School of Agriculture and Natural Resources Management

Bioconcentration And Biomagnification of Organochlorine Pesticides by Aquatic Macroinvertebrates and Fish in Estuarine Ecosystems, South Coast, Kenya

2026-06-23T13:59:02Z

Bioconcentration And Biomagnification of Organochlorine Pesticides by Aquatic Macroinvertebrates and Fish in Estuarine Ecosystems, South Coast, Kenya Nyakeya, Kobingi The persistence of organochlorine pesticides (OCPs) in estuarine ecosystems remains a major ecological and public health concern, particularly in tropical regions with intense agricultural activity and weak regulatory enforcement. This study investigated the bioconcentration and biomagnification dynamics of legacy OCPs in estuarine systems along Kenya’s South Coast. Sampling was conducted across multiple stations varying in land use and hydrology, and analyses were performed on water, sediments, and biota including benthic macroinvertebrate trophic guilds and fish (Penaeus monodon) to assess trophic transfer and ecological risk. Sixteen OCPs were detected across matrices, with significantly higher concentrations in biota than in sediments or water. P. monodon consistently exhibited the highest burdens (mean > 200 ng/g), approximately four times higher than in macroinvertebrates: Saccostrea cucullata and Nerita undata. Compounds such as alpha-HCH, o,p′-DDD, Mirex, and p,p′-DDE displayed high biomagnification factors (2.8–3.1), indicative of strong lipophilicity and persistence. Site-specific differences revealed elevated OCP levels in estuaries, suggesting ongoing anthropogenic inputs. Principal Component Analysis (PCA) showed that water parameters such as salinity, conductivity, and total dissolved solids (TDS) were negatively correlated with OCPs, while pH and dissolved oxygen were positively associated with p,p′-DDE and Mirex. These relationships highlight how physicochemical properties influence pesticide transport and bioavailability. Bioconcentration Factor (BCF) analysis confirmed higher accumulation in P. monodon, with moderate BCFs in N. undata and S. cucullata, likely due to sediment-particle interactions. Rhagovelia species acted as intermediate vectors, facilitating contaminant trophic transfer up the food web. Sediment-based ecotoxicological indices further confirmed substantial risk. All OCPs recorded Hazard Quotients (HQs) > 1.0, and compounds like HCB, Heptachlor, and p,p′-DDE exceeded HQ = 1.75, indicating high probability of toxic effects. The Contamination Factor (Cf) and Geo-accumulation Index (Igeo) classified most sediments as extremely polluted, particularly with p,p′-DDD, Mirex, and Cis-chlordane. The Pollution Load Index (PLI) was 2.57, while the Nemerow Pollution Index (PN) reached 420.03; both indicative of widespread non-point and point pollution from sewerage facilities. Hakanson’s Potential Ecological Risk Index (RI) was exceptionally high (31,352.42), far above the critical threshold (RI > 600), with gamma-HCH and p,p′-DDD posing the greatest threat. The Mean Effect Range- Median Quotient (ERM-Q) of 0.119 suggested a 21% probability of adverse effects on benthic fauna. Notably, sediment-bound pesticide levels consistently exceeded ecotoxicological thresholds, reinforcing their potential to drive chronic toxicity in estuarine habitats and disrupt benthic food webs. These results show that legacy OCPs to pose serious ecological threats despite regulatory bans. Elevated residues in P. monodon raise concerns for food safety among coastal human populations reliant on estuarine fisheries and international communities. The study recommends strengthened environmental monitoring, enforcement of pesticide bans, public education, and integrated pesticide and watershed management. Future research should focus on trophic markers, broader contaminant profiling, and ecological restoration to support remediation efforts.

ASSESSMENT OF THE DISTRIBUTION, ABUNDANCE AND DIVERSITY OF PLANKTON AND FISHES ALONG A SALINITY GRADIENT IN THE LAKES NAIVASHA AND OLOIDEN, KENYA

