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Thursday, June 7, 2007 - 10:45 AM
371
A 24 Hour Sediment Toxicity Test Using Hatching Success in Daphnia Magna as an Endpoint
Ebenezer E. Aluma, Ph.D, Student and Patrick R. Hassett, Assistant, Prof. Department of Biological Sciences, Ohio University, 204, Wilson West, Ohio University, Athens, OH 45701
Daphnia magna is widely used as an indicator species in ecotoxicity testing. This study evaluated a rapid ecotoxicity test that could replace the classic 7 day and 21-day chronic tests, in the determination of sediment toxicity. Based on the principle that larval-embryo tests are more sensitive than tests using adult organisms, the proposed test uses the hatching success of Daphnia magna embryos as an endpoint. Embryos in the brood chamber that had attained the ‘single median eye’ stage of development were exposed to several concentrations of sediments spiked with heavy metal contaminants ( ZnCl2, CuCl2, Fe Cl2 and MnSO4 ; 0.0152g/g – 1.52× 10-4 g/g). Hatching success of these embryos was compared to that in control (uncontaminated) sediment. In a second experiment embryos were exposed to sediments from acid mine affected sites and hatching success measured. Results show an inverse relationship between contaminant concentration and hatching success. Hatching success of embryos was inhibited at contaminant concentrations that were sub-lethal to the adults and results were available within twenty-four hours. The rapidity and increased sensitivity of this test could translate into significant savings in terms of time and costs of sediment toxicity tests.