Stressor Based Water Quality Assessment Using Benthic Macroinvertebrates as Bioindicators in Streams and Rivers Around Sebeta, Ethiopia
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Date
2017-07
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Addis Ababa University
Abstract
The increasing impact of human activities on the freshwater bodies of Ethiopia calls for efficient and cost
effective method for water quality and ecological health assessment. Benthic macroinvertebrates are
important group of aquatic invertebrates to show the level of degradation of aquatic ecosystems and in
this study they were used to assess the impact of different stressors originating from industries (tannery,
alcohol, brewery and textile factories) and agricultural activities on streams and rivers around Sebeta. A
total of 27 benthic macroinvertebrates taxa (20 families, 1 genus and 6 species) were collected from nine
sampling sites in four streams, representing different anthropogenic activates. From these, Family
Planariidae, Caenidae, Baetidea, Hydropsychidae, Gyrinidae, Dystiscidae, Hydrophilidae, Naucoridae and
Corixidae were distributed mostly from reference site to minimally impacted upstream sampling sites and
considered as indicators of minimally impacted streams and rivers. Family Syrphidae and Thiaridae were
dominant in streams with high turbidity and can be an indicator of turbid streams and rivers. Family
Chironomidae, Lymnaeidae and Oligochaeta were dominant in highly polluted sites (brewery and textile
effluent receiving sites) and can be indicator of highly polluted streams and rivers. From lower taxonomic
level of Family Chironomidae, Chironomus alluaudi and Chironomus imicola were dominant in highly
polluted sites (brewery and textile effluent receiving sites), and considered as an indicator of highly
polluted streams and rivers. The distribution of Polypedilum wittei, Polypedilum bipustulatem and
Dicrotendipus septemmaculatus were high in moderately impacted sites and considered as indicators of
moderately polluted streams and rivers. The genus Conchapelopia and Chironomus cliptres were mostly
distributed in reference and less impacted upstream sampling sites and can be indicators of good water
quality. Metrics composed of sensitive group of taxa (No. of Ephemeroptera, No. CET and %ET) were
able to differentiate reference sites, agricultural impacted sites and some instream activities
(washing/bathing and cattle watering site). Metrics composed of tolerant taxa like number of Oligochaeta
individual and %Diptera individual distinguish highly impacting industrial stressors (tannery, beer, textile
and alcohol). Margalefs index may detect toxic effect of industrial wastes in addition to organic pollution.
Total number of ind/m2, number of Taxa (Family), ETHbios, and FBI were able to segregate stressors
originated from different sources (agriculture, washing/bathing and industries). Freshwater bodies are
highly deteriorated and research should focus on waste water treatment technologies and adequate waste
treatment structures must be put in place at the industries and factories located along streams and rivers
around Sebeta.
Key words: Bioindicator, Benthic macroinvertebrate, Chironomidae, Sebeta, Stressor
Description
Keywords
Bioindicator, Benthic macroinvertebrate, Chironomidae, Sebeta, Stressor