Influence of salinity on the early development and biochemical dynamics of a marine fish,Inimicus japonicus

Fertilised eggs of the devil stringer(I nimicus japonicus) were incubated at different salinity levels(21, 25, 29, 33, and 37), and then the hatching performances, morphological parameters, and biochemical composition(protein, lipid and carbohydrate) of the larvae were assayed to determine the influence of salinity on the early development of I. japonicus. The tested salinity levels did not af fect the times of hatching or mouth opening for yolk-sac larvae. However, the salinity significantly influenced the hatching and survival rates of open-mouthed larvae, as well as the morphology of yolk-sac larvae. The data indicated that 30.5 to 37.3 and 24.4 to 29.8 were suitable salinity ranges for the survival of embryos and larvae of I. japonicus, respectively. Larvae incubated at a salinity level of 29 had the greatest full lengths, and decreasing yolk volume was positively correlated with the environmental salinity. With increasing salinity, the individual dry weights of newly hatched larvae or open-mouthed larvae decreased significantly. Newly hatched larvae incubated at a salinity level of 29 had the greatest metabolic substrate contents and gross energy levels, while the openmouthed larvae's greatest values occurred at a salinity level of 25. Larvae incubated in the salinity range of 33 to 37 had the lowest nutritional reserves and energy values. Thus, the I. japonicus yolk-sac larvae acclimated more readily to the lower salinity level than the embryos, and higher salinity levels negatively influenced larval growth and development. In conclusion, the environmental salinity level should be maintained at 29–33 during embryogenesis and at 25–29 during early larval development for this species. Our results can be used to provide optimum aquaculture conditions for the early larval development of I. japonicus.     

包兰铁路沙坡头地段铁路防沙体系的建立及其效益

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沿海地区发展鳄鱼养殖业将大有可为

近年来,鳄鱼养殖业在国外一些国家尤其东南亚国家发展很快,已形成高效益的发达产业。 当前全世界鳄鱼约有20余种,其中中国扬子鳄、泰国湾鳄、美洲短吻鳄、南非尼罗鳄等都是名优品种。尤其是泰国湾鳄,寿命长,体型大,体长可达10米,最大体重可达2吨,鳄鱼经济利用价值很高。由于世界高级皮具业的发展,目前国际鳄鱼皮交易旺盛。据报导,年     

疏散星团NGC6530的成员研究和空间运动

利用上海天文台40厘米折射望远镜照相观测资料所得出的恒星自行,按最大似然原理确定了疏散星团NGC6530天区内恒星的成员概率．分析表明星团成员确定是非常有效的,成员概率p≥0．9的恒星计有250颗．最后,确定了星团的空间运动,并作了简单的讨论．     

广东大量养殖甲鱼

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