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Purpose: Open-water swimmers need to train with wetsuits to get familiar with them; however, body core temperature (Tcore) kinetics when using wetsuits in swimming-pool training remains unclear. The present study assessed the effects of wetsuit use in pool training on Tcore, subjective perceptions, and swimming performance to obtain suggestions for wearing wetsuits in training situations. Methods: Four elite/international-level Japanese swimmers (2 female, age 24 [1] y) completed two 10-km trials with (WS) and without wetsuit (SS) in the swimming pool (Tw: 29.0 °C). During the trial, swimmers were allowed to remove their wetsuit if they could no longer tolerate the heat. Tcore was continuously recorded via ingestible temperature sensors. Swimming speed was estimated from every 100-m lap time. Results:Tcore increased by distance in both trials in all swimmers. Tcore when swimmers removed their wetsuit in the WS (distance: 3800 [245] m, time: 2744 [247] s) was higher than that at the same distance in the SS in all swimmers. Rating of perceived exertion was higher in the SS than the WS, and swimming speed was slower in the WS than the SS in all swimmers. Conclusion: Wetsuit use during pool training increases Tcore and decreases swimming performance. Although wearing wetsuits in training situations is important for familiarization, for the safety of the swimmers, it is recommended that they remove their wetsuit if they feel too hot. [ABSTRACT FROM AUTHOR]

Margalefidinium polykrikoides is a mixotrophic dinoflagellate harmful algal bloom (HAB) species that blooms annually in the lower Chesapeake Bay. M. polykrikoides undertakes a diel vertical migration (DVM) which may give it a competitive advantage over purely phototrophic organisms who cannot access deeper nutrient pools and allow it to form large toxic blooms. Laboratory-based estimates of M. polykrikoides' DVM rates suggest that it is one of the fastest known dinoflagellate swimmers and understanding this behavior is likely important for modeling and predicting M. polykrikoides blooms. However, to date, no field-derived estimates of M. polykrikoides' DVM rates have been made in the Chesapeake Bay. In this study, we conducted four targeted field experiments to investigate the DVM of M. polykrikoides in the Lafayette River, a sub-tributary of the Chesapeake Bay. Vertical profiles of chlorophyll a fluorescence collected at least every 2 h over diel periods were used to track the DVM of M. polykrikoides during blooms. The maximum observed DVM rate for M. polykrikoides was 2.5 m h−1, with mean DVM rates around 1.3 m h−1 for both ascents and descents. As in studies from other regions, our results show that M. polykrikoides' ascent to/descent from the surface initiates before sunrise/sunset, suggesting phototaxis is not the primary trigger of their DVM. However, unlike in other studies where M. polykrikoides was observed to modulate its DVM to avoid excessively warm temperatures (≥30°C), we do not observe active thermotaxic avoidance, despite ambient temperatures exceeding their optimal threshold. [ABSTRACT FROM AUTHOR]

Fish swimming speed is a standard measurement used for assessing the environment and behavior of fish in aquaculture. However, methods involving propeller-type data loggers, ultrasonic telemetry, and cameras have some limitations. Estimates of swimming speed by cameras are based on swimming trajectories; however, obtaining the swimming trajectories is difficult because the relative positions of the camera and fish body change owing to wave effects. The aim of this study was to describe and present a novel method to estimate the swimming speed of masu salmon (Oncorhynchus masou) influenced by artificially generated waves. Tail-beat frequency was estimated from periodic changes in fish length measured using a stereo camera. The swimming speed was estimated from tail-beat frequency according to the relationship between them as obtained by camera measurement; we found that a fixed stereo camera can help estimate tail-beat frequencies. The estimated data from the moving stereo camera were within the 95% prediction interval of the swimming speed estimation model constructed using the fixed stereo camera. Our study proves the potential of this method in aquaculture. Overall, this approach is a novel method to estimate the swimming speed influenced by wave conditions. In the future, this method can be automated for the identification of abnormal behaviors and detection of malformed fish. [ABSTRACT FROM AUTHOR]

Copyright of Retos: Nuevas Perspectivas de Educación Física, Deporte y Recreación is the property of Federacion Espanola de Asociaciones de Docentes de Educacion Fisica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Estimating tailbeat frequency (TBF) is a crucial component of fish swimming kinematics and performance, particularly because it provides information about energetics and behavioral responses to environmental cues. The most commonly used technique for TBF estimation is based on accelerometers. This paper proposes a novel approach using bioimpedance technology. This is the first time bioimpedance has been measured in a freely moving animal. This was made possible by implanting a flexible electrode in the back muscle of seabasses and having them in a swimming tunnel. The experiment first demonstrates that it is possible to measure bioimpedance in an immersed fish despite the high conductivity of seawater. An agreement analysis was then performed to compare a video-based reference measurement of TBF with the newly proposed approach. Several bioimpedance settings, such as the configuration and the extracted electrical parameters, were considered. Data analysis highlights that a 4-point setup for modulus impedance measurement at frequencies over 10 k Hz provides the best agreement (r > 0.98 and CCC > 0.97) with the video-based approach. These results attest to the significant benefits of integrating bioimpedance sensors in biologgers, especially considering the complementary parameters that can be extracted from bioimpedance measurements, such as length, weight, condition index, and fat content. [ABSTRACT FROM AUTHOR]

Although usually considered part of the plankton, cubozoans are strong swimmers. The aim of this study was to determine the influence of the active swimming ability of the box jellyfish Carybdea marsupialis on the spatial distribution of a well‐studied population in the NW Mediterranean where adults and juveniles do not overlap geographically. To accomplish this, we analyzed the swimming speed, effective velocity, effective displacement index (EDI), and proficiency of 27 individuals with diagonal bell widths (DBWs) ranging from 1.1 to 36 mm. The laboratory analysis utilized conventional video recordings and the video analysis tool Tracker. Mean swimming speed for small juveniles, medium juveniles and adults was 9.7 ± 0.8, 21.9 ± 2.3 and 43.1 ± 1.8 mm s−1 (mean ± se), respectively. Effective velocity was also proportional to size, ranging from 5.0 ± 0.7 to 38.8 ± 3.1 mm s−1 (mean ± se). The calculated EDI for each group was 0.51 ± 0.05, 0.84 ± 0.06 and 0.90 ± 0.05 (mean ± se), respectively. Proficiency showed an inverse trend, from 6.4 ± 0.6 s−1 for the small juveniles to 1.36 ± 0.05 for adults (mean ± se). Comparing the swimming speed results with the local currents obtained from drifting buoys analyzed in the area, adults would be able to swim strongly enough to overcome almost 70% of the currents, whereas the small juveniles would not reach 17%. This would allow larger individuals to select their habitat, while smaller individuals are left dependent on advection. Although experiments adding currents in aquaria would be necessary to confirm these theoretical results, the data obtained would be useful in improving the performance of bio‐mathematical models used to predict jellyfish blooms since, even though the sting of C. marsupialis is non‐fatal, it may produce systemic effects in sensitive swimmers. [ABSTRACT FROM AUTHOR]

