Macroinvertebrate community structure and spatial distribution in the lower section of Kossou Lake (Côte d’Ivoire)

Ecological monitoring was carried out in Kossou Lake, one of largest and most important in Côte d’Ivoire, in particular in its low section more vulnerable because functioning as a receptacle of all anthropogenic pollutions. In this perspective, by means of four sampling points defining a linear transect was explored eight times from November 2017 to September 2018, we investigated the macroinvertebrate community so as to characterize the environmental factor governing their spatial distribution. This aquatic fauna was sampled with both hand-net (mesh size: 250 mm) and Van Venn grab. The environmental variables were also recorded. A total of 4500 organisms belonging to 135 taxa, 71 families, 12 orders and seven classes were collected. The indices diversity declined progressively from littoral to sublittoral zones. Numerically, the samples were dominated by Chironomidae (Insects) and Thiaridae (Gastropods). Multivariate analysis provided evidence firstly that indicator taxa were only identified in the littoral zone through the indicator value (IndVal) index. After all that, the generalized additive model based on constant taxa shows that the environmental parameters such as depth, pH, temperature, conductivity and dissolved oxygen have contributed to the occurrence of these taxa. Apparently, some species would appear to have acquired some coping methods against of the numerous anthropogenic pressures. Therefore, it would be necessary to control the occupation style of the watershed to preserve the littoral zones of this lake, which is an asset to the expansion of aquatic biodiversity.