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Effects of clam size on
heavy metal accumulation in whole soft tissues of Galatea
paradoxa (Born, 1778) from the Volta estuary, Ghana
S. Amisah1*, D.
Adjei-Boateng, K. A. Obirikorang and K. K. Quagrainie2
1Department
of Fisheries and Watershed Management Kwame Nkrumah
University of Science and technology, Kumasi,
Ghana.
2Department
of Agricultural Economics, Purdue University, West Lafayette
Indiana, USA.
*Corresponding author E-mail:
steveamisah1@yahoo.co.uk.
Accepted 24 May, 2009 |
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The Volta basin clam, Galatea paradoxa, is collected
for food and remains an important affordable protein source
for the riparian communities in the catchment. Clams
accumulate metals in their soft tissues, which can be toxic
to humans when consumed. A study was, therefore, carried out
to examine the concentrations of Mn, Zn, Fe and Hg in G.
paradoxa, at 3 different size classes: small (20 - 40
mm), medium (41 – 60 mm) and large (>60 mm) at Ada and
Aveglo in the Volta estuary area in Ghana. The
concentrations of heavy metals in the clams varied
considerably between the two locations. There were, however,
no significant differences (p > 0.05) in Mn, Fe and Zn
concentrations among the different size classes, indicating
a similar bioavailability of the metals at both locations
and, possibly, an efficient metabolism to keep the
concentrations of Mn, Fe and Zn relatively similar. Mercury
concentrations in the Ada clams varied significantly (p <
0.05) among the different size classes. A Risk Analysis
indicated that the concentrations of heavy metals in the
clams were within acceptable limits and safe for human
consumption.
Key words:
Galatea paradoxa, Volta estuary, heavy metals, size
classes. |