Approach: Intermittent incremental tests (ITT), intermittent tests (IT), and continuous tests (CT) provide physiological parameters along with the corresponding swimming speeds (v), which are valuable for decisionmaking by coaches. Purpose: This study aimed to summarise and compare the effectiveness of ITT, IT, and CT in monitoring physiological parameters -- oxygen uptake (VO2), the blood lactate concentration ([La-]), and heart rate (HR) -- as well as their associated v. Methods: The PubMed, EMBASE, and Web of Science databases were searched for complete studies published in English, from 1 January 2000 to 24 January 2024. Eleven studies (n = 164 swimmers) fulfilled the inclusion criteria. A meta-analysis was performed. Results: The results of the studies were homogeneous (p > 0.05) when v was also similar between the tests: ITT compared with CT (7 studies, n = 88 swimmers) VO2 0.03 ± 0.15 mL·kg-1·minute-1, I² = 0%, p = 0.99; v 0.08 ± 0.14 m·s-1, I² = 0%, p = 0.89; IT compared with CT (3 studies, n = 44 swimmers) [La-] 0.12 ± 0.21 mmol·L-1, I² = 0%, p = 0.64; HR -0.32 ± 0.2 beats·minute-1, I² = 0%, p = 0.37; v 0.08 ± 0.14 m·s-1, I² = 0.00%, p = 0.89). Conclusions: The VO2 results for the comparisons between IT and CT, and the [La-] and HR results for comparisons between IT and CT were similar when: (i) the v was also similar between the tests, and (ii) the duration of the tests was long enough to obtain more stable physiological data. [ABSTRACT FROM AUTHOR]

Predation is a well-known factor that structures rotifer communities. However, the role of protists as predators is relatively understudied. Here, we investigated predatory behavior of Actinosphaerium sp., a freshwater heliozoan, on seven rotifer species. Predators and prey were collected from a local playa; except for Brachionus calyciflorus that served as a naive prey control. Prey included large species (≥ 175 µm mean length: Asplanchna sieboldii, B. calyciflorus, Platyias quadricornis, and Lacinularia flosculosa) and small species (< 175 µm: Cephalodella gibba, Euchlanis dilatata, and Lepadella patella). Four experiments were conducted. (1) Single prey items of varying size and motility. Larger prey types were ~ 1.7 to 3.0 times more likely to be ingested than small prey. No L. flosculosa were ingested, contrary to field observations. No correlation was found between swimming speed and predation risk. (2) Preference tests. Asplanchna sieboldii and B. calyciflorus were favored prey. (3) Growth rate of Actinosphaerium on mixed diets, with and without Asplanchna. Highest population growth of Actinosphaerium was observed in presence of A. sieboldii. (4) Prey defenses. Susceptibility of spined versus unspined B. calyciflorus resulted in no significant difference in predation risk. Thus, size and being mobile (compared to sessility) are the primary risk factors influencing rotifer predation vulnerability. [ABSTRACT FROM AUTHOR]

In the process of ascending and descending in deep-sea submerging and lifting cage nets, accompanied by changes in water pressure, pressure is one of the crucial environmental factors affecting the physiology and growth of fish. It directly relates to the comfort of farmed fish in the cage, thereby influencing the quality of aquaculture, especially for high-demanding species on the culture environment like the Larimichthys crocea. Investigating the stress level changes exhibited by L.crocea under environmental pressure variations, understanding the limit tolerance pressure, and its changes, can provide a theoretical basis for the design, application, and increased production of deep-sea submersible cage nets and L.crocea aquaculture. This study explores the effects of varying submersion depths (0–20 m) and speeds (0.6, 1, 1.3, 2, 4 m/min) on the behavioral responses of L.crocea in deep-sea cage environments. Key findings demonstrate that increased submersion depths and speeds significantly influence the physical behaviors and stress responses of the species. At submersion depths of 15 meters and 20 meters, the average swimming speed of the L.crocea exceeds 0.05 meters per second, the tail movement frequency is 1.42 times that of normal pressure, and the gasping frequency exceeds 20%., and at the highest speed of 4 m/min, the swimming speed reaches 0.0902 m/s—3.76 times greater than under normal pressure. The study determines that a submersion depth of 10 meters and a submersion speed of 0.6 meters per minute can minimize stress responses, providing critical insights for optimizing deep-sea aquaculture operations of L.crocea. These results offer valuable guidelines for the design and management of submersible cage systems. [ABSTRACT FROM AUTHOR]

Margalefidinium polykrikoides is a mixotrophic dinoflagellate harmful algal bloom (HAB) species that blooms annually in the lower Chesapeake Bay. M. polykrikoides undertakes a diel vertical migration (DVM) which may give it a competitive advantage over purely phototrophic organisms who cannot access deeper nutrient pools and allow it to form large toxic blooms. Laboratory-based estimates of M. polykrikoides’ DVM rates suggest that it is one of the fastest known dinoflagellate swimmers and understanding this behavior is likely important for modeling and predicting M. polykrikoides blooms. However, to date, no field-derived estimates of M. polykrikoides’ DVM rates have been made in the Chesapeake Bay. In this study, we conducted four targeted field experiments to investigate the DVM of M. polykrikoides in the Lafayette River, a sub-tributary of the Chesapeake Bay. Vertical profiles of chlorophyll a fluorescence collected at least every 2 h over diel periods were used to track the DVM of M. polykrikoides during blooms. The maximum observed DVM rate for M. polykrikoides was 2.5 m h−1, with mean DVM rates around 1.3 m h−1 for both ascents and descents. As in studies from other regions, our results show that M. polykrikoides’ ascent to/descent from the surface initiates before sunrise/sunset, suggesting phototaxis is not the primary trigger of their DVM. However, unlike in other studies where M. polykrikoides was observed to modulate its DVM to avoid excessively warm temperatures (≥30°C), we do not observe active thermotaxic avoidance, despite ambient temperatures exceeding their optimal threshold.

A unique acoustic call type was identified and attributed to Bryde's whales in the central North Pacific in 2015, but little is known about the distribution, calling behavior, or swimming behavior of Bryde's whales in the region. Acoustic detections attributed to Bryde's whales were used to localize and track individual whales on the U.S. Pacific Missile Range Facility (PMRF) in Kaua'i, Hawai'i. This study included 150 acoustically derived tracks from recordings spanning the years 2011-2022 with recording effort in nearly every month. Bryde's whale movement was examined relative to calendar year, day of year, hour of day, wind speed, and acoustic calling rate. Hidden Markov models were used to identify two kinematic states (slower, less directional movement and faster, more directional movement). The findings indicate that Bryde's whales were more likely to travel in a faster and more directional state during the daytime than at night and between May and August when compared to other times of year. The along-track acoustic cue rate was examined for 118 tracks, and the findings indicate a possible lengthening of the median inter-call interval over the duration of the study period. These results are an important first step in understanding more about behavior in Bryde's whales, a relatively understudied species. [ABSTRACT FROM AUTHOR]

