Biota of a subalpine springbrook in the Southern Alps     

B. Cowie  M. J. Winterbourn 《新西兰海洋与淡水研究杂志》2013,47(2):295-301

The flora and fauna of a subalpine springbrook at Cass in the Southern Alps of New Zealand was studied from April 1975 to January 1976. Spring water was moderately hard (30.0 g.m.^‐3), with high concentrations of dissolved oxygen (> 90% saturation) and carbon dioxide (5–14 g.m^‐3) and a temperature of 6.0–6.5°C. Three mosses covered much of the stream bed and formed distinct zones. Fissidens rigidulus inhabited torrential, water near the middle of the channel, Pterygophyllum quadrijarium. grew in the water‐saturated inner spray zone, and Cratoneuropsis relaxa inhabited the outer spray zone. In moss samples, 44 species of invertebrates were collected, mainly immature stages of insects. Zelandoperla jenestrata (Plecoptera), Zelolessica cheira (Trichoptera) a species of Empididae (Diptera) and several species of Chironomidae were most abundant in Fissidens; Austroperla cyrene (Plecoptera), a species of Helodidae (Coleoptera) and a triclad, Neppia montana, were most abundant in Pterygophyllum; an isopod, Styloniscus otakensis, was the only common animal on Cratoneuropsis. It is suggested that animal microdistribution patterns reflect differences in water saturation, flow rates, and detritus trapping ability within the moss zones.  相似文献   

Ocnus sacculus new species (Echinodermata: Holothuroidea), a brood‐protecting holothurian from southeastern New Zealand     

David L. Pawson 《新西兰海洋与淡水研究杂志》2013,47(3):227-230

A new species in the dendrochirotid holothurian genus Ocnus sensu lato is described from approximately 600 m depth in Taiaroa Canyon, off Otago, New Zealand. Ocnus sacculus new species has single rows of tubefeet only in the 3 ventral radii. Body‐wall ossicles consist of cups, knobbed 4‐holed buttons, and multi‐layered plates averaging 0.7 mm in diameter. Three brood pouches lie anteriorly on the inner surface of the body wall in 3 dorsal interradii; the mid‐dorsal pouch is largest. The pouches apparently have no permanent contact with the exterior; presumably birth takes place by rupture of the body wall.  相似文献   

Seasonal variation in the reproductive activity and biochemical composition of the Pacific oyster (Crassostrea gigas) from the Marlborough Sounds,New Zealand     

Jeffrey S. Ren  Islay D. Marsden  Alex H. Ross  David R. Schiel 《新西兰海洋与淡水研究杂志》2013,47(1):171-182

Reproductive cycles of the Pacific oyster Crassostrea gigas (Thunberg) from the Marlborough Sounds, New Zealand, were followed between June 1998 and January 2000. Histological examination of the gonad confirms an annual cycle with a winter inactive period followed by rapid gonad development and a single short spawning period. The population gonad index correlated with seawater temperature and changes in tissue dry weight, condition index, and biochemical components. In winter, few individuals with early gametogenic stages were present and rapid development of primary oocytes (diam. 11 μm) occurred during spring (September‐November). The developmental rate and the diameter of mature oocytes (37 μm) was similar for the 1998 and 1999 seasons. For a standard 110‐mm‐length oyster, maximal tissue body weight and condition index were recorded in December. Rapid weight loss in January was length dependent and was attributed to spawning. Temperature was the environmental variable which best correlated with the timing of gametogenesis. Food availability (phytoplankton biomass) may have been responsible for inter‐annual variations. The biochemical composition (% glycogen, lipid, protein) of separated gonad and somatic tissues were variable seasonally and annually. Gametogenesis (oocyte diameter) was associated with increased gonad protein and glycogen and a decrease in lipid concentrations. These changes are similar to those in Pacific oyster populations from other parts of the world.  相似文献   

Biogrouting of hydraulic fill fine sands for reclamation projects     

Jijian Lian  Hongyin Xu  Xiaoqing He  Dengfeng Fu  Shuwang Yan 《Marine Georesources & Geotechnology》2013,31(2):212-222

