Accumulation of heavy metals in food plants and grasshoppers from the Taigetos Mountains, Greece

Abstract

Geogenic, as well as anthropogenic heavy metals from distant sources, gradually increase the level of toxic metals in natural environments and these will be increasingly taken up by the plants and transferred further up the food chain. The level of different heavy metals (Hg, Cd, Pb) was studied in the producers (food plants) and consumers [four species of acridid grasshoppers: Calliptamus italicus (L.), Oedipoda caerulesens (L.), O. germanica (Latr.) and Chorthippus( Glyptobothrus) crassiceps(Ramme, 1926)] of a grassland located 1200 m above the sea level in the Taigetos Mountains, Peloponnesus, Greece. The concentrations of heavy metals in the food plants and grasshoppers were in the order Pb > Cd > Hg and the mean concentration of Pb was about 55 and 20 times the concentrations of Hg and Cd, respectively. The solely herbivorous C.( G.) crassiceps had a significantly higher Hg-concentration than in the food plants, but it did not exceed that of Cd and Pb. Cd-concentration in the grasshoppers was significantly higher than in food plants, and female grasshoppers had higher Cd accumulation than males. Lead accumulation in grasshoppers was always lower than in their food plants. The accumulation factors of these elements in the grasshoppers were found in the order Cd > Hg > Pb, thus showing greater affinity to Cd accumulation. Significantly higher concentration of Hg in both sexes of C.( G.) crassiceps than in other three grasshoppers proved this species to be a comparatively better bioindicator of Hg pollution. Elevated concentrations of Cd in both, females and males of all four grasshopper species suggested that any grasshopper, irrespective of the sex, could equally play the role of bioindicator. Studies on the bioaccumulation and biotransfer of different heavy metals showed that the organisms of such distantly located ecosystems were also exposed to measurable amounts of toxic heavy metals.