The incorporation of microplastic particles (MPs) into the microbial food web and their impact on physiology of consuming organisms remains largely underexplored. The heterotrophic dinoflagellate Oxyrrhis marina is an excellent model for understanding these processes. In this study, flow cytometry was used to analyze the dynamics of consumption by this predator of its natural prey, the microalga Isochrysis galbana (ISO), and plastic microspheres (MS) of the same size. Furthermore, the effects of the diets containing these components on the swimming speed and movement patterns of Oxyrrhis marina cells were assessed. This was achieved using a computational method for analyzing video recordings of O. marina movement. It was observed from the first minutes of the experiment that the dinoflagellates actively consumed both types of prey, but by the end of the experiment, the number of MS in the medium decreased to a lesser extent, from 4.4 to 2.2 × 105 cells/mL, while Isochrysis galbana cells were almost completely grazed, with their abundance dropping by more than two orders of magnitude, from 4.9 × 105 cells/mL to 2.3 × 103 cells/mL. Such dynamics were associated with a compensatory increase in the number of microspheres in the medium due to their excretion and repeated phagocytosis by Oxyrrhis marina. Interestingly, the ingestion of plastic microspheres, which led to an increase in dinoflagellate cell size, did not significantly reduce their mobility or impair their locomotion. The 'unproductive' consumption of microplastics, which provided no nutritional benefit, resulted in a statistically significant reduction in dinoflagellate abundance compared to controls and the microalgae-fed experiment. This decline was attributed to the high energy expenditure of the population in constantly searching for, phagocytosing, and excreting microspheres. Contrary to expectations, the predators did not abandon this unproductive feeding strategy. Instead, their cell mobility increased over time, exacerbating the situation. These processes could have far-reaching negative implications for the entire food web. Specifically, microplastics 'packaged' by unicellular organisms could be transferred to higher trophic levels, potentially accumulating in mollusks, fish, and larger predators. [ABSTRACT FROM AUTHOR]

Estimating tailbeat frequency (TBF) is a crucial component of fish swimming kinematics and performance, particularly because it provides information about energetics and behavioral responses to environmental cues. The most commonly used technique for TBF estimation is based on accelerometers. This paper proposes a novel approach using bioimpedance technology. This is the first time bioimpedance has been measured in a freely moving animal. This was made possible by implanting a flexible electrode in the back muscle of seabasses and having them in a swimming tunnel. The experiment first demonstrates that it is possible to measure bioimpedance in an immersed fish despite the high conductivity of seawater. An agreement analysis was then performed to compare a video-based reference measurement of TBF with the newly proposed approach. Several bioimpedance settings, such as the configuration and the extracted electrical parameters, were considered. Data analysis highlights that a 4-point setup for modulus impedance measurement at frequencies over 10 kHz provides the best agreement (r > 0.98 and CCC > 0.97) with the video-based approach. These results attest to the significant benefits of integrating bioimpedance sensors in biologgers, especially considering the complementary parameters that can be extracted from bioimpedance measurements, such as length, weight, condition index, and fat content.

This study, conducted from February 7 to 25, 2023, at the Fishing Gear Materials laboratory within the Department of Fisheries Resource Utilisation, Faculty of Fisheries and Marine Sciences, Riau University, employed an experimental methodology conducted in a controlled laboratory setting. A total of 40 fish samples, specifically Kepar fish (Belontia hasselti) samples, with an average size of 11 cm and a standard deviation of ± 0,80768, were utilized. The B. hasselti, recognized for its substantial economic value as a freshwater species. This study aims to comprehensively evaluate swimming speed and endurance. The study revealed that sustained swimming speed of B. hasselti ranged from 1,94 to 2,21 Bl/sec, with a maximum sustained speed recorded at 2,21 Bl/sec. In addition, prolonged swimming speed varied from 1.94 Bl/sec to 6,98 Bl/sec, while burst swimming speed reached 6,20 Bl/sec. An in-depth analysis of the relationship between swimming speed and swimming endurance in B. hasselti indicated a negative correlation, supported by a coefficient of determination (R²) value of 0,5336. This observation substantiates that the swimming endurance diminishes as swimming speeds increase. Consequently, a higher swimming speed is inversely related to the swimming endurance of B. hasselti. [ABSTRACT FROM AUTHOR]

A unique acoustic call type was identified and attributed to Bryde’s whales in the central North Pacific in 2015, but little is known about the distribution, calling behavior, or swimming behavior of Bryde’s whales in the region. Acoustic detections attributed to Bryde’s whales were used to localize and track individual whales on the U.S. Pacific Missile Range Facility (PMRF) in Kaua‘i, Hawai‘i. This study included 150 acoustically derived tracks from recordings spanning the years 2011–2022 with recording effort in nearly every month. Bryde’s whale movement was examined relative to calendar year, day of year, hour of day, wind speed, and acoustic calling rate. Hidden Markov models were used to identify two kinematic states (slower, less directional movement and faster, more directional movement). The findings indicate that Bryde’s whales were more likely to travel in a faster and more directional state during the daytime than at night and between May and August when compared to other times of year. The along-track acoustic cue rate was examined for 118 tracks, and the findings indicate a possible lengthening of the median inter-call interval over the duration of the study period. These results are an important first step in understanding more about behavior in Bryde’s whales, a relatively under-studied species.

Abstract We evaluated the effect of probiotics on the growth and culture condition of rotifer in medium‐sized culture tanks. The influence of probiotics on the changes in swimming patterns, velocity and sinuosity indices of rotifer was also examined. The rotifers (Brachionus rotundiformis) were cultured for 14 days in nine polycarbonate tanks containing seawater which were divided into three groups: a control group (Chlorella product) and two treatment groups: Chlorella + Probiotic I and Chlorella + Probiotic II. The rotifer population and the water quality parameters were monitored daily. To evaluate the locomotory behaviour of the rotifer, a sub‐sample containing rotifers was obtained from each treatment and placed on a glass‐bottomed dish. A high‐speed camera mounted on a stereo microscope was used to record the rotifer movement. The footage was then analysed using motion analysis software to establish the swimming velocity, swimming pattern and sinuosity indices of the rotifers. Co‐feeding rotifer on microalgae and probiotics resulted in a higher rotifer growth rate (0.51 ± 0.03) and decreased concentration of unionized ammonia (0.14 ± 0.02 mg L−1). In addition, the probiotic‐fed rotifers had 1.59 times higher average swimming velocity (0.97 ± 0.11 mm s−1) and more straight swimming pattern compared to rotifers that fed on microalgae alone whose velocity was slow (0.61 ± 0.14 mm s−1) and more sinuous. From these data, we can postulate that probiotics have the potential to attenuate rotifer culture conditions by decreasing ammonia concentration as well as influence rotifer swimming behaviour which could affect rotifer reproduction and the quality of fish larvae in aquaculture systems.

This exercise aims to discover the Impact of Physical Education, Learning Sports, and Health on Body Mass Index and Physical Fitness Before and During the Covid 19 Pandemic at SMP Negeri 1 Losari Cirebon. Comparative research design with a research sample of 120 students. The sample in the study was taken by total sampling. The test instrument for measuring body mass index is measuring body weight with a kilogram scale and height with a meter in cm. Meanwhile, physical fitness is measured by the bleep test. The results of the study showed (1) There was an impact of learning sports and health physical education on body mass index before the covid 19 pandemic at SMP Negeri 1 Losari Cirebon (2) There was an impact of learning physical education sports and health on physical fitness before the covid 19 pandemic at SMP Negeri 1 Losari Cirebon.

