Diversity, distribution and habitat requirements of aquatic insect communities in tropical mountain streams (South-eastern Guinea, West Africa)

Abstract – Considering that knowledge of the biodiversity of a region is the first step toward its conservation and given the paucity of studies on aquatic insects from the Simandou streams, the diversity of these communities was assessed. Aquatic insects were sampled with a hand-net (mesh size: 250 mm) on four occasions between March 2011 and September 2012 at 27 sites. Environmental variables were also recorded. Overall, 129 taxa belonging to 51 families and eight orders were recorded. Multivariate analyses gathered sites into three clusters in regard to aquatic insect composition. The rarefied taxonomic richness showed decreases in association with increasing levels of human impact. Cluster 1 that contained most disturbed sites displayed low taxonomic richness compared with the two others. The highest taxonomic richness was registered in cluster 2 that contained a mixture of upland and lowland sites; the latter remained minimally disturbed. These sites could be considered as reference sites in studies for assessing water quality. Generalised additive models calculated for the most frequent taxa showed that water temperature, dissolved oxygen, conductivity and pH were the incorporated explanatory variables. Therefore, further anthropogenic activities should preserve the surrounding forest in order to preserve the quality of Simandou streams and consequently aquatic biodiversity