Invasive aquatic flora and vegetation colonizing the surface of the Ouladine lagoon in Grand-Bassam (Southeast, Côte d'Ivoire)

The proliferation of invasive aquatic plants generally indicates poor waterway health. Ouladine lagoon, which has become the receptacle for a large part of the urban waterways of the city of Grand-Bassam, is currently overrun with vast clumps of aquatic vegetation. The objective of this study is therefore to improve knowledge of the invasive aquatic flora and vegetation colonizing the bed of Ouladine lagoon. To carry out this study, phytosociological surveys of aquatic vegetation were conducted at four stations on the surface of the lagoon. Floristic inventory identified nine species of invasive aquatic plants in Ouladine lagoon, the most invasive of which are: Typha domingensis, Ipomoea aquatica, Paspalum vaginatum, Echinochloa pyramidalis, and Eichhornia crassipes. An ascending hierarchical classification (AHC) combined with an analysis of indicator species using the IndVal method made it possible to distinguish five different groups of invasive aquatic plants. The proliferation of these invasive species reflects the pollution of lagoon waters. Indeed, it is becoming urgent to insist on the implementation of measures to combat the overproduction of biomass from these aquatic plants, ecological consequences of which can have socio-economic impacts on the lives of riverside populations.