We evaluated the effect of probiotics on the growth and culture condition of rotifer in medium‐sized culture tanks. The influence of probiotics on the changes in swimming patterns, velocity and sinuosity indices of rotifer was also examined. The rotifers (Brachionus rotundiformis) were cultured for 14 days in nine polycarbonate tanks containing seawater which were divided into three groups: a control group (Chlorella product) and two treatment groups: Chlorella + Probiotic I and Chlorella + Probiotic II. The rotifer population and the water quality parameters were monitored daily. To evaluate the locomotory behaviour of the rotifer, a sub‐sample containing rotifers was obtained from each treatment and placed on a glass‐bottomed dish. A high‐speed camera mounted on a stereo microscope was used to record the rotifer movement. The footage was then analysed using motion analysis software to establish the swimming velocity, swimming pattern and sinuosity indices of the rotifers. Co‐feeding rotifer on microalgae and probiotics resulted in a higher rotifer growth rate (0.51 ± 0.03) and decreased concentration of unionized ammonia (0.14 ± 0.02 mg L−1). In addition, the probiotic‐fed rotifers had 1.59 times higher average swimming velocity (0.97 ± 0.11 mm s−1) and more straight swimming pattern compared to rotifers that fed on microalgae alone whose velocity was slow (0.61 ± 0.14 mm s−1) and more sinuous. From these data, we can postulate that probiotics have the potential to attenuate rotifer culture conditions by decreasing ammonia concentration as well as influence rotifer swimming behaviour which could affect rotifer reproduction and the quality of fish larvae in aquaculture systems. [ABSTRACT FROM AUTHOR]

Eel fish (Anguilla bicolor) is a catadromous fish, the migration of eels from rivers (fresh water) to sea water can be disrupted if there are transverse structures such as dams. This is because the speed of water currents across buildings is higher, whereas eel fish are not active swimmers, so a fishway is needed to facilitate the eel fish migration process. Fishway construction requires several information such as swimming patterns, speed and swimming endurance. This research aims to describe the swimming patterns of elver stage eels, measure the swimming speed and swimming endurance of elver stage eels in different current conditions. Next, formulate the swimming performance of elver stage eels related to the need to design an appropriate fishway. This research was conducted at the Fish Behavior Laboratory, PSP-FPIK Department, IPB. The results of the research show that the swimming pattern of the elver stage eel is the Anguilliform type, the sustained speed of the eel fish is ≤ 0.91 TL/second, the prolonged speed of the eel fish is 1.57-1.82 TL/second, and the burst swimming speed the speed of eel fish is ≤2.7 TL/second. Based on this data, the fishway design that suits the prolonged swimming speed of eel fish is the fish lock type which can be made with a slope of 20º accompanied by water discharge range 59 ml/secand speed current 30 cm/sec. [ABSTRACT FROM AUTHOR]

The capacity to compensate for environmental change determines population persistence and biogeography. In ectothermic organisms, performance at different temperatures can be strongly affected by temperatures experienced during early development. Such developmental plasticity is mediated through epigenetic mechanisms that induce phenotypic changes within the animal's lifetime. However, epigenetic modifiers themselves are encoded by DNA so that developmental plasticity could itself be contingent on genetic diversity. In this study, we test the hypothesis that the capacity for developmental plasticity depends on a species' among-individual genetic diversity. To test this, we exploited a unique species complex that contains both the clonal, genetically identical Amazon molly (Poecilia formosa), and the sexual, genetically diverse Atlantic molly (Poecilia mexicana). We predicted that the greater among-individual genetic diversity in the Atlantic molly may increase their capacity for developmental plasticity. We raised both clonal and sexual mollies at either warm (28°C) or cool (22°C) temperatures and then measured locomotor capacity (critical sustained swimming performance) and unforced movement in an open field across a temperature gradient that simulated environmental conditions often experienced by these species in the wild. In the clonal Amazon molly, differences in the developmental environment led to a shift in the thermal performance curve of unforced movement patterns, but much less so in maximal locomotor capacity. In contrast, the sexual Atlantic mollies exhibited the opposite pattern: developmental plasticity was present in maximal locomotor capacity, but not in unforced movement. Thus our data show that developmental plasticity in clones and their sexual, genetically more diverse sister species is trait dependent. This points toward mechanistic differences in how genetic diversity mediates plastic responses exhibited in different traits.

Trait-based ecology is a rapidly growing approach for developing insights and predictions for data-poor species. Caudal tail fin shape has the potential to reveal much about the energetics, activity and ecology of fishes and can be rapidly measured from field guides, which is particularly helpful for data-sparse species. One outstanding question is whether swimming speed in sharks is related to two morphological traits: caudal fin aspect ratio (CFAR, height2/tail area) and caudal lobe asymmetry ratio (CLAR). We derived both metrics from the species drawings in Sharks of the world (Ebert et al. 2013 Sharks of the world: a fully illustrated guide) and related fin shape to two published datasets of (1) instantaneous swimming speeds (Jacoby et al. 2015 Biol. Lett. 11, 20150781 (doi:10.1098/rsbl.2015.0781)) and (2) cruising speeds (Harding et al. 2021 Funct. Ecol. 35, 1951–1959 (doi:10.1111/1365-2435.13869)) for 28 total unique shark species. Both estimates of swimming speed were positively related to CFAR (and weakly negatively to CLAR). Hence, shark species with larger CFAR and more symmetric tails (low CLAR) tended to be faster-moving and have higher average speeds. This relationship demonstrates the opportunity to use tail shape as an easily measured trait to index shark swimming speed to broader trait-based analyses of ecological function and extinction risk.

Biological evidence demonstrates that fish can tune their body stiffness to improve thrust and efficiency during swimming locomotion. However, the stiffness-tuning strategies that maximize swimming speed or efficiency are still unclear. In the present study, a musculo-skeletal model of anguilliform fish is developed to study the properties of variable stiffness, in which the planar serial-parallel mechanism is used to model the body structure. The calcium ion model is adopted to simulate muscular activities and generate muscle force. Further, the relations among the forward speed, the swimming efficiency, and Young's modulus of the fish body are investigated. The results show that for certain body stiffness, the swimming speed and efficiency are increased with the tail-beat frequency until reaching the maximum value and then decreased. The peak speed and efficiency are also increased with the amplitude of muscle actuation. Anguilliform fish tend to vary their body stiffness to improve the swimming speed and efficiency at a high tail-beat frequency or small amplitude of muscle actuation. Furthermore, the midline motions of anguilliform fish are analyzed by the complex orthogonal decomposition (COD) method, and the discussions of fish motions associated with the variable body stiffness and the tail-beat frequency are also presented. Overall, the optimal swimming performance of anguilliform fish benefits from the matching relationships among the muscle actuation, the body stiffness, and the tail-beat frequency. [ABSTRACT FROM AUTHOR]

