Assessing the Ecological Health of a River in North-West Nigeria using Macroinvertebrates Structural Assemblage and Environmental Factors

The ecological health of River Kafin Hausa was assessed in three well marked out stations for a period of four (4) months, spanning from January to April, 2018. Water samples were collected at each sampling site and analysed according to approved standard. The habitat quality evaluation index (QHEI) was used to assess the habitat quality of the riparian zone of the river. A modified kick net with 4.4 square feet (1.36m2) squared frame net was used to sample macroinvertebrates. Water quality variables were not significantly different among the months and stations sampled. Electrical conductivity, pH and TDS were higher in station 2 with mean value of 327+34µS/cm, 11 and 200.05+20.95mg/l respectively. Station 1 had the highest QHEI value of 49%. A total of 11 classes/orders, 23 families and 24 taxa of macroinvertebrates were recorded. Gastropoda was the most represented order of macroinvertebrates. Diversity indices showed significant differences (p<0.05) in the means of Taxa, Evenness and Margalef Index in station 2. The canonical correspondence analysis revealed a very weak relationship between the species composition and abundance with the selected environmental variables in the river. Flow velocity was found to influence the composition of Corbiculidae, Hydrobiidae and Potadoma sp. Chironomus sp., Viviparidae and Gyrinus sp. were associated with station 2. Bray-curtis similarity clearly showed no pattern of clustering between the months and stations. The study shows that the river has been subjected to disturbance in the river channels and catchments which was hinged on incessant anthropogenic activities.