Structural organization of the macroinvertebrates communities of the Alibori River during the rainy season (Northern Benin)

Abstract

The impact of cotton activities on the structuring of the macroinvertebrates communities of the Alibori River was evaluated. Samplings were carried out at 15 sites from June to September 2015 during the rainy season. The benthic macrofauna inventory revealed 53 taxa of aquatic invertebrates belonging to 33 families, 13 orders and 7 classes. Insects composed 70% of species identified with 6 orders, 23 families and 40 species. Molluscs comprised 12% of species identified. Analysis of the structure with the Self-Organizing Map (SOM) revealed a zonal distribution upstream-downstream which indicates that the various sampling sites had in common a great part of benthic fauna and that their differences are a limited number of taxa which were specific to each sampling sites. The zonal distribution of organisms reveals an anthropogenic disturbance along the River. The redundancy analysis carried out between the physico-chemical variables and the main taxa, showed that nitrates, phosphates, conductivity, Total Dissolved Solids (TDS) were the important parameters which influenced the distribution of macroinvertebrates.