Movement patterns and trajectories of ovigerous blue crabs Callinectes sapidus during the spawning migration     

Sarah D. Carr  Richard A. Tankersley  James L. Hench  Richard B. Forward  Jr.  Richard A. Luettich  Jr. 《Estuarine, Coastal and Shelf Science》2004,60(4):567-579

Female blue crabs (Callinectes sapidus Rathbun) migrate from low salinity estuarine regions to high salinity regions near the ocean to release larvae. During this migration, ovigerous females use ebb-tide transport, a vertical migratory behavior in which they ascend into the water column during ebb tides, to move seaward to larval release areas. In order to determine the relationship of ebb-tide vertical migrations to local currents and the influence of these vertical migrations on the horizontal transport of blue crabs in the estuary, ovigerous females with mature embryos (1–3 days from hatching) were tracked near Beaufort Inlet, North Carolina (USA), in July and August 2001 and 2002. Crabs were tagged and tracked using ultrasonic telemetry, and currents near the crabs were measured simultaneously with a shipboard acoustic Doppler current profiler.During the two seasons, eight crabs were successfully tracked for periods ranging from 3.9–37.0 h and for distances ranging from 1.9–10.6 km. All crabs migrated seaward during the tracking periods. Crabs moved episodically during all tidal phases with periods of movement on the order of minutes to an hour. They moved with local currents in terms of both speed and direction during ebb tides, consistent with ebb-tide transport, and moved down-estuary (seaward) in opposition to local currents during flood tides. The percentage of time that crabs were active was higher during night ebb tides than during day ebb tides or flood tides and increased with increasing ebb-tide current speed. Mean migratory speeds were 0.11, 0.04, 0.08 and 0.02 m s⁻¹ during night ebb, night flood, day ebb and day flood tides, respectively, and net migratory speeds were on the order of 5 km day⁻¹. Due to the episodic nature of the crabs' movements, the total distances that crabs traveled during ebb tides ranged from 10–40% of the distances that passive particles could have traveled under the same conditions.  相似文献   

Blue stragglers as stellar collision products: the angular momentum question     

Alison Sills  Tim Adams  Melvyn B. Davies 《Monthly notices of the Royal Astronomical Society》2005,358(3):716-725

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Evidence for population structuring of blue whiting (Micromesistius poutassou) in the Northeast Atlantic     

Was  Anna; Gosling  Elizabeth; McCrann  Karen; Mork  Jarle 《ICES Journal of Marine Science》2008,65(2):216-225

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A comparison of hydrodynamic techniques for modelling collisions between main-sequence stars     

Hy Trac  Alison Sills  Ue-Li Pen 《Monthly notices of the Royal Astronomical Society》2007,377(3):997-1005

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Climate impacts on global irrigation requirements under 19 GCMs,simulated with a vegetation and hydrology model     

Markus Konzmann  Jens Heinke 《水文科学杂志》2013,58(1):88-105

Abstract

This study quantifies global changes in irrigation requirements for areas presently equipped for irrigation of major crop types, using climate projections from 19 GCMs up to the 2080s. Analysis is based on results from the global eco-hydrological model LPJmL that simulates the complex and dynamic interplay of direct and indirect climate change effects upon irrigation requirements. We find a decrease in global irrigation demand by ～17% in the ensemble median, due to a combination of beneficial CO₂ effects on plants, shorter growing periods and regional precipitation increases. In contrast, increases of >20% are projected with a high likelihood (i.e. in more than two thirds of the climate change scenarios) for some regions, including southern Europe, and, with a lower likelihood, for parts of Asia and North America as well. If CO₂ effects were not accounted for, however, global irrigation demand would hardly change, and increases would prevail in most regions except for southern Asia (where higher precipitation is projected). We stress that the CO₂ effects may not be realized everywhere, that irrigation requirements will probably increase further due to growing global food demand (not considered here), and that a significant amount of water to meet future irrigation requirements will have to be taken from fossil groundwater, environmental flow reserves or diverted rivers.

