How problematic is water hyacinth as invasive species in non-eutrophied freshwaters? Towards lasting solutions of water hyacinth freshwater invasions

Abstract Water hyacinth, a plant considered highly invasive, is globally recognized for its detrimental impact on tropical freshwater ecosystems and economies. Its biology, sexual and asexual propagations, short life-cycle and abundant seed production, makes it difficult to control. Although physical removal is the common intervention, our current study in Lake Tana, Ethiopia, revealed its ineffectiveness. Despite a massive removal campaign that initially eliminated 75% (~ 1,271 ha) of water hyacinth in November-December 2020, we here show that the plant rebounded within a year, surpassing pre-intervention levels by 18%. Through SWOT analysis of various interventions, we show that short-term interventions are neither effective nor sustainable. Our analysis suggests that its proliferation in freshwaters is primarily driven by eutrophication rather than traditional mechanisms of invasion. We propose a sustainable solution centered around improving water quality through continuous removal of water hyacinth, utilizing phytoremediation to extract nutrients, and implementing catchment management to minimize nutrient influx.