2026-03-06T09:00:06Z

ASSESSMENT OF THE DISTRIBUTION, ABUNDANCE AND DIVERSITY OF PLANKTON AND FISHES ALONG A SALINITY GRADIENT IN THE LAKES NAIVASHA AND OLOIDEN, KENYA GUTO, CAROLYNE KERUBO A study was conducted monthly, for a year along a transect in seven sampling sites. The objective of the study was to assess the distribution, abundance and diversity of plankton and fish along a salinity gradient in the Lakes Naivasha and Oloiden. Physical-chemical parameters such as lake depth were measured in situ and Water samples for nutrients and others were collected for laboratory analysis. Fish were caught using gill nets and Oreochromis niloticus gut sample was taken immediately for later laboratory analysis. The Lake Oloiden had a depth and secchi depth of 6.5 ± 0.2 m and 49.3 ± 1.53 cm while the Lake Naivasha’s were 7.73 ± 0.35 m and 61.2 ± 1.3 cm respectively. Temperature, dissolved oxygen, conductivity, salinity and pH for the Lake Oloiden were as follows: 21.54 ± 2.19 oC, 9.58 ± 1.75 mg/L , 0.58 ± 0.1 µS/m, 310 ± 65 ppm and 8.51 ± 0.3, while Lake Naivasha’s were; 21.12 ± 1.91 oC, 6.19 ± 0.94 mg/L, 0.18 ± 0.14 µS/m, 96 ± 20 ppm and 7.58 ± 0.26 respectively. Thirty-two phytoplankton, seventeen zooplankton and 9 fish species were identified. The Shannon-Wiener index, evenness and Margalef’s index were: 0.72 ± 0.1, 0.73 ± 0.06, 3.72 ± 0.77 for the phytoplankton while zooplankton's were; 0.47 ± 0.09, 0.81 ± 0.13, 4.41 ± 0.8 while fishes' were; 0.33 ± 0.3, 0.52 ± 0.44 and 1.52 ± 0.71 respectively. Oreochromis niloticus fed on algae (61.63 ± 17.35 %), detritus (23.11 ± 14.4 %), other plant material (16.64 ± 12.35 %), fish parts (14 ± 5.16 %) and zooplankton (12.92 ± 5.8 %). The diversity index and evenness index were low while richness index was high for the phytoplankton, zooplankton and fish respectively. Salinity and conductivity were lower compared to previous finding. Research should be done on the chlorophyll-a, nutrients and plankton at various depth.

Determinants of Inclusive Agricultural Value Chain and Their Impact on Livelihoods among Contracted Farmers in The Seed Maize Multiplication Programme in Baringo South Sub-County, Baringo County, Kenya

2025-11-12T14:45:33Z

Determinants of Inclusive Agricultural Value Chain and Their Impact on Livelihoods among Contracted Farmers in The Seed Maize Multiplication Programme in Baringo South Sub-County, Baringo County, Kenya Mirasine, Meiguran Integrating smallholder farmers into partnership with agribusiness firms empowers farmers through access to markets and opportunities to increase their income. Maize is a priority food crop for many households in Sub-Saharan Africa. Therefore, the need for quality seed maize offers a great economic prospect for farmers to boost their livelihoods. Despite the economic opportunities that seed maize multiplication programme presents to farmers in Baringo South Sub-County, the poverty index in the sub-county is still high at 52.2% while some farmers have begun exiting the programme. Empirical studies that explore the factors influencing farmer continued participation in the programme are limited. This study examined the determinants of inclusive agricultural value chains and their impact on household livelihoods among smallholder farmers in the seed maize multiplication programme in Baringo South Sub-County, Kenya. The study aimed to assess how production and processing logistics and farmer group dynamics influence farmers’ continued participation, and how participation affects their capacity to sustainably meet family needs. The study adopted a cross-sectional survey design targeting all contracted seed maize farmers in the Sub-County. A multistage sampling technique incorporating proportionate, purposive and simple random sampling was used to select a sample of 366 farmers, out of which 348 participated (95.08% response rate). Data were collected using structured questionnaires and analysed using descriptive statistics, binary and multinomial logistic regression, and Spearman rank correlation. Findings indicated that production and processing logistics specifically, limited irrigation capacity (Odds Ratio [OR] = 0.178, p < 0.000), inadequate post-harvest equipment (OR = 0.523, p = 0.050), and poor seed quality (OR = 0.161, p = 0.004) significantly reduced the odds of continued participation. While good road network increased odds of continued participation by 1.829 (p=0.001). However, farmer knowledge of credit terms (p = 0.141) and access to extension services (p = 0.192) were not statistically significant predictors. In terms of farmer group dynamics, un-transparent leadership (OR = 0.081, p < 0.000) and limited knowledge of contractual arrangements (OR = 0.739, p = 0.049) were associated with reduced participation. Regarding livelihoods, crop losses significantly increased the odds of a farmer being unable to meet basic household needs (OR = 0.485, p = 0.016), while sustainable savings significantly reduced those odds (OR = 1.767, p < 0.000). There was a strong negative correlation between non-transparent leadership and continued participation (r = -0.473, p<0.01), also significant negative correlations between group leadership and post-harvest efficiency (r = -0.124, p<0.05) and credit repayment ability (r = -0.113, p<0.05). A positive correlation was observed between post-harvest processes and farmer payment timeliness (r = 0.136, p<0.05). This study concludes that, while the seed maize multiplication programme offers significant livelihood opportunities, systemic challenges such as unreliable irrigation, post-harvest inadequacies, leadership gaps, limited contractual awareness, delayed payments and production risks undermine sustained farmer engagement and household welfare. This implies that, both institutional (farmer group dynamics) and structural (production and processing logistics) factors interact to shape farmer participation in the seed maize multiplication programme and their livelihood outcomes. Addressing inefficiencies in these broad areas through targeted interventions is critical for enhancing the inclusivity and sustainable impact of the seed maize multiplication programme in Baringo South Sub-County. The study recommends investment in irrigation and rural infrastructure, post-harvest technologies and farmer group leadership capacity building to enhance programme inclusivity and impact.

