Ecological Status of Two Lakes in the Department of Bongouanou (Cote d’Ivoire)
KOUADIO Akissi Nathalie
*
Department of Science and Technology, Life and Earth Sciences Section, Higher Teacher Training College, Abidjan, Côte d’Ivoire.
GOGBE Zeré Marius
Department of Animal Biology, Faculty of Biological Sciences, Peleforo GON COULIBALY University, Korhogo, Côte d’Ivoire.
KOFFI Kouakou Barthélemy
Department of Science and Technology, Life and Earth Sciences Section, Higher Teacher Training College, Abidjan, Côte d’Ivoire.
GOORE BI Gnamien Willy Taunin
Research Unit of Hydrobiology and Water Ecotechnology, Laboratory of Natural environments and Biodiversity Conservation, Faculty of Biosciences, Félix Houphouët Boigny University, Abidjan, Côte d’Ivoire.
*Author to whom correspondence should be addressed.
Abstract
Lakes Kaby and Ehuikro are vital for the city of Bougouanou. However, the land around them has been transformed into areas for wastewater overflow, landfills site and agriculture. Therefore, this study aimed to characterize the ecological status of these lakes based on their fish fauna. Fish were sampled monthly from July 2017 to June 2018 using monofilament nets with mesh sizes of 15, 20, 25, 30, 40, and 60 mm. The captured fish were identified, measured, and weighed. The condition factor K and a graphical method of comparing abundance and biomass were used to determine the lakesʹ ecological status. Analysis of the ichthyological fauna showed that there was greater species richness in Ehuikro lake (12 species) than in Kaby lake (four species). These species were distributed among nine genera, six families and three orders. Kaby and Ehuikro lakes were dominated by Oreochromis niloticus and Hemichromis fasciatus, respectively. The length-weight relationship revealed that Clarias anguillaris, Parachanna obscura and O. niloticus exhibited negative allometry in Lake Kaby. For these species, growth is isometric in Ehuikro lake. The condition factor was greater than 1 in both lakes. The highest condition factor values were obtained in Cichlidae. The ecological stress index showed that the abundance curve was above the biomass curve in Kaby and Ehuikro lakes, with negative values. By the end of the study, it was revealed that ecological conditions were even better in Ehuikro lake than in Kaby lake. The fish exhibited a wide range of ecological plasticity in adapting to environmental disturbances. Regarding, the ecological state of the lakes, the ecological stress index showed that both reservoirs were polluted.
Keywords: Fish, anthropogenic activities, ecological state, lakes, Bongouanou