Effects of different dietary lipid sources on growth performance and tissue fatty acid composition of juvenile swimming crab Portunus trituberculatus

This study was conducted to evaluate the effects of dietary lipid sources on the growth performance and fatty acid composition of the swimming crab, P ortunus trituberculatus. Four isonitrogenous and isoenergetic experimental diets were formulated to contain four separate lipid sources, including fish, soybean, rapeseed, and linseed oils(FO, SO, RO, and LO, respectively). With three replicates of 18 crabs each for each diet, crabs(initial body weight, 17.00 ±0.09 g) were fed twice daily for 8 weeks. There were no significant differences among these groups in terms of weight gain, specific growth rate, and hepatosomatic index. However, the RO groups' survival rate was significantly lower than FO groups. The feed conversion and protein efficiency ratios of RO groups were poorer than other groups. The proximate compositions of whole body and hepatopancreas were significantly affected by these dietary treatments. Tissue fatty acid composition mainly reflected dietary fatty acid compositions. Crabs fed FO diets exhibited significantly higher arachidonic, eicosapentaenoic, and docosahexaenoic acid contents in muscle and hepatopancreas compared with VO crabs. Linoleic, oleic, and linolenic acids in muscle and hepatopancreas were the highest in the SO, RO, and LO groups, respectively. The present study suggested that SO and LO could substitute for FO in fishmeal-based diets for swimming crabs, without affecting growth performance and survival.

Evaluation approaches of fish swimming performance

Swimming speeds are the most important index for the evaluation of the fish swimming performance. The terminologies and classifications of the fish swimming performance were summarized in this paper. Taking into consideration of the widely used evaluation approaches of the fish swimming performance by different researchers, a recommended classification methodology of the fish swimming performance was proposed by the authors. And a new concept of the swimming speed, the Maximum Domed Swimming Speed (DSS), was introduced into this new classification framework together with a discussion on its calculation method and the practical significance. According to the classification system, the fish swimming speeds are classified into five categories: Optimum Swimming Speed, Maximum Sustained Swimming Speed, Critical Swimming Speed, Maximum Domed Swimming Speed, and Burst Swimming Speed. Other concepts of swimming speeds are generally merged into the above five categories, respectively. Furthermore, possible relevancies among the Maximum Sustained Swimming Speed (MSS), the Critical Swimming Speed (CSS), and the Maximum Domed Swimming Speed (DSS) were discussed. It was concluded that these three swimming speeds, in a sense, can be regarded as the equivalent indices for the evaluation of fish swimming performance.

Ecotoxicological effects of waterborne PFOS exposure on swimming performance and energy expenditure in juvenile goldfish (Carassius auratus)

The potential risks of perfluorooctane sulfonate （PFOS） are of increasing ecological concern. Swimming performance is linked to the fitness and health of fish. However, the impacts of PFOS on swimming performance remain largely unknown. We investigated the ecotoxicological effects of acute exposure to PFOS on the swimming performance and energy expenditure of juvenile goldfish （Carassius auratus）. The fish were exposed to a range of PFOS concentrations （0, 0.5, 2, 8 and 32 mg/L） for 48 hr. The spontaneous swimming activity, fast-start swimming performance, critical swimming speed （Ucrit） and active metabolic rate （AMR） of the goldfish were examined after exposure to PFOS. PFOS exposure resulted in remarkable effects on spontaneous activity. Motion distance was reduced, and the proportion of motionless time increased with increasing concentrations of PFOS. However, no significant alterations in the fast-start performance-related kinematic parameters, such as latency time, maximum linear velocity, maximum linear acceleration or escape distance during the first 120 msec after stimulus, were observed after PFOS exposure. Unexpectedly, although PFOS exposure had marked influences on the swimming oxygen consumption rates and AMR of goldfish, the U crit of the goldfish was not significantly affected by PFOS. This may result in a noteworthy increase in the energetic cost of transport. The overall results indicate that, in contrast to spontaneous activity, underlying swimming capabilities are maintained in goldfish after short-term exposure to PFOS, but energy expenditure during the process of swimming is dramatically aggravated.

