Albatross predation of juvenile southern blue whiting (Micromesistius australis) on the Campbell Plateau     

Yves Cherel  Sue Waugh  Stuart Hanchet 《新西兰海洋与淡水研究杂志》2013,47(3):437-441

Dietary samples collected at Campbell Island in summer 1997 indicate that southern blue whiting (Micromesistius australis) formed the bulk of the food of black‐browed albatrosses (Diomedea melanophrys impavida) during the chick‐rearing period. Birds preyed upon a single size class of fish with a mode at 80–90 mm standard length; fish were 4–5 months old and belonged to the 0+ age group. Satellite tracking showed that, when performing trips of short duration, adult albatrosses foraged within the 1000 m depth contour in the subantarctic zone north of Campbell Island. The feeding ecology of albatrosses thus suggests that juvenile (0+) southern blue whiting are pelagic and occur in dense schools in the top 5 m of the water column over the Campbell Plateau during the summer months. The high reliance of birds on juvenile southern blue whiting during the chick‐rearing period has implications for the management of the southern blue whiting fishery and the conservation of black‐browed albatrosses and other marine predators occurring in the New Zealand subantarctic area.  相似文献   

Prey selection and dietary overlap of shortfinned (Anguilla australis) and longfinned (A. dieffenbachii) eels during summer in the Horokiwi Stream,New Zealand     

P.M. Sagar  E. Graynoth  G. J. Glova 《新西兰海洋与淡水研究杂志》2013,47(4):931-939

Benthic macroinvertebrates were collected and the diets of shortfinned eels (Anguilla australis) and longfinned eels (Anguilla dieffenbachii) inhabiting a small coastal New Zealand stream were examined to investigate intraspecific and interspecific trophic partitioning and prey selection. Our results showed intraspecific segregation of preferred prey among three size classes of juvenile shortfinned eels, but there was significant overlap between different size classes of longfinned eels. All size classes of both species of eel fed nocturnally on similar prey, and so there was no indication of temporal or trophic segregation. Therefore, habitat separation is assumed to be the main mechanism to reduce interspecific competition in these two co‐occurring species of eels.  相似文献   

Effects of sample size on numerical estimates of diel prey consumption in a fish population     

Brendan C. Ebner  Ryan R.J. McAllister  Phil Suter 《新西兰海洋与淡水研究杂志》2013,47(2):579-590

Numerical data based on stomach content analysis of the zooplanktivorous freshwater fish, Retropinna semoni, were used to examine the effect of fish sample size on mean counts of dominant prey items. Fifty adult R. semoni were collected from throughout the open‐water of Lake Benanee, Australia at each of five times over a diel period. Bootstrapping was used to generate confidence intervals around sample means, and markedly more accurate means were obtained from samples collected in the day than the night. High variation in night samples was the by‐product of a diurnal feeding regime. Traditional sample sizes of 10 to 15 stomachs resulted in reasonable confidence intervals of sample means derived from collections on the first day, corresponding to uniform feeding patterns in the population. However, increased sample sizes were required to describe more complex feeding behaviour on the second day, when a proportion of the population switched to an alternative prey source.  相似文献   

除草剂百草枯对褶皱臂尾轮虫(Brachionus plicatilis)摄食和实验种群动态的影响          下载免费PDF全文

谢志浩  屠燕萍  俞泓伶  郑琴 《海洋与湖沼》2013,44(2):299-304

采用实验生态学方法研究了除草剂百草枯对褶皱臂尾轮虫(Brachionus plicatilis)的摄食和种群动态的影响。结果表明,百草枯对褶皱臂尾轮虫的24hLC50为9.17mg/L,对褶皱臂尾轮虫的摄食具有明显的抑制作用。实验浓度下褶皱臂尾轮虫对小球藻的滤水率和摄食率随百草枯浓度的增加先下降后升高。百草枯对褶皱臂尾轮虫种群动态影响显著,使轮虫的胚胎发育时间、繁殖前期和繁殖后期延长,繁殖期和平均寿命缩短,产卵量和繁殖率降低。轮虫的净生殖率和世代时间均低于对照,不同百草枯浓度下轮虫能够维持一定的种群增长。  相似文献   

花鲈仔、稚、幼鱼摄食习性与生长的研究   总被引：39，自引：3，他引：36  

张雅芝  郑金宝  谢仰杰  郑斯电 《海洋学报》1999,21(5):110-119

分析了花鲈仔、稚、幼鱼的摄食习性与生长.结果表明,在水温为15.5～16.5℃时,花妒仔鱼孵出约140h左右开口摄食,开口饵料为小型臂尾轮虫.全长10mm左右的仔鱼可摄食卤虫幼体,全长11mm左右的个体可摄食枝角类.对431尾仔、稚、幼鱼观察结果,在实验条件下其摄食率高达99.1%,胃饱满系数波动于2.38%～16.48%之间,日摄食指数在45%～60%.其摄食强度具明显的昼夜节律,以16:00～20:00胃饱满度最高.仔、稚鱼夜间基本不摄食,部分幼鱼个体少量摄食.仔、稚、幼鱼个体间生长速度具有一定的差异性.其体重与摄食量的关系符合直线方程y=0.1018+8.3261×10-2x;全长与体重的相关关系可用ω=1.6473×10-3L3.4743表示,全长与日龄的关系式为L_t=5.5242e1.9681×10-2D;体重与日龄的回归方程为ω=0.5836e6.9208×10-2D.  相似文献   

