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  • 1995-1999  (2)
  • 1955-1959
  • 1996  (2)
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  • 1995-1999  (2)
  • 1955-1959
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  • 1
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Radioactive waste disposal and nuclear testing concentrated in high latitudes in the northern hemisphere have resulted in the accumulation of radionuclides in Arctic marine ecosystems, but little is known of the consequences for marine biota in these waters. Under controlled laboratory conditions in May through September 1994, we examined the bioaccumulation in sea stars, Asterias forbesi (Desor), or the radionuclides 241Am, 57Co and 137Cs, all of which are important components of disposed radioactive wastes. Experiments at 2 and 12°C determined the relative importance of food (the bivalve, Macoma balthica) and water as sources of radionuclides and assessed the influence of temperature on radionuclide influx and efflux rates. The lower temperature greatly increased the retention of radionuclides ingested with food; for instance, the biological half-life (tb 1/2) of 241Am in the sea stars was 31 d at 12°C, but was virtually infinite at 2°C. Retention of ingested 57Co was also increased at 2°C (tb 1/2=41 d). 137Cs was not accumulated from food. Low temperature significantly reduced net influx rates of 137Cs from water, but did not affect net uptake of 241Am or 57Co. Temperature had little effect on the retention of all three isotopes obtained from the dissolved phase. These experiments suggest that extrapolation of results of previous radioecological studies, conducted at warmer temperatures, to polar or temperate winter environments may be problematic, and that nuclear waste isotopes obtained through trophic transfer may be retained far more efficiently in high latitude marine biota than by fauna from warmer ecosystems.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Marine biology 125 (1996), S. 715-724 
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Mussels have been widely used as bioindicators of coastal contamination, and recent reports have demonstrated that metals are accumulated from both the dissolved phase and from ingested food. In the winter and spring of 1995, we examined the influence of the chemical composition of food (protein content, trace element concentrations and ratios in the diatom Thalassiosira pseudomana) on the assimilation of six trace elements (Ag, Am, Cd, Co, Se and Zn) in the mussel Mytilus edulis (L.). Differences of up to 38% in diatom protein content had no major influence on the assimilation of any trace element or carbon. Protein assimilation in M. edulis examined with a 35S radiotracer was also independent of protein content in the diatoms. Similarly, Se assimilation in mussels was not affected by the different Se concentrations in the diatoms. Cd assimilation increased with increasing Cd concentration, presumably due to higher desorption of Cd under acidic conditions typical of the mussel gut. Zn assimilation was inversely related to Zn concentration in the food particles, implying a partial regulation of this metal in the mussels. There was no evidence of any interaction of Cd and Zn in their assimilation by the mussels. These results suggest that mussels are highly responsive, in an element-specific way, to some components of ingested food (e.g., metal concentration), but other food components (such as the biochemical composition of the algae) have little effect on assimilation.
    Type of Medium: Electronic Resource
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