Using spanwise flexibility of caudal fin to improve swimming performance for small fishlike robots

This paper examines the beneficial effects of the spanwise flexibility of the caudal fin for the improvement of the swimming performance for small fishlike robots. A virtual swimmer is adopted for controlled numerical experiments by varying the spanwise flexible trajectories and the spanwise flexible size of the caudal fin while keeping the body kinematics fixed. 3-D Navier-Stokes equations are used to compute the viscous flow over the robot. Elliptical, parabolic and hyperbola trajectories are chosen to describe the spanwise flexible profile of the caudal fin. According to the sign（positive or negative） of the phase difference of the swinging motion, the spanwise flexibility can be divided into the fin surface of ＂bow＂ and the fin surface of ＂scoop＂. It is observed that for both the fin surface of ＂bow＂ and the fin surface of ＂scoop＂, the spanwise elliptical trajectory has the optimal swimming velocity, thrust, lateral force, and efficiency. With comparisons, using the flexible caudal fin with the fin surface of ＂bow＂, the lateral force and the power consumption can be reduced effectively and the swimming stability can be increased while reducing little the swimming velocity and thrust. Meanwhile, using the flexible caudal fin with the fin surface of ＂scoop＂ can greatly improve the swimming velocity, thrust, and efficiency while increasing part of the lateral force and the power consumption. Three-dimensional flow structures clearly indicate the evolution process around the swimming robot. It is suggested that the fish, the dolphin, and other aquatic animals may benefit their hydrodynamic performance by the spanwise flexibility of the caudal fin.

Investigation of the hydrodynamic performance of crablike robot swimming leg

The existing amphibious robots cannot usually enjoy a superior adaptability in the underwater environment by replacing the actuators. Based on the bionic prototype of the Portunus trituberculatus, a new leg-paddle coupling crablike robot with a composite propulsion of walking legs and swimming legs is developed, with both the abilities of walking and swimming under water. By simulation and experiment, the effects of the phase difference, the flapping amplitude and the angular bias of the coupling movement, as well as the Strouhal number on the hydrodynamic performance of the swimming legs are studied, and the time dependent tail vortex shedding structure in a cycle is obtained. Both experimental and numerical results indicate that the thrust force with a high propulsion efficiency can be generated by a flapping swimming leg. This work can further be used for analysis of the stability and the maneuverability of the swimming leg actuated underwater vehicles.

Divergence and constraint in the thermal sensitivity of aquatic insect swimming performance

Environmental temperature variation may play a significant role in the adaptive evolutionary divergence of ectotherm thermal performance curves(TPCs).However,divergence in TPCs may also be constrained due to various causes.Here,we measured TPCs for swimming velocity of temperate and tropical mayflies(Family:Baetidae)and their stonefly predators(Family:Perlidae)from different elevations.We predicted that differences in seasonal climatic regimes would drive divergence in TPCs between temperate and tropical species.Stable tropical temperatures should favor the evolution of"specialists"that perform well across a narrow range of temperatures.Seasonally,variable temperatures in temperate zones,however,should favor"generalists"that perform well across a broad range of temperatures.In phylogenetically paired comparisons of mayflies and stoneflies,swimming speed was generally unaffected by experimental temperature and did not differ among populations between latitudes,suggesting a maintenance of performance breadth across elevation and latitude.An exception was found between temperate and tropical mayflies at low elevation where climatic differences between latitudes are large.In addition,TPCs did not differ between mayflies and their stonefly predators,except at tropical low elevation.Our results indicate that divergence in TPCs may be con strai ned in aquatic in sects except under the most differe nt ther・mal regimes,perhaps because of trade-offs that reduce thermal sensitivity and increase performance breadth.

SWIMMING PERFORMANCE ANALYSIS FOR ANGUILLIFORM PROPULSION

This paper investigates the swimming performance of fish undulatory motion which is the basic form in locomotion of aquatical animal from a hydrodynamics point of view.In particular,the propulsive characteristics is discussed.The three-dimensional potential flow over a model rectangular flexible plate performing the motion which consists of a progressive wave of a given wave length and phase velocity along the chord is treated.Vortex ring method is used to calculate the thrust,the power required and the hydrodynamic propulsive efficiency,etc.The dependence of these energetics on certain physical parameters,such as the aspect ratio,the reduced frequency and the wave number,is discussed.It is found that as the wave tength gets close to the body length,propulsive performance is no longer sensitive to the aspect ratio.Some qualitative explanation of the fish swimming phenomena is also given.

