Interannual and geographical variability of the brood size of the euphausiids Euphausia pacifica and Thysanoessa spinifera along the Oregon coast (1999–2004)     

Jaime Gmez-Gutirrez  Leah R. Feinberg  Tracy C. Shaw  William T. Peterson 《Deep Sea Research Part I: Oceanographic Research Papers》2007,54(12):2145-2169

Brood sizes of 1259 adult female Euphausia pacifica and Thysanoessa spinifera were measured during 48 h incubations (10 °C, ±0.5 °C) on 27 oceanographic cruises between July 1999 and September 2004. The data set includes measurements from several stations off Newport, Oregon (Newport Hydrographic line, 44°39′N) made over a 5-year period and measurements from 14 more extensive cruises at stations representative of continental shelf, slope, and oceanic waters off Oregon and California, USA. E. pacifica had similar brood sizes at inshore (<200 m) and offshore (>200 m) stations with an average of 151 and 139 eggs brood⁻¹ fem⁻¹, respectively. T. spinifera brood sizes were considerably higher at inshore stations—particularly at Heceta Bank (44°N) and south of Cape Blanco (42°50′N)—than at offshore stations, 155 and 107 eggs brood⁻¹ fem⁻¹, respectively. Average brood sizes of E. pacifica increased during the study period, from 125 (in 2000) to 171 eggs brood⁻¹ fem⁻¹ (in 2003). Average percentage of carbon weight invested in spawning (reproductive effort) was higher in E. pacifica (14%) than in T. spinifera (6%), because both species have similar brood size but T. spinifera females are larger than E. pacifica females and produce smaller eggs. Reproductive effort for both species was higher during summer 2002, probably associated with anomalous cool subarctic waters and high chl-a concentration observed during that summer. Brood sizes and chl-a values remained relatively high in 2003–2004 compared to the 1999–2001 period. Geographical and temporal variability in brood sizes for both species were significantly correlated with in situ measurements of chl-a concentration but not with sea surface temperature. No gravid females were collected during late autumn and winter cruises, thus the spawning season along the Oregon coast appears to extend from March through September for both species. However, T. spinifera usually starts reproductive activity earlier in the spring (March) than E. pacifica. Both species had their highest brood sizes in summer during the period of most intense upwelling, which is associated with an increase in regional phytoplankton standing stock.  相似文献   

Latitudinal comparison of spawning season and growth of 0-group sole, Solea solea (L.)     

C. Vinagre  R. Amara  A. Maia  H.N. Cabral 《Estuarine, Coastal and Shelf Science》2008

0-Group sole, Solea solea (Linnaeus, 1758) were sampled in four nursery grounds: two on the Northern French coast and two on the Portuguese coast. Juvenile sole were collected at the Vilaine estuary (Northern Bay of Biscay) in 1992, in the Authie estuary (Eastern English Channel) in 1997, and in the Douro and Tagus estuary (Northern and central Portugal, respectively) in 2005. Left lapilli otoliths were used to estimate age and investigate variability in growth rates and hatch dates. In the French study areas nursery colonisation ended in early June in the Vilaine estuary and in late June in the Authie estuary. In the Portuguese estuaries nursery colonisation ended in May in the Douro estuary and in late June in the Tagus estuary. Growth rates were higher in the Portuguese estuaries, 0.767 mm d⁻¹ in the Tagus estuary and 0.903 mm d⁻¹ in the Douro estuary. In the French nurseries, growth rates were estimated to be 0.473 mm d⁻¹ in the Villaine estuary and 0.460 mm d⁻¹ in the Authie estuary. Data on growth rates from other studies shows that growth rates are higher at lower latitudes, probably due to higher water temperature. Spawning took place between early January and early April in the Villaine estuary's coastal area in 1992. In 1997, in the Authie estuary spawning started in late January and ended in early April. On the Douro estuary's adjacent coast spawning started in mid-January and ended in late March, in 2005, while on the Tagus estuary's adjacent coast spawning started in mid-February and ended in mid-April, in the same year. Literature analysis of the spawning period of sole along a latitudinal gradient ranging from 38°N to 55°N in the Northeast Atlantic indicated that there is a latitudinal trend, in that spawning starts sooner at lower latitudes. Results support that local conditions, particularly hydrodynamics, may overrule general latitudinal trends.  相似文献   

