Caught in the act: the 20 December 2001 gravity flow event in Monterey Canyon     

C. K. Paull  W. Ussler  H. G. Greene  R. Keaten  P. Mitts  J. Barry 《Geo-Marine Letters》2003,22(4):227-232

A sediment gravity flow descended through the axis of Monterey Canyon on 20 December 2001 at 13:35 Pacific standard time. The timing of this event is documented by a current-meter package which recorded an 11.9-dbar pressure increase in less than 10 min and was found 550 m down-canyon from its deployment site, buried completely within a >70-cm-thick gravity flow deposit. This event is believed to have started in less than 290 m of water because an instrument at this location was also lost at the same time. A 178-cm core collected after the event from the axis of the canyon at 1,297-m water depth contained fresh, greenish, chlorophyll-rich organic material at 32-cm sub-bottom depth, suggesting the event extended to this water depth. The only trigger identified for this mass movement event appears to be moderate sea and surf conditions. Thus, gravity flow events of this magnitude do not require an exceptional triggering event.  相似文献   

Molecular identification of bloom-forming species Phaeocystis globosa(Prymnesiophyta)and its dispersal based on rDNA ITS sequence analysis   总被引：3，自引：1，他引：3  

Chen Yueqin  Shao Peng  Wang Ning  Zhou Hui  Qu Lianghu  Linda K. Medlin 《海洋学报(英文版)》2003,22(2)

Abstract-The colony-forming Phaeocystis species are causative agents of dense bloom occurrences incoastal waters worldwide. It is difficult to separate them because of the different morphologies associatedwith their colonial stages. In this study we applied molecular approaches to analyze the genetic variationof Phaeocystis globosa and Phaeocystis pouchetii from several geogrtaphic regions, and to assist in tracingthe dispersal of bloom-forming Phaeocystis species in coastal waters of China. The Sequences of the inter-nal transcribed sacers (ITS1 and ITS2) of rDNA and the 5.8S ribosomal RNA gene of Phaeocystisstrains were determined. Sequence comparison shows that P.globosa was the most divergent toP. pouchetii, exhibiting sequence divergence higher than 0.08. However, lower genetic divergences ex-isted between strains of P.globosa. The sequence comparison of the Phaeocystis rDNA ITS clearlyshows that the species isolated from the southeast coast of China is identified as P. globosa rather thanP. cf. po  相似文献   

Using benthic macrofauna to assess environmental quality of four intertidal mudflats in Hong Kong and Shenzhen Coast   总被引：4，自引：0，他引：4  

Cai Lizhe  Nora F. Y. Tam  Teresa W. Y. Wong  Ma Li  Gao Yang  Yuk-Shan Wong 《海洋学报(英文版)》2003,22(2):309-319

Abstract-Intertidal zone is a significant wetland between land and ocean. It plays an important rolein maintaining local ecological balance. Both Mai Po and Futian intertidal mudflats are located in Shen-zhen Bay and are important "refueling" point along the East Asian/Australian flyway of migratory birds.The environmental quality of Mai Po and Futian mudflats have aroused great concern due to rapid eco-nomic developments in Hong Kong and Shenzhen in recent decades. Microinfauna of Mai Po and Futianmudflats was investigated in December 2000 and the faunal data were used to assess their environmentalquality. Two other mudflats, namely Ma Wan Typhoon Shelter (a more disturbed area) and Luk Kengintertidal mudflat (a place with relatively less human disturbance), were also sampled for macroinfaunaand used as reference mudflats. Shannon-Weaver species diversity index (I_(sd)), biotic coefficient (C_b)and macrofaunal pollution index (I_(mp)) of the macrofauna community on four intertidal mudflats wereused to  相似文献   

Second-Order Wave Diffraction Around 3-D Bodies by A Time-Domain Method   总被引：1，自引：1，他引：1  

BAI  Wei 《中国海洋工程》2001,(1):73-84

A time-domain method is applied to simulate nonlinear wave diffraction around a surface piercing 3-D arbitrary body. The method involves the application of Taylor series expansions and the use of perturbation procedure to establish the corresponding boundary value problems with respect to a time-independent fluid domain. A boundary element method based on B-spline expansion is used to calculate the wave field at each time step, and the free surface boundary condition is satisfied to the second order of wave steepness by a numerical integration in time. An artificial damping layer is adopted on the free surface for the removal of wave reflection from the outer boundary. As an illustration, the method is used to compute the second-order wave forces and run-up on a surface-piercing circular cylinder. The present method is found to be accurate, computationally efficient, and numerically stable.  相似文献   

