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

Abstract

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.