Influence of mesoscale oceanographic processes on larval distribution and stock structure in jackass morwong (Nemadactylus Macropterus: Cheilodactylidae)     

Bruce  B. D.; Evans  K.; Sutton  C. A.; Young  J. W.; Furlani  D. M. 《ICES Journal of Marine Science》2001,58(5):1072-1080

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Internal tidal bore warm fronts and settlement of invertebrates in central Chile     

Cristian A. Vargas  Diego A. Narvez  Andrea Piones  Roberto M. Venegas  Sergio A. Navarrete 《Estuarine, Coastal and Shelf Science》2004,61(4):603-612

We studied the occurrence of large high frequency temperature fluctuations and their potential association with settlement of intertidal invertebrates during the spring/summer period 1999/2000 at Las Cruces, on the coast of central Chile. Our results showed the existence of internal tidal bores, characterized by sharp drops in water temperature at the surface and near the bottom, and subsequent temperature increases, which occurred with a semidiurnal periodicity. Measured currents support the hypothesis of alternating onshore and offshore movement of warm-water fronts. The frequency of the events varied through the summer and their amplitude seems to be modulated by onshore winds. The strongest events were observed when strong onshore winds occurred in late afternoon hours and the entire water column showed a semidiurnal temperature signal. Highest values of chlorophyll concentration in the intertidal zone and daily settlement of bivalves, gastropods and crustaceans were observed at times when conditions were favorable for occurrence of internal tidal bores. Results suggest that internal tidal bore warm fronts could play an important role in the transport of neustonic larval invertebrates and the delivery of phytoplankton to at least some intertidal sites along the coast of Chile.  相似文献   

Preface: land-use impacts on aquatic ecosystems - tribute to John Quinn     

Scott Larned  Kevin Collier  Clive Howard-Williams 《新西兰海洋与淡水研究杂志》2020,54(3):305-307

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Significance of gabbronorite occurrence in the crustal section of the Semail ophiolite     

Boudier  Françoise  Godard  Marguerite  Armbruster  Catherine 《Marine Geophysical Researches》2000,21(3-4):307-326

The eastern end of the Haylayn massif exposes a complex paleoridge structure interpreted as the tip of a northwestward propagating segment (Nicolas et al., this issue). The area, revisited from a petrostructural and geochemical viewpoint, offers the most documented exposures of the association of olivine gabbros and gabbronorites in Oman (Juteau et al., 1988). Gabbronorites were injected while the main gabbro unit was deforming in the magmatic state. Both units do not differ chemically, except for the SiO₂ enrichment of the orthopyroxene-rich gabbros relative to olivine-gabbro. In addition, they display the same trace element signature, which implies the same parent magma for both units. The extension of the stability field of orthopyroxene is assigned to increase of oxygen fugacity due to hydration. The source of hydration is the ridge axis hydrothermal circulation, suggesting hydrothermal/magma interaction at temperatures above the gabbro solidus. The distribution of gabbronorites at the scale of the entire ophiolite suggests a relation with ridge tectonics where high-T conditions of hydrothermal-magmatic interaction are met. Such conditions are met when propagating segments rotate the structures of the dying magma chamber.  相似文献   

Abrupt axial variations along the slow to ultra-slow spreading centers of the northern North Fiji Basin (SW Pacific): Evidence for short wave heterogeneities in a back-arc mantle   总被引：1，自引：0，他引：1  

Erwan Garel  Yves Lagabrielle  Bernard Pelletier 《Marine Geophysical Researches》2003,24(3-4):245-263

This study presents results of surveys conducted along the slow to ultra-slow spreading axis of the Northern North Fiji Basin (NNFB), including the Hazel Holmes, Tripartite and South Pandora Ridges, and the newly discovered Futuna and North Cikobia spreading centers. Spreading segments along these axes display highly contrasted axial morphologies, ranging from a rift valley to a prominent axial high. In some places, abrupt inversions of topography are observed between neighboring segments. Detailed analyses of bathymetry and backscatter maps reveal that axial highs are spotted with numerous coalescent volcanoes forming features ranging from irregular terrains to well-organized ridges. The volcanic edifices are distributed over a wide neovolcanic zone, which corresponds to the axial relief, suggesting on important contribution of volcanism to the relief construction. Comparisons between various ridge-shaped segments reveal that axial volcano-tectonic patterns are directly related to the local magma production and delivery, in a context of tectonic extension related to plate divergence, and suggest that coalescent volcanoes are fed from multiples short-lived and unconnected magma lenses. In the competition between horizontal and vertical accretion of oceanic crust, the spreading centers of the NNFB represent a special case where lava production is locally high enough and spreading rate is low enough to allow prominent axial highs to develop. The along axis morphologic variability is related to intermittent volcanic activity that may result from rapid temporal and spatial variations in the distribution of upper mantle convection cells below accretion centers, superimposed on the regional thermal anomaly located under the whole basin.  相似文献   

