries in Africa.Item Characterization of Potential Threats from Cyanobacterial Toxins in Lake Victoria Embayments and during Water Treatment(Toxins, 2022) Olokotum, Mark; Humbert, Jean-François; Quiblier, Catherine; Okello, William; Semyalo, Ronald; Troussellier, Marc; Marie, Benjamin; Baumann, Kathrin; Kurmayer, Rainer; Bernard, CécileAfrica’s water needs are often supported by eutrophic water bodies dominated by cyanobacteria posing health threats to riparian populations from cyanotoxins, and Lake Victoria is no exception. In two embayments of the lake (Murchison Bay and Napoleon Gulf), cyanobacterial surveys were conducted to characterize the dynamics of cyanotoxins in lake water and water treatment plants. Forty-six cyanobacterial taxa were recorded, and out of these, fourteen were considered potentially toxigenic (i.e., from the genera Dolichospermum, Microcystis, Oscillatoria, Pseudanabaena and Raphidiopsis). A higher concentration (ranging from 5 to 10 g MC-LR equiv. L1) of microcystins (MC) was detected in Murchison Bay compared to Napoleon Gulf, with a declining gradient from the inshore (max. 15 g MC-LR equiv. L1) to the open lake. In Murchison Bay, an increase in Microcystis sp. biovolume and MC was observed over the last two decades. Despite high cell densities of toxigenic Microcystis and high MC concentrations, the water treatment plant in Murchison Bay efficiently removed the cyanobacterial biomass, intracellular and dissolved MC to below the lifetime guideline value for exposure via drinking water (<1.0 g MC-LR equiv. L1). Thus, the potential health threats stem from the consumption of untreated water and recreational activities along the shores of the lake embayments. MC concentrations were predicted from Microcystis cell numbers regulated by environmental factors, such as solar radiation, wind speed in the N–S direction and turbidity. Thus, an early warning through microscopical counting of Microcystis cell numbers is proposed to better manage health risks from toxigenic cyanobacteria in Lake Victoria.Item Fishers’ perceptions of climate change, impacts on their livelihoods and adaptation strategies in environmental change hotspots: a case of Lake Wamala, Uganda(Environment, Development and Sustainability, 2016) Musinguzi, Laban; Efitre, Jackson; Odongkara, Konstantine; Ogutu-Ohwayo, Richard; Muyodi, Fredrick; Natugonza, Vianny; Olokotum, Mark; Namboowa, Sharon; Naigaga, ShamimFisheries resources support livelihoods of fishing communities but are threatened by over-exploitation, habitat degradation, pollution, invasive species and climate change. Unlike the other threats, climate change has received limited consideration and reducing its risks requires appropriate adaptation strategies. This study used quantitative and qualitative methods to generate knowledge on fishers’ perceptions of climate change, changes in climate variables and their impacts on livelihoods, adaptation strategies, constraints to adaptation and required interventions to promote adaptation strategies that would enable fishers to build resilience to sustain their livelihoods. We found that fishers were aware of changes in climate conditions manifested by unpredictable seasons, floods and droughts. Fishing remained the main livelihood activity. However, the dominance of fishes had changed from Nile tilapia (Oreochromis niloticus L.) to the African catfish (Clarias gariepinus Burchell). Floods and droughts were associated with damage to gears, boats, landing sites and changes in fish catches and sizes, income from fishing and fish consumption. The fishers adapted by increasing time on fishing grounds and changing target species and fishing gear among other things. Some innovative fishers diversified to high-value crops and livestock. This increased their income beyond what was solely earned from fishing which provided an incentive for some of them to quit fishing. Livelihood diversification was enhanced by use of communications technology, membership of social groups, increasing fishing days and fishing experience.Item High nutrient loading and climatic parameters influence the dominance and dissimilarity of toxigenic cyanobacteria in northern bays of Lake Victoria(Journal of Great Lakes Research, 2021) Olokotum, Mark; Troussellier, Marc; Escalas, Arthur; Hamlaoui, Sahima; Okello, William; Semyalo, Ronald; Humbert, Jean-François; Bernard, CécileEutrophication of Lake Victoria led to changes in its phytoplankton communities. However, different levels of eutrophication exist in the open lake and the bays, and between embayments. This study utilized spatial and temporal sampling of Napoleon Gulf and Murchison Bay, exhibiting different trophic conditions. Over one year, we investigated phytoplankton biomass, richness, diversity and dissimilarity, and related the dynamics of the dominant species to the limnological and climatic conditions. The results confirmed that Napoleon Gulf and Murchison Bay showed large differences in eutrophication status, with lower nutrient concentrations in Napoleon Gulf than in Murchison Bay, where a strong gradient was observed from inshore to offshore areas. These nutrient dynamics resulted in a 4 to 10 fold higher chlorophyll-a in Murchison Bay than in Napoleon Gulf. From the embayments, 135 phytoplankton taxa were recorded with no significant differences in alpha diversity. However, high dissimilarity in community structure was observed in beta diversity, mostly due to a turnover among the dominant toxigenic species. Thus, from a similar species pool, there was a shift in the dominant toxigenic cyanobacteria from Microcystis flos-aquae and M. aeruginosa in Murchison Bay, Dolichospermum circinale and Planktolyngbya circumcreta in Napoleon Gulf to D. circinale in the offshore stations. These cyanobacteria are toxigenic taxa with known health hazards. Using partial least square models, we showed that both climatic variables (e.g. wind, solar radiation) and levels of inorganic dissolved nutrients (e.g. SRP, NO3 – , and NH4 + ) are the main drivers of differences and dominance in cyanobacteria communities in northern Lake Victoria.Item Implications of climate variability and change for African lake ecosystems, fisheries productivity, and livelihoods(Journal of Great Lakes Research, 