Identifying and Classifying Sites and Macroinvertebrate Taxa into Pollution Categories in an Afrotropic Riverine System: A Multivariate Approach

Abstract

Measuring the level of degradation in riverine systems is paramount to assess their current health status. In this study we categorized sites and macroinvertebrate taxa into pollution and biological categories, respectively. Sites categorization was done for four sites, while 12 taxa were biologically categorized in River Ringim, North-western Nigeria. The principal component analysis we constructed showed that physico-chemical variables such as total dissolved solids, conductivity and pH were positively associated with site 2 while sites 3 and 4 were negatively associated with water temperature, air temperature and flow velocity. Further analysis based on the extracted coordinate scores of the four sites, revealed that sites 2 and 4 were critically polluted while sites 1 and 3 were slightly and heavily polluted, respectively. The result of the canonical correspondence analysis revealed  macroinvertebrate taxa such as Leutridae and Hydromitridae were positively associated with conductivity, flow velocity, water depth, water temperature, air temperature, DO and pH, confirming their level of tolerance to pollution. Of the 12 taxa categorized, nine were highly vulnerable portraying their level of vulnerability in the sites studied. Our study provides baseline information on the current state of River Ringim, and we recommend more sampling efforts to confirm our present findings.   &nbsp