Shell weight as an independent variable in relation to cadmium content of mollusks

Abstract

Shell weight of molluscs is introduced as alternative parameter for biological monitoring of heavy metals. Variability of metal concentration due to variations in soft-body weight can be eliminated by relating metal body burden to shell weight. A reformed 'Mussel Watch' concept IS outlined. Detailed investigation of Cd in mussels exemplifies advantages of the new approach. The relation of Cd body burden to shell weight is constant in relation to environmental Cd concentration. In contrast, conventional Cd concentration values of soft tissues, in general, are related to the physical condition of mussels. The dependency of condition and Cd concentration on individual size, tidal exposure, spawning, and nutrient supply is documented. Accumulation of Cd in soft tissues and formation of the calcareous shell are discussed in terms of influx of environmental ions and organismic immobilisation, together with their respective organic ligands.

Metal and metallothionein level in the heat-treated cytosol of gills of transplanted mussels Mytilus galloprovincialis Lmk

“…At the beginning of our field study the mussels' age was defined as 121 months. Shell mass was selected as additional indicator of age, due to the fact that the calcareous shell continues to be formed even when the length increments are not observed (Fischer, 1983). Our observations confirm that during 12 months of caging, mussels' length increased on average from 5.2 to 5.9 cm, while the shell mass increased on average from 4.5 to 7.0 g.…”

The Influence of the Biometric Parameters on Metallothionein and Metal Level in the Heat-Treated Cytosol of the Whole Soft Tissue of Transplanted Mussels

“…. Evidently, the shell mass has increased during one year of observation, thus reflecting the ageing process of mussels, as was previously suggested by Fischer (1983). Dry whole soft tissue mass varies within the deployment period, but it has not increased after one year at any of the deployment sites.…”

“…But, in the small (shell mass up to 5 g) and medium individuals (shell mass in the range from 5-20 g), soft body mass still increases, in the first case faster, and in the second slower than the shell mass (Fischer, 1983). Thus, when the mussels' shell masses are in the range from 4.5 to 8.0 g, as in our study, it is still expected to observe the increase of soft tissue mass in relation to mussel's ageing.…”

“…At the beginning of our field study the mussels' age was defined as 121 months. Shell mass was measured as an additional indicator of age, due to the fact that the calcareous shell continues to be formed even when the length increments are not observed (Fischer, 1983).…”

Levels of trace metals and effect of body size on metal content and concentration in Arctica islandica L. (Mollusca: Bivalvia) from Kiel Bay, Western Baltic

“…Subsamples of nearly 20 mg were weighted and digested in quartz vessels with TEFLON covers to allow acid reflux to take place. The digestion mixture used was composed of 1:1, v:v, nitric:perchloric super pure acids (Fischer, 1983). The volume of the mixture used was always 10 times the sample mass.…”