Belay, Yeshambel Azene2026-06-052026-06-052022https://hdl.handle.net/10566/23120The water hyacinth plant is notorious for being the world’s worst aquatic weed. In Ethiopia, it invades lake Tana which is the largest lake in Ethiopia. This is attracting attention of many researchers including mathematical modellers. To this end, in this thesis, we consider systems modelling water hyacinth effect in lake ecosystem. Among the classes of models considered in this work includes, the refuge effect of water hyacinth in lake ecosystem, the effect of water hyacinth in a lake eutrophication dynamics and singularly perturbed (slow-fast) phytoplankton-zooplankton, predator-prey systems with water hyacinth’s refuge effect.enMathematical ecologyApplied MathematicsEcosystemWeed-waterEthiopiaThesis