长江口夜光藻(Noctiluca scintillans)年间变化和水域富营养化趋势

根据1959年和2002年在长江口海域28°00'—32°00'N,122°00'—123°30'E海域4个季节8个航次海洋调查资料,分析长江口夜光藻丰度的平面分布和季节变化特征。并结合同步的温度资料进行曲线拟合,构造数学模型,计算最适温度。结合夜光藻分布特征、生态类群,比较不同年间夜光藻丰度变化趋势,分析长江口富营养化趋势对夜光藻丰度的影响。结果表明,夜光藻出现率和平均丰度均表现为春季丰度极高而其它季节较低。例如春季长江口夜光藻的最高丰度可以达到48576.00ind/m3,出现率为96.30%。该种在春季有明显的集群性,其它季节聚集强度指标值较低。盐度是影响夜光藻的平面分布的主要因素。长江口夜光藻适温范围较窄。仅仅在15—20℃之间有较高的数量。通过曲线拟合计算,其丰度和温度的函数关系符合YieldDensity模型。进一步通过极值计算得出,夜光藻最适温度为17.53℃。在长江口,夜光藻往往生活在在长江径流和外海水形成的河口锋水域。因而是暖温性近海种。近年来在春季,长江口夜光藻数量明显增多,夜光藻数量的年间变化特征可能与长江口富营养化相关。夜光藻赤潮的爆发就是长江口海域富营养化的结果之一。     

夜光藻配子细胞实时荧光定量PCR检测方法的建立与应用

夜光藻是我国广泛分布的赤潮原因种之一,其有性繁殖在种群增长中的作用尚不明确,定量分析配子细胞是研究夜光藻有性繁殖过程的重要手段。利用实时荧光定量PCR技术,以夜光藻rRNA基因的18S-ITS1为靶区域,建立了定量检测夜光藻配子细胞的方法。以配子细胞基因组DNA和含目的片段的重组质粒分别建立标准工作曲线,二者均呈现良好的线性响应,检出限分别为每反应0.17个细胞和10²个拷贝,满足定量检测应用需求。应用该方法对2015年逐月采集的胶州湾环境样品进行检测,并首次对夜光藻配子细胞的季节变化、水平分布与垂直分布进行了研究。结果表明,调查海域夜光藻配子丰度呈冬末春初、夏季双峰分布,范围为18.12~9.70×10⁵ cells/L;在水深小于10m的湾内近岸站位,配子丰度较低,垂直分布均匀;在湾中心、湾口和湾外的深水站位,配子丰度较高,仅在2~3月、7月和11月出现垂向差异。夜光藻配子细胞对种群增长和存续有潜在的积极意义,其丰度在营养细胞丰度高值期相对较高,在营养细胞丰度极低时仍可普遍检出。丰富了对近岸海域夜光藻配子细胞时空分布的认识,为深入研究夜光藻的种群增长模式、进一步探究其赤潮暴发的内在机理奠定了基础。     

礁区浮游植物群落结构特征及其与环境因子的关系

通过2015年7月(夏季)和10月(秋季)对渤海湾天津海域人工鱼礁区浮游植物2个航次的调查,共鉴定出浮游植物2门10属14种,其中硅藻门(Bacillariophyta)9属12种,甲藻门(Pyrrophyta)1属2种。夏、秋季全区浮游植物密度和种类季节变化明显,夏季细胞丰度(平均值为13.4×10~4cells/m~3)高于秋季细胞丰度(平均值为1.87×10~4cells/m~3)。夏季主要优势种有星脐圆筛藻(Coscinodiscus asteromphalus)、夜光藻(Noctiluca scintillans)、尖刺拟菱形藻(Pseudo-nitzschia pungens)。秋季优势种有星脐圆筛藻、格氏圆筛(Coscinodiscus granii)、夜光藻,其中,星脐圆筛藻是夏、秋季的第一优势种。虽然浮游植物优势种存在明显的季节更替现象,但鱼礁区与对照区的优势种相同。通过冗余分析(RDA)发现,影响天津海域人工鱼礁区浮游植物群落结构的主要环境因子,夏季包括叶绿素、亚硝酸盐;秋季包括水温、亚硝酸盐和磷酸盐。     

