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1.
南海西北部浮游生物中多孔放射虫的组成与分布 总被引：1，自引：0，他引：1
对南海西北部海区1959年全年各月所取得的浮游生物小网样品中的放射虫进行了定量研究,分析了其种类组成和分布,结果表明,所鉴定出的212种多孔放射虫主要为热带大洋暖水种,其中泡沫虫目(Spumellaria)145种,占总种数的68%,罩笼虫目(Nassellaria)67种,占总种数的32%;泡沫虫目无论在种类和数量上均较罩笼虫目占优势.研究海域的主要优势种为海绵球虫(Spongosphaera streptacantha)、钟翼盔虫(Pterocorys campanula)、四房面包虫四房亚种(Om-matartus tetrathalamus tetrathalamus)、三臂星虫(Triastrum aurivillii).该海域放射虫的全年密度分布状况变化很大,1,2月放射虫密度较小,分布范围也较小,3月起数量增多,4,5,6月是全年密度较大的月份,出现许多斑块状密集区,7,8月数量有所减少,其他月份密度也相对较小.放射虫数量变化总的趋势为春末夏初较多,秋季较少,冬季最少.放射虫的丰度和种类多样性在调查海域变化复杂,但基本趋势是从西北和北部向东南部由低逐渐升高;由海南岛周边海域和广东沿海向外海由低逐渐升高;此分布格局主要受海流、温度、盐度、深度和营养盐等环境因子的影响. 相似文献
2.
夏季风爆发前后南沙海区上层水体中的现代放射虫 总被引：2，自引：0，他引：2
利用在南沙群岛及其邻近海域获取的2002和2004年两个春季航次的28个浮游拖网站位,分析了南海夏季风爆发前后南沙海区上层水体中的现代放射虫分布特征及其年际变化。研究结果显示,南沙海区春季两个航次放射虫属种组成以热带亚热带暖水种为主要优势种,但在主要属种组成及其丰度分布上具有明显的年际差异。上层水体中放射虫丰度以及主要属种相对丰度在夏季风爆发前后的分布变化也非常明显,表明南海上层水体中放射虫对夏季风爆发有响应;在夏季风爆发后放射虫总丰度明显增高,推测夏季风爆发后的海洋环境变化可能更有利于放射虫群的发育繁盛。但对造成放射虫在夏季风爆发前后分布差异特征的直接环境因素或其形成机制还有待深入分析。研究结果还进一步证实了T.octacantha和S.glacialis可以作为热带上升流的指示种。 相似文献
3.
南海南部1百万年以来的放射虫动物群特征 总被引：3，自引：1，他引：3
定量分析了ODP184航次1143站岩心中的117个放射虫样品，得出南海南部1MaB．P．以来地层中的放射虫动物群特征如下：自1MaB．P．以来放射虫的数量分布丰度值呈现由低到高的变化趋势，并具有规律性的旋回特征，体现了1MaB．P．以来该海区放射虫动物群由贫乏向繁盛的逐步演化过程，以及海洋环境的几个阶段性变化。放射虫属种组成呈现明显的热带暖水动物群的组合面貌，优势种的组成与南海中北部海区及其它低纬度大洋相比存在一定差异，体现了该海区独特的放射虫组成特征。此外，指示温度的特征种在1MaB．P．来地层中的分布也显示了热带、亚热带海区放射虫的特殊指示作用。 相似文献
4.
