Effects of anthropogenic activities on the diversity of macroinvertebrates in the Kasokwa stream.
Abstract
Kasokwa stream is threatened by anthropogenic activities such as wastes from farm plantations, washing bays and domestic wastes. The study was carried out with a general objective of determining the effect of anthropogenic activities on the diversity and distribution of macroinvertebrates in Kasokwa stream in Masindi District with a specific objective of determining the effect of human activities on water quality in the stream. The different water quality parameters that were measured included temperature, pH and Dissolved Oxygen. In addition to that, the effect of human activities on water quality and the relationship between water quality and distribution of macro invertebrates at the three selected sites of Kasokwa stream were determined. The results indicated that in the wet season, there was a significant difference between the mean pH upstream and the mean pH downstream (t=9.192, df=2 p=0.0116) while with other parameters, there was no significant difference between the upstream and the downstream. In the dry season, there was a significant difference between the mean DO, mean pH and mean temperature upstream with the mean DO, mean pH and mean temperature downstream respectively. Additionally, the diversity of the macroinvertebrates was varying along the stream depending on the water quality and the nature of the catchment areas. The study also showed that water temperatures increased from upstream to downstream with the highest recorded temperature being 28.3 0C and the lowest temperature being 24.7 0C, the pH range was 7.7-6.3. The common macroinvertebrates that were found in the stream are Chironomidae, Hydrophillida, Libelluloidal, Coenomidae, Gyrinidae, Physidae, Hirundidae, Simullidae, Chaoberidae and Plaonorbeae. The highest number of the macro invertebrates was seen in the Chironomidae family and followed by Libelluloidal family. Generally, in both the wet and dry seasons, the Katorogo site had the highest diversity of macro invertebrates while the Zebra site had the lowest diversity of macro invertebrates. That is to say, that in the wet season, the Shannon diversity index for Katorogo site was 1.43 while that of zebra site was 0.951. On the other hand, in the dry season, the Shannon diversity index for Katorogo site was 1.63 while that of Zebra site was 1.28. This pattern suggests that the middle section of the stream (Katorogo) may be less affected by anthropogenic activities compared to the upper (Zebra) and lower (Kakeka) sections.