ABSTRACT:Objectives: To test the effect of pig dung fertilizer on zooplankton production in research station on wetlands at the University of Abomey-Calavi in Benin. Methodology and Results: The fertilization was carried out using pig dung inside treatment T1 buckets, whereas the control medium (T0) was not fertilized. The medium was seeded with phytoplankton. Each bucket was seeded with zooplankton with initial density of 52 individual/l. The zooplankton density evolution was followed through sampling every seven days from the seeding. The trophic and physico-chemical parameters were recorded. The pig dung utilization improved the chemical properties of the medium water. That fertilization had a significant effect (p < 0.05) on plankton production. Thus, the fertilized media offered the best phytoplankton biomass and the best zooplankton maximum density of 1071 individual/l. Conclusions and application of findings: The zooplankton production is realizable with pig dung. The dynamic of zooplankton population, points out copepods dominance which are rotifers and cladocerans predators.

Different pig dung doses were used to fertilize medium production of freshwater benthic macroinvertebrates in order to test the fertilization effect and determine the optimal dose. In fact, the experiment was carried out in triplicate, for 42 days in plastic buckets. These buckets were grouped in seven treatments (T 1 , T 2 , T 3 , T 4 , T 5 , T 6 , and T 7 ) which were fertilized (respective doses of 5%, 10%, 15%, 25%, 50%, 75% and 100% with pig dung in relation to the total substrate volume) and a control (T 0 ) which was not fertilized (0% of pig dung). Each bucket was seeded in benthic macroinvertebrates with an initial density of 9 individual/dm 3 (D 0 ). The results revealed that the utilization of pig dung improved the water chemical properties in the production medium as well as the macroinvertebrates density (p < 0.05). The optimal production of the latter was obtained with the dose of pig dung applied to treatment T5 (50%), that is 150 g of dry dejections per dm 3 of substrate (150 g/dm 3 ) with a total average density of 742 ± 569 individual/dm 3 . The treatment T 5 (50%) constitutes then the dry pig dung optimal dose to be recommended for benthic macroinvertebrates production.