库页岛厚蛤蜊的人工繁殖和胚胎发育

通过亲贝促熟、人工催产、幼体培育和采苗等技术环节,初步建立了库页岛厚蛤蜊（Pseudocardium sachalinense）的人工繁育技术。对库页岛厚蛤蜊胚胎发育过程的观察表明,在水温22～24℃,盐度28～30条件下,受精卵经约50min开始卵裂;约20h发育至D形幼体;经约11d的人工培育,幼体出现足和水管原基...     

(鱼免)状黄姑鱼早期发育特征及对温盐度的适应性

1996年3~6月采用人工注射LRH-A和HCG诱导状黄姑鱼自然产卵受精,观察6批次胚胎发育的结构特征和1~16日龄仔鱼形态变化及温度、盐度对状黄姑鱼早期发育和存活的影响,为状黄姑鱼大规模人工繁殖和苗种培育提供科学依据。根据其外部形态和胚胎行为的出现将状黄姑鱼胚胎发育划分为17期,3日龄开口;状黄姑鱼受精卵孵化的温度范围为16.3~30℃,最适孵化温度为22~24℃;孵化盐度范围为13.7~53,最适孵化盐度范围为26.9~40.7,其中盐度为7.2时受精卵无法孵化,盐度在40.7以上的受精卵全部为浮性,盐度为26.9以下全部呈沉性;状黄姑鱼仔鱼存活的适合盐度为20.2~33.4,随着仔鱼的生长,对耐盐的适应性也逐渐增强。     

水温和盐度对长牡蛎“海大1号”早期生长发育的影响

为确定长牡蛎新品种"海大1号"苗种繁育的最适环境条件,研究了盐度对其胚胎发育的影响以及盐度、水温对其幼虫生长、存活率和附着率的影响。结果表明:长牡蛎"海大1号"受精卵孵化的最适盐度为30~35,孵化率最高可达90%。幼虫生长的适宜盐度为20~35,最适盐度为20~30;存活的适宜盐度为20~35,最适盐度为20~25;幼虫附着的适宜盐度为20~35,最适盐度为25~30;对长牡蛎"海大1号"幼虫生长、存活、附着的适宜水温分别为为20~30℃、20~25℃、20~30℃,最适水温分别为30、25、30℃,高温35℃时幼虫全部死亡。综上,长牡蛎"海大1号"苗种培育的适宜盐度为20~35,适宜水温为20~25℃。上述结果为长牡蛎"海大1号"规模化苗种繁育提供了重要的基础资料。     

点带石斑鱼亲鱼培育、产卵和孵化的试验研究

采用经埋植外源激光法诱导所得的点带石斑鱼功能性雄鱼和人工养殖的雌鱼进行亲鱼培育、产卵和孵化的试验研究，在1999-2000年的两年中，繁殖仔鱼7103万尾，结果表明，雌鱼的绝对生死力为535.01万粒卵，相对生殖力为810.21粒/g体重，水泥池中培育的点带石斑鱼能自然产卵与水温相关，水温高于24℃时，产卵呈一定的周期性，即连续产卵5-7天，停产数天后再开始下一个产卵周期；水温低于24℃时，产卵受到抑制，水温对胚胎发育有明显的影响，水温25.5-28.5℃胚胎发育时间为21h53min，仔鱼活力好，盐度为30-33时，胚胎发育正常盐度降低造成孵化率下降。     

硬壳蛤(Mercenaria mercenaria)繁殖生物学研究

采用组织学和实验生态学方法对浙江引种养殖的硬壳蛤的性腺发育、生殖周期、胚胎发育、幼虫和稚贝培育进行了研究.结果表明,浙江养殖的硬壳蛤性腺发育过程以1年为1个周期,可分为增殖期、生长期、成熟期、排放期、休止期5个阶段;繁殖期在4月下旬至6月下旬,水温19.0-28.2℃,可大批产卵二次;肥满度最高为7.11%（6月份）,最低为3.68%（1月份）;水温20-22℃时,D形幼虫孵出时间约为20h,浮游幼虫经9-10天培育进入变态附着期,10-11天发育变态为稚贝.研究还发现,硬壳蛤的精子在光学显微镜下观察呈牛角形或较直的长三角形,与常见的双壳类软体动物的精子形态明显不同.文中还讨论了性腺发育与积温的关系,指出性腺发育成熟的积温和有效积温大约为1800℃和600℃.     

