Maximum Swimming Speed Research Articles

Exercise training does not affect heat tolerance in Chinook salmon (Oncorhynchus tshawytscha)

The progression of climate warming will expose ectotherms to transient heatwave events and temperatures above their tolerance range at increased frequencies. It is therefore pivotal that we understand species' physiological limits and the capacity for various controls to plastically alter these thresholds. Exercise training could have beneficial impacts on organismal heat tolerance through improvements in cardio-respiratory capacity, but this remains unexplored. Using juvenile Chinook salmon (Oncorhynchus tshawytscha), we tested the hypothesis that exercise training improves heat tolerance through enhancements in oxygen-carrying capacity. Fish were trained once daily at 60% of their maximum sustainable swim speed, UCRIT, for 60 min. Tolerance to acute warming was assessed following three weeks of exercise training, measured as the critical thermal maximum (CTMAX). CTMAX measurements were coupled with examinations of the oxygen carrying capacity (haematocrit, haemoglobin concentration, relative ventricle size, and relative splenic mass) as critical components of the oxygen transport cascade in fish. Contrary to our hypothesis, we found that exercise training did not raise the CTMAX of juvenile Chinook salmon with a mean CTMAX increase of just 0.35 °C compared to unexercised control fish. Training also failed to improve the oxygen carrying capacity of fish. Exercise training remains a novel strategy against acute warming that requires substantial fine-tuning before it can be applied to the management of commercial and wild fishes.

Sprint Performance in Arms-Only Front Crawl Swimming Is Strongly Associated With the Power-To-Drag Ratio.

To date, optimal propulsion in swimming has been studied predominantly using physical or computational models of the arm and seldom during real-life swimming. In the present study we examined the contributions of selected power, technique and anthropometric measures on sprint performance during arms-only front crawl swimming. To this end, 25 male adult competitive swimmers, equipped with markers on their arms and hands, performed four 25-m sprint trials, which were recorded on video. For the fastest trial of each swimmer, we determined the average swim speed as well as two technique variables: the average stroke width and average horizontal acceleration. Each participant also swam 10–12 trials over a custom-made system for measuring active drag, the MAD system. Since the propelling efficiency is 100% while swimming over the MAD system, the power output of the swimmer is fully used to overcome the drag acting on the body. The resulting speed thus represents the ratio between power output and drag. We included this power-to-drag ratio, the power output and the drag coefficient of the fastest trial on the MAD system in the analysis. Finally, the body height and hand surface area of each swimmer were determined as anthropometric variables. A model selection procedure was conducted to predict the swim speed from the two technique variables, three power variables and the two anthropometric variables. The ratio between power output and the drag was the only significant predictor of the maximal swimming speed (v = 0.86·power/drag). The variations in this ratio explained 65% of the variance in swimming performance. This indicates that sprint performance in arms-only front crawl swimming is strongly associated with the power-to-drag ratio and not with the isolated power variables and the anthropometric and technique variables selected in the present study.

Metabolic and Transcriptional Adaptations Improve Physical Performance of Zebrafish.

Obesity is a worldwide public health problem with increasing prevalence and affects 80% of diabetes mellitus type 2 cases. Zebrafish (Danio rerio) is an established model organism for studying obesity and diabetes including diabetic microvascular complications. We aimed to determine whether physical activity is an appropriate tool to examine training effects in zebrafish and to analyse metabolic and transcriptional processes in trained zebrafish. A 2- and 8-week experimental training phase protocol with adult zebrafish in a swim tunnel system was established. We examined zebrafish basic characteristics before and after training such as body weight, body length and maximum speed and considered overfeeding as an additional parameter in the 8-weeks training protocol. Ultimately, the effects of training and overfeeding on blood glucose, muscle core metabolism and liver gene expression using RNA-Seq were investigated. Zebrafish maximum speed was correlated with body length and was significantly increased after 2 weeks of training. Maximum swim speed further increased after 8 weeks of training in both the normal-fed and the overfed groups, but training was found not to be sufficient in preventing weight gain in overfed fish. Metabolome and transcriptome profiling in trained fish exhibited increased blood glucose levels in the short-term and upregulated energy supply pathways as well as response to oxidative stress in the long-term. In conclusion, swim training is a valuable tool to study the effects of physical activity in zebrafish, which is accompanied by metabolic and transcriptional adaptations.

