Routine Swimming Research Articles

Movement Behavior of the Dusky Grouper Epinephelus marginatus (Lowe, 1834) in Early Life Stages

The dusky grouper (Epinephelus marginatus) is a vulnerable predatory fish found in the Atlantic and Indian oceans, and in the Mediterranean Sea. This study investigates the movement patterns of grouper larvae (151 individuals) during their first feeding period (three to ten days post hatching) through laboratory experiments offering rotifers (Brachionus sp.) and copepod nauplii as food. High-speed cameras and imaging techniques including bright field microscopy, matched filters, and holography captured rapid displacements (up to 25 body lengths per second), peduncle caudal beats (up to 40 beats s−1), turns, and resting periods. Reynolds numbers ranged from <45 for routine swimming to 222 for burst swimming. Specific behaviors, including changes in swimming velocity and body movements, were observed from three days post hatching, when feeding begins, suggestive of an array of responses to environmental forcing, predator avoidance, food search, and feeding success. These findings provide insights into the critical movement performances of E. marginatus larvae, which help to unravel their ecological interactions and survival strategies. Understanding grouper larval swimming behavior is pivotal for devising effective cultivation strategies aimed at replenishing wild stocks and enhancing production for human consumption.

Kinematic characteristics of calanoid copepod appendage motion

Abstract Propulsion by copepods requires high-speed video and intensive analyses. Routine smooth swimming is compared with small relocation jumps and escape reactions, relying on kinematics analyses of appendage movement. In this study, we used high-speed video at 1200 frames per second to determine the kinematic parameters of three types of swimming in Eurytemora affinis females: routine steady swimming, small relocation jumps and escape reactions. The average speed varied in the range 0.30–0.82 cm s−1 during steady routine swimming. This value increased to 4.48 ± 1.01 cm s−1 during small relocation jumps, and reached 21.94 ± 2.68 cm s−1 during escape reactions. The small angular amplitude (40–50°) and the very high beat frequency (63–80 Hz) of the cephalic appendages during routine swimming indicate that E. affinis is a feeding-current feeder. The comparison of the angular displacements of the antennules, thoracic legs and abdomen with respect to the movement speed demonstrates that, both in the case of small relocation jumps and during escape reactions, the main propulsive role is played by the thoracic swimming legs and abdomen.

Influence of egg sacs on the swimming performance of freshwater cyclopoid copepods

Abstract Female cyclopoid copepods carry their embryos in egg sacs that impact swimming performance until nauplii hatch. We studied kinematic parameters and mechanical energy of small routine jumps and large escape jumps of non-egg-carrying (NEC) and egg-carrying (EC) females of Mesocyclops leuckarti and Macrocyclops albidus. The drag and body acceleration costs for EC females of M. leuckarti and M. albidus during routine jumps were 28 and 40%, respectively, higher than those for NEC females moving at the same speed. Maintaining position in the water column by small jumps was more costly for EC females, requiring 2.2–2.3 times more jumps and energy. Consequently, the persistence of EC females was limited in the open water. In M. leuckarti and M. albidus, the average speed and distances of jumps were 5–6 and 1.5–2.2 times higher, respectively, and the duration of jumps was 2.2–2.5 times shorter during escape than routine swimming. The maximum jumping speeds of NEC females, 40.6 and 50.5 cm s−1, respectively, were 12–14% higher than those of EC females, whereas their power and cost of transport were 16 and 23% lower, respectively. These results clearly indicated that egg sacs impair swimming and increase energetic costs of movement.

Effects of Water Temperature and Structural Habitat Complexity on the Routine Swimming Speed and Escape Response of Post-Settlement Stage White Seabream

Coastal habitats are increasingly threatened by multiple anthropogenic-related activities, which include ocean warming and loss of structural habitat complexity. These two pressures have the potential to severely affect the structure and function of marine biodiversity. Early life stages of many fish species recruit to coastal habitats at the end of their pelagic phase, benefiting from access to food, shelter and protection. However, changes in temperature have been shown to influence ecologically relevant behaviours in post-settlement stage fish, and the loss of structural habitat complexity has been related to low recruitment and deleterious behaviours of fish in coastal habitats. Here, we evaluated the individual and interactive effects of prolonged exposure to increasing temperature and changed structural habitat complexity on routine swimming speed and escape response of post-settlement white seabream, Diplodus sargus (Linnaeus, 1758). Fish were reared under different temperatures (control 19 °C; high 22 °C) and structural habitat complexity (low and high) scenarios, in a cross-experimental design, and the routine swimming and escape responses were analyzed after 6 weeks of exposure. Change in temperature did not induce alterations at the behavioural level, but loss of structural habitat complexity increased speed and distance travelled during routine swimming, and responsiveness to a stimulus during the escape response behaviour. The interaction of the two factors did not influence performance. Determining how species are affected by changes in their environment, and the mechanisms that underlie these changes, will be critical to understanding the fish recruitment and populations’ fitness and survival.

