Combined Toxicity of Lead and Cadmium on Embryogenesis and Early Larval Stages of the European Clam Ruditapes decussatus

摘要

Individual and combined toxicities of lead (Pb) and cadmium (Cd) were investigated using sperm motility andnembryo-larval bioassay of the clam Ruditapes decussatus. Fertilization and embryogenesis success and larvalnmortality were recorded after incubation of sperm (during 30 min before use for insemination), fertilized eggsn(24 h) and D-shaped larvae (96 h) in seawater, both with single metals and combinations of the two tested metals.nIn spermiotoxicity bioassays, these metals, both individually and in combination, significantly ( p < 0.05) reducednthe fertilization rate only at two higher concentrations that were studied. Median effective concentration (EC50)nvalues were 1033 lg/L (5 lM), 2098.5 lg/L (18.6 lM), and 1442 lg/L (10.8 lM), respectively for individual Pb,nCd, and the mixture (Pb + Cd). Embryogenesis success was also noticeably affected by the single metals and theirnmixture. Median effective concentrations (EC50) values were 256.5 lg/L (1.24 lM), 570.9 lg/L (5.08 lM), andn355.4 lg/L (2.68 lM), respectively for individual Pb, Cd, and the mixture (Pb + Cd). Median lethal concentrationn(LC50) for 96 h larval mortality bioassay registered for individual Pb, Cd, and for the mixture were 453.6 lg/Ln(2.2 lM), 877.8 lg/L (7.8 lM), and 565.6 lg/L (4.3 lM), respectively. Marking–Dawson additive toxicity indicesnwere 0.01, 0.08, and 0.18, respectively, for spermiotoxicity, embryotoxicity, and larval mortality tests, indicatingnadditive effects with a slight trend toward synergism, which was statistically significant only for larval mortality.nThis work shows that both clam embryos and larvae bioassays are useful tools that can be used to evaluatentoxicity of field samples of seawater, sediments, and effluents containing several toxicants.