Biodiversity of benthic macroinvertebrates in some coastal rivers of the South Cameroon region

Abstract

Benthic macro-invertebrates are organisms that are visible to the naked eye and live on the bottom of rivers and streams or only move a short distance away during most of their lives. In order to determine the taxonomic composition of benthic macro-invertebrates in the waters of coastal streams in forest areas, a study was conducted in Kribi in the Ocean Department from February to September 2022. The physicochemical and biological analyses were carried out according to traditional methods at the hydrobiology and environment laboratory of the Faculty of Sciences of the University of Yaoundé I. Sampling of benthic macro-invertebrates was carried out using a multi-habitat approach and a square-shaped net with a 400 µm mesh opening. The collected organisms were fixed with 10% formalin in glass pillboxes. In the laboratory, the specimens were washed with running water and then preserved in 70° alcohol before identification and counting. The results of the physicochemical analyses of the waters revealed that they are in the range of moderate quality waters. During this study, 4636 individuals were collected belonging to 2 phyla (Molluscs and Arthropods), 3 classes, 19 orders, 54 families and 110 genera. The Mollusca phylum corresponds to 2468 individuals or 53.23% of relative abundance and the Arthropoda phylum to 2168 individuals or 46.76% of relative abundance. The class of Gastropods predominates with 2468 individuals, i.e. 53.23% of relative abundance, followed by Insects with 1174 individuals, i.e. 25.32% of relative abundance, then Crustaceans with 994 individuals, i.e. 21.44% of relative abundance. From the global point of view of the biological data recorded during this study, it was noted that , there is a dominance of the Gastropod class.