Morphometrical alteration of coelomocytes in the earthworm Lumbricus terrestris.

Earthworms are very important organisms for soil formation and organic matter breakdown in most terrestrial environment. They are key species responsible for moving large amounts of soil from deeper horizons to the surface layers in many ecosystems. These organisms ingest large amounts of. organic matter, and are continuously exposed to contaminants trough their body. Because of their strong interaction with soil, earthworm populations are profoundly affected by soil pollution. In recent years the use of earthworms biological responses (i.e. biomarker) to chemical pollutants has known a growing interest for polluted soil risk assessment. The aim of the present work was the in field validation of a multimarker approach on the bioindicator organism Lumbricus terrestris, a large reddish worm native to Europe. Several biomarkers, either specific or general biomarker, either of exposure or of effect, were determined: metallothionein levels, acetylcholinesterase activity, lysosomal membrane stability, coelomocyte morphometric alterations, micronuclei formation. Animals were sampled in four agricultural soil in the Salento Peninsula (ITALY), characterized by different anthropogenic impacts. In parallel the chemical analysis of heavy metals and aromatic polycyclic hydrocarbons were performed in the soil from the four sites. Obtained results demonstrated the sensitivity of the Lumbricus terrestris biochemical and cellular responses to bioavailable pollutants present in the soil. Moreover, results clearly showed the applicability of the earthworm multrimarker approach in environmental quality monitoring and assessment of the soil