热带东北印度洋海域管水母类的群落结构特征

管水母是海洋浮游动物中的重要类群,通常可作为海流或水团的指示种,其分布受温度、盐度和食物的影响。本文根据2011年4月在东印度洋海域(5°S~5°N,80°~98.5°E)26个站的调查资料,分析了管水母种类组成、丰度分布和群落结构特征。共鉴定管水母37种,以热带大洋广布种和赤道种为主,其中扭形爪室水母Chelophyes contorta、巴斯水母Bassia bassensis、双小水母Nanomia bijuga和短深杯水母Abylopsis eschscholtzi是调查海域的优势种。依据调查站位设置及环境特征,将调查海域分东部断面、赤道断面和西部断面3个区域。各个调查站种数变化范围为2~14种,东部和西部断面的种类较丰富,而赤道断面近岸区种数低,离岸区种数增多。管水母的平均丰度为(1.04±0.58)个/m3,分布不均匀,东部断面和西部断面的丰度比赤道断面高,特别是赤道断面近岸区丰度在1.0个/m3以下。调查海区的管水母属于比较典型的热带大洋性生态类群。群落结构分析表明,东部和西部断面的群落结构相似度较高,二者与赤道断面的相似度均较低。调查海域管水母种类和丰度的分布受水文和生物环境因子的综合影响。双小水母Nanomia bijuga可作为东部断面和赤道断面近岸区沿岸水团的指示种,锥体浅室水母Lensia conoides和褶玫瑰水母Rosacea plicata可作为西部断面100m以下涌升水团的指示种。     

胶州湾毛颚类生态学研究

根据2006年9月—2007年8月胶州湾浅水Ⅰ型浮游生物网的调查资料,分析了胶州湾毛颚类的种类组成、数量分布、摄食、生物量、生产力情况。结果表明,本次调查共出现毛颚类3种:强壮箭虫(Sagitta crassa)、拿卡箭虫(Sagitta nagae)和百陶箭虫(Sagitta bedoti)。其中强壮箭虫全年出现,在数量上占有绝对优势,年平均密度达到45.3ind/m3;拿卡箭虫和百陶箭虫在秋、冬、春季出现,年平均密度分别为0.17ind/m3和0.35ind/m3。通过推算得到胶州湾毛颚类年平均生物量为107.92mg/m2,年平均生产力为1.47mgC/(m2·d),占浮游动物总生产力的11.6%。毛颚类对浮游动物生物量和生产力的摄食压力在冬季达到全年最大值,分别为5.71%和83.47%,在春季、夏季、秋季毛颚类对浮游动物生物量的摄食压力分别为0.67%、0.08%、6.48%,对生产力的摄食压力分别为27.00%、2.48%和48.88%。由此可见,在冬季毛颚类的摄食对浮游动物群落结构等可能会产生重要影响。     

南沙群岛海区上层毛颚类的种类组成和丰度分布

根据南沙群岛海区1997年11月(秋季)、1999年4月(春季)和7月(夏季)3个航次的调查资料,对上层水域毛颚类的种类组成和丰度分布进行了分析。共鉴定毛颚类18种。秋、春、夏3个季节毛颚类平均丰度分别为(6.86±3.08)、(9.95±3.50)和(7.11±3.34)个/m3。肥胖软箭虫(Flaccisag-ittaenflata)、龙翼箭虫(Pterosagitta draco)和太平洋齿箭虫(Serratosagitta pacifica)是3个航次调查共有的优势种,肥胖软箭虫占绝对优势。调查海区毛颚类按其生态特征可分为暖水广布种、大洋性暖水种和暖水近岸种三个类群,前两者对毛颚类丰度分布起决定性作用。毛颚类丰度分布受东亚季风驱动的南海环流影响显著,在秋季东北季风期,毛颚类分布趋势为西高东低,高值区位于西南部,与海洋锋对应;在夏季西南季风期,毛颚类主要分布在西北部,与该区域存在的海洋锋和上升流密切相关。作为最主要的食物来源,桡足类丰度是影响南沙群岛海区毛颚类丰度变化的重要因素。     

