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Gewählte Diplomarbeit / Masterarbeit:

Gernot Konrad Englmaier (2018): Longitudinal zonation of fish assemblages in a tropical river: Awash river basin, central Ethiopia With taxonomic and ecological considerations on the genus Garra (Teleostei: Cyprinidae).
Diplomarbeit / Masterarbeit - Institut für Hydrobiologie, Gewässermanagement (IHG), BOKU-Universität für Bodenkultur, pp 120. UB BOKU obvsg FullText

Datenquelle: ZID Abstracts
Abstract:
The present study aimed to clarify the fish diversity in the upper and middle Awash river. Patterns of fish assemblages along the longitudinal gradient were studied and the phenotypical variability within the genus Garra was outlined. Therefore, the first 650 km of the river, from the headwaters in the Chilimo forest to the lowland zone in the Afar region were investigated. Physical and chemical water parameter were recorded at each site. Microhabitats and river morphological characteristics were quantitatively estimated along with human activities observed. A combination of fishing gears was used (e.g. electrofishing, beach seine) to sample a variety of mesohabitats. Representatives of the genus Garra were preserved in 96% ethanol and morphometric and meristic characteristics recorded. Water temperature (⁰C) and conductivity (µS cm-1) significantly increased from the source region (S1, max. 17.9⁰C, max. 269 µS cm-1) to the lowland zone (S12, max. 26.2⁰C, max. 993 µS cm-1) but showed unusual gradients possibly related to human activities. The impact of the Koka reservoir was detectable by a decline in water temperature (-2.7⁰C) and conductivity (-253 µS cm-1) but had no observable effect on fish biocenoeses. Fish diversity increased from the rhithron (S1, 2 taxa) to the potamon (S12, 7 taxa), but was highest at site 8 (8 taxa). Two distinct transition zones were observed where fish communities clearly changed along environmental gradients. Garra dembeensis and Garra aff. makiensis were characteristic for the upper reaches, whereas Garra sp. and Micropanchax cf. antinorii were frequent taxa in potamal stretches. Labeobarbus cf. intermedius was most widespread. Based on morphometric and genetic features, 3 distinct groups of Garra could be identified (Garra dembeensis, Garra aff. makienis and Garra sp.). The presence of several morphotypes within each group might reflect specific adaptations to certain abiotically defined environments.

Beurteilende(r): Waidbacher Herwig
1.Mitwirkender: Meulenbroek Paul

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