鱼类游泳能力综述:游泳速度、代谢成本及影响因素

了解鱼类的游泳能力对于鱼类资源保护和提升鱼类物种多样性有重要作用。关于鱼类游泳速度和代谢成本指标的研究结果表明,鱼类有氧游动和无氧游动之间既存在种内关系,也存在种间关系。通过回顾以往鱼类游泳能力相关研究,找出游泳速度、代谢成本和以温度、紊流为代表的外部影响因素的一般关系。结果表明:①鱼类游泳速度随着摆尾频率的增加而增加,而游泳速度、摆尾幅度和步长之间的关系尚未达成共识。②耗氧率和运输净成本均随鱼类游泳速度的增加呈指数或幂指数增加,而运输成本随游泳速度的增加呈“J”形指数关系。③随着温度的升高,临界游泳速度会呈现“钟”形或二次多项式曲线的变化趋势,相似地,耗氧率的变化也呈“钟”形曲线。④紊流对鱼类个体游泳能力的影响取决于涡体尺寸和鱼体大小的相对大小,对于鱼群的影响则取决于鱼群间个体间距、摆尾相位差和斯特罗哈数。

高水平男子400米个人混合泳运动员分段成绩的特征研究

400米个人混合泳是一项周期性体能项目,出色的游泳技术及合理的体能分配是运动员们在世界大赛中夺冠的关键。本文采用数理统计法对近五届世界游泳大赛上男子400米个人混合泳各分段成绩进行分析,以期探索各分段之间的关系,比较奖牌运动员与非奖牌运动员在竞赛分段成绩之间的差异,研究各分段成绩的特征及规律,为相关学者、教练们、运动员们提供实证参考。研究结果表明:①男子400米个人混合泳分段成绩与总成绩的高相关阶段为:蝶泳第2分段、100米蛙泳分段、100米蝶泳分段、仰泳第3分段、蛙泳第5分段、100米仰泳分段、蛙泳第6分段、自由泳第7分段、蝶泳第1分段、仰泳第4分段;②奖牌组与非奖牌组在各分段之间存在不同的程度的差异(P小于0.05),蛙泳阶段、自由泳阶段是男子400米个人混合泳运动员体能分配的关键阶段;③男子400米个人混合泳游进的策略为:蝶泳阶段负分游、仰泳阶段正分游、蛙泳阶段负分游、自由游阶段正分游,蝶泳阶段转仰泳阶段负分游,仰泳转蛙泳负分游,蛙泳转自由泳阶段正分游。

市售鱼鳔氨基酸及蛋白质成分分析

目的 分析16批不同基原的市售鱼鳔中氨基酸及蛋白质成分。方法 建立一种6-氨基喹啉基-N-羟基琥珀酰亚胺基甲酸酯柱前衍生、高效液相色谱法,测定鱼鳔中17种氨基酸含量,并对不同基原鱼鳔中氨基酸类成分进行分析;采用十二烷基硫酸钠聚丙烯酰胺凝胶电泳分析鱼鳔中的蛋白质分子量分布,并采用蛋白质组学法鉴定鱼鳔中的蛋白质。结果 17种氨基酸在一定浓度范围内线性关系良好(R2≥0.998 0),平均加样回收率85.62%~109.60%,精密度、稳定性、重复性RSD均小于3.5%。16批鱼鳔氨基酸组成与含量存在差异,氨基酸总含量介于468.31~620.05 mg/g;从16批鱼鳔中共鉴定688种蛋白质,包括Ⅰ型在内的胶原蛋白多达11种,此外,鱼鳔中还含有较多分子质量52~95 kDa的低丰度蛋白。结论 该研究可为鱼鳔的质量评价和开发利用提供参考。

蝠鲼交错排布集群游动水动力性能

为了探究蝠鲼“前上后下”交错排布集群游动时的水动力性能,首先根据生物观测建立了蝠鲼形态学及运动学模型,然后基于浸入边界法和球函数气体动理学格式(IB-SGKS)建立了鱼类集群游动数值计算方法.系统研究了垂直间距固定为0.1倍体厚,流向间距0—1.5倍体长(BL)下的双蝠鲼集群游动过程,并结合全局三维涡结构和特征截面二维涡结构对集群系统以及集群中各单体的平均推力/效率进行分析.数值结果表明:当单体间流向间距较小时,相比于单独游动,推进性能急剧下降;随着流向间距增加,领航蝠鲼推进性能基本同单体游动保持一致;但当Dx=0.4BL时由于领航蝠鲼尾涡恰好越过跟随蝠鲼前缘直接作用在跟随蝠鲼初始脱落鳍尖涡处,大幅提升其旋涡能量,因此此时系统平均推力和效率提升均最大,分别为29.69%和6.77%.

