2006年6月长江口低氧区及邻近水域浮游植物

根据2006年6月2-11日在长江12低氧区及邻近水域(26°-34°N,121°-126°E)27个站位的调查,对长江口低氧区及邻近水域的浮游植物群落结构特征进行了相关研究.经Utermohl方法初步分析,共发现浮游植物130种,隶属4门57属.甲藻和硅藻是2006年6月长江口低氧区及邻近水域的主要浮游植物门类,其优势物种是:具齿原甲藻Prorocentrum dentatum(=Prorocentrum donghaiense)、米氏凯伦藻Karenia mikimotoi、尖刺伪菱形藻Pseudo-nitzschia pungens、柔弱伪菱形藻Pseudo-nitzschia delicatissima、锥状施克里普藻Scrippsiella trochoidea和具槽帕拉藻Paralia sulcata.调查区浮游植物物种以广温、广布型为主.本次调查海域浮游植物的细胞丰度介于0.0026×105-37.37×105个/dm3.平均值为1.47×105个/dm3;甲藻占浮游植物细胞丰度的比例最大,细胞丰度介于0.0002×105-32.01×105个/dm3,平均值为1.39×105个/dm3;其次为硅藻,细胞丰度介于0.0001×105-18.72×105个/dm3,平均值为0.52×105个/dm3.具齿原甲藻和米氏凯伦藻所占丰度比例分别达到45.81%和26.44%,优势度分别为0.30和0.18.具齿原甲藻细胞丰度最高值出现在调查海域北部3号站-20m水层,为3.19×106个/dm3;米氏凯伦藻细胞丰度最高值出现在调查海域西南部29号站表层,为1.71×106个/dm3.浮游植物细胞丰度在水体中的垂直分布为表层最大,随着水深增加而逐渐降低.根据浮游植物的表层分布和断面分布可以发现,细胞丰度高值主要集中在调查区的西南部和北部.东南部浮游植物细胞丰度较低.同时调查海域东南部浮游植物多样性指数和均匀度指数较高,近岸低氧区和中部区域则较低.调查区水体层化现象明显,表层水和底层水之间氧的交换变弱,有机碎屑和浮游植物大量繁殖后沉降分解可能导致了底层低氧区的形成.     

福建漳江口红树林保护区浮游植物群落的季节变化研究

于2001年1月～2003年1月对福建省漳江口红树林区水体浮游植物群落的季节变化进行了研究。结果表明,漳江口红树林区浮游植物以硅藻门种类为主,优势种为长菱形藻(Nitzschia longissima)和菱形藻(Nitzschia sp.1)等,同时出现多种裸藻、绿藻和甲藻。本次调查共鉴定到浮游植物31属87种(包括变种),其中硅藻门23属75种(包括变种),蓝藻门3属3种,绿藻门1属4种,金藻门1属1种,甲藻门2属2种,裸藻门1属2种。浮游植物密度变化范围为2.78×104～1.14×106个/L,平均为3.51×105个/L,季节变化为双峰型。出现大量的底栖硅藻和淡水性藻类是该水域浮游植物的一个特点。浮游植物的组成和结构表明该水域水质较好。     

应用实时荧光定量PCR技术研究九龙江口水域米氏凯伦藻的分布

为快速精确监测九龙江口小型有毒赤潮藻的分布,本工作应用实时荧光定量PCR技术检测了2009年春(5月)、夏(8月)、秋(11月)3个季节九龙江口18个站位水样中米氏凯伦藻(Kareniamikimotoi)的密度.这3个季节分别对应九龙江口水域的丰水期、平水期、枯水期.结果表明,在九龙江口水中米氏凯伦藻的检出范围为未检出至2.3×104cells/dm3;其空间分布差异比较大,主要分布在厦门西港海域,其次是在高潮时的海门岛附近海域;海门岛以西水域几乎未监测到该藻的存在,仅5号站位有1个航次检出.米氏凯伦藻密度的季节分布差异也很明显,春、夏季的密度(最高检出值都达到了2.3×104cells/dm3)明显高于秋季的密度(最高检出值仅为5.4×103cells/dm3).本研究结果可为厦门西港以及九龙江口水域赤潮的研究与监测提供参考.同步进行的显微镜镜检技术没有观测到米氏凯伦藻的存在,可见在藻密度较低(低于103cells/dm3)的情况下,实时荧光定量PCR技术较传统镜检技术(检出限一般在103cells/dm3以上)可能更灵敏.该技术特异性好且操作简便,使对大样本的检测具有可行性,为实现沿岸海域赤潮的动态监测和深入研究奠定了基础.     