Warming affects routine swimming activity and novel odour response in larval zebrafish

Temperature is a primary factor affecting the physiology of ectothermic animals and global warming of water bodies may therefore impact aquatic life. Understanding the effects of near-future predicted temperature changes on the behaviour and underlying molecular mechanisms of aquatic animals is of particular importance, since behaviour mediates survival. In this study, we investigate the effects of developmental temperature on locomotory behaviour and olfactory learning in the zebrafish, Danio rerio. We exposed zebrafish from embryonic stage to either control (28 °C) or elevated temperature (30 °C) for seven days. Overall, warming reduced routine swimming activity and caused upregulation of metabolism and neuron development genes. When exposed to olfactory cues, namely catfish cue, a non-alarming but novel odour, and conspecifics alarming cue, warming differently affected the larvae response to the two cues. An increase in locomotory activity and a large transcriptional reprogramming was observed at elevated temperature in response to novel odour, with upregulation of cell signalling, neuron development and neuron functioning genes. As this response was coupled with the downregulation of genes involved in protein translation and ATP metabolism, novel odour recognition in future-predicted thermal conditions would require energetic trade-offs between expensive baseline processes and responsive functions. To evaluate their learning abilities at both temperatures, larvae were conditioned with a mixture of conspecifics alarm cue and catfish cue. Regardless of temperature, no behavioural nor gene expression changes were detected, reinforcing our findings that warming mainly affects zebrafish molecular response to novel odours. Overall, our results show that future thermal conditions will likely impact developing stages, causing trade-offs following novel olfactory detection in the environment.

Exposure to petroleum-derived and biopolymer microplastics affect fast start escape performance and aerobic metabolism in a marine fish

Evidence suggests that petroleum-derived polymers can impact marine organisms however, little is understood about whether biopolymers affect the behaviour and physiology of marine teleost fish. The aim of this research was to examine the potential effects of microplastics from a petroleum-derived polymer, (polyethylene, PE), and a biopolymer, (edible food coating EFC) on the escape performance, routine swimming, and aerobic metabolism of Forsterygion capito (the mottled triplefin). PE exposure negatively affected fish through longer latencies (∼25 % slower to respond), slower maximum speeds and higher responsiveness in escape performance compared to control fish. Furthermore, fish exposed to PE displayed slower mean speeds and reduced the distance travelled by ∼25 %. After an exhaustive challenge, PE-exposed fish showed higher excess post-exercise oxygen consumption during recovery, compared to control fish. By contrast, EFC exposure only negatively affected maximum speed during an escape. Directionality and mean speed in escape performance, metabolic rate and recovery time were unaffected by biopolymer exposure. With the ever-increasing number of microplastics in the ocean, a shift to biodegradable polymers may be beneficial to marine organisms due to the smaller effect found when compared to petroleum-derived polymers in this study. As a central tool for conservation, this study represents a significant advance to predict the impact of microplastics on wild fish populations.

Gene expression underlying variation in the survival skills of red drum larvae (Sciaenops ocellatus).

Mortality rates of marine fish larvae are incredibly high and can determine year-class strength. The major causes of larval mortality are predation and starvation, and the performance of larvae in survival skills that can mitigate this mortality (predator evasion, foraging) varies among individuals and cohorts, but the causes of the variation are not known. Transcriptomics can link gene expression variation to phenotypic variation at the whole-system level to investigate the molecular basis of behavioural variation. We used tag-based RNA-sequencing to examine the molecular basis of variation in predator evasion and routine swimming (trait related to foraging efficiency) in the larval red drum, Sciaenops ocellatus. We looked for functional gene networks in which interindividual variation would explain variation in larval behavioural performance. We identified co-expressed gene groups ("modules") associated with predator evasion traits and found enrichment of motor, neural and energy metabolism pathways. These functional associations and pattern of correlations between modules and traits suggest that energy availability and allocation were responsible for the magnitude of startle responses, while differential neural and motor activation were associated with differences in response latency.

