Effects of Salinity Fluctuation Frequency on the Growth, Molting Rate and Hemolymph 20-Hydroxyecdysone Concentration in Juvenile Chinese shrimp, Fenneropenaeus chinensis

This experiment was conducted to examine the effects of salinity fluctuation frequency on the growth, molting rate and hemolymph 20-hydroxyecdysone (20-HE) concentration for juvenile Fenneropenaeus chinensis with an initial wet body weight of 1.115 g±0.012 g. The salinity of the control treatment (represented by D0) was 28 throughout the experiment, whereas treatments D2,D4, D6 and D8 were subjected to different salinity fluctuation frequencies of 2, 4, 6 and 8d, respectively. The range of salinity fluctuation was 4. The salinity in treatments D2, D4, D6 and D8 was kept at 28 for 2, 4, 6 and 8d, respectively; each original salinity was decreased abruptly to salinity 24, which first lasted for another 2d and was then raised to its initial value 28. This constituted a salinity fluctuation cycle and afterwards the cycle repeated. It was found that: 1) The weight gain of shrimp in treatment D4 was 202.9% and significantly higher than that in treatment D0 (P<0.05). The molting rate in treatment D2 was the lowest, while that in treatment D6 was the highest and significantly higher than those in treatments D0 and D2 (P<0.05). 2) The hemolymph 20-HE concentration of shrimps in all treatments was at low levels and increased first gradually during the inter-molt period and then increased sharply. It reached a peak value during the pre-molt stage, and then decreased abruptly during the post-molt stage when the lowest level occurred. 3) During the post-molt stage, the hemolymph 20-HE concentration in treatment D2 was 7.47pgμL-1 and significantly higher than that in treatment D0(P<0.05). There were, however, no significant differences in hemolymph 20-HE concentration among all five treatments during the inter-molt stage (P>0.05). During the pre-molt stage, the hemolymph 20-HE concentration in treatment D6 was significantly higher than that in treatment D0(P<0.05), whereas the hemolymph 20-HE concentration in treatment D2 was significantly lower than that in other treatments (P<0.05). Adequate salinity fluctuation promoted the molting rate through increasing hemolymph 20-HE concentration at the pre-molt stage.     

日粮水平对周期性变温模式下刺参生长和能量收支的影响

变温对不同水生生物生长的影响有所不同,对部分种类具有明显的促进作用,而由于种类或温度设置等差异,研究结果各有差异.刺参(Apostichopus japonicus)在生长和生理水平上对一定程度上的符合自然水域温度波动曲线的周期性变温具有积极响应,作者研究在2个变温平均温度(均温15,18 ℃),5个日粮水平(饥饿;0.3%初始体重;0.6%初始体重;0.9%初始体重;1.4%初始体重)下刺参幼参的生长、摄食和能量收支.结果表明,在饱食条件下,刺参在变温条件下生长率高于相应的恒温对照,(15±3) ℃下差异达到显著水平.在各日粮条件下,(15±3) ℃下刺参的生长率均高于(18±3) ℃下对应日粮组.随日粮水平的升高,食物吸收率(FI)和食物转化率(FCE)显著升高.食物转化率变温组均大于恒温处理组,且在均温15 ℃下变温组显著高于恒温组(P<0.05).在能量分配模式中呼吸能占比例最大,且随变温均温升高而显著增加,是造成不同温度下刺参生长率变化的主要因素之一.在(15±3) ℃和(18±3) ℃下,刺参以能量表示的维持日粮值分别为0.39%和0.51%,与相关资料报道的恒温状态下维持日粮相比,一定程度上的变温并不会提高刺参的维持代谢.     

Numerical simulation of nearshore circulation on field topography under random wave environment

In order to investigate surf zone hydrodynamics through two-dimensional numerical simulations of nearshore circulation under random wave environment, a nearshore circulation model, SHORECIRC, and a random wave model, SWAN, were combined and utilized. Using this combined model, a numerical simulation of the October 2, 1997 SandyDuck field experiment was performed. For this simulation, field topography and an input offshore spectrum were constructed using observed data sets synchronized with the experiment. The wave-breaking model in SWAN was modified by using breaker parameters varied according to bottom slope. The simulation results were compared with the experimental data, which revealed a well-developed longshore current, as well as with results using other combinations which were SHORECIRC and its original monochromatic wave-driver, and SHORECIRC and the default of SWAN. The results from the novel combined model agreed well with the experimental data. The results of the present simulation also indicate that alongshore field topography influences shear fluctuation of longshore currents.     

