Changes In Swimming Speed Research Articles

English

Background: The aims were to examine (i) the difference in swimming speed in breaststroke swimmers between short (SC) and long course (LC) and (ii) the change in swimming speed across years for elite female and male swimmers competing at national and international level. Methods: Swimming speed of breaststroke swimmers at national level (i.e. athletes listed in Swiss swimming high score list between 2000 and 2011) and at international level (i.e. finalists of World Championships between 2001 and 2012) were analyzed for three course distances (i.e. 50m, 100m and 200m) using linear regression analyses and analysis of variance. Results: Swimming speed was faster in SC than in LC in 50m (1.8-2.6%), 100m (2.2-3.6%) and 200m (2.6-4.2 %), respectively. Swimming speed increased between 1.2% and 5.2% both for SC and LC across years, independently of the sex and the distance. For all distances, the sex difference was greater in LC than in SC. Mean values for the sex difference in swimming speed at national level were 12.1% in SC versus 11.9% in LC for 50 m, 11.9% in SC versus 11.3% in LC for 100m and 11.0% in SC versus 10.7% in LC for 200m, with significant difference only for 200m LC (p=0.03). Mean values for sex difference in swimming speed at international level were 13.3% in SC versus 12.7% in LC for 50m, 12.6% in SC versus 11.9% in LC for 100m and 12.1% in SC versus 11.2% in LC for 200m, only with significance for 100m SC (p=0.01). Conclusion: Elite breaststroke swimmers were ∼3% faster on SC compared to LC. The sex difference in breaststroke swimming speed from 50m to 200m events was ~11% (with significance at national level on 200m LC and on international level on 100m SC) but appeared slightly greater in LC compared to SC.

Optimization of transit strategies while diving in foraging king penguins

AbstractOptimal foraging theories predict that air‐breathing, diving foragers should maximize time spent at feeding depths, and minimize time spent travelling between surface and depth (transits). The second part of this hypothesis was tested in free‐ranging king penguins Aptenodytes patagonicus using measurements of vertical speed, swimming speed, body angle and flipper stroke frequency during transits in relation to an index of foraging success (number of wiggles), during the bottom and the ascent phases of the dive. We found that, except for flipper stroke frequency, all measured variables increased with diving depth and foraging activity. The change in vertical speed was driven mainly by a change in body angle and a slight change in swimming speed. These results suggest a shortening of transit duration in response to increased foraging activity. Whereas the time spent commuting between the surface and foraging depths was reduced when foraging activity was high, vertical speed was only at its maximum over a small part of both ascent and descent phases of the dive. Within the first 10 m of descent, vertical speed increased with maximum dive depth and an index of foraging activity, suggesting that penguins anticipated their diving depth and foraging activity. Our results show that foraging king penguins adjust their diving behaviour in response to both diving depth and foraging activity. Further studies should consider ecological, physiological or mechanical constraints as factors that may limit foraging optimization.

Brief embryonic strychnine exposure in zebrafish causes long-term adult behavioral impairment with indications of embryonic synaptic changes

Zebrafish provide a powerful model of the impacts of embryonic toxicant exposure on neural development that may result in long-term behavioral dysfunction. In this study, zebrafish embryos were treated with 1.5mM strychnine for short embryonic time windows to induce transient changes in inhibitory neural signaling, and were subsequently raised in untreated water until adulthood. PCR analysis showed indications that strychnine exposure altered expression of some genes related to glycinergic, GABAergic and glutamatergic neuronal synapses during embryonic development. In adulthood, treated fish showed significant changes in swimming speed and tank diving behavior compared to controls. Taken together, these data show that a short embryonic exposure to a neurotoxicant can alter development of neural synapses and lead to changes in adult behavior.

