Geographical distribution and demography of the invasive alien aquatic plant, Hydrocharis laevigata (Humb. & Bonpl. Ex Willd.) in Zimbabwe with implications for its management

Freshwater ecosystems are increasingly threatened by invasive alien species, which outcompete native flora and fauna, disrupt ecosystem functioning, and compromise biodiversity. Hydrocharis laevigata (Amazon frogbit), a free-floating macrophyte native to Central and South America, was first recorded in Zimbabwe in 2005 and has since expanded its range across the country. This study aimed to determine the current and potential distribution, abundance, and growth characteristics of H. laevigata in Zimbabwe. Surveys conducted across 67 sites revealed the presence of the invasive alien plant at 36 sites (54%), predominantly in central Zimbabwe, with occurrences extending along the Zambezi River in the north and to Gonarezhou National Park in the south. Species distribution modeling identified high habitat suitability across most of Zimbabwe and other countries in southern Africa, with future projections indicating range shrinkage due to climate change. Demographics of the plant varied significantly across surveyed water bodies. These findings emphasise the urgent need for updated monitoring, habitat management, and integrated control strategies with a biological control component to mitigate the spread and impacts of H. laevigata, not only on Zimbabwe's aquatic ecosystems and biodiversity, but the entire southern African region.