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Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/2909

Title: Comparative Study of Macroinvertebrates and Diatoms as Bioindicators of River Water Quality in Addis Ababa
Authors: Taffere, Addis Wassie
Advisors: Prof. Dr. Ludwig Triest (Vrije Universiteit Brussel)
Abebe Beyene (Vrije Universiteit Brussel)
Keywords: indices
monitoring
water quality
bioindicator
diatoms
macroinvertebrate
Copyright: Jul-2008
Date Added: 10-May-2012
Publisher: AAU
Abstract: A crucial element in planning water quality assessment, management and conservation programme of a river is the selection of the biological indicators used to appraise biodiversity and environmental conditions. The present study, therefore, aimed at comparing macroinvertebrates and diatoms as bioindicators of river water quality in Addis Ababa. A total of 16 sampling stations were selected along the course of Kebena River and Little and Big Akaki Rivers for qualitative evaluation of physical habitats and collection of samples used for the determination of the taxonomic composition and abundance of macroinvertebrates and diatoms. Riffle sites were chosen for sampling to make the comparison among sites easier. Standard methods of sampling and analysis of samples were employed throughout the study period. Biotic indices and multivariate analytical methods, particularly dissimilarity index, clustering and indirect ordinations were used for the analysis of the results. Macroinvertebrates diversity was extremely poor precluding comparison among sampling stations. The highest and lowest macroinvertebrates taxa richness was 5 and 0 respectively. Surprisingly, only two macroinvertebrates taxa were found at the upstream site of Kebena River, which had the least anthropogenic disturbance but with the least physical habitat quality (40.6 %). But, the highest diatom tax richness (30 taxa) was observed at this site followed by 17 taxa at the upstream of both Little Akaki and Big Akaki Rivers. The lowest diatom taxa richness (4 taxa) was observed near the discharge point of Awash Tannery, where other industries are also concentrated. Community loss index for diatom data was higher at sampling sites receiving industrial effluent. All diatom biotic indices were indicative of responses to load of pollution though it was not possible to select the index that could discriminate impacted sites from reference site clearly with such cross-sectional study. Generally, the study depicted that the rivers in Addis Ababa are highly affected by physical habitat degradation and pollution due to point and non-point sources. Based on biotic indices and multivariate analysis results, diatoms are found to be better than macroinvertebrates in indicating sources and degree of pollution as well as in discriminating reference site from impacted sites of the study area. Hence, studies that consider seasonal variations and all the factors that determine diatoms composition are recommended in order to develop a refined diatom-based river water quality monitoring tool for the rivers in Addis Ababa and other parts of the country. Furthermore, responsible authorities should take urgent ameliorative measures to improve water quality of the rivers in the city.
URI: http://hdl.handle.net/123456789/2909
Appears in:Thesis - Environmental Engineering

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