Transmission is a key process affecting the stability and dynamics of host–parasite systems and thus driving infections. Efficient management of potentially harmful parasites, such as monogeneans, is essential in aquaculture and requires an understanding of their transmission in changing environments. This study analysed the effect of larval age and water temperature on the swimming behaviour and transmission of Sparicotyle chrysophrii , a pathogenic monogenean commonly found in gilthead seabream, Sparus aurata , from the western Mediterranean Sea. Three experiments were designed to assess the effects of both factors on (1) irregular (i.e. forward, irregular, conspicuous and fast movements) and vertical swimming periods, (2) swimming speed in a thin water layer and (3) upward and downward swimming behaviour. Increasing age reduced the vertical swimming speed and the number of larvae swimming vertically, thus increasing the number of larvae at the bottom of the test tube, when oncomiracidia were added at the top. Increasing water temperature also minimized the number of vertical movements per larva as well as the vertical swimming speed, while shortening the duration of irregular and vertical swimming patterns. The loss of vertical swimming performance of S. chrysophrii with increasing age suggests that active dispersal processes can be compromised after 24 h, especially at higher water temperatures where the infection window is even shorter. Therefore, passive dispersion of the infective stages is likely to contribute substantially to parasite transmission, especially when hosts are not nearby. • Temperature and age affect swimming behaviour of Sparicotyle chrysophrii. • Temperature increase reduces swimming periods, speed and vertically swimming larvae. • Increasing age compromises the vertical swimming performance of oncomiracidia. • Active transmission is constrained after 24 h posthatching and at high temperatures. • The 18–22 °C range improves swimming performance, which is crucial in host finding. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Hydrobiology is the property of Editorial Department of Journal of Hydrobiology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We examined the blood lactate response, in terms of the maximal post-exercise concentration (Lamax), time to reach Lamax, and maximal lactate accumulation rate (VLamax), to swimming sprints of 25, 35, and 50 m. A total of 14 highly trained and elite swimmers (8 male and 6 female), aged 14–32, completed the 3 sprints in their specialization stroke with 30 min of passive rest in between. The blood lactate was measured right before and continually (every minute) after each sprint to detect the Lamax. The VLamax, a potential index of anaerobic lactic power, was calculated. The blood lactate concentration, swimming speed, and VLamax differed between the sprints (p < 0.001). The Lamax was highest after 50 m (13.8 ± 2.6 mmol·L–1, mean ± SD throughout), while the swimming speed and VLamax were highest at 25 m (2.16 ± 0.25 m·s–1 and 0.75 ± 0.18 mmol·L–1·s–1). The lactate peaked approximately 2 min after all the sprints. The VLamax in each sprint correlated positively with the speed and with each other. In conclusion, the correlation of the swimming speed with the VLamax suggests that the VLamax is an index of anaerobic lactic power and that it is possible to improve performance by augmenting the VLamax through appropriate training. To accurately measure the Lamax and, hence, the VLamax, we recommend starting blood sampling one minute after exercise. [ABSTRACT FROM AUTHOR]

Behavioral responses to sonar have been observed in a number of baleen whales, including minke whales (Balaenoptera acutorostrata). Previous studies used acoustic minke whale boing detections to localize and track individual whales on the U.S. Pacific Missile Range Facility (PMRF) in Kaua ‘i, Hawai‘i before, during, and after Navy training activities. These analyses showed significant changes in central North Pacific minke whale distribution and swimming behavior during Navy sonar events. For the purposes of contextualizing changes in animal movement relative to Navy sonar, we expanded on this research to examine the natural variation in minke whale movement when Navy sonar was not present. This study included 2,245 acoustically derived minke whale tracks spanning the years 2012–2017 over all months that minke whales were detected (October–May). Minke whale movement was examined relative to calling season, day of the year, hour of day, wind speed, calling state (nominal or rapid), and distance to the nearest calling conspecific. Hidden Markov models were used to identify two kinematic states (slower, less directional movement and faster, more directional movement). The findings indicate that minke whales were more likely to travel in a faster and more directional state when they were calling rapidly, when other vocalizing minke whales were nearby, during certain times of the day and calling seasons, and in windier conditions, but these changes in movement were less intense than the changes observed during exposure to Navy sonar, when swim speeds were the fastest. These results start to put behavioral responses to Navy sonar into an environmental context to understand the severity of responses relative to natural changes in behavior.

Underwater robotics is rapidly evolving due to the increasing demand for marine resource exploitation. Compared with rigid robots propelled by propellers, bionic robots are stealthier and more maneuverable, such as autonomous underwater vehicles (AUVs) and remotely operated vehicles (ROVs), making them widely used underwater. In order to study the motion state of the umbrella jellyfish bionic robot, the displacement of the jellyfish robot along the same direction and the surrounding fluid pressure distribution caused by the jellyfish motion under different experimental conditions are discussed in this paper. The effect of different environmental factors on driving the jellyfish robot is determined by comparing the displacements at different observation points. The results of the study show that the lower the frequency and the longer the motion period, the greater the displacement produced by the robot within the same motion period. Frequency has a significant effect on the motion state of the jellyfish robot. While the change of amplitude also affects the motion state of the jellyfish robot, the displacement of the relaxation phase of the jellyfish robot is much smaller than that of the contraction phase with a small amplitude. It can be concluded that the effect of frequency on robot displacement is greater than the effect of amplitude on robot displacement. This study qualitatively discusses the changes of the motion state of the bionic jellyfish robot in still water under the excitation of different frequencies and amplitudes, and the results can provide corresponding reference for the future application of the bionic jellyfish robot, such as resource exploration, underwater exploration, and complex environment exploration. [ABSTRACT FROM AUTHOR]

Submarine power cables carry electricity over long distances. Their geographic distribution, number, and areal coverage are increasing rapidly with the development of, for example, offshore wind facilities. The flow of current passing through these cables creates a magnetic field (MF) that can potentially affect marine organisms, particularly those that are magnetosensitive. The lumpfish (Cyclopterus lumpus) is a migratory species that is widely distributed in the North Atlantic Ocean and Barents Sea. It migrates between coastal spawning grounds and pelagic offshore feeding areas. We tested whether lumpfish respond to MFs of the same intensity as those emitted by high voltage direct current (HVDC) submarine power cables. Laboratory experiments were conducted by placing juvenile lumpfish in an artificial MF gradient generated by a Helmholtz coil system. The intensity of the artificial MF used (230 µT) corresponded to the field at 1 m from a high-power submarine cable. The fish were filmed for 30 min with the coil either on or off. Swimming speeds, and presence in the different parts of a raceway, were extracted from the videos and analyzed. Juvenile lumpfish activity, defined as the time that the fish spent swimming relative to stationary pauses (attached to the substrate), and the distance travelled, were unaffected by exposure to the artificial MF. The swimming speed of juvenile lumpfish was reduced (by 16%) when the coil was on indicating that the fish could either sense the MF or the induced electric field created by the movement of the fish through the magnetic field. However, it seems unlikely that a 16% decrease in swimming speed occurring within 1 m of HVDC cables would significantly affect Atlantic lumpfish migration or homing. [ABSTRACT FROM AUTHOR]

Submarine power cables carry electricity over long distances. Their geographic distribution, number, and areal coverage are increasing rapidly with the development of, for example, offshore wind facilities. The flow of current passing through these cables creates a magnetic field (MF) that can potentially affect marine organisms, particularly those that are magnetosensitive. The lumpfish (Cyclopterus lumpus) is a migratory species that is widely distributed in the North Atlantic Ocean and Barents Sea. It migrates between coastal spawning grounds and pelagic offshore feeding areas. We tested whether lumpfish respond to MFs of the same intensity as those emitted by high voltage direct current (HVDC) submarine power cables. Laboratory experiments were conducted by placing juvenile lumpfish in an artificial MF gradient generated by a Helmholtz coil system. The intensity of the artificial MF used (230 µT) corresponded to the field at 1 m from a high-power submarine cable. The fish were filmed for 30 min with the coil either on or off. Swimming speeds, and presence in the different parts of a raceway, were extracted from the videos and analyzed. Juvenile lumpfish activity, defined as the time that the fish spent swimming relative to stationary pauses (attached to the substrate), and the distance travelled, were unaffected by exposure to the artificial MF. The swimming speed of juvenile lumpfish was reduced (by 16%) when the coil was on indicating that the fish could either sense the MF or the induced electric field created by the movement of the fish through the magnetic field. However, it seems unlikely that a 16% decrease in swimming speed occurring within 1 m of HVDC cables would significantly affect Atlantic lumpfish migration or homing.

