Laboratoire des Milieux Naturels et Conservation de la Biodiversité, UFR Biosciences, Université Félix-Houphouët-Boigny, 22 BP 582 Abidjan, Côte d’Ivoire
The contribution of remote sensing to controlling the proliferation of invasive aquatic plants is of paramount importance, as it makes it possible to better monitor the spatio-temporal evolution of these plants’ occupation of water bodies. The surface of the Comoé River estuary has always been occupied by Invasive Aquatic Plants (IAPs). This study was carried out with a view to listing all the aquatic plant species colonising the surface of the estuarine water body and analysing the dynamics of their proliferation. To achieve this, the study’s first stage consisted of carrying out an itinerant inventory along transects installed on the water body to record all the species encountered. In the second stage, the colonisation dynamics of the estuary were analysed using four Landsat (TM) 1986, 1989, Landsat 7 (ETM+) 2004 and Landsat 8 (OLI) 2022 satellite images. The floristic inventory identified 8 species divided into 8 genera and 8 distinct families at the surface of the estuary water body. Analysis of land use dynamics from 1986 to 2022 shows a variation in the annual rate of expansion of IAPs on the surface of the estuary water body. The recent period from 2004 to 2022 is characterised by a considerable rate of expansion of around 1240.2%. The results of this study could constitute a reliable scientific database for the implementation of a policy to control the proliferation of these IAPs at the surface of the water body of the Comoé River estuary.
The aim of this study was to determine the diversity and structure of aquatic macroinvertebrates in the middle course of the Comoé River. Sampling of macroinvertebrates was carried out at four stations in this course. A total of 3921 individuals of aquatic macroinvertebrates were identified in this part of the river. These macroinvertebrates are divided into 137 taxa, 72 families, 17 orders and 6 classes. Insects with 64% numerically dominate this population of aquatic invertebrates. They are followed by gastropods (21%). Ephemeroptera (27%), Mesogastropoda (21%) and Coleoptera (13%) are the most abundant orders. The most diverse orders are Coleoptera (27 taxa) followed by Ephemeroptera (19 taxa). The Dytiscidae (8 taxa) constitute the most diversified family in this part of the river. According to the number of individuals per species, Melanoides tuberculata (8%) dominates in the middle course. In the middle course, the Shannon-Weaver index varies from 2.85 to 3.56 and the fairness from 0.83 to 0.95. The abundance coupled with the various indices of diversity studied reveal that the waters of the stations of the middle course are well populated in aquatic macroinvertebrates and well diversified.