Faculty of Biology, University of Latvia
Hard copy: ISSN 1691–8088
On-line: ISSN 2255–9582
Env Exp Biol (2013) 11: 91–98
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Environmental and

Env Exp Biol (2013) 11: 91–98

Original Article

Algal biomass and nutrient enrichment in the Angereb reservoir, Gondar, Ethiopia

Asefa Mengesha1, Argaw Mekuria2, Azamal Husen1*
1Department of Biology, Faculty of Natural and Computational Science, University of Gondar, P.O. Box # 196, Gondar, Ethiopia
2Environmental Science, Addis Ababa University, Addis Ababa, Ethiopia
*Corresponding author, E-mail: aj07019@lanet.lv


Nutrient enrichment leads to eutrophication in various types of water bodies. This phenomenon is characterized by the presence of large biomass of algae and water weeds, which can decrease water quality in the domestic water supply system. Eutrophication is an anthropogenic factor, and is considered as a global aquatic pollution problem. The aim of this investigation was to assess the trophic status of water in the Angereb reservoir, which is source for domestic water supply in Gondar, Ethiopia. A systematic approach was used to select sampling sites from which sediment, soil and water samples were collected. The trophic status of Angereb reservoir water was mesotrophic (4.2 µg L–1 of chlorophyll a). Nitrogen and phosphorus were main factors causing eutrophication and algal blooms in the reservoir. Dissolved oxygen, pH and temperature of the reservoir were found at a level that was not harmful to aquatic biota. Additionally, the turbidity level was high. Sediments and soils of all selected sub watersheds contained significant amounts of total nitrogen and total phosphorus, leading to nutrient enrichment of the reservoir water. Particularly, the Angereb and Defecha sub watersheds were identified as the main sources of nutrient input to the reservoir. Appropriate soil and water conservation measures are required to reduce the input of nutrients to the Angereb reservoir. In addition, bio-manipulation techniques should be undertaken to impede further growth of algae.

Key words: chlorophyll a, eutrophication, nutrients, reservoir, trophic status, watersheds.

Env Exp Biol (2013) 11: 91–98
 DOI: http://doi.org/10.22364/eeb

Prof. Gederts Ievinsh
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