Heavy metals concentration in some organs of tilapia (sarotherodon melanotheron) and mullet (mugil cephalus) harvested from Oginigba/Woji Creek, Port Harcourt, Nigeria

Abstract

Heavy metals concentration in muscles, gills, livers and intestines of two economically valuable fish species, S. melanotheron (Tilapia) and M. cephalus (Mullet) harvested from the Oginigba/Woji Creek for two seasons were investigated. Fish samples were collected and analyzed using the Dry-Ashing method, while heavy metals determination was done with the Atomic Absorption Spectrophotometer (AAS). The mean concentrations (mg/kg dry weight) of heavy metals in fish organs were as follows: S. melanotheron muscles: (Cd)0.06±0.05, (Pb)0.43±0.18, (Fe)59.98±5.36, (Cu)3.84±0.63, (Zn)20.28±3.36 and (Mn)1.64±0.45; gills:(Cd)0.75±0.25, (Pb)1.85±0.49, (Fe)424.28±71.34, (Cu)7.43±1.05, (Zn)51.60±11.52, and (Mn)6.56±1.42; liver: (Cd)0.08±0.07, (Pb)0.57±0.32, (Fe)802.43±65.22, (Cu)190.37±67.77, (Zn)102.37±18.34, and (Mn)4.58±1.19; intestine: (Cd)0.62±0.23, (Pb)1.59±0.47, (Fe)1440.13±223.95, (Cu)17.68±4.41, (Zn)76.00±15.40 and (Mn)18.93±5.66. M. cephalus muscles: (Cd)0.35±0.14, (Pb)1.84±0.55, (Fe)52.45±5.14, (Cu)3.94±0.96, (Zn)22.92±2.26 and (Mn)1.37±0.36; gills: (Cd)0.55±0.18, (Pb)1.56±0.45, (Fe)295.47±68.76, (Cu)7.66±1.31, (Zn)36.58±5.29 and (Mn)11.55±2.28; liver: (Cd)0.06±0.03, (Pb)0.49±0.19, (Fe)487.85±96.50, (Cu)53.99±7.92, (Zn)92.78±13.20 and (Mn)5.77±1.55; intestine: (Cd)0.75±0.30, (Pb)2.30±1.29, (Fe)1005.26±218.42, (Cu)12.95±1.98, (Zn)56.37±7.46 and (Mn)16.90±4.23. The investigation revealed fish organs enrichment of heavy metals most of them above safe limits. The elevated levels of the non-essential metals, Cd and Pb in fish muscles in the selected fish species are pointers to a serious health risk for human consumers, especially during the Dry season, hence the need for restoration and corrective actions to mitigate the toxicity levels of these metals, not only for the wellbeing of the aquatic species but also for the safety of human consumers.