| With the development of modern industry,the concentrations of greenhouse gases has increased.The excess greenhouse gases have been absorbed by the sea,leading ocean acidification and warming.Based on the forecast of the Representative Concentration Paths（RCPs）given by IPCC.The ocean surface temperature has increased by 0.6℃and decreased in pH by 0.065 units of the oceanic environment according to RCP 2.6 scenario,as well as the ocean surface temperature has increased by 2.0℃and decreased in pH by 0.31 units according to RCP 8.5 scenario in 2100,which caused by the emission of greenhouse gases.The changes of the global oceanic environment have caused a series of adaptive changes in marine life and marine ecosystems.In order to explore the effects of ocean acidification and warming on the growth and development during the early life history of marine fishes,and provide a reference for the study of marine fish ecology in the context of climate change,we chose Nibea albiflora as the target species and carried out the following tests.The corresponding results are listed as follows:1.This experimental study based on the ocean environment forecast in2100 of IPCC,combining with the average temperature and pH in current,we used N.albiflora as a target species to evaluate the effects of climate change on the early life history of marine fishes in the laboratory.There are three experimental gradients of two environment factors in this experiment（T1=26.0℃,T2=26.6℃,T3=28.0℃;pH1=7.8,pH2=7.73,pH3=7.49）,and we adopted 3×3 cross combination and set total 9 groups,that is to say T1×pH1,T1×pH2,T1×pH3,T2×pH1,T2×pH2,T2×pH3,T3×pH1,T3×pH2 and T3×pH3,and we selected T1×pH1 as control group,T2×pH2 as processing group I and T3×pH3 as processing group II.2.We compared the growth,development,and mortality of larval N.albiflora based on the experiment which carried out accroding to the forecast of IPCC,and the results showed that:（1）It took about 25 days to become juveniles for larval N.albiflora that cultured at 24.0℃,whereas it takes only 22 days for those that cultured at 26.0 to 28.0℃.Meanwhile,N.albiflora larvae appear to have larger growth rates at higher temperatures.The mortality of N.albiflora larvae does not show a consistent trend as the surrounding temperature increases,with highest value at 26.6℃and lowest value at 26.0℃.（2）N.albiflora larvae tend to have higher mortality at lower pH levels,with about 3.9%、19.4%and 21.7%of the cultured individuals dead after the experiment at the pH values of 7.80,7.73 and7.49,respectively.Differently,oceanic acidification does not have significant effects on the growth of N.albiflora larvae based on this study.（3）Finally,this study found that the growth rate was 0.71 mm/d and the mortality is 31.1%for larval N.albiflora under RCP 2.6 scenario,and the growth rate increases to 0.76 mm/d,with decreased mortality at 23.9%under RCP 8.5 scenario in 2100.3.We simulated the conditions of ocean acidification and warming in the laboratory to explore the effects of ocean acidification and warming on the otolith of larval N.albiflora,and the results showed that:（1）We got that the otolith formed in the embryonic development stage and its morphological development goes through round,drop-shaped,oval,and the aspect ratio of the otolith is 1.0+in the stage of yolk-sac and pre-flexion,and the aspect ratio of the otolith is 1.3 in the stage of juvenile,and the aspect ratio of the otolith is 1.51.7 in the stage of young stage and becomes stabilization finally.（2）The growth of otolith is synchronous with the growth of fish body,and there was a linear relationship between the length of larval N.albiflora and the major diameters of the otolith:Lt=k·LL,and the change of the parameter k range from 69.209 to 70.464（R2=0.98）.There is a linear relationship between the length of larval N.albiflora and the minor diameters of the otolith:Lt=k·LW,and the change of the parameter k range from 43.888 to 44.543（R2=0.98）.There is a linear relationship between the weight of larval N.albiflora and the weight of otolith:Wt=k·mL,and the change of the parameter k range from 3.4841 to3.9034（R2=0.90）.（3）The otolith formed the first ring on the second day after hatching of the N.albiflora.The relationship between the otolith rings and fishes`growth days is Y=0.9513X–1.0941.We get that the deposition of the otolith rings have the characters of daily cycle.（4）The results showed that there is no effect on the symmetry of left and right otoliths according to ocean warming and acidification（|χ|<0.2）.The oceanic temperature does not have significant effects on the size of otolith,but with the decrease of seawater pH,the size of otolith has an increasing tend.In summary,the size of otolith of N.albiflora have an increasing trend under the marine environment of the year 2100. |
