The Effects of Urbanization on Wetland Ecosystem and Aquatic Biodiversity in Makurdi Metropolis, Nigeria

Wetland ecosystems provide multiple benefits to human settlements, nonetheless, they are threatened by human activities associated mainly with urban growth. Therefore, the study assessed the impact of urbanization on wetlands in the Makurdi metropolis on aquatic biodiversity conservation through focus group discussion and satellite imageries. Three multi-date Landsat satellite imageries, TM of 1985, ETM+ 2000, and OLI 2020, were utilized to generate data, analyze, and monitor changes that have occurred over time and space. The Normalized Difference Built-up Index (NDBI) was adopted to extract built-up features within the study locations with indices ranging from -1 to 1. The extent of land use change (urbanization) was analyzed by subtracting the reference year (2020) from the base year. The highest rate of urban growth was observed during the third period of urbanization (2000 to 2020) in which the built-up area increased more than twice by 163.69km2 (19.81%) over wetlands. The magnitude of change in wetland areas for 35 years between 1985 and 2020 showed that wetlands decreased by -26.41 km2 representing a change (-42.97%) of the total change for the period. Wetland had an annual rate of change of -15.04% within the study years while cultivated land had the least annual rate of change (3.30%). This indicates that there was rapid urbanization in the study area between 2000 and 2020 compared to 1985 and 2000. Wetland ecosystems are under pressure in the area, and thus, have a detrimental effect on the aquatic biodiversity of the study area, through displacement, decrease, and death of aquatic species such as Crocodylusniloticus, Trichechussenegalensis, crabs, and water snails. Human activities that degrade wetlands should be reduced, restricted, or regulated.