南沙群岛海区上层毛颚类的种类组成和丰度分布

根据南沙群岛海区1997年11月(秋季)、1999年4月(春季)和7月(夏季)3个航次的调查资料,对上层水域毛颚类的种类组成和丰度分布进行了分析。共鉴定毛颚类18种。秋、春、夏3个季节毛颚类平均丰度分别为(6.86±3.08)、(9.95±3.50)和(7.11±3.34)个/m³。肥胖软箭虫(Flaccisagitta enflata)、龙翼箭虫(Pterosagitta draco)和太平洋齿箭虫(Serratosagitta pacifica)是3个航次调查共有的优势种,肥胖软箭虫占绝对优势。调查海区毛颚类按其生态特征可分为暖水广布种、大洋性暖水种和暖水近岸种三个类群,前两者对毛颚类丰度分布起决定性作用。毛颚类丰度分布受东亚季风驱动的南海环流影响显著,在秋季东北季风期,毛颚类分布趋势为西高东低,高值区位于西南部,与海洋锋对应;在夏季西南季风期,毛颚类主要分布在西北部,与该区域存在的海洋锋和上升流密切相关。作为最主要的食物来源,桡足类丰度是影响南沙群岛海区毛颚类丰度变化的重要因素。     

东海陆架区毛颚动物的分布

毛颚动物是浮游动物中的重要类群,是典型的海洋浮游动物(仅Spadella属的种类生活于浅海岩石或海藻之间)。它的分布遍及世界海洋。在数量上也相当可观,根据1976年我们在东海两次采集的资料，夏、秋季它在浮游动物总生物量中的比例可达40%。 毛颚类是肉食性浮游动物中的饕餮者,不仅大量消耗桡足类,有时也能吞噬个体较小的燐虾、端足类和仔稚鱼等。它的数量高峰往往出现在其他草食性浮游动物的数量高峰之后。然而,它本身又是一些鱼类和肉食性浮游动物的食料。可见它在海洋食物网中所处地位的重要。在水域生产カ研究中,毛颚类的研究是了解某一海区生态转换效率的一项重要内容。 许多毛颚类是水团或海流的良好标志,例如,强壮箭虫(Sagitta crassa)可以作为黄海水团和日本内海低盐水的指标种,秀箭虫(Sagitta elegans)可以作为亲潮和里门寒流的指标种,锯齿箭虫(Sagitta serratodentata)在大西洋可以作为湾流的指标种,而多变箭虫(Sagitta decipiens)在印度西岸可以作为上升流的指标。又如人们所熟知的，Russell曾根据毛箭虫(Sagitta setosa)和秀箭虫的分布来推断北海低盐水团和天西洋高盐水团在英吉利海峡的相互推移和消长的情况。这类例子很多,兹不赘述。总之,毛颚类作为海流或水团的指标已日益受到各国海洋学工作者的重视。 本文根据东海陆架区综合考查1976年6-7月及8-9月,在127°E以西,北起32°N,南至26°30′N(6-7月在黄海南部增加一斜断面),用大型浮游生物网自底到表垂直拖网样品85份加以分析,对调查期间此海域内毛颚动物的分布作一概述。     

夏季青岛近海浮游动物种类组成、群落结构及多样性

2006年7月在青岛近海海域(35°19′～36°35′N, 119°50′～121°33′E)进行浮游动物采样调查,研究了青岛近海浮游动物的种类组成、群落结构及多样性.调查共鉴定浮游动物48种,浮游幼虫18类.种类数的平面分布为灵山湾、琅琊台湾附近海区较多,其他海区较少.优势种类有中华哲水蚤(Calanus sinicus)、强壮箭虫(Sagitta crassa)、拟长脚虫戎(Parathemisto gaudichaudi)、长尾类幼虫(Macrura larvae)和短尾类幼虫(Brachyura larvae).调查海区近岸暖温类群、近岸暖水类群、近岸低盐类群、温带外海类群四种生态类群共存,但以近岸暖温类群为主.浮游动物丰度、生物量的水平分布趋势与表层温度、盐度的水平分布趋势相似,都从调查海区的外海区向近岸逐渐降低;Shannon-weiner多样性指数与Pielou均匀度指数水平分布趋势与表层温度、盐度相反,从青岛近岸向调查海区外海逐渐降低.与该区域1959年同月份的调查数据相比,浮游动物主要种类组成、丰度、生物量差别不大,主要种类中华哲水蚤丰度有较大的增加.     

南黄海和东海毛颚类生态特征的研究Ⅰ.数量分布的特征

根据国家海洋局1977年12月份至1978年11月份在黄海南部和东海(28°~34°N,120°30'~127°00'E)广大海域进行周年逐月份的12航次综合调查资料,对该海域毛颚类数量变动、时空分布及其与环境因子的关系进行了分析.结果表明,本调查区毛颚类的数量以6~9月份较高,7月份为年最高值.1~4月份为年低值期,尤以4月份为最低谷.其中在数量上取主导作用的种类是肥胖箭虫(Sagitta enflata)、强壮箭虫(S.crassa)拿卡箭虫(S.nagae)和百陶箭虫(S.bedoti)等种类.在平面分布上,长江口以北毛颚类数量一般高于长江口以南的海域,在南黄海,除夏季外,其他季节均有出现高值.在东海高密集区一般出现在不同水系交汇区,尤其在长江冲淡水、沿岸水和外海高温高盐水交汇的锋面最为密集.这对于不同水系在研究区内运动和消长有一定的指示意义.     