日照市近岸夜光藻生消特征及其与水温和营养盐的关联

为摸清日照近岸夜光藻赤潮爆发规律,以有效防控夜光藻赤潮,本研究在日照市近岸海域选择3个监测站点,监测水文气象因子、化学因子和浮游植物。结果显示：日照市海区夜光藻赤潮爆发区多位于近海海区。夜光藻赤潮爆发时间在3—4月份,夜光藻密度南低北高。日照市海区夜光藻属冷水种,6℃开始爆发生长,18℃消亡。三月初夜光藻优势度在0.2～0.3之间,三月中旬到四月初夜光藻优势度逐渐增大,最大达0.99。夜光藻爆发时,无机氮0.2～0.3 mg/L。夜光藻爆发初期活性磷酸盐浓度高于末期,且随着夜光藻密度增加而升高。磷元素是夜光藻爆发的限制因子。夜光藻赤潮过程复杂,受物理、化学、生物、气象等多重因素的综合影响。日照市夜光藻具有冷水性特征。     

夜光藻高效培养方法建立及其有性繁殖发生机制的初步研究

夜光藻(Noctilucascintillans)是典型的赤潮生物,在世界多个海域形成过大面积赤潮,对海洋生态系统构成一定的威胁。夜光藻赤潮的发生不仅受外界环境因子的影响,其有性繁殖的方式在赤潮发生过程中也起着重要作用。本研究从连云港海域分离获得一株夜光藻,利用自行设计的饵料藻投喂装置,以天然海水为培养基,在温度20～25℃范围内实现了夜光藻的室内长期培养,并观察记录了夜光藻配子发生全过程。研究结果表明,夜光藻不同生长阶段培养体系中配子母细胞与营养细胞密度变化趋势基本一致,显示夜光藻的有性繁殖发生与种群丰度存在一定的相关性,但它们之间的因果关系还有待进一步探讨。本研究结果加深了对夜光藻有性繁殖的认识,有助于阐明其种群增长模式,并深入理解其赤潮暴发机制。     

霞浦长表岛附近海域浮游植物群落特征与环境因子分析

为了进一步了解霞浦长表岛附近海域浮游植物群落特征,文章利用2019年5月(春季)、9月(夏季)、12月(秋季)和2020年2月(冬季)4个航次调查的浮游植物和水环境数据,分析了浮游植物群落结构特征,通过冗余性分析(RDA)研究了影响浮游植物群落结构的主要环境因子,结果共鉴定出浮游植物4门60属170种,其中硅藻48属131种,甲藻10属26种,蓝藻1属2种,金藻1属1种。浮游植物以近岸广温广盐种和暖水种为主,全年优势种有13种,春季以东海原甲藻和夜光藻为主,夏季、秋季和冬季以中肋骨条藻和琼氏圆筛藻为主。浮游植物丰度在空间分布上整体呈现近岸高、远岸低、南部低、北部高的趋势特点。RDA和Person相关性分析表明,浮游植物丰度的季节动态变化主要受水温影响;春季和夏季适宜的温度与营养盐促进了浮游植物的大量增长,秋季和冬季则主要受到温度的影响。浮游植物大量繁殖增长甚至暴发出现在春季和夏季,霞浦长表岛海域滨海核电应在春季和夏季重点加强该海域赤潮灾害的监测预警。     

胶州湾夜光藻种群动态及其大量繁殖的生态机制

为研究胶州湾夜光藻大量繁殖的生态机制,于2015年逐月对胶州湾12个站位进行了多学科综合调查,获取了温度、盐度、营养盐等环境因子的周年数据,分析了夜光藻种群丰度和结构的时空分布特征,探讨了环境因子对夜光藻种群动态的影响,以及夜光藻种群增长与其繁殖方式的相关关系。结果发现:全年各站位夜光藻丰度范围为0—31.17×10~3ind./m~3,月平均丰度呈现双峰分布;二分裂个体比例介于0—31.25‰,有性繁殖个体比例介于0—29.41‰,两种繁殖方式均呈现出季节差异及空间差异。相关性分析表明,影响夜光藻种群动态的主要因子包括水温、叶绿素a、硝氮及亚硝氮。夜光藻是冷水种,水温与夜光藻种群丰度、两种繁殖个体比例均呈显著负相关;叶绿素a反映夜光藻食物的丰富程度,与夜光藻丰度、两种繁殖个体比例呈显著正相关;亚硝氮和硝氮可能对夜光藻代谢繁殖起调控作用,与夜光藻丰度及有性繁殖个体比例呈负相关。     