Locomotor activity rhythm in the Japanese eel Anguilla japonica elvers     

DOU Shuozeng  TSUKAMOTO Katsumi 《海洋学报(英文版)》2007,26(5):76-89

Under artificial LD cycles(6,12,18 L),the elvers of Japanese eel,Anguilla japonica,showed a 24 h cycle of locomotor activity rhythm being most active at light transitions:the eels' activity rose to a primary peak after lights-off,followed by a quiescent period during which they buried into the shelters or lying motionlessly on sand for most of the time,and then reached a secondary peak before lights-on.Elvers could resynchronize their activity rhythm with a new photo cycle within 4 d.Moreover,their activity level at dark phase significantly increased as the light period was prolonged:higher activity levels during shorter dark period.However,the elvers did not display clearly the existence of a circadian rhythm under constant light or dark conditions.The timing of daily activity rhythm evidenced in the Japanese eels may occur through the action of the LD cycles with a weak participation of an endogenous circadian system.In all the LD cycles,over 99% of the activity occurred in the dark phase,indicating that the eels were always nocturnally active no matter what time of day it might be.Under 12 L conditions,the eels' activity level and the time outside sand were significantly elevated both at light and dark phases as temperature increased from 10~15 to 20~25 ℃.The activity rhythm pattern(i.e.,two peaks occurring around light transitions) did not apparently change among temperatures.However,in contrast with the primary activity peaks immediately after lights-off at 20 and 25 ℃,the timing of the primary peaks at 10 and 15 ℃ showed a latency of a few hours following lights-off,indicating the inhibiting effect of low temperature on the eels' activity.  相似文献   

泰利台风对台湾东北黑潮入侵东海陆架影响的研究     

何源首  胡珀  殷玉齐  侯一筠 《海洋与湖沼》2020,51(1):40-50

本文利用卫星高度计数据和分析数据,并结合同时期现场深水潜标的流速观测数据,研究了超强台风泰利过境前后台湾东北附近海域流场、位势密度场、位势涡度场以及黑潮入侵东海陆架强度的变化。分析结果表明,泰利台风通过改变台湾东北陆坡附近海域的流场、位势密度场,显著地削弱(增强)了西段(东段)陆坡附近的位势涡度梯度,从而使得西段(东段)陆坡黑潮入侵东海陆架的强度显著增强(减弱)。此外,本文还区分了台湾东北西部陆坡附近表层的跨陆坡“上凸型”位势涡度分布与次表层的跨陆坡“下凹型”位势涡度分布,并认为次表层的跨陆坡“下凹型”位势涡度分布也应作为台湾东北西部陆坡附近“位势涡度障碍”的重要组成部分。本文的研究结果揭示了大气中的台风过程对台湾东北黑潮入侵东海陆架产生显著影响的关键过程及机制,相关结论可为台湾东北黑潮入侵东海陆架变化规律的研究提供有价值的参考。  相似文献   

礁膜配子放散条件的研究   总被引：2，自引：0，他引：2  

陈昌生 《台湾海峡》1996,15(2):154-158

本文报道了礁膜配子的放散与温度、光照、比重的关系。结果表明，自然海区的礁膜在白天大量放散配子。配子放散的适宜温度为１９－２１℃；光照为２０００－５０００ｌｘ时能促进配子大量放散出来；配子放散的适宜比重为１．０５－１．０２５；这些研究结果将为礁膜人工育苗提供一些科学依据。  相似文献   

不同水温对文昌鱼性腺发育的影响   总被引：10，自引：1，他引：10  

林加涵  方永强 《台湾海峡》1996,15(2):170-173,T001

研究表明，不同水温对文昌鱼性腺发育分化和成熟有十分显著的影响。１４℃对文昌鱼性腺发育没有显著的作用，２０和２５℃十分有利于性腺发育和成熟，经４０ｄ培养，出现一些雌、雄文昌鱼产卵和释精以及加速性腺发育。本文还讨论了水温促进性腺发育可能的机制。  相似文献   

用新显色剂3-甲氧基-甲亚胺H光度测定海水中的硼     

潘教麦  王芳  徐钟隽 《海洋科学》1994,18(1):64-66

采用新试剂３－甲氧基－甲亚胺Ｈ测定海水中的硼，加入ＥＤＴＡ和酒石酸掩蔽各种干扰离子，不须分离可直接测定，方法简便、快速、准确。  相似文献   

Role of mangrove in mercury cycling and removal in the Jiulong Estuary   总被引：4，自引：0，他引：4  

Lin Peng  Chen Ronghua 《海洋学报(英文版)》1990,9(4):622-624

Baseline of mercury in mangrove swamp The mercury content in sediments in the Jiulong Estuary was determined in 1984 and 1985(Table 1). The highest content of mercury in sediments (300×10~(-9)) was found in Ditou, contrast-ing strongly with the low content of 36×10~(-9) in Port Dongzhai in the Hainan Island. Tab1e 1 showsthat the average content of mercury in sediments in the Jiulong Estuary is 140×10~(-9) and the averageof four areas is 72×10~(-9). This value means that these areas have not been heavily contaminated by  相似文献