Shape memory alloy-driven undulatory locomotion of a soft biomimetic ray robot

The objective of this study was to imitate undulatory motion, which is a commonly observed swimming mechanism of rays, using a soft morphing actuator. To achieve the undulatory motion, an artificial muscle built with shape memory alloy-based soft actuators was exploited to control the shape-changing behavior of a soft fin membrane. Artificial undulating fins were divided into two categories according to the method of generating the wave motion: single and multiple actuator-driven fins. For empirical research on the transformation and propulsion behavior of each fin type, the design and construction of bound propulsors were undertaken to mimic the structural and behavioral aspects of animals. To visualize the effect of undulatory motion on the swimming efficiency test of the fin beat frequency, a simplified soft undulating fin with a rectangular propulsor was constructed and tested. Additionally, dynamic modeling of the fin tip in wave-traveling was conducted for comparison and optimization. To optimize the thrust and propulsion efficiency of robot speed, the effects of the wave amplitude control and actuator sequence on the fin behavior were examined. An untethered robot was constructed according to the experimental results of the propulsors. Both exhibited exceptional swimming efficiency and maneuverability. The multiple actuator-driven ray robot exhibited a maximum swimming speed of 0.25 body lengths per second which is almost a similar swimming speed with previously reported robots. The developed robot achieved directional swimming (forward and backward) and turning (including rotation). Underwater exploration in an artificial environment was performed using the robot.

Morphology of the limb, shell and head explain the variation in performance and ecology across 14 turtle taxa (12 species)

Abstract Given that morphology directly influences the ability of an organism to utilize its habitat and dietary resources, it also influences fitness. Comparing the relationship between morphology, performance and ecology is fundamental to understand how organisms evolve to occupy a wide range of habitats and diets. In turtles, studies have documented important relationships between morphology, performance and ecology, but none was field based or considered limb, shell and head morphology simultaneously. We compared the morphology, performance and ecology of 14 turtle taxa (12 species) in Mexico that range in their affinity to water and in their diet. We took linear measurements of limb, shell and head variables. We measured maximum swimming speed, maximum bite force and how often turtles were encountered on land, and we used stable isotopes to assess trophic position. We used these data to test the following three hypotheses: (1) morphology, performance and ecology covary; (2) limb and shell variables, like hand length, are correlated with swimming speed and the percentage of time spent on land; and (3) head variables, such as head width, are correlated with bite force and stable isotopes. We find support for these hypotheses and provide the first evidence that morphology influences performance and ecology in turtles in the field.

Ivermectin: A multilevel approach to evaluate effects in Prochilodus lineatus (Valenciennes, 1836) (Characiformes, Prochilodontidae), an inland fishery species

Ivermectin (IVM) is one of the most widely used antiparasitics worldwide. It is a potent and effective drug for treatment and prevention of internal and external parasitic infections of livestock and humans. IVM is excreted unchanged in manure of treated animals. Thus, residues of IVM may reach aquatic systems, affecting non-target organisms such as fish. Although the presence of IVM in aquatic environments has been reported, a multilevel approach (from cellular to behavioral responses) is necessary to determine the health of exposed organisms and the environmental risks associated. The aim of the present study was to investigate the response of the Neotropical fish Prochilodus lineatus, one of the main target species of South American freshwater fisheries, exposed to environmental concentrations of IVM: low (0.5 μg L−1) and high (1.5 μg L−1). Behavioral responses were assessed in juvenile fish and included water column use, routine swimming, total distance travelled, total activity time and Maximum swimming speed achieved during the escape response. Biochemical/oxidative stress responses assessed included brain acetylcholinesterase (AChE), catalase (CAT) and glutathione S-transferase (GST) activities; total antioxidant competence against peroxyl radicals (ACAP) and lipid oxidative damage (TBARs). Hematological biomarker responses included blood glucose levels, hematocrit, hemoglobin concentration, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, and mean corpuscular volume. Condition factor and hepatosomatic index were also calculated. The lowest IVM concentration caused a significant decrease in GST activity and maximum swimming speed during the escape response. Multivariate analysis with biochemical/stress and behavioral data revealed overall effects of IVM treatments. This multilevel analysis shows detrimental effects related to swimming behavior and predator avoidance which could affect population size and size-structure of P. lineatus. To our knowledge this is the first attempt to assess the effects of IVM on Neotropical fishes using an integrative approach based on biomarkers from different levels of biological organization.

