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1.
南沙群岛海区秋季浮游植物物种多样性及数量变化 总被引：3，自引：0，他引：3
根据1997年11月南沙群岛海区的调查资料,对调查海区的浮游植物种类组成、优势种、物种多样性及数量分布特点进行了初步分析。鉴定网采浮游植物共121种,隶属2个门类33属。垂直分层0—75m和75—150m浮游植物细胞数量平均值分别是0.070×104cells·m-3和0.044×104cells·m-3。0—75m层浮游植物细胞数量的高值区出现在调查海区的东部和东南部,最高值出现在安渡滩附近的21号站;75—150m浮游植物细胞数量高值区出现在32号站附近。垂直分布的明显特点是随深度增加浮游植物种类和数量呈减少趋势。三叉角藻Ceratiumtrichoceros和夜光梨甲藻Pyrocystisnoctiluca是0—75m层和75—150m层共有的优势种。0—75m层和75—150m层浮游植物Shannon-Wiener多样性指数平均值分别为3.40和2.07,均匀度平均值分别为0.79和0.60。研究结果表明,秋季浮游植物细胞数量比春、夏季低,浮游植物由硅藻、甲藻组成,甲藻在数量和种类上都占优势。初步探讨了南沙群岛海区秋季浮游植物种类和数量分布与营养盐、温度与盐度、海流及浮游动物等环境因子的关系。 相似文献
2.
北麂列岛岩相潮间带底栖生物群落的组成特征 总被引：15，自引：0，他引：15
本文报导了1997.7-1998.4期间北麂列岛岩相潮间带底栖生物群落的组成特征.研究结果表明:总平均生物量和栖息密度分别为5091.80g·m-2和4269个·m-2; 生物量和栖息密度的水平分布为关帝山＞大筲箕屿＞海利＞壳菜岙,垂直分布为中潮区＞低潮区＞高潮区,生物量和栖息密度的季节变化分别为冬季＞春季＞秋季＞夏季和冬季＞秋季＞春季＞夏季.数量的水平分布主要受海岸开敞度及浪击度的影响、垂直分布主要受潮区及浪击度的影响、季节变化主要受温度和动植物繁殖的影响. 相似文献
3.
福建东山岛海域游泳生物生态和资源评析 总被引：1，自引：0，他引：1
1990年4个季度月调查,东山岛海域有游泳生物181种.种类的季节分布呈秋季>夏季>春季>冬季.湾内比湾外多49种;生物量的优势种为斑,密度的优势种为长颌棱;生物量的季节分布呈冬季>秋季>夏季>春季,密度呈夏季>秋季>冬季>春季;湾内平均月生物量和密度比湾外高4.44倍和3.51倍;种类数和生物量与水深和盐度呈显着负相关,种类数与水温呈显着正相关;与1985年同期比较,生物量和密度分别减少28.69%和23.00%,其中11种重要经济鱼类下降幅度达84.35%和83.45%;能流估算该海域游泳生物年自然生产量为25731t,可捕量11579t,实际年均渔获量达1.71×104t;应用Schaefer剩余产量模式估算定置网最适张网数为7618张. 相似文献
4.
渤海水域叶绿素a的分布及初级生产力的估算 总被引：23，自引：4，他引：23
1980-1981年在渤海90个测站上进行了浮游植物种类组成及数量变化、叶绿素含量、海面辐照度、海水光学参量以及海洋水文要素调查,还作了浮游植物光合作用率和同化系数的测定。绘出渤海水域各季节叶绿素a和初级生产力的平面分布图。渤海水域表层叶绿素a的平均值春季、夏季、秋季和冬季分别为1.04,0.69,1.27和0.64毫克/米3。初级生产力的测定采用叶绿素法。通过调查计算得出渤海初级生产力平均值:春季为357毫克碳/米2·日;夏季为171毫克碳/米2·日;秋季为305毫克碳/米2·日;冬季为88毫克碳/米2·日。渤海初级生产力的年平均量为90克碳/米2·年。整个水域全年有机碳生产量约为800万吨。 相似文献
5.
