Comparative Analysis of Organic and Inorganic Fertilizers Effects on Zooplankton Population Dynamics and Physicochemical Parameters of Culture-Media

Abstract

Efficacy of inorganic (NPK 15:15:15 and Urea) and organic (poultry-droppings) fertilizers in culturing freshwater mixed-species-zooplankton were appraised for 6 weeks, using two tanks designated Tank-A and Tank-B, treated with inorganic and organic fertilizers respectively. Mixed-species-zooplankton were obtained from the wild, nursed in indoor aquaria and used to inoculate outdoor concrete tanks for zooplankton mass-production. Physicochemical parameters cumulative-mean obtained in Tank-A and Tank-B respectively were temperature [⁰C] (25.19; 24.99), pH (7.38; 7.40), electrical-conductivity (EC) [^µs/_cm] (443.66; 387.16) and transparency [cm] (25.34; 24.66), other values (in ppm) were, total-dissolved-solids (TDS), (191.1; 209.68), total-alkalinity [TA] (108.1; 150.98), dissolved-oxygen [DO] (7.80; 5.66), BOD (2.23; 2.42), free-CO₂ (23.0; 31.0), Nitrate (4.62; 3.57), Phosphate (2.47; 2.15) and Potassium (11.49; 10.28). Three zooplankton taxa; Rotifera, Cladocera and Copepoda comprising 15 species were identified. Population density average-mean in Tank-A and Tank-B respectively were combined mixed-species-zooplankton (440 inds.ml^-1; 389 inds.ml^-1), Rotifera (208; 188 inds.ml^-1), Cladocera (129; 110 inds.ml^-1), and Copepoda (103; 91 inds.ml^-1). Population percentage distribution in Tank-A and Tank-B were Rotifera (47.37; 48.26%), Cladocera (29.28; 28.32%) and Copepoda (23.35; 23.42%) respectively. Temperature, pH, BOD and Phosphate had no significant difference (P < 0.05), while TDS, EC, TA, DO, CO₂, Transparency, Nitrate and Potassium showed significant differences (P < 0.05). Zooplankton population density also showed significant differences (P < 0.05) between the values of Tank-A against Tank-B. However, the over-all performance of both fertilizers and zooplankton response were within the optimum ranges for simulated aquatic environments’ requirements for zooplankton mass-production.