ICHTHYOLOGIC DIVERSITY OF BANDAMA RIVER BASIN (CÔTE D’IVOIRE): AN UPDATE AND ENVIRONMENTAL INFLUENCES ON FISH DISTRIBUTION

Abstract

The inventory and distribution of fish assemblages of Bandama River were studied from October 2008 to September 2009. Fish samples were collected in three areas (upper, middle and lower catchment) using a back pack electrofisher and two batteries of gill-nets with mesh sizes between 8 and 80 mm. A total of 64 sites were visited and 83 fish species belonging to 11 orders, 30 families and 51 genera were identified. We counted 13 marine and/or brackish-water species and 70 freshwater species. Among them, two introduced species (Heterotis niloticus and Oreochromis niloticus) and one hybrid form (Tilapia zillii x T. guineensis) were found. Characiformes order, mainly represented by Alestidae family and Brycinus longipinnis species, are the most abundant. Studies comparing biodiversity of families used species richness and abundance, showed that families of Cichlidae and Cyprinidae (16% of species each), Mormyridae (11% of species) and Alestidae (10% of species) werethe most abundant. The influence of environmental parameters such us width, dissolved oxygen, turbidity, depth, canopy closure, mixed sand-gravel and aquatic plants on the distribution of fish population has been highlighted by a redundancy analysis (RDA) coupled with Monte Carlo test 499 permutations.