HIGH-SENSITIVITY OF SKELETOGENESIS TO PB IN THE ASTEROID ASTERIAS-RUBENS (ECHINODERMATA)

The effects of lead bioaccumulation on skeleton morphogenesis was asce rtained in the common North Atlantic asteroid Asterias rubens. Regener ation of adambulacral spines was used as an experimental model. Spine regeneration was initiated in asteroids exposed experimentally to 1, 5 , 20, or 50 mu g Pb 1(-1) for 15 days. Pb bioaccumulation in the analy sed body compartments was dose-dependent. Measures by atomic absorptio n spectrometry and proton induced X-ray emission microscopy showed tha t lead effectively reached the skeleton. Scanning electron microscopy showed that skeleton morphogenesis was affected: the trabeculae were s horter and more stocky, secondary brides were not formed after 15 days , trabeculae outline was irregular and mineral deposition was highly r educed. The size of the regenerates was significantly smaller in the i ndividuals exposed to concentrations greater than or equal to 5 mu g P b 1(-1) (up to 70% reduction). Alkaline phosphatase activity was measu red as a marker of the functional state of the body wall: it significa ntly decreased (30% reduction) only in individuals exposed to 50 mu g Pb 1(-1). These results indicate that, in comparison with other phyla, skeletogenesis in asteroids is particularly sensitive to Pb and that Pb toxic effects could arise directly from the incorporation of the me tal in the skeleton. (C) 1997 Elsevier Science B.V.