ABSTRACT

Biogrouting, which is a new method for soil improvement, was used in an attempt to cement a type of hydraulic fill fine sands (called black sands) in reclamation projects in Tianjin, China, to form a working layer for mechanical equipment. Several factors influencing biogrouting with regard to cementing solution, including injection frequency, reaction time, concentration, and flow rate, were controlled to prepare black sand columns. This paper reports on an investigation of bacterial fixation, calcium ion utilization, and calcium carbonate distributions of biogrouted sand specimens. At the end of the tests, the geotechnical performances of the sand specimens were determined. The results showed that the biogrouting method effectively solidified black sands, by increasing the unconfined compressive strength of a sand column to 1.91?MPa and reducing the permeability coefficient by three orders of magnitude. A relationship between the unconfined compressive strengths and calcium carbonate contents was put forward, in addition to a relationship between the permeability coefficients and the calcium carbonate contents. According to the experimental results, some reasonable suggestions regarding the application of biogrouting to the consolidation of hydraulic fill fine sands in reclamation projects were proposed.  相似文献   

Seismic performance of cylindrical latticed-intersected-three-dimensional-beam-system reticulated mega-structure with single-layer latticed-intersected-cylindrical-shell substructures     

《Soil Dynamics and Earthquake Engineering》2014

This paper is focused on the research of seismic performance of cylindrical latticed-intersected-three-dimensional-beam-system (LITDBS) reticulated mega-structure with single-layer latticed-intersected-cylindrical-shell (LICS) substructures by time history method accounting for geometrical nonlinearity. The distribution laws of the dynamic internal forces and those of the ratios of the dynamic to static internal forces of members in this innovative structure are first studied. The behaviors of the structure under different multi-component seismic actions are analyzed, and the reasonable components of the seismic action that should be considered in design are thus obtained. Then taking the maximum dynamic internal force of the structure as the index, a series of parametric analyses are carried out, and the suitable values of several key form parameters are recommended. Additionally, the results by the response spectrum method with those by the time history method are compared, which indicates that the former is not on the safe side. Therefore, the mode-superposition response spectrum method can only be used to do preliminary seismic design of this kind of structure, and the results must be checked by the time history method at the end.  相似文献   

纹藤壶和鳞笠藤壶雄性生殖系统的初步研究     

王艺磊  张子平  成华  李少菁 《热带海洋学报》1999,(4)

对厦门海区的纹藤壶　Balanusamphitriteamphitrite和鳞笠藤壶　Tetraclitasquamosasquamosa　雄性生殖系统进行解剖学、组织学和细胞化学的研究。结果表明:两种藤壶的雄性生殖系统均由精巢、输精管、贮精囊及交接器4部分组成。精巢内依次排列有精原细胞、精母细胞、精子细胞和成熟精子。输精管由一层上皮细胞围成,内可见成熟精子,贮精囊前端管壁结构与输精管相似,后端管壁厚,可分为4层结构。交接器结构复杂,内层为射精管,外层结构与贮精囊后段相似。精子为线形,头部附属小滴内有4—6个致密斑,鞭毛沿头部一侧着生。初步探讨了不同发育阶段的雄性生殖细胞碱性蛋白的变化及附属小滴的细胞化学特性及生理学特性  相似文献   

Population Dynamics and Reproductive Traits of Phytal Gastropods in Seagrass Bed in Otsuchi Bay, North-Eastern Japan   总被引：1，自引：0，他引：1  

Tetsuhiko Toyohara  Masahiro Nakaoka  & Keiko Aioi 《Marine Ecology》1999,20(3-4):273-289

  相似文献   

The oldest angiosperm—a tricarpous female reproductive fossil from western Liaoning Province, NE China   总被引：2，自引：0，他引：2  

