Ecological Assessment of Lake Hora, Ethiopia, Using Benthic and Weed-bed Fauna
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Date
2010-07
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Addis Ababa University
Abstract
The purpose of this study was ecological assessment of Lake Hora using
benthic and weed-bed faunas. Samples of benthic and weed-bed were
collected monthly from September 2009 to March 2010 at 3 sampling stations
(A, B and C). Stations A and B were faced with human disturbance and station
C was free from human interaction. Station A is in front of Ras Hotel, station B
is place of Irecha and station C was to the south crater of the lake. Bottom
samples were taken to determine sediment texture and total organic matter of
the lake. The result obtained showed that the weed-bed had sandy loam texture
and the profundal had loamy soil. Generally, total organic matter content of
station C was lower than A and B (with an average of 8.3, 20.8 and 18.0,
respectively). The benthic and weed-bed fauna of Lake Hora included a total of
6958 belonging to 27 taxa with principally Copepod (2812), Chironomidae
(1460) and Ecdyonuridae (735). A high number of organisms were observed
mainly at stations B and A (3198 and 2342, respectively) and lower numbers
were observed at station C (1419). As compared to stations A and B, station C
was cooler in its water temperature but its dissolved oxygen content was not
higher. Correlation between macroinvertebrates and temperature and total
organic matter was insignificant (P>0.01). The correlation result verified that
oxygen showed strong relation to benthic and weed bed fauna distribution and
abundance. There were high number of individuals, taxa diversity, evenness
and great number of rare taxa of benthic and weed-bed fauna at stations of A
and B, but these stations were human influenced areas and affected by the
community around the lake area for different reasons (for example washing
clothes, boat parking and others). The FBI index for all the sampling stations
was 7.55, according to Hilsenhoff Family Biotic Index this value is between 7.26
and 10.00 and indicating likely severe organic pollution and very poor water
quality throughout the study lake
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Biology