1961～2007年青藏高原四季开始日期的变化趋势分析   总被引：3，自引：1，他引：2  

范思睿  范广洲  赖欣  朱丽华 《气候与环境研究》2013,18(1):71-79

利用中国气象局国家气象信息中心提供的青藏高原60个测站1961～2007年逐日气温度资料,分析了青藏高原近47年来四季开始日期的时空变化特征和年代际变化趋势.结果表明,青藏高原的四季开始日期变化主要表现为春季和夏季的提前趋势,秋季和冬季的推后趋势,其中春季、冬季的变化显著,夏季、秋季的变化相对春季、冬季变化较小,四季开始日期的这种变化在增温明显的1990年代和21世纪初最为明显,并且春季和冬季开始日期的年代变化较大,而夏季和秋季开始日期的年际变化较大.这种变化趋势在空间分布上有所差异,春季和冬季开始日期变化的空间分布相似,春季和冬季开始日期的变化在空间上有相当的同步性而且都属于“中间高两边低”的分布状态,夏季和秋季开始日期变化的空间分布相似.此外,春季丌始日期在1990年代之前整体相对平稳并没有表现出明显的提早趋势,从1990年代开始变得较明显;夏季开始日期的提早变化相对平稳但年际变化较大;秋季开始日期的推迟相对平稳但是年际变化较大,1990年代有较明显的推迟趋势;冬季在1990年代表现出推迟趋势但是并不明显,但是到21世纪初表现出强烈的推迟.  相似文献   

Halosaurus pectoralis McCulloch (Pisces: Halosauridae) in the New Zealand region (note)     

D. G. McKnight 《新西兰海洋与淡水研究杂志》2013,47(3):555-556

Halosaurus pectoralis McCulloch is recorded from off Gisborne, New Zealand, and from south‐east of Lord Howe Island, thus adding a second species of the order Heteromi to the New Zealand fauna.  相似文献   

Studies on twelve common bivalve larvae,with notes on bivalve spawning seasons in New Zealand     

John D. Booth 《新西兰海洋与淡水研究杂志》2013,47(3):231-265

Twelve common bivalve larvae occurring in the plankton from the Bay of Islands (35°15'S, 174°10'E), Wellington Harbour (41°16'S, 174°51'E), and off Raumati Beach (40°56'S, 174°58'E), New Zealand, during 1970–72 are described and, wherever possible, provisionally identified. The seasonal occurrences of these larvae in the plankton are also described. Information on the spawning cycles of some New Zealand adult bivalves is reviewed; although some species have a short (4 months or less) spawning season, for most it is much longer, possibly with ‘trickle’ spawning through several months of the year.  相似文献   

Reproductive biology of horse mackerel Trachurus capensis and Trachurus trecae in Namibia and Angola     

《African Journal of Marine Science》2013,35(2):141-150

Harvest control measures for Namibia and Angola are defined using reference points for spawning biomass, which requires knowledge of spawning potential and dynamics of fishery stocks. The reproductive biology of two species of horse mackerel, Trachurus capensis and Trachurus trecae, in these waters was investigated for spawning distribution in time and space. Samples were collected during two scientific cruises conducted in February and July/August 2007 off the coast of Namibia and Angola. A total of 396 fish ovaries was examined to determine the spawning dynamics of the two species. The ovaries were histologically analysed and their oocyte distributions mapped. The length (TL)–weight relationships of the two species differed significantly. The observed development of oocyte recruitment and absence of a hiatus in the oocyte distribution indicated that these species are indeterminate spawners. Analyses of the data from the NatMIRC database (2001–2004) indicated annual changes in gonadosomatic index (GSI) for T. capensis at different latitudes, but these changes were small. GSI also fluctuated between years and areas, but there were no clear spatial or temporal trends, with averages ≤4.0% at all stations. The GSI of both species was not indicative of the histologically determined development of gonad maturity. Oocyte maturation for T. capensis indicated that smaller and younger fish spawn first. Batch fecundity (F) for T. trecae was best described by F = 4 986 TL (cm) – 99 645 (r ² = 0.83). This study provided the first analyses of oocyte development in time and space for the two species in the region.  相似文献   

Development of a sound reflection system for profiling sediments in shelf and slope depths     

E. J. Barnes 《新西兰海洋与淡水研究杂志》2013,47(1):70-86

A sound reflection system for obtaining profiles of sedimentary structures in shelf and slope depths to 500 m has been developed, based on an Edgerton 1 kJ boomer as sound source. A logarithmic response receiver allows optimal recording of signals over a wide dynamic range. Penetrations of up to 500 m have been obtained from structures within both unconsolidated sediments and folded lower Tertiary structures. The equipment works reliably at speeds up to 9 knots.  相似文献   

Gametogenic development and spawning of the razor clam,Zenatia acinaces in northeastern New Zealand     

P. E. Gribben 《新西兰海洋与淡水研究杂志》2013,47(6):1287-1296

The potential exists for New Zealand to exploit already established markets for razor clams through development of fisheries or aquaculture industries for the New Zealand razor clam, Zenatia acinaces. However, fishery or aquaculture development for Z. acinaces requires an understanding of the reproductive cycle including the timing of gametogenic development and spawning. The reproductive cycle of Z. acinaces was studied over an 11‐month period from May 2000 to March 2001 at Kennedy Bay, Coromandel Peninsula, using qualitative standard histological analysis and quantitative measures of oocytes. Histological analysis indicated that Z. acinaces is dioecious and gametogenic development was synchronous between the sexes. Gametogenesis began in June with gametes maturing quickly and by August/September (late winter/ early spring) most razor clams were ripe. Spawning began as early as September (spring) although spawning mainly occurred during October. By December (summer), nearly all clams were completely spent. From January 2001 most clams could not be sexed as all residual gametes were resorbed. Razor clams remained in this stage during March 2001. Spawning began when the water temperature was around its lowest, c. 15°C. Monthly mean number of eggs/follicle was sensitive to changes in reproductive development, closely following patterns observed in the qualitative stagings. Patterns of monthly mean oocyte diameters did not adequately describe the spawning events observed in qualitative analyses. Sex ratios were equal over the size range (69–99 mm shell length) of clams that could be sexed. The data presented in this study provide valuable information on the timing of spawning events for Z. acinaces, necessary for developing sustainable management strategies and selecting broodstock for aquaculture.  相似文献   

