The diversity and distribution of macrobenthic invertebrates in Kiwunya Stream

Abstract

This study was carried out with a general objective of establishing the diversity and distribution of macrobenthic invertebrates in Kiwunya Stream located in Kampala District which has constantly been subjected to higher levels of pollution mainly due to the anthropogenic activities carried out by the communities living along this stream. This work involved measurements of the different physico-chemical water parameters like temperature, pH, flow velocity, dissolved oxygen, water depth, phosphates and nitrate levels at three sites, that is upstream, midstream and downstream. These parameters were later related to the distribution and diversity of the macrobenthic invertebrates found at the different sites of sampling. The study showed that water temperatures increased from upstream to downstream, the pH range was 7.0-75, the stream was shallow having a depth that increased on average from 6.8cm upstream,7.6 cm midstream and 18.8 cm downstream. The dissolved oxygen levels were highest upstream and lowest downstream, the flow velocity was highest upstream (0.39m/s), midstream (0.24m/s) and lowest downstream (0.18m/s). Phosphate and nitrate levels were highest upstream and these decreased as one proceeded to the downstream. The study revealed three phyla of macrobenthic invertebrates present in the different sampled sites of the stream and these include Mollusca, Annelida and Arthropoda with the midstream having the highest Shannon wiener diversity index(H`) of 7.34 and the downstream having the lowest diversity(H`) of 4.69. However, the downstream had the highest number of individuals, followed by the midstream and then the upstream with the lowest number of individuals.