Benthic Macroinvertebrates Diversity in the Tiemba River, North-West of Côte d’Ivoire

This study was carried to determine the diversity and structure of macroinvertebrates in the Tiemba river in north-west Côte d’Ivoire. Sampling of these macroinvertebrates was carried out at four different stations in the river using a Van Veen bucket and a haul net over an area of 1 m² (2 m * 0.5 m). The structure of benthic species was then studied using Shannon and Piélou indexes. Finally, a Canonical Correspondence Analysis (CCA) was carried to compare the relationship between the distribution of macroinvertebrate species and physicochemical variables. The results showed that a 253 macroinvertebrate species, divided into 04 classes, 09 orders and 20 families, were identified in the Tiemba river. This macrofauna is made up of 78% arthropods, 16% molluscs and 6% worms. The insect class was the best represented, with several orders including Hemiptera, Coleoptera, Diptera, Odonata and Hymenoptera. The most dominant orders in this river are Hemiptera, Coleoptera and Diptera, which are pollutant-resistant organisms, reflecting moderately polluted water. Analysis of the diversity indexes revealed that the macroinvertebrate groups in the Tiemba river are diverse and well organised. The distribution of macroinvertebrates was strongly influenced by temperature, conductivity, pH, nitrite, dissolved oxygen and depth. These results provide the foundations to all biomonitor action for the ecological quality of that river.

Keywords: Macoinvertebrates, Tiemba River, Diversity, Pollutants, Distribution.