海平面波动中的岩溶响应——以塔里木盆地牙哈-英买力地区下古生界为例

岩溶成因碳酸盐岩油气储层的展布预测,是全球石油地质家一直在探索的热点问题之一。下古生界岩溶型碳酸盐岩储层是盆地内极有潜力赋存大油气田的储集体。本文以岩溶类型研究为基础、以海平面波动史构建为切入点、以塔里木盆地下古生界为例,开展了海平面波动中的岩溶响应研究。分析表明,塔里木盆地早古生代海平面下降期均发育了准同生岩溶。准同生岩溶为埋藏岩溶和风华壳岩溶提供了良好的溶蚀介质输导孔隙。地球物理资料显示,塔北下奥陶统的两期风化壳岩溶叠加于先期的准同生岩溶作用之上。海平面波动史的重建及岩溶格架分析表明,塔里木地区早古生代海平面波动与岩溶发育呈现良好的耦合关系。海平面变化是控制塔里木盆地下古生界岩溶储层发育的一个重要的因素。     

Conversion of kinetic energy from synoptic scale disturbance to low-frequency fluctuation over the Yangtze River valley in the summers of 1997 and 1999

In order to investigate the conversion of kinetic energy from a synoptic scale disturbance （SSD; period≤seven days） to a low-frequency fluctuation （LFF; period〉seven days）, the budget equation of the LFF kinetic energy is derived. The energy conversion is then calculated and analyzed for the summers of 1997 and 1999. The results show that the energy conversion from the SSD to the LFF is obviously enhanced in the middle and lower troposphere during the heavy rainfall, suggesting this to be one of mechanisms inducing the heavy rainfall, although the local LFF kinetic energy may not be enhanced.     

中国区域地理、地形因子对降水分布影响的估算和分析

不同与以往基于最小二乘的多元线性回归方法,本文首次尝试将新型的第二代回归分析方法——偏最小二乘回归分析方法应用到中国区域的降水建模中．利用区域内394个气象观测站建站到2000年45年(及以上)的降水资料,建立了一个简单的年、季降水量和地理、地形因子(包括纬度、经度、地形高程、坡度、坡向和遮蔽度)的关系模型,估算了区域降水量中地理、地形的影响部分,并分析了这种影响的特征．结果表明,用此方法建立的模型能够解释70%以上的因变量的变异,相关系数基本都在0.84以上,经交叉有效性检验,模型的回归效果较显著．分析表明,在多元线性回归不适用的情况下,本文基于偏最小二乘法的简单模型能够比较准确地定性、定量地再现实际降水分布．     

强迫耗散非线性系统的局域阻塞流型

本文将正压涡度方程约化为强迫耗散的KdV方程,求得了该方程的一个定常解.这个定常解描述了非绝热加热、耗散、非线性平流和线性频散共同作用所形成的阻塞流型.在确定性初条件、随机性初条件和随机热源扰动的情况下,积分时间大于60天的三组试验表明:该阻塞流型闭合高压中心位置维持定常,而阻高中心强度的演变显示出清晰的准两周或一个月左右的低频振荡现象.     

重力流冷锋及其受地形的影响

建立了一个二维非静力平衡模式，通过坐标变换的方法使得模式低层有较高的分辨率。对重力流的模拟结果显示；本模式模拟出的重力流冷锋主要特征，如抬高的头部、头部较强的上升运动以及等位温线密集带与实际大气观测很一致。此外，模式还成功地模拟出了重力流头部后面底层的高速潜流层。应用模拟结果与理论结果对重力流的移动速度进行了对比分析。当考虑地形时，重力流在山前受阻，其头部比不考虑地形时高，且产生了向上游传播的“涌浪”；重力流过山后其头部降低，位温梯度减弱，头部后面的水平速度减小。此外，还对非静力平衡与静力平衡条件下重力流的差异进行了分析讨论。