The Effects And Mechanisms Of Sunken Oil On Developmental Toxicity In Offspring Of The Sea Urchin Strongylocentrotus Intermedius

In recent years,with the rapid development of the global economy,oil spills from tank vessels have occurred frequently.Heavy fuel oil(HFO)has become one of the majority oil released from oil spills from tank vessels.HFO has physical properties with a high density and a high viscosity.So,HFO in the marine environment tends to sink and becomes sunken oil.Sunken oil is resistant to degradation and has a longer residual time.Eventually,sunken oil cause longer-term toxic effects on benthic organisms,thus leading to seriously threaten to the survival of its population.Hence,the aim of the present study was to investigate the transgenerational continuous exposure to sunken oil on developmental toxicity in the benthic offspring.In the present study,flow-through oiled gravel columns were prepared to provide closer field approximation of pollution process of suken oil in the marine environment.The sea urchin(Strongylocentrotus intermedius)was selected as model organism.Parental sea urchins were exposed to HFO-oiled gravel column for 21 days and then offspring were continuously exposed to effluents from HFO-oiled gravel column.Offspring cultures were extended from fertilization to 48 h post fertilization.And the total antioxidant capacity and oxidative damage to DNA,lipid hydroperoxides,protein damage of offspring were utilized as oxidative stress biomarkers.At the same time,the morphological evaluation indicators(abnormality,growth inhibition rate,body length)of offspring were observed and recorded.The effects of parents exposed to suken oil on the growth and development of offspring were preliminarily explored.The results of the present study will provide a reference for predicting the changes of sea urchin populations under long-term exposure to suken oil.The results of the study were as follows.(1)Offspring derived from exposed parents further exposed to sunken oil,thus leading to significant increases in the total antioxidant capacity and oxidative damage to DNA,lipid,protein of offspring at 24 h and 48h post fertilization.It indicated that oxidative stress has occurred in the sea urchin offspring.Compared with lipid and protein oxidative damage,DNA oxidative damage is more sensitive,showing that DNA oxidative damage may be used as a sensitive biomarker to measure the level of oxidative stress in organisms.A large number of abnormal and short-length body appeared in the early development stage of offspring due to the suken oil stress.What's more,teratogenic effects became more obvious with the extension of exposed time of offspring.(2)There was no significant difference in the total antioxidant capacity of offspring at 24 h and 48h post fertilization derived from exposed fathers,compared to those derived from control parents.It indicated that paternal exposure experience had no influence on the total antioxidant capacity of offspring.At lower oiled loadings(500,1000,2000 ?g oil/g gravel),offspring at 24 h and 48h post fertilization derived from exposed mothers experienced higher the total antioxidant capacity and lower DNA oxidative damage,lipid hydroperoxides and protein damage.It indicated that maternal exposure experience can reduce the levels of oxidative stress in early-life stage of offspring.In addition,at 4000 ?g/g,there was no significant difference in the levels of antioxidant of offspring at 48 h post fertilization derived from maternal exposure and paternal exposeure,compared to those derived from control parents,and all of them maintained at minimum antioxidant levels,the oxidative damage of them significantly increased at this point.This may indicate that the antioxidant system of offspring have been seriously damaged by the offspring exposed to long-term and higher concentration.(3)The abnormality of offspring at 24 h after fertilization was significantly negatively correlated with the total antioxidant capacity of offspring,while positively correlated with oxidative damage of DNA,lipid and protein of offspring.At the same time,offspring at 24 h after fertilization derived from exposed mothers had higher levels of the total antioxidant capacity and lower levels of oxidative damage,accompanying with lower abnormality,compared to those derived from exposed fathers.However,with development progressed of offspring,the malformed effect of maternal exposure on offspring gradually became serious.Results found that offspring at 48 h post fertilization derived from exposed mothers experienced significant increases in abnormality compared to those derived from exposed fathers,accompanying with higher levels of growth inhibition rate and slower development of body length.It suggested that the negative effects of maternal exposure on the morphological development and growth of offspring became observable at much later(48 h after fertilization).In conclusion,transgenerational continuous exposure to sunken oil can lead to the occurrence of oxidative stress and a large number of abnormal and delayed of offspring.Paternal exposure did not further increase the developmental toxicity of offspring.maternal sunken oil exposure experience reduced the levels of oxidative stress in the early stages of offspring,but in the end the conferred advantage not translate to a fitness for the morphological growth of the offspring.Hence,the present study contributes to the assessment of the effects of long-term suken oil pollution on marine benthic populations.