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Recruitment of early life stages into estuaries is an integral part of the life cycle of many marine fish species. Although estuaries are naturally environmentally dynamic, they also are subject to anthropogenic disturbances, including land use and climate change, which may affect recruitment. Rhabdosargus holubi is an endemic marine-spawning species predominantly associated with freshwater-rich estuaries which serve as nursery areas for postflexion larvae and juveniles. This study assessed the effect of environmental variables on the dynamics of recruitment of R. holubi larvae and juveniles into the Swartkops and Sundays estuaries, South Africa. Over a period of two years, fyke nets were set at each estuary mouth to monitor movement into the estuaries at each tidal phase over a 24 h cycle during two sampling sessions per season. Rhabdosargus holubi larvae recruited into estuaries primarily in summer and autumn and during the ebb tide at night, while juvenile movements showed no pattern. Salinity, turbidity and temperature were significantly important factors affecting R. holubi recruitment, with pH having no significant effect. Turbidity and salinity are affected by rainfall and freshwater abstraction which may thus influence recruitment. Rhabdosargus holubi is dependent on estuaries, so a combination of future changes in turbidity, salinity and temperature due to predicted climate change may place populations at risk. 相似文献
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Anomozamites (Bennettitales) from Middle Jurassic Haifanggou Formation,western Liaoning,China 总被引:1,自引:0,他引:1
The Middle Jurassic Hangfanggou Formation is well exposed in Shangsanjiao and Xiasanjiao villages area,Baimashi town of Huludao,western Liaoning,China.Recently,abundant fossil plants were collected from the Hangfanggou Formation.One new species,Anomozamites sanjiaocunensis sp.nov.(Bennettitales),is described in this study.This is the first report of the genus Anomozamites from the Haifanggou Formation based upon the leaf morphology and epidermal structures.The discovery of the new species extends significantly the stratigraphic and geographic distribution of Anomozamites in the Middle Jurassic.It also shows that Anomozamites was a common member of Bennettitales once lived in the Middle Jurassic warm temperate region.The new species also improves the knowledge on understanding the leaf morphology,epidermal features and the diversity of Anomozamites during the Middle Jurassic.The epidermal characters of the new species and its associated plants reveal that the plants grew in a warm and moderately humid environment in the warm temperate zone.The presence of some deciduous plants,such as ginkgoaleans,czekanowskialeans and conifers,indicate the climate with seasonal fluctuations in temperature. 相似文献
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鹿乡断陷近年来虽在油气勘探方面取得了一系列成果,但该区存在多物源方向交汇、沉积体系划分不清晰;而经典的物源分析方法操作复杂,可靠性差。笔者应用统计学方法,对研究区重矿物的相对含量进行聚类分析,结合研究区砂岩等厚图,对鹿乡断陷双阳组各段的物源方向进行分析,结果表明:在双阳组一段沉积时期,研究区存在西南、南部和东部3个物源方向;在双阳组二段沉积时期,研究区存在东部、南部、西南和西北4个物源方向;在双阳组三段沉积时期,研究区存在东部和西北部2个物源方向。双阳组沉积时期,西北和南部方向物源的沉积物供给呈现"弱--强--弱"的变化特点,东部方向物源的沉积物供给不断减弱。沉积体系的规模受控于沉积速率。 相似文献
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从北极王湾地区湖泊沉积物中分离出的菌株AFN2001,其代谢产物对金黄色葡萄球菌有明显的抑制作用,抑菌圈直径达23 mm,对大肠杆菌和绿脓杆菌没有抑制作用。为了确定AFN2001菌株发酵获得最多的活性物质,对单因素确定的营养因素淀粉、黄豆浸出物、蔗糖和NaNO3及另外的MgSO4、K2HPO3和水质进行7因素3水平正交优化实验。对结果进行直观分析及方差分析,发现NaNO3对发酵液活性的影响最大,其次依次为淀粉、K2HPO3、MgSO4、黄豆浸出物、蔗糖和水质对发酵液活性的影响;并找出产生活性物质的最佳组合。确定优化培养基(淀粉为10 g、蔗糖为10 g、黄豆浸出物为6 g、MgSO4为0.5 g和自来水为1 000 mL)和优化发酵条件(发酵温度为28℃、起始pH值为6.0和装液量为50%)。利用优化培养基和优化发酵条件发酵的菌株AFN2001,其发酵液的抑菌活性是基础培养基发酵液的1.6倍。 相似文献
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A scanning t-test algorithm for detecting multiple time-scale abrupt changes in the level of a time-series was used to analyze an 8000 year time series of annual precipitation which was reconstructed from tree rings for the Nevada Climate Division 3 in the western USA. The tree ring samples were gathered from eight states in the southwestern USA. Twenty-two change-points were identified by the algorithm and these were used to partition the tree-ring series into twenty-three relatively Wet/Normal/Dry episodes. These twenty-three episodes were collaborated by a coherency analysis of abrupt changes between the precipitation reconstruction series and the TIC/δ18O records from cored sediments of Pyramid Lake in Nevada, and by comparison with published results from related studies. These episodes were also compared with studies of the global climate change and with records of climate change in China during the same periods. The results suggest that the precipitation reconstruction series is quite valuable for climate-change research on multi-centurial time-scales in the western USA, and that the scanning t-test and coherency detection algorithms may have a wide use for detecting multiple time-scale abrupt changes in a long time series.As the TIC and δ18O record series are high resolution with unequal sampling intervals ranging between 3 and 14 years, a new algorithm was developed to deal with the unequal time intervals in the series. 相似文献
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如何在LINUX下并行运行数值模式 总被引:2,自引:0,他引:2
针对运行数值模式的目的,着重介绍Linux系统的安装、编译和并行环境的建立,以及相关软件的编译安装。所用软件都可以通过Internet网获得,十分适合基层台站建立并行计算机系统,解决计算机资源和实际业务发展的矛盾,为精细化预报提供基础,同时也适合科学研究。 相似文献