Distributed propulsion enables fast and efficient swimming modes in physonect siphonophores

Many fishes employ distinct swimming modes for routine swimming and predator escape. These steady and escape swimming modes are characterized by dramatically differing body kinematics that lead to context-adaptive differences in swimming performance. Physonect siphonophores, such as Nanomia bijuga, are colonial cnidarians that produce multiple jets for propulsion using swimming subunits called nectophores. Physonect siphonophores employ distinct routine and steady escape behaviors but-in contrast to fishes-do so using a decentralized propulsion system that allows them to alter the timing of thrust production, producing thrust either synchronously (simultaneously) for escape swimming or asynchronously (in sequence) for routine swimming. The swimming performance of these two swimming modes has not been investigated in siphonophores. In this study, we compare the performances of asynchronous and synchronous swimming in N. bijuga over a range of colony lengths (i.e., numbers of nectophores) by combining experimentally derived swimming parameters with a mechanistic swimming model. We show that synchronous swimming produces higher mean swimming speeds and greater accelerations at the expense of higher costs of transport. High speeds and accelerations during synchronous swimming aid in escaping predators, whereas low energy consumption during asynchronous swimming may benefit N. bijuga during vertical migrations over hundreds of meters depth. Our results also suggest that when designing underwater vehicles with multiple propulsors, varying the timing of thrust production could provide distinct modes directed toward speed, efficiency, or acceleration.

Body shape and mode of propulsion do not constrain routine swimming in coral reef fishes

AbstractIt is widely believed that because of biomechanical trade‐offs, fish body shape and the mode of propulsion are strong predictors of swimming performance, with the best cruisers, maneuverers and accelerators having different body forms and emphasizing different propulsion mechanisms. This paradigm is regularly projected onto routine swimming behaviour and dominates the ecomorphological literature, despite the paucity of field measurements.In this study, we measured variation in swimming behaviour among 48 species of Indian Ocean coral reef fishes using recordings from a remote stereo video system. We measured average swimming speed, average swimming bout distance, frequency of turns and percent of time spent station‐holding and looked for the predicted trade‐offs between them.We find little evidence of the expected relationships between swimming behaviours across species, little evidence that body shape affects swimming and few differences between species that swim by undulating the body and those that emphasize the use of median and paired fins. Taxa widely thought of as archetypical maneuverers (Chaetodon) and cruisers (Caranx) were not outliers in any behaviours.Our results indicate that swimming behaviour is not easily predicted from simple measures of body shape and that alternative swimming modes can produce comparable behavioural profiles.Read the freePlain Language Summaryfor this article on the Journal blog.

The predominant stride-frequency for routine swimming in catsharks (Scyliorhinus canicula) generates high power at high efficiency in the red musculature

Videos of free swimming of catsharks (Scyliorhinus canicula) were analysed to give values of swimming speed (units: FL (fish lengths) s−1), stride-length (forward movement in the direction of travel per cycle of body undulation (units: FL) and stride-frequency (units: s−1). Most of the swims (139 of 163, 85%) were at speeds less than 0.545 FL s−1 and were categorized as slow. The rest (24/163, 15%) were categorized as fast. Stride-lengths and stride-frequencies could be evaluated for 115 of the slow swims and 16 of the fast swims. We discuss the fast swim results, but there were so few fast swims that no firm conclusions could be made. As swim speed increased during slow swims, there was a strong increase stride-length [slope 0.965, P < 0.0001)] and a small increase in stride-frequency. Most stride-frequencies (70/115, 61%) were in the range 0.68–0.88 s−1. Previous experiments on red muscle isolated of catshark showed that in this range of frequencies of sinusoidal movement, high power was produced at high efficiency (Curtin and Woledge b). Lower frequencies gave less power and at higher frequencies the efficiency of energy conversion was lower. Thus, we conclude that during routine swimming catsharks choose a swimming speed that optimizes red muscle performance in terms of power and efficiency.

Visual object detection biases escape trajectories following acoustic startle in larval zebrafish

In this study, we investigated whether the larval zebrafish is sensitive to the presence of obstacles in its environment. Zebrafish execute fast escape swims when in danger of predation. We posited that collisions with solid objects during escape would be maladaptive to the fish, and therefore, the direction of escape swims should be informed by the locations of barriers. To test this idea, we developed a closed-loop imaging rig outfitted with barriers of various qualities. We show that when larval zebrafish escape in response to a non-directional vibrational stimulus, they use visual scene information to avoid collisions with obstacles. Our study demonstrates that barrier avoidance rate corresponds to the absolute distance of obstacles, as distant barriers outside of collision range elicit less bias than nearby collidable barriers that occupy the same amount of visual field. The computation of barrier avoidance is covert: the fact that fish will avoid barriers during escape cannot be predicted by its routine swimming behavior in the barrier arena. Finally, two-photon laser ablation experiments suggest that excitatory bias is provided to the Mauthner cell ipsilateral to approached barriers, either via direct excitation or a multi-step modulation process. We ultimately propose that zebrafish detect collidable objects via an integrative visual computation that is more complex than retinal occupancy alone, laying a groundwork for understanding how cognitive physical models observed in humans are implemented in an archetypal vertebrate brain. VIDEO ABSTRACT.

