Laboratoire d’Environnement et de Biologie Aquatique (LEBA), UFR des Sciences et Gestion de l’Environnement, Université Nangui Abrogoua, 02 BP 801 Abidjan 02, Côte d’Ivoire
A feeding study was conducted at the NANGUI ABROGOUA University fish farm between August and September 2022. It assesses the effects of one an imported extruded diet (KOUDIJS) used as a reference (AR) and three practical diets (ACOP, ACOT and MA), on growth and cost-benefit ratio. These diets contain 30% protein. The basic composition of formulated diets is: ACOP (coconut and soybean oil cakes, rice and wheat bran, vegetable oil); ACOT (cotton seed and soybean oil cakes, rice and wheat bran, vegetable oil) and AM (Cotton seed, coconut and soybean oil cakes, rice and wheat bran, vegetable oil). Larvae weighing 145 mg ± 6 were fed to satiety in 8 aquariums at the density of 4 larvae/L. The larvae were fed at 9h, 11h, 13h and 15h. After 35 days of rearing, the final average weights obtained were 1.45 ± 0.01g, 1.51 ± 0.01g and 1.67 ± 0.01g, respectively for ACOP, AM and ACOT, against 1.85 ± 0.06g for AR. The best feed conversion index (CI= 1.31 ± 0.04) and daily growth (1.71 ± 0.06g/day) were obtained with AR, followed by ACOT. The highest feed conversion index (CI= 1.68 ± 0.01) and lowest daily growth (1.33 ± 0.00g/day) were recorded with ACOP. Compared to AR, formulated diets reduced feed cost per unit weight gain by 66-71%.
A study of microalgae of the Bandama River was carried out from samples taken from February to October 2013 using 20 μm mesh wide plankton net. This study uses a light microscope and Scanning Electron Microscope (M.E.B.) which allows a better observation of the fine structure of the walls of the organisms. Seventy-five (75) taxa were identified, distributed among 27 genera, 13 families, 4 order and 2 classes. Among these, 12 taxa are mentioned for the first time in the algae flora of Côte d'Ivoire. This study contributes to increase our knowledge on Chlorophyta. Results of this study can be used for teaching and algae taxonomy studies.
This study highlighted the symbiosis between Anabaena-azollae cyanobacteria and Azolla aquatic fern in the production of Azolla filiculoides and its use as a biofertilizer. His trial of vegetative production using ordinary water + dung, carried out in 14 days of culture, showed a significant amount (6473g). Then, the use of this one as an amendment for the growth of CB-one rice, showed its positive impact on soil fertility thus translating high yields of CB-one rice contrary to the unamended witness. Indeed, with this treatment, the average number of tillers observed after 56 days of culture, was 18.1 ± 4.23 tillers contrary to the NPK (15.83 ± 4.98) and the control (10, 4 ± 3.27). The average number of leaves was significant in Azolla (57.20 ± 13.45), average for the NPK fertilizer (48.86 ± 15.79) and low for the control (34.83 ± 14, 52). In sum, the trays treated with Azolla filiculoides produced many more panicles and grains compared to treatments. As a result, Azolla is likely to restore soil fertility by providing the soil with the nutrients needed for crop productivity.
Phytoplankton abundance in relation with physico-chemical parameters were investigated at 11 stations monthly from May 2014 to april 2015 in Aghien lagoon. Distribution of phytoplankton abundance had homogeny within the entire lagoon. However it notices differences between seasons. The high abundance was recorded in the low rainy season (2.3 107 cells/mL) and the low one in the high dry season (1.1 107 cells/mL).The seasonality is confirmed by Indicator value and RDA. Three groups were determined according seasons. The high rainy season assemblage was influence by conductivity and high temperature. Ammonium, BOD, dissolved oxygen and pH influence species of low dry season. Concerning the group 3 (high dry season and low rainy season), abundance of species is associated to high value of turbidity and nitrate. Indeed, the phytoplankton community of Aghien lagoon is still dominated by Cyanobacteria such as Microcystis wesenbergii (Komarek.) Komarek., M. aeruginosa (Kützing) Nägeli., Microcystis sp., Aphanocapsa incerta (Lemm.) Cronb. & Kom. and Anabaena circinalis Rabenh.ex Born. & Flash. These species are responsible for different blooms recorded in the Aghien lagoon. It also important to identified the kind of toxins these bloom-forming cyanobactorial produce in this lagoon.
To assess the influence of the breeding structure on the effectiveness of sexual inversion, growth performance and economic returns of Bouaké strain of Nile tilapia Oreochromis niloticus, hormonal treatment with 17-α-méthytestosterone was performed snapped installed in concrete basin (lot I), in happa) implanted in earthen pond (lot II) and concrete basin snapped without (lot III). The success rate of sexual inversion is 100% male in the three lots. The final average weights recorded were 2,35 ± 0,24 g (lot II), 2,06 ± 0,72 g (lot I) and 1,53 ± 0,65 g (lot III). The daily growth and the specific growth rate significantly different only between the Lot II and Lot III. The survival rate, the nutrient ratio and condition factor were not affected by the farming structure. The cost of producing a fry of 5 g recorded for Lot III (19,82 ± 0,40 F CFA) was significantly (p <0,05) higher than that obtained in the lot II (14,59 ± 1,49 CFA) and to that noted in the lot I (16,12 ± 0,10 F CFA). Profitability indices are 2,4 ± 0,25 for Lot II, 2,17 ± 0,12 for Lot I and 1,76 ± 0,25 for Lot III. The best results were recorded at the happas implanted pond followed by those installed in concrete basin.