Marine Pollution Bioassay by Sea Urchin Eggs, An Attempt to Enhance Accuracy, II

The author proposed in 1971 the use of sea urchin eggs and embryos as indicatory materials in marine pollution bioassay and actually this was applied to the survey of the sea water pollution in the Inland Sea of Japan (Kobayashi et al., 1972).The method was then improved to enhance the sensitivity by using aged eggs (Kobayashi, 1974).Later, it was found that the sensitivity to chemicals varies from fertilization to metamorphosis and the effects on the formation of pluteus were more pronounced than in any other earlier stages (Kobayashi, 1977).It seems that the sperm activity is the most sensitive to chemicals, and that the fertilization and gastrulation are more sensitive than the first cleavage, blastulation and pluteus formation (Kobayashi, 1980).This paper is to show the results of experiments to see the enhancement in sensitivity to chemicals of the fertilized eggs obtained after the pre-treatment of both sperms and eggs, in respective developmental stages from fertilization to pluteus.First, the experiments were made with the chemicals: Cu sulphate, Zn chloride, alkyl benzyle sulphate (ABS) and ammonia chloride and then with the test water collected from around Hatakejima Island.Comparisons were made among the results of experiments with the fertilized eggs derived from normal and differently pre-treated sperms or eggs in various test water checking their sensitivity in respective developmental stages from fertilization to pluteus.Lastly, a new manual and revised ranking are proposed to apply the results of mentioned experiments actually to the bioassay. Materials and MethodsEggs and sperms of Anthocidaris crassispina (A.Agassiz) (in May, July and September) or Hemicentrotus pulcherrimus (A.Agassiz) (in January) were left intact for some time in each test water before they were used for insemination, then the rates of fertilization, first cleavage, gastrulation, pluteus formation and some anomalies