Distribution and Concentration of Several Heavy Metals in Snails (Nerita Lineata) from the Intertidal Areas of Peninsular Malaysia

The aim of this study is to determine the background concentrations of heavy metals in the soft and hard tissues of Nerita lineata collected from the west intertidal area of Peninsular Malaysia and to study its potential use as a biomonitor of Cd, Cu, Fe, Ni, Pb and Zn. From this study, the snails N. lineata, and sediments were collected from 15 sites along the west coast of Peninsular Malaysia from December 2005 until April 2006. Snails collected from each sampling site were dissected and pooled into three parts (total soft tissues, operculums and shells) and were analyzed for Cd, Cu, Fe, Ni, Pb and Zn in addition to sediment samples. The mean metal concentrations (µg/g dry weight) in the soft tissues were 1.18 ± 0.17, 15.43 ± 0.86, 546.21 ± 61.98, 6.69 ± 0.45, 94.42 ± 46.81 and 87.07 ± 4.08 for Cd, Cu, Fe, Ni, Pb and Zn, respectively. As for operculums, the mean metals (µg/g dry weight) were 2.99 ± 0.22, 6.38 ± 0.33, 3 5.05 ± 2.49, 23.34 ± 0.92, 48.22 ± 1.99 and 16.59 ± 1.03 for Cd, Cu, Fe, Ni, Pb and Zn, respectively. In the shells, it was found that the mean metal concentrations (µg/g dry weight) were 3.00 ± 0.23, 6.25 ± 0.54, 70.20 ± 14.04, 23.33 ± l.14, 47.17 ± 2.30 and 13.54 ± 3.21 for Cd, Cu, Fe, Ni, Pb and Zn, respectively. The means of heavy metal concentrations (µg/g dry weight) in sediments were 2.86 ± 0.36, 18.95 ± 3.49, 25499.63 ± 1895.43, 12.35 ± 0.95, 47.24 ± 5.87 and 64.61 ± 4.77 for Cd, Cu, Fe, Ni, Pb and Zn, respectively. The snails were good biomonitors for heavy metals as significant correlations were found between sediments and the soft tissues for Cu (P<0.05) and Pb (P<0.01), while operculums and shells were significantly (P<0.01) correlated with sediments for Cd and Pb. Different patterns of heavy metal distribution were found in the different tissues (shell, operculum and soft tissues) of N. lineata as well as spatial differences and distributions. This shows that the distribution of metals in shells and total soft tissues of N. lineata were not similar and this could be due to different rates of metal accumulation, excretion and sequestration. Since N. lineata can be abundantly found in the rocky shores, below jetties and mangrove trees along the intertidal area of the west coast of Peninsular Malaysia and are accumulative of Cd, Cu, Fe, Ni, Pb and Zn, the snail species is therefore a potential biomonitor of heavy metal pollution in the west coast of Peninsular Malaysia.