犬齿牙鲆胚胎及仔、稚、幼鱼形态发育观察

犬齿牙鲆(Paralichthys dentatus)卵为端黄卵,受精卵浮性,卵径950~1100μm,油球径200~225μm.在水温20.5~22.0℃,盐度33条件下培育,受精后1 h 20 min 进入卵裂期,6 h 10 min 进入囊胚期,11 h 20 min 进入原肠胚期,19 h 10 min 发育到胚孔封闭期,胚体形成,26 h 50 min 尾芽出现,33 h 35 min心跳开始,48 h 10 min 开始孵化出仔鱼.初孵仔鱼平均全长2.59 mm±0.02 mm,在培育水温为17.0~21.0℃,盐度24~34条件下,胚后发育时序为:1日龄~9日龄为仔鱼前期,10日龄平均全长5.52 mm±0.05 mm,卵黄囊和油球完全吸收进入仔鱼后期;40日龄平均全长20.82 mm±0.67 mm,各鳍鳍条发育形成进入稚鱼期;65日龄平均全长41.13 mm±0.88 mm,全身鳞被完整进入幼鱼早期     

牙鲆性腺分化的组织学研究

运用组织学方法对牙鲆(Paralichthys olivaceus)的性腺分化和发育过程进行了观察.结果表明,牙鲆的性腺发育可分为3个阶段,即原始性腺阶段、性腺分化阶段和性腺分化后阶段.培育水温为18℃～20℃下,孵化后第45天、平均全长为22.0 mm±2.8 mm的牙鲆,其性腺分化尚未开始,属于原始性腺.70日龄、平均全长为38.0 mm±1.7 mm的牙鲆,部分个体中观察到卵巢的雏形,其余个体中性腺变化并不大;到了第110天、平均全长达到86.5 mm±5.9 mm时,雌性个体卵巢的卵巢腔进一步增大,并出现卵原细胞向卵母细胞的转变.精巢的分化开始于90日龄、平均全长为63.5 mm±3.4 mm的幼鱼,此期精原细胞快速增殖,体细胞进行有丝分裂并逐渐形成输精管原基;进一步的细胞学分化则出现在100日龄、平均全长为76.0 mm±8.6 mm的个体中,此时可以看到精小叶的形成;在平均全长为140.0 mm±15.2 mm时,精巢中出现初级精母细胞,标志着性腺分化的基本完成.     

星斑川鲽仔、稚、幼鱼的形态发育与生长

为了摸清星斑川鲽仔、稚、幼鱼各期形态发育特征,2006年4-7月在实验室利用显微数码摄像系统,通过电脑显示屏观察、测量、拍摄记录星斑川鲽胚后发育形态变化.培育水温14.0～19.5 ℃,S 27～31,光照度500 lx左右,饵料依次为经过强化的轮虫、卤虫无节幼体和配合饲料.星斑川鲽初孵仔鱼全长1.80～2.08 mm, 1日龄仔鱼平均全长2.89 mm;3日龄开始摄食;5日龄卵黄囊吸收完毕进入后仔鱼期;15～16日龄全长8.84 mm,开始伏底变态进入稚鱼期;20日龄全长10.12 mm,稚鱼右眼完全迁移至左侧,变态完成营底栖生活进入幼鱼期.星斑川鲽仔鱼变态发生日龄与培育水温有关,在12～15 ℃需24～27 d;15～16 ℃需18～20 d;17～19 ℃需15 d.开始变态仔鱼全长9 mm,变态完成时全长11 mm.幼鱼期鳞被形成,基本具有成鱼的外部形态和习性.     

基于耳石微结构的西北太平洋秋刀鱼(Cololabis saira)年龄与生长研究

根据2014年6月和10-11月在西北太平洋公海采集的168尾秋刀鱼样本,基于耳石微结构并结合基础生物学数据,鉴定了秋刀鱼的日龄,推算了孵化日期,并建立了生长模型和生长率。研究发现:耳石微结构从核心到透明区边缘,轮纹宽度由宽至窄,亮度由暗至明,标记轮多分布在透明区。日龄范围为204~549 d,优势日龄组为231~290 d和381~470 d,日龄最小个体体长207 mm,体质量39 g,日龄最大个体体长291 mm,体质量131 g。孵化日期为2012年12月至2014年4月,孵化高峰期出现在1-3月和8-10月,初步推算秋刀鱼主要分为春生群和秋生群产卵群体。体长和体质量生长模型符合Logistic生长模型。体长平均绝对生长率和相对生长率别为0.224 mm/d和0.000 88,绝对生长率随着日龄增加而减小。体质量平均绝对生长率和相对生长率别为0.293 g/d和0.003 25,最大绝对生长率（0.504 mm/d）和最大相对生长率（0.004 86）出现在351~400 d。     