Effects of elevated temperature and dietary additives Thermal Care™, Bio-Mos®, and GroBiotic® A on rainbow trout (Oncorhynchus mykiss) performance

This study examined the effects of elevated temperature and dietary Thermal Care, Bio-Mos and GroBiotic A on production performance and blood chemistry parameters in rainbow trout (Oncorhynchus mykiss). Rainbow trout under supraoptimal thermal conditions (18 °C) exhibited increased growth and feed intake but no change in feed efficiency for 6 weeks. This suggests that rearing fish at 18 °C may enhance production performance during the early stages of the grow-out process. By 12 weeks, fish at 18 °C showed increased feed intake, decreased feed efficiency, but no change in growth. Additionally, fish at 18 °C had lower protein content, protein retention efficiency, and energy retention efficiency. Elevated temperature did not change relative maximum swimming speed but did increase hematological parameters, thereby increasing the fish's oxygen supply capacity. There was preliminary evidence that Thermal Care improved rainbow trout growth under optimal thermal conditions (15 °C). However, fish fed Thermal Care at 18 °C exhibited increased feed intake but one of the lowest final fish weights leading to the lowest feed efficiency. Additionally, Grobiotic A impacted acid-base balance through changes in blood pH, TCO2, and HCO3− although the relevance of these interactions remains to be determined. By the end of the experiment, there were no noticeable benefits of including Thermal Care or Bio-Mos or GroBiotic A on production performance at either culture temperature.

Trout-like multifunctional piezoelectric robotic fish and energy harvester

This work presents our experimental studies on a trout-inspired multifunctional robotic fish as an underwater swimmer and energy harvester. Fiber-based flexible piezoelectric composites with interdigitated electrodes, specifically macro-fiber composite (MFC) structures, strike a balance between the deformation and actuation force capabilities to generate hydrodynamic propulsion without requiring additional mechanisms for motion amplification. A pair of MFC laminates bracketing a passive fin functions like artificial muscle when driven out of phase to expand and contract on each side to create bending. The trout-like robotic fish design explored in this work was tested for both unconstrained swimming in a quiescent water tank and under imposed flow in a water tunnel to estimate the maximum swimming speed, which exceeded 0.25 m s−1, i.e., 0.8 body lengths per second. Hydrodynamic thrust characterization was also performed in a quiescent water setting, revealing that the fin can easily produce tens of mN of thrust, similar to its biological counterpart for comparable swimming speeds. Overall, the prototype presented here generates thrust levels higher than other smart material-based concepts (such as soft polymeric material-based actuators which provide large deformation but low force), while offering simple design, geometric scalability, and silent operation unlike motor-based robotic fish (which often use bulky actuators and complex mechanisms). Additionally, energy harvesting experiments were performed to convert flow-induced vibrations in the wake of a cylindrical bluff body (for different diameters) in a water tunnel. The shed vortex frequency range for a set of bluff body diameters covered the first vibration mode of the tail, yielding an average electrical power of 120 μW at resonance for a flow speed around 0.3 m s−1 and a bluff body diameter of 28.6 mm. Such low-power electricity can find applications to power small sensors of the robotic fish in scenarios such as ecological monitoring, among others.

Swimming capability of target fish from eight hydropower stations in China relative to fishway design

The four major Chinese carp (MC), Schizothorax fish species (SF), and Cobitidae fish species (CF) are the most important target fish species in China. The swimming behaviour study of three target fish groups is the key to Chinese fishway designs. The 20 min critical swimming speed (Ucrit-20 min) and endurance of the target fish species in relation to body length, swimming speed, and water temperature were estimated using multiple linear regression. The results indicated that both fish body length and water temperature had a significant effect on swimming capability. Performance comparisons indicated that SF were remarkably strong swimmer. CF possess slightly greater swimming capability than MC. The entrance velocity of the upstream fishway should be greater than Ucrit-20 min, but less than maximum swimming speed to make the flow out of the fishway noticeable. The maximum swimming distance could be estimated using endurance model at flow velocity of 1.2 m·s–1. For the downstream-migrating juvenile fish, it was suggested that the flow velocity of turbine intake should be less than maximum sustained speed avoiding entering turbine.

Scaling and development of elastic mechanisms: the tiny strikes of larval mantis shrimp.

