Swimming Ability Research Articles

Gyrotactic trapping of micro-swimmers in simple shear flows: a study directly from the fundamental Smoluchowski equation

Thin phytoplankton layers with vertically compressed structures found in stratified lakes and coastal water bodies have been a hot-spot in marine science and fluid mechanics. Although extensive efforts have been made to explore gyrotactic trapping as a possible mechanism, obvious inconsistencies remain there between the generalised Taylor dispersion method and individual-based model. In this work, a study directly from the fundamental Smoluchowski equation is carried out on the gyrotactic trapping mechanism in representative simple shear flows. With no approximation made to the fundamental equation and applying a biorthogonal expansion to the local moments of the probability density function, the evolution and steady state of the transport process are in good agreement with results of individual-based model, thus removing the gap between the continuum approach and individual-based model. The influences of strongly varying shear rate and boundary effect are reasonably scrutinised. The average swimming orientation with fixed local shear is highlighted as time-dependent rather than steady as previously assumed. The variations of characteristic time of the transient thin layer as functions of the flow intensity, gyrotaxis intensity and swimming ability are characterised. Sedimentation of the micro-swimmers is considered in some cases to reflect that micro-organisms are possibly negatively buoyant, with corresponding boundary conditions devised. A steady thin layer can be realised in the solution by adding a small settling speed to counteract the gravitactic focusing at the upper surface.

Molecular Characterization of Three Tandemly Located Flagellin Genes of Stenotrophomonas maltophilia.

Stenotrophomonas maltophilia is a motile, opportunistic pathogen. The flagellum, which is involved in swimming, swarming, adhesion, and biofilm formation, is considered a virulence factor for motile pathogens. Three flagellin genes, fliC1, fliC2, and fliC3, were identified from the sequenced S. maltophilia genome. FliC1, fliC2, and fliC3 formed an operon, and their encoding proteins shared 67–82% identity. Members of the fliC1C2C3 operon were deleted individually or in combination to generate single mutants, double mutants, and a triple mutant. The contributions of the three flagellins to swimming, swarming, flagellum morphology, adhesion, and biofilm formation were assessed. The single mutants generally had a compromise in swimming and no significant defects in swarming, adhesion on biotic surfaces, and biofilm formation on abiotic surfaces. The double mutants displayed obvious defects in swimming and adhesion on abiotic and biotic surfaces. The flagellin-null mutant lost swimming ability and was compromised in adhesion and biofilm formation. All tested mutants demonstrated substantial but different flagellar morphologies, supporting that flagellin composition affects filament morphology. Bacterial swimming motility was significantly compromised under an oxidative stress condition, irrespective of flagellin composition. Collectively, the utilization of these three flagellins for filament assembly equips S. maltophilia with flagella adapted to provide better ability in swimming, adhesion, and biofilm formation for its pathogenesis.

Quantitative uncertainty estimation in biophysical models of fish larval connectivity in the Florida Keys

Abstract The impacts of seven uncertain biological parameters on simulated larval connectivity in the Florida Keys are investigated using Polynomial chaos surrogates. These parameters describe biological traits and behaviours—such as mortality, swimming abilities, and orientation—and modulate larval settlement as well as dispersal forecasts. However, these parameters are poorly constrained by observations and vary naturally between individual larvae. The present investigation characterizes these input uncertainties with probability density functions informed by previous studies of Abudefduf saxatilis. The parametric domain is sampled via ensemble calculations, then a polynomial-based surrogate is built to explicitly approximate the dependence of the model outputs on the uncertain model inputs, which enables a robust statistical analysis of uncertainties. This approach allows the computation of probabilistic dispersal kernels that are further analyzed to understand the impact of the parameter uncertainties. We find that the biological input parameters influence the connectivity differently depending on dispersal distance and release location. The global sensitivity analysis shows that the interactions between detection distance threshold, orientation ontogeny, and orientation accuracy, are the dominant contributors to the uncertainty in settlement abundance in the Florida Keys. Uncertainties in swimming speed and mortality, on the other hand, seem to contribute little to dispersal uncertainty.