鲤科经济鱼类马口鱼(Opsariichthys bidens)胚胎发育及仔稚鱼形态与生长观察研究

为了解鲤科经济鱼类马口鱼(Opsariichthys bidens)胚胎及仔稚鱼发育特点,采用人工干法授精获得受精卵,在人工孵化及培育条件下观察了马口鱼胚胎发育及仔稚鱼的形态变化与生长特性。马口鱼成熟卵及受精卵均呈圆形、沉性,卵径分别为1.00—1.20mm及1.4—1.6mm。在26—28oC水温下,胚胎发育历时37h,历经了胚盘形成期、卵裂期、囊胚期、原肠胚期、神经胚期、器官发生期、心跳期和孵出期等阶段,所需积温为968.95oC·h。初孵仔鱼全长3.74±0.04mm。在26—28oC水温下,仔鱼孵后12h,胸鳍原基形成;孵后48h,肠道形成;孵后84h,一鳔室形成;孵后96h,多数开始平游;孵后108h,卵黄囊消失,早期仔鱼发育至后期仔鱼,营外源性营养;孵后14d,两鳔室形成;孵后17d,全长12.46±0.76mm,各鳍发育完整,鳞片开始出现,进入稚鱼期;孵后23d,全长达17.09±1.08mm,外部形态特征与成鱼相近。马口鱼仔稚鱼生长方程显示异速生长特性。本研究积累了马口鱼早期生活史资料,为马口鱼人工繁殖及鱼苗培育提供理论参考。     

已烯雌酚诱导黑鲷幼鱼性转换

黑鲷Sparusmacrocephalus是雌、雄同体,雄性先成熟鱼类。在人工养殖条件下,2龄鱼全为雄性,3龄鱼个别转为雌性。本项研究的目的是使用性激素促使黑鲷提前转为雌性,缩短产卵周期。本次实验是使用当年幼鱼,目的在于进一步找出较佳的处理年龄和使用的激素剂量。1　材料与方法1.1　材料实验使用的黑鲷为1994年孵出,至同年11月16日实验开始时,鱼龄为6个月。这批实验用鱼取35尾测量,全长范围为155～185mm,平均169mm;体长131～154mm,平均139mm;体重67～112g,平均94g。其中10尾鱼取性腺做组织切片观察,有60%已分化出卵巢和精巢,其余未分化。1.2　方…     

条石鲷消化道发育的组织学观察

对人工养殖的条石鲷（Oplegnathus fasciatus）仔、幼稚鱼消化道及消化腺的发育过程进行了系统的组织学观察。研究表明： 初孵仔鱼 （体长1.66～2.20 mm）的消化道完全处于未分化状态。1 日龄仔鱼全长1.83～2.32 mm, 消化道中部开始形成空腔, 为初始的消化道腔。2 日龄仔鱼全长2.61～2...     

虎斑乌贼( Sepia pharaonis )胚胎发育及孵化历期观察

采捕虎斑乌贼野生卵群进行室内培育,采用显微成像系统,观察其胚胎发育过程,并详细描述各发育期的特征。结果显示:虎斑乌贼卵长径(30.7±2.4)mm,短径(13.4±1.3)mm,胚胎发育过程共分为卵裂、囊胚期、原肠期、器官芽原基出现、眼色由无色到黑色等30期,探讨了主要器官(眼、漏斗等)的发生变化过程。在胚体生长期间,胚体长度随时间逐渐增加,而卵黄大小则随之减小。从7—20d,胚体长度由2.5mm增至11.3mm,而卵黄直径由8.9mm减至4.5mm,胚体与卵黄长度比例由0.28增至2.51。在水温(23±0.5)℃,盐度28,pH7.41条件下,孵化高峰期为20—24d,孵化率为85.3%,初孵乌贼幼体平均体长(13.5±0.3)mm,平均胴体长(8.6±0.3)mm,平均体重(0.18±0.02)g。     

漠斑牙鲆仔、稚、幼鱼的形态发育研究

2006年12月至2007年2月,在福建省漳州市东山县华涛水产综合养殖场,对漠斑牙鲆(Paralichthys lethostigma)仔、稚、幼鱼各发育阶段的形态特征进行了观察和描述.初孵仔鱼平均全长2.73±0.211mm.在培育水温18.1～23.0℃和盐度为33～34条件下,初孵仔鱼至孵化后7日龄为前期仔鱼,6日龄仔鱼开口;孵化后8日龄至30日龄为后期仔鱼;孵化后31日龄至45日龄为稚鱼期;孵化后46日龄进入幼鱼期.冠状幼鳍的消长、右眼的移位以及体色的左右不对称是漠斑牙鲆早期发育过程中最明显的外部形态变化.     

