Heavy metal contamination is a major global problem threatening the sustainability of marine (aquatic) environments, biota species and humans who ingest resources from the contaminated ecosystems. This study aimed to investigate the seasonal variation, bioaccumulation, and associated human health risks of selected heavy metals in oysters (Crassostrea gasar) from Iko River marine ecosystem, Nigeria. The heavy metals considered are; zinc, lead, cadmium, copper, nickel, vanadium, cobalt and chromium. The heavy metals were determined using inductively coupled plasma – optical emission spectrometer (ICP-OES). The results indicated bioaccumulation of the metals determined in Crassostrea gasar in the order of magnitude (from the five sampling sites) Zn > Fe > V > Cu > Mn > Ni > Pb > Cr, whilst, Co, Ag and Cd were below detection limit. By the bioaccumulation factor (BCF) quality guidelines ranking scheme the present study has indicated that Zn, Mn, Cd, Pb, Ni, have low concerns (BCF < 250) at the five sampling sites. This study demonstrates that Crassostrea gasar in Iko River significantly bioaccumulate heavy metals, with zinc showing the highest levels across seasons. Although Cd and Co were not detected, several metals exceeded recommended dietary limits, posing health risks to consumers. The findings highlight oysters as effective bioindicators and underscore the urgent need for regular monitoring and remediation strategies in Eastern Obolo coastal ecosystems.
Etesin et al. (Sun,) studied this question.