Biodiversity and ecology of epilithic diatoms in the Agnéby River,Ivory Coast

The ecology and taxonomy of the epilithic diatom flora of the Agnéby River, Ivory Coast were studied in 2012. Ten sites were investigated and diatoms were sampled on glass slides immersed for a period of 30 days during the wet and dry seasons. Physico-chemical parameters were measured at each site while sampling diatoms. Five taxa were largely dominant: Planothidium comperei CE Wetzel, N’Guessan and Tison-Rosebery, Eolimna minima (Grunow) Lange-Bertalot, Planothidium piaficum (JR Carter and Denny) CE Wetzel and Ector, Cocconeis schroederi Foged and Cocconeis scutellum var. parva (Grunow in Van Heurck) Cleve. Electrical conductivity, temperature, dissolved oxygen, nitrite and phosphorus were found to influence the distribution of taxa.     

Feeding habits of the mochokid Synodontis punctifer Daget, 1964, in the Bandama River,Côte d'Ivoire

The feeding habits of Synodontis punctifer were investigated in the basin of the Bandama River. Fish specimens were collected using gill nets in the rainy season (May–July 2009) and in the dry season (November 2008 to March 2009 and August 2009). In this article, the importance of the different prey types was assessed using the corrected occurrence and weight percentage. These values were used to calculate the index of preponderance for each taxonomic category. One hundred and ten specimens of S. punctifer were examined, nine stomachs were found empty (8.18%). A total of 39 different prey species belonging to seven major groups Insects, Crustacea, Rotifera, Molluscs, Other invertebrates, Other organisms and Macrophytes were identified in the stomach contents. The results showed that Macrophytes were the primary food item and Insects the secondary prey item. Other preys were recorded occasionally. At the rainy season, the main foods of S. punctifer were Macrophytes and during the dry season this species ate Insects and Macrophytes. The food composition varied between localities. In the riverine localities, specimen fed on 38 prey types. Twenty‐seven prey categories were consumed in the lacustrine. In terms of diet overlap, Schoener coefficient values were above the 0.6 limit (α = 0.99), indicating some high overlap.