仿牛鼻鲼机器鱼倒游性能胸鳍结构设计与实验

现有基于摆动胸鳍推进方式的机器鱼有很多突出特点,特别是前向游动稳定性,但倒游性能研究不足,因此文中针对性地讨论摆动胸鳍推进模式的仿牛鼻鲼机器鱼倒游水动力性能。分别设计了完整胸鳍结构与分体胸鳍结构,通过对比实验测试验证了分体胸鳍结构较完整胸鳍结构倒游推力的优越性,通过推力和电流的比值进一步分析能耗转化效率。实验研究了前游和倒游推力与幅值和频率变化之间的关系,并且通过采集的电流数据,整理出2种胸鳍结构在前游和倒游工况下的推力等效效率与幅值和频率变化关系曲线;分析了2种胸鳍结构产生推力及推力等效效率的原因。实验结果表明:前游工况下,2种胸鳍推力值接近,倒游工况下,随着幅值和频率的增加,分体胸鳍结构倒游推力增加明显,最大可达0.22 N;前游工况下,分体胸鳍结构推力等效效率较完整胸鳍稍差,倒游工况下,随着幅值和频率的增加,分体胸鳍结构倒游推力等效效率有显著提升。文中对分体胸鳍结构的设计为探究基于摆旋机构推进机器鱼倒游性能提供了参考。

鳗鲡科鱼类变刚度特性对推进性能影响研究

生物学研究表明,波动推进鱼类的鱼体刚度对其推进性能有着重要影响,通过改变鱼体刚度可获得优异的游动特性,但鱼类肌肉驱动模式与鱼体刚度和游动性能的关系尚不清晰.鉴于此,文章以鳗鲡科鱼类作为研究对象,基于黏弹性梁理论和Taylor流体理论,建立由生物学钙离子肌肉驱动的鳗鲡科鱼类游动模型,研究肌肉驱动和鱼体刚度变化对推进性能的影响.结果表明,肌肉驱动力随刚度增加呈先快速增加后缓慢下降的变化趋势,而随着肌肉驱动力增加,鱼体游动速度随刚度增加而增加并逐渐趋于稳定.当肌肉驱动频率由1 Hz增加到2 Hz时,游动速度和启动加速度可分别提升55%和129%,可见增大鱼体刚度可显著提升推进性能.为了验证上述结论,设计了基于串并联结构的变刚度实验平台,实验表明鱼体的变刚度特性能显著提升推进性能.当舵机驱动频率由1 Hz增加到2 Hz时,通过统一变化弹簧刚度大小推力可提升2.5倍.上述研究结果可为改变鱼体刚度提升游动性能提供参数设计指导,为研制变刚度仿生机器鱼提供理论依据.

双鱼集群水动力和游动性能研究

为探索鱼类在群聚游动中水动力相互作用以及游动性能的影响,采用基于虚拟单元的锐利界面浸没边界法对双鱼以不同横向间距、纵向间距和尾摆相位差游动的问题进行了数值研究,并对双鱼的水动力性能和流场进行了综合分析。研究结果表明,在适当的位置和相应的尾摆相位差下,跟随鱼的游动性能可以得到显著的提高,同时影响领头鱼的游动性能。本文建议横向间距的最佳选择不应小于0.3倍体长。此外,通过考虑流场压力来探究双鱼间的水动力相互作用机制,发现双鱼间推力的产生同时受贴体压力和尾流动力的影响。分析表明,这两种影响的主导地位会随着双鱼间的位置变化而改变,当流向间距小于0.4倍的体长时,由贴体压力主导,当流向间距大于0.4倍的体长时,则改为由尾流动力所主导。这项研究可以为生物的集群游动力学机理提供一些见解,并支撑仿生潜航器的研制。

2013-2023年间浙江省青少年游泳比赛成绩变化趋势及两种成绩预测模型对比赛成绩预测效果的对比分析

采用数理统计法、预测分析法对2013-2023年间“迎春杯”浙江省青少年游泳锦标赛的成绩进行分析,以探讨2013-2023年间青少年游泳整体水平的发展变化情况。通过整合2013-2022十年间比赛成绩,采用灰色理论GM(1,1)预测模型和BP神经网络预测模型对2023年比赛冠军成绩和前八名平均成绩进行预测,将预测值和2023年比赛的实测值进行拟合对比,采用均方根误差(RMSE)和平均绝对百分比误差(MAPE)对两种模型的预测能力进行评定,探索更加有效的成绩预测方法,为今后备战重要比赛提供一定的理论参考依据。