环境DNA分析大亚湾夜光藻藻华对真核浮游生物群落的影响

夜光藻是全球广泛分布的藻华种之一,其摄食作用对浮游生物的群落结构有着重要影响。利用环境DNA技术和Spearman相关性分析,文章研究了2021年1月中旬大亚湾夜光藻高丰度站位浮游生物的群落结构与生物相关性。结果显示,夜光藻高丰度站位的海水温盐条件为温度14.4～18.3℃、盐度32.52‰～33.14‰。夜光藻丰度较高的站位中,卡顿藻科、海链藻科等浮游植物类群的相对丰度均值为2.41%和2.23%,明显高于其他站位的0.75%和0.62%;同时拟哲水蚤科与长腹剑水蚤科等类群的相对丰度均值为8.22%和4.46%,明显低于其他站位的64.13%和11.12%。结合Spearman相关性分析表明,夜光藻丰度增加可能导致其对拟哲水蚤科等类群摄食压力增加,拟哲水蚤科类群丰度减少降低了卡顿藻科、海链藻科、原甲藻科、隐芽藻科等浮游植物类群的摄食压力,使其生物丰度增加;同时夜光藻摄食压力增加使得裸甲藻科、圆筛藻科等浮游植物丰度下降。因此,夜光藻丰度增加影响了水域中真核浮游生物群落结构。综上结果表明,环境DNA技术有助于认识夜光藻在浮游生物群落中的生态地位,可用于浮游生物各类群之间的关系分析。     

渤海浮游病毒的时空分布

利用流式细胞仪对渤海浮游病毒的丰度分布进行了研究。结果表明, 浮游病毒丰度在6.40 ×105—3.59 × 107个/mL之间。辽东湾断面, 浮游病毒丰度春季在西部海域较高, 夏季在中部海域较高, 秋、冬季在东、西部海域均较高; 渤海湾断面, 4 季丰度均在中部海域出现高值区; 莱州湾断面, 夏、秋、冬季均在东部海域出现丰度高值区; 渤海海峡断面, 春、秋、冬季于海峡中部海域丰度较高。垂直分布上, 表层和底层水体浮游病毒丰度在夏季差异性显著, 在其它季节无显著差异。夏季浮游病 毒丰度显著高于其它季节。夏季, 连续站浮游病毒丰度昼夜波动幅度较大, 冬季较平缓。相关性分析表明, 浮游病毒丰度在春、夏、秋季均与温度显著正相关; 夏季与异养细菌丰度、微微型真核浮游植物丰度显著正相关; 秋季与微微型浮游植物丰度显著正相关; 冬季仅与异养细菌丰度显著正相关。     

2004年夏季中国南海北部的浮游植物

报道了2004年夏季南海北部18个大面测站浮游植物的调查结果。应用Utermhl方法初步鉴定出浮游植物4门74属159种,平均细胞丰度为(115.05±438.89)×103个/L(n=91),其中硅藻在物种丰富度和细胞丰度上占绝对优势;其次为甲藻。主要优势种为柔弱伪菱形藻Pseudo-nitzschiadelicatissima、旋链角毛藻Chaetoceroscurvisetus、皇冠角毛藻Chaetocerosdiadema、具齿原甲藻Prorocentrumdentatum和冰河拟星杆藻Asterionellopsisglacialis。调查区浮游植物表层细胞丰度的平面分布从沿岸向外海迅速减少,高值区分布在广东沿岸和珠江口附近海域。同1999年同期资料相比,浮游植物细胞丰度增加1倍,但平面分布趋势相同。调查区浮游植物垂直分布总体特征是由水体表层到底层,细胞丰度逐渐减少。细胞丰度密集区位于水体表层,但是只有S2断面出现了次表层最大值现象,其垂直剖面分布同叶绿素a、铵盐、溶解氧以及盐度密切相关。整个调查区浮游植物的多样性程度是低的。     

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.