Studeis On Large-scale Artifical Breeding And Ecotoxicolgical Effects Of Copper, Lead And Cadmium On Sinonovacula Constricta

At present,heavy mental pollution has become serious problems in marine environment of China,which results in the deterioration of bivalve resources.The artificial breeding,the fertilization and embryonic development of Sinonovacula constricta were studied in the paper for supplying some useful information on the artificial breeding and scientific sea farming.The ecotoxicological effects of heavy mentals on different life stages of Sinonovacula constricta were also assessed,the results could provide scientific basis for environmental monitoring,water quality standards making,ecological protection and marine shellfish healthy aquaculture.The main research results are as follows:1.Study on the artificial breeding of Sinonovacula constrictaThis study developed artificial breeding of Sinonovacula constricta.The results showed that mastering the gonadial maturity of parental shellfish and propagating in time,could get high efficiency.After 20 days of intensive nursery,the shell length of juveniles were 425⁵00μm under the temperature 20²2℃.2.Cytological observation on fertilization and early embryonic development in Sinonovacula constrictaThe cytology of fertilization and early embryonic development in Sinonovacula constricta were observed by the fluorescent microscope and ordinary light microscope. The result shows that the mature eggs were at metaphase of meiosis I,afer sperm penetrating,the eggs released PB1 and PB2 and finish their meiotic division.The early male and female pronuclei were formed when the second polar body was released.The two pronuclei were expanded to their maximal size and then matched into an association mucleus in the central of the egg,and then began unequal divison.In addition,the abnormal phenomena,like polysperm,polyspindles were observed in the experiment.3.Acute toxicity of heavy mentals to Sinonovacula constrictaAcute toxicity of Cu²⁺,Cd²⁺ and Pb²⁺ to different life stages of Sinonovacula constricta were also assessed.The 96h LC50 for Top shell larvae was 66.557μg/L for Cu²⁺,67.403μg/L for Cd²⁺,1740.415μg/L for Pb²⁺.The 96h LC50 for juveniles was 309.742μg/L for Cu²⁺,154.269μg/L for Cd²⁺,31891.536μg/L for Pb²⁺.The 96h LC50 for matures was 232.138μg/L for Cu²⁺,1005.639μg/L for Cd²⁺,but Pb²⁺ had very low toxicity for killing none after 96h exposure.4.The toxicological effects of Cu²⁺,Cd²⁺ on Sinonovacula constricta juvenilesThe effects of Cu²⁺ ,Cd²⁺ on antioxidant enzyme activitie(sCAT,SOD)and lipid peroxidation in Sinonovacula constricta juveniles were studied.The results showed that different concentrations of Cu²⁺,Cd²⁺ had significant influence on the activity of antioxidant enzyme(CAT,SOD);the contents of MDA in juveniles were higher than controls.