Abstract:
Lake Zengena is one of the high-land crater lakes in the North-West highlands of Ethiopia. The hydrologic systems of the high land crater lakes are relatively poorly understood as compared to those in the rift valley. The objective of this study was to assess the species composition, abundance, and diversity of macroinvertebrates in the Lake Zengena Materials used to collect the water and benthic macroinvertebrates. A sampling area of approximately 1m by 1m was taken and bench marked by stone and tree branches. A D-frame net tied with a handling stick was used to collect benthic macro invertebrates. This dipping the net into the sampling area and taking sediments. At each sampling time 0.3m2 (0.3mx 1 m) areas of samples was collected. All the specimens were preservedin 8% formaldehyde solution. Macroinvertebrates samples were collected from the lake habitat between March to June 2018 and were identified to the family levels. The Physico chemical property of the lake water, such as pH, turbidity, conductivity, total dissolved solids, and concentration of ammonia pH. A total of 1080 macro invertebrates belonging to four phyla, and 17 families were collected and identified during the study period. The most dominant phylum was Arthropoda which was represented by class insecta comprising 76.67%. From family level, Chironomidae (24.91%) was the most dominant groups. The total percent contributions of phylum Platyhelminthes, Annelid and Mollusk together were only 23.33%. families such as Planaridae, Hydropsychidae, Hydrophilidae, and Glossifonidae show significant variation ( p < 0.05) in their distribution However, there was no significant variation ( P > 0.05) in the distribution Caenidae, Chironomidae, and Coenagroinidae. The average density of macroinvertebrates in the lake was 250 individuals/m2. The more diversity community was observed in the west side of the lake, The Lake 70% of the macroinvertebrates were similar in the four sites of the Lake. Further study on the abundance of plankton and macroinvertebrates in relation to the physicochemical characteristics of water as well as identification of organisms to the species level should be carried out to see the identified diversity and community structure of the Lake.
