2011～2012年度大亚湾海域浮游植物群落的季节变化

于2011年12月至2012年11月采集了大亚湾海域9个站位表层水样, 对大亚湾海域的浮游植物群落结构进行了周年调查。本次调查共鉴定出浮游植物93种, 其中硅藻门40属55种, 甲藻14属33种。秋季浮游植物种类较为丰富, 春季和夏季较低。浮游植物细胞密度为41～396个/mL, 年平均值为72.5个/mL。浮游植物细胞密度夏季较高, 春季较低。硅藻是浮游植物优势类群, 年均占浮游植物总细胞密度的83.6%, 优势硅藻主要有拟菱形藻(Pseudo-nitzschia spp.)、丹麦细柱藻(Leptocylindrus danicus)、中肋骨条藻(Skeletonema costatum)等。甲藻细胞密度一般较低, 各季节甲藻的百分比含量为1.5%～32.6%, 春季血红哈卡藻(Akashiwo sanguinea)大量出现, 最大细胞密度高达82.3 个/mL。浮游植物种类多样性指数(H′)和均匀度(J)在冬季和秋季较高, 夏季较低; 远岸站点较高, 近岸站点较低。研究结果说明虽然大亚湾浮游植物群落结构仍以硅藻占据优势, 但甲藻种类与数量及百分比具有明显上升的趋势, 同时近岸海域的富营养化导致了浮游植物种类多样性的下降。     

渤海中部和渤海海峡及邻近海域浮游植物群落结构的初步研究

对渤海调查区浮游植物的群落及其动力学进行了初步研究。结果表明 ,浮游植物群落主要由硅、甲藻组成 ,也有少数的蓝藻、绿藻和硅鞭藻出现 ,其生态类型主要为温带近岸型。粒级大小以微型浮游植物为主 ,依次为小型浮游植物 (包括网采浮游植物 )、微微型浮游植物。浮游植物群落的平面分布与各环境因子密切相关 ,其中水体中化学和生物相互作用所形成的浮游植物团块是其平面分布的主要特征。调查海域存在三个典型的浮游植物区划 :渤海海峡区、渤海湾区和黄河河口区。追踪实验的结果表明 ,调查区浮游植物群落短周期 (几天 )的变化是由关键种所驱动而非优势种。渤海海峡浮游植物群落的周年变化为双周期型 ,春季水华主峰出现在 4月 ,而秋季次高峰出现在 9月。春季浮游植物以小型细胞硅藻占优群落为主 ,秋季以大型细胞硅藻 甲藻联合占优群落为主。群落季节和周年的变化以种类演替 (speciessuccession)为主而非种类接替 (speciessequence)。与历史调查资料相比 ,1 998— 1 999年的观测表明浮游植物群落由硅藻占绝对优势逐渐转变为硅藻 甲藻共存为主的群落。甲藻的占优以及绿藻在特定时期的普遍出现反映了渤海海区营养盐结构比例变化对海区生态系统结构的影响 ,氮 /磷比率的增加和硅 /氮比率的降低是造成这一结果的     

2001—2002年粤东柘林湾浮游植物的生态学研究

2001年7月-2002年7月对粤东赤潮重灾区柘林湾进行的浮游植物周年调查表明,柘林湾共有浮游植物68属183种.其中硅藻为最优势类群,共51属143种,占总种数的 77.8%;甲藻11属34种;其它浮游植物类群6属6种.调查海区浮游植物群落的种类丰富度、细胞密度、生物多样性和均匀度的平面分布均表现为湾外高于湾内和湾内外侧高于湾内内侧的基本格局,但黄冈河河内浮游植物群落的构成却呈现种类少而密度高的特点.调查期间浮游植物的总细胞数年均值为16.9×104cells/L,周年变动模式为双峰型(高峰位于8月和4月).与上一个周年调查(2000年5月-2001年5月)的总细胞数年均值(36.0×104cells/L)和单峰型周年变动模式(最高峰位于7月)相比,差异较大.这可能是2001-2002年厄尔尼诺现象导致粤东地区气候异常、干旱少雨,以及调查海区无机磷剧减45%所致.中肋骨条藻(Skeletonema costatum)为该湾的全年优势种,在群落总细胞数中的百分比年均值从上一年度的58.7%上升至本年度的71.0%,导致Shannon-Wiener多样性指数从上一年度的1.91减少至本年度的1.75.中肋骨条藻的绝对占优已在很大程度上改变了该湾浮游植物的群落结构,并使中肋骨条藻赤潮的发生机率大大增加.陆源排污、大规模增养殖业和水体交换对柘林湾高营养盐低浮游植物密度及浮游植物群落的时空分布具最重要的影响.     

