Quantifying the effects of water hyacinth (Pontederia crassipes) on freshwater ecosystems: a meta-analysis

Water hyacinth (Pontederia crassipes, used to be Eichhornia crassipes), one of the world's most notorious invasive species, poses significant threats to freshwater ecosystems worldwide. Despite its widespread presence in over 70 countries, there is a lack of comprehensive analyses about the impacts of water hyacinth. To fill this knowledge gap and to explore the multi-dimensional (physical, chemical, and biological) impacts of water hyacinth on freshwater ecosystems, we conducted a meta-analysis that synthesized data from 25 original studies encompassing 12 countries and three continents. We found that water hyacinth invasions lead to significant reductions in water dissolved oxygen levels (Standardized Mean Difference (SMD) = −2.26, 95% CI: [−3.94, −0.56]; p = 0.001) and nitrogen (SMD = −1.70, 95% CI: [−3.19,  − 0.20]; p = 0.01). We also observed non-significant but notable trends of decreased water pH levels and increased macroinvertebrates abundance, suggesting complex interactions between water hyacinth and abiotic factors. Our analysis underscores the need for more localized studies to better understand the general impacts of water hyacinth invasions. Given the significant ecological disruptions caused by water hyacinth, effective management strategies are imperative to mitigate the adverse effects of this invasive species. Overall, this meta-analysis provides valuable insights into the ecological consequences of water hyacinth invasion, highlighting the urgent need for targeted research and intervention strategies to protect and restore affected freshwater ecosystems.