基于变流速游泳训练的许氏平鲉幼鱼野化训练

为提升许氏平鲉鱼类资源,探究游泳训练对其生长的影响,以该物种为试验对象,开展了不同运动强度的游泳野化训练。以运动强度0为对照,设置4种运动强度,分别为50%、75%、125%和150%,训练30 d后测定其生长性能和生化指标,其中生长性能包括成活率、增重率、脏体比、肥满度和特定生长率;生化指标包括碱性磷酸酶(AKP)、过氧化氢酶(CAT)、谷草转氨酶(GOT)和溶菌酶(LMZ)活性及总氨基酸含量。生长性能结果显示,运动强度对幼鱼的成活率影响不大;与对照相比,不同运动强度明显提升了幼鱼的增重率、肥满度和特定生长率,降低了幼鱼的脏体比(P<0.05)。生化指标结果表明,与对照相比,50%运动强度明显增强了AKP、GOT和LMZ的活性,提高了总氨基酸含量(P<0.05);75%运动强度明显增强了AKP、CAT和LMZ的活性,提高了总氨基酸含量(P<0.05);125%和150%运动强度明显抑制了AKP和CAT的活性,增强了GOT和LMZ的活性,降低了总氨基酸含量(P<0.05)。综合以上结果表明,适度的游泳运动训练可以提高许氏平鲉幼鱼的生长性能和生化指标,改善肌肉品质,提高抗氧化和调节能力,促进幼鱼健康生长,以75%运动强度表现效果最佳。

第33届巴黎奥运会游泳项目奖牌分布及不同项群成绩特征分析

运用文献资料、录像观察、数理统计等研究方法,对第33届巴黎奥运会游泳项目奖牌分布及不同项群成绩特征进行分析。结果表明:(1)第33届巴黎奥运会游泳项目奖牌分布,主要集中在美国、澳大利亚和中国这三个国家,其他一些国家或地区虽然也在努力追赶,但相较于这三个领先国家,仍有显著差距。(2)在体能主导类速度性项群游泳项目中,美国和澳大利亚拥有众多高水平运动员,与其他国家拉开了一定的差距,中国队展现出强劲的竞争力,相较于上一届奥运会整体竞技实力有了显著提升。(3)在体能主导类耐力性项群游泳项目中,形成了美国队与澳大利亚队领先,法国队、加拿大队相互抗衡的竞争局面,中国队没有金牌入账。(4)在技能主导类难美性项群中,中国队夺得了全部10块金牌,具备强大的竞技实力和深厚的人才储备。(5)在技战能主导类同场对抗性项群水球比赛中,中国队乃至亚洲其他国家和地区的队伍与该项目的世界领先国家相比仍存在明显的差距。

第11-19届亚运会游泳成绩发展趋势研究--基于灰色GM(1,1)多维模型

以1990年北京至2023年杭州亚运会的历次游泳冠军成绩为时间序列,构建多维灰色GM(1,1)预测模型,探索亚运会游泳成绩内在规律和发展趋势,为各国备战2026年第20届亚运会及33届、34届奥运会提供参考。结果显示:①杭州亚运会游泳奖牌主要由中、日、韩获得,其中中国在亚洲泳坛占据顶尖地位,而浙江籍运动员是其中的重要力量。②第11-19届亚运会游泳成绩总体呈稳步提高趋势,且19届亚运会后游泳成绩仍将处于较快提高时期。③亚洲游泳与奥运游泳成绩差距总体呈缩小趋势,亚洲运动员在未来奥运会上将取得越来越好的成绩,其中在即将到来的巴黎奥运会上,预计中国男子在4×100m混合泳接力、200m自由泳和蛙泳项目中以及女子在蝶泳和个人混合泳项目中具备较大的夺金、夺牌潜力,应有针对性地加强这些项目的训练。

游泳技术改进的生物力学分析与应用

该研究通过生物力学的角度分析和应用游泳技术改进方法。首先,探讨了游泳动作的生物力学基础,包括力的分析、运动轨迹,以及水的阻力与推进力。其次,研究聚焦于通过数据驱动的技术分析和训练方法的生物力学优化来改进游泳技术。通过对高水平运动员的实证研究和案例分析,该文评估了基于生物力学的训练干预策略和技术改进效果。研究表明,综合运用生物力学原理可以显著提高游泳技术的效率和有效性。这为游泳运动员和教练提供了宝贵的指导,有助于提升运动表现和竞技水平。

Swimrun race,athletes,safety and performance:A brief review

Swimrun was established in Sweden in 2006.In competition athletes alternate between running and swimming multiple times.It has grown from only being hosted in Sweden to now being a global sport.The swimrun race exposes athletes to environments that require a unique set of skills.For example,participants have to negotiate ocean currents and waves.The environmental conditions change between the runs and the swims.Athletes may be exposed to hot temperatures when running in wetsuits(25℃and hotter)and cold water(colder than 16℃)when swimming.This sudden change in environmental conditions imposes a poorly defined physiological stress on the participants.Research on the demands of swimrun is scarce.More research is needed to improve athlete safety during events.Also,research is needed to provide insight into enhancing training methods and performance.