Effect of anthropogenic activities on the ecosystem health of Nyangahya Stream using macroinvertebrates as bioindicators

Abstract

A study was carried out with a general objective of assessing the water quality using a combination of benthic macroinvertebrate as bio-indicators and selected physico-chemical parameters in Nyangahya stream located in Masindi District. The Stream 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, near catchment activities and macroinvertebrates 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 7.8-6.6. The dissolved oxygen levels were highest upstream and lowest downstream, the flow velocity was highest upstream, midstream and lowest downstream (Table 1). The near catchment activities of the stream also decreased with the increasing in settlements around it. The study revealed three phyla of macrobenthic invertebrates present in the different sampled sites of the stream and these include Arthropoda, Mollusca and Annelida with the upstream having the highest Shannon wiener diversity index and the downstream having the lowest diversity (Figure 2). However, the upstream had the highest number of individuals, followed by the downstream and then the midstream with the lowest number of individuals (Figure 3). Generally, the current study revealed that unregulated human activities and development projects in the near catchment significantly affects stream health. The study recommends enforcing effective environmental policies for instance enforcing minimal distance from the stream channel to maintain vegetation development.