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University of Venda (2019)

Modelling flow and water temperature in the Luvuvhu catchment and their impact on macroinvertebrate assemblages

Ramulifho, Pfananani Anania

Titre : Modelling flow and water temperature in the Luvuvhu catchment and their impact on macroinvertebrate assemblages

Auteur : Ramulifho, Pfananani Anania

Université de soutenance : University of Venda

Grade : Doctor of Philosophy in Zoology 2019

Résumé partiel
Stream flow and water temperature regimes are master variables driving river ecosystems, which determine the spatial and temporal dynamics of plant, benthic and other taxonomic groups in streams. Stream flow and water temperature trends are changing drastically worldwide with far-reaching effects on aquatic organisms. These changes are predicted to be disproportionately higher in southern Africa compared to most other regions of the world, due to declining and unreliable rainfall, increasing human population and changing land and water uses. In this study, these issues were investigated in the Luvuvhu River catchment (LRC), a strategic water source area in an arid region of southern Africa. Stream flow in the LRC is currently subjected to major forms of flow alteration, including large dams and abstraction. Studies on long-term changes in stream flow and water temperature regime are limited in this catchment. Given the fact that these rivers are home to many flow and temperature sensitive aquatic organisms such as mayflies and blackflies, the current situation in the LRC raises important concerns around the hydraulic and thermal stress of these biota. Making things worse, very few studies have assessed the constraints towards the development of conservation and management programs for rivers and their related ecosystem services in the LRC. Assessment of long-term changes in stream flow patterns, correlation between sub-daily and daily flow metrics, the influence of stream flow, water temperature and other environmental variables on both mayfly and blackfly assemblage structure and also the identification the indicator species along important environmental gradients were the main objectives of this study. This study also reviewed institutional challenges affecting the sustainable management of stream flow and river management frameworks to provide environmental flows.

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