Cytotoxic assessment of Nile tilapia (Oreochromis niloticus) from a domestic wastewater canal with heavy metal contamination

Abstract

© 2017 The Japan Mendel Society. The study aimed to assess water quality parameters and heavy metal contamination in water, sediment and Nile tilapia (Oreochromis niloticus). Heavy metal concentrations in water were compared to Thailand's standard limits, and chromosomal aberrations in O. niloticus from contaminated water were compared with O. niloticus from an unaffected area. The samples were collected from a domestic wastewater canal, water quality parameters were assessed, and heavy metal concentrations (Pb, Cd, Cr, Cu, Fe, Mn, Ni, and Zn) in the water, sediment and fish were analyzed by inductively coupled plasma optical emission spectrometry (ICP-OES). The water quality parameters did not exceed standard values. The concentrations of heavy metals in the water and sediment did not exceed Thailand's standards, but the Ni concentration in the water was higher than the standard limits. Similarly, heavy metal concentrations in O. niloticus were also below the standard limits. Only the Cr concentration in O. niloticus tissues exceeded the standard limits. The diploid chromosome number of O. niloticus from both areas was 2n=44 and the chromosomal damage of O. niloticus in the affected area was higher than that in the unaffected area. There were six types of chromosomal aberrations: single chromatid break, single chromatid gap, centromeric gap, fragmentation, deletion and dicentric chromosomes. The most common chromosomal abnormality in the fish samples from the affected area was single chromatid gap, and the difference in chromosomal breakages in O. niloticus between the areas was significant (p<0.05).