Respiratory rate (mean number of breaths per minute) and respiratory interval (mean time between breaths) can offer insight into a diving mammal's activity state, metabolic rate, behavior, and synchronization due to social cohesion. Also, respiratory rate can reflect an individual animal's health and has the potential to be an informative remotely assessed health metric for monitoring individual animal health in endangered whale species and populations such as southern resident killer whales (Orcinus orca). Using data collected from noninvasive, land-based theodolite tracking, we analyzed swimming speed and surfacing intervals (i.e., mean dive time or mean time between breaths) from 20,613 surfacings of 98 individuals from two populations of the fish-eating, resident killer whale ecotype, namely, one growing (northern resident) and one declining and endangered (southern resident) population. Focal animal sampling was used to measure behavior of individuals of known age and sex in various activity states. Our objective was to evaluate variability and generate normal ranges for respiratory intervals and swimming speeds for killer whales of the Northeast Pacific Ocean resident, fish-eating ecotype to identify baseline respiratory intervals. We found that median respiratory intervals for fish-eating killer whales were between 26 and 29 s for all activity states and that swimming speeds varied by activity state. Median swimming speeds were similar for foraging and traveling (1.6 and 1.7 m/s, respectively), but were significantly slower during resting (1.1 m/s) and social activity (1.3 m/s) states. Three southern resident killer whales in poor body condition (had body condition scores in the lowest 20th percentile of the population) swam at reduced speeds and had shorter median respiratory intervals than outwardly healthy whales of similar age and sex. Respiratory rates, respiratory intervals, and swimming speeds are valuable remotely sensed metrics of health for free-swimming killer whales, especially when combined with other metrics as is the standard in veterinary examinations., (© Wildlife Disease Association 2024.)

In this work, we examined the effects of rapid changes in salinity on the availability (mobility and swimming) of the prey rotifer Proales similis. Rotifers were transferred as follows: 5 to 15, 25 and 35 (T1); 15 to 5, 25 and 35 (T2); 25 to 5, 15 and 35 (T3) and 35 to 5, 15 and 25 ppt (T4) during 1–240 min. Results showed that in T2 and T3, the percentage of mobile rotifers in the water column recovered up to 100% after 15 min. At T1 and T4, mobility regained slower at 35 and 5 ppt respectively. All individuals transferred at 15 and 25 ppt maintained their mobility above 93% after 15 min. In general, swimming speed ranged from 0.37 to 0.65 mm s−1 and was higher at 15 ppt and lower at 35 ppt. In all salinities, swimming increased with time and recovered better in T2 and T3. These data suggest that P. similis can acclimate to a wide range of salinity gradients in the short term (1–240 min). According to the literature and our results, P. similis has a greater tolerance to sudden salinity changes than brachionid rotifers used traditionally in fish larviculture. [ABSTRACT FROM AUTHOR]

Organismal metabolic rates (MRs) are the basis of energy and nutrient fluxes through ecosystems. In the marine realm, fishes are some of the most prominent consumers. However, their metabolic demand in the wild (field MR [FMR]) is poorly documented, because it is challenging to measure directly. Here, we introduce a novel approach to estimating the component of FMR associated with voluntary activity (i.e., the field active MR [AMRfield]). Our approach combines laboratory‐based respirometry, swimming speeds, and field‐based stereo‐video systems to estimate the activity of individuals. We exemplify our approach by focusing on six coral reef fish species, for which we quantified standard MR and maximum MR (SMR and MMR, respectively) in the laboratory, and body sizes and swimming speeds in the field. Based on the relationships between MR, body size, and swimming speeds, we estimate that the activity scope (i.e., the ratio between AMRfield and SMR) varies from 1.2 to 3.2 across species and body sizes. Furthermore, we illustrate that the scaling exponent for AMRfield varies across species and can substantially exceed the widely assumed value of 0.75 for SMR. Finally, by scaling organismal AMRfield estimates to the assemblage level, we show the potential effect of this variability on community metabolic demand. Our approach may improve our ability to estimate elemental fluxes mediated by a critically important group of aquatic animals through a non‐destructive, widely applicable technique. [ABSTRACT FROM AUTHOR]

This study is intended to determine sex and age differences in young Canadian freestyle swimmers aged from ≤10 to 18, for all 6 distances from 50m to 1500m in both short and long course indoor pools. The data set used in the studies is publicly available and categorized into sex/age/course/distance groups during seasons from 2008 to 2019. The sex differences in swimming speed were determined using independent Ztests (two-sided, unequal SD). The age differences in swimming speed over all ages were analysed using classic one-way ANOVA with subsequent pairwise Tukey-HSD post-hoc tests and Welch's ANOVA followed by pairwise Games-Howell post-hoc tests. They were then determined using paired two-sample t-tests (twosided). Young male swimmers outperformed young female swimmers in most groups. Groups with similar performances or no significant differences were in younger age groups (10-year and 11-year). Sex differences increased as age increased, ranging from -0.96% to 13.54%. Sex differences in shorter distances and short course were smaller than in longer distances and long course for ≤12 years and became greater than in longer distances at ≥13 years. Age speed differences decreased as age increased until 17-18-years old, ranging from 12.79% to -0.37%. The performance of female swimmers became stable earlier than that of male swimmers. The age-to-age speed differences of male swimmers were greater than those of female swimmers. These gaps increased from 10-11-year to 13-14-year groups and decreased after that. Age differences in shorter distances and short course were greater than in longer distances and long course. Further studies are required to confirm and extend this research to swimmers at other age groups, in other strokes, and from other countries. [ABSTRACT FROM AUTHOR]

Skeletal abnormalities in farmed fish are one of the main problems that negatively affect the production enterprises in terms of economic, biological and animal health. Fish with skeletal deformities in hatcheries are considered as non-economic individuals and are therefore detected and removed manually from the production tanks, which is a time consuming and laborious work for the facilities. Since the formation of abnormalities in the skeletal structure of the fish during the early growth period cause reduced swimming ability or speed that prevent fish to compete during feeding. Further, since deformed fish has no market value, even the share of a small amount of feed among deformed fish will reduce the feed conversion for the market targeted individuals within the culture tank that in terms may increase the production cost per fish. Therefore, in culture conditions it is important to remove the deformed fish from the tank environment by quickly determining those fellows at the early stage of growth. The present study evaluates the effects of water velocity on swimming behavior of juvenile seabass (Dicentrarchus labrax) and provides a solution for a rapid identification -and mechanical removal of deformed fish from the culture environment by using swimming speed slowdown -and behavioral differences as an indicator of deformation.