南麂列岛海洋自然保护区浮游植物生态研究

研究了南麂列岛海洋自然保护区浮游植物物种组成、数量分布、多样性指数及其与营养盐、浮游动物的关系.经鉴定,共发现浮游植物86种,隶属于33属.网样浮游植物平均密度为194.00×104个/m3,水样浮游植物平均密度为4.98×104个/m3,优势类群有角毛藻(Chaetoceros sp.)、角藻(Ceratuym sp.)、中肋骨条藻(Skeletonema costatum)、红色裸甲藻(Akashiwo sanyuineum)等.网样浮游植物多样性平均指数为2.28,水样浮游植物多样性平均指数为2.17.根据浮游植物组成特点,将其分为两个生态类群:近岸性和广布性类群,外海性类群.     

对虾养殖塘浮游植物的动态变化

2006年7月6日~2006年9月5日,对上虞地区南美白对虾养殖塘水体的浮游微藻群落结构进行调查分析。结果表明:养殖塘中共检出常见浮游微藻4门25属30种,其中蓝藻8种,绿藻18种,硅藻3种,裸藻1种。绿藻门藻种类最多,占藻类种类的60.0%,其次是蓝藻门藻占26.7%,硅藻门藻占10.0%,裸藻门藻占3.3%。主要蓝藻有项圈藻(Anabaenopsis sp)、色球藻(Chroococcus sp)、平裂藻(Merismopedia sp)、微囊藻(Microcystis sp)、小席藻(Phorimidium sp)、螺旋藻(Spirulina sp);常见绿藻有小球藻(Chlorella sp)、空星藻(Coelastrumsp)、卵囊藻(Oocys-tis sp)、盘星藻(Pediastrum sp)等;常见硅藻有舟形藻(Navicula sp)、尖针杆藻(Synedra acus)。养殖早期浮游微藻细胞数量为5.8×107/L,香浓多样性指数平均为1.2005。养殖后期浮游微藻细胞数量为2.5×107/L,香浓多样性指数平均为1.4939。浮游藻类多样性指数总体表现为养殖前期低后期高的特征。     

2009年夏季海南岛红树林区浮游植物群落结构特征（英文）

于2009年6月对海南岛红树林区浮游植物群落结构进行了研究。结果表明,海南岛红树林区水体浮游植物以硅藻门种类为主,主要优势种为骨条藻(Skeletonema sp.)、微小小环藻(Cyclotella caspia)、新月菱形藻(Nitzschia closterium)、颤藻(Oscillatoria sp.),同时出现多种裸藻、绿藻和甲藻。本次调查共鉴定到浮游植物46属97种(包括变种),其中硅藻门25属59种,绿藻门9属18种,蓝藻门7属10种,裸藻门2属4种,甲藻门5属5种,金藻门1属1种。浮游植物密度变化范围为(0.29～1.96×10~6) cells/L,平均为8.85×10~5cells/L。浮游植物的组成和结构表明红树林区水质较好,但新英港、三亚河、彩桥等红树林区,水体质量有下降的可能,应引起关注。     

2004年秋季长江口及其邻近水域浮游植物群集

根据2004年11月在长江口及其邻近水域37个测站采集的浮游植物水样Utermhl方法分析结果,研究了该水域浮游植物群集特征,包括浮游植物优势种、细胞丰度和多样性指数,并进行了其与环境因子的典范对应分析(CCA).调查区浮游植物组成以硅藻和甲藻为主,其丰度所占比例分别为67.97%和28.94%.浮游植物优势种为中肋骨条藻、具槽帕拉藻和菱形海线藻等温带近岸种.浮游植物细胞丰度为0.27×103~133.38×103 个/L,平均为4.97×103 个/L,高值出现在调查区的南部和东南部.Margalef物种丰富度指数和Shannon-Wiener多样性指数在各测站变化较大.分析表明,优势种中肋骨条藻的分布与硝酸盐和硅酸盐呈正相关,具槽帕拉藻和菱形海线藻与温度呈正相关.     