Shuying Duan 《中国科学D辑(英文版)》1998,41(1):14-20

The fossil plant female reproductive organs each with a tricarpous were collected from the Yixian Formation, Chaoyang district, western Liaoning Province. The geological age of the Yixian Formation here is believed to be Late Jurassic, which places this fossil as the oldest angiosperm currently known. Its morphological characters are distinct from other known angiosperm reproductive organs as it has 3 ovaries, each with a terminal style and an apical stigma. 9 such organs compose a cyme. As this morphological arrangement is unique to this plant, a new genus and species has been established, namedChaoyangia liangii gen. et sp. nov. Project supported by the Special Finances of Biological Sciences and Technology, Chinese Academy of Sciences (the special item of the Ministry of Finance of the People’s Republic of China).  相似文献   

Investigation of the ingrowth of radioactive daughters of in Mediterranean sapropels as a potential dating tool     

Silke Severmann  John Thomson   《Chemical Geology》1998,150(3-4)

Five different sapropels (S1, S3–S6) from two sites (2750 m and 3308 m water depth) in the eastern Mediterranean were analysed for C_org content and specific activities of , , and . Anoxia in the sapropel sediments during or shortly after deposition leads to U enrichment, and the observed excess of over activity is consistent with a seawater source for authigenic U. In certain cases, the U profile shape in and around the sappropels is interpreted to indicate that oxidation shortly after sapropel formation has caused a post-depositional downwards migration of both U isotopes. Systematic variability of the activity ratio across the sapropel units indicates that a different diagenetic process has also led to preferential relocation of produced in situ from the parent. The construction of quasi-isochrons in successively older sapropel units demonstrate that radioactive secular equilibrium is approached by a systematic ingrowth of over time from the marked initial disequilibrium between and the U isotopes. The effects of post-depositional diagenesis violate the isochron model boundary conditions, however, and lead to a deviation of the isochron ages from the expected stratigraphic ages. Following assessment of each data point, some improvements in the calculated ages were achieved in one case by exclusion from the calculations of those points most severely affected by open system behaviour.  相似文献   

Persistence of pre-metamorphic C and O isotopic signatures in marbles subject to Pan-African granulite-facies metamorphism and U–Th mineralization (Tranomaro, Southeast Madagascar)     

P. Boulvais  S. Fourcade  G. Gruau  B. Moine  M. Cuney 《Chemical Geology》1998,150(3-4):247-262

The status of fluid regimes during the Pan-African granulite-facies metamorphism in Southern Madagascar was examined by means of a mineralogical and stable isotope study of marble lithologies. In the granulitic Tranomaro area, which is made up of metasedimentary rocks (metapelitic, leptynitic (felsic) and calc–silicate metasediments) and intruded by syn-granulitic granitic bodies, syn-granulitic mineralization (Th–U) and metasomatic transformations (marbles→pyroxenites) demonstrate that fluid circulation has occurred. The Tranomaro marbles can be subdivided into two compositional groups, either Mg-poor or Mg-rich. This division reflects pre-metamorphic compositional differences rather than different histories. On a regional scale, the marbles display a large variation in (from +19 to +6.5‰ relative to SMOW) but have a more restricted range (from +1.4 to −2.5‰ relative to PDB). The lowest values are observed in magnesian marbles, whereas calcic ones do not have values lower than +13.5‰. Both initially low and high marbles may have locally been infiltrated by the syn-metamorphic fluid flow which gave rise to pyroxenites and Th–U ores (thorianite). values of carbonate in Mg-rich marbles evolve from +7 up to 8.5‰ towards the contact with a metasomatic pyroxenite in a meter-scale profile across an infiltration zone. The mineralogy, as well as the large and small-scale isotopic results argue for: (i) a pre-metamorphic origin for the isotopic variations, probably related to pre-granulitic dolomitization, (ii) a lack of pervasive fluid infiltration capable of erasing pre-metamorphic isotopic compositional differences, (iii) an absence of mantle-derived C-bearing fluids in the infiltrated zones. For the area as a whole, the present data are consistent with the decarbonation of impure siliceous limestones and dolostones coupled with fluid release from syn-metamorphic granitic intrusions.  相似文献