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   

中华鲟产卵栖息地的三维水力因子适宜性分析          下载免费PDF全文

班璇  高欣  Panayiotis DIPLAS  肖飞  石小涛 《水科学进展》2018,29(1):80-88

建立三维水动力学模型分析中华鲟产卵栖息地水力因子的时空分布和中华鲟产卵时的适宜水力特性,为设计最佳的生态调度方案提供科技支撑。研究结果表明,中华鲟产卵栖息地的上产卵区水深和流速的变化主要受流量影响,涡量的变化主要受地形影响;中华鲟产卵前需要高流量脉冲刺激产卵。坝下与隔流堤之间流速和涡量值的大小与波动远大于其他区域,均值为2.4 m/s和11 m2/s。产卵栖息地水体表层、中层和底层的流速和水平涡量分布格局相似,均是在上产卵区值较大,空间分布多样性高。水体中层垂向涡量的值远大于底层和表层。产卵栖息地水体表层、中层和底层水力分布特征为中华鲟繁殖提供了有利的水力条件,体现出中华鲟对产卵栖息地不同功能区的自主选择性。  相似文献   

In search of thresholds for recruitment overfishing   总被引：2，自引：0，他引：2  

Myers  R. A.; Rosenberg  A. A.; Mace  P. M.; Barrowman  N.; Restrepo  V. R. 《ICES Journal of Marine Science》1994,51(2):191-205

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The location and timing of cod spawning around the British Isles   总被引：3，自引：3，他引：3  

Brander  K. M. 《ICES Journal of Marine Science》1994,51(1):71-89

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Did population collapse influence individual fecundity of Northwest Atlantic cod?     

Stares  J. C.; Rideout  R. M.; Morgan  M. J.; Brattey  J. 《ICES Journal of Marine Science》2007,64(7):1338-1347

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Seasonal differences in catches of leptocephali in the East China Sea and Suruga Bay, Japan   总被引：2，自引：0，他引：2  

Gen Minagawa  Michael J. Miller  Yobuo Kimura  Shun Watanabe  Akira Shinoda  Jun Aoyama  Katsumi Tsukamoto 《Estuarine, Coastal and Shelf Science》2007,71(3-4):730-740

The species composition, distribution, and size of eel larvae, or leptocephali, caught near the continental shelf in subtropical and temperate regions of East Asia were compared between two seasons (May–Jun and Oct–Dec) to learn about the seasonality of reproduction of marine eels. There was greater species richness and evidence of spawning by more species of marine eels during the late autumn surveys in both the East China Sea (ECS) and in Suruga Bay along the east coast of Japan. Small leptocephali <10 mm TL and a wide range of sizes of various taxa were collected during both seasons along the outer edge of the continental shelf in the ECS, indicating that some marine eels may spawn there all year. The lack of small leptocephali during the spring survey in Suruga Bay suggested that most eels have a clear seasonal cycle of summer or autumn spawning at the higher latitudes of coastal Japan where there is much greater fluctuation of water temperature throughout the year than in the ECS. At lower latitudes such as in the ECS, and in tropical areas where water temperatures are higher and more constant, some marine eels may spawn all year round.  相似文献   

Occurrence and Distribution of the Eggs and Larvae of Anchovy, <Emphasis Type="Italic">Engraulis japonicus</Emphasis>, in Jeju Strait,Korea, with Descriptions of Environmental Characteristics     

Seung-Jong?LeeEmail author  You-Bong?Go 《Journal of Oceanography》2005,61(3):603-611

The occurrence and distribution of eggs and larvae of anchovy, Engraulis japonicus, in Jeju Strait, Korea from May to November 2002 were investigated, and the relationships between the abundances of anchovy eggs and larvae and the oceanographic conditions, including meteorological data, were analyzed. During the sampling periods, the anchovy eggs occurred from May to October and about 95% of total egg abundance occurred in only two months from July to August, suggesting that the main spawning season of anchovies is confirmed in summer from July and August in Jeju Strait. The spawning area of anchovies gradually moved to the southern part of the survey area with time. The predominant anchovy larvae collected in this study were mostly smaller than 16.0 mm TL. Correlation analysis and multiple regression analysis showed that the anchovy egg abundance in the study area depended strongly on the wind conditions, especially less than 10 m/s, and increasing water temperature. Salinity variations also had significant effects on the abundance of anchovy larvae.  相似文献