高公岛近岸海域浮游植物群落特征

2009年8月对高公岛附近海域的海洋浮游植物及环境因子进行了调查,在14个调查站位共鉴定浮游植物4门36属81种,其中,硅藻门25属63种,占种数的77.78%;甲藻门9属16种,占种数的19.75%,蓝藻门1属1种,占种数的1.23%,金藻门1属1种,占种数的1.23%。浮游植物生态类型主要以低盐近岸性类群为主,辅以少量的广温广盐性类群。主要优势种为斯氏几内亚藻、短角弯角藻、拟旋链角刺藻、扭链角刺藻。优势度分别为0.688、0.207、0.142、0.103。浮游植物的细胞丰度范围为0.458×105～3.134×105个/L,平均值为1.180×105个/L。群落特征指数变幅较大(种类数为19～43,丰富度指数为1.064～2.364,多样性指数为2.069～3.428,均匀度指数为0.485～0.677)。丰富度指数均值为1.753多样性指数均值为2.926,均匀度指数均值为0.592。相关性分析表明,仅均匀度指数与水温之间具有显著的相关性,相关系数(r)为0.544,P<0.05,水温越高,均匀度指数越高;其它因子之间均没有显著的相关性。高公岛近岸海域水质状况的生物多样性指数评价显示,该海域水质总体处于轻污染,尚适宜浮游植物的生长。     

胶南近海及邻近海域夏、冬季浮游植物群落结构

分析了2006年夏季(8月)和冬季(12月)在青岛胶南至日照近海进行调查所采集的水样,对调查海域的浮游植物群落的物种组成,细胞丰度的平面分布和垂直分布,优势种分布和群落的多样性指数等进行分析研究.初步鉴定浮游植物3门54属111种,硅藻占绝对优势.夏季主要优势种为旋链角毛藻(Chaetoceros curvisetus)、窄隙角毛藻(Chaetoceros affinis)、梭角角藻(Ceratium fusus)、虹彩圆筛藻(Coscinodiscus oculus-iridis),中肋骨条藻(Skeletonema costatum)在个别站位有较大丰度,导致该站位多样性降低.冬季主要优势种为派格棍形藻(Bacillaria paxillifera)、虹彩圆筛藻、叉状角藻(Ceratium furca)和小环藻(Cyclotella spp.).夏季浮游植物细胞丰度介于48.96～195.88×105个/m3,平均61.12×105个/m3;冬季介于10.00～48.33×105个/m3,平均19.27×105个/m3.夏季细胞丰度与胶州湾水域相近,冬季细胞丰度高于南黄海的历史数据.冬季的香农-维纳指数和Pielou均匀度指数都优于夏季,而夏季的细胞丰度和物种丰富度优于冬季.     

台山核电邻近海域春秋季浮游植物群落结构特征

根据2013年4月(春季)和9月(秋季)2个航次调查数据,对台山核电邻近海域浮游植物种类组成、时空分布及多样性指数等群落特征进行了分析。共鉴定浮游植物3门61种,其中硅藻类48种,占78.69%;甲藻类11种,占18.03%;金藻类2种,占3.28%。种类组成以暖水种和广温种为主。浮游植物丰度均值春季(11.78×107个/m3)与秋季(29.37×107个/m3)无明显差异;然而丰度水平变化较大,整体表现为春秋两季核电站温排水口附近站位均低于远离站位。春秋两季浮游植物优势种共出现了7种,春季仅出现了中肋骨条藻Skeletonema costatum1种,优势度高达0.996;秋季出现了7种,包括中肋骨条藻(0.291)、柔弱拟菱形藻Pseudo-nitzschia delicatissima(0.222)、拟弯角毛藻Chaetoceros pseudocurvisetus(0.214)和并基角毛藻Chaetoceros decipiens(0.056)等。海域春季Shannon-Wiener多样性指数H′、Pielou均匀度指数J′和Margalef物种丰富度指数D均值分别为0.55、0.18和0.50;秋季分别为2.80、0.62和0.80。多样性指数显示台山核电附近海域水质状态受到了一定程度的污染。     

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.     