Emerging Micropollutants Biomonitoring in Peri-Urban Rivers in Kisumu City, Kenya, using the African Catfish (Clarias Gariepinus) As A Sentinel

2025-07-07T13:14:23Z

Emerging Micropollutants Biomonitoring in Peri-Urban Rivers in Kisumu City, Kenya, using the African Catfish (Clarias Gariepinus) As A Sentinel Omondi, Cornel Akwir Aquatic pollution in urban and peri-urban spaces is a worldwide issue, typified by an intricate mix of inorganic and organic pollutants whose effect on aquatic organisms is arbitrary and little-studied. This study investigated the use of Fulton’s Condition Factor, somatic indices, red blood cell parameters, and histopathological alterations in the African catfish as potential biomarkers in evaluating emerging micropollutant exposure and effect in rivers Kisat and Auji, as well as Nyalenda wastewater sedimentation ponds in Kisumu City, Kenya. Ten monthly sampling surveys were conducted at the upstream, midstream and river mouth of rivers Kisat, Auji as well as at pre-treatment and post-treatment ponds of the wastewater sedimentation ponds. Purposive and random sampling designs were used to biomonitor emerging micropollutants in peri-urban rivers in Kisumu City. Selected physical-chemical variables were estimated in situ using a yellow spring instrument (YSI) multiparameter water quality meter. Solid phase extraction – high performance liquid chromatography (SPE–HPLC) technique was used to determine the quantity of selected pharmaceutical mixtures in water and sediments/sludge samples, respectively. Fulton’s Condition Factor, Gill Somatic Index (GSI), Kidney Somatic Index (KSI) and Liver Somatic Index (LSI) as well as level of red blood cell variables including hemoglobin, hematocrit, red blood cell counts, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC) were determined in 485 fish from eight sampling stations. Fish were semi-quantitatively evaluated and the results were used to calculate organ and fish indices to allow statistical comparison between the sampling points. Variations of physico-chemical parameters, concentration of pharmaceutical compounds, somatic indices, red blood cell parameters and histopathological indices among the sampling stations were tested using one-way ANOVA. Integrated reaction of fish to the ecological situations at each sampling station were considered jointly within a multivariate context using redundancy analysis (RDA), principal component analysis (PCA) and Pearson’s correlation coefficient (r). All physico-chemical parameters except turbidity varied significantly (p < 0.05). Conversely, all the selected pharmaceutical compounds that fall into the three pharmaceutical classes (antibiotics, nonsteroidal anti-inflammatory drugs and phosphodiesterase type V inhibitors) were found. Ampicillin and sulfamethoxazole had the highest mean concentration of 975.53 ± 198.56 and 713.02 ± 222.14 ng/L in that order in lotic water samples, while in sediment sulfamethoxazole had the highest mean concentration of 660.88 ± 202.06 ng/g. The findings of the current study clearly show indicators of physiological stress among fish contaminated sites. Linear correlation analysis exhibited a significant inverse association between dissolved oxygen and hemoglobin concentration (r = - 0.50 p = 0.05), hematocrit concentration (r = - 0.39 p = 0.05), MCH (r = - 0.32 p = 0.05), gill index ( r = - 0.46 p = 0.05), kidney index (r = - 0.38 p = 0.05), liver index (r = - 0.40 p = 0.05) and total fish index (r = - 0.43 p = 0.05). Principal Component Analysis additionally revealed a distinct division of sampling locations in two separate categories. Semi-quantitative assessment of the detected histopathological abnormalities showed that gills were extremely impacted organs with symptoms of significant changes. The study recommends the use of somatic indices, red blood cell parameters and gills, kidneys and liver histopathology as an early warning indication of ecological deterioration in rivers that are recipients of inadequately treated domestic, municipal, industrial and agricultural wastewaters.