Ontogeny and ecological significance of metabolic rates in sea turtle hatchlings

BackgroundSea turtle hatchlings must avoid numerous predators during dispersal from their nesting beaches to foraging grounds. Hatchlings minimise time spent in predator-dense neritic waters by swimming almost continuously for approximately the first 24 h post-emergence, termed the ‘frenzy’. Post-frenzy, hatchling activity gradually declines as they swim in less predator-dense pelagic waters. It is well documented that hatchlings exhibit elevated metabolic rates during the frenzy to power their almost continuous swimming, but studies on post-frenzy MRs are sparse.ResultsWe measured the frenzy and post-frenzy oxygen consumption of hatchlings of five species of sea turtle at different activity levels and ages to compare the ontogeny of mass-specific hatchling metabolic rates. Maximal metabolic rates were always higher than resting metabolic rates, but metabolic rates during routine swimming resembled resting metabolic rates in leatherback turtle hatchlings during the frenzy and post-frenzy, and in loggerhead hatchlings during the post-frenzy. Crawling metabolic rates did not differ among species, but green turtles had the highest metabolic rates during frenzy and post-frenzy swimming.ConclusionsDifferences in metabolic rate reflect the varying dispersal stratagems of each species and have important implications for dispersal ability, yolk consumption and survival. Our results provide the foundations for links between the physiology and ecology of dispersal of sea turtles.

AWWA Water Science Author Spotlight

AWWA Water Science Author Spotlight

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 feeding condition on the morphology, behaviour and nutritional status of

Early life stages of migratory fish in rivers rely on physical transport mechanisms to carry them from spawning sites to distant nursery areas where they find food and refuge conditions. Starvation after a prolonged downriver drift could severely affect the colonisation and predator evasion capabilities of the larvae. In this study we investigated differences in the external morphology, nutritional condition and swimming abilities of fed and unfed Prochilodus lineatus early larvae under experimental conditions. After yolk reabsorption on Day 6, larvae were either fed with nauplii of Artemia salina or left unfed for up to 10 days. Larvae from each feeding regime (i.e. fed and unfed) were sampled daily from three aquaria, and the morphometry and routine swimming activity were determined and analysed together with a previously published RNA/DNA ratio dataset. The results were in agreement with previous investigations that indicated that the larvae of this species have starvation endurance; however, prolonged food deprivation is associated with a smaller body, anal depth and head length, as well as lower RNA/DNA ratios and reduced swimming ability.

Effects of Exposure to Low Concentrations of Oil on the Expression of Cytochrome P4501a and Routine Swimming Speed of Atlantic Haddock (Melanogrammus aeglefinus) Larvae In Situ.

Exposure to environmentally relevant concentrations of oil could impact survival of fish larvae in situ through subtle effects on larval behavior. During the larval period, Atlantic haddock (Melanogrammus aeglefinus) are transported toward nursery grounds by ocean currents and active swimming, which can modify their drift route. Haddock larvae are sensitive to dispersed oil; however, whether exposure to oil during development impacts the ability of haddock larvae to swim in situ is unknown. Here, we exposed Atlantic haddock embryos to 10 and 80 μg oil/L (0.1 and 0.8 μg ∑PAH/L) of crude oil for 8 days and used a novel approach to measure its effect on the larval swimming behavior in situ. We assessed the swimming behavior of 138 haddock larvae in situ, in the North Sea, using a transparent drifting chamber. Expression of cytochrome P4501a (cyp1a) was also measured. Exposure to 10 and 80 μg oil/L significantly reduced the average in situ routine swimming speed by 30–40% compared to the controls. Expression of cyp1a was significantly higher in both exposed groups. This study reports key information for improving oil spill risk assessment models and presents a novel approach to study sublethal effects of pollutants on fish larvae in situ.

Vessel noise affects routine swimming and escape response of a coral reef fish.

An increasing number of studies have shown that anthropogenic noise can negatively affect aspects of the anti-predator behaviour of reef fishes, potentially affecting fitness and survival. However, it has been suggested that effects could differ among noise sources. The present study compared two common sources of anthropogenic noise and investigated its effects on behavioural traits critical for fish survival. In a tank-based experiment we examined the effects of noise from 4-stroke motorboats and ships (bulk carriers > 50,000 tonnes) on the routine swimming and escape response of a coral reef fish, the whitetail damselfish (Pomacentrus chrysurus). Both 4-stroke boat and ship noise playbacks affected the fast-start response and routine swimming of whitetail damselfish, however the magnitude of the effects differed. Fish exposed to ship noise moved shorter distances and responded more slowly (higher response latency) to the startle stimulus compared to individuals under the 4-stroke noise treatment. Our study suggests that 4-stroke and ship noise can affect activity and escape response of individuals to a simulated predation threat, potentially compromising their anti-predator behaviour.

