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Inter-Research |
Assimilation of trace elements
ingested by the mussel Mytilus edulis:
effects of algal food abundance
Wang WX, Fisher NS, Luoma SN
ABSTRACT: Pulse-chase feeding and
multi-labeled radiotracer techniques were employed to measure the
assimilation of 6 trace elements (110mAg, 241Am, 109Cd,
57Co, 75Se and 65Zn) from ingested diatoms
in the mussel Mytilus edulis
feeding at different rates (0.1, 0.49 and 1.5 mg dry wt h-1).
Uniformly radiolabeled diatoms Thalassiosira
pseudonana were fed to mussels for 0.5 h, and the behavior of the
radiotracers in individual mussels was followed for 96 h in a depuration
seawater system. Assimilation efficiency (AE) of each element declined with
increasing ingestion rate and increased with gut passage time. The importance
of extracellular digestion relative to intracellular digestion increased with
ingestion activity, which, when coupled with a decline in AE, suggested that
extracellular digestion is less efficient in metal absorption. Zn
assimilation was most affected by ingestion rate, suggesting that AE may play
a role in the physiological regulation of this metal in M. edulis. In an experiment to simulate
the effects of an acidic gut, lowered pH (5.5) enhanced the release of
elements from intact diatom cells, especially at low particle concentration.
These results indicate that both feeding components of the mussel (i.e. gut
passage time, digestive partitioning) and metal chemistry (i.e. metal release
at lowered pH within the bivalve gut) are responsible for the difference in
the assimilation of trace metals at different food quantities observed in
mussels. KEY WORDS: Mussels . Assimilation
. Bioindicators . Metals . Americium . Cadmium . Cobalt . Selenium . Silver .
Zinc Published in MEPS Vol. 129
(1995) on December 14 |