南海北部陆架区海域蓝圆鲹产卵场的研究   总被引：1，自引：0，他引：1  

陈国宝  李永振  陈丕茂 《热带海洋学报》2003,22(6):22-28

根据1997年12月到1999年6月在南海北部陆架区进行1a的4个季度共9个航次的底拖网渔业资源调查的资料,采用统计分析的方法分析了南海北部陆架区蓝圆鲹Decapterus maruadsi性腺成熟度的组成及分布、季节变化和水深变化。结果表明,南海北部陆架区海域蓝的产卵场位于海南岛东部近岸海区和北部湾湾口海区;产卵期主要集中在春季,和历史资料相比产卵期有明显缩短;产卵水深增加,有外移的趋向。  相似文献   

大化水库地震分析     

光耀华 《大地测量与地球动力学》1992,(1)

大化水库自1982年蓄水后发生频繁的微弱地震,主要有6个小震群,延续时间长达7年,但由于震级很小(最大震级Ms1.7),对电站运行无影响。从地震发展趋势分析,目前已处于衰减过程中,但微震仍可能继续一段时间,故地震监测工作应继续进行。  相似文献   

Marine Geomorphology in the Design of Marine Reserve Networks     

William D. Heyman  Dawn J. Wright 《The Professional geographer》2013,65(4):429-442

Marine environments, key life-support systems for the earth, are under severe threat. Issues associated with managing these common property resources are complex and interrelated. Networks of marine reserves can be valuable for mitigating threats to marine systems, yet the successful design and implementation of such networks has been limited. Efficient ways to conserve marine environments are urgently needed. This Focus Section of The Professional Geographer explores the development of marine reserve networks based on geomorphology, fish biology, ecological connectivity, and appropriate governance. The articles in this Focus Section offer examples of the following: (1) distinctive reef geomorphology dictating the spawning locations of reef fishes, which in turn serve as critical source sites for the replenishment of distant reefs by means of larval transport; (2) an example of a simplified oceanographic model that predicts larval transport from fish breeding sites to important nursery areas; and (3) a case study of the development of a marine reserve network that illustrates key elements of a successful strategy. In sum, this Focus Section offers case studies that show the value of marine geomorphology, oceanographic connectivity, and stakeholder involvement as key elements of multidisciplinary geographic studies applied to the design of marine reserve networks. Geographers can further contribute to the conservation and management of coastal and marine ecosystems in many ways that involve subdisciplines of remote sensing and geographic information systems, political and economic geography, political ecology, and ethnography.  相似文献   

Tools for gauging the capacity of salmon spawning substrates          下载免费PDF全文

Brandon T. Overstreet  Clifford S. Riebe  John K. Wooster  Leonard S. Sklar  Dino Bellugi 《地球表面变化过程与地形》2016,41(1):130-142

We present a set of river management tools based on a recently developed method for estimating the amount of salmon spawning habitat in coarse‐bedded rivers. The method, which was developed from a mechanistic model of redd building by female salmon, combines empirical relationships between fish length, redd area, and the sizes of particles moved by fish during spawning. Model inputs are the grain‐size indices D₅₀ and D₈₄ and an estimate of female fish length, which is used to predict the size of the redd that they will build and the size of the largest particle that they can move on the bed. Outputs include predictions of the fraction of the bed that the fish can use for redd building and the number of redds that they can build within the useable area. We cast the model into easy‐to‐use look‐up tables, charts, an Excel worksheet, a JavaScript web applet, and a MATLAB user interface. We explain how these tools can be used in a new, mechanistic approach to assessing spawning substrates and optimizing gravel augmentation projects in coarse‐bedded rivers. © 2016 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd.  相似文献   

Sperm swimming in the polychaete Galeolaria caespitosa shows substantial inter-individual variability in response to future ocean acidification     

