Effect of Nymphaea lotus Leaves Ash on Some Physicochemical Properties of Water and Growth of Pond Algae

Abstract

Aims: This research focuses on the effect of macrophyte ash on some physicochemical properties of water and the growth of pond algae. Study Design: Using Randomized Complete Block Design (RCBD). Place and Duration of Study: This study was conducted in the demonstration plot of the Department of Botany and Ecological Studies, Botanical Garden in the University of Uyo, Uyo, between April and June 2024. Methodology: Macrophyte ash treatments (Nymphaea lotus) applied at various concentrations (0.6 g/L, 1.2 g/L, 1.8 g/L and 2.4 g/L), arranged in three replicates each and a control. Growth was assessed using different approaches, such as spectrophotometric readings (630, 645 and 660 nm) and dry biomass of cultured algae. Physicochemical properties (pH, turbidity and conductivity) of water quality were also assessed. Results: The study reveals a significant difference at p˂0.05 in the growth of pond algae and water quality factors across all concentrations. N. lotus stimulated and enhanced algal production in all concentrations (0.6- 2.4 g/L) throughout the experiment, notably the 2.4 g/L concentration, where maximum growth stimulation was recorded. The study also reveals a similar outcome on physicochemical properties, such as pH (6.70 – 6.75), with no significant difference. Conductivity (0.18 ± 0.04 µS/cm - 1.24 ± 0.09 µS/cm) and turbidity (5.00 ± 0.00 NTU to 128.25 ± 19.30 NTU) showed a significant difference in their p-values (p ≤ 0.05). The values were comparable to World Health Organization (WHO) standard (pH: 6.5–8.5; Turbidity: <25 NTU; Conductivity: 100–2,000 µS/cm). Conclusion: While the ashes of N. lotus plant have the potential to be as a nutrient supplement in aquaculture, their application must be carefully managed to avoid negative environmental impacts.