Assessment of Water Quality in some Selected Wetlands of Lake Tana Sub-Basin By using physicochemical Parameters and Macroinvertebrate Assemblages

2025-04-07T06:50:13Z

Assessment of Water Quality in some Selected Wetlands of Lake Tana Sub-Basin By using physicochemical Parameters and Macroinvertebrate Assemblages Belaynesh Mekonnen Fresh water is essential to human life and known by their richest species diversity and but pollution from different sources is one of major stressor. The aim of this study was to assess thewater quality in some selected wetlands in Lake Tana sub Basin using physicochemical parameters and macro invertebrate assemblage.The study was conducted on six selected sites during thedry and wetseasons of the year 2020. Macroinvertebrates were sampled from littoral zone at sampling depth of 0.25-0.5 m using standardized kick sampling with a hand D-net (28 cm x 30 cm) and a horizontal transect. All the physico-chemical parameters, except salinity and Chlorophyll-a, showed a significant (p<0.05) temporal variation and the values ranged 6.8 - 7.3, 20.1-24.6 ℃, 5.4-6.1 mg/l, 110.8-129.6 ppm, 121-156.9μs/cm, 0.72-1.36 mg/l and 0.36-0.95 mg/l for pH, temperature, dissolved oxygen, total dissolved solids, conductivity, nitrate and phosphate, respectively. The highest pH value (7.4±1.0) was recorded in the Ras Abay River mouth as well as the highest NO 3 (1.75±0.9 mg/l) and PO (1.44±0.69 mg/l) was recorded in Megech and Gumara River mouth, respectively. A total of 7,247 macro invertebrate individuals belonging to 49 families and 77 genera were collected. The total number of individuals present at each site ranged from 878 at Megech site to 1669 at Wonjeta, and 3,190 and 4057 during wet and dry seasons,respectively. Tubificidae was the most abundant family (1,568 individuals) followed by Thiaridae (626 individuals), Caenidae (575 individuals), Coenagrionidae (499 individuals) and the least Lestidae (479 individuals) family.Gumara and Megech River mouths, and sites around Bahir Dar town were moderately and highly polluted compared to other minimally polluted sites. Generally,rural areas with high agricultural activities such as crop farming and livestock grazing as well as urban areas which directly release domestic wastes into the lake affected water quality of the specific areas. Species diversity, species composition and evenness indexvalues of macroinvertebrates were low at highly disturbed agricultural sites and followed by urban impacted sites. Therefore,agricultural, domestic and industrial wastes should be treated before being released into the lake and solid waste disposal in and around the Lake Tana and its tributary rivers should be discouraged.

Fisheries and Wetland Management

Assessment of Water Quality in some Selected Wetlands of Lake Tana Sub-Basin By using physicochemical Parameters and Macroinvertebrate Assemblages