Wave-like aquatic propulsion of mono-hull marine vessels     

V.V. Krylov  E. Porteous 《Ocean Engineering》2010,37(4):378-386

The present paper describes results of the experimental investigation of a small-scale mono-hull model boat propelled by a localised flexural wave propagating along the plate of finite width forming the boat's keel. Forward propulsion of the boat was achieved through flexural wave propagation in the opposite direction, which is similar to the aquatic propulsion used in nature by stingrays. The model boat under consideration underwent a series of tests both in a Perspex water tank and in an experimental pool. In particular, the forward velocity of the boat has been measured for different frequencies and amplitudes of the flexural wave. The highest velocity achieved was 32 cm/s. The thrust and propulsive efficiency have been measured as well. The obtained value of the propulsive efficiency in the optimum regime was 51%. This indicates that the efficiency of this type of aquatic propulsion is comparable to that of dolphins and sharks (around 75%) and to that of a traditional propeller (around 70%). In contrast with a propeller though, the wave-like aquatic propulsion has the following advantages: it does not generate underwater noise and it is safe for people and marine animals.  相似文献   

水生动物对植物蛋白源利用的研究进展   总被引：17，自引：1，他引：17  

艾庆辉  谢小军 《中国海洋大学学报(自然科学版)》2005,35(6):929-935

综述了水生动物对植物蛋白源的利用.饲料中植物蛋白水平将显著影响鱼类的生长和生理生化状态.水生动物对植物蛋白源的利用与适口性、消化率和必需氨基酸平衡相关.同进实验动物的种类、食性和发育阶段均会对植物蛋白利用产生一定影响.水生动物饲料中植物蛋白源的适宜添加量主要受实验动物种类和饲料中蛋白质水平的影响.因此,通过添加限制性必需氨基酸和减少搞营养因子可以提高水生动物对植物蛋白源的利用.  相似文献   

A Classification of Hypersaline Waters, Based on Trophic Criteria   总被引：9，自引：0，他引：9  

F. D. Por 《Marine Ecology》1980,1(2):121-131

Abstract. A classification of hypersaline waters is proposed on the basis of the food chain structure of their biota. Four steps of increasing salinity and respective shortening of the food-chains are recognized, respectively named: alpha-, beta-, gamma- and delta-hypersaline waters.
Some general aspects, dealing with cosmopolitism of the biota, production, competition and benthic ecology in hypersaline waters are discussed.
The relevance of ecological studies in hypersaline waters to theoretical ecology and to the new technological uses of saline waters is briefly mentioned.  相似文献   

Terrestrial and Submerged Aquatic Vegetation Mapping in Fire Island National Seashore Using High Spatial Resolution Remote Sensing Data     

Yeqiao Wang  Michael Traber  Bryan Milstead  Sara Stevens 《Marine Geodesy》2007,30(1):77-95

The vegetation communities and spatial patterns on the Fire Island National Seashore are dynamic as the result of interactions with driving forces such as sand deposition, storm-driven over wash, salt spray, surface water, as well as with human disturbances. We used high spatial resolution QuickBird-2 satellite remote sensing data to map both terrestrial and submerged aquatic vegetation communities of the National Seashore. We adopted a stratified classification and unsupervised classification approach for mapping terrestrial vegetation types. Our classification scheme included detailed terrestrial vegetation types identified by previous vegetation mapping efforts of the National Park Service and three generalized categories of high-density seagrass, low-density seagrass coverages, and unvegetated bottom to map the submerged aquatic vegetation habitats. We used underwater videography, GPS-guided field reference photography, and bathymetric data to support remote sensing image classification and information extraction. This study achieved approximately 82% and 75% overall classification accuracy for the terrestrial and submnerged aquatic vegetations, respectively, and provided an updated vegetation inventory and change analysis for the Northeast Coastal and Barrier Network of the National Park Service.  相似文献   

面对水产饲料标准的思考     

陈人弼  陈涵贞 《台湾海峡》2001,20(Z1):148-150

水产饲料标准的颁布，规范了市场行为，但数量偏少，不利于对水产饲料质量的全面管理.我国实行推荐性饲料标准，有助于生产适销对路产品，但在卫生安全指标上仍应加以规范.  相似文献   

吡喹酮和克螨特复配驱虫制剂对一些水生饵料生物的毒性     

樊海平 《台湾海峡》2004,23(4):500-506

由吡喹酮和克螨特组成的复配制剂对小球藻、轮虫、蚤状溞、水蚯蚓和卤虫的毒性实验结果显示：复配制剂对轮虫的半致死浓度(LC50)为13．9mg／dm^3(24h)和3．03mg／dm^3(48h)．安全浓度(SC)为0．0432mg／dm^3；对蚤状溞的LC50为345．14mg／dm^3(24h)和17．5mg／dm^3(48h)，SC为0．0135mg／dm^3；对水蚯蚓的LC50为636．80mg／dm^3(24h)和79．07mg／dm^3(48h)，SC为0．366mg／dm^3；对卤虫无节幼虫的LC50为201．84mg／dm^3(24h)和8．91mg／dm^3(48h)．SC为0．00519mg／dm^3,复配制剂对水环境生物的破坏作用小．  相似文献   