犬齿牙鲆早期形态特征和生长、发育规律

为掌握犬齿牙鲆早期发育的规律,2006年3-6月在实验室利用显微数码摄像系统,通过电脑观察、测定、拍摄犬齿牙鲆仔、稚、幼鱼各期的发育时间及早期的形态特征.犬齿牙鲆室内人工育苗的培育水温19～21 ℃,S为30,pH为8.2,光照度为500 lx左右,饵料依次为经过强化的轮虫、卤虫无节幼体和配合饲料.初孵仔鱼全长2.2～2.5 mm,身体透明,至4～5日龄,卵黄囊缩小,开始摄食,6～7日龄卵黄囊吸收完毕进入后仔鱼期;至29日龄全长9.0～9.4 mm,冠状幼鳍形成完善,开始进入稚鱼期;43日龄时全长15.0～16.0 mm稚鱼右眼完全迁移至左侧,变态完成,营底栖生活进入幼鱼期;幼鱼期鳞被形成完整,基本具有成鱼的外部形态和生活习性.     

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.     

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。     

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.     

Phylogenetic diversity and phenotypic characterization of cultivable bacterioplankton isolated from polar oceans

A set of 27 marine planktonic bacteria isolated from the polar regions was characterized by 16S rDNA sequencing and physiological and biochemical testing. More than half of these bacteria were positive for caseinase, gelatinase and 13-glucosidase, and could utilize glucose, maltose or malic acid as carbon source for cell growth. Twelve isolates expressed nitrate reduction activities. Except for one antarctic isolate BSwlO175 belonging to Actinobacteria phylum, these isolates were classified as γ-Proteobacteria, suggesting that γ-Proteobacteria dominated in cultivable marine bacterioplankton at both poles. Genus Pseudoalteromonas was the predominant group in the Chukchi Sea and the Bering Sea, and genus ShewaneUa dominated in cultivable bacterioplankton in the Prydz Bay. With sequence similarities above 97%, genus Psychrobacter was found at both poles. These 27 isolates were psychrotolerant, and significant 16S rDNA sequence similarities were found not only between arctic and antarctic marine bacteria （ 〉 99% ）, but also between polar marine bacteria and bacteria from other aquatic environments （ ≥ 98.8% ）, including temperate ocean, deep sea, pond and lake, suggesting that in the polar oceans less temperature-sensitive bacteria may be cosmopolitan and have a bipolar, even global, distribution at the species level.     

Deep-Sea Sediment Compression Curves: Some Controlling Factors, Spurious Overconsolidation, Predictions, and Geophysical Reproduction

Oedometer tests have been carried out on 70 undisturbed surficial clays (at approximately 250 mm below the mudline), mostly collected by free-fall corers from sites widely scattered throughout the deep-sea North Atlantic. Acoustic measurements were also made, initially on contiguous samples and ultimately on the same sample using a geophysically instrumented oedometer which also collected electrical resistivity data. Apart from those quiescent areas below the carbonate compensation depth, such as north of the West Indies where very fine clays exist, most of the samples are silty clays whose geotechnical-geophysical properties are dependent on the type of clay minerals present (and their ability to take in moisture), the sand-size fraction, and the quantity of carbonate present. Thus the pure clays have high compressibilities which decrease on the addition of coarse particles, while the converse is true for the acoustic parameters, these increasing with the sand fraction. Using the notion of the intrinsic compression line for all samples, and comparison to it of the measured compression curves, it is clear that, contrary to some previously held ideas, most deep-sea clays are normally consolidated; the addition of carbonate has the effect of creating an open, stronger sediment skeleton. Interestingly, where information is available, the variation with depth of a sample's acoustic velocity follows the void ratio pressure relationship of the compression curve. This allows the construction of an in-situ sediment compression curve using the in-situ geophysical observations.     

INFORMATION FOR AUTHORS

<正>Acta Oceanologica Sinica(AOS)is a comprehensive academic journal edited by the Editorial Committee of Acta Oceanologica Sinica and is designed to provide a forum for important research papers of the marine scientific community which reflect the information on a worldwide basis.The journal publishes scholarly papers on marine science and technology,including physics,chemistry,biology,     

Estimation of Sediment Properties during Benthic Impact Experiments

Sediment properties, such as water content and density, have been used to estimate the dry and wet weights, as well as the volume of sediment recovered and discharged, during benthic impact experiments conducted in the Pacific and Indian Oceans. The estimates show that the weights of dry (355-1332 t) and wet sediment (1651-4888 t) recovered during the experiments, are not only a function of the total duration and distance covered during the experiment, but also depend on water content and density of the sediment. Estimation of dry sediment and its volumetric ratio in the discharge, are key parameters for calculating the discharged volume. The estimated volume of wet sediment recovered (1427-4049 m 3 ) as well as discharged (2693-6951 m 3 ) during the experiments, provide important inputs to evaluate the sediment resettlement and migration. Using these estimates, the average depth of excavation on the seafloor, can also been calculated. However, the stages of sediment recovery and discharge are expressed differently in some of the experiments. In order to standardize these, different stages have been identified, and definitions of certain terms have been suggested, for use in the future. The methods of calculating different properties, as well as weight and volume of discharged sediment are described in the paper for use in other applications concerning deep-sea discharges.