Jellyfish and Fish Solve the Challenges of Turning Dynamics Similarly to Achieve High Maneuverability

Turning maneuvers by aquatic animals are essential for fundamental life functions such as finding food or mates while avoiding predation. However, turning requires resolution of a fundamental dilemma based in rotational mechanics: the force powering a turn (torque) is favored by an expanded body configuration that maximizes lever arm length, yet minimizing the resistance to a turn (the moment of inertia) is favored by a contracted body configuration. How do animals balance these opposing demands? Here, we directly measure instantaneous forces along the bodies of two animal models—the radially symmetric Aurelia aurita jellyfish, and the bilaterally symmetric Danio rerio zebrafish—to evaluate their turning dynamics. Both began turns with a small, rapid shift in body kinematics that preceded major axial rotation. Although small in absolute magnitude, the high fluid accelerations achieved by these initial motions generated powerful pressure gradients that maximized torque at the start of a turn. This pattern allows these animals to initially maximize torque production before major body curvature changes. Both animals then subsequently minimized the moment of inertia, and hence resistance to axial rotation, by body bending. This sequential solution provides insight into the advantages of re-arranging mass by bending during routine swimming turns.

Effects of Interval Sprint Trainings on Heart Rate and 50 m Swimming Performances of Young Male Swimmers

Achieving superior performance in swimming, as in other sports, depends on the customization of training for young athletes. The aim of this study was to investigate the effects of sprint interval trainings on heart rate and 50 m swimming performances of young male swimmers. 24 young male swimmers joined to the study by having their parents confirm the &amp;ldquo;Parental Permission Form&amp;rdquo;. Swimmers randomly divided into two groups as normal training group and interval sprint training group. As normal training group continued the routine swimming training, interval sprint trainings (8 x 50 interval repeats in crawl and backstroke styles) were applied to the other group additionally for 8 weeks, 3 days a week, at least 30 min a day. Rested-maximum heart rate, 50 m sprint swimming test in crawl and backstroke styles were applied to the swimmers in 1st and 8th weeks of the period. The analysis of data was made in the statistical package program by using &amp;ldquo;Descriptive statistics&amp;rdquo;, &amp;ldquo;Paired t Test&amp;rdquo; and &amp;ldquo;Independent t Test&amp;rdquo; for comparison. Results of pre- and post-test comparison of each group, significant differences were found in resting heart rate values of normal training group and all values of interval sprint training group (p &amp;lt; .05). Results of comparison between groups, differences found statistically significant in 8th week maximum heart rate, crawl and backstroke performances (p &amp;lt; .05). To conclude, we could say that the reason of finding significant differences in rested and maximum heart rate is the positive effects of physical activity on the cardio-vascular system (adaptation). And, the reason for the positive effects on sprint interval performance is depended on sprint interval swimming was acute origination of body&amp;rsquo;s physiological reaction to rising energy need during short time and intensive physical activity even in micro plan.

Disc starts: the pectoral disc of stingrays promotes omnidirectional fast starts across the substrate

We explored how the flattened and rounded pectoral disc of the ocellate river stingray (Potamotrygon motoro (Müller and Henle, 1841)) enables them to use the benthic plane during fast-start escape. Escape responses were elicited via prodding different locations around the pectoral disc and were recorded using video. Modulation of pectoral-fin movements that power swimming enabled omnidirectional escape across the substrate, with similar performance in all directions of escape. Hence, translation of the body did not necessarily have to follow the orientation of the head, overcoming the constraint of a rigid body axis. An increase in prod speed was associated with an increase in initial translational speed and acceleration away from the prod. As prod location shifted towards the snout, yaw rotation increased, eventually reorienting the fish into a forward swimming position away from the prod. Furthermore, P. motoro yawed with essentially zero turning radius, allowing reorientation of the head with simultaneous rapid translation away from the prod, and yaw rate during escape was substantially greater than reported during routine swimming for stingrays. We conclude that stingrays employ a distinctive approach to escape along the substrate, which we have termed disc starts, that results in effective manoeuvrability across the benthic environment despite limited longitudinal flexibility of the body and that challenges the concept of manoeuvrability typically used for fishes.