Songklanakarin Journal of Science and Technology (SJST) (May 2007)
A comparison of metal accumulation by the cnidarian Hydra vulgaris directly from water or
Abstract
The cnidarian Hydra has been widely used to assess the acute toxicity of freshwater pollutants, but very little is known about pollutant accumulation by this animal. The purpose of this study was to measurethe accumulation of the three metals, i.e., copper, cadmium and zinc directly from water and also via its prey and to relate the recorded tissue concentrations to any change in biological activities. It was found thatcopper, cadmium and zinc all were accumulated in the tissues of Hydra exposed directly to the metals in water and also those exposed indirectly through feeding on contaminated prey. The bioconcentration factor(BCF) recorded at 48 hours following direct uptake from water was greatest for copper (773), followed by cadmium (409) and zinc (125), although the greatest increase in body burden occurred with cadmium, Metal body burdens of Hydra fed on contaminated prey (Artemia) increased in the same metal sequence as fordirect uptake from water and the increase was highest (250 times that of control Hydra) for cadmium; however, biomagnification factors (BMFs) were all < 1.0 indicating that there was little potential for increasingaccumulation via the food chain. There was significant inhibition of regeneration and bud production in polyps which had fed on cadmium-containing Artemia but not on copper or zinc- containing Artemia.