Swimbladder non-inflation and its influence on larviculture of mandarin fish (Siniperca chuatsi)

Low occurrence of swimbladder inflation often leads to vertebral skeletal malformations and poor swimming ability, which exert numerous effects on growth, feeding, buoyancy regulation and survival rate of fish larvae. In the present study, 713 mandarin fish (Siniperca chuatsi) larvae samples ranging from 5 to 11 days post hatch (DPH) were collected to detect the rate of swimbladder inflation and calculate the body density of each sample. Swimbladder inflated fish larvae were increased with the development of DPH except 7 DPH, with 86.21% in 11 DPH whereas 27.59% in 5 DPH. Our results indicate that 5–11 DPH is the main stage for swimbladder inflation in mandarin fish larvae, following the onset of exogenous feeding. The body density of swimbladder inflated (SBI) fish larvae (0.983 ± 0.016 g/cm3) was lower than the swimbladder non-inflated (SBN) ones (1.023 ± 0.018 g/cm3), while SBI fish larvae were significant heavier (p < 0.05) than SBN group. These findings suggest that swimbladder non-inflation could significantly influenced the neutrally buoyancy maintained and live bait predation in mandarin fish. The research will contribute to understanding the influence of initial swimbladder inflation on larviculture of mandarin fish.

Tropical larval and juvenile fish critical swimming speed (U-crit) and morphology data

Fish swimming capacity is a key life history trait critical to many aspects of their ecology. U-crit (critical) swimming speeds provide a robust, repeatable relative measure of swimming speed that can serve as a useful surrogate for other measures of swimming performance. Here we collate and make available one the most comprehensive datasets on U-crit swimming abilities of tropical marine fish larvae and pelagic juveniles, most of which are reef associated as adults. The dataset includes U-crit speed measurements for settlement stage fishes across a large range of species and families obtained mostly from field specimens collected in light traps and crest nets; and the development of swimming abilities throughout ontogeny for a range of species using reared larvae. In nearly all instances, the size of the individual was available, and in many cases, data include other morphological measurements (e.g. “propulsive area”) useful for predicting swimming capacity. We hope these data prove useful for further studies of larval swimming performance and other broader syntheses.

Hydrodynamic Characteristics of Remora’s Symbiotic Relationships

Symbiotic relationships have developed through natural evolution which can provide advantages to parties in terms of survival. For example, that of the remora fish attached to the body of a shark to compensate for their poor swimming ability. From the remora's perspective, this could be associated to an increased hydrodynamic efficiency in swimming and this needs to be investigated. To understand the remora's swimming strategy in the attachment state, a systematic study has been conducted using the commercial Computational Fluid Dynamics CFD software, STAR-CCM+ to analyse and compare the resistance characteristics of the remora in attached swimming conditions. Two fundamental questions are addressed: what is the effect of the developed boundary layer flow and the effect of the adverse pressure gradient on the remora's hydrodynamic characteristics? By researching the hydrodynamic characteristics of the remora on varying attachment locations, the remora's unique behaviours could be applied to autonomous underwater vehicles (AUVs), which currently cannot perform docking and recovery without asking the mother vehicle to come for a halt.

Sub-acute exposure to nanoplastics via two-chain trophic transfer: From brine shrimp Artemia franciscana to small yellow croaker Larimichthys polyactis

This study investigated the trophic transfer of nanoplastics in marine food chains. We fed nanoplastic-exposed Artemia franciscana (brine shrimp) to Larimichthys polyactis (small yellow croaker) daily for eight days. Subsequently, the overall health condition, histopathological damage to the liver and digestive tract, and swimming ability of the fish were measured. After the sub-acute exposure to nanoplastics via trophic transfer, the fish showed inhibited growth, severe liver damage, as well as a poorer swimming ability compared to the control. The swimming ability was especially affected, in terms of the overall movement as well as thigmotaxis. The results thus clarified that even an indirect exposure to nanoplastics could induce neurotoxic effects and affect the swimming ability of the fish. As fish are well-known human food resources, the possibility of such trophic transfers affecting higher trophic level organisms, such as humans, cannot be ruled out.

