Barnacles and mussels as biomonitors of trace elements: a comparative study

Concentrations of 5 trace elements (cadmium, chromium, copper, lead, zinc) in 3 species of barnacle and the mussel Perna viridis were determined for up to 18 sites in Hong Kong coastal waters. Although each species accumulated differing absolute amounts of metals, qualitative agreement between contamination profiles exhibited by the 4 species for all elements other than cadmium was excellent This was the case even for zinc, which is partially regulated by P. viridis. The relative bioavailabilities of metals other than cadmium to each of the 4 species at the sites studied are thus similar for the barnacle species and the mussel, and a consistent pattern of environmental contamination emerges from these data. By contrast, the bioavailability of cadmium appears to differ between each species; this may be at least partly due to the lack of a marked gradient in cadmium contamination of Hong Kong waters, as shown by previous studies and confirmed here. The differences between the species In trace metal accumulation are discussed, particularly as they relate to the use of barnacles and mussels as biomonitors of aquatic contamination. It is suggested that these species should be further employed in subtropical and tropical nations to establish present levels of contamination and monitor future trends.