据1990年11月至1991年8月间调查资料，提出刘公岛水域内叶绿素－a含量的时空分布和初级生产力的分布与变化。指出此分布与该水域温度和营养盐含量密切相关。叶绿素－a含量以春季最高，冬季次之，秋季稍低，夏季最低。年变幅为0．21～2．45mg／m3，年平均值为1．02mg／m3。初级生产力以夏季最高，春季次之，秋季略低，冬季最低，年变幅为33．40～512．72mg·c／m2·d，年平均值为181．15mg·c／m2·d。 相似文献
6.
浙江舟山群岛邻近海域微,小型浮游植物与赤潮生物研究 总被引：7，自引：0，他引：7
报道了舟山群岛邻近海域未发生赤潮与发生赤潮时的微、小型浮游植物组成、数量分布、赤潮生物种类与环境的关系。舟山群岛邻近海域共有浮游植物 1 69种 ,其中赤潮生物为 59种。赤潮发生时比未发生赤潮时水域的浮游植物密度高 1 0～ 1 0 0个 /dm3,浮游植物密度与硅酸盐、硝酸盐浓度成负相关 ,与溶解氧和透明度成正相关。平均浮游植物密度 :春季表层水样为4.5× 1 0 4 个 /dm3,底层水样为 5.2× 1 0 3个 /dm3,网样为 2 .7× 1 0 5个 /m3;秋季网样为 3.7× 1 0 6个 /m3。表层水样的赤潮生物优势种 :春季为微型的三鳍原甲藻 ,平均细胞密度为 3.3× 1 0 5个/dm3,占总细胞密度的 77.2 % ;秋季为微型的中肋骨条藻 ,平均密度为 2 .7× 1 0 3个 /dm3,占总细胞密度的 72 .2 %。三鳍原甲藻、海洋原甲藻、夜光藻等为浙江舟山群岛邻近海域常见的有害赤潮生物。 相似文献
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2000年10-11月和2001年3-4月对东、黄海海区进行了调查,采用表面荧光显微镜计数的方法对蓝细菌(聚球菌属, Synechococcus spp.)的丰度、生物量、生态分布特点以及其在浮游植物总生物量中所占百分比进行了研究.结果表明,秋季蓝细菌的丰度为1.72×104 cell/ml,春季为4.83×104 cell/ml,春季是秋季的2.81倍;秋季蓝细菌的生物量为5.07μgC/L,春季为 7.25μgC/L,春季是秋季的1.43倍;秋季蓝细菌占浮游植物总生物量的百分比为 43.9%,春季为42.4%,两个季节大致相当,但该百分比的水平分布秋季与春季存在明显差别. 相似文献
8.
胶州湾聚球菌(Synechococcus spp.)蓝细菌的分布及其对初级生产力的贡献 总被引：1，自引：0，他引：1
自2002—2004年应用表面荧光显微镜计数法对胶州湾聚球菌(Synechococcusspp.)蓝细菌的季节变化、月变化及其对浮游植物总初级生产力的贡献进行调查研究。结果显示,胶州湾Synechococcusspp.丰度处于0.16×104—21×104cells/ml之间,最大与最小值之间相差约两个数量级,其中夏天Synechococcusspp.丰度最高,春、秋季相当,冬季最低。夏季Synechococcusspp.丰度平均值约是冬季的3—4倍。Synechococcusspp.的季节变化呈现一定周期性。Synechococcusspp.月最高值(21×104cells/ml)出现在8月的B2站表层,最低值(0.15×104cells/ml)出现在12月A1站表层。对18个月的胶州湾Synechococcusspp.水平分布进行分析,结果显示,河口和近岸区域Synechococcusspp.丰度相对较高。以D8站为典型站位对Synechococcusspp.垂直分布进行的分析发现,不同季节Synechococcusspp.最大值出现的水深不同。胶州湾Synechococcusspp.在总浮游植物生物量中所占的比例在0.2%—77%之间,平均为4.7%。此外,对2003—2004年温度与Syne-chococcusspp.丰度的相关性分析中发现,两者呈正线性相关(相关系数达0.6)。 相似文献
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为掌握江苏全海域刀鲚资源状况,为后期长江禁捕效果评估提供支撑资料, 2017年5月、8月、11月与2018年2月在江苏海域(31°45′~35°00′N, 119°30′~125°00′E)分别进行了4次渔业资源调查, 并绘制了尾数资源密度与重量资源密度分布图, 利用SPSS 26软件对当年的刀鲚资源状况进行评估, 积累长江禁渔前刀鲚鱼种系统数据。结果表明: (1) 刀鲚除秋季(11月)与冬季(2月)存在部分群体分布于“机轮拖网渔业禁渔区线”(以下简称“禁渔区线”)外侧之外, 其余时间均在江苏近岸海域(江苏境内“禁渔区线”到海岸线之间的水域)栖息洄游, 江苏近岸海域是刀鲚主要栖息索饵水域; (2) 春季(5月)影响江苏海域刀鲚分布的环境因子较多, 主要有水温、盐度、溶氧、深度、透明度等, 这可能与刀鲚正处于产卵旺期, 对环境因子变化敏感有关; 夏季(8月)影响江苏海域刀鲚分布的环境因子是透明度, 此时刀鲚刚结束产卵不久, 返回近海后急需补充能量, 丰富的营养物质成为影响其分布的主要因素, 此时为北半球夏季, 江苏省境内60余条入海河流正值汛期, 入海河水携带大量的营养物质, 成为返海刀鲚优良的索饵场; 秋季水温降低, 刀鲚开始越冬洄游, 水温成为影响刀鲚分布的重要因素; 冬季, 随着刀鲚性腺再次发育成熟, 新一轮的生殖洄游开始, 刀鲚栖息水层上升, 水深成为影响冬季刀鲚分布的关键因素; (3) 与长江禁捕后其他研究者在长江口收集到的刀鲚规格、全长-体重拟合方程综合对比, 发现自“长江十年禁捕”逐步实施后, 刀鲚种群渔获规格逐渐增大, 全长、体重开始逐渐增长, 长江刀鲚种群呈现资源恢复趋势。 相似文献
