Author(s): Gougloin Touamin Hugues Esmel, Dietoa Yehe Mathieu and Tah Leonard

Abstract: The macroinvertebrate inventory was carried out using samples taken at 6 stations distributed along the longitudinal profile of the Soubré lake and the downstream part of the Sassandra river. Sampling was carried out monthly from July 2019 to February 2020. A total of 20581 macroinvertebrate individuals belonging to 117 taxa (genera and species), 60 families, 17 orders and 6 classes were recorded. The macrofauna was largely dominated by molluscs, which accounted for 55.69% of the total richness of the macrofauna collected. Insects accounted for 40.26% of the total abundance of organisms collected. Annelids and crustaceans were the poorest groups in the population. Coleoptera was the most abundant order in terms of numbers of individuals, and Thiaridae was the most abundant family. Individuals from the Malacostracan faunal group represented 2.68% of the total population collected in the aquatic environments of the fluvio-lacustrine environment. This Malacostracan population was only sampled in the river environment, i.e. at the Tiémé (TIE, upstream from the dam), Pont (PON) and Karmel (KAR, downstream from the dam) stations. Arachnids (0.61%), bivalves (0.57%) and annelids (0.29%) appear to be present only anecdotally or even absent from other sites. In terms of the qualitative abundance of macroinvertebrates, there were 96 taxa belonging to the Insect class, representing 82.05% of the total diversity of the fluvio-lacustrine environment sampled. However, Gastropods had 12 taxa collected. The sampling stations located in the fluvial environment recorded high taxonomic diversity: Tiémé (73 taxa), Pont (68 taxa) and Karmel (62 taxa), in contrast to the sampling sites in the lacustrine environment, which recorded the lowest taxonomic richness. The Shannon diversity indices (H') vary spatially, with averages of H'=3.71 for the TIE site and H'=2.85 for the KPE station. Pollution-sensitive species such as Chironomidae, Thiaridae and Viviparidae were predominantly abundant. A taxonomic dissimilarity was observed between the lake and river stations. The fluvial-lacustrine zone has a greater diversity of aquatic macroinvertebrates than the Taabo lakes. Anthropogenic activities are the main factors influencing macroinvertebrate diversity in this ecosystem. This study opens up a scientific question on different aspects of research on the taxonomy, ecology and functional structure of aquatic invertebrates in this ecosystem for further study in this field.

DOI: 10.22271/fish.2023.v11.i4b.2832

Pages: 113-122  |  359 Views  189 Downloads

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