驼背鲈的胚胎发育

对驼背鲈(Cromileptes altivelis)的胚胎发育过程进行了观察,描述其发育各期的形态特征及发育速度。驼背鲈成熟卵呈浮性,透明,平均卵径为810μm,油球一个。在水温25~27℃,盐度30条件下,胚胎发育时间为24 h 10 min。     

双棘黄姑鱼人工育苗技术的研究

对双棘黄姑鱼【Nibeadiacanthus(Lacepede)】催产孵化和育苗技术进行了试验研究,并从形态学方面对其近似种和易混种进行了比较。结果显示,双棘黄姑鱼性腺发育至Ⅳ期经人工催产都能产卵受精．效应时间为20～40h。胚胎发育适宜水温为22～26℃．适宜盐度为30～35,孵化率为80％～90％。在育苗水温27～29℃,盐度28～30,150万初孵仔鱼经20d培育,共育出全长1．4～2．3cm的稚鱼95．3万尾,育成率62．3％;其中32．2万稚鱼分池继续培育至36天,育出全长3．1～5．2cm的幼鱼18．4万尾。本试验说明对双棘黄姑鱼进行人工催产孵化育苗,能够培育出达到商品规格的鱼种。     

山东北部沿海四角蛤蜊性腺发育年周期研究

研究了山东省滨州市无棣县马山子海区四角蛤蜊的繁殖周期及其与环境因子的关系。自2007-04～2008-03,每月采集1次样品,同时,测定采样点的水温、盐度和叶绿素a含量。组织学观察结果表明该地区四角蛤蜊全年只有1个主要的产卵季节:7～9月。配子成熟及排放期间,水温和叶绿素a含量均处于较高水平,可为性腺发育提供能量,也有利于幼虫的存活和生长。从配子发生到成熟,卵径逐渐增大,并在产卵前达到最大,产卵后则降低。雌雄个体在数量上存在显著差异(雌∶雄=1.138∶1,P<0.05),雌性略多于雄性,未发现雌雄同体现象。条件指数(软体部干重/壳干重×100)的研究结果显示该地区四角蛤蜊在配子排放后,11月至次年1月间存在1个明显的恢复期,从最低值3.95(10月)逐渐上升至峰值11.95(次年1月)。     

毛蚶的性腺发育和生殖周期

根据毛蚶性腺的组织学和外部形态特征，可将其性腺发育分为：增殖期、生长期、成熟期、排放期和休止期五个时期。根据肥满度的周年变化规律并结合性腺组织切片的观察结果，认为在连云港海区的毛蚶性腺发育为一年一个周期，排放期为7月至9月，繁殖盛期在7月中旬至8月中旬。毛蚶为分批产卵类型，集中排放需要满足一定的水温、盐度等理化因子的刺激。雌、雄性腺发育基本同步，雄性发育略快，雌雄比为1．2：1。     

温度和盐度对蒙古裸腹溞发育的影响

利用１９８２年采自晋南硝池的蒙古裸腹溞,进行室内培养和观察,研究温度和盐度对其胚胎发育的影响。结果表明：蒙古裸腹溞在２０－３３℃温度和在５－４０盐度条件下的胚胎发育时间为３８－９７ｈ,胚后发育存在３个幼龄和４－９个成龄,幼龄的龄期均短于成龄;在２０－３０℃范围内,随温度升高蒙古裸腹溞的胚胎发育时间趋短,幼龄和成龄的龄期以及溞的寿命和最大体长明显降低,３０℃后升温对溞发育的影响明显减弱;５－４０的盐度对蒙古裸腹溞的胚胎发育时间、胚后发育的龄数和龄期影响均不显著,但该溞在５－１０盐度下寿命较长,个体也较大。上述结果显示蒙古裸腹溞发育的最适温度和盐度分别为２８℃和１０,并且该溞的胚后发育时间相对较西班牙盐水裸腹溞短。     

Microbial Biomass and Organic Nutrients in the Deep-Sea Sediments of the Central Indian Ocean Basin

