The influence of light availability and predatory behavior of the decapod crustacean Nephrops norvegicus on the activity rhythms of continental margin prey decapods     

Jacopo Aguzzi  Nixon Bahamon  & Leonardo Marotta 《Marine Ecology》2009,30(3):366-375

The day–night cycle is one of the strongest geophysical cycles modulating species' behavioral rhythms. However, in deep-water continental margins, where light intensity decreases over depth, interspecific competition may alter behavioral responses to day–night cycles. The burrowing decapod crustacean Nephrops norvegicus is a large-size predator in benthic communities, exerting despotic territorial behavior. In this study, we analysed how the effect of light intensity cycles on decapod behavioral rhythms is reduced as one moves from shelves to slopes. In the Western Mediterranean, the predatory behavior and interspecific competition for substrate use of Nephrops increases moving from the shelf (100–110 m) to the slope (400–430 m). Vector fitting and generalized additive models were used to assess the effect of light intensity and behavioral rhythms of N. norvegicus on the temporal variation of prey decapods co-occurring in trawl tow catches carried out on the shelf and the slope during October 1999 and June 2000. The combination of diel variations in light intensity and N. norvegicus abundance influences the activity rhythms of prey decapods in a depth- and seasonal-dependent manner. Light modulation is stronger on the shelf and weaker on the slope, where Nephrops population size is greater. Although present regression analysis does not necessarily imply a direct cause–effect relationship between rhythms of predators and prey, we suggest that Nephrops alters the temporal patterning in the behavior of its prey on the slope, where light intensity is reduced. This alteration is stronger in endobenthic species than in benthopelagic species; the former rely on bottom substrate for the expression of behavioral rhythms, experiencing stronger interspecific competitions with Nephrops at time of activity.  相似文献   

春晓气田泥岩垮塌测井数据校正及应用     

谢月芳  陈敏 《海洋地质译丛》2009,(4):73-76

由于存在部分泥岩井眼垮塌,东海春晓气田测井曲线砂泥岩阻抗部分叠置。针对这一现象,采用未垮塌段泥岩伽马与密度拟合关系校正垮塌段泥岩密度,声波时差经本区伽德那公式拟合后求取。通过泥岩垮塌测井数据校正前后对比、直方交会、岩石物理、正演及反演效果分析,认为校正后的测井数据比较真实地反映垮塌段扩径泥岩地层特征,储层与围岩波阻抗差异明显,为储层反演、砂体空间展布分析提供了有力依据。  相似文献   

港珠澳大桥水下结构物的多手段探测   总被引：1，自引：0，他引：1       下载免费PDF全文

洪四雄  刘庆东  陈一超  张春添 《海洋测绘》2009,29(5):71-73

介绍了利用侧扫声纳、浅地层剖面仪和磁力仪开展港珠澳大桥水下结构物的探测方法和过程,并将探测的结果与调查收集的资料比较,分析水下结构物的分布情况,不同探测方法得出的结果也可以相互印证。  相似文献   

高分辨率遥感影像在岩墙地质体信息提取中的应用   总被引：5，自引：0，他引：5  

张自力  秦其明  曹宝  张玉虎  李百寿 《地理与地理信息科学》2007,23(3):15-18

高分辨率遥感影像可明显表现地物的几何结构和纹理特征,从而使得在较小空间尺度上观察地物细节变化、进行大比例尺遥感制图成为可能。利用高分辨率QuickBird遥感影像,对新疆巴楚县麻扎尔塔格山地区的岩墙进行计算机辅助地质解译,共获得1227条岩墙。结合GIS空间分析方法获得了解译岩墙长度、走向分布等特征。结果表明:该地区76%的解译岩墙走向为NNW(135°~180°);QuickBird能够满足1∶2.5万地质调查的要求;通过地质分析综合解译结果获得了麻扎尔塔格岩体内部存在发育岩墙、岩墙形成应晚于内部的正长岩体的新认识。探讨并验证了高分辨率遥感影像在中小规模地质体解译中的可行性和有效性。  相似文献   

混合物介电常数的新公式   总被引：2，自引：0，他引：2  

李剑洁 《地球物理学报》1989,32(6):716-719

本文给出了混合物介电常数的新公式并用一个例子验证了新公式的有效性.此公式可以代替现有的公式应用到测井解释中,以提高解释的精度.  相似文献   

Areal extent of the 1988 flood in Bangladesh: How much did the satellite imagery show?     

Harun Rasid  M. A. H. Pramanik 《Natural Hazards》1993,8(2):189-200

This paper presents the methods and results of visual interpretation of satellite imagery for estimating areal extent of the 1988 flood in Bangladesh. The main limitation of this method was that cloud-free images were not available for the peak flood period in the first week of September. Relatively cloud-free images on three selected dates in the last three weeks of September showed that areas of inundation on those dates ranged from 44000 to 60000 km² ± 5% (31 to 42% of Bangladesh). The Government of Bangladesh official estimates of the areal extent of flooding were tentative in nature, since these were based on a choropleth map of relative proportions (percentages) of flooding in different parts of the country. The official estimate of the maximum extent of flooding was 82000 km² (57% of Bangladesh), i.e. 15 to 26% larger than the area shown on satellite imagery. The actual extent of flooding was certainly larger than the estimates from satellite imagery but, perhaps, smaller than the official estimates, since a reduction of 15 to 26% of flood area in one to three weeks seemed unlikely. An alternative method of mapping flood-affected areas by using newspaper-interpreted data was attempted, but the method had limited values because of reporting bias.  相似文献   

深反射地震资料处理和解释的初步研究   总被引：3，自引：0，他引：3  

徐明才  高景华  胡振远 《物探与化探》1995,19(5):360-365,367,368

深反射地震资料处理的关键是从干扰背景中提取和增强深层弱有效信号,提高剖面的信噪比和分辨率.深反射地震剖面的解释要着眼于大的地质构造运动和成因,运用地质规律进行综合地质解释.在解释中,通过分析和研究某些相干干扰波的形成和特点,有助于对深反射地震剖面进行可靠的地质推断解释.  相似文献   

Propagation and Structural Interpretation of Non-Plane Waves     

E. Wielandt 《Geophysical Journal International》1993,113(1):45-53

  相似文献   

铀矿层真实厚度的确定和最佳测井点距          下载免费PDF全文

秦积庚  谭庆江 《地球物理学报》1990,33(4):468-479

本文讨论了最佳测井点距的选择原理,其最佳值大致为8-12.5cm.并从原理上分析了矿层解释厚度增大的主要原因:根据离散测量值所作的分层解释结果必然导致矿层解释厚度的增大.大量的模型测量结果完全证实了理论分析的正确性,并且还提出了合适的解决办法.  相似文献   

Magnetic interpretation of pairs of sheets and their equivalence to dykes     

S. K. G. Krishnamacharyulu  Bh. V. V. Gopalarao  I. V. Radhakrishna Murthy 《Pure and Applied Geophysics》1990,132(4):719-731

Magnetic anomaly profiles over two thin sheets separated by a small distance resemble those of dykes andvice versa. Interpretation of anomalies over a pair of sheets based on the magnetic properties of dykes predicts a dyke whose centre lies midway between the positions of the sheets. The dyke, on the other hand, is magnetically equivalent to a pair of sheets, both lying at the same depth and having the same magnetization.The magnetic anomalies due to a pair of sheets can be interpreted by framing linear equations between the anomalies and their distances measured from an arbitrary reference. Application of this method to anomalies of dipping sheets with a finite depth extent is indicated.  相似文献