Ability to Swim (Not Morphology or Environment) Explains Interspecific Differences in Crinoid Arm Regrowth

Regrowth of body parts occurs in almost every phylum of the animal kingdom, but variation in this process across environmental, morphological, and behavioral gradients remains poorly understood. We examined regeneration patterns in feather stars – a group known for a wide range of morphologies and behaviors and up to a forty-fold difference in arm regeneration rates – and found that the variation in arm regeneration rates is best explained by swimming ability, not temperature, food supply, morphology (total number of arms and number of regenerating arms), or degree of injury. However, there were significant interactive effects of morphology on rates of regeneration of the main effect (swimming ability). Notably, swimmers grew up to three-fold faster than non-swimmers. The temperate feather star Florometra serratissima regenerated faster under warmer scenarios, but its rates fell within that of the tropical species suggesting temperature can account for intraspecific but not interspecific differences. We urge comparative molecular investigations of crinoid regeneration to identify the mechanisms responsible for the observed interspecific differences, and potentially address gaps in stem cell research.

Identifying risk factors and implications for beach drowning prevention amongst an Australian multicultural community.

Multicultural communities in Australia are recognised as a priority area for drowning prevention, but no evidence-based study has addressed their knowledge of beach safety. This study used an online survey tool to identify and examine risk factors relating to swimming ability, beach visitation characteristics and behaviour, and beach safety knowledge of the Australian Southern Asian community to assist in the development of future beach safety interventions. Data was obtained through 249 online and in-person surveys of people aged > 18 years. Most respondents reported poor swimming ability (80%), often swam in in the absence of lifeguards (77%), did not understand the rip current hazard (58%), but reported that they entered the water (76%) when visiting beaches. Close to one-quarter (28%) had not heard, or didn’t know the purpose, of the red and yellow beach flags, which identify lifeguard supervised areas on Australian beaches. Length of time living in Australia is an important beach safety consideration for this community, with minimal differences in terms of gender and age. Those who have lived < 10 years in Australia visit beaches more frequently and are less likely to have participated in swimming lessons, be able to swim, heard of the flags or swim between them, understand rip currents, or have participated in a beach safety program. Very few (3%) respondents received beach safety information from within their own community. The importance of beach safety education and swimming lessons within the Southern Asian community should be prioritised for new and recent migrants to Australia.

What makes children learn how to swim? – health, lifestyle and environmental factors associated with swimming ability among children in the city of Malmö, Sweden

BackgroundSwimming ability among children in the city of Malmö, Sweden is strongly affected by socioeconomic differences. We investigated to what extent mediating health and lifestyle factors, such as children’s eating, sleeping and physical activity habits, as well as the characteristics of the social and working environment at both school and home, could explain the socioeconomic gradient in swimming ability.MethodsOur study population included children who started their first-grade school-year in 2012 or 2013 at any of the public primary schools of Malmö, Sweden. Cross-sectional, self-reported questionnaire-based data about health status and swimming ability in the fourth grade (age 10) were included from the Pupil Health Database (ELSA) for 3468 children.ResultsChildren’s self-reported swimming ability was strongly associated with both individual- and school-based sociodemographic variables. Nine health, lifestyle and environmental variables were identified as potential mediators and included in the final model. Four of these variables, “Activity”, “Outdoor time”, “Social relationships at home and on the free time”, and “Positivity about future”, were significantly and positively associated with children’s ability to swim.ConclusionsSocial support, optimism for the future and an active lifestyle were positively associated with children’s swimming skills; however, compared to the socioeconomic factors, these health- and lifestyle factors contributed very little. It is possible, that interventions concerning children’s swimming ability in lower socioeconomic neighbourhoods, should in addition to children’s swimming lessons, target the whole families with the goal of increasing their possibilities for socialising and engaging in different kinds of recreational activities.

