Studies on some Physico-Chemical parameters and heavy metals concentration in the tissues of Oreochromis niloticus and Clarias gariepinus from Amansea River of Anambra state, Nigeria

Abstract

The physico-chemical parameters of Amansea River and the bioaccumulation of heavy metals in two most prevalence fish species Oreochromis nilotics and Clarias gariepinus of the river, were studied from February to September. The fish specimens were procured monthly from artisanal fisher folks from three sampling stations I, II and III. The samples were taking to the laboratory, and were analysed for heavy metals using 240 Version Atomic Absorption Spectrophometer (AAS) method. There were presence of Arsenic (As), Lead (Pb), Mercury (Hg), Chromium (Cr) and Cadmium (Cd) presence in the two fish species tested. The heavy metal ranking in descending order in O. niloticus are As>Pb>Hg>Cr>Cd, with mean concentration mg/kg-1 values of 5.093±0.153, 1.039±0.059, 0.134±0.012, 0.084±0.003 and 0.053±0.007 respectively, while C. gariepinus heavy metal ranking in descending order are Cd<As<Hg<Pb<Cr, with heavy metal mean plus standard deviation (SD) concentration mg/kg-1 values of 2.805±0.008, 2.784±0.058, 0.652±0.003, 0.555±0.008 and 0.365±0.026 respectively. The heavy metal concentration in the tissues of both fish species were higher than permissible limit for fish by the WHO/FAO of 0.2/0.5, 0.30/0.30, 0.05/, 0.05/0.05 and 0.020/0.02 mg/kg-1, rendering fishes from the river dangerous for human consumption. The physico-chemical parameters (To, pH, Salinity, DO, and Conductivity) of 280C, 6.60, 0.25ppt., 6.29mg/L-1 and 84.08us/cm-1 respectively were within the Federal Ministry of Environment standard for fish survival and growth. The high level of heavy metal concentration, calls for serious intervention, monitoring, control and management of activities going on along the river to prevent sicknesses associated with heavy metals bioaccumulation.