Browsing by Author "Komba, Richard"

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Cage-Cultured Nile Tilapia (Oreochromis niloticus) Farming: A Third Generation of Pollution in Lake Victoria, Tanzania
(John Wiley & Sons Ltd., 2025-07-23) Komba, Richard; Mwita, Chacha; Kimaro, Esther
This study was carried out along the Mwanza Gulf, Lake Victoria, Tanzania, where water samples for the determination of physico chemical parameters were collected from March to October 2023. NH4+-N, NO3−-N, NO2−-N, and PO4+-P were analyzed using standard methods. Temperature (◦C), electrical conductivity (µS/cm), dissolved oxygen (mg/L), pH, and turbidity were measured in situ. Water temperature ranged from 27.9◦C at Misungwi to 29.1◦C at Nyamagana. Dissolved oxygen (DO) was high at Ilemela (6.70 mg/L) and declined (5.78 mg/L) at Nyamagana. Electrical conductivity and water turbidity increased as the number of cages sampled increased. Nitrate increased from 0.09 mg/L (90 µg/L) at Ilemela to 0.15 mg/L (150 µg/L) at Nyamagana, ammonia concentration from 0.26 mg/L (260 µg/L) to 0.45 mg/L (450 µg/L) at Nyamagana, and phosphate increased from 0.26 mg/L (260 µg/L) to 1.41 mg/L (1410 µg/L). When the results of this study were compared to those reported before 2015, the variations were significant at all levels. We conclude that inputs from cage fish farming are contributing immensely to nutrients loading and thus pollution in the lake. The riparian governments around the lake are urged to take measures that will ensure sustainable cage fish farming without jeopardizing the environmental quality of Lake Victoria with the consequential collapse of the existing fishery.
Polyphosphates: Essential bioenergetic reservoirs and their role as critical nutrient depleters in biological systems
(Scientific Research Archives, 2025) Vulla, Kelvin; Francis, Beatrice; Komba, Richard; Janes, Zabron
Polyphosphates are linear polymers of inorganic phosphate that play a pivotal role in cellular bioenergetics and metabolism across a wide range of organisms. This review article explores the multifaceted functions of polyphosphates as essential bioenergetic reservoirs, highlighting their ability to store and release energy, thereby facilitating various biochemical processes. We discuss the synthesis and degradation pathways of polyphosphates, their influence on ATP metabolism, and their regulatory roles in cellular signaling and stress responses. Additionally, we examine how polyphosphates act as critical nutrient depleters in biological systems, impacting phosphate homeostasis. The interplay between polyphosphate metabolism and nutrient availability is scrutinized, with implications for microbial ecology, agricultural practices, and biotechnological applications. By integrating current research findings, this review emphasizes the significance of polyphosphates not only as energy reservoirs but also as key players in nutrient cycling and environmental sustainability, underscoring their importance in both basic and applied biological sciences.
Prevalence of Zoonotic Bacterial Pathogens and Associated Risk Factors among Cage-Cultured Nile Tilapia (Oreochromis Niloticus) in Mwanza Gulf of Lake Victoria, Tanzania
(NM-AIST, 2025-08) Komba, Richard
Aquaculture has the potential to improve global food and nutrition security, but climate change and poor practices can lead to chemical accumulation and zoonotic bacterial pathogens. This study aimed to identify the prevalence of zoonotic bacterial pathogens and associated risk factors in cage-cultured Nile tilapia in Mwanza Gulf, Lake Victoria, Tanzania. A total of 210 Nile tilapia (Oreochromis niloticus) samples were collected from cages distributed in three districts: Nyamagana (60), Ilemela (70) and Misungwi (80). Tissue samples from the gills, skin, kidney and liver were examined for zoonotic pathogenic bacterial infections. Bacterial isolation and identification were performed using standard conventional bacteriological methods. Additionally, a structured questionnaire was administered to 120 fish farmers to gather information on aquaculture practices, fish health status, and disease management. Water and sediment quality in cage-cultured and control sites were assessed using established physicochemical and sediment analysis procedures. Nine genera of bacteria were identified, including Salmonella spp. (12.5%), Klebsiella spp., Pseudomonas spp. (23.5%), Lactococcus spp. (16.9%), Bacillus spp. (14.7%), Shigella spp., E. coli, Streptococcus spp., and Staphylococcus spp. (16.7%). The gills had the highest bacterial prevalence (28.6%), followed by the liver (16.7%), skin (12.9%) and kidney (6.7%). Bacterial isolates were most prevalent in cages in Ilemela (44.1%), followed by Misungwi (34.6%) and Nyamagana (21.3%), and with significant differences noted (p < 0.001). Additionally, analysis showed that most farms had high stocking densities (> 8 fish/m², 44.4%) and reared Nile tilapia (Oreochromis niloticus) (67.7%). Few farmers regularly measured water quality (16.7%) or removed dead fish daily (20.8%). Key factors influencing total mortality included stocking density (p = 0.013), fish species (p = 0.031), dead fish disposal methods (p = 0.023), and predator bird control (p = 0.016). Water samples from both cage-cultured and control sites showed no significant differences in quality (p > 0.05). Farmed fish and their aquatic environments harbor potentially pathogenic and zoonotic bacteria, posing significant risks to public health and leading to considerable economic losses. Therefore, the implementation of optimal management practices, along with strict biosafety and biosecurity measures, is essential.