Browsing by Author "Kaaya, Lulu Tunu"

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    Aquatic Ecosystem Services and Management in East Africa: The Tanzania Case
    (Springer Netherlands, 2015-08) Kaaya, Lulu Tunu; Lugomela, George V.
    Diverse aquatic ecosystems in Tanzania provide economically important ecosystem services. The rich supply of these services is under threat. Projections show critical water scarcity in the country by the year 2050. Demography, excessive withdrawals, land use changes, exotic species invasions and climate change that result in loss of perennial flows, eutrophication, sedimentation, and algal blooms are among the major drivers of aquatic ecosystem changes in Tanzania. Water resources uses and their management in Tanzania are mainly determined by the national macroeconomics and policies. In this review, Great Ruaha River (GRR) and Lake Victoria Basin (LVB) are used as case examples for demonstrating status, trends and drivers of ecosystem changes, and their management options in Tanzania through government and donor efforts. As a way forward, in the new Tanzania National Water Policy (NAWAPO) of 2002, Integrated Water Resource Management (IWRM) approaches as tools to ensure ecosystem protection and stakeholder’s participation have been adopted. Water for environment is given a second priority in water allocation after basic human needs. The Integrated Water Resources management and Development (IWRMD) plans currently being developed will form legal basis in management of water in an environmentally and ecosystem responsible manner. Through the IWRMD approved plans, drastic actions can be legally taken to protect and/or restore important ecosystem services in hotspot areas like the GRR.
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    Biological assessment of tropical riverine systems using aquatic macroinvertebrates in Tanzania, East Africa
    (University of Cape Town, 2014) Kaaya, Lulu Tunu
    In Tanzania, and in East Africa in general, bioassessment methods for monitoring and assessing riverine ecosystems are not yet in place. This thesis describes the development of a macroinvertebrate-based bioassessment method for assessing the degree of anthropogenic disturbance in Tanzanian rivers. The hypotheses that, 'macroinvertebrate assemblages reflect disturbance in river systems'; 'rivers with similar abiotic features have similar macroinvertebrate assemblages'; and 'spatio-temporal variation in macroinvertebrate assemblages influence bioassessment', are tested. Macroinvertebrate and environmental data were collected from the Pangani, Rufiji and Wami-Ruvu basins. Univariate analyses; constrained and un-constrained ordinations and a linear response model were used to test the hypotheses. Five important bioassessment aspects were investigated. A set of 20 criteria for screening reference sites was established and used to identify and distinguish between reference and test sites in the study area. A two-level hierarchical framework for classifying homogenous river types was developed and validated. Three river types were classified: Pangani highland uplands, central eastern Africa uplands and central eastern Africa lowlands, each with two sub-Groups. A macroinvertebrate-based biotic index, the Tanzanian River Scoring System (TARISS), was established for monitoring and assessing anthropogenically induced disturbance in Tanzanian rivers. TARISS has three metrics; number of taxa, TARISS score and average score per taxon (ASPT) for measuring disturbance. Spatio-temporal variations in macroinvertebrate taxa, assemblages and TARISS metrics were examined. Spatial variation within river types was driven by catchment characteristics such as geographical location, geology, altitude and local characteristics such as active channel width, proportions of boulder, cobble and sand on the bottom, influenced reference conditions in all three river types. Temporal variations were significant in the central eastern Africa lowlands, with higher TARISS metrics in wet than in dry periods. Biological and physico-chemical reference conditions were identified for each river type and sub-Group. Guidelines for interpreting TARISS data were established for the validated sub-Groups. In conclusion, TARISS proven to be reliable in detecting anthropogenic disturbance in Tanzanian rivers and is recommended as a national bioassessment method.
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    Ecosystem Health and Biodiversity in the Pangani Basin, Tanzania
    (Conference on Sustainable Tanzania-China Partnership, 2015-06) Kaaya, Lulu Tunu
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    Tanzania River Scoring System (TARISS): a macroinvertebrate-based biotic index for rapid bioassessment of rivers
    (NISC (Pty) Ltd and Taylor & Francis, 2015-06-22) Kaaya, Lulu Tunu; Day, Jenny; Dallas, Helen Fiona
    The biological assessment of rivers using aquatic macroinvertebrates is an internationally recognised approach for the determination of riverine ecological conditions. In this study a Tanzanian macroinvertebrate-based biotic method, Tanzania River Scoring System (TARISS), was developed in 2012, based on the South African Scoring System (SASS). Macroinvertebrate samples were collected from 101 sites, including both reference and test sites, in the Pangani, Rufiji and Wami–Ruvu basins in the Pangani highlands and central eastern Africa ecoregions. TARISS modification involved adjustments of the list of taxa and the assigning of sensitivity weightings to three new families. Six SASS taxa were excluded and three new taxa were included, resulting in a total of 96 TARISS taxa. Assigned sensitivity weightings of the new taxa were: 10 for Dicercomyzidae, 9 for Ephemerythidae and 4 for Neritidae. Through validation, TARISS proved to be reliable in distinguishing reference from test sites, based on macroinvertebrate assemblages and TARISS metrics. The degree of reliability in distinguishing reference from test sites was higher when river types were used. TARISS scores and average score per taxon (ASPT) showed stronger correlations with the disturbance gradient, and were more reliable in distinguishing between reference and test sites than the number of taxa.
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    Towards a classification of Tanzanian rivers: a bioassessment and ecological management tool. A case study of the Pangani, Rufiji and Wami–Ruvu river basins
    (NISC (Pty) Ltd and Taylor & Francis, 2015-03-10) Kaaya, Lulu Tunu
    River classification is important for reporting ecological status and for the general ecological management of river systems by partitioning natural variability. A priori river classification by abiotic variables and validation of classifications obtained using aquatic macroinvertebrates from reference sites for selected Tanzanian rivers was done in 2010–2012. A classification framework for Tanzanian rivers based on ecoregions and geomorphologic features is proposed. This gives 12, 36 and 144 river types for the whole country derived from ecoregions, ecoregion–slope classes and ecoregion–landforms, respectively. The proposed classifications were validated in the Pangani, Rufiji and Wami–Ruvu river basins using aquatic macroinvertebrates. Results suggested that macroinvertebrate assemblages reflect the differences among river types in all three regional classifications. Ecoregion–landform classification showed greater significant differences among macroinvertebrate assemblages, whereas classification by ecoregion–slope class resulted in a moderate number of river types, which include sufficient reference sites for ecological assessment.