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Macroinvertebrate‐based bioassessment of rivers in Addis Ababa, Ethiopia
Author(s) -
Desalegne Solomon A.
Publication year - 2018
Publication title -
african journal of ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.499
H-Index - 54
eISSN - 1365-2028
pISSN - 0141-6707
DOI - 10.1111/aje.12444
Subject(s) - ordination , invertebrate , taxon , ecology , geography , abundance (ecology) , generalist and specialist species , environmental science , pollution , sass , hydrology (agriculture) , biology , habitat , geology , computer science , programming language , geotechnical engineering
Chemical‐based studies have shown pollution of rivers in Addis Ababa, Ethiopia. However, as bioassessment is not a component of the river assessment and monitoring programmes, information on the ecological status of the rivers is limited. The study assessed the ecological status of the Little and Greater Akaki Rivers using macroinvertebrates. Macroinvertebrates were collected from twelve sites twice in the dry and wet seasons. There was abundance of few tolerant, collector‐gatherer taxa with a loss of most sensitive taxa that used to be part of the river systems. Macroinvertebrate communities from upper and lower reaches showed complete differentiation on the nonmetric multidimensional scaling ( NMS ) ordination graph with upstream reaches composed of relatively sensitive taxa while the lower reaches dominated by tolerant taxa. Multiresponse permutation procedure ( MRPP ) showed significant difference between the two reaches. Macroinvertebrate communities from the dry and wet seasons did not show differentiation on the NMS ordination graph and MRPP did not show significant difference. Both rivers scored low in the South African Scoring System ( SASS 5) and ETH bios, indicating ecological degradation. The results suggest that several decades of environmental degradation might have led to impoverished regional species pool, consisting mainly tolerant and generalist taxa constant throughout the year.