Editor D. Koutsoyiannis; Associate editor A. Montanari

Citation Konzmann, M., Gerten, D., and Heinke, J., 2013. Climate impacts on global irrigation requirements under 19 GCMs, simulated with a vegetation and hydrology model. Hydrological Sciences Journal, 58 (1), 1–18.  相似文献   

山东半岛蓝色经济区地热资源与开发利用区划     

王秀芹  张平平  杨亚宾 《山东国土资源》2015,31(7)

为了适应山东半岛蓝色经济区多产业快速发展的需求,通过区内地热资源开发利用现状调查、抽水试验、地热地质钻探等资料及以往地热地质研究成果,对山东半岛蓝色经济区地热地质条件进行了分析总结,将其分为层状、带状热储类型进行了地热资源量计算,从地热资源勘察、开发、利用条件和地热资源开发前景方面入手,结合区内交通、经济发展等社会环境,对半岛蓝色经济区地热资源进行开发利用区划,提出了地热资源开发利用方案及保护措施。  相似文献   

Effects of different light conditions on repair of UV-B-induced damage in carpospores of Chondrus ocellatus Holm     

鞠青  肖慧  王悠  唐学玺 《中国海洋湖沼学报》2015,33(3):664-678

We evaluated the effects of ultraviolet-B(UV-B) radiation and different light conditions on the repair of UV-B-induced damage in carpospores of C hondrus ocellatus Holm(Rhodophyta) in laboratory experiments. Carpospores were treated daily with different doses of UV-B radiation for 48 days,when vertical branches had formed in all treatments; after each daily treatment,the carpospores were subjected to photosynthetically active radiation(PAR),darkness,red light,or blue light during a 2-h repair stage. Carpospore diameters were measured every 4 days. We measured the growth and cellular contents of cyclobutane pyrimidine dimers(CPDs),chlorophyll a,phycoerythrin,and UV-B-absorbing mycosporine-like amino acids(MAAs) in carpospores on Day 48. Low doses of UV-B radiation(36 and 72 J/m 2) accelerated the growth of C. ocellatus. However,as the amount of UV-B radiation increased,the growth rate decreased and morphological changes occurred. UV-B radiation significant damaged DNA and photosynthetic pigments and induced three kind of MAAs,palythine,asterina-330,and shinorine. PAR conditions were best for repairing UV-B-induced damage. Darkness promoted the activity of the DNA darkrepair mechanism. Red light enhanced phycoerythrin synthesis but inhibited light repair of DNA. Although blue light,increased the activity of DNA photolyase,greatly improving remediation efficiency,the growth and development of C. ocellatus carpospores were slower than in other light treatments.  相似文献   

Possible solution to the problem of the extreme mass ratio W UMa-type binaries     

B. Arbutina 《Monthly notices of the Royal Astronomical Society》2009,394(1):501-509

When the total angular momentum of a binary system is at a critical (minimum) value, a tidal instability occurs (Darwin's instability), eventually forcing the stars to merge into a single, rapidly rotating object. The instability sets in at some critical separation which in the case of contact binaries corresponds to a minimum mass ratio depending on dimensionless gyration radius k ₁. If one considers   n = 3  polytrope (fully radiative primary with  Γ₁= 4/3  ),   k ²₁= 0.075  and   q _min≈ 0.085–0.095  . There appears to be, however, some W UMa-type binaries with q values very close, if not below these theoretical limits, implying that primary in these systems is probably more centrally condensed. We try to solve the discrepancy between theory and observations by considering rotating polytropes. We show by deriving and solving a modified Lane–Emden equation for   n = 3  polytrope that including the effects of rotation does increase the central concentration and could reduce   q _min  to as low as 0.070–0.074, more consistent with the observed population.  相似文献   

Physical parameters of the continuum radiating layer of the star L2 Pup     

E. V. Ruban  A. A. Arkharov  E. I. Hagen-Thorn  V. V. Novikov 《Astrophysics》2009,52(1):88-102

Data from spectrophotometric observations in the 485-1105 nm range at different times are used to determine the basic physical parameters of the continuum radiating layer of L₂ Pup: spectrophotometric temperatures, radii, and velocities of recession from the star's center. The phase dependences of these parameters over a cycle, during which the temperature varied from 2300 to 2900 K and the variations in radius were as high as 60%, are determined. The radius of the radiating layer is seen to vary irregularly, the radius of the layer is found to depend on wavelength, and the variations in the expansion velocity are evaluated. Translated from Astrofizika, Vol. 52, No. 1, pp. 99–115 (February 2009).  相似文献   

亚硝基-R盐分光光度法测定铜镍锰矿中的钴     

孟亚东  孙洛新  尚保忠  傅小强 《岩矿测试》2010,29(2):190-192

利用钴与亚硝基R盐在pH 5.5~7的乙酸溶液中,生成红色可溶性络合物,进行光度测定。拟定了刚果(金)高铜、高镍、高锰样品中钴的测定方法。实验确定了样品的溶解方式、显色剂的浓度及用量、煮沸时间和放置时间,并对矿样中铁、铜、镍、锰等主要干扰元素进行了试验。分析结果经标准样品验证、方法比对,均符合分析规范要求。  相似文献