Studies on Benthic Macroinvertebrates of Lake Hayq, Ethiopia
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Date
2010-01
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Addis Ababa University
Abstract
Studies on the benthos of Lake Hayq were carried out at three stations from November, 2008 to
April, 2009. Bottom samples were collected by using an Ekman grab (225cm2). Determination
of total organic matter of littoral and profoundal samples was done using an oven and a muffle
furnace. Communities of benthic fauna were reported from the lake in relation to the type of
bottom substrates and aquatic macrophytes. The benthic macroinvertebrates of the bottom near
to the emergent and submerged vegetation and the vegetation-free region of the lake were
identified and their distribution in the lake was recorded in relation to the total organic matter
and texture of the bottom sediment. Mollusks were found to be the most numerous of all
benthic communities (mean number 52306individual/m-2). The Dipetra larvae were next with
Chironomidae accounting the highest number. Bottom samples taken from near the vegetated
regions of the lake were found to have a silt texture and the vegetation-free zone was sandy in
texture. The result shows that near vegetated regions of the lake bottom had higher organic
matter content than the bottom of the non-vegetated region. The sub-littoral region had highest
richness (d = 2.13) while, the highest diversity (H = 1.8), evenness (J (e) = 0.209) and
community density (43673.77 ind|m2) were in the littoral region. It was observed that most
benthic taxa of Lake Hayq were concentrated in the littoral and sub littoral region in
association with macrophytes. The littoral and sub littoral zone can therefore be considered as a
site of good habitat and breeding ground for macroinvertebrates. Since there is considerable
dependence of many commercial fish species on the invertebrate fauna as food resource, there
is need to investigate further the biology and ecology of the benthic organisms and weed beds.
It is also important that lake management should maintain the integrity and health of the
macrophytes of the lake.
Key words: Benthic macroinvertebrate, Ekman grab, Littoral, Macrophytes, Profoundal,
Shannon diversity index, Sub-littoral
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Keywords
Benthic macroinvertebrate, Ekman grab, Littoral, Macrophytes, Profoundal, Shannon diversity index, Sub-littoral