Relationships between male secondary sexual traits, physiological state and offspring viability in the three-spined stickleback

BackgroundSexual signals produced by males play a central role in sexual selection, but the relationship between these traits and the quality of the bearer are often ambiguous. Secondary sexual traits may represent genetic quality of the bearer, resulting in positive relationships with physiological state, or may be costly to produce, showing trade-off with physiological state. A number of studies have explored the relationships between secondary sexual traits and other functional traits, but few have studied their fitness consequences. We studied the link between diverse physiological traits and both morphological and behavioural sexual traits and examined how their interplay influences offspring viability in the three-spined stickleback.ResultsMale sticklebacks showing nest building and courtship behaviour were smaller than those not investing in reproductive activities. There was no evidence that the expression of red nuptial colouration and the quality of courtship behaviour of males are positively related to their metabolic rates, swim ability, oxidative damage and mtDNA copy number. However, individuals showing larger red nuptial colour areas had higher levels of oxidative DNA damage in their sperm. Male courtship behaviour and aggressiveness, but not red colour area, were good predictors of offspring hatching and survival.ConclusionsOur results suggest that, in our study population at the southern edge of the species’ distribution, sexual colouration of male sticklebacks was not a good indicator of their body state, but both courtship quality and aggressiveness during the courtship are reliable cues of their gamete quality, influencing the viability of their offspring. Thus, females that choose mates based on their courtship behaviour will have high fitness. In the study population, which represents a fast pace-of-life with high reproductive rate and short lifespan, sexual ornaments of males may not honestly signal their physiological and physical state because they invest at maximum in a single reproductive season despite high costs.

Habitat destruction in wetland affects Ostracoda (Crustacea) species occurrence patterns amid different aquatic habitats.

To outline influence of anthropogenic activities on natural aquatic habitats such as wetlands, we sampled ostracods along with measuring several different aquatic variables at four different aquatic bodies between 2019 and 2020 in the Hıdırşeyhler Village (Bolu, Turkey). We found 15 living and 10 subfossil ostracods. Species with high tolerances (Eucypris virens) and/or with swimming abilities (Cypria ophtalmica) were reported from the canal and wetland. Non-swimmer ostracods (e.g., Prionocypris zenkeri) were only found from the creek. Ostracod Watch Model illustrated some species with stenochronal and eurychronal (e.g., Heterocypris incongruens) occurrences per site. CCA results displayed that water temperature and electrical conductivity were the most important explanatory variables on species. Unbiased diversity indices revealed the highest diversity in the canal followed by the creek, wetland, and trough. Wetland diversity exhibited positive and negative correlations with the canal and the creek, respectively. Tukey’s pairwise test supported the significant comparisons between the trough, canal, and wetland (p < 0.01). The ratio of tolerant species per station was slightly higher in the canal than the wetland, trough, and creek. This suggests the fact that species encountered from the creek seem to be habitat specific and may be considered more vulnerable to changes in aquatic conditions. Frequency of species encountered in three habitats (wetland, canal, and trough) was significantly changed after the construction (digging and converting the wetland) activities began in August 2019. This activity was a negative impact on species diversity and richness in the wetland area where the diversity sharply dropped down and did not recover during the study. In contrast, this was probably advantage for some cosmoecious species.

Pseudomonas aeruginosa-accelerated corrosion of Mo-bearing low-alloy steel through molybdenum-mediating chemotaxis and motility

In this work, we found that the microbiologically influenced corrosion of Pseudomonas aeruginosa was mediated by Mo in low-alloy steel. Through immersion experiments, we found that the corrosion rate of low-alloy steel was not decreased with the addition of 1.0 wt% Mo. However, in the presence of P. aeruginosa, the corrosion rate of the 1.0 wt% Mo steel was accelerated, resulting in the development of pits. Confocal laser scanning microscopy images revealed that more biofilm cells adhered on the 1.0 wt% Mo steel surface. The chemotactic behavior and swimming ability of the bacteria were the main reason for the greater biofilm cell adhesion in the presence of Mo. Using an RNA-seq assay, we verified that both chemotaxis and motility together affected the adhesion of biofilm, and their related genes were affected by Mo.

