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Lake Victoria is an important source of fish for domestic, regional and global market. Recently, the lake has experienced severe pollution from wastewater and industry. Winam Gulf, located on the eastern side of Lake Victoria Kenya is currently under pollution threat from multiclass pollutants including heavy metals, potentially harming human health and aquatic biodiversity. Therefore, the objective of this paper was to investigate the comparative analysis of heavy metal loading from sewage effluents and Inlet Rivers in the Winam Gulf of Lake Victoria, Kenya using appropriate standard methods. Data obtained show that Nickel average concentration 0.255 mg/l exceeding 0.07mg/l WHO acceptable standards; Lead average concentration 0.048 mg/l exceeding 0.01 mg/l WHO acceptable standard; Cadmium average concentration 0.037mg/l exceeding 0.003mg/l WHO acceptable standard. Among the rivers sampled, River Kisat showed higher concentrations of all the heavy metals analyzed than River Nyando. Heavy metal concentration of the sediment and water samples collected from the different sites were significantly different (p≤0.05). In conclusion, the concentrations of Nickel, Lead, and Cadmium in water samples exceeded WHO standards, especially in River Kisat. The study recommends that there is need to conduct routine assessment of the levels of heavy metals within the gulf, stricter enforcement of regulations governing waste water treatment and discharge and improved efficiency of wastewater treatment plants.

Lake Victoria, the second-largest freshwater lake in the world, provides an important source of food and income, particularly fish for both domestic consumption and for export market. In recent years, Lake Victoria has suffered massive pollution from both industrial and wastewater discharge. Microplastic biomes, pharmaceutical residues, drugs of abuse, heavy metals, agrochemicals, and personal care products are ubiquitous in the aquatic ecosystem of Winam Gulf. These pollutants are known to alter microbial assemblages in aquatic ecosystems with far-reaching ramification including a calamitous consequence to human health. Indeed, some of these pollutants have been associated with human cancers and antimicrobial resistance. There is a paucity of data on the microbial profiles of this important but heavily polluted aquatic ecosystem. The current study sought to investigate the metagenomic profiles of microbial assemblages in the Winam Gulf ecosystem. Water and sediment samples were collected from several locations within the study sites. Total genomic DNA pooled from all sampling sites was extracted and analyzed by whole-genome shotgun sequencing. Analyses revealed three major kingdoms: bacteria, archaea and eukaryotes belonging to 3 phyla, 13 classes, 14 families, 9 orders, 14 genera, and 10 species. Proteobacteria , Betaproteobacteria , Comamonadaceae , Burkholdariales , and Arcobacter were the dominated phyla, class, family, order, genera, and species, respectively. The Kyoto Encyclopedia of Genes and Genomes indicated the highest number of genes involved in metabolism. The presence of carbohydrate metabolism genes and enzymes was used to infer organic pollutions from sewage and agricultural runoffs. Similarly, the presence of xylene and nutrotoluene degradation genes and enzyme was used to infer industrial pollution into the lake. Drug metabolism genes lend credence to the possibility of pharmaceutical pollutants in water. Taken together, there is a clear indication of massive pollution. In addition, carbohydrate-active enzymes were the most abundant and included genes in glycoside hydrolases. Shotgun metagenomic analyses conveyed an understanding of the microbial communities of the massively polluted aquatic ecosystem of Winam Gulf, Lake Vicoria, Kenya. The current study documents the presence of multiclass pollutants in Lake Victoria and reveals information that might be useful for a potential bioremediation strategy using the native microbial communities., Competing Interests: The authors declare no conflict of interest to the research, authorship, and publication of this manuscript., (Copyright © 2023 Sandra Khatiebi et al.)