Abstract:
The tropical earthworm Eudrilus eugeniae was
chronically exposed to hexavalent chromium (Cr) in its
substrate over a concentration range from 0.24 to
893 mg kg-1
. Histological alterations in the body wall
epithelium included cell fusion, reduction in thickness of
the epithelial layer, a marked increase in pyknotic nuclei
and epithelial sloughing. Similar changes were noted in the
circular and longitudinal muscles with damage being
indicated by the prominent inter-muscular cell spaces and
disintegration. Many of these noted alterations intensified
with increasing levels of exposure. It is significant that
some of the changes recorded here were evident even at the
lowest concentration of 0.24 mg kg-1
, an environmentally
relevant concentration. Hence, the observed trends could
be taken as an early warning to the imminent threats of
heavy metal pollution to epigeic earthworm species.
