At a temperature of 23.0 - 24.8℃, the mixed feeding of Japanese anchovy larvae was initiated 24 h before the yolk-sac was exhausted. The point of no return （PNR） was reached on the 6th day after hatching. On the 4t...At a temperature of 23.0 - 24.8℃, the mixed feeding of Japanese anchovy larvae was initiated 24 h before the yolk-sac was exhausted. The point of no return （PNR） was reached on the 6th day after hatching. On the 4th day after hatching, the pectoral angle appeared in both fed and unfed anchovy larvae although it was more evident and sharper in the starved and the PNR stage larvae than in the fed ones. According to observations of larvae collected in the sea, the pectoral angles were evident not only in the larvae of 3.62 - 7.44 mm in standard length, but also in the larvae of 2.70 mm in standard length with remnants of yolk. The pectoral angles became diffuse when the larvae reached 7.84 mm and vanished at 9.86 mm. The pectoral angle cannot be used as a criterion to distinguish healthy from starving larvae.展开更多
The objectives of the present study were to evaluate the yolk-sac and oil globule absorption and point of no return （PNR） ofpikeperch （Sander lucioperca L.） larvae. Artificial propagation ofpikeperch was performed...The objectives of the present study were to evaluate the yolk-sac and oil globule absorption and point of no return （PNR） ofpikeperch （Sander lucioperca L.） larvae. Artificial propagation ofpikeperch was performed at （15±2）℃. Yolk-sac absorption, oil globule absorption, larval growth and the first initial feeding rate were observed to analyze the early growth and to determine the PNR of pikeperch larvae. The total length of newly hatched （0 day after hatching, DAH） pikeperch larvae was （4.25±0.22） mm and the volume of the yolk-sac and the oil globule was （0.30±0.12）mm^3 and （5.14±2.28） 10-2 mm^3 respectively. The yolk-sac and the oil globule were exhausted at 11 DAH and 14 DAH, respectively. Pikeperch larvae began feeding at 8 DAH with an initial feeding rate about 10.0%. From 9 to 14 DAH, the initial feeding rate increased rapidly, and reached its highest （about 82.7%） at 14 DAH. It declined thereafter, 48.9% at 15 DAH and 35.6% at 16 DAH, thus the pikeperch larvae reached PNR by 15-16 DAH. The appropriate first feeding time for the pikeperch larvae is 11-12 DAH, when the initial feeding rate is higher than half of the maximum initial feeding rate.展开更多
厄加勒斯反曲(Agulhas Retroflection,AR)区域是印度洋和大西洋进行水体交换和热量传输的重要通道,此处的热输送过程对印度洋和大西洋的热含量变化有显著的影响。本研究基于高分辨率地球模拟器海洋环流模式(OGCM for the Earth Simulato...厄加勒斯反曲(Agulhas Retroflection,AR)区域是印度洋和大西洋进行水体交换和热量传输的重要通道,此处的热输送过程对印度洋和大西洋的热含量变化有显著的影响。本研究基于高分辨率地球模拟器海洋环流模式(OGCM for the Earth Simulator,OFES)模拟的结果,刻画了1980—2017年AR区域(35.0°S—41.2°S)20.0°E断面上的纬向热输送特征,着重评估了热输送(Q_(H))各项分量的贡献,并探讨了流场变化对Q_(H)的影响。结果表明,气候态下年平均Q_(H)为−0.74 PW(负值表示向西),其中,平均流主导的热输送Q_(MEAN)和非线性过程主导的热输送(Q_(NLR))分别为−0.45 PW和−0.29 PW。流场变化主导的热输送(Q_(VEL))与Q_(H)时间序列相关性最高(r=0.59),方差贡献率高达43.24%。进一步的合成分析结果显示,Q_(VEL)的变化主要受到厄加勒斯流(Agulhas Current,AC)和厄加勒斯回流(Agulhas Return Current,ARC)的经向移动、伸缩和强度变化的调控。当西向的Q_(VEL)较小时,西向AC的减弱幅度大于东向ARC的减弱幅度,使Q_(VEL)整体呈现正异常;而当西向的Q_(VEL)增强时,AC和ARC都有所增强,AC向南拓展、流幅宽度增加,从而使西向Q_(VEL)的量值大于东向,Q_(VEL)整体呈现负异常。此外,本研究采用厄加勒斯反曲点来表征AC-ARC环流系统的位置,比较了反曲点的纬向移动和热输送强弱变化之间的对应关系,结果表明,二者在年代际尺度上存在一定的正相关关系。本研究系统展示了AC-ARC环流系统时空变异与跨洋盆热输送的对应关系,证实AC-ARC的环流位置和结构变化都对热输送过程有重要的调控作用,有助于进一步理解AR区域的环流特征及其潜在的气候效应。展开更多
文摘At a temperature of 23.0 - 24.8℃, the mixed feeding of Japanese anchovy larvae was initiated 24 h before the yolk-sac was exhausted. The point of no return （PNR） was reached on the 6th day after hatching. On the 4th day after hatching, the pectoral angle appeared in both fed and unfed anchovy larvae although it was more evident and sharper in the starved and the PNR stage larvae than in the fed ones. According to observations of larvae collected in the sea, the pectoral angles were evident not only in the larvae of 3.62 - 7.44 mm in standard length, but also in the larvae of 2.70 mm in standard length with remnants of yolk. The pectoral angles became diffuse when the larvae reached 7.84 mm and vanished at 9.86 mm. The pectoral angle cannot be used as a criterion to distinguish healthy from starving larvae.
基金Supported by the Science Fund of Jiangsu Province(No.BY2015039-10)the Fund of Jiangsu Province Collaborative Center of Regional Modern Agriculture&Environmental Protection(No.HSXT219)the Science Fund of Changshu Science and Technology Bureau,China(No.CN201408)
文摘The objectives of the present study were to evaluate the yolk-sac and oil globule absorption and point of no return （PNR） ofpikeperch （Sander lucioperca L.） larvae. Artificial propagation ofpikeperch was performed at （15±2）℃. Yolk-sac absorption, oil globule absorption, larval growth and the first initial feeding rate were observed to analyze the early growth and to determine the PNR of pikeperch larvae. The total length of newly hatched （0 day after hatching, DAH） pikeperch larvae was （4.25±0.22） mm and the volume of the yolk-sac and the oil globule was （0.30±0.12）mm^3 and （5.14±2.28） 10-2 mm^3 respectively. The yolk-sac and the oil globule were exhausted at 11 DAH and 14 DAH, respectively. Pikeperch larvae began feeding at 8 DAH with an initial feeding rate about 10.0%. From 9 to 14 DAH, the initial feeding rate increased rapidly, and reached its highest （about 82.7%） at 14 DAH. It declined thereafter, 48.9% at 15 DAH and 35.6% at 16 DAH, thus the pikeperch larvae reached PNR by 15-16 DAH. The appropriate first feeding time for the pikeperch larvae is 11-12 DAH, when the initial feeding rate is higher than half of the maximum initial feeding rate.
