Giant African land snails (Achatina achatina and Archachatina marginata) as bioindicator of heavy metal pollution

Abstract

It is important to always monitor the bioaccumulation potential for heavy metals by organisms especially the edible ones, to assess their potential risk to human health. This study evaluated the bioaccumulation of heavy metals in the shell and soft tissues of snails. Forty snails each were purchased from Ikire and Ore towns. The snails’ shells, feet, digestive tracts and glands were analysed for bioaccumulation of heavy metals using an Atomic Absorption Spectrophotometer. The results showed that the concentration of heavy metals varied with the location and species of the snail. Archachatina marginata from Ore accumulated higher concentrations of heavy metals than A. marginata from Ikire. The concentration of Pb in Achatina achatina and A. marginata from Ikire, and Cd in A. marginata from Ore are slightly above the FAO/WHO permissible limits. Foot bioaccumulated more heavy metals in A. achatina while the digestive gland bioaccumulated more heavy metals in A. marginata. The study concluded that the shell and soft tissues of A. achatina at Ikire and A. marginata at Ikire and Ore bioaccumulated some levels of toxic heavy metals. A. achatina and A. marginata are capable of being used as a sentinel to study the physiological and biochemical imbalances in living organisms arising from the accumulation of heavy metals.   Key words: Bioaccumulation, heavy metal pollution, snails, Achatina achatina, Archachatina marginata.