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Browsing by Author "Langston, W.J"

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  • Effect of temperature and size on metallothionein synthesis in the gill of Mytilus galloprovincialis exposed to cadmium
    Publication . Serafim, Angela; Company, Rui; Bebianno, Maria João; Langston, W.J
    Although the degree of metal contamination is expected to be a primary determinant of metallothionein (MT) induction in marine mussels, at least at polluted sites, variability caused by temperature, and biotic factors such as size, may need to be considered when interpreting field data. To test the effects of these variables, mussels, Mytilus galloprovincialis, of different sizes (small: 3.5+/-0.5 cm and large: 5.2+/-0.7 cm) were exposed to Cd (100 mug 1(-1)) at different water temperatures (5, 18 and 25 degreesC) for 34 days. Resultant Cd and MT concentrations in gills were shown to be size dependent and increased significantly with temperature. At the highest temperature tested (25 degreesC) there appears to be a disproportionate effect on Cd accumulation, which raises MT synthesis to exceptionally high levels. The effect of size on MT concentrations was also temperature-dependent: at 18 and 25 degreesC, large mussels exhibited higher MT levels than smaller individuals, whilst at 5 degreesC there were no significant differences between contaminated and control mussels, in either size-group, as a result of the reduced level of MT production at this temperature. When considering the use of MT levels in mussels as a biochemical indicator of metal contamination, the potential influence of factors such as size and temperature on MT-metal relationships needs to be considered. Samples should be of uniform size as far as possible, and collection should be limited to a fixed season (avoiding climatic extremes) to ensure that the effects of these factors on baseline levels of MT is minimised.
    2002Journal article Restricted access Show more
  • Routes of TBT uptake in the clam Ruditapes decussatus. II. Food as vector of TBT uptake
    Publication . Coelho, Márcio; Bebianno, Maria João; Langston, W.J
    Marine bivalves are exposed to contaminants via the aqueous phase, sediments and food. Nevertheless, the relative importance of these phases as uptake vectors of contaminants in these marine organisms has not been well studied. Phytoplankton concentrate contaminants from seawater and given their position at the base of most marine food webs, these algal cells may play critical roles in the transfer of contaminants to higher trophic levels. This study assesses the relative importance of microalgae as a vector of tributylin (TBT) uptake in the infaunal, suspension-feeding bivalve Ruditapes decussatus. Accumulation of TBT via the algal diet was determined by experimental exposure of R. decussatus to 14C-TBT labelled phytoplankton Isochrisis galbana, for a period up to 60 days. The digestive tract of these clams initially accumulates TBT preferentially from food. After a few weeks of exposure, internal remobilization results in a more widespread partitioning of TBT amongst tissues.
    2002Journal article Restricted access Show more