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1.
福建近海主要经济渔业生物营养级和有机碳含量研究   总被引:2,自引:0,他引:2  
卢振彬  黄美珍 《台湾海峡》2004,23(2):153-158
本文研究了福建近海52种鱼类、6种虾类、4种蟹类、1种虾蛄和4种头足类的食性和营养级及其有机碳含量。结果表明:营养级以鱼类最高,为2.1~3.7级,平均2.65级;头足类为2.04~2.88级,平均2.60级;蟹类2.38~2.73级,平均2.58级;虾类最低,为1.64~2.21级,平均1.96级.干样有机碳含量百分率也以鱼类最高,为33.0%~76.2%(m/m),平均46.25%(m/m);头足类为27.80%~46.16%(m/m),平均40.24%(m/m);虾类为30.60%~38.40%(m/m),平均34.90%(m/m);蟹类最低,为25.00%~30.78%(m/m),平均28.24%(m/m),鲜样有机碳含量百分率还是以鱼类最高,为4.80%~29.55%(m/m),平均13.75%(m/m);蟹类为8.90%~12.68%(m/m),平均10.74%(m/m);虾类为6.97%~11.53%(m/m),平均9.55%(m/m);头足类最低仅为7.38%~8.52%(m/m),平均7.95%(m/m),干样有机碳含量百分率和鲜样有机碳含量百分率与营养级均成正相关,但前者的相关性高于后者。  相似文献
2.
In estuarine sediment flats benthic macroinvertebrates are intensively consumed by a variety of predators, such as aquatic birds and nekton (mostly fish and crustaceans). However, there is still a lack of conclusive studies that evaluate if this predation has a relevant impact on the populations of those invertebrates, which are a key element of the estuarine food chain. In the Tagus estuary we experimentally tested and quantified the impact of predation on the polychaete Hediste diversicolor, one of the most important prey for a variety of predators in many estuaries. Using an exclusion experiment, we compared the seasonal variation in the densities of H. diversicolor from February to November in sediment plots (1) available to both bird and nekton predators, (2) just to nekton, and (3) without predators. We also followed changes in the abundance of potential predators throughout the study. The lowest densities were systematically observed in the plots accessible to all predators, followed by those which excluded just birds, and finally by those that excluded all predators. The exclosures were in place for 9 months, at the end of which the average density of H. diversicolor in the plots protected from all predators was eight times greater than in those without any protection. These results demonstrate that predation had a major impact on the densities of H. diversicolor. The relative importance of bird and nekton predation varied along the study, and this seems to be determined by different peaks of abundance of the two types of predators. However, when present in high densities, birds and nekton seem to have a similar impact on H. diversicolor. Our results suggest that predation is a key factor on the population dynamics of H. diversicolor. In addition, the levels of predation that we observed suggest that this polychaete can be a limited resource, and this could have major ecological consequences for predators for which it is a key prey.  相似文献
3.
The epipelagic and mesopelagic nekton communities of the northern California Current have been sampled somewhat continuously over the last four decades with bottom and pelagic trawls, small midwater trawls, and purse seines. We review the zoogeography and community and environmental associations of the dominant pelagic micronekton and nekton species in this region with a view to understanding their role in this dynamic marine ecosystem. As is typical of many upwelling eastern boundary current regions, the pelagic biomass is dominated by a few species that fluctuate dramatically through time. The abundance trends of pelagic nekton caught in this region demonstrated large-scale ecosystem changes about the time of the regime shifts of 1976/77 and 1989 and possibly another beginning in 1999. The rapidity of the changes in composition indicates that the response was due to a change in migration or distribution patterns as opposed to recruitment patterns. The 1989 regime shift led to a dramatic increase in sardine and a decrease in anchovy populations. The most pronounced interannual signals were attributed to strong El Niño/Southern Oscillation (ENSO) conditions in 1983 and 1998 that altered the latitudinal ranges and proximity to the coast of many pelagic species. Variations in abundance and cross-shelf distribution patterns were noted for both pelegic nekton and micronektonic from surveys off California, Oregon, and Washington.  相似文献
4.
Fluctuations and Variations in Coastal Marine Environments   总被引:1,自引:0,他引:1  
Abstract. The manifold aspects of variability of coastal marine ecosystems are reviewed, with special reference to the response of species and communities. Fluctuations are defined as recurrent modifications in community structure, for instance due to seasonality, whereas variations are defined as changes permanently leading from a given community to a different one. Both patterns are described and linked to the interaction between life history traits and environmental factors. Resting stages are proposed to play a still underestimated role in the dynamics of coastal communities, especially for plankton. Rare species are considered as an essential constant of communities, being the source of potential variation and alternance in the contribution to the standing biomass.  相似文献
5.
在流沙湾湾口设置双桩张纲张网对海湾游泳动物进行16次采样调查,结果表明:流沙湾有游泳动物161种,隶属3纲13目55科,其中:鱼类9目43科100种,虾类2目5科32种,蟹类1目4科20种,头足类2目3科9种,鱼类种类8月初最多,1月初最少;虾类种类10月底最多,1月底最少;蟹类种类8月初最多。16次采样共捕获虾类604121尾,1024kg;鱼类201339尾,1344.7kg;蟹类15115尾,49.5kg;头足类947尾,9.9kg。游泳动物生物量最高值出现在4月底、5月初和8月底,最低值出现在1月底和12月底。游泳动物优势种依次为刀额新对虾、沙栖新对虾、多鳞鱚、近缘新对虾、短棘银鲈、孔鰕虎鱼、中型新对虾、短吻鲾、刀额仿对虾、黑鳃梅童鱼、角突仿对虾、东方箬鳎、黄斑蓝子鱼和银光梭子蟹。流沙湾游泳动物丰富度指数变化较大,多样性指数、优势度值、均匀度值变化不大。  相似文献
6.
根据2007~2008年间在厦门海域开展的游泳生物周年季节调查数据,分析了厦门海域游泳生物种类组成、数量分布特征和季节变化,结果表明,厦门海域游泳生物种类236种,其中鱼类153种(软骨鱼类11种,硬骨鱼类142种),隶属于16目61科108属;甲壳类71种,隶属于3目21科35属;头足类12种,隶属于3目4科5属12种.游泳生物平均密度指数为1 337ind/(网.h),平均生物量指数为19.560 kg/(网.h).生物量优势种为叫姑鱼(Johnius belengerii),密度优势种为鹿斑鲾(Leiognathus ruconius).游泳生物生物量指数的季节变化为夏季〉冬季〉秋季〉春季,密度指数的季节变化为夏季〉秋季〉春季〉冬季.同时对厦门海域游泳生物多样性特征进行分析表明,不同海域生物多样性变化特征存在明显差异,多样性指数(H')由东向西逐步递减,即大嶝海域〉东部海域〉九龙江口及厦门港海域〉同安海域〉厦门西港海域.并讨论了多样性特征和主要优势种的区域分布特征,结果表明,受河口区复杂环境条件的影响,该海域游泳生物季节群聚优势种较为明显.游泳生物多样性特征的变化是由于各季节主要种类的优势度不同引起的.  相似文献
7.
刘勇  马超  张澄茂 《台湾海峡》2012,31(4):517-522
根据2009年5月单船底层拖网和定置三重刺网作业调查资料,分析研究了诏安湾口海域春季游泳动物的种类组成、生物密度指数分布及种类多样性等.结果表明:调查海域游泳动物有48种,其中鱼类为26种,占54.2%;甲壳类为16种,占33.3%;头足类为6种,占12.5%.相对重要性指数(IRI)大于500的有4种,分别为多鳞鱚(Sillago sihama)、白姑鱼(Argyrosomus argentatus)、日本蟳(Charybdis japonica)、哈氏仿对虾(Parapenaeopsis hardwickii);种类丰富度指数范围为1.412~3.419,平均值为2.291;Shannon-wiener多样度指数范围为0.800~2.264,平均值为1.568;种类均匀度指数范围为0.411~0.836,平均值为0.659.总体来看,诏安湾口海域生物量处于较低水平,需要开展增殖放流,通过海洋牧场与人工鱼礁建设,以逐步恢复渔业资源.  相似文献
8.
根据2014年5月及8月在天津海域进行的底拖网调查资料, 对该海域游泳动物组成特征进行了初步研究。结果表明, 在该海域共捕获游泳动物36种, 平均资源密度为126 297.13 个/km2 和1 494.40 kg/km2 。以个体密度计算群落多样性, Shannon-Wiener种类多样性指数H′平均为1.803, Margalef种类丰富度指数d平均为0.592, Pielou种类均匀度指数J平均为0.537。资源密度及物种多样性, 8月均优于5月。优势种为口虾蛄, 重要种为火枪乌贼、日本 、斑 、六丝钝尾虾虎鱼。天津近岸海域游泳动物渔业资源呈现出低质化的趋势。  相似文献
9.
依据2011年4月、7月和11月象山港水域桁杆拖网和单拖网渔业资源定点调查资料,对象山港水域游泳动物群落的功能群组成及功能群多样性特征进行了系统研究。依据摄食习性,本文将调查海域出现的96种游泳动物划分为7个功能群,其中底栖动物/游泳动物食性、游泳动物食性、底栖动物食性和腐屑食性功能群是该水域的优势功能群。相似性分析检验结果显示:不同季节象山港游泳动物群落的功能群结构保持相对稳定,不存在显著性季节差异。4月、7月和11月该水域游泳动物群落的功能群多样性均值分别为1.303、1.261和1.185,亦未呈现显著性季节差异。功能群多样性指数与大个体生物(体重大于50g)的总重量资源密度显著正相关;功能群多样性与物种多样性的关系可用斜率为0.463、截距为0.266的线性方程进行描述,这表明该水域物种多样性的大量丧失可能引起功能群多样性的降低。象山港水域部分功能群所含物种数明显偏少,冗余度较低,在强大的外界干扰下,某些重要物种的衰退可能将使该水域功能群多样性显著降低。  相似文献
10.
台湾海峡是连接东海和南海的过渡区域,拥有独特的水文地理环境和特殊的生物群落组成。为了分析台湾海峡游泳动物群落的空间结构及其季节变化,2006-2007年在该区域进行了四个季节的底拖网调查。分析结果表明,在该海域存在两个种类组成差异明显的群聚类型,组内平均相似性在39.38到74.20之间。对其优势种类的分布及变化分析表明,该海域的游泳动物群落结构存在明显的季节变化,莆田至厦门之间的海域可以认为是两个不同群聚类型的混合区域。对群落结构与环境因子的关系分析表明,温度在冷季(冬季和春季)是群落结构最重要的影响因素,22.5℃和17℃分别是春季和冬季两个群落类型的分界线。在暖季(夏季和秋季)对群落结构最重要的影响因素是水深,但是其关系也不显著,相关系数在0.264至0.399之间。游泳动物群落结构的季节变化反应了台湾海峡水团的变化,在夏季随着暖流的强盛,南部近岸群落几乎可以扩展至整个台湾海峡,而在春季和冬季,随着浙闽沿岸流的强盛南部近岸群落的分布范围逐渐向南退缩。极端天气、全球变暖以及人类活动等短期和长期的因素都会影响游泳动物群落结构,但是其影响机制和程度还需要进一步的研究,我们对台湾海峡游泳动物群落结构及其季节变动的分析可以为今后的研究提供本底数据和资料。  相似文献
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