A Review of Some Environmental Issues Affecting Marine Mining

This article reviews information recently available from existing marine and coastal mining for responses to environmental issues affecting marine mining at different depths. It is particularly but not exclusively concerned with those issues affecting seabed biodiversity impact and recovery. Much information has been gathered in the past 10 years from shallow mining operations for construction aggregate, diamonds, and gold, from coastal mines discharging tailings to shallow and deep water, and from experimental deep mining tests. The responses to issues identified are summarized in a series of eight tables intended to facilitate site-specific consideration. Since impacts can spread widely in the surface mixing layer SML, and can affect the biologically productive euphotic zone, the main issues considered arise from the depth of mining relative to the SML of the sea. Where mining is below the SML, the issue is whether it is environmentally better to bring the extraction products to the surface vessel for processing (and waste discharge), or to process the extraction products as much as possible on the seabed. Responses to the issues need to be sitespecific, and dependent on adequate preoperational environmental impact and recovery prediction. For deep tailings disposal from a surface vessel, there are four important environmental unknowns: (1) the possible growth of "marine snow" (bacterial flocs) utilizing the enormous quantities of fine tailings particles (hundreds or thousands of metric tons per day) as nuclei for growth, (2) the possibility that local keystone plankton and nekton species may migrate diurnally down to and beyond the depth of deep discharge and hence be subjected to tailings impact at depth, (3) the burrow-up capability of deep benthos and their ability to survive high rates of tailings deposition, and (4) the pattern and rate of dispersion of a tailings density current through the deep water column from discharge point to seabed. Actions to obtain relevant information in general and site-specifically are suggested.     

Increased Particle Fluxes at the INDEX Site Attributable to Simulated Benthic Disturbance

Particle fluxes were measured 7 m above the sea bottom during the predisturbance, disturbance, and postdisturbance periods by using time series sediment traps attached to seven deep-sea moorings deployed in the INDEX experiment site in the Central Indian Basin. The predisturbance particle fluxes varied between 22.3 to 55.1 mg m -2 day -1 . Increased and variable particle fluxes were recorded by the sediment traps during the disturbance period. The increase observed was 0.5 to 4 times more than the background predisturbance fluxes. The increases in particle fluxes (~4 times) recorded by the sediment trap located in the southwestern direction (DMS-1) were the greatest, which could be the result of preferential movement of resuspended particles generated during the deep-sea benthic disturbance along the general current direction prevailing in this area during the experimental period. Also, the traps located closer to the disturbance area recorded greater fluxes than did the traps far away, across the Deep Sea Sediment Resuspension System path. This variability in recorded particle fluxes by the traps around the disturbance area clearly indicates that physical characteristics such as grain size and density of the resuspended particles produced during the disturbance had an important effect on particle movement. The postdisturbance measurements during ~5 days showed a reduction in particle fluxes of ~50%, indicating rapid particle settlement.     

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.     

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。     

Determination of In Situ Sediment Shear Strength from Advanced Piston Corer Pullout Forces

The advanced piston corer (APC) has been used by the Ocean Drilling Program since 1985 for recovering soft sediments from the ocean floor. The pullout force measured on extracting the core barrel from the sediment is shown to correlate with the average shear strength of the sediment core measured in the ship's laboratory. A simple rule of thumb is derived relating the shear strength of the sediment to the pullout force. Multiple APC holes at individual sites allow the consistency of the pullout measurements to be assessed. The effects of different operational procedures during APC coring are also explored. Although generally applicable, the correlation between pullout force and laboratory measurements of shear strength breaks down for some APC holes, possibly because of the disturbance of some sediment types during the APC coring process. A better understanding of the physical process of APC coring, and its effect on the properties of the sediment both inside and immediately outside the core barrel, would indicate what confidence can be put on the measurement of pullout force as a way of evaluating the in situ shear strength of deep sea sediments.     

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.     

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.