Latch-mediated spring actuation (LaMSA) is used by small organisms to produce high acceleration movements. Mathematical models predict that acceleration increases as LaMSA systems decrease in size. Adult mantis shrimp use a LaMSA mechanism in their raptorial appendages to produce extremely fast strikes. Until now, however, it was unclear whether mantis shrimp at earlier life-history stages also strike using elastic recoil and latch mediation. We tested whether larval mantis shrimp (Gonodactylaceus falcatus) use LaMSA and, because of their smaller size, achieve higher strike accelerations than adults of other mantis shrimp species. Based on microscopy and kinematic analyses, we discovered that larval G. falcatus possess the components of, and actively use, LaMSA during their fourth larval stage, which is the stage of development when larvae begin feeding. Larvae performed strikes at high acceleration and speed (mean: 4.133×105rads-2, 292.7 rad s-1; 12 individuals, 25 strikes), which are of the same order of magnitude as for adults - even though adult appendages are up to two orders of magnitude longer. Larval strike speed (mean: 0.385 m s-1) exceeded the maximum swimming speed of similarly sized organisms from other species by several orders of magnitude. These findings establish the developmental timing and scaling of the mantis shrimp LaMSA mechanism and provide insights into the kinematic consequences of scaling limits in tiny elastic mechanisms.

Toxicity and risk assessment of six widely used pesticides on embryo-larval development of the Pacific oyster, Crassostrea gigas.

This study aims to assess the toxic effects and the potential risk of widely used agricultural pesticides on the development (malformations and developmental arrest), growth and swimming activity of oyster D-larvae (Crassostrea gigas). Freshly fertilized oyster embryos were exposed for 24h at 24°C to different concentrations (0, 0.01, 0.1, 1 and 10μg.L-1) of six different pesticides: Glyphosate and its commercial solution (Roundup), Isoproturon, Nicosulfuron, Chlortoluron and Boscalid. The six pesticides tested induced a significant increase in larval malformations and developmental arrests. All pesticides except Glyphosate and Isoproturon affected larval growth. Roundup, Nicosulfuron, Chlortoluron and Boscalid also affected the swimming behaviour of the D-larvae, with a significant decrease recorded in their maximum swimming speed. Comparison of the LOEC (Lowest-Observed-Effect Concentration) of each compound led to the following toxicity classification: Boscalid > Chlortoluron=Nicosulfuron > Glyphosate > Roundup > Isoproturon, with respectively LOEC of 0.0028; 0.015; 0.017; 0.11; 0.3 and 0.78μg.L-1. By comparison of the maximum concentrations in the Pertuis Charentais (South West, France) and LOEC of each pesticide, the following risk scale was obtained: Chlortoluron > Boscalid > Glyphosate > Roundup > Nicosulfuron > Isoproturon. Our results revealed that Chlortoluron, Boscalid and to a lesser extent Glyphosate represent a potential threat to early life stages of oyster living in the Pertuis Charentais marine area.

Design of cylindrical soft vacuum actuator for soft robots

Soft robots have been significantly studied in recent decades, and among their key components are soft actuators. Vacuum is one of the main drivers of soft actuators. In this study, we propose a novel cylindrical soft vacuum actuator (CSVA) consisting of a top layer, bottom layer, and cylindrical internal chamber. Under a vacuum, the bottom layer was concaved into the internal chamber. A simplified analytical model was established to analyze the relationship between the vacuum pressure and the deformation height of the bottom layer. A validation experiment was conducted to verify the effectiveness of the proposed analytical model. The potential applications of the CSVA in the design of soft robots were also explored. A jellyfish-inspired swimming robot, an octopus-inspired suction cup, and a soft–rigid gripper were designed according to the concave deformation of the bottom layer. Then, the swimming speed of the swimming robot, the adsorption force of the suction cup, and the grasping capability of the soft–rigid gripper were investigated. The experimental results show that the maximum swimming speed of the swimming robot is 55.3 mm s−1 at a flapping frequency of 0.6 Hz. The adsorption forces of the suction cup both in air and underwater are 16.8 N and 17.5 N, respectively. The soft–rigid gripper with a pinching-grasping mode can grasp objects of various shapes and sizes in air and underwater. The experimental results demonstrate the feasibility of the soft vacuum actuator in the design of various soft robots.

Fish Specialize Their Metabolic Performance to Maximize Bioenergetic Efficiency in Their Local Environment: Conspecific Comparison Between Two Stocks of Pacific Chub Mackerel (Scomber japonicus)

