Effect of toxicants on earthworm haemoglobin levels

Earthworms are important organisms for the soil ecosystem. They are sensitive to toxic chemicals and represent useful bioindicator organisms for soil biomonitoring. Earthworms have no specialized respiratory organs. Oxygen diffuses through the cuticle and epidermal tissues into the haemolymph, which contains haemoglobin. In literature few studies are available on the effect of pollutants on earthworm haemoglobin. The aim of this research was to investigate the effect of commonly used pesticides (copper sulphate and methiocarb) on the haemoglobin levels of the earthworm Lumbricus terrestris. The animals were exposed to the toxicants in laboratory controlled conditions. Haemoglobin level were determined by the Drabkin spectrophotometric method (Drabkin and Austin, J. Biol. Chem., 112 pp. 51–65, 1935). In parallel standardized biomarkers such as tissutal levels of metallothioneins, acetylcholinesterase activity, coelomocyte lysosomal membrane stability were measured. Results showed a significant increase of haemoglobin levels in the animals treated with copper sulphate (P< 0.001). No effect was found in methiocarb treated animals. Obtained results suggest the potential application of haemoglobin levels such as sensible and specific biomarkers of exposure to metals