Relationship Between Water Quality Indicators And Benthic Macroinvertebrate Assemblages In The Kuywa River, Kenya

Abstract

The Kuywa River watershed has undergone riparian vegetation planting since 2006 in order to improve the river health. The planted riparian buffer zone vegetation was to improve channel stability, promote biodiversity, and improve water quality. Studies undertaken elsewhere have investigated how environmental factors affect ecosystem processes and functionalities but fail to show how water quality indicators influence the structure of the benthic macroinvertebrates. However, this study investigated the relationship between water quality indicators and benthic macroinvertebrate assemblages in the Kuywa River. Nine sites were assessed of different riparian vegetation zone conditions, consisting riparian assessment, benthic macroinvertebrate collection, and water quality sample collections for analysis for different parameters. PCA was performed on physico-chemical indicators and then BIO-ENV BEST to determine any significant relationship between physico-chemical and benthic macroinvertebrates. ANOSIM was employed to test the hypothesis for variations between the sampling sites in terms of physico-chemical parameters and riparian vegetation cover. Spearman rank correlation indicated that some water quality indicators area related to benthic macroinvertebrate assemblages while others did not respond. Elassoneuria(r=0.78), Ephemerella (r=0.75), Synclita (r=0.79), Macrobdella (r=0.90) and Actnonaias (r=0.91) were highly correlated with dissolved oxygen (ρ<0.05). Hexatoma was highly correlated with percentage canopy cover (r=0.83, ρ<0.01) at the nine sampling sites. However, Actnonaias was also highly correlated with DO (r=0 …