Heavy metal bioaccumulation in anguillids from rivers in Kenya

Heavy metal bioaccumulation was examined in anguillids from the Athi-Galana-Sabaki (AGS) and Ramisi Rivers in Kenya, which have differing contaminant sources and anthropogenic disturbances. Water and eel tissue samples were analysed for conventional water quality parameters and heavy metals, respectively. Arsenic, lead, and cadmium concentrations were determined using ICP-OES. Results showed that pH was comparable among rivers, but significant differences in temperature, dissolved oxygen, and salinity were observed. Arsenic and cadmium concentrations were comparable between the rivers and exceeded the WHO maximum permissible limits for drinking water. Lead was not detected in the AGS River or upstream in the Ramisi River. Arsenic and cadmium concentrations in muscle and liver tissues differed significantly among anguillid species. Arsenic bioaccumulation was comparable amongst the species, whereas cadmium concentrations differed significantly. Metal concentrations in muscle were negatively correlated to the condition factor, suggesting that eel performance was impacted. Although arsenic and cadmium concentrations in tissues were above permissible limits in freshwater fishes, corresponding bioaccumulation factors were below the recommended values suggesting that eels may be safe for consumption. Further assessment of human health risks is recommended to protect public health.