Improved form of wind wave frequency spectrum

The lower frequency part of the theoretical wind wave spectrum proposed by the authors (Wen et al. , 1988a, b,c) has been improved and the form of spectrum is appreciably simplified. In addition to the field data collected in the Bohai Sea region and used in the previous papers, those obtained in the Huanghai Sea, the East China Sea and the South China Sea have been employed so that the improved spectra can be verified on a more extensive observational basis. Computed results agree with the observations well. Further comparisons have been made between the proposed spectra and the JONSWAP spectrum. Though the two types of spectrum are close to each other in form, the former shows, as a whole, better agreement with the observation than the latter. By introducing an improved relation between the peak-ness factor and significant wave steepness, the spectrum contains only significant wave height and period as parameters. For spectra given in this form, the computed peak frequencies coincide approximately wit     

The Effect of Internal Fluid on the Response of Vortex-Induced Vibration of Marine Risers

Based on Iwan‘s wake oseillator model developed with the classical van der Pol equalion, the differential equation for the response of the vortex-induced vihration (VIV) of the riser considering the effect of the internal flowing fluid and the external marine environmental condition is derived. The effect of the intermal flowing fluid on the response of VIV of the riser is studied by means of the Finite Element Method. The results show that the effect of the internal fluid velocity on the VIV of the riser is strong when the natural frequency of the riser is close to the vortex shedding frequency. In addition, the increase of the top tension can decrease the sensitivity of the riser to the internal fluid velocity.     

Metabolites from mangrove endophytic fungus Dothiorella sp.

Mangroves are special woody plant communities in the intertidal zone of tropical and subtropical coasts. They prove to be a natural microorganisms and new metabolites storage. In the study of mangrove endophytic fungi metabolites, four new compounds, Compounds 1, 2, 3 and 4, as well as a known octaketide, cytosporone B (5), are isolated from an endophytic fungus, Dothiorella sp., HTF3. They all show cytotoxic activities. The elucidation of these structures is mainly based on 1D/2D NMR and ESI-MS spectral analyses.     

投喂频率对南美白对虾(Penaeus vannamei Boone)生长、饲料利用及虾体组成影响的初步研究

本实验选用商品饲料饲养平均初体重为0．09g的南美白对虾，经过30d的生长实验，研究不同投喂频率对南美白对虾生长、成活以及饲料利用的影响。结果表明，随着投喂频率由3次／天增加到5次／天，南美白对虾的增重率、特定生长率和蛋白质效率显著提高，而饲料系数则显著降低，但当投喂频率由5次／天增加到7次／天时，南美白对虾增重率、特定生长率和蛋白质效率并无显著提高。对对虾全虾体主要组成成分的分析表明南美白对虾体主要组成成分并不受投喂频率增加的影响。     

高识别力的微卫星标记系统在鳜属(Siniperca)物种鉴定中的应用

根据自行分离的翘嘴鳜微卫星序列（GenBank登录号：DQ789247-DQ789306）设计并合成20对微卫星引物,对鳜属鱼类4个物种即翘嘴鳜、大眼鳜、斑鳜和暗鳜共80个个体进行了物种鉴定分析.结果表明,20对微卫星引物共检测到293个等位基因,大小在80-301bp之间.它们在4个物种中的多态性位点百分率分别为90%、75%、85%和85%,累积个体识别率和非父排除率均达到0.9999,属于高识别力的微卫星遗传标记系统,可以用来进行鳜属鱼类物种的鉴定分析.UPGMA聚类分析表明,翘嘴鳜与暗鳜之间亲缘关系最近,可归属于第Ⅰ类;大眼鳜为第Ⅱ类;斑鳜独自为第Ⅲ类.本研究可为鳜属鱼类的分类及进化关系、群体遗传结构分析等提供理论支持,为野生原种鳜类遗传多样性的监测和评估以及鳜类优良的种质资源得到合理保护和开发利用奠定基础.     