Threshold received sound pressure levels of single 1–2 kHz and 6–7 kHz up-sweeps and down-sweeps causing startle responses in a harbor porpoise (Phocoena phocoena)

Mid-frequency and low-frequency sonar systems produce frequency-modulated sweeps which may affect harbor porpoises. To study the effect of sweeps on behavioral responses (specifically "startle" responses, which we define as sudden changes in swimming speed and/or direction), a harbor porpoise in a large pool was exposed to three pairs of sweeps: a 1-2 kHz up-sweep was compared with a 2-1 kHz down-sweep, both with and without harmonics, and a 6-7 kHz up-sweep was compared with a 7-6 kHz down-sweep without harmonics. Sweeps were presented at five spatially averaged received levels (mRLs; 6 dB steps; identical for the up-sweep and down-sweep of each pair). During sweep presentation, startle responses were recorded. There was no difference in the mRLs causing startle responses for up-sweeps and down-sweeps within frequency pairs. For 1-2 kHz sweeps without harmonics, a 50% startle response rate occurred at mRLs of 133 dB re 1 μPa; for 1-2 kHz sweeps with strong harmonics at 99 dB re 1 μPa; for 6-7 kHz sweeps without harmonics at 101 dB re 1 μPa. Low-frequency (1-2 kHz) active naval sonar systems without harmonics can therefore operate at higher source levels than mid-frequency (6-7 kHz) active sonar systems without harmonics, with similar startle effects on porpoises.

Changes in wingstroke kinematics associated with a change in swimming speed in a pteropod mollusk,Clione limacina

In pteropod mollusks, the gastropod foot has evolved into two broad, wing-like structures that are rhythmically waved through the water for propulsion. The flexibility of the wings lends a tremendous range of motion, an advantage that could be exploited when changing locomotory speed. Here, we investigated the kinematic changes that take place during an increase in swimming speed in the pteropod mollusk Clione limacina. Clione demonstrates two distinct swim speeds: a nearly constant slow swimming behavior and a fast swimming behavior used for escape and hunting. The neural control of Clione's swimming is well documented, as are the neuromuscular changes that bring about Clione's fast swimming. This study examined the kinematics of this swimming behavior at the two speeds. High speed filming was used to obtain 3D data from individuals during both slow and fast swimming. Clione's swimming operates at a low Reynolds number, typically under 200. Within a given swimming speed, we found that wing kinematics are highly consistent from wingbeat to wingbeat, but differ between speeds. The transition to fast swimming sees a significant increase in wing velocity and angle of attack, and range of motion increases as the wings bend more during fast swimming. Clione likely uses a combination of drag-based and unsteady mechanisms for force production at both speeds. The neuromuscular control of Clione's speed change points to a two-gaited swimming behavior, and we consider the kinematic evidence for Clione's swim speeds being discrete gaits.

Behaviour of rainbow trout Oncorhynchus mykiss presented with a choice of normoxia and stepwise progressive hypoxia

The objective of this study was to identify behavioural adjustments leading to avoidance of hypoxia. Using the oxygen-sensitive species rainbow trout Oncorhynchus mykiss as a model, individual fish were recorded while moving freely between two sides of a test arena: one with normoxia and one with stepwise progressive hypoxia [80-30% dissolved oxygen (DO) air saturation]. The results demonstrated a gradual decrease in the total time spent in hypoxia starting at 80% DO air saturation. At this DO level, the avoidance of hypoxia could not be attributed to changes in spontaneous swimming speed, neither in normoxia nor in hypoxia. Reducing the DO level to 60% air saturation resulted in decreased spontaneous swimming speed in normoxia, yet the number of trips to the hypoxic side of the test arena remained unchanged. Moreover, data revealed increased average residence time per trip in normoxia at DO levels ≤60% air saturation and decreased average residence time per trip in hypoxia at DO levels ≤50% air saturation. Finally, the spontaneous swimming speed in hypoxia increased at DO levels ≤40% air saturation and the number of trips to hypoxia decreased at the 30% DO air saturation level. Thus, avoidance of the deepest hypoxia was connected with a reduced number of trips to hypoxia as well as decreased and increased spontaneous swimming speed in normoxia and hypoxia, respectively. Collectively, the data support the conclusions that the mechanistic basis for avoidance of hypoxia may (1) not involve changes in swimming speed during mild hypoxia and (2) depend on the severity of hypoxia.

A computer vision system to analyse the swimming behaviour of farmed fish in commercial aquaculture facilities: A case study using cage-held Atlantic salmon

Knowledge of fish behaviour plays an important role