Comprehensive analysis and application of Chinese Cyprinidae swimming ability

该研究利用学术论文数据库筛选出中国鲤科鱼类游泳能力相关论文115篇，并用Origin软件进行了数据统计分析，旨在归纳和分析中国鲤科鱼类游泳能力并建立估算方法，可为正处于规划阶段和可行性研究阶段的过鱼设施流速设计提供依据.结果表明：（1）鱼类游泳速度与鱼体长度具有显著的非线性相关关系，据此建立了一系列幂函数经验公式，可为游泳能力和过鱼设施研究及设计提供依据.（2）依据所得到的经验公式和协方差分析可知，喜流水型鲤科鱼类的游泳能力>广适型>喜静水型.根据该研究得到的经验公式并结合行业规范和文献资料，对正处于规划阶段和可行性研究阶段过鱼设施流速设计的建议如下：西南地区以裂腹鱼成鱼为主要过鱼对象的过鱼设施进鱼口吸引流速范围为0.61~0.76 m/s，通道内最高流速阈值为1.28 m/s；长江中下游以四大家鱼成鱼为主要过鱼对象的进鱼口吸引流速范围为0.76~0.93 m/s，通道内最高流速阈值为1.49 m/s，以四大家鱼幼鱼为主要过鱼对象的进鱼口吸引流速范围为0.42~0.62 m/s，通道内最高流速阈值可为0.82 m/s.;In order to provide an estimation method and basis for the fish swimming ability and for the flow velocity design of fish passing facilities in the planning stage and feasibility stage, by searching the papers related to the swimming ability of Chinese Cyprinidae from the internationally recognized academic paper network database, we selected 115 and then compared them with the critical swimming speed, burst speed and total length as describing indexes by using software Origin 9.0. Results indicated:(1) The relationship between fish swimming speed and fish length is allometric rather than isometric. It is recommended that the power function can be used to fit the correlation between fish swimming speed and total length. (2) Based on the empirical formula and the covariance analysis, swimming ability of rheophilic Cyprinidae > swimming ability of semi-rheophilic Cyprinidae > swimming ability of limnophilic Cyprinidae. According to the Design code for fish passage facilities in hydropower projects in China, Guideline for fishway in water conservancy in China and literature references about fish passage facility design, as well as the empirical formula in this study, the flows for fish passing facilities in the planning and feasibility stages in southwest China and the middle and lower reaches of the Yangtze River were recommended as follows. In the southwest China, the attraction flow velocity range of the fish passing facility entrance with adult Schizothoracinae fishes as the target species is 0.61-0.76 m/s, and the maximum velocity of the passage and pool is 1.28 m/s. In the middle and lower reaches of the Yangtze River, the attraction flow velocity range of the fish passing facility entrance with adult four major Chinese carps as the target species is 0.76-0.93 m/s, and the maximum velocity of the passage and pool is 1.49 m/s. The attraction flow velocity range of the fish passing facility entrance with juvenile four major Chinese carps as the target species is 0.42-0.62 m/s, and the maximum velocity of the passage and pool is 0.82 m/s.

A morphologically abnormal example (shortened anal fin) of Masturus lanceolatus from Japan and testing its effect on swimming ability by underwater remote control robot

A morphologically abnormal example (shortened anal fin) of <i>Masturus lanceolatus</i> from Japan and testing its effect on swimming ability by underwater remote control robot

КОНСТРУКТИВНЫЕ РЕШЕНИЯ ЗОН ОТДЫХА РЫБ НА ПРЯМОЛИНЕЙНЫХ УЧАСТКАХ РЫБОХОДНЫХ КАНАЛОВ

Purpose: to develop structural solutions for recreation areas for fish, arranged on straight sections of fish channels. Materials and methods. The empirical basis for the development was the data of studies carried out on the existing fish passage channels and fish passage locks of the Don cascade of low-head river hydroelectric facilities, as well as materials from known and author's studies of the swimming ability and behavioral characteristics of anadromous migratory fish. When processing experimental data, methods of analysis and synthesis of experimental material were used, and when developing constructive solutions for recreation areas, experimental design technologies were used. Results and discussion. The initial materials of research on the existing fish passage structures (fish passage locks and fish passage channels) determined the need for construction of recreation areas for fish migrating through them in the fish passage channels. Structurally, recreation areas are formed by the arrangement of deepened or expanded sections of fish channels tracts, which makes it possible to reduce the flow velocities in them, increase the volume of living space and create conditions for restoring the energy potential of migrating aquatic organisms. The geometrical parameters and hydraulic characteristics of fish resting areas depend on the totality of interrelated morphometric and hydrological conditions of the canal tracts (determining the navigational conditions of migratory movement) and the biological features of anadromously migratory fish (mainly determined by swimming ability). Conclusions. General provisions for the design of recreation areas for fish are formulated, and their typical deepened, expanded and combined design solutions for the conditions of straight tracts of fish passages are developed. A typical solution for a different-depth and extended design of a recreation area has been tested (adapted) for fish-breeding, biological, topographic and hydrotechnical conditions of the Kochetovsky fish passage channel.

