School of Fisheries and Wildlife

Assessment of Water Quality in Some Selected Wetlands of Lake Tana Sub-Basin by Using Physicochemical Parameters and Macroinvertebrate Assemblages

2022-07-01T00:00:00Z

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. 4

Effect ofTana-Beles Hydropower Plant on fish and Fisheries, Ethiopia

2025-02-01T00:00:00Z

Effect ofTana-Beles Hydropower Plant on fish and Fisheries, Ethiopia Melkamu Aginchew Hydropower is crucial for meeting Ethiopia’s energy needs, but it can have ecological and socio-economic impacts if not managed properly. This study was conductedin the Tana Beles Hydropower Plant.The study aimed to assess the impact of theTana Beles Hydropower Plant on fish diversity, composition, and the socio-economic conditionof fishers. Data were collected through a combinationof field sampling, key informant interviews, focus group discussions, and questionnaires. Physico-chemical parameters were measured insitu using a portable multi-parameter device, and fishes were collectedusing gillnets of various mesh sizes.Fish species were identified using taxonomic keys, and their lengths and weights were recorded. Significant differences in physico-chemical parameters were observedbetween sampling sites across all parameters.A total of 374 fish specimenswere collected,of these 271 from upstream and 103 from downstream predominantly belonging to the cyprinidae family.Shannon diversity was higher at the upstream sites (H' = 1.66) than at the downstream (H'= 1.41), indicating moderate diversity.The species that dominated the upstream sites were Labeobarbus brevicephalus (46.0%) while, Labeobarbus beso (0.24%), was the least abundant. In contrast, Labeobarbus nedgia (42.85%) dominated the downstream sites, while Oreochromis niloticus (2.75%) was the least abundant. Length-weight relationships varied among species, Labeobarbus intermedius (upstream) and Labeobarbus nedgia (downstream) exhibiting isometric growth, while others displayed allometric. Fulton’s Condition Factor exhibited significant site-specific variation in Labeobarbus brevicephalus, but not in Labeobarbus intermedius or Labeobarbus nedgia.Females were more numerous than males.Survey responses revealed that all fishers attributed fish mortality primarily to injuries from hydropower turbines, with 63.2% also reporting increased vulnerability to predation linked to turbine infrastructure. The study recommended adopting fish-friendly designs and monitoring fish movements near intakes to ensure sustainable fish populations and ecosystem health.

Food and Feeding habits of Common carp the introduced Cyprinus Carpio (Linnaeus, 1758) in Lake Ardibo, South Wollo, Ethiopia

2024-07-01T00:00:00Z

Food and Feeding habits of Common carp the introduced Cyprinus Carpio (Linnaeus, 1758) in Lake Ardibo, South Wollo, Ethiopia Tilahun Ayalew This study was conducted to investigate the food and feeding habits of the introduced common carp, Cyprinus carpio, in Lake Ardibo, Ethiopia during dry (February-March) and wet (JulyAugst) months in 2023. Fish specimens were collected by gillnets of various stretched mesh sizes (5cm, 5.8 cm, 6cm, 10cm, 12cm). The gut contents were analyzed using frequency of occurrences and volumetric methods of analysis. A total of 915 fish specimens were collected of which 605(66.12%) guts contained food but 310(33.88%) were empty. The overall sex ratio of female to male C. carpio varied significantly during the sampling period 1:0.72 (p < 0.05). The predominant prey items in terms of frequency of occurrence were zooplankton (72.72%), phytoplankton (66.77%), detritus (66.77%), and macrophyte (39%). Volumetrically, zooplankton (36.27%), phytoplankton (31.41%), macrophyte (15.08%), and detritus (14.81%). However, the contribution of unidentified matters, insects, sand particles, ostracods, gastropods, and fish eggs was low. In the present study, seasonal variation was noted in the diet of C. carpio. Frequency occurrences of phytoplankton and zooplankton varied significantly (𝑋 2 𝑡𝑒𝑠𝑡, 𝑝 < 0.05 ) between dry and wet months. Likewise, the volumetric contribution of phytoplankton, zooplankton, macrophytes, and detritus varied significantly (U test < 0.05) between dry and wet months. Zooplankton, diatom, green algae, macrophyte, and detritus were the major food items during dry months occurring at 87.68, 54.77%, 26.6%, 33.6%, and 61.8% of the guts, respectively, and comprising 53.2%, 15.26%, 4.9%, 10.14%, and 12.7% of the entire volume of food items, respectively. Blue-green algae, green algae, detritus, and macrophytes were the dominant food items during wet months, occurring in 59.42%, 61.3%, 76.32%, and 49.3% of the guts, respectively, and comprising 23.1%, 13.1%, 17.98%, and 24.24% of the total volume of prey items, respectively. The frequency occurrence of detritus and macrophyte was comparable during wet and dry months. Insects and fish eggs contributed less to the diet during the dry months but were absent in the wet months. Schoner Diet Overlap Index revealed there were no significant dietary shifts between juveniles and adults. Both juveniles and adults of C. carpio in Lake Ardibo consumed a variety of prey items. Therefore, based on the result of gut contents; C. carpio is recognized for its omnivorous feeding behavior consuming both plant and animal-based prey. Therefore, C. carpio in Lake Ardibo are deemed suitable candidate fish species for aquaculture development due to their adaptability and versatile dietary habits.

Assessing the Ecological Health of Zarima river using Macroinvertebrate and Fish Communities, North Gondar, Ethiopia

2024-12-01T00:00:00Z

Assessing the Ecological Health of Zarima river using Macroinvertebrate and Fish Communities, North Gondar, Ethiopia Elsa Belete The study was conducted in the Zarima River between March and July 2023. The objectives of the study were to assess the ecological health of Zarima River using macroinvertebrates, fish community, and physicochemical parameters and determine the length-weight relationship the most dominant fish species. Physicochemical sampling were collected using in situ multi parameter probe. Macroinvertebrate specimens were collected using a D-shaped sweep net with a mesh size of 500 µm. Gillnets with diﬀerent mesh sizes 6, 8 and 10 cm and monofilament nets of various mesh sizes(4 and 6 cm) were used to collect fish specimens in both dry and wet seasons. Immediately after capture, the total length(TL), forked length and total weight(TW)of each individual were measured in centimeters and grams, respectively, and their relationship was determined using the power function. A one-way ANOVA and independent t-test were used to describe the mean difference and statistical difference in physicochemical parameters across the sampling sites and seasons respectively. Moreover, canonical correspondence analysis(CCA)was used to visually display patterns in macroinvertebrate and fish distribution in relation to their environmental variables. Also, a principal component analysis was run to ordinate sampling sites in relation to the distribution of macroinvertebrate and fish communities. A total of 292 macroinvertebrate and 253 individual fishes were collected. While Gomphidae was the most dominant(67.47%) taxon among the macroinvertebrates, Cyprinidae was the best-represented family of fishes. Zarima River had higher diversity(H'=1.22) of fish in dry season but lower in wet season which was(H'=0.97). Likewise, L. intermedius was the top(88.1%) in Index of Relative Importance value, indicating its influence in terms of number, weight, and frequency of occurrence in Zarima River. Furthermore, the length-weight relationship for the most abundant species showed that the relationship was strong by discussing the b-value for Garra species(b=3.1015)attain positive allometric growth. However Labeobarbus intermedius and Labeo forskalii attain negative allometric growth. The Zarima River’s diverse aquatic ecosystem, influenced by seasonal and environmental factors, to recommend it need regularly monitor the river's water quality macroinvertebrates and fish populations across different seasons to track changes and respond to potential stressors.