南海南部活体浮游有孔虫分布特征及其影响因素初探 总被引：1，自引：0，他引：1
通过对2002年5月采自南海南部海区11个站位20个垂直分层浮游拖网样品的浮游有孔虫组成和分布特征的初步分析,发现该区表层水体中浮游有孔虫分布广泛,共鉴定属种20种,以热带暖水种占绝对优势,广适应性冷水种有零星出现。深水种Globorotalia menardii在南海南部50 m水层中广泛出现,但壳体相对较小,壳壁较薄。该区0—50m水层活体浮游有孔虫丰度范围为(6 138—64 174)枚.1 000 m-3海水,大致呈西高东低的分布趋势,在西南部浅水区和西北部上升流区丰度最高,与表层水体的营养水平密切相关。将水样浮游有孔虫分布数据与该海区23个站位表层沉积样数据进行对比分析,发现遗壳浮游有孔虫与活体的分布关系密切,虽然在种属丰度以及分布范围等方面有明显差异,但两者具有相似的优势种组合。主要差异在于水体中浮游有孔虫优势种相对丰度差异较大,易溶种Hastigerina pelagica含量较高,而遗壳中浮游有孔虫各种属分布趋向于均匀化。此外,陆源物质的释稀作用对沉积物中的有孔虫丰度分布有明显的控制作用。 相似文献
5.
对普里兹湾16个表层沉积物样品中的放射虫动物群进行了全属种鉴定和分析,共检出放射虫2目66属107种,其中罩笼虫目40属71种,泡沫虫目26属36种,前者的属种多样性和个体数量都显著高于后者。研究结果显示:普里兹湾放射虫多样性程度较低,但丰度较高,平均可达3.36万枚/g,呈现出陆架区湾口区冰架前缘的趋势,且湾西部高于东部,可能主要受研究区表层生产力、环流结构、沉积物类型和冷水团分布等海洋环境要素的影响。以Antarctissa strelkovi、Antarctissa denticulata为代表的Antarctissa group是该区最典型的优势种组合,平均百分含量高达42.43%,其分布主要受控于水体温度,其高含量具有指示冷水团分布的潜力,而该组合丰度的分布主要受环流和地形的影响;由Phormacantha hystrix、Plectacantha oikiskos和Rhizoplegmaboreale组成的特征种组合平均百分含量为12.54%,其丰度和含量的分布模式主要表征的是与环流结构有关的水团混合作用的强弱,对水深或离岸距离的指示作用并不明显。 相似文献
6.
为了解菲律宾海放射虫的区域分布特色,利用同样的样品处理方法,对菲律宾海及其邻近海域的44个表层沉积样中的放射虫进行对比分析,鉴定统计了500个属种,物种多样性较高。菲律宾海表层沉积物中放射虫的群落结构和丰度变化幅度较大,反映了菲律宾海更为复杂的区域生态环境或沉积环境;南海北部放射虫丰度非常高且罩笼虫目占据较大优势,表明南海北部区域营养盐和生物生产力较高;冲绳海槽放射虫丰度相对较低且泡沫虫目占据绝对优势,推测冲绳海槽的海底沉积环境可能不利于放射虫壳体的埋藏富集。RDA分析结果显示暖水种在冲绳海槽的分布与夏季125 m温度呈明显的正相关,可能与夏季黑潮次表层水的影响有关;在南海北部,暖水种的分布主要受冬季75 m硅酸盐和夏季200 m磷酸盐的影响控制,说明高浓度的硅酸盐可能更加有利于罩笼虫目的发育繁殖;菲律宾海主要是次表层水的环境因子影响着放射虫暖水种的分布,比如75 m冬季盐度、200 m年均溶解氧含量和125 m夏季温度。此外,菲律宾海中深层水(1000~3000 m)不同层深66个环境变量和生活于该水体中的5个冷水种的RDA分析结果,显示菲律宾海北部区域主要与1000 m硅酸盐浓度呈显著正相关,可能与富含硅酸盐的北太平洋中深层水南下进入菲律宾有关;而在菲律宾海中南部的分布则主要与1000 m硅酸盐浓度呈显著负相关,与2000 m溶解氧和2200 m磷酸盐和硝酸盐呈明显正相关,可能与具有高溶解氧低硅酸盐性质的绕极深层水由南端进入菲律宾海后,一部分水体向上进入菲律宾海中层水有关。 相似文献
7.
