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(M/EH006) Combined toxicity of dissolved mercury with copper, lead and cadmium on embryogenesis and early larval growth of the Paracentrotus lividus sea-urchin. Fernandez, Nuria1, Beiras, Ricardo1, 1 ABSTRACT- The individual and combined toxicity of dissolved mercury, copper, lead and cadmium has been investigated by using the Paracentrotus lividus sea-urchin embryo-larval bioassay. With this aim embryogenesis success and early larval growth have been recorded after incubation of fertilised eggs in seawater with both single metals and binary combinations of mercury with every other metal. From these results additive indices have been calculated. For individual metals the ranking of toxicity was Hg>Cu>Pb>Cd, with EC50 values of 0.11, 1.1, 2.5 and 82 Key words: toxicity test, sea urchin, trace metals, interaction |
M respectively. When lowest effective concentrations (LOEC) were calculated from early larval growth data, LOEC values were approximately three times lower than EC50 for Hg, Cu and Pb, and more than two orders of magnitude lower for Cd, stressing the danger of underestimating toxicity when only lethal effects are recorded. Marking & Dawson's additive indices ranged from 0.10 to 0.19, indicating additive effects with a slight trend to synergism which was statistically significant for the Hg-Pb combination only. Hayes' additive indices were within the margins considered acceptable for additive interactions. Therefore, the present findings support that embryotoxicity of combinations of mercury with other trace metals in the marine environment may be predicted within a 20% error margin by adding the toxic units of the metals present.