Effects of Cadmium Exposure on Embryogenesis of Stagnicola elodes (Mollusca, Gastropoda): Potential Consequences for Parasite Transmission



Experiments on the toxicity of cadmium (Cd2+) to the embryonic development of Stagnicola elodes (Mollusca, Gastropoda), obligatory first intermediate host of numerous trematodes of pathogenic importance, were carried out as part of a study on the effects of metal pollution on host-parasite relationships. Freshly laid snail eggs were exposed to Cd concentrations of 0, 0.02, 0.2, and 2.0 mg Cd2+/L, and survival and embryogenesis were examined for 30 days. Mean survival time (± SD) of the control group was 23.1 (± 5.3) days compared with 10.1 (± 3.2) at 0.02 mg Cd2+/L, 3.9 (± 0.7) at 0.2 mg Cd2+/L, and 1.1 (± 0.08) at 2.0 mg Cd2+/L. Mortality patterns of all test groups differed significantly from each other, demonstrating that the percentage of surviving individuals at any given time was inversely related to Cd concentration. Concentration-dependent effects of Cd exposure on snail embryogenesis were noted. While embryos of the control group developed properly and started hatching on day 16, eggs exposed to 0.02 mg Cd2+/L exhibited a prolonged gastrula period and failed to hatch. Eggs in the 0.2 mg Cd2+/L group were blocked in the gastrula stage on day 5, whereas individuals exposed to 2.0 mg Cd2+/L died in the morula stage on the second day. Data showed that Cd severely affects S. elodes embryogenesis. By implication, Cd contamination at concentrations ≥0.02 mg Cd2+/L will thus decrease transmission success of various trematodes by decreasing intermediate host snail abundance.

Copyright information

© Springer Science+Business Media, LLC 2007

Authors and Affiliations

  1. 1.Fluvial Ecosystem Research Section, Aquatic Ecosystem Protection Research Division, Water Science and Technology DirectorateScience and Technology Branch, Environment CanadaMontrealCanada
  2. 2.Institute of Freshwater Ecology and Inland FisheriesBerlinGermany
  3. 3.Toxicology CentreUniversity of SaskatchewanSaskatoonCanada

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