对冲绳海槽北部80个表层沉积样品中放射虫进行的定量研究表明，其丰度和分异度西北部低，东南部高，由西北向东南递增；从西北陆架到东南海槽放射虫分布可分为陆架低值区，海槽边缘中值区和中央高值区，放射虫的组成以泡沫虫目占绝对优势，总体面貌为热带大洋暖水动物群，沉积物中放射虫的分布与现代表层海水温度，盐度的分布和变化趋势一致，但与营养盐和实级生产力的分布呈负相关关系；同时，放射虫的分布又与研究区的海流和水团有密切关系，其中黑潮对其有控制性影响，沉积物类型极大地影响着放射虫的分布，放射虫的丰度和分异度明显地随粒度的增大和陆源物质含量的增加而减小，此外，放射虫的分岂有此理也显示了与沉积物中火山物质含量的密切相关性。 相似文献
8.
通过分析2012年4月在南海南部获取的浮游生物拖网样品,对水体中浮游有孔虫的区域分布特征及其影响因素进行了初步探讨。南海南部上层水体中共鉴定出现代浮游有孔虫19种,其中优势种为Globigerinoides sacculifer、Globigerinoides ruber、Globigerinella calida、Globigerinella siphonifera、Globorotalia menardii、Orbulina universa、Neogloboquadrina dutertrei。浮游有孔虫种属组成整体上呈现为热带-亚热带群落特征,浮游有孔虫生物丰度与西太平洋北赤道流区域的生物丰度相当。南海南部春季上层水体中浮游有孔虫整体表现为西高东低的区域分布特征,在垂直分布上浮游有孔虫集中分布在上部0～50m水层中,50m以深水体中浮游有孔虫生物丰度迅速降低。认为浮游有孔虫的分布受到温度、水体层化、初级生产力等多方面环境因子的综合作用。个别深水种(如Globorotalia menardii)出现了主要分布在0～50m水深的特殊现象。 相似文献
9.
冲绳海槽中部表层沉积物中的放射虫 总被引：7，自引：2，他引：5
1992年7月“向阳红16号”海洋调查船利用大洋50型抓斗在冲绳海槽中部（25°30’－30°N，125°－129°E）区域内获取表层沉积物样品88个。表层沉积物中的放射虫定量分析结果表明；愈近海槽放射虫的数量及属、种丰度值愈高，西侧槽坡离开槽区越远，放射虫数量及属种越渐少。而东侧槽被放射虫数量则表现了高、低值成点状分布的格局。表层沉积物中两大类放射虫的百分含量分别为泡沫虫约占87％，罩笼虫约占13％。另外根据分析结果，把本区分为3个小的沉积区：陆坡上部沉积区；陆被下部沉积区；海槽底部沉积区。 相似文献
10.
南海南部晚中新世的放射虫及其环境探讨 总被引：2，自引：0，他引：2
南海是东亚古季风产物的主要沉积盆地，保存着比陆地更加完整和连续的沉积记录。详细分析了ODP1143号钻井晚中新世的放射虫化石群，主要根据标志种Diartus petterssoni,D.hughesi和Stichocorys delmontensis等的分布特征，分别建立了南海南部晚中新世的RN6，RN7和RN8等3个放射虫化石带，并讨论了其地层年龄。探讨了以地层中放射虫的丰度变化特征等在南海南部作为东亚古夏季风活动替代性指标的可能性，初步说明东亚古夏季风可能早于8．7Ma B.P．出现，约在8．24Ma B.P.强化达到高峰，认为与印度季风的出现几乎同步或略早。 相似文献
11.
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
12.
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
13.
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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15.
《海洋学报(英文版)》2014,(9):F0003-F0003
<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, 相似文献
16.
