四倍体太平洋牡蛎(Crassostrea gigas Thunberg)自群繁殖的研究

2004年7~8月,利用诱导的1龄四倍体太平洋牡蛎做亲本,通过解剖取卵、人工受精的方法进行四倍体的自群繁殖。结果表明四倍体太平洋牡蛎自群繁殖的受精率为95.54%,孵化率为37.38%,采用同一雌体四倍体牡蛎与二倍体雄贝杂交产生的三倍体组(TD)的受精率为85.19%,孵化率为99.9%,而以二倍体做母本、四倍体做父本的杂交组(DT)的受精率为98.73%,孵化率为87.63%,二倍体对照组的受精率为96.39%,孵化率为99.9%。四倍体牡蛎经自群繁殖培育出稚贝1130粒。经流式细胞仪分析,四倍体太平洋牡蛎幼虫和稚贝的四倍体率均达到100%。幼虫培育过程中,从孵化出D-形幼虫到出现眼点,幼虫的成活率达11.86%,眼点幼虫的变态率高达16.1%。实验证明四倍体太平洋牡蛎可以进行自群繁殖,比诱导的方法简单高效。     

利用四倍体与二倍体杂交规模化培育全三倍体太平洋牡蛎苗种

利用引进美国的四倍体太平洋牡蛎(Crassostrea gigas)雄贝与我国的二倍体雌贝杂交，规模化培育全三倍体牡蛎苗种。杂交组的平均受精率为48．27％，对照组为80．53％，杂交组较低的受精率可能与四倍体雄贝的精子活力及精子数量有关。杂交组的孵化率、幼虫成活率和变态率分别为81．10％，42．3％和1．82％，对照组分别为79．96％，37．0％和1.80％。杂交组共培育出稚贝1200万粒。不同时期取样的流式细胞仪分析结果表明，杂交组的三倍体率为100％。     

长牡蛎四倍体诱导的研究

本文采用长牡蛎三倍体卵子与二倍体精子授精,用0.5mg/dm3CB处理受精卵抑制第一极体排放诱导出四倍体.处理组在担轮幼虫期检测染色体,4个处理组的四倍体分别为13.95%、12.19%、0%和40.00%.处理组3染色体数在24、25条.其中处理组1、3、4获得稚贝(1～3mm),存活率分别为0.49×10-5、212×10-5和23×10-5.处理组1获得稚贝108粒,处理组3获得附着稚贝7万粒,处理组4获得附着稚贝7000粒.文中还就三倍体雌贝怀卵量及四倍体诱导机制进行了讨论.     

非整倍体太平洋牡蛎的存活、生长与性腺发育

在二倍体与四倍体杂交产生的三倍体牡蛎群中检测到了非整倍体 ,其中 3n± 1非整倍体相对于三倍体的存活率为 6 0 .98%。非整倍体牡蛎作为一个群体 ,其生长与其三倍体同胞在体重上无明显差异 ,且与三倍体一样明显大于其二倍体对照组。非整倍体牡蛎的性腺发育情况与三倍体个体相当 ,也能产生成熟的生殖细胞     

单体全三倍体太平洋牡蛎育苗技术的研究

本文利用四倍体太平洋牡蛎雄贝与二倍体雌贝杂交生产出的全三倍体牡蛎,幼虫经常规方法培育至60%出现眼点幼虫时,投放聚乙烯塑料纸、废旧筛绢网和聚乙烯波纹板作附着基,经过附着变态后,当达到2～3 mm时,可脱基生产单体牡蛎,也可中间培育至10 mm边脱基边出售到养殖单位进行养殖,采用此法生产的单体牡蛎方法简便,成本低,脱基致残率极低,是一种生产单体牡蛎好方法之一.2005-2006年在50m3水体中生产单体牡蛎1000万粒 (1cm),单位水体出苗量为20万粒/m3.     

利用细胞松弛素B抑制第一极体排放诱导近江牡蛎(Crassostrea rivularis)四倍体

采用细胞松弛素B（CB）处理受精卵,抑制第一极体的排放,对近江牡蛎四倍体的诱导和培育进行了研究.结果表明,近江牡蛎在25-28℃时受精卵发育同步性较高.在28℃条件下,CB适宜处理剂量为0.6mg/L.在个别受精卵出现第一极体时实施处理,至对照组的第一极体出现率达到50%终止处理,四倍体的诱导效果较好.5个处理组D形幼虫的平均孵化率为11.0%,显著低于对照组72.4%的平均孵化率.在受精后4-12d期间处理组幼虫的存活率显著低于对照组.处理组胚胎和D形幼虫阶段四倍体的平均比例分别为41.8%和37.9%.四倍体的比例随着幼虫的生长发育呈下降趋势,至受精后12d在各处理组已检测不到四倍体.2组幼虫完成附着变态,从受精卵至稚贝的累计存活率平均为0.3%.本研究结果表明,使用CB处理抑制受精卵第一极体的释放可以有效诱导近江牡蛎四倍体,但所获得的四倍体幼虫存活力差,需要在未来的研究中解决.     

