Ecological studies of benthic macro_ invertebrates from a sediment along gradient in the Awash River, Ethiopia
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Date
2017-01
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Addis Ababa University
Abstract
Macro_ invertebrates are good indicators of human land use impacts because they are
sensitive to habitat alterations. The present study aimed at assessing the ecological impacts of
sediment loading on macro-invertebrates with the view to develop sediment sensitive
invertebrate index (PSI) along the gradient of Awash River, Ethiopia. Three sampling sites
were selected along the gradient of Awash River for evaluation of physicochemical
parameters, soil particle size, organic matter and determination of the richness and diversity
of macro-invertebrates. Macro_ invertebrates were collected using standard dip net based on
Rapid Bio Assessment Protocols for use in streams and wadeable rivers from the same kinds
of microhabitats (pools and vegetated areas)and identified to the family level. Alongside, on
site of measurement of Physico chemical parameters (To,DO,pH and Conductivity ) were
taken. The results indicated that concentrations of dissolved oxygen, temperature, pH,
conductivity, Nitrite and Nitrate showed significant difference among samplingsites
(ANOVA),(P< 0.05). The percentage abundance of families of macro_ invertebrates was
determined from all sites. Total of 19 families comprising 7,094 individuals were identified
from all the sites. The sediment sensitivity result indicated that site one (S1)was moderately
sedimented and had the highest family richness, while site three (S3) was heavily sedimented
with the least family richness. Macro_ invertebrate which indicated moderately sedimented
sites are Baetidae and Lepidostomatidae whereas for heavily sedimated site Hydrophilidae
and Lymnaeidae were dominant. The study indicated significant effect of different levels of
sedimentation on macro-invertebrate community structure.As the sediment emanated from the
degraded Awash catchment, there is need toprevent and control the ever-increasing
degradation of the water quality of this ecologically and economically important river.
Key words: Awash River, Bio indicators, Macro _invertebrate, PSI; RDA, Sedimentation.
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Keywords
Awash River, Bio Indicators, Macro _Invertebrate, PSI, RDA, Sedimentation