The relationship between the flux of exotic benthic foraminiferal tests (i.e. tests which are supplied from open-sea sources alone) in a tidal inlet and that of bulk sediment was analysed, which can be expressed as two first-order linear equations. According to this relationship, in order to determine net sediment transport directions in the entrance, the test concentration in surficial sediments of the tidal basin can be compared against a ‘ critical level ’. The critical level is determined for the conditions that no net transport of bulk sediment is present within the entrance. If the observed concentration (averaged over the tidal basin) is higher than the simulated critical level, then the net sediment transport is directed to landward. This method is applied to the analysis of net sand transport at Christchurch Harbour, a tidal inlet system located in southern England. In this investigation, concentrations of exotic foraminiferal tests in the surficial sediments of the tidal basin and ebb tidal delta area were obtained from the analysis of sea-bed sediment samples. A series of probable critical levels were calculated based upon the data sets with regard to: (1) sediment discharge from the rivers; (2) magnitude of sediment discharge within the entrance during the ebb; (3) the test concentration outside the harbour; (4) the thickness of the moving layer; and (5) two parameters associated with dispersive processes. The results show that the concentration in the tidal basin sediment is higher than a number of simulated critical concentrations for representative cases. Consequently, the high level of the concentration of exotic benthic foraminiferal tests within the harbour should be explained as a result of landward net transport of sands within the entrance. 相似文献
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18.
Rahul Sharma 《Marine Georesources & Geotechnology》2000,18(3):237-250
Observations on seafloor features from subbottom profiling and seabed photography data show that the undisturbed and natural conditions before the benthic disturbance undergo a substantial change after operation of the disturber. The effects can be seen in the form of deep trenches and grooves, formed by the action of the sleds and the pumping of the sediment along its path, as well as sediment piles on either side of the track. Biological traces such as fecal coils, casts, tubes, burrows, and trails get obliterated in the areas of disturbance and resedimentation. The smooth, uniform nature of the seafloor observed in predisturbance phase shows microtopographic changes in and around the disturbed area as a result of sediment excavation and resettlement. Vertical mixing as well as lateral transport of sediment alter the geological, biological, physical, and chemical conditions on the seafloor, which need to be monitored over time to assess the process and the time taken for restoration of environmental conditions. 相似文献
19.
Vance P. Vicente 《Marine Ecology》1989,10(2):179-191
Abstract. Long-term changes in the distributional patterns of commercial sponges ( Spongia spp. and Hippospongia spp.) within the West Indian Region indicates that: 1) commercial sponges had a widespread distribution throughout the whole West Indian Region and were ubiquitous in very shallow water until about the first half of the present century; 2) they were fished commercially not only in the traditional northern Caribbean sites (Florida, Gulf of Mexico, Bahamas) but also in the Greater ( e. g. , Hispaniola, Jamaica) and Lesser Antilles; and 3) they became extinct throughout most of the Lesser Antilles ( e. g. , Puerto Rico, Vieques, St. Thomas) sometime during the first half of this century. Mortalities of spongiids within the Antilles were found to differ from other marine mortalities in that: 1) species disappeared from a large region; 2) species vanished from different habitats and depths; and 3) natural populations never recovered. Species richness patterns suggest that commercial sponge genera ( Spongia and Hippospongia ) evolved under slightly cooler elimatic conditions than those found at present, and that these extinctions occurred as a direct or indirect effect of positive thermal anomalies in sea surface and atmospheric temperatures between 1900–1950. The concept that species diversity is stable on a regional scale is questioned. 相似文献
20.
The behaviour of an axially pre-loaded cylindrical member of an offshore structure, hit by a supply ship, has been investigated. The effects of axial pre-loading on the dynamic properties of members, the extent of damage and propagation of dynamic instability in the tubular members have also been investigated. Numerical models have been validated using available experimental data from the literature although these are mostly static with no pre-loading. Axial pre-loading was found to change the dynamic characteristics of some cylindrical members quite dramatically while it had no significant effect on others. The study examined whether there was any change in the behaviour between local and global modes when the loading was dynamic rather than static. The effect of damping on the dynamic instability of axially pre-loaded tubes under lateral dynamic loads was also studied. It was observed that for some geometries the quasi-static response can be used to define the boundary between bounded and unbounded dynamic responses. The main contribution of this study, compared with previous investigations reported in the literature, is that both pre-loading and dynamic effects have been included. 相似文献