太平洋牡蛎杂交三倍体与诱导三倍体的生长比较

本文以中国太平洋牡蛎二倍体自交作为对照,比较了诱导三倍体群体及其杂交三倍体的早期表型性状。通过对各试验组卵径、卵裂率、D幼率、D形幼虫大小、生长、存活率和倍性等指标进行测定,进一步评估了2种诱导方法的有效性。结果表明:与诱导三倍体群体相比,杂交三倍体表现出明显优势,D幼率、D形幼虫大小均大于诱导三倍体群体,且差异显著(P<0.05);稚贝期壳长和壳高生长也显著快于诱导三倍体群体(P<0.05)。至附着,杂交三倍体的存活率很高,显著优于诱导三倍体群体。就三倍体率而言,杂交三倍体达到100%,而诱导三倍体群体仅为51.00%±11.79%。由上得知,杂交三倍体更适合应用于大规模生产。     

太平洋牡蛎杂交三倍体与诱导三倍体的生长比较

本文以中国太平洋牡蛎二倍体自交作为对照,比较了诱导三倍体群体及其杂交三倍体的早期表型性状.通过对各试验组卵径、卵裂率、D幼率、D形幼虫大小、生长、存活率和倍性等指标进行测定,进一步评估了2种诱导方法的有效性.结果表明:与诱导三倍体群体相比,杂交三倍体表现出明显优势,D幼率、D形幼虫大小均大于诱导三倍体群体,且差异显著(P＜0.05);稚贝期壳长和壳高生长也显著快于诱导三倍体群体(P＜0.05).至附着,杂交三倍体的存活率很高,显著优于诱导三倍体群体.就三倍体率而言,杂交三倍体达到100％,而诱导三倍体群体仅为51.00％士11.79％.由上得知,杂交三倍体更适合应用于大规模生产.     

长牡蛎中国群体与日本群体杂交子一代的生长和存活比较

以中国长牡蛎(C)和日本长牡蛎(J)为材料,进行了4个组合的杂交和自交实验,分析了各实验组受精率、孵化率,幼虫和稚贝的生长、存活以及杂交子代的杂种优势。结果表明,自交组的受精率介于杂交组之间,但是经单因素方差分析表明没有显著性差异; JJ组的孵化率最高,其次是JC和CC组, CJ组的孵化率最低,相同卵子来源的组合在孵化率上无显著差异。JJ组在幼虫期和稚贝期、养成期的壳高、壳长平均值均大于其他三组; JC组在幼虫期和稚贝期、养成期的壳高、壳长仅次于JJ组,其壳高、壳长和存活率杂种优势率均较为明显; CJ组的杂种优势率在幼虫期和稚贝养成期的各个生长性状上都表现为负值。杂交子一代中存在正交和反交结果不同的现象可能与母性效应、遗传因素和环境等因素有关。     

黄河三角洲近江牡蛎规模化苗种繁育技术研究

本研究以黄河三角洲近江牡蛎(Crassostrea ariakensis)为材料,从亲贝性腺促熟培养条件和幼虫培育的盐度、密度、附着基等方面对近江牡蛎规模化苗种繁育技术进行探索,开展近江牡蛎苗种规模化人工繁育。研究发现:采用升温促熟的方式进行黄河三角洲近江牡蛎亲贝促熟培养,经过40 d室内培育,性腺发育成熟;以阴干-升温水刺激方式产卵排精,亲贝精卵排放率达到80%以上;盐度20时,近江牡蛎的受精率、卵裂率和孵化率均最高,达到(96.96±1.91)%、(95.93±1.97)%和(95.87±0.92)%,幼虫生长速度最快,存活率最高且显著高于25和30盐度组(P0.05);与初始密度为10 ind/mL相比,初始密度为6和3 ind/mL时幼虫的生长速度和存活率均较高;牡蛎壳稚贝比扇贝壳稚贝的附着密度稍高,但差异不显著(P0.05)。通过幼虫培育,共获得近江牡蛎稚贝1.98亿粒;平均每个培育池附着基12万片,出苗650万粒;单位水体出苗量达到32.5×10~4粒/m~3,达到规模化苗种生产的要求。     

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,     

Evaluation of the Risk of Marine Slope Instability: A Pseudo-3D Approach for Application to Large Areas

This article presents a methodology developed to evaluate the instability of submarine slopes that extend over a large area. Special attention was paid to (1) the complex geometry (bathymetry) and the expanse of the slope, (2) the heterogeneity of the sediment, and (3) the distribution of the pore pressure. The safety factor was considered as a spatially varying quantity. The General Formulation (GLE, Fredlund and Krahn 1977), which fully satisfies equilibrium conditions, was used for evaluating the stability of the marine slope. The submarine slope failure, which occurred on 16 October 1979 during the construction of the new Nice airport, was studied in order to test the developed model. Geotechnical parameters were taken from experimental tests carried out by IFREMER on 19 cores extracted at different depths (from 27 m to 1300 m) (Cochonat, Bourillet, and Savoye, 1993; Mulder et al., 1994). Many scenarios were proposed in order to explain the cause of the Nice slope failure (Habib, 1994). In this article, two of those scenarios were tested. Simulation results are presented and discussed.