Effects of anthropogenic activities on the diversity and distribution of macro-invertebrates in Katanga stream

Abstract

Katanga stream flows through Katanga slum situated between Makerere University and Mulago hospital. The stream receives untreated waste water from various anthropogenic activities such as motor vehicle washing, motor vehicle repair centers, and laundry activities, among others which affect the water quality, the diversity and distribution of macro-invertebrates. This study was undertaken to examine the effects of anthropogenic activities on diversity and distribution of macro-invertebrates in the Katanga stream. Water and macro-invertebrate samples were taken from selected stations along Katanga stream for a period of 6 weeks. Water samples were analyzed for pH, NH3-N, TP, Temperature, D.O, and TDS. These were compared with the standards set by NEMA for waste water. All the physico-chemical parameters except temperature at various stations varied significantly (pH (p < 0.05, F=11.84), NH3-N (p < 0.05, F=286.74), TP (p < 0.05, F=137.1), Temperature (p > 0.05, F=2.64), D.O (p > 0.05, F=106.80), TDS (p > 0.05, F=50.29)). The diversity and distribution of macro-invertebrates was heterogeneous. The nature of the substratum, riparian vegetation and effluent discharge affect adult population dynamics and determine habitat structure and quality, thus they were important factors in determining the composition and diversity of macro-invertebrates. 374 organisms were identified and analyzed belonging to 4 orders and 8 families. Order Diptera made up 45% of total abundance followed by Tubificida with 32.6%, Basommatrophora with 9.6% and Mesogastropoda with 12.8%. Results revealed that anthropogenic activities had detrimental effects on macro-invertebrates diversity and distribution. Therefore, strict measures should be exercised by the local authority to ensure that raw effluents discharged into streams are treated