Species-specific ecological traits in fishes are likely to vary between populations or stocks due to differences in regional oceanic conditions, such as latitudinal temperature. We examined potential intraspecific differences in the swimming performance and metabolism of Pacific chub mackerel (Scomber japonicus) from the Northwest and Northeast Pacific stocks, which are distributed on opposite sides of the North Pacific at similar latitudes, but where the temperature contrast is large. Swimming bioenergetics and metabolic data of Northwest stock mackerel were measured at 14, 18, and 24°C using variable-speed swim-tunnel respirometers, and then the resulting bioenergetic parameters were compared with previous findings from the Northeast stock. At a given size, the maximum sustainable swimming speed (Umax) of the Northwest stock showed no significant difference compared to the Northeast stock at 18 and 24°C, but was lower at 14°C. In addition, the oxygen consumption rate (MO2) of the Northwest stock showed lower mass dependence and different temperature dependence at a given swimming speed than in the Northeast stock. Combined with stock-specific data on growth and experienced temperatures in the wild, these bioenergetic differences indicate that the swimming performance and metabolism of the two stocks are specific to their local environment to maximize bioenergetic efficiency.

Hydrodynamic Modeling and Design of Robotic Fish using Slender Body Theory

Design of bio-inspired robotic fish has been an important area of research for applications such as water quality monitoring, aquatic animal behavioral study and underwater exploration. The modeling of robotic fish requires high dimensional analysis, which increases the design complexity. To address this complexity, approximate models are preferred and frequently used in the design of robotic fishes. The accuracy of these models mainly relies on various hydrodynamic parameter identification of which drag coefficient estimation is highly challenging. This paper utilizes a simple deceleration motion model to estimate the drag coefficient effectively so that the linearization error is reduced. The non-linearity in the deceleration model is simplified and mapped as a linear model to predict the drag coefficient. The estimated drag coefficient is used for dynamic modeling of robotic fish using slender body theory. The dynamic model is validated through experimental setup using accelerometer and visual sensor data. The maximum swimming speed of 0.32 ms-1 is achieved at 1.2 Hz caudal fin oscillations.

Exploration of swimming performance for a biomimetic multi-joint robotic fish with a compliant passive joint

In this paper, a novel compliant joint with two identical torsion springs is proposed for a biomimetic multi-joint robotic fish, which enables imitatation of the swimming behavior of live fish. More importantly, a dynamic model based on the Lagrangian dynamic method is developed to explore the compliant passive mechanism. In the dynamic modeling, a simplified Morrison equation is utilized to analyze the hydrodynamic forces. Further, the parameter identification technique is employed to estimate numerous hydrodynamic parameters. The extensive experimental data with different situations match well with the simulation results, which verifies the effectiveness of the obtained dynamic model. Finally, motivated by the requirement for performance optimization, we firstly take advantage of a dynamic model to investigate the effect of joint stiffness and control parameters on the swimming speed and energy efficiency of a biomimetic multi-joint robotic fish. The results reveal that phase difference plays a primary role in improving efficiency and the compliant joint presents a more significant role in performance improvement when a smaller phase difference is given. Namely, at the largest actuation frequency, the maximum improvement of energy efficiency is obtained and surprisingly approximates 89%. Additionally, the maximum improvement in maximum swimming speed is about 0.19 body lengths per second. These findings demonstrate the potential of compliance in optimizing joint design and locomotion control for better performance.

Novel hydraulic guidelines can assist upstream fish passage through smooth box culverts

ABSTRACT Culverts are important hydraulic structures for delivering a range of valuable socioeconomic services; however, they are also known to have negative impacts on freshwater and estuarine river systems, including the blockage of upstream fish passage, particularly small-bodied fish species. Herein new guidelines are proposed for fish-friendly multi-cell smooth box culvert designs, with a focus on small-bodied Australian native fish species and juveniles of larger fish. The new set of hydraulic engineering design guidelines, in the process of being implemented in New South Wales (Australia), optimise culvert design for fish passage for water discharges Q < QT = 0.1× Qdes, for which the reduced-velocity zone (RVZ) represents 15% of the flow area where 0 < Vx < Ufish, with Vx the local time-averaged longitudinal velocity component and Ufish the maximum prolonged swimming speed of target fish species. After a presentation of the basic concepts, a design application is developed based upon a real-world case study in north-eastern New South Wales (Australia). The novel approach relies upon a sound understanding of the velocity flow in the box culvert barrel at less-than-design discharges to accurately characterise the RVZ next to the barrel walls and corners, combined with a detailed understanding of the swimming performance and behaviour of native fish species.

Speed and directedness predict colonization sequence post-disturbance.

