Annual stability in the use of coves near inlets as settlement areas for winter flounder (Pseudopleuronectes americanus)     

Mary Carla Curran  Kenneth W. Able 《Estuaries and Coasts》2002,25(2):227-234

Coves near an ocean inlet in Little Egg Harbor in southern New Jersey may be important settlement areas for winter flounder (Pseudopleuronectes americanus), based on the high abundance of small postlarval individuals. During 1994–1996 we sampled in two coves and adjacent areas of this same estuary to determine if this pattern was annually consistent. Collections in spring and early summer indicated that small, recently-settled winter flounder (10–45 mm TL) were abundant in the coves from May to mid-June in every year with maximum mean densities ranging from 1.5–2.5 ind m⁻² and that these same size individuals were never collected at these densities in other habitats in the same estuary. Densities in the coves declined soon after settlement, usually by late June to early July in each year. In order to determine factors that may influence these high settlement rates we examined aspects of habitat quality by determining habitat-specific growth rates in cages for recently-settled individuals (17.5–38.3 mm TL) both inside and outside the coves during 1995. These rates (3.7–9.1 wt d⁻¹) overlapped those of other estuarine habitats (3.1–10.5 wt d⁻¹) suggesting that habitat quality, based on growth, does not differentiate the coves from other potential settlement habitats. Mark/recapture experiments for recently settled individuals (range 13–70 mm TL) in 1994 and 1996 had low recapture rates (1% in both years) suggesting that dispersal from the cove occurred soon after settlement. This pattern confirms that these coves are used as settlement areas but they are probably not used as nurseries because winter flounder, at least in this system, do not settle and stay and, as a result, use other habitats as primary nursery areas.  相似文献   

Viral-like particles (VLPS) in the alga,Aureococcus anophagefferens (pelagophyceae), during 1999–2000 brown tide blooms in Little Egg Harbor, New Jersey     

Mary Downes Gastrich  O. Roger Anderson  Elizabeth M. Cosper 《Estuaries and Coasts》2002,25(5):938-943

We assessed the presence and quantified the intracellular virus-like particles (VLPs) in natural populations ofAureococcus anophagefferens during the 1999–2000 brown tide blooms that occurred in New Jersey coastal waters. From displayed a wide range of ultrastructural changes from apparently healthy cells to those showing late stages of production of VLPs. VLP-infected cells usually had an electron dense plasma membrane and lacked the typical exocellular polysaccharide layer (EPS). The VLPs were similar in size (c. 140 nm) and morphology to those initially reported in natural populations ofA. anophagefferens and to brown tide viruses (BtVs) which were previously isolated and inoculated into laboratory cultures ofA. anophagefferens. VLP-infectedA. anophagefferens were found consistently throughout the brown tide blooms in both years in Little Egg Harbor. Percentages of VLP-infected cells were 8.1% at the beginning of a bloom, which decreased to less than 2% at the height of the blooms during both years, and increased at the end of the 2000 bloom to 2.5%. While these percentages appear low, the estimated VLP infection rate ofA. anophagefferens cells, which ranged from 0.83%–50% of the standing population, is comparable to other studies.  相似文献   

Inverse Models: A Necessary Next Step in Ground-Water Modeling   总被引：24，自引：0，他引：24  

Eileen P. Poeter  Mary C. Hill 《Ground water》1997,35(2):250-260

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水在橄榄石中溶解度研究的固体传压高温高压实验方法     

孙天泽  张佩春  徐实昆  白武明  刘斟 《地球物理学进展》1997,(4)

人们关注地球深部水对地球介质的力学和物理性质影响．以往实验研究大都用气体设备在几百MPa的低压力下进行的．为实现深部高压条件，本文用固体传压技术在1000-1300℃；1．0～2．0GPa（相当上地幔）温压条件进行橄榄石晶体内水溶解度实验研究．实验表明，固体传压技术用于晶体“含水”实验研究是一种有效方法；研究证实，与低压实验一样，高压下水赋存在橄榄石晶体中仍以H离子作为“杂质”进入晶体缺陷为主要形式，并发现水的溶解度与实验压力相关，  相似文献   

Periodic anoxic shelf in the Early-Middle Ordovician transition: ichnosedimentologic evidence from west-central Utah, USA     

GONG Yiming  Mary L.Droser 《中国科学D辑(英文版)》2001,44(11):979-989

Ichnosedimentologic evidence of periodic anoxic shelf in the Early-Middle Ordovician transition includes lower ichnodiversity, shallower bioturbation and burrowing depth (<4 cm), rare domichnia, tinyChondrites occupying shallower or shallowest tiering, widely distributed nodules of limonite pseudomorphs after pyrite, occurrence of trace fossils being closely associated with the storm event layers, and stratigraphic successions with orbital cyclostratigraphic architecture. It is suggested that lower atmospheric oxygen level during the Early Paleozoic, the Ordovician radiation, dramatic transgression and warmer temperatures would result in the periodic anoxia in the Early-Middle Ordovician transition. This episode began at the later Early Ordovician and lasted about 3.4 Ma on the basis of orbital cyclostratigraphy.  相似文献   