鄱阳湖水利枢纽工程建设对草鱼江湖洄游潜在的影响

鄱阳湖是长江四大家鱼索饵、育肥的重要场所, 近年来鄱阳湖出现了枯水季水位严重降低、枯水期延长、湿地面积缩小的现象。为解决鄱阳湖水资源、水文、水生态等问题, 建议在鄱阳湖入江水道兴建控制闸水利枢纽。然而, 拟建的水利枢纽工程将打破鄱阳湖与长江的天然连通性, 可能会对四大鱼类洄游过程产生影响。通过构建二维和三维水动力模型, 分析鄱阳湖水利枢纽建设后入江水道与枢纽洄游通道的水动力学特征, 结合实验和文献获得的草鱼幼鱼和成鱼游泳能力参数, 阐明了枢纽建设对草鱼洄游的影响。结果表明: 在设计调度模式下, 草鱼幼鱼入湖期间, 湖口段适宜通过天数达到83.74%以上, 说明湖口及入江水道的水动力条件对洄游的影响较小, 同时, 枢纽工程处在过鱼高峰期仍能保持较高的过闸效率; 草鱼成鱼出湖期间, 丰、平水年闸前水动力条件对洄游的影响较小, 仅在枯水年闸前流速几乎静止, 草鱼适宜出湖天数偏低。在该调度模式下, 水利枢纽建设运行后鄱阳湖整体水动力条件能够满足草鱼洄游需求。目前设计的鱼道在高、低水位时期均出现局部流速过大的现象, 不满足过鱼条件。从四大家鱼江湖洄游的角度为鄱阳湖水利枢纽工程设计和运行提供科学参考。;Poyang Lake serves as the main feeding and fattening venue for the four major Chinese carps. In recent years, Poyang Lake has experienced a severe drop in water level during the dry season, prolonged dry season, and reduced wetland area. To tackle the problem of water resources, hydrology and water ecology in Poyang Lake, it is suggested to build a hydro-junction project which is proposed to be located at the channel connecting the Poyang Lake and the Yangtze River. Yet the to-be-built Poyang Lake Hydro-junction Project would impede the natural connection between Poyang Lake and the Yangtze River. The migration passage of the four major Chinese carps may be affected. To study the potential impact of the prospective hydro-junction project on the migration of grass carp, analysis was conducted on the hydrodynamic characteristics of the migration channel after the construction of Poyang Lake Hydro-junction Project using two-dimensional and three-dimensional hydraulic models. The swimming ability of grass carp was determined through experiment and literature review. According to the study results, more than 83.74% of the days suitable for fish passage at the entrance to the lake. The hydrodynamic conditions at the entrance and the channel into the Yangtze River had an insignificant impact on the fish migration at the time when the juvenile grass carps entered the lake. Meanwhile, the gate chamber of hydro-junction project could still maintain a high passing efficiency during the peak period of fish migration. While under the designed scheduling mode, the hydrodynamic conditions in front of the hydraulic construction had little effect on fish migration in the years of wet and normal, but the days that were favorable for the fish departure from the lake decreased in dry years caused by almost static velocity in front of the hydraulic construction when the adult grass carps left the lake. The overall hydrodynamic conditions of Poyang Lake could meet the needs of the grass carp migration during the operation period of the Poyang Lake Hydro-junction Project. However, the current design of the fishway of the Poyang Lake Hydro-junction Project suffered the excessive flow velocity in some parts during high and low water level period, which dissatisfied the required passage conditions based on fish swimming ability under the existing scheduling mode. This study was expected to provide a scientific reference for the design and operation of the Poyang Lake Hydro-junction Project from the perspective of river-lake migration of the four major Chinese carps.

