Thesis and Dissertations

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.

Assessment of the effects of Neochetina Weevils’ Species on water Hyacinth (Eichhornia Crassipes) in Earthen Ponds

2024-02-01T00:00:00Z

Assessment of the effects of Neochetina Weevils’ Species on water Hyacinth (Eichhornia Crassipes) in Earthen Ponds Tadele Molla Comfortable water environment for Neochetina weevils’ survival have potential to affect water hyacinth plant parts. The Effect assessment of water hyacinth plant affected by Neochetina weevil species was conducted through physical observation and quantified measures in comparsion treatment and control earthen ponds. The weevils’ affect water hyacinth plant growth and reproduction through feeding different plant parts. The study was conducted in January, 2023; by triplicated (treated and controlled) through planting 35 water hyacinth plants in each ponds and 5 weevils’ per plant treatments that aimed (1) To investigate temporal environmental variability on the survival and development of the weevils’, (2) To determine the abundance of weevils population in the experimental ponds and quantify damage parts of E. crassipes caused by weevils’ and (3) To evaluate the effects of weevils’ on the growth and proliferation of water hyacinth compared to the control ponds. Sampling were design randomly in triplicate sample biweekly gap for 3 months that weevils’ could affect WH; maximum leaf diameter (treatment WH plant decreased by 1.7 ± 0.3cm whereas control WH plant increased by 2.9 ± 0.3cm in mean ), minimum leaf diameter (treatment WH plant decreased by 1.4 ± 0.3cm and control WH plant increased by 2.7 ± 0.3cm in mean ), shoot length (treament WH plant decreased by 9.3 ± 1.7cm and control WH plant increased by 21 ± 1.7cm in mean), root length (treatment WH plant increased by 13.8 ± 1.8cm whereas control WH plant increased by 15 ± 1.8cm rate of increase differ) and fresh WH biomass (treatment WH plant increased by 1258.2 ± 37.8grm and control WH plant increased by 1985.9 ± 37.8grm but rate of increased different). The number of Neochetina weevils’ to feeding scar had direct relationship (y=26.8 + 16.9x).Even though insignificant statistical difference was there between experimental and control groups water quality parameter; WH affect the water quality of ponds water temperature (0.1 ± 0.5 and 2.2 ± 0.5 0 C), dissolved oxygen (0.1 ± 0.3 and 0.4 ± 0.3mg/L), pH (0.2 ± 0.1 and 0.1 ± 0.1) and electrical conductivity (157.7 ± 62 and 105 ± 62 µS/cm) of experimental and control groups respectively. Thus, based on their damage potential and positive impact on water quality parameter, Neochetina weevil species are considered as the best promosing control agent for this invasive weed to Ethiopia water bodies so that before introducing consider area coverage and growth stage of WH.