Effects Of Ocean Acidification And Warming On Physio-ecological Process And Immune Responses Of Sea Cucumber Apostichopus Japonicus (Selenka)

In this study,the impact of ocean acidification(OA)and ocean warming(OW)on sea cucumber Apostichopus japonicus,which is an ecologically and economically important holothurian in East Asian shallow sea ecosystem,were investigated.Four groups of experiment condition were set up which were control group、OW group、OA group and OAW(both OA and OW)group.Three parts of experiment were conducted: the impact of OA and OW on(1)early development;(2)growth and energy budget and(3)immunity of A.japonicus.Results as followed:1、Results of early development showed that fertilization rate significantly reduced in OA group but showed no obvious shift in OW and OAW group compared to control group.Embryos/larvae grew slower and smaller in OA group than control group but faster and bigger at OW and OAW groups.Results indicate that OW can accelerate the development of A.japonicus but OA can suppress it.However,the negative effect of OA can be neutralized by OW indicating temperature,but not pH,is the main factor affecting the early development of sea cucumber.2、Results of growth and energy budget of A.japonicus showed that the growth as well as specific growth rate(SGR)、ingestion rate(IR)、feces production rate(FPR)and food conversation efficiency(FCR)in OW group had no significant difference compared with control group,but the coefficient of size variation(SV)and apparent digestive ratio(ADR)lower than that of control group.Sea cucumber in OA group had the smallest size and lowest SGR and the SV was much higher than that in control group but IR、FPR、ADR and FCR were not affected.In OAW group,SGR、ADR and FCR had no obvious shift compared with control group but IR、FPR and SV were lower than that in control group.In terms of energy,cibation energy(C)、feces energy(F)、respiration energy(R)、growth energy(G)and excretion energy(U)had no significant difference compared with that in control group and the energy allocation model were also not shifted.Sea cucumber in OA group had increased U and the proportion of C lost in U were also enhanced.In OAW group,sea cucumber had the highest C and R,but G、F and U showed no obvious difference compared to control group.The energy allocation model in OAW were also not affected.Results indicate that OW has no impact on growth and energy budget of A.japonicus while OA has an inhibiting effect.However,the negative effect of OA can be counteracted by OW.3、To study the immunity of A.japonicus,the antioxidant ability(SOD、CAT、GSH-Px)and lysozyme level of coelomic fluid were investigated..Results showed that all the immunity indexes tested in this study did not significantly change in all experimental conditions compared with control group.It is indicated that after a long exposure to stress environment,sea cucumber may has the ability to adapt to stress factors so these immunity indexes were not obviously changed,but further research is needed to determine whether the immune system is affected.