中国台湾大鬼湖沉积物所保留之降尘记录   总被引：6，自引：0，他引：6       下载免费PDF全文

陈镇东  罗建育  万政康  蓝信企 《第四纪研究》2001,21(1):18-28

本文以中国台湾大鬼湖沉积物岩芯回推此区过去1600年以来PM10与空飘重金属之变化情形.湖区沉积物主要来自集水区冲刷来的岩屑及植物碎屑,一般为黑色,平均粒径30～50μm,PM10约10%～20%.但在干冷时期,由空飘来的祖国大陆北方沙尘较多,形成相对亮度指数较高的白层,其磁化率较高、平均粒径约10μm,且PM10可达60%;而从1350年以来,无机元素沉积累积速率较前期有所增加,且白层中大部分无机元素皆有较高的累积速率,可能导因于空飘物质输入量增加.较暖湿时期,则以亲有机质元素之沉积累积速率较高.  相似文献   

Coupling Locally Conservative Methods for Single Phase Flow     

Béatrice Rivière  Mary Wheeler 《Computational Geosciences》2002,6(3-4):269-284

This work presents the coupling of two locally conservative methods for elliptic problems: namely, the discontinuous Galerkin method and the mixed finite element method. The couplings can be defined with or without interface Lagrange multipliers. The formulations are shown to be equivalent. Optimal error estimates are given; penalty terms may or may not be included. In addition, the analysis for non-conforming grids is also discussed.  相似文献   

气候变化对华北地区冬小麦水分亏缺状况及生长的影响   总被引：9，自引：0，他引：9       下载免费PDF全文

王石立  娄秀荣 《应用气象学报》1996,7(3):308-315

根据多点多年气象资料、作物发育期资料和土壤水文资料，计算了未来气候变化情景下华北冬小麦主产区小麦不同发育阶段和全生育期内水分亏缺量的变化。结果表明，气温升高时小麦水分亏缺状况变差，亏缺量等值线南移，引起小麦气候适宜区范围缩小，减产额加大，产值降低，用于额外灌溉的生产费用增加。  相似文献   

Structural variation in Ca(TixSi1−x)O3 perovskites (1>x>0.65) and the ordered phase Ca2TiSiO6     

Kurt Leinenweber  Andrzej Grzechnik  Mary Voorhees  Alexandra Navrotsky  Nan Yao  Paul F. McMillan 《Physics and Chemistry of Minerals》1997,24(7):528-534

High pressure perovskites in the system CaTiO₃?CaSiO₃ in the composition range from 0 to 50% CaSiO₃ have been re-examined using powder x-ray diffraction, Raman spectroscopy, and transmission electron microscopy. In runs performed at 9 GPa and 1200 °C, a solid solution is obtained with compositions ranging from CaTiO₃ to near Ca(Ti_0.65Si_0.35)O₃, and with the orthorhombic distortion in the CaTiO₃ end-member diminishing to pseudocubic for Ca(Ti_0.65Si_0.35)O₃. Raman spectra show intensity changes and band broadening which are attributed to the reduction of orthorhombic character, but still indicate lower than cubic symmetry for the entire solid solution range. An ordered intermediate, Ca₂TiSiO₆, has been recovered from a run at 14 GPa at 1200 °C. The space group is Fm3m, with a=7.410(2)?Å, and the compound has the double perovskite structure. In this structure, Si-rich octahedral sites and Ti-rich octahedral sites alternate along the three principal axes. Transmission electron microscopy confirms the presence of the Fm3m ordered structure, and also documents the presence of lesser amounts of at least three other ordered perovskite structures which are not resolved in the x-ray data. These may account for extra features observed in the Raman spectrum which are inconsistent with mode assignments for the Fm3m phase. Non face-centered ordering schemes for these regions are suggested based on modeling of the HRTEM patterns.  相似文献   

刚性承台—桩群—土共同作用的两种迭代算法     

楼晓明  魏新江 《岩土力学》1997,18(3):72-74

针对现有承台-桩-土共同作用分析方法存在的问题，引进了两种迭代算法，通过理论和算例的比较分析，说明了这两种迭代算法用于承台-桩-土共同作用分析的特点和适用性。使用迭代法可避免满阵矩阵，大大节省计算内存，能在微机上实现对实际工程的共同作用分析。  相似文献