Mapping Invasive Aquatic Plant Distribution in River Benue, North Central and North East Nigeria

Invasive aquatic plants in the River Benue pose significant ecological and economic challenges by altering flow dynamics, reducing fish habitat quality, and impairing navigation. This study mapped the distribution and estimated abundance of invasive aquatic plant species along a 200-kilometre stretch of the River Benue spanning North Central and North East Nigeria. Boat-based surveys combined with satellite image analysis were conducted during low and high water periods. Identified invasive species included Salvinia molesta, Eichhornia crassipes, and Pistia stratiotes. Percentage surface cover was estimated using transect point sampling at regular intervals, and environmental predictors of invasion intensity were assessed. Results revealed Eichhornia crassipes as the most abundant invasive species, covering up to 35 percent of river surface at slow-flow back channels and tributary mouths. Salvinia molesta was more localised but formed dense mats in sheltered embayments. Low water periods showed higher invasion intensities, consistent with reduced dilution and slower currents. Turbid nutrient-rich water zones associated with agricultural drainage tributaries were identified as hotspots for invasive plant proliferation. The study recommends development of an integrated management plan incorporating mechanical removal at critical navigation points, biological control assessment, and reduction of nutrient inputs from agricultural catchments. Keywords: invasive aquatic plants, River Benue, water hyacinth, mapping, riparian ecology.