Ecological Status of Gumara-Maksegnit River as Reflected by Macroinvertebrate Assemblage
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Date
2024-06
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Addis Ababa University
Abstract
Like other tropical rivers, Gumara-Maksegnit River in the Lake Tana sub-basin faces considerable challenges due to agricultural runoff, pollutants, and agro-pastoral activities. Despite these influences, there remains a lack of information regarding the relationship between aquatic macroinvertebrate distribution and environmental parameters within the Gumara Maksegnit watershed. This study, conducted on May 2023 during the pre-rainy season, aimed to address this gap by assessing the influence of water and habitat quality on the distribution and feeding traits of benthic macroinvertebrates across eight sampling sites. Water quality parameters such as temperature, pH, dissolved oxygen, total dissolved solid, conductivity was taken in-situ measurements while ammonia, nitrate, nitrite and phosphate analyzed in the laboratory. Benthic macroinvertebrates were collected using a D-frame kick net and habitat quality was evaluated by using Gitonga method. Statistical analyses, including Pearson's correlation, ANOVA, and Canonical Correspondence Analysis were employed. The ranges for physicochemical parameters were 23.13 - 27.77 °C, 8.4- 9.10 ,5.99-8.23 mg L-1, 289- 472.33 μS cm-1, and 0.033 -0.62 mgL-1 for temperature, pH, DO, conductivity and ammonia respectively. The river water quality parameters were determined to be within acceptable standards for aquatic life. A total of 831 macroinvertebrate individuals from 7 orders and 19 families were identified and counted in this study. The most dominant taxonomic group was Coleoptera, accounting for 58.47% of the total, followed by Mollusca (9.65%). Due to scarcity of stony substrates the presence of EPT taxa was relatively low in the study sites. In terms of abundance of functional feeding groups Predators (Coleoptera, Hemiptera and Odonata) were the most abundant trophic group at most of the sites, with a proportion of 84.71 %, followed by Scrapers (13.83%) and Collector-gatherers (1.32%) while Collector-filters had the lowest representation across all sites with 0.72 %. Gumara Makesegnit River was considered as a moderately polluted as shown by macroinvertebrate communities’ composition and environmental variables. Further research across different seasons and locations along the river is recommended to comprehensively assess its water quality status.
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Keywords
Biomonitoring, Functional Feeding Groups, Gumara, Macroinvertebrates, Water Quality