In order to assess the impact of deep-sea mining on the in situ benthic life, we measured the microbial standing stock and concentration of organic nutrients in the deep-sea sediments of the Central Indian Ocean Basin in the Indian pioneer area. Sediments were collected using box core and grab samples during September 1996. The total bacterial numbers ranged from 10 10 -10 11 cells per g -1 dry weight sediment. There was a marginal decrease in the number of bacteria from surface to 30 cm depth, though the subsurface section registered a higher number than did the surface. The highest numbers were encountered at depths of 4-8 cm. The retrievable number of bacteria were two orders less in comparison with the direct total counts of bacteria. An almost homogeneous distribution of bacteria, total organic carbon, living biomass, and lipids throughout the depth of cores indicates active microbial and benthic processes in the deep sea sediments. On the other hand, a uniform distribution of total counts of bacteria, carbohydrates, and total organic carbon in all the cores indicates their stable nature and suggests that they can serve as useful parameters for long-term monitoring of the area after the benthic disturbance. Further studies on temporal variability in this region would not only verify the observed norms of distribution of these variables but would also help to understand restabilization processes after the simulated benthic disturbance.     

A Review of Some Environmental Issues Affecting Marine Mining

This article reviews information recently available from existing marine and coastal mining for responses to environmental issues affecting marine mining at different depths. It is particularly but not exclusively concerned with those issues affecting seabed biodiversity impact and recovery. Much information has been gathered in the past 10 years from shallow mining operations for construction aggregate, diamonds, and gold, from coastal mines discharging tailings to shallow and deep water, and from experimental deep mining tests. The responses to issues identified are summarized in a series of eight tables intended to facilitate site-specific consideration. Since impacts can spread widely in the surface mixing layer SML, and can affect the biologically productive euphotic zone, the main issues considered arise from the depth of mining relative to the SML of the sea. Where mining is below the SML, the issue is whether it is environmentally better to bring the extraction products to the surface vessel for processing (and waste discharge), or to process the extraction products as much as possible on the seabed. Responses to the issues need to be sitespecific, and dependent on adequate preoperational environmental impact and recovery prediction. For deep tailings disposal from a surface vessel, there are four important environmental unknowns: (1) the possible growth of "marine snow" (bacterial flocs) utilizing the enormous quantities of fine tailings particles (hundreds or thousands of metric tons per day) as nuclei for growth, (2) the possibility that local keystone plankton and nekton species may migrate diurnally down to and beyond the depth of deep discharge and hence be subjected to tailings impact at depth, (3) the burrow-up capability of deep benthos and their ability to survive high rates of tailings deposition, and (4) the pattern and rate of dispersion of a tailings density current through the deep water column from discharge point to seabed. Actions to obtain relevant information in general and site-specifically are suggested.     

Increased Particle Fluxes at the INDEX Site Attributable to Simulated Benthic Disturbance

Particle fluxes were measured 7 m above the sea bottom during the predisturbance, disturbance, and postdisturbance periods by using time series sediment traps attached to seven deep-sea moorings deployed in the INDEX experiment site in the Central Indian Basin. The predisturbance particle fluxes varied between 22.3 to 55.1 mg m -2 day -1 . Increased and variable particle fluxes were recorded by the sediment traps during the disturbance period. The increase observed was 0.5 to 4 times more than the background predisturbance fluxes. The increases in particle fluxes (~4 times) recorded by the sediment trap located in the southwestern direction (DMS-1) were the greatest, which could be the result of preferential movement of resuspended particles generated during the deep-sea benthic disturbance along the general current direction prevailing in this area during the experimental period. Also, the traps located closer to the disturbance area recorded greater fluxes than did the traps far away, across the Deep Sea Sediment Resuspension System path. This variability in recorded particle fluxes by the traps around the disturbance area clearly indicates that physical characteristics such as grain size and density of the resuspended particles produced during the disturbance had an important effect on particle movement. The postdisturbance measurements during ~5 days showed a reduction in particle fluxes of ~50%, indicating rapid particle settlement.     