The study of Effection and Satisfaction of Junior high School Students' Swimming Learning in Taichung City

&lt;p&gt;目的：以臺中市國中生游泳學習為研究標的，游泳池為研究場域，藉以探討學習成效與學習滿意度之關係。方法：係參酌國內相關領域學者研究發展之量表，依研究目的所編修之「國中生游泳學習成效與學習滿意度調查問卷表」為研究工具。於2020年6月針對國中生進行立意抽樣問卷調查，共計發出550份問卷，回收有效問卷521份，有效回收率達95%。結果：(一)整體學習滿意度與學習成效構面皆趨於正向，且以「教師專業」與「技能學習」為最高。（二）國中生之性別在學習滿意度之「教師專業」上及學習成效之「認知學習」與「技能學習」上有顯著差異，且女生在教師專業上明顯高於男生。（三）國中生之年級在學習滿意度上有顯著差異，且3年級明顯高於1年級。（四）國中生之游泳能力在學習成效上具顯著差異。（五）國中生之學習滿意度與學習成效具有顯著關係。結論：建議游泳池經營管理部門應持續強化教練專業知能，同時精進學習環境、場地設施及課程安排，以提升學習滿意度與成效。&lt;/p&gt; &lt;p&gt;&amp;nbsp;&lt;/p&gt;&lt;p&gt;Purpose: The purpose of this study was to investigate the latent relationships among learning satisfaction and learning effectiveness. Method: The researchers refer to the research and development scales of scholars, and the &amp;quot;Questionnaire for Swim Learning Satisfaction and Learning Effectiveness of Junior High School Students&amp;quot; compiled by the research objectives as a research tool. In May 2020, a questionnaire survey was conducted against junior high school students. A total of 550 questionnaires were sent out, and 521 valid questionnaires were recovered, with an effective recovery rate of 95%. Results: (1) The overall learning satisfaction and learning effectiveness tend to be positive that focus on &amp;quot;teacher profession&amp;quot; and &amp;quot;teacher profession&amp;quot; (2) The gender of junior high school students has significant differences in the &amp;quot;teacher profession&amp;quot; of learning satisfaction and the &amp;quot;cognitive learning&amp;quot; and &amp;quot;skill learning&amp;quot; of learning effectiveness. (3) The grades of junior high school students have significant differences in learning satisfaction. (4) The swimming ability of junior high school students has significant differences in learning effectiveness. (5) The learning satisfaction of middle school students has a significant relationship with learning effectiveness. Conclusion: It is recommended that the management department should continue to strengthen the professional knowledge of coaches, and at the same time improve the learning environment, venue facilities and curriculum arrangements to improve learning satisfaction and effectiveness.&lt;/p&gt; &lt;p&gt;&amp;nbsp;&lt;/p&gt;

Dietary shifts and niche partitioning throughout ontogeny reduce intraspecific competition in a pelagic generalist predator

Patterns of feeding strategy change throughout ontogeny according to size-specific abilities and requirements. Characterizing the extent and potential repeated occurrence of dietary differences within the population can improve understanding of the intraspecific predation regime and population dynamics. Here, we investigated size-related feeding habits and trophic niche partitioning of an iconic pelagic generalist predator, the jumbo squid Dosidicus gigas, by a combined analysis of morphologic indicators of feeding capability (fin and feeding apparatuses), trophic biochemical tracers (stable isotopes and fatty acids), and stomach contents. Results showed significant variation in prey composition, isotopic values, and fatty acid profiles with size. D. gigas exhibited a shift in diet at approximately 250 mm mantle length (ML). The trophic niche of small (ML ≤ 250 mm) and large (ML &gt; 250 mm) squid revealed low potential for resource overlap, suggesting segregation in terms of spatial and food resources of different size groups. Large individuals tend to feed deeper and on smaller prey to optimize food capture costs and energy benefits. This feeding strategy is likely related to variability in the development of feeding capacity, increasing swimming ability, and metabolic demand as squid grow and may reduce intraspecific competition to improve survival. These results highlight the dietary flexibility of D. gigas and demonstrate that niche differentiation acts as a major factor in a cohort, which may have important implications for their population dynamics and management. In addition, this study demonstrates that using multiple diet tracers can highlight subtle differentiations in diet correlated to growth in a pelagic generalist predator.