2016) Natugonza, Vianny; Musinguzi, Laban; Olokotum, Mark; Naigaga, Shamim; Ogutu-Ohwayo, RichardInland fisheries are important for nutrition, employment, and income, but climate variability and change are adding to other stressors, such as overexploitation, pollution, habitat degradation, and invasive species, to threaten their productivity as well as livelihoods of fisheries-dependent communities. Understanding the whole socio-ecological system to enable communities to adapt and build resilience is therefore vital. Here, we present results froma review of the responses of African lakes, fisheries productivity, and livelihoods to climate variability and change, and provide suggestions on required policy interventions to promote adaptation and build resilience. Changes in climate variables, especially temperature, wind speed, and rainfall have contributed to changes in lake water levels, loading, and recycling of nutrients. In somelakes, such disruptions in physical and chemical conditions have triggered changes in water quality, algae and invertebrate productivity, life history of fish, and contributed to shifts in fish community composition, proliferation of invasive aquatic weeds, and changes in parasite–vector–host interactions. Fish yield has either increased or decreased depending on climatic events,with the latter negatively affecting livelihoods, and forcing affected communities to adapt. Because adaptation strategies are location specific, and influenced by local conditions, many adaptation strategies have been unguided and have negatively affected fisheries. The responses of fisheries to climate change vary among lakes of different morphometric characteristics. There is need for consistent data to examine the direction and consequences of climate variability and change on fisheries and livelihoods of specific aquatic systems, and promote location specific adaptation and mitigation measures.Item The responses of Nile tilapia Oreochromis niloticus (Linnaeus, 1758) in Lake Wamala (Uganda) to changing climatic conditions(Lakes & Reservoirs: Research & Management, 2015) Vianny, Natugonza; Ogutu-Ohwayo, Richard; Efitre, Jackson; Muyodi, Fredrick; Mbabazi, Dismas; Olokotum, Mark; Musinguzi, Laban; Naigaga, Shamim; Namboowa, SharonChanges in the catches of Nile tilapia, Oreochromis niloticus (Linnaeus, 1758), in Lake Wamala (Uganda) have been observed since its introduction. The factors contributing to these changes, however, are not well understood. This study examined changes in species composition, size structure, size at first maturity, length–weight relationship and condition factor of Nile tilapia in Lake Wamala, in relation to changes in temperature, rainfall and lake depth, to provide a better understanding of the possible role of changing climatic conditions. There was an increase in the minimum, maximum and average temperatures since 1980, but only the minimum (0.021 °C year 1) and average temperatures (0.018 °C year 1) exhibited a significant trend (P < 0.05). Rainfall increased by 8.25 mm year 1 since 1950 and accounted for 79.5% of the water input into the lake during the period 2011–2013, while evaporation accounted for 86.2% of the water loss from the lake. The lake depth was above 4 m during the years when the rainfall exceeded the average of 1180 mm, except after 2000. The contribution of Nile tilapia to total fish catch and catch per unit effort (CPUE) increased with rainfall and lake depth up to the year 2000, after which they decreased, despite an increased rainfall level. The lake depth was positively correlated with the average total length and length at 50% maturity (r = 0.991 and 0.726, respectively), while the slopes of the length–weight relationships differed significantly between high and low lake depths [t(6) = 3.225, P < 0.05]. Nile tilapia shifted from an algal-dominated diet during the wet season to include more insects during the dry season. The results of this study indicate Nile tilapia in Lake Wamala displays a typical r-selected reproductive strategy, by growing to a small size, maturing faster and feeding on different food types, in order to survive high mortality rates under unfavourable conditions attributable to higher temperatures, low rainfall and low lake water levels.Item A review of the socioecological causes and consequences of cyanobacterial blooms in Lake Victoria(Harmful Algae, 2020) Olokotum, Mark; Mitroi, Veronica; Troussellier, Marc; Semyalo, Ronald; Bernard, Cécile; Montuelle, Bernard; Okello, William; Quiblier, Catherine; Humbert, Jean-FrançoisAfrica is experiencing high annual population growth in its major river basins. This growth has resulted in significant land use change and pollution pressure on the freshwater ecosystems. Among them, the Lake Victoria basin, with more than 42 million people, is a unique and vital resource that provides food and drinking water in East Africa. However, Lake Victoria (LV) experienced a progressive eutrophication and substantial changes in the fish community leading to recurrent proliferation of water hyacinth and cyanobacteria. Based on an extensive literature review, we show that cyanobacterial biomasses and microcystin concentrations are higher in the bays and gulfs (B&Gs) than in the open lake (OL), with Microcystis and Dolichospermum as the dominant genera. These differences between the B&Gs and the OL are due to differences in their hydrological conditions and in the origins, type and quantities of nutrients. Using data from the literature, in this paper we describe the multiple ways in which the human population growth in the LV watershed is connected to the increasing occurrence of cyanobacterial blooms in the OL and B&Gs. We also described the already documented consequences of cyanobacterial blooms on food resources and fishing and on direct water use and water supply of local populations, with their potential consequences on the human health. Finally, we discuss the actions that have been taken for the protection of LV. Although many projects have been implemented in the 15 past years in order to improve the management of waste waters or to reduce deforestation and erosion, the huge challenge of the reduction of cyanobacterial blooms in LV by the control of eutrophication seems far from being achieved.