Assessing the Validity of Seismo-Acoustic Predictor Equations for Obtaining Seabed and Sub-Surface Sediment Physical Properties

The interdependence between the seismo-acoustic properties of a marine sediment and its geotechnical/physical parameters has been known for many years, and it has been postulated that this should allow the extraction of geotechnical information from seismic data. Though in the literature many correlations have been published for the surficial layer, there is a lack of information for greater sediment depths. In this article, a desktop study on a synthetic seafloor model illustrates how the application of published near-surface prediction equations to subsurface sediments (up to several tens of meters burial depth) can lead to spurious predictions. To test this further, acoustic and geotechnical properties were measured on a number of sediment core samples, some of which were subjected to loading in acoustically-equipped consolidation cells (oedometers) to simulate greater burial depth conditions. For low effective pressures (representing small burial depths extending to around 10 meters subsurface), the general applicability of established relationships was confirmed: the prediction of porosity, bulk density, and mean grain size from acoustic velocity and impedance appears generally possible for the investigated sedimentary environments. As effective pressure increases through, the observed relationships deviate more and more from the established ones for the near-surface area. For the samples tested in this study, in some instances increasing pressure even resulted in decreasing velocities. There are several possible explanations for this abnormal behavior, including the presence of gas, overconsolidation, or bimodal grain size distribution. The results indicate that an appropriate depth correction must be introduced into the published prediction equations in order to obtain reliable estimates of physical sediment properties for greater subsurface depths.     

Geoacoustic Inversion via Genetic Algorithm and Its Application to Manganese Sediment Identification

An acoustic inversion method using a wide-band signal and two near field receivers is proposed and applied to multiple layered seabed models including a manganese sediment. The inversion problem can be formulated into a probabilistic model comprised of signals, a forward model, and additive noise. The forward model simulates wide-band signals, such as chirp signals, and is chosen to be the source-waveletconvolution plane wave modeling method. The wavelet matching technique, using weighted least-squares fitting, estimates the sediment sound-speed and thickness on which determination of the possible numerical ranges for a priori uniform distribution is based. The genetic algorithm is applied to a global optimization problem to find a maximum a posteriori solution for determined a priori search space. Here the object function is defined by an L 2 norm of the difference between measured and modeled signals. Not only the marginal pdf but also its statistics are calculated by numerical evaluation of integrals using the samples selected during importance sampling process of the genetic algorithm.     

海上大直径钢管桩打桩过程中桩周土强度弱化研究

海上大直径钢管桩打桩过程中,桩周土体受到强烈扰动而发生强度弱化,掌握桩周土体强度弱化规律对于准确预测打桩过程、保证工程安全具有重要意义。为研究土体强度弱化规律,开展了环剪试验模拟打桩对桩周土体的扰动,测试土体强度随剪切速率的变化规律,建立了描述土体强度弱化规律的拟合公式,引入到打桩分析软件中。研究结果表明：土体的强度折减程度不仅与土体本身的性质有关还受到土体的埋深和剪切速率的影响,埋深越深土体强度折减程度越低,剪切速率越高土体强度折减越高,在打桩分析中可采用这里推荐的线性折减方法来模拟不同深度处土体强度的折减规律。     

Determination of In Situ Sediment Shear Strength from Advanced Piston Corer Pullout Forces

The advanced piston corer (APC) has been used by the Ocean Drilling Program since 1985 for recovering soft sediments from the ocean floor. The pullout force measured on extracting the core barrel from the sediment is shown to correlate with the average shear strength of the sediment core measured in the ship's laboratory. A simple rule of thumb is derived relating the shear strength of the sediment to the pullout force. Multiple APC holes at individual sites allow the consistency of the pullout measurements to be assessed. The effects of different operational procedures during APC coring are also explored. Although generally applicable, the correlation between pullout force and laboratory measurements of shear strength breaks down for some APC holes, possibly because of the disturbance of some sediment types during the APC coring process. A better understanding of the physical process of APC coring, and its effect on the properties of the sediment both inside and immediately outside the core barrel, would indicate what confidence can be put on the measurement of pullout force as a way of evaluating the in situ shear strength of deep sea sediments.     

Interannual Sea Level Variations and Annual Tides in the Northwestern Pacific

Specific properties of the interannual sea level variations and annual tides in the Northwestern Pacific were studied. Several tide stations were monitored. The monthly mean sea level for the year of 1995 was analyzed at each tide station. A seismic event in 1995, some tectonic activity around the subject area, and the Kuroshio (the oceanic western boundary current) may possibly contaminate results which would have occurred from the astronomical annual tide alone.     

《Acta Oceanologica Sinica》Vol. 33(2014) contents

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