海洋药物及海洋功能食品的研究现状和开发思路   总被引：4，自引：0，他引：4  

李东风 《海洋学研究》1999,17(2):69-74

简述国内外海洋药物及功能食品的研究和开发现状,结合我省的具体情况,提出相应的发展规划和科技投入思路  相似文献   

复合型前置库系统去除面源主要污染物的研究   总被引：1，自引：0，他引：1  

边博  吴海锁  徐志荣  王惠中  姜伟立 《湖泊科学》2013,25(3):352-358

以江苏省溧阳市塘马水库水源地水质安全保障工程为背景,针对水库型水源地面源污染存在的主要问题,构建以沉淀区、浅水区、深水区、潜流人工湿地及生物填料组成强化净化区的复合型前置库分区净化系统,研究面源主要污染物去除规律,为工程示范提供技术参数.结果表明,系统滞水时间为1 d时,去除氮、磷、COD_Cr均有良好效果,分别达到了67.2%、68.2%及89.3%,滞水时间为2~3 d时各污染物去除率增加较少并趋于稳定.引入潜流湿地及强化净化区明显提高了SS、氮、磷、有机物的去除效果,特别是提升了对小颗粒(粒径小于15μm)的去除效果,基于上述研究结果,建议工程示范中滞水时间为2~3 d,并适当优化系统分区结构,提高复合型前置库的净化效率及面积利用率.  相似文献   

台湾海峡及邻近海域6种对虾食性特征及其营养级研究   总被引：3，自引：0，他引：3  

黄美珍 《台湾海峡》2004,23(4):481-488

本文主要研究台湾海峡及邻近海域6种对虾的食性特征与营养级.研究结果表明,它们皆为混合食性型的甲壳动物.哈氏仿对虾、鹰爪虾和周氏新对虾的主要饵料生物属底栖生物和浮游动物生态类群,中华管鞭虾和须赤虾的主要饵料生物属浮游动物和底栖生物生态类群;它们的营养级范围在1.64～2.14之间.周氏新对虾、角突仿对虾、须赤虾和鹰爪虾属第二营养层次的杂食性动物,哈氏仿对虾和中华管鞭虾属第三营养层次的低级肉食性动物;它们的食物生境宽度范围为6.48～1.24,其大小范围依次为:哈氏仿对虾、中华管鞭虾、鹰爪虾、周氏新对虾、须赤虾、角突仿对虾;6种虾类之间的食物的重叠指数0.008～0.716.除了周氏新对虾与其它虾类之间食物的重叠指数<0.15外,其它5种虾类之间(食物的重叠指数0.387～0.716)都存在竞争饵料资源的问题.挠足类、长尾类、稚幼鱼、多毛类、硅藻类和肉足鞭毛虫是虾类共同争食的饵料生物.  相似文献   

Performance analysis of integrated GPS/GLONASS carrier phase-based positioning     

Dai Liwen  Han Shaowei  Chris Rizos 《地球空间信息科学学报》2013,16(4):9-18

Due to the different signal frequencies for the GLONASS satellites, the commonly-used double-differencing procedure for carrier phase data processing can not be implemented in its straightforward form, as in the case of GPS. In this paper a novel data processing strategy, involving a three-step procedure, for integrated GPS/GLONASS positioning is proposed. The first is pseudo-range-based positioning, that uses double-differenced (DD) GPS pseudo-range and single-differenced (SD) GLONASS pseudo-range measurements to derive the initial position and receiver clock bias. The second is forming DD measurements (expressed in cycles) in order to estimate the ambiguities, by using the receiver clock bias estimated in the above step. The third is to form DD measurements (expressed in metric units) with the unknown SD integer ambiguity for the GLONASS reference satellite as the only parameter (which is constant before a cycle slip occurs for this satellite). A real-time stochastic model estimated by residual series over previous epochs is proposed for integrated GPS/GLONASS carrier phase and pseudo-range data processing. Other associated issues, such as cycle slip detection, validation criteria and adaptive procedure(s) for ambiguity resolution, is also discussed. The performance of this data processing strategy will be demonstrated through case study examples of rapid static positioning and kinematic positioning. From four experiments carried out to date, the results indicate that rapid static positioning requires 1 minute of single frequency GPS/GLONASS data for 100% positioning success rate. The single epoch positioning solution for kinematic positioning can achieve 94.6% success rate over short baselines (<6 km).  相似文献   

Retail Enterprise on the U.S. Urban Periphery: The Role of Immigrant Ethnic Groups in the Late-19th Century     

《Urban geography》2013,34(7):682-701

This research adds to knowledge about ethnic entrepreneurship in U.S. cities by testing the hypothesis that, in the late-19th century, levels of retail enterprise of entrepreneurial ethnic groups (e.g., Russian and Polish Jews) were highest in the most remote locations of the nation's urban-regional hierarchy. This hypothesis is based on the proposition that (1) "gateway cities" in the hinterlands of a society are bustling centers of commerce that offer unusually good prospects for retail enterprise, and (2) ethnic groups that are richly endowed with entrepreneurial resources can most fully exploit the advantages of such locations. An analysis of census data, guided by the "interactionist approach" to the study of entrepreneurship, supports this hypothesis and advances the literature on the ethnic economy by suggesting that a city's position in an urban-regional hierarchy (i.e., core vs. peripheral location) is a key element of the opportunity structure for ethnic entrepreneurship in that city.  相似文献