Abstract

Levels of trace metals (Co, Cu, Fe, Mn and Zn) were determined in some marine species (Tilapia zilli, Callinectes sapidus and Littorina litorea) collected during different seasons from Ondo coastal region, Nigeria. Both species-dependent variability, residency of the organism and temporal variations were pronounced. A general trend in concentration with the following in decreasing order occurred: Fe > Cu >>> Mn > Co > Zn. An overall elevated concentration of these metals was observed during the wet season particularly in crab and periwinkle when low pH and salinity pervaded in the aqueous medium. The highest bioconcentration factor (BCF in brackets) for Mn (0.21) and Zn (2.33) were observed within crab while those of Co (0.98), Cu (2.19) and Fe (9.95) were observed within periwinkles. Significant correlations (P < 0.05) were recorded between tissue concentrations and size/length of biota. A continuous monitoring program is recommended to establish the studied organisms as bioindicators and to identify future changes to conserve the ‘health’ of this fragile ecosystem.

Key words: Bioindicator, heavy metals, pollution, toxicity, water.