台湾海峡西部毛颚类的生态研究

本文根据1984年5月-1985年2月在台湾海峡西部综合调查所获的浮游毛颚类样品,经分析共出现26种毛颚类,其中,尤以肥胖箭虫、百陶箭虫和拿卡箭虫最优势,本海区毛颚类虽周年可见,但以春、夏两季较多,尤其是夏季,其种类数和个体数皆居年的最高值,根据其分布特点,可分为近岸暖水性、近岸暖温性、广盐暖水和外海暖水等4个生态类群,其季节变化分布规律与沿岸水系、外海水系的消长和推移密切相关.     

渤海湾近岸海域浮游动物多样性

2004~2009年每年1~2次对渤海湾近岸海域选定站位进行采样,分析了其浮游动物的种类组成及种类多样性。结果表明,渤海湾近岸海域共鉴定出浮游动物9大类48种,主要种类为近岸低盐种,优势种主要为强壮箭虫(Sagitta crassa)、中华哲水蚤(Calanus sinicus)、大同拟长腹剑水蚤(Oithona similes)、小拟哲水蚤(Paracalanus parvus)和双刺纺锤水蚤(Acartia bifilosa)。通过不同年份渤海湾近岸海域浮游动物物种丰度、多样性指数、均匀度指数、优势度的对比,发现渤海湾海域生物环境质量在2007年前呈下降趋势,2007年后呈回升趋势。渤海湾近岸海域南部断面的浮游动物多样性指数呈减小趋势,北部断面的浮游动物多样性呈增大趋势。     

2007年夏季黄河口及其邻近水域浮游动物的群落特征

利用2007年夏季在黄河口及其邻近水域以浅水Ⅰ型浮游生物网采集的浮游动物样品,对浮游动物种类组成、丰度分布和群落结构进行分析;同时结合环境参数,初步探讨浮游动物与环境因子的关系.结果显示:夏季共鉴定浮游动物52种(不包括浮游幼体20类),浮游动物平均丰度为4769.6 ind/m3,香农-威纳指数和均匀度指数分别为2.34和0.48.浮游动物优势种类为:柱头幼虫(tornaria larvae)、小拟哲水蚤(Paracalanus parvus)、中华哲水蚤(Calanus sinicus)、强壮箭虫(Sagitta crassa)和双毛纺锤水蚤(Acartia bifilosa).其中体长较小(0.7～1.1mm)的柱头幼虫和小拟哲水蚤是最重要的优势种类.据各站位浮游动物种类组成和丰度,用聚类分析法可将该水域浮游动物划分为3个组群.相关性分析表明,影响黄河口及邻近水域浮游动物群落结构的主要环境因子组合为底温、表盐和水深.     

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.     

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.     

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.     

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.     

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.     

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.     

Flow Cytometric Analysis of Coastal Lagoon Bacterioplankton and Picophytoplankton: Fixation and Storage Effects

The effect of different fixation and storage protocols on the flow cytometric (FCM) simultaneous analysis of bacterioplankton and phytoplankton in coastal seawater samples (Mediterranean coastal lagoons) was investigated. FCM measurements (cell number, fluorescence and scatter characteristics) were obtained through DAPI staining. Three fixatives [glutaraldehyde (GA), formaldehyde (FA) and paraformaldehyde (PFA)] and two storage (3 months duration) methods (5 °C and −196 °C) were tested. Two dominant populations were detected in studied samples: bacteria and eukaryotic picophytoplankton. Adding fixatives (2% final concentration) appears necessary to obtain FCM exhaustive counts of all the bacteria and phytoplanktonic cells. This was related to the permeation effect of fixatives which allowed a better DAPI staining of the cells. Maximum fluorescence, i.e. optimal staining of the cells was obtained with FA or PFA, and significant lower fluorescences with GA. Fixed samples stored at 5 °C induced rapid cell loss. Only storage in liquid nitrogen of samples fixed with FA or PFA, allows mid-term (≥4 months) preservation of bacteria or picophytoplankton cell numbers, and limited evolution of DAPI-induced fluorescence and scatter characteristics.