Browsing by Author "Mwamburi, Job"

Now showing 1 - 4 of 4
  • Publication
    Publication
    Application of phytoplankton community structure for ranking the major riverine catchments influencing the pollution status of a lake basin
    (Wiley, 2020-02-18) Aura, Christopher Mulanda; Odoli, Cyprian; Nyamweya, Chrisphine S.; Njiru, James M.; Musa, Safina; Miruka, Jared Babu; Owili, Monica Ochieng; Omondi, Reuben; Raburu, Phillip; Manyala, Julius; Mwamburi, Job; Ogari, Zachary; Mbaru, Emmanuel K.
    The present study demonstrates the application of a multi‑metric Phytoplankton Index of Biotic Integrity (PIBI) approach for ranking of major river catchments in the Kenyan part of Lake Victoria on the basis of their pollution status. The index utilizes water quality and zooplankton data, phytoplankton diversity, abundance and attributes, as well as literature information. The rivers were sampled from 2016 to 2018 during the wet season (March) and dry season (July). The separation power of the Mann–Whitney U test (p < .05) qualified eight discriminant metrics for phytoplankton samples into a scoring system of 1, 3 and 5, based on high, fair and slight deviation from the best site, respectively, in development of the final PIBI. The Kuja and Sondu‑Miriu rivers had the highest PIBI, signifying least pollution influence on the lake. In contrast, the Yala and Nzoia rivers exhibited the lowest PIBI, representing the catchments with a higher pollution influence on the lake. The fair to poor integrity classes for the major river catchments in the region signified a deteriorating lakescape. The present study presents the preliminary results of using phytoplankton metrics for development of the Index of Biotic Integrity (IBI) approach in the region as a decision‑making support tool for the effective management and sustainable use of water resources in the lake basin.
  • Publication
    Publication
    Organochlorine Contaminants in Nile Tilapia, Oreochromis niloticus (Linnaeus 1758) in Densely Populated Areas of South-Western Kenya
    (2020) Nyaundi, Joseph; Getabu, Albert; Mwamburi, Job; Onchieku, James; Kinaro, Zachary; Ogendi, George; Babu, Miruka; Gichuru, Nicholas
    Concentrations of OCP (Organochlorine Pesticide) residues were determined in cultured Nile tilapia (Oreochromis niloticus) fish in target stations within 1st order wetland of River Kuja, Kenya, between February-November, 2017. The aim was to assess the residue levels in wild and pond cultured fish within a heavily populated agricultural area of South Western Kenya. Biota samples were analysed for selected HCHs (Hexachlorocyclohexane) isomers, DDT (Dichlorodiphenyltrichloroethane) and metabolites and cyclodienes pesticide residues using GC-ECD (Gas Chromatography Equipped with Electron Capture Detector). Most of OCPs observed were BDL (Below Detection Limit) to detectable levels. Larger percentages (> 50%) of DDTs and HCHs were BDL and exhibited consistency, with significant (p < 0.05) differences in mean contamination levels in fish within the wetland, with average muscle tissue pesticides concentrate ranging between 0.229-2.541 g/kg for Nile tilapia. Most dominant isomer in target species was Lindane (-HCH) (3.417 ± 0.983 g/kg) and Endosulfans. Mean Endosulfan sulfate was 2.499 ± 0.071 g/kg d.w. and most frequently detected, and Methoxychlor (2.235 ± 1.459 g/kg), respectively. Mean Aldrin and Dieldrin was 2.028 and 0.574 g/kg d.w. Concentration for DDT and its metabolites was 0.27-3.71 g/kg for p, p’-DDE (DichlorodiphenylDichloroEthene), BDL-1.098 for p, p’-DDD (DichloroDiphenylDichloroEthane), and 0.105-3.518 g/kg for p, p’-DDT with significant differences in mean values and ranges whose levels were below the WHO (World Health Organization) maximum acceptable thresholds of 0.2, 2, 20 and 5.0 g/kg in fish and sea food.