6-DMAP诱导缢蛏三倍体的研究

用6-DMAP抑制受精卵第二极体排放的方法诱导缢蛏三倍体的试验．结果表明：6-DMAP在100～500μmol／dm^3处理浓度范围内均可以诱导出三倍体，随着药物处理浓度和处理时间的提高，三倍体倍化率和D形幼虫畸形率有不同程度的提高，而D形幼虫孵化率会随之下降．综合来看，在30％卵子受精并出现第一极体，6-DMAP浓度为300μmol／dm^3和处理持续时间为20min时的处理组的处理效果优于其他处理组组合．     

Tidally incised valleys on tropical carbonate shelves: An example from the northern Great Barrier Reef, Australia

The formation of incised valleys on continental shelves is generally attributed to fluvial erosion under low sea level conditions. However, there are exceptions. A multibeam sonar survey at the northern end of Australia's Great Barrier Reef, adjacent to the southern edge of the Gulf of Papua, mapped a shelf valley system up to 220 m deep that extends for more than 90 km across the continental shelf. This is the deepest shelf valley yet found in the Great Barrier Reef and is well below the maximum depth of fluvial incision that could have occurred under a − 120 m, eustatic sea level low-stand, as what occurred on this margin during the last ice age. These valleys appear to have formed by a combination of reef growth and tidal current scour, probably in relation to a sea level at around 30–50 m below its present position.

Tidally incised depressions in the valley floor exhibit closed bathymetric contours at both ends. Valley floor sediments are mainly calcareous muddy, gravelly sand on the middle shelf, giving way to well-sorted, gravely sand containing a large relict fraction on the outer shelf. The valley extends between broad platform reefs and framework coral growth, which accumulated through the late Quaternary, coincides with tidal current scour to produce steep-sided (locally vertical) valley walls. The deepest segments of the valley were probably the sites of lakes during the last ice age, when Torres Strait formed an emergent land-bridge between Australia and Papua New Guinea. Numerical modeling predicts that the strongest tidal currents occur over the deepest, outer-shelf segment of the valley when sea level is about 40–50 m below its present position. These results are consistent with a Pleistocene age and relict origin of the valley.

Based on these observations, we propose a new conceptual model for the formation of tidally incised shelf valleys. Tidal erosion on meso- to macro-tidal, rimmed carbonate shelves is enhanced during sea level rise and fall when a tidal, hydraulic pressure gradient is established between the shelf-lagoon and the adjacent ocean basin. Tidal flows attain a maximum, and channel incision is greatest, when a large hydraulic pressure gradient coincides with small channel cross sections. Our tidal-incision model may explain the observation of other workers, that sediment is exported from the Great Barrier Reef shelf to the adjacent ocean basins during intermediate (rather than last glacial maximum) low-stand, sea level positions. The model may apply to other rimmed shelves, both modern and ancient.     

Red Tide Frequency Analysis Using the Extreme Value Theory

In recent years, the red tide erupted frequently, and caused a great economic loss. At present, most literatures emphasize the academic research on the growth mechanism of red tide alga. In order to find out the characters of red tide in detail and improve the precision of forecast, this paper gives some new approaches to dealing with the red tide. By the extreme values, we deal with the red tide frequency analysis and get the estimation of T-times red tide level U （T） , which is the level once the consistence of red tide alga exceeds on the average in a period of T times.     

萼花臂尾轮虫(Brachionus calyciflorus)COI基因序列变异及种群遗传结构分析

利用线粒体细胞色素氧化酶亚基Ⅰ(cytochrome oxidaseⅠ，COI)基因序列对北京地区和江汉湖群部分湖泊萼花臂尾轮虫(Brachionus calyciflorus)种群遗传结构进行了初步分析。以特异引物进行PCR扩增，获得了661bp的基因片断序列，所得序列与Genbank中B．calyciflorus COI序列的同源性为82％—93％。在6个种群中，共获得了15种单元型。序列分析结果表明，不同季节单元型之间的遗传距离较大(0．248-0．263)，而在同一季节单元型之间遗传距离较小(0．002-0．031)。种群遗传结构分析表明，各种群之间无共享的单元型，同一季节不同湖泊种群之间存在着一定程度的遗传分化，但未按照地理位置形成明显的地理格局。按采样时间分组进行AMOVA分析，组间差异高达94．09％；DH-I与其他种群之间存在着明显的遗传分化。同一湖泊不同季节样品之间，遗传变异较大，这表明在同一湖泊存在着不同基因型的轮虫休眠卵，当环境条件发生了变化后，不同基因型之间会发生更迭。