Successful artificial insemination relies on the use of high quality spermatozoa. One measure of sperm quality is swimming force. Increased swimming force has been correlated with higher sperm swimming speeds and improved reproductive success. It is hypothesized that by increasing sperm swimming speed, one can increase swimming force. Previous studies have shown that red light irradiation causes an increase in sperm swimming speed. In the current study, 633nm red light irradiation is shown to increase mean squared displacement in trapped sperm. The methodology allows for comparison of relative swimming forces between irradiated and non-irradiated samples.

Red light has been shown to increase sperm swimming speeds, but there is little characterization of its effect on DNA or swimming force. In this study 633nm laser light irradiation did not induce significant levels of oxidative DNA damage.

Biological evidence demonstrates that fish can tune their body stiffness to improve thrust and efficiency during swimming locomotion. However, the stiffness-tuning strategies that maximize swimming speed or efficiency are still unclear. In the present study, a musculo-skeletal model of anguilliform fish is developed to study the properties of variable stiffness, in which the planar serial-parallel mechanism is used to model the body structure. The calcium ion model is adopted to simulate muscular activities and generate muscle force. Further, the relations among the forward speed, the swimming efficiency, and Young’s modulus of the fish body are investigated. The results show that for certain body stiffness, the swimming speed and efficiency are increased with the tail-beat frequency until reaching the maximum value and then decreased. The peak speed and efficiency are also increased with the amplitude of muscle actuation. Anguilliform fish tend to vary their body stiffness to improve the swimming speed and efficiency at a high tail-beat frequency or small amplitude of muscle actuation. Furthermore, the midline motions of anguilliform fish are analyzed by the complex orthogonal decomposition (COD) method, and the discussions of fish motions associated with the variable body stiffness and the tail-beat frequency are also presented. Overall, the optimal swimming performance of anguilliform fish benefits from the matching relationships among the muscle actuation, the body stiffness, and the tail-beat frequency.

We examined the blood lactate response, in terms of the maximal post-exercise concentration (Lamax), time to reach Lamax, and maximal lactate accumulation rate (VLamax), to swimming sprints of 25, 35, and 50 m. A total of 14 highly trained and elite swimmers (8 male and 6 female), aged 14–32, completed the 3 sprints in their specialization stroke with 30 min of passive rest in between. The blood lactate was measured right before and continually (every minute) after each sprint to detect the Lamax. The VLamax, a potential index of anaerobic lactic power, was calculated. The blood lactate concentration, swimming speed, and VLamax differed between the sprints (p < 0.001). The Lamax was highest after 50 m (13.8 ± 2.6 mmol·L–1, mean ± SD throughout), while the swimming speed and VLamax were highest at 25 m (2.16 ± 0.25 m·s–1 and 0.75 ± 0.18 mmol·L–1·s–1). The lactate peaked approximately 2 min after all the sprints. The VLamax in each sprint correlated positively with the speed and with each other. In conclusion, the correlation of the swimming speed with the VLamax suggests that the VLamax is an index of anaerobic lactic power and that it is possible to improve performance by augmenting the VLamax through appropriate training. To accurately measure the Lamax and, hence, the VLamax, we recommend starting blood sampling one minute after exercise.

We know that natural selection brought marine mammals to favor lift-based propulsion rather than drag-based propulsion. Curiously, none of these techniques is favored in swimming competitions by professional swimmers. Is it possible to invent new swimming styles under the pressure of selection as marine mammals did? We wondered if 61 athletes would be able to replicate the techniques used by the species most adapted to the aquatic environment, without being forced to it and with the sole intention of swimming faster. We imagined a system of shoulder-to-shoulder duel in ascent/descent. There were two swimmers in each lane. In each lane, a weighted object was placed at the bottom of the water, 15 meters from the pool deck. The first to grab the object in his lane won the duel and moved up one lane for the next trial. After eight duels, the best swimmers were in lane eight, the slowest in lane one. Six techniques have emerged from the 244 duels in forced immersion (488 dives followed by 15-meter races): (i) moving with the legs only, arms along the body (beats), (ii) total breaststroke, (iii) hybrid breaststroke (simultaneous and symmetrical arm movements, synchronous to the leg beats), (iv) gallop: undulation of the body with leg beats, (v) undulation of the whole body, (vi) the snake technique: characterized by a leg beat synchronous to an oscillation of the upper part of the body, with the arms along the trunk. Although the matching is not perfect, the processes used by swimmers fit the models presented to describe the odyssey of mammals that have been going back to the water for 60 million years: the fastest swimming techniques are the ones that best mimic the marine mammals that are best adapted to speed ("pectoral oscillation" like sea lions; "caudal oscillations" like whales). The later favor lift forces over propulsive drag forces (drag forces which can be observed in dogs, rats and other swimmers in Johnny Weissmuller's freestyle that use "quadrupedal paddling" and "alternative pectoral paddling"). The competition swimmers observed were able to experimentally reproduce the choices of natural selection. But today, the fastest ways of moving in the water are not found in the Swimming Federation training sessions. [ABSTRACT FROM AUTHOR]

High-resolution multibeam sonar allows estimating movements of pelagic fish schools at short range. Taking advantage of this methodology, we calculated a Straightness Index (SI) to quantify the proportion of schools migrating actively from those residents in lagoon channels. This information enhances our knowledge of both fish school displacements and migration processes, which are essential to improve our understanding of ecosystem functioning. Most fish schools (65%) exhibited a SI value demonstrating oriented swimming behavior through the channels displayed by schools reaching the sea during fall migration. This trend appears as an intrinsic property of school movements, allowing monitoring of the school migration process in a channel to provide information for manager vs. fishing regulation measures or lagoon planning. The result strengthens the 'multi-transit' hypothesis, as 35% of schools show sinuous trajectories representative of schools staying in the channel or displaying high exploratory behaviors. Lastly, the fish school Exploration Swimming Speed (ESS) was tested as a fishery-independent sampling method to evaluate the proportion of different fish species monitored using hydroacoustics. This approach demonstrates the interest in using swimming behavioral characteristics of fish schools for ecological and management purposes. [ABSTRACT FROM AUTHOR]

Rotations of the flagella control the movement of a peritrichous (multiflagellar) bacterium in fluids, the run and tumble events being caused through modulations in the flagella's collective rotation speed and pattern. Observing such modulations is a challenge in free swimming bacteria. In this work, we present a setup to measure the collective flagellar rotational features of an optically confined Bacillus subtilis bacterium. We adopt a Continuous Wavelet Technique (CWT) while monitoring the rotational patterns in frequency and time, thus achieving optimal resolution in both the domains. This enables in marking the events wherein subtle changes in the flagellar rotational pattern occur. These studies unravel a fact, hitherto unknown, that variations in swimming speed that are seen in pure run sequences are also caused by modulations in the rotating flagella. Further, we have monitored the flagellar rotation for durations over a minute and observe a gradual slowing down of the rotation before ceasing completely due to the trapping laser induced photodamage. We have observed a significant alteration in the rate of rotational fall off in real time with changes in pH or the nutrient concentration in the fluid. This work serves to demonstrate the advantage of optical confinement of a bacterium in its pristine form for carrying out such studies and can serve as a marker for work that assesses membrane photodamage in active matter. Details on the role of flagella in propulsion and on other factors influencing the rotations, can be of significance in the design of artificial microswimmers. [ABSTRACT FROM AUTHOR]