  • Publication
    Publication
    Using the Multi-metric Index of Biotic Integrity methodological approach to determine the major river catchment that most pollutes a lake
    (Aquatic Ecosystem Health, 2021-12-20) Aura, Christopher; Nyamweya, Chrisphine; Njiru, James; Omondi, Reuben; Manyala, Julius; Musa, Safina; Owiti, Horace; Guya, Fredrick; Ongore, Collins; Ogari, Zachary; Mwamburi, Job; Health and Management, Aquatic Ecosystem
    We present the Multi-metric Index of Biotic Integrity methodological approach that allows for the ranking of major river catchments based on pollution status in the Kenyan portion of Lake Victoria, Africa. The study has a broader applicability to all of Lake Victoria, other African Great Lakes, and all lakes that have riverine discharge. The method presented utilizes water quality and environmental data, local knowledge, and pre-existing literature. The parameters considered were sampled from 2016 to 2018 during the dry season (July sampling) and the wet season (March sampling). Separation power of Mann-Whitney U test (p < 0.05) qualified 11 discriminant metrics for both macroinvertebrate and fish samples into the scoring system of 1, 3 and 5 in the formulation of final Multi-metric Index of Biotic Integrity methodological approach. Rivers in the northern section had lower Multi-metric Index of Biotic Integrity methodological approach scores, as compared to southern counterparts. The Multi-metric Index of Biotic Integrity methodological approach ranking herein was validated by community perceptions on pollution levels. River Nzoia catchment emerged as the most polluted, followed by River Yala, River Kuja, and Sondu-Miriu. Siltation, domestic washing, litter and refuse emerged as the main agents of pollution. Management authorities ought to reinforce a balanced utilization of the vital water resources to minimize future impacts, and promote catchment wide practices that ensure ecological health sustainability of the lake ecosystem.
  • Publication
    Publication
    Water quality, phytoplankton composition and microcystin concentrations in Kisumu Bay (Kenya) of Lake Victoria after a prolonged water hyacinth infestation period
    (Lakes and Reservoirs: Research and Management, 2021-12-01) Miruka, Jared Babu; Getabu, Albert; Sitoki, Lewis; James, Onchieku; Mwamburi, Job; George, Ogendi; Chrisphine, Nyamweya; Odoli, Cyprian
    The production of phytoplankton (algal) toxins and their control is of concern because of the need to reduce their negative impacts on water quality and facilitate effective management of algal blooms. The present study was conducted between September 2017 to May 2018, focusing on Kisumu Bay in the Kenyan portion of Lake Victoria, in order to establish the magnitude of potential impacts on phytoplankton composition and microcystin following a prolonged presence of water hyacinth coverage between 2013 and 2018 within the gulf, with an estimated coverage range varying between 644 and 1224 ha. Triplicate samples of physico‑chemical parameters, nutrients, phytoplankton, chlorophyll‑a and algal toxins (N = 88) were collected at eleven sampling sites to determine their spatio‑temporal variability. The main identified algal taxa comprised Cyanophyceae, Bacillariophyceae, Chlorophyceae, Euglenophyceae, Zygnematophyceae and Dinophyceae. The most dominant algal species were Microcystis aeruginosa (25%), Merismopedia spp. (23%) and Anabaena flos‑aquae (16%). Enzyme‑linked immunosorbent assay (ELISA) technique was used to determine microcystin (MC) toxins in the water. Mean MC‑LR and MC‑YR concentrations were significantly correlated (R2 = 0.972), exceeding WHO standards at three sampling sites (Coca Cola, 2.84 ± 4.76; Kisumu pier, 1.78 ± 1.87; Midpoint, 1.44 ± 2.71 μg/L MC–LR). There were significant temporal variations (p < .05) in the SRP, TN, NO3‑N, NO2‑N, NH4‑N, SiO2‑Si, MC‑LR, MC‑YR, dissolved oxygen (DO), total dissolved and suspended solids (TDS; TSS), turbidity, electrical conductivity, Secchi depth, temperature and pH levels. The water depth, TP and DO also vary spatially. The nitrogen to phosphorus concentration ratios differed from the expected N:P ratio of 16:1, indicating a highly eutrophic status. The disproportionate ratio of total phosphorus and total nitrogen in the bay may be responsible for the enhanced cyanobacterial blooms it exhibits. The results of the present study provide useful information and data for formulating regulations for water quality management.