Distribution of macro invertebrates along Bulyera stream, Lubigi catchment

Abstract

Bulyera stream, located in northeastern part of Kampala, the capital city of Uganda, is under the significant anthropogenic influence, which affects its physical and chemical characteristics and subsequently altering the ecological integrity. This study investigated the relationship between macro-invertebrate distribution with the physical and chemical characteristics of the stream. Water and sediment samples were collected from six points of the stream to determine Dissolved oxygen, Biological Oxygen Demand and macro-invertebrate diversity and abundance. In addition, flowrate, depth, width, and temperature were determined in-situ. The diversity of macro-invertebrates decreased downstream, with Chironomidae, and Naididae dominating the upper and lower reaches respectively. Clay and sandy sediments respectively had a positively and negatively significant effect on both family Thiaridae and Physidae. The type of sediment had a negatively significant effect on Naididae, Chironomidae and Nepidae. DO had a positively significant influence on the number of Chironomidae, Culicidae and Nepidae. On the other hand, depth and BOD had no significant effect on macro-invertebrates. Generally, with the exception of depth and BOD, this study revealed that the physical and chemical characteristics of the stream affect the distribution of macro-invertebrates. The study recommends restoration of the stream to improve the stream health. Authorities should restrict the public from building just next to the stream banks, or from planting crops, by constructing a perimeter fence along the stream.