Simple Summary: Most physiological processes are subject to biological circadian rhythms maintained by a complex cascade of biochemical events. The circadian rhythmicity of behavior allows organisms to use energy and resources optimally under changing environmental conditions. To that end, endogenous circadian rhythms are synchronized with external pacemakers (zeitgebers), especially daily changes in illumination. In the 1960s, it was assumed that, in addition to this primary photic cue, animals can use diurnal geomagnetic variation as a secondary zeitgeber. Earlier research found that slow magnetic fluctuations can affect some behavioral endpoints of circadian rhythms by modulating an organism's physiological state. However, no direct experiments to test such an entrainment of biological clocks by artificial magnetic fields were performed due to the technical difficulty of eliminating natural geomagnetic variation. For the first time, we carried out such tests in a fully controlled magnetic environment using zebrafish as a research model. The experimental treatments included various light/dark cycles and continuous illumination coupled with pre-recorded natural geomagnetic variations. The obtained results indicate that slow magnetic fluctuations can entrain endogenous rhythmical activity in vertebrates. Probably, cryptochromes play a key role in this process. This research provides promising opportunities for the magnetic control of circadian processes, e.g., correcting circadian dysfunctions. In the 1960s, it was hypothesized that slow magnetic fluctuations could be a secondary zeitgeber for biological circadian rhythms. However, no comprehensive experimental research has been carried out to test the entrainment of free-running circadian rhythms by this zeitgeber. We studied the circadian patterns of the locomotor activity of zebrafish (Danio rerio) under different combinations of light regimes and slow magnetic fluctuations, based on a record of natural geomagnetic variation. A rapid synchronization of activity rhythms to an unusual 24:12 light/dark cycle was found under magnetic fluctuations with a period of 36 h. Under constant illumination, significant locomotor activity rhythms with 26.17 h and 33.07 h periods were registered in zebrafish exposed to magnetic fluctuations of 26.8 h and 33.76 h, respectively. The results reveal the potential of magnetic fluctuations for entrainment of circadian rhythms in zebrafish and genuine prospects to manipulate circadian oscillators via magnetic fields. The putative mechanisms responsible for the entrainment are discussed, including the possible role of cryptochromes. [ABSTRACT FROM AUTHOR]

Abstract Background Data storage tags (DSTs) record and store information about animals and their environment, and can provide important data relevant to fish culture, ecology and conservation. A DST has recently been developed that records heart rate (f H), electrocardiograms (ECGs), tri-axial acceleration and temperature. However, at the time of this study, no research using these tags had been performed on fish or determined the quality of the data collected. Thus, our research asked: do these DSTs provide reliable and meaningful data? To examine this question, Atlantic salmon (1.4 ± 0.7 kg) were implanted with DSTs, then swam at increasing speeds in a swim tunnel after 1 week of recovery. Further, in two separate experiments, salmon (2.4 ± 0.1 kg) were implanted with DSTs and held in a large tank with conspecifics for 1 week at 11 °C or 6 weeks at 8–12 °C. Results External acceleration (EA) and variation in EA (VAR) increased exponentially with swimming speed and tail beat frequency. The quality index (QI) assigned to ECG recordings (where QI0 means very good quality, and QI1, QI2 and QI3 are of reduced quality) did not change significantly with increasing swimming speed (QI0 ~ 60–80%). However, we found that the accuracy of the tag algorithm in estimating f H from ECGs was reduced when QI>0. Diurnal patterns of f H and EA were evident from the time the salmon were placed in the tank. Heart rate appeared to stabilize by ~ 4 days post-surgery in the first experiment, but extended holding showed that f H declined for 2–3 weeks. During extended holding, the tag had difficulty recording low f H values 0 can be manually calculated. Conclusions With these DSTs, parameters of acceleration can be used to monitor the activity of free-swimming salmon. Further, changes in f H and heart rate variability (HRV) due to diurnal rhythms, and in response to temperature, activity and stressors, can be recorded.

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Many man-made chemicals that are released into water bodies in agricultural landscapes have been identified as endocrine disruptors and can cause serious impacts on the growth and survival of aquatic species living in these environments. However, very little attention has been paid to their toxicological effects in cultured non-fish species, such as aquatic turtles. We exposed hatchlings of the Chinese soft-shelled turtle (Pelodiscus sinensis) to different concentrations of vinclozolin (0, 5, 50 and 500 μg/L) for 60 days to assess physiological and metabolic impacts of this fungicide. Despite no death occurrence, hatchling turtles exposed to the highest concentration of vinclozolin consumed less food, grew more slowly (resulting in smaller body size after exposure) and performed more poorly in behavioral swimming tests than controls and turtles exposed to lower concentrations. Hepatic metabolite profiles acquired via liquid chromatography-mass spectrometry (LC-MS) revealed multiple metabolic perturbations related to amino acid, lipid, and fatty acid metabolism in animals exposed to environmentally relevant concentrations. Specifically, many critical metabolites involved in energy-related metabolic pathways (such as some intermediates in the tricarboxylic acid cycle, lactate, and some amino acids) were present in livers of hatchling turtles exposed vinclozolin, though at lower concentrations, reflecting energy metabolism dysregulation induced by exposure to this fungicide. Overall, our results suggest that the changes in growth and behavioral performances caused by chronic vinclozolin exposure may be associated with internal physiological and metabolic disorders mediated at the biochemical level.

The capacity to compensate for environmental change determines population persistence and biogeography. In ectothermic organisms, performance at different temperatures can be strongly affected by temperatures experienced during early development. Such developmental plasticity is mediated through epigenetic mechanisms that induce phenotypic changes within the animal's lifetime. However, epigenetic modifiers themselves are encoded by DNA so that developmental plasticity could itself be contingent on genetic diversity. In this study, we test the hypothesis that the capacity for developmental plasticity depends on a species' among-individual genetic diversity. To test this, we exploited a unique species complex that contains both the clonal, genetically identical Amazon molly (Poecilia formosa), and the sexual, genetically diverse Atlantic molly (Poecilia mexicana). We predicted that the greater among-individual genetic diversity in the Atlantic molly may increase their capacity for developmental plasticity. We raised both clonal and sexual mollies at either warm (28°C) or cool (22°C) temperatures and then measured locomotor capacity (critical sustained swimming performance) and unforced movement in an open field across a temperature gradient that simulated environmental conditions often experienced by these species in the wild. In the clonal Amazon molly, differences in the developmental environment led to a shift in the thermal performance curve of unforced movement patterns, but much less so in maximal locomotor capacity. In contrast, the sexual Atlantic mollies exhibited the opposite pattern: developmental plasticity was present in maximal locomotor capacity, but not in unforced movement. Thus our data show that developmental plasticity in clones and their sexual, genetically more diverse sister species is trait dependent. This points toward mechanistic differences in how genetic diversity mediates plastic responses exhibited in different traits. [ABSTRACT FROM AUTHOR]