Foundational ecological models characterize dispersal with two behavioral traits, speed and directional bias. We hypothesized that these two traits can predict the order of colonization by fishes in a heterogenous landscape. Colonization patterns following hydrological disturbance were documented from a 20-year multi-site time series of marsh fish, and we evaluated the ability of a two-parameter model to predict these patterns. The maximum aerobic swimming speed (UCRIT) for six coexisting fish species were estimated using endurance tests; field estimates of directedness and swimming speed were previously documented using encounter samplers. We incorporated interspecific variation in speed, direction, and density into several Agent Based Modelsto simulate dispersal following disturbance. Six virtual "species" with varying levels of directedness, "swam" in an artificial environment to reach a refuge habitat. The time of first arrival for each species was saved at the end of each run and used to calculate the probability of arrival order. Our simulated results generated predictions on order of arrival consistent with observed colonization patterns in our long-term dataset. Swim tunnel results revealed that fast (high UCRIT) estimates were characteristic of early colonizing species; whereas, slow (low UCRIT) estimates were characteristic of late colonizing species. Directional bias better predicted order of arrival than speed and was robust to inter-specific variation in density. This study demonstrated that two parameters were adequate to predict the order of species colonization in a complex landscape. These results support the use of relatively simple trait-based models to generate realistic community assembly dynamics.

Fibrous Flagellar Hairs of Chlamydomonas reinhardtii Do Not Enhance Swimming

The flagella of Chlamydomonas reinhardtii possess fibrous ultrastructures of a nanometer-scale thickness known as mastigonemes. These structures have been widely hypothesized to enhance flagellar thrust; however, detailed hydrodynamic analysis supporting this claim is lacking. In this study, we present a comprehensive investigation into the hydrodynamic effects of mastigonemes using a genetically modified mutant lacking the fibrous structures. Through high-speed observations of freely swimming cells, we found the average and maximum swimming speeds to be unaffected by the presence of mastigonemes. In addition to swimming speeds, no significant difference was found for flagellar gait kinematics. After our observations of swimming kinematics, we present direct measurements of the hydrodynamic forces generated by flagella with and without mastigonemes. These measurements were conducted using optical tweezers, which enabled high temporal and spatial resolution of hydrodynamic forces. Through our measurements, we found no significant difference in propulsive flows due to the presence of mastigonemes. Direct comparison between measurements and fluid mechanical modeling revealed that swimming hydrodynamics were accurately captured without including mastigonemes on the modeled swimmer’s flagella. Therefore, mastigonemes do not appear to increase the flagella’s effective area while swimming, as previously thought. Our results refute the longstanding claim that mastigonemes enhance flagellar thrust in C. reinhardtii, and so, their function still remains enigmatic.

Maxed Out: Optimizing Accuracy, Precision, and Power for Field Measures of Maximum Metabolic Rate in Fishes.

Both laboratory and field respirometry are rapidly growing techniques to determine animal performance thresholds. However, replicating protocols to estimate maximum metabolic rate (MMR) between species, populations, and individuals can be difficult, especially in the field. We therefore evaluated seven different exercise treatments-four laboratory methods involving a swim tunnel (critical swim speed [Ucrit], Ucrit postswim fatigue, maximum swim speed [Umax], and Umax postswim fatigue) and three field-based chasing methods (3-min chase with 1-min air exposure, 3-min chase with no air exposure, and chase to exhaustion)-in adult coho salmon (Oncorhynchus kisutch) as a case study to determine best general practices for measuring and quantifying MMR in fish. We found that all seven methods were highly comparable and that chase treatments represent a valuable field alternative to swim tunnels. Moreover, we caution that the type of test and duration of measurement windows used to calculate MMR can have significant effects on estimates of MMR and statistical power for each approach.

Behavioral Characterization ofdmrt3aMutant Zebrafish Reveals Crucial Aspects of Vertebrate Locomotion through Phenotypes Related to Acceleration

Vertebrate locomotion is orchestrated by spinal interneurons making up a central pattern generator. Proper coordination of activity, both within and between segments, is required to generate the desired locomotor output. This coordination is altered during acceleration to ensure the correct recruitment of muscles for the chosen speed. The transcription factor Dmrt3 has been proposed to shape the patterned output at different gaits in horses and mice. Here, we characterized dmrt3a mutant zebrafish, which showed a strong, transient, locomotor phenotype in developing larvae. During beat-and-glide swimming, mutant larvae showed fewer and shorter movements with decreased velocity and acceleration. Developmental compensation likely occurs as the analyzed behaviors did not differ from wild-type at older larval stages. However, analysis of maximum swim speed in juveniles suggests that some defects persist within the mature locomotor network of dmrt3a mutants. Our results reveal the pivotal role Dmrt3 neurons play in shaping the patterned output during acceleration in vertebrates.