Swimming ability of fifteen target fish from eight hydropower stations in China

近几年我国水电站过鱼设施设计已将过鱼对象游泳能力作为重要参考. 以我国8个水电站主要过鱼对象为研究目标，在野外实验设施条件下测试了15种鱼(四大家鱼组、裂腹鱼组和鳅组)的感应流速和爆发游泳速度. 采用多元线性回归法分别分析了各组鱼体长及水温对游泳能力的影响，并构建了优化的游泳能力预测模型. 结果表明，四大家鱼组、裂腹鱼组和鳅组的感应流速和爆发游速皆与体长呈负相关，感应流速与水温也皆呈负相关关系. 水温升高使四大家鱼组和裂腹鱼组的爆发游速能力增强，而水温对鳅组鱼的爆发游速影响不大，可能与鳅科鱼类特殊的腹部吸附行为有关. 利用绘制的鱼感应水流和爆发未疲劳的数量百分比的生存曲线进行上行及下行过鱼设施流速设计. 结果表明：当鱼感应水流的数量百分比为90 % 时，四大家鱼、裂腹鱼和鳅组幼鱼感应流速分别为3.00、1.67和3.22 BL/s，裂腹鱼和鳅组成鱼感应流速分别为1.27和2.09 BL/s；当鱼爆发未疲劳的数量百分比为90 % 时，四大家鱼、裂腹鱼和鳅组幼鱼爆发游泳速度分别为8.13、9.27和9.61 BL/s，裂腹鱼和鳅组成鱼爆发游泳速度分别为7.64和7.77 BL/s. 当以裂腹鱼或鳅成鱼为主要过鱼对象时，上行过鱼设施内流速范围建议为1.27~7.64和2.09~7.77 BL/s. 当以四大家鱼、裂腹鱼或鳅幼鱼为主要过鱼对象时，下行过鱼设施入口流速建议小于8.13、9.27和9.61 BL/s. 本研究结果可为我国水电站主要过鱼对象的过鱼设施设计提供参考依据.;In recent years, the design of fish passage has taken the swimming capacity of target fish as an important criterion. Fifteen fish species from eight hydropower stations in China, including the four major Chinese carp, Schizothorax and Cobitidae, were selected as target species. Swimming capability was assessed by measuring induced flow velocity (U_ind) and burst swimming speed (U_burst) under identical test conditions. The relationship between U_ind (or U_burst), water temperature (T) and body length (BL) was assessed using multiple linear regression models and the optimal prediction model of swimming capability was constructed. U_ind and U_burst were negatively related to body length, while temperature effect between U_ind and U_burst varied between the three target fish species: U_ind was negatively related to temperature; U_burst was increased with the temperature for the four major Chinese carp and Schizothorax, while the temperature had little effect on U_burst of Cobitidae, which may be related to the special abdominal adsorption behavior of this fish. The percentage of fish either induced to swim (U_ind) or that were not exhausted (U_burst) was plot using survival curves, which was used to set fish passage design criteria. The result showed that 90 % of fish induced to swim were 3.00 BL/s for juvenile four major Chinese carp, 1.67 and 1.27 BL/s for juvenile and adult Schizothorax, 3.22 and 2.09 BL/s for juvenile and adult Cobitidae, respectively. The 90 % of fish were not exhausted were 8.13 BL/s for juvenile four major Chinese carp, 9.27 and 7.64 BL/s for juvenile and adult Schizothorax, 9.61 and 7.77 BL/s for juvenile and adult Cobitidae, respectively. The recommended pool velocity range of fish passage for upper migration was 1.27-7.64 BL/s for adult Schizothorax and 2.09-7.77 BL/s for adult Cobitidae, respectively. The inlet velocity of fish passage for downstream migration was recommended to be less than 8.13, 9.27 and 9.61 BL/s for juvenile four major Chinese carp, juvenile Schizothorax and juvenile Cobitidae, respectively. The results are helpful for the design of fish passage for the main target fish of hydropower stations in China.