Migratory behaviour of spawning rainbow trout (Oncorhynchus mykiss) in the Tongariro River,New Zealand,after habitat alteration     

Mark R. Venman  Michel Dedual 《新西兰海洋与淡水研究杂志》2013,47(4):951-961

The movements of 92 adult rainbow trout (Oncorhynchus mykiss) from Lake Taupo into the Tongariro River, New Zealand, were monitored using radio‐telemetry every 3 days during the main spawning period between May and November 2003. This study repeated one previously conducted in 1995. Differences in spawning site preference and resting locations between 1995 and 2003 probably reflect differences in the nature of the river as a result of major natural floods that occurred in 1998. Average migration times were slower than in 1995 and the correlation between flow and mean daily movement was less distinct owing to the dry and settled weather during July and August, although fish did respond to freshets when they occurred. Peak movement occurred between 1600 and 2000 h NZ Standard Time with no movement occurring between midnight and 0400. Fish adjusted their movement in response to changing photoperiod. Nineteen fish were observed above the mouths of natal tributary streams for several weeks in the main river stem before entering these tributaries.  相似文献   

Characterization of hydraulic suitability of Chinese sturgeon (Acipenser sinensis) spawning habitat in the Yangtze River   总被引：1，自引：0，他引：1  

Yuankun Wang  Ziqiang Xia  Dong Wang 《水文研究》2012,26(23):3489-3498

Hydrodynamic flow fields affect the ecological processes such as the water diversity and the distribution of organisms. Understanding the hydrodynamic and ecological processes is critical for the restoration and protection of especially fragile ecological habitats in river systems. This study uses turbulent flow to characterize the ecological behaviour of Chinese Sturgeon (Acipenser sinensis) in the Yangtze River. The Delft3D‐Flow model, which is first validated with field‐measured data, is used to simulate the flow field within spawning habitats of Chinese Sturgeon, downstream of Gezhouba Dam. The model‐simulated turbulent kinetic energy (TKE) and its distribution pattern are then used to characterize the hydraulic environment of the fish's spawning habitat. For the spawning habitat, downstream of Gezhouba Dam, the lower limit of TKE for the Chinese Sturgeon egg mass field is 0.025 m²/s², which occurs at a velocity less than 1.7 m/s. Chinese Sturgeon prefers habitats with TKE range of 0.010 ~ 0.015 m²/s² for resting. This suggests that discharge regimes provide the basis for ecological regulation of the Three Gorges Reservoir and the scientific reference for river management. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

蒙古野驴(Equus hemionus)昼间行为时间分配初探   总被引：1，自引：0，他引：1  

刘伟  杨维康  黄怡  徐文轩  林杰  夏参军  徐峰  David Blank 《干旱区地理》2012,35(4):607-614

于2007 年和2010 年采用焦点动物取样法研究了新疆卡拉麦里山有蹄类野生动物保护区蒙古野驴昼间行为时间分配和活动节律,共采集行为数据460 h,观察蒙古野驴2 760 头次,将蒙古野驴昼间行为分为采食、移动、警戒、休息和“其他”5 类。采用卡方检验分析不同季节各种行为时间分配,结果表明：季节因素对蒙古野驴行为时间分配存在极显著影响（χ2=79.06,df=12,P<0.01）。采用ANOVA分析同季节不同行为间差异,结果表明,春季：移动、警戒、“其他”两两间无显著差异（[WTBX]P＞0.05）,其余两两间差异显著（P＜0.05）;夏季：仅移动与“其他”间无显著差异（P＞0.05）;秋冬季：仅警戒与“其他”间无显著差异（P＞0.05）。对蒙古野驴昼间活动节律研究结果表明,蒙古野驴采食时间比例在春季各时段均较高（＞45%）,仅中午（14:00～15:00）有1个低谷（27.62%）,夏秋季则为晨昏采食模式,冬季采食峰值（87.85%）在中午时段（13:00～14:00）。休息和采食高峰在各季节交叉出现,呈现此消彼长的趋势。各季节移动主要发生在晨昏时段。蒙古野驴以特定的行为时间分配模式和活动节律适应环境条件季节性变化,如气候条件、食物资源、人为干扰、生理期、昼间长度、捕食风险等。  相似文献   

Topographic changes of a supply‐limited inland parabolic sand dune during the incipient phase of stabilization     

Chris H. Hugenholtz 《地球表面变化过程与地形》2010,35(14):1674-1681

Topographic surveys on an inland parabolic sand dune over a six‐year period provide insight into the effects of diminishing local sand supply on dune stabilization. During the interval (2003–2009) sparse vegetation cover (Psoralea lanceolata) increased despite drier than normal moisture conditions and steady wind power during the growing season. Whereas these climatic conditions are typically ascribed to sustaining or increasing dune activity, here they coincide with stabilization. Through the use of geographic information system (GIS) analysis of volumetric changes it is shown that the increase of P. lanceolata can be attributed to the reduction of local sand supply from two blowouts along the arms of the parabolic dune during the six‐year period. These results show that climate is not the only control on dune activity in vegetated inland dunefields. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献