鱼粉脂肪酸组成的分析研究   总被引：7，自引：1，他引：7  

宋永康  林虬  陈人弼 《台湾海峡》2004,23(1):88-93

本文应用气相色谱对水产饲料的主要原料——— 4类进口鱼粉的脂肪酸组成进行分析 ,结果表明 :①鱼粉中主要脂肪酸含量SFA为C1 6∶0、C1 8∶0 ,MUFA为C1 8∶1、C1 6∶1 ,PUFA为EPA和DHA .② 4类鱼粉中 ,美国、新西兰、俄罗斯的鱼粉MUFA含量较为接近 ,都在 4 0 %左右 ,但新西兰鱼粉的C1 8∶1含量较美国鱼粉高 ,其平均值分别为 2 50 %和 1 9.53% ,而C 2 0∶1、C2 2∶1 ,则比美国低一些 ,俄罗斯鱼粉的含量居两者之间 .智利鱼粉的MUFA比前 3种鱼粉低 ,只有 30 %左右 .③ 4类鱼粉中新西兰鱼粉的PUFA最低 ,它们的EPA与DHA的比值为 :美国鱼粉接近 1∶1 ,新西兰鱼粉为1∶1 .5～ 1∶3.2 ,俄罗斯鱼粉为 1∶1 .2～ 1∶1 .4 ,智利鱼粉为 1∶2左右 ,④智利鱼粉的C2 2∶5n 3明显高于其它 3类鱼粉 ,而C2 0∶1、和C2 2∶1则明显低于其它 3类鱼粉  相似文献   

Observations and model estimates of diurnal water temperature dynamics in mosquito breeding sites in western Kenya     

K. P. Paaijmans  A. F. G. Jacobs  W. Takken  B. G. Heusinkveld  A. K. Githeko  M. Dicke  A. A. M. Holtslag 《水文研究》2008,22(24):4789-4801

Water temperature is an important determinant of the growth and development of malaria mosquito immatures. To gain a better understanding of the daily temperature dynamics of malaria mosquito breeding sites and of the relationships between meteorological variables and water temperature, three clear water pools (diameter × depth: 0·16 × 0·04, 0·32 × 0·16 and 0·96 × 0·32 m) were created in Kenya. Continuous water temperature measurements at various depths were combined with weather data collections from a meteorological station. The water pools were homothermic, but the top water layer differed by up to about 2 °C in temperature, depending on weather conditions. Although the daily mean temperature of all water pools was similar (27·4–28·1 °C), the average recorded difference between the daily minimum and maximum temperature was 14·4 °C in the smallest versus 7·1 °C in the largest water pool. Average water temperature corresponded well with various meteorological variables. The temperature of each water pool was continuously higher than the air temperature. A model was developed that predicts the diurnal water temperature dynamics accurately, based on the estimated energy budget components of these water pools. The air–water interface appeared the most important boundary for energy exchange processes and on average 82–89% of the total energy was gained and lost at this boundary. Besides energy loss to longwave radiation, loss due to evaporation was high; the average estimated daily evaporation ranged from 4·2 mm in the smallest to 3·7 mm in the largest water pool. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

水生动物热休克蛋白研究进展   总被引：8，自引：2，他引：6  

董云伟  董双林  纪婷婷 《中国海洋大学学报(自然科学版)》2008,38(1):39-44

由于栖息环境的特殊性,水生动物热休克蛋白的诱导及其生态意义具有不同于陆生动物的特性.本文总结了近年来水生动物热休克蛋白方面的研究进展,介绍热休克蛋白的调节机制及其功能,归纳水生动物热休克蛋白对温度、环境污染和其他因子的反应,着重分析热休克蛋白表达在水生动物中热耐受性和交叉保护中的作用,及其对水生动物分布和适合度的影响.  相似文献   

Influence of environmental and prey variables on low tide shorebird habitat use within the Robbins Passage wetlands,Northwest Tasmania   总被引：1，自引：0，他引：1  

Fiona L. Spruzen  Alastair M.M. RichardsonEric J. Woehler 《Estuarine, Coastal and Shelf Science》2008

Shorebirds feed primarily on tidal flats, and their distribution over these flats is influenced by their prey and abiotic factors. These factors act by influencing the distribution and abundance of the prey, or the shorebirds ability to exploit it. The aims of this study were to investigate the low tide foraging distribution of shorebirds at four sites within the Robbins Passage wetlands, and the environmental and invertebrate factors that may influence their distribution. The greatest densities and number of shorebirds were found at Shipwreck Point and East Inlet. The shorebirds within-site distribution was also non-random, with the shorebirds present in greatest densities at the water's edge and low intertidal stratum, although this varied among species. Generally, on a small spatial scale, invertebrate diversity was positively correlated, and seagrass leaf mass was negatively correlated, with shorebird feeding density. On a large spatial scale, invertebrate biomass and seagrass root mass were positively correlated with shorebird feeding density. Invertebrate biomass and seagrass root mass explained 71% of the variance in total shorebird feeding density on the tidal flats. The variation in shorebird feeding density and diversity was therefore partly explained by invertebrate diversity and biomass, as well as the environmental factors seagrass roots and leaf mass and tidal flat area, although the strength of these relationships was influenced by the two different spatial scales of the study. The strength of the relationships between shorebird feeding density and the invertebrate and environmental variables was stronger on a large spatial scale. The presence of seagrass may have influenced shorebird-feeding density by affecting the invertebrate abundance and composition or the shorebirds ability to detect and capture their prey. The area of the tidal flat had opposing effects on the shorebird species. These results can be used to assist in the development of management plans for the Robbins Passage wetlands and the conservation of important shorebird areas.  相似文献