Heavy metals concentrations and burden in the bivalves (Anadara (Senilia) senilis, Crassostrea tulipa and Perna perna) from lagoons in Ghana: Model to describe mechanism of accumulation/excretion
Keywords:
Heavy metals, bivalves, marine, lagoons, seasonal variation, accumulation, Ghana.Abstract
Seasonal sampling of the bivalves: Anadara (Senilia) senilis (n = 260), Crassostrea tulipa (n = 220),
from two ‘open’ lagoons (Benya and Ningo) and a ‘closed’ lagoon (Sakumo), and Perna perna (n = 170),
from rocky shores adjacent to Benya and Sakumo, were analyzed for their total Cu, Zn, Fe, Mn, Cd and
Hg concentrations and total body burden (that is concentration multiply by total flesh weight) . Median
concentrations for cockles were: 5, 38, 710, 10, 0.22 and 0.20 µg/g dw respectively. Cd and Hg levels in
dry season samples were higher than those in wet season. While Zn and Fe dry season levels were
lower than wet season with no variation in Cu and Mn. Median total body burden in cockles were: 3.3,
30.5, 370, 5.2, 0.28 and 0.13 µg respectively. Geographical variations observed were mostly due to size
distribution rather than the ecological differences between stations. Log-transformed regression
relationships between body burden and size were used to compare the species. Relationship between
condition index, body burden and concentration were used to develop a model to describe mechanism
of accumulation/excretion.