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根据2006年12月30日—至2007年1月17日北黄海的调查资料,对该海域浮游植物的种类组成、优势种、丰度及其分布和多样性等基本状况进行了分析。本次调查共鉴定浮游植物4门68属131种,主要以温带近岸和广布性种为主,其中硅藻有53属113种,占总种数的86.3%,甲藻有11属16种,占总种数的12.2%。浮游植物丰度平均值为88.89×104个/m3,硅藻丰度平均值为86.58×104个/m3,甲藻丰度平均值为2.28×104个/m3,硅藻丰度分布趋势决定了浮游植物丰度的分布趋势。辽宁南岸是浮游植物密集区,山东半岛北岸其次,而北黄海中部是浮游植物的稀疏区。优势种为:短角弯角藻(Eucampia zodiacus)、具槽帕拉藻(Paralia sulcata)、尖刺拟菱形藻(Pseu-do-nitzschia pungens)、密连角毛藻(Chaetoceros densus)、柔弱角毛藻(Chaetoceros debilis)、刚毛根管藻(Rhizosolenia setigera)。浮游植物群落Shannon-Weiner物种多样性指数平均值为1.80,Peilou均匀度指数平均值为0.42。与1959年1月相比,2007年1月北黄海浮游植物丰度由150.00×104个/m3降为88.89×104个/m3,下降了近41%,硅藻丰度由148.00×104个/m3降为86.58×104个/m3,而甲藻丰度由1.25×104个/m3上升为2.28×104个/m3,占浮游植物丰度的比例由0.8%上升为2.5%。主要优势种及优势属也发生了一定程度的变化,但浮游植物群落结构仍以硅藻为主、甲藻其次,浮游植物丰度总的分布格局变化不明显。 相似文献
11.
Chandralata Raghukumar G. Sheelu P. A. Loka Bharathi Shanta Nair C. Mohandass 《Marine Georesources & Geotechnology》2001,19(1):1-16
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. 相似文献
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Arne Schnack-Friedrichsen Angela M. Davis Jim D. Bennell Dei G. Huws 《Marine Georesources & Geotechnology》2001,19(4):221-243
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. 相似文献
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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. 相似文献
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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。 相似文献
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Shigehisa Nakamura 《Marine Geodesy》2000,23(1):55-61
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. 相似文献
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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. 相似文献
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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. 相似文献
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Phylogenetic diversity and phenotypic characterization of cultivable bacterioplankton isolated from polar oceans 总被引：1，自引：0，他引：1
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. 相似文献