Experimental cadmium contamination of the echinoid Stomopneustes variolaris (Echinodermata: Echinoidea) : influence of dosage and distribution of the metal in the organism.
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Date
2002
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Abstract
Cd levels were measured in three different body compartments of the echinoid
Stomopneustes variolaris after exposure to concentrations of 5 ug 1l, 20 ug 1l and 50 ug
1l Cd for a period of two weeks. The body compartments investigated included the
intestine, gonads and skeleton. The gonads did not exhibit dose-dependent
bioaccumulation. The levels of cadmium in the intestine and skeleton were significantly
different between the treatments, suggesting that dose dependent bioaccumulation had
occurred in these compartments (except in the skeleton where higher levels -were
recorded for those exposed to 20 ug 1l than those exposed to 50 ug 1l) The levels
recorded in the intestine were higher than those recorded in the gonads and skeleton at the
higher Cd exposures of 20 and 50 ug 1i. The levels accumulated in the gonads and
skeleton were not significantly different from each other. A separate group, exposed to 20
ug 1`1Cd over a period of two weeks, was placed in uncontaminated seawater to
determine if the echinoids were capable of bioremediation. Bioremediation was found to
lower the Cd levels in the gonads, but not in the intestine and skeleton. Cadmium levels
for the three body compartments were also recorded from specimens collected from the
field, indicating the presence of this element in the environment. In addition to using
atomic absorption spectroscopy (AAS), energy dispersive X-ray analysis (EDX) was used
as a comparative technique to detect the presence of Cd in the skeleton of the urchin.
Cadmium was detected in the skeleton with AAS, but not with EDX. S. variolaris proved
to be a capable biomonitor of Cd contamination.
Description
Thesis (M.Sc.Eng.)-University of Durban-Westville, 2002.
Keywords
Echinodermata., Sea urchins., Theses--Civil engineering.