Comparative assessment of Zooplankton (<i>Daphnia cucullata</i>) productivity using different fertilizers in glass aquaria

Abstract

Productivity of the Zooplankton, Daphnia cucullata in response to three different fertilizer  treatments (Poultry manure, NPK and Ammonium (Urea)) under outdoor condition in glass aquaria was studied for eight days. The objectives were to determine which of the fertilizer treatments can best enhance zooplankton (Daphnia sp) production with minimal organic particle contamination in portable glass aquarium tanks. Daphnia inoculums were isolated from mixed zooplankton population using pipette. The fertilizers were dissolved in 20 litres of tap water in glass aquaria. Three fertilizer dosages; 100 ml, 150 ml and 200 ml, each replicated twice was adopted for the experiment. Mean density of Daphnia in each tank was estimated daily·for eight days. Density was determined by direct count using standard zooplankton counting chamber under the microscope. Observed mean density was higher in poultry manure, 231 ± 132 ind. L·' (for 100 ml dose), 260 ± 162 ind. L·' (for 150 ml dose) and 315 ± 160 ind. L·' (for 200 ml dose), followed by NPK fertilizer treatment; 191 ± 76 ind L·' (for 100 ml dose), 204 ± 78 ind. L·' (for 150 ml dose) and 235 ± 92 ind. L·' (for 200 ml dose). The least count was in Ammonium treatment; 181 ± 90 ind. L·' (for 100 ml dose), 196 ± 91 ind. L·' (for 150 ml dose) and 232 ± 98 ind. L·' (for 200 ml dose). Poultry manure treatment also had higher particle contamination than NPK and Ammonium treatments. Mean particle counts for each treatment dose were; Poultry manure 5.87 ± 1.80 (for 100 ml), 4.85 ± 1.45 (for 150 ml) and 4.75 ± 1.83 (for 200 ml dose), NPK, 1.87 ± 1.13 (for 100 ml), 1.75 ± 1.38 (for 150 ml) and 2.62 ± 1.06 (for 200 ml}, Ammonium 1.25 ±_1.03 (for 100 ml), 1.50 ± 1 .41 (for 150 ml) and 2.12 ± 0.99 (for 200 ml). Though poultry manure had higher mean zooplankton production than NPK and Ammonium, the differences were not significant (P>0.05). The differences in particle count indicated significant difference (P <0.05) between poultry manure treatment and NPK and Ammonium treatment.

Key words: Zooplankton, Daphnia, Fertilizer, Production.