《Marine pollution bulletin》2014,78(1-2):213-217

The rapidity of ocean acidification intensifies selection pressure for resilient phenotypes, particularly during sensitive early life stages. The scope for selection is greater in species with greater within-species variation in responses to changing environments, thus enhancing the potential for adaptation. We investigated among-male variation in sperm swimming responses (percent motility and swimming speeds) of the serpulid polychaete Galeolaria caespitosa to near- (ΔpH −0.3) and far-future ocean acidification (ΔpH −0.5). Responses of sperm swimming to acidification varied significantly among males and were overall negative. Robust sperm swimming behavior under near-future ocean acidification in some males may ameliorate climate change impacts, if traits associated with robustness are heritable, and thereby enhance the potential for adaptation to far-future conditions. Reduced sperm swimming in the majority of male G. caespitosa may decrease their fertilization success in a high CO₂ future ocean. Resultant changes in offspring production could affect recruitment success and population fitness downstream.  相似文献   

低氧对中华哲水蚤存活和繁殖影响的实验研究     

王巧宁  颜天  周名江 《海洋科学》2013,37(2):12-16

为研究低氧对海洋浮游生物关键种存活、繁殖等的影响,作者采用了实验室模拟低氧环境的方法,研究了低溶解氧(dissolved oxygen, DO)浓度对中华哲水蚤(Calanus sinicus)致死率、产卵和孵化的影响.研究发现,中华哲水蚤对低氧环境比较敏感,当DO质量浓度为2 mg/L左右时,中华哲水蚤会在1 h内全部死亡;当DO质量浓度为3 mg/L左右时,中华哲水蚤会在96 h内全部死亡;当DO质量浓度为4~6 mg/L 时,基本无死亡,但对中华哲水蚤的产卵有明显抑制作用,首次产卵时间推迟,产卵周期缩短.当DO质量浓度为4 mg/L时,基本不产卵,当DO质量浓度为6 mg/L时,产卵量也仅为常氧组的15%左右.当DO质量浓度为4~6 mg/L时,中华哲水蚤所产卵的孵化率为常氧组的60%左右,但差异不显著.可见,低氧对中华哲水蚤的存活和繁殖均有抑制作用,长时间低氧很可能会降低中华哲水蚤的种群数量,甚至改变海洋生态系统结构.  相似文献   

Cyclonic eddies reveal Oegopsida squid egg balloon masses in the Agulhas Current,South Africa     

《African Journal of Marine Science》2013,35(2):239-246

In 2005, 2006, 2007 and 2011, distinct Oegopsida squid egg masses were observed by scuba divers on the narrow southern KwaZulu-Natal (KZN) shelf in depths of 35–50 m off the coastal resorts of Park Rynie, Pumula and Port Edward, South Africa. In 2006, larvae in the egg balloons were sampled. DNA barcoding (i.e. cytochrome c oxidase subunit 1 sequencing) linked the larvae to the genus Lycoteuthis, a group commonly found on the continental slope of the Agulhas Bank and the west coast of South Africa. In all cases, the sightings were concomitant with low water temperatures of 14–18 °C, indicative of shelf edge upwelling. Historical ship-collected CTD data show these cooler waters to originate from a depth of 100–180 m on the KZN continental slope. Complementary satellite imagery revealed the cooler water and discoveries of the egg balloons to be coincident with cold core cyclonic eddies embedded in the shoreward boundary of the Agulhas Current. The temperature data suggest that these egg balloons, in the absence of cyclonic eddy activity, would normally be found in the current on a density surface at a depth of ～130 m where velocities are typically around 100 cm s^–1.  相似文献   

华北地区地下流体中期和转折型短期异常成因分析   总被引：1，自引：0，他引：1       下载免费PDF全文

平建军  王吉易  张子广  陈建国  黄万发 《地震地质》2004,26(2):355-363

结合观测井孔的水文地质条件、大气降水资料 ,深入剖析了华北地区水位、水氡的中期和转折型短期异常变化的直接原因 ,认为水位异常是由于降水量的增大与减少造成的 ,其形成机制主要为降水渗入补给 ;水氡异常的形成原因主要为降水渗入 -混合机制。进而提出“深浅构造的互动作用” ,用以解释流体异常与地震的关系 ,其论点是 :降水、地下水变化可诱发 (活化 )浅层的构造变动 ,而浅层构造活动又引发深部构造活动和地震的发生 ;反之 ,深部构造的活动和地震的孕育 ,使浅层岩石的应力增强 ,在降水、地下水的诱发作用下 ,可导致浅层的构造活动。降水引起的地下水异常是一种广义的地震前兆  相似文献