Etude comparative des macroinvertébrés et leur impact sur le régime alimentaire de Clarias Gariepinus (Burchell, 1822) de deux cours d'eau permanents de la région ouest du Burkina Faso
par Souleymane Sanogo
Université Polytechnique de Bobo Dioulasso (Burkina Faso) - Master Recherche en Analyse des Populations des Espèces Halieutiques 2010
Rivers «Kou» and «Wé» are two rivers in the west region of Burkina Faso. They contribute to the improvement of local economy.
In a comparative study of these two rivers, the inventory of macro-invertebrates population was realized during low water period, the beginning of rainy season and high water period.
On the «Kou» river 33 families of Insects, one family of Arachnid, one family of shellfish, two families of Annelid and five families of Mollusc have been identified, while on the «Wé» river 22 families of Insects, one family of Annelid, two family of Mollusc have been described. We notice on these two rivers a small quantity of EPT (Ephemeroptera-Plecoptera-Trichoptera) with 0.016% on the «Kou» river and 0.008% on the «Wé» river. The species belonging to these orders of Insects, very sensitive to pollution show by their abundance in a waterway a good ecological well being (Moisan & Pelletier, 2008).
Like observed in most waters bodies of the country, the two rivers are characterized by high presence of Insects (90.70% on the river «Kou» and 92.94% on the river «Wé»), and their benthic populations are dominated by Chironomidae (23.69% on the river «Kou» and 50.37% on the river «Wé»). The density of macro-invertebrates in the benthos of both rivers does not go beyond 500 individuals per square meter (m2) during the period of study.
This study has allowed us to analyse the diet of Clarias gariepinus (Burchell, 1822), in the river «Kou». This species of fish, despite its omnivorous diet, eats in majority Insects (occurrence index is 76.47%) and its weight increases during high benthic density period (low water period and high water period).
For the stability of the ecosystem of the two waterways, this study recommends their permanent survey in order to depict any ecological disturbance that will affect the whole region. This survey must include the education of the riverside population on the impact of domestic effluents on rivers waters quality.
Key words: macro-invertebrates - Chironomidae - Clarias gariepinus - domestic effluents
Les questions environnementales constituent aujourd'hui des défis majeurs pour la survie de l'humanité. Les récents bouleversements climatiques à travers le monde avec leurs corollaires de destructions des biens matériels et mê