Seasonal Shifts in Microbial Communities and Physicochemical Quality of a Pristine Waterfall in Abuja, Nigeria

Abstract The effects of seasonal changes on the physio-chemical properties and microbial populations of a Pristine waterfall stream located near Veritas University, Abuja, Nigeria, were evaluated. Water samples were collected monthly for 12 months during the dry and rainy seasons. Physio-chemical parameters such as temperature, pH, conductivity, turbidity, and biochemical oxygen demand (BOD) were done by standard methods. The interaction effect of temperature and pH on the microbial organisms (heterotrophic bacteria, fungi, and yeast) and BOD was modelled using Response Surface Methodology (RSM) based on Central Composite Rotational Design (CCRD). Findings indicate that physico-chemical parameters such as conductivity (22.82 µS/cm), turbidity (0.96 NTU), and pH (8.23) as well as an increase in the number of microbial organisms were higher in the rainy season than in the dry season, however, the physico-chemical parameters values are within the acceptable range of values for freshwater systems. The relationships between temperature, pH, and microbial counts were significantly explained through quadratic models (p < 0.05) that show high fitness values (R² = 0.7622–0.9728). The significant quadratic effect of temperature on the proliferation of bacteria and fungi and significant influence of pH on yeast and BOD was noted. BOD displayed a model response change from quadratic in the rainy season to linear in the dry season. The research demonstrates that even relatively Pristine freshwater ecosystems are vulnerable to seasonal physicochemical variations that influence microbial ecology and probable public health risks. These discoveries offer a predictive framework for monitoring freshwater ecosystems under increasing anthropogenic and climate-related pressures.