钦州湾海域网采浮游植物群落结构季节变化

基于2013-2014年钦州湾海域4个季度月的现场调查数据,研究了网采浮游植物的群落结构。共鉴定出浮游植物6门54属134种(包括变型和变种),其中硅藻种数共107种,占79.9%;甲藻23种,占17.2%。调查期间的优势种,除球形棕囊藻外其余均为硅藻,并多为广温性种。不同季节的浮游植物细胞丰度差异明显,表现为2014-08最高,2013-11最低。相关性分析表明浮游植物丰度与环境因子的相关性存在季节变化,春季受硝酸盐影响显著,夏季与温度、盐度均呈负相关,秋季受盐度和DIN影响显著,冬季则与环境因子相关性不显著。浮游植物群落多样性指数及均匀度指数较高,物种较丰富,群落结构稳定性较高。     

2000年秋季渤海的网采浮游植物群落

研究了2000年秋季覆盖渤海60个测站的网采浮游植物物种及其群落特征,共发现浮游植物3门35属64种(不包括未定名物种).物种主要以硅藻为主,但甲藻在群落中的比重也很明显,在个别站位上会成为优势类群.优势种主要为偏心圆筛藻、三角角藻、浮动弯角藻等,其中的偏心圆筛藻、浮动弯角藻、布氏双尾藻、梭状角藻和叉状角藻是秋季渤海浮游植物的关键种.细胞丰度的平面分布由浮游硅藻的分布决定,其高值区分布在渤海中北部、渤海湾南部和渤海海峡南部.浮游甲藻在渤海湾北部存在高值区.由于渤海环流的影响在渤海中北部存在浮游植物群落的交错区,此区物种丰富度高、多样性水平高和细胞丰度高.秋季渤海浮游植物群落物种丰富度、Shannon-Wiener多样性指数和均匀度的高值区在渤海中部,但整个秋季浮游植物群落的多样性程度是较低的.     

大鹏澳牡蛎养殖对浮游植物种群结构的影响研究

于2013年8、10月及2014年2、5月对大鹏澳牡蛎养殖区及其邻近海域进行了采样调查。利用设置的3个站位(牡蛎养殖区S1、养殖区外S2、靠近湾口S3)的数据研究了牡蛎养殖对海区浮游植物种群结构和丰度的影响。本次考察共鉴定出大鹏澳浮游植物58属144种,丰度为6.15×103—5.94×106cells/L。其中,硅藻36属100种,占种类总数的69.4%,丰度在4.5×103—5.93×106cells/L之间;甲藻15属34种,占总种类的23.6%,丰度范围为1.5×102—4.53×104 cells/L;蓝藻、绿藻、隐藻等共7属10种。在牡蛎养殖期(8月至2月),养殖区内养殖水层浮游植物总丰度低于非养殖区,硅藻丰度占浮游植物总丰度的90%以上,硅藻丰度与总浮游植物细胞丰度的空间分布特征一致;与硅藻空间分布特点不同,养殖区内甲藻丰度显著低于非养殖区。牡蛎收获后的5月,养殖区内的甲藻丰度高于非养殖区。牡蛎养殖区站位S1浮游植物多样性指数平均值为1.35,明显低于非养殖区S2(2.68)和S3(2.69)。与此相似,养殖区内站位S1均匀度J(0.27)明显低于非养殖区站位S2(0.49)和S3(0.51)。本研究表明,大鹏澳牡蛎养殖对浮游植物群落结构造成了一定影响,能够显著降低浮游植物丰度、种类多样性和均匀度。     

夏季外海水入侵对大亚湾浮游植物群落结构的影响

夏季大亚湾存在由粤东沿岸上升流所引起的外海水入侵现象,且入侵强度存在年际差异,作者利用大亚湾2004～2017年历年夏季航次调查数据,将弱入侵年份与强入侵年份进行对比分析,以探讨外海水入侵对大亚湾浮游植物群落结构的影响。结果显示,当外海水入侵由弱变强时,湾内水体理化特征发现显著变化,水体由高温低盐转变为低温高盐,N、P等营养盐含量出现下降。海水理化性质的改变导致了浮游植物群落结构的变化,硅藻、甲藻种类数以及浮游植物Shannon-wiener指数均出现升高;浮游植物总丰度和硅藻丰度下降,甲藻丰度变化不明显;常见浮游植物种类伪菱形藻属(Pseudo-nitzschiasp.)、角毛藻属(Chaetocerossp.)和叉角藻(Ceratiumfurca)丰度出现下降,而中肋骨条藻(Skeletonemacostatum)和菱形海线藻(Thalassionemanitzschioides)丰度出现升高;优势种由单一硅藻种类向硅藻和甲藻共为优势转变。此外,外海水入侵还会通过改变海水理化因子的空间分布以及湾内上层水体流向来影响浮游植物群落结构的空间分布。     

昌黎黄金海岸国家级自然保护区海域浮游植物群落结构

2016年对昌黎黄金海岸国家级自然保护区海域浮游植物群落结构进行了春季(5月)和夏季(8月)2个航次调查,描述了浮游植物的种类组成、细胞数量、生物多样性指数、均匀度指数等群落特征,分析了浮游植物群落的变化及平面分布趋势。结果表明,2个航次共检出浮游植物70种,以硅藻为主,细胞数量平面分布差异较大,春季生物多样性指数及均匀度较低,夏季多样性指数和均匀度总体水平较高。     

渤海浮游植物群落结构及与环境因子的相关性分析

2011年11月25日-12月1日在渤海(37°00′-40°00′N,118°00′-121°00′E)21个站位进行了水文、化学和生物的综合调查,应用Uterm觟hl方法对调查海域的浮游植物群落进行了研究,并将群落数据与环境因子(温度、盐度和营养盐)进行了相关性分析。本次调查共发现浮游植物3门30属65种,主要由硅藻和甲藻组成,还有少量的金藻,生态类型以温带近岸性物种为主,主要优势种为:具槽帕拉藻[Paralia sulcata(Ehrenberg)Cleve]、偏心圆筛藻(Coscinodiscus excentricus Ehrenberg)、梭状角藻[Ceratium fusus(Ehrenberg)Dujardin]、相似曲舟藻(Pleurosigma affine Grunow)、星脐圆筛藻(Coscinodiscus asteromphalus Ehrenberg)和菱形藻(Nitzschia sp.)等。调查区浮游植物细胞丰度介于0.89×103~16.4×103cells/L,平均值为4.36×103cells/L。表层浮游植物细胞丰度分布主要受硅藻刻画,高值区集中在辽东湾南侧和渤海海峡西侧海域,甲藻则主要集中在调查区西部和西北部海域。细胞丰度在水体中的垂直分布为随水深增加先升高后降低。调查区浮游植物群落多样性指数和均匀度指数均在调查区中部海域较高,在外侧海域较低。与历史资料的对比发现,近30年来渤海中部海域浮游植物群落结构由早期的硅藻占绝对优势转化为硅藻和甲藻联合占优。PCA和CCA分析以及与历史资料的对比表明,渤海中部海域营养盐结构的改变可能是造成这种转化的主要原因。     

热带西太平洋Y3和M2海山区网采浮游植物群落结构特征

研究了热带西太平洋雅浦Y3海山冬季和马里亚纳M2海山春季网采浮游植物群落结构,对调查区浮游植物的物种组成、优势种类、细胞丰度以及多样性指数进行了分析。结果表明,两个海山区共鉴定浮游植物4门50属219种,其中硅藻门30属106种,甲藻门17属112种,蓝藻门1属2种,金藻门2属3种。两个航次研究区浮游植物优势种均以链状硅藻如根管藻(Rhizosolenia)、半管藻(Hemiaulus)和角毛藻(Chaetoceros)等属的种类为主,此外太阳漂流藻(Planktoniella sol)、铁氏束毛藻(Trichodesmium thiebautii)以及部分角藻(Ceratium)物种优势度也比较明显。Y3海山区浮游植物细胞丰度介于1.60～16.61 cells/L,平均值为5.02 cells/L; M2海山区浮游植物细胞丰度介于1.36～10.20 cells/L,平均值为4.12cells/L。两个海山区浮游植物细胞丰度的分布趋势均受硅藻影响较大,甲藻细胞丰度相对较低。在属的水平上,角毛藻、根管藻、角藻和半管藻等属的细胞丰度对两个海山区浮游植物总细胞丰度的贡献较大。多样性指数方面, Y3海山区浮游植物群落香农-威纳指数H′(shannon-wiener index)介于3.95～4.69,平均值为4.30; M2海山区浮游植物群落香农-威纳指数介于3.23～4.46,平均值为3.83。两个海山区浮游植物群落多样性指数均处于较高水平,但站位间的变化不明显。目前,关于热带西太平洋海山区浮游植物群落结构的研究还非常缺乏,亟需后续研究的补充。     

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.