莱州市近岸海域水动力状况分析与海洋环境的合理利用   总被引：1，自引：0，他引：1  

赵可胜  王学昌  孙长青 《中国海洋大学学报(自然科学版)》1994,(Z1)

建立莱州市近岸海域潮流数值模型,并在此基础上建立了拉格朗日余流模型。结合在主要入海排污口进行的数值跟踪,对莱州市近岸海域的物理自净能力进行了分析。并对海洋环境的合理利用进行了探讨。  相似文献   

Spatial variation of nutrients and primary productivity in the Rufiji Delta mangroves,Tanzania     

A Minu  JF Machiwa  S Pamba 《African Journal of Marine Science》2020,42(2):221-232

Determinations of spatial and temporal variations in organic matter and nutrient dynamics in water and sediments are crucial for understanding changes in aquatic bodies. In this study, we (i) determine the spatial dynamics of dissolved inorganic nutrients, during the transition from the dry to the rainy season, and (ii) provide future productivity predictions for the Rufiji Delta mangroves, Tanzania, based on the input of various nutrients. Water samples were collected from six locations, three times per year between April 2012 and January 2014, and analysed for dissolved nutrients, total organic and inorganic carbon, chlorophyll a, chlorophyll b and total carotenoids. The prediction of future net primary productivity in the Rufiji mangroves was undertaken using the software STELLA. The mean nutrient concentrations were of the order: nitrate > phosphate > ammonium > silica > dissolved organic carbon. The study revealed that high nutrient concentrations occurred in the northern part of the Rufiji Delta as a result of anthropogenic influence in the watershed. Modelling of nutrient inputs into the delta indicated enhanced primary productivity, which is expected to increase the vulnerability of water quality in the near future due to eutrophication.  相似文献   

连云港近岸海域物理自净能力研究及水质预测——Ⅰ.西大堤工程对潮流场的影响     

王学昌  孙长青  赵可胜 《中国海洋大学学报(自然科学版)》1994,(Z1)

采用有限差分解法,建立了连云港近岸海域二维固定边界和变边界潮流数值模型。分别对现状流场和西大堤建成后的流场进行计算和预测。得出了潮波图,潮流椭圆图,最大流速分布和不同时刻的流场图,计算结果与实测值吻合良好。  相似文献   

数字式主动声呐研制的初步探索     

许鹭芬  毛岱山 《台湾海峡》2005,24(4):463-468

首先介绍数字式主动声呐的优点及实现上的特殊困难．采用时间相关积累信号处理方法，可以克服海洋背景噪声和船只自噪声的干扰，并具有强烈的抗起伏性能．在垂直向下探测或短距离、高频探测等特殊条件下，依混响的衰减规律，由微机组成精确的灵敏度时间控制网络，可以抑制混响的影响，并大大地简化了目标识别的难题．回声测深仪、垂直探鱼仪及本文介绍的浅海航行暗礁障碍探测仪的研制和海上实验，说明了这个结论．  相似文献   

杭州湾跨海大桥非通航孔桥跨比选方案的模型试验   总被引：1，自引：0，他引：1  

曾剑  夏润贤  熊绍隆  韩海骞  俞月阳 《海洋学研究》2002,20(4):64-69

利用水平比尺与铅直比尺均为100的正态断面模型,研究了杭州湾跨海大桥非通航孔两个桥跨的桥墩对水流的影响。方案一为50m跨径的桥墩方案,在模型中布置了7跨6个桥墩;方案二为70m跨径的桥墩方案,在模型中布置了5跨4个桥墩。在桥位附近的不同距离处还布设了5条断面16个流速测点和4个水位测站,以反映不同桥墩对周围环境的影响,结果表明,两个方案的流速变化率均在9%以内,水位壅高值在0.17m以内。相对而言,方案一对水流影响稍大,但两方案的流速变化率最大差异仅为1.6%,水位变化最大差异为0.03m,与杭州湾跨海大桥整体模型的试验结果基本一致。由于两个方案对水流的影响均在同一量级,且50m跨径的桥墩可以节省巨额投资,又便于施工,因此,建议杭州湾跨海大桥的非通航孔采用50m跨径。  相似文献