Water Quality Assessment of Eastern shore of Lake Hawassa Using Physico-Chemical Parameters and Benthic Macro-invertebrates
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Date
2011-06
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Addis Ababa University
Abstract
At present, the use of benthic macro-invertebrates together with physico-chemical parameters has become a reliable and timeliness method for water quality assessment. The main aim of this study was determining water quality of Hawassa Lake from eastern shore using biological and physico-chemical parameters. The study was carried out in Hawassa Lake, Ethiopia from September, 2010 to March, 2011. During the study, a total of 0.56m2 area sampled from each of six sites along eastern shore of the lake using Ekman grab and D-net. Totals of 1872 benthic macro-invertebrates belonging to 38 taxa were collected. The study showed that most of the physico-chemical results were significantly correlated with benthic metrics. The high occurrence of Chironomidae at S6 showed strong positive correlation with high concentration of NO3- (r= 0.960, P< 0.05). The low occurrence of Gastropods in S1 was negatively correlated with electrical conductivity, TDS and PO43- (r= -0.831, P< 0.05; r= -0.877, P< 0.05 and r= -0.86, P< 0.05), respectively. Hilsenhoff biotic index categorized most of the sites under fairly poor water quality but S1 was categorized under good water quality in contrast to results of physico-chemical parameters. The reference site S4 and S3 contain large number of macro-invertebrates with moderate tolerance and pollution sensitive groups. The result of the study indicates that benthic metrics designed for rivers and stream assessment also work for discriminating impacted sites in lakes.
Key words/phrases: Benthic macro-invertebrates; Bioassessment; Hilsenhoff biotic index; Lake Hawassa; Physico-chemical parameters; Water quality.
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Keywords
Benthic macro-invertebrates; Bioassessment; Hilsenhoff biotic index; Lake Hawassa; Physico-chemical parameters; Water quality