Controlling water hyacinth (Eichhornia crassipes (Mart.) Solms): a proposed framework for preventative management

ABSTRACT Over the last century, water hyacinth, Eichhornia crassipes (Mart.) Solms, has invaded freshwater systems in more than 50 countries, causing changes in biodiversity and widespread ecological damage. It also disrupts fisheries, navigation routes, power generation, and water supply. Although water hyacinth has invaded all tropical and subtropical countries and some parts of the Mediterranean basin, recent climate change models suggest that its distribution may soon expand into higher latitudes as temperatures rise within Europe, unless effective preventative management measures are put in place. In this paper, we explore the potential ecological and socioeconomic impacts of water hyacinth invasion using well-documented case studies from Lake Victoria. We also consider the relative effectiveness of biological, chemical, and mechanical control measures on established populations. We conclude that water hyacinth is almost impossible to remove once established, and that controlling its spread into new areas is probably the most cost-effective way of reducing its impact. We propose a framework for the preventative management of this weed by combining the use of environmental DNA as an early warning system with heightened biosecurity to prevent accidental introductions and the physical removal of invasive plants before they become established. We also recommend that nutrient concentrations be lowered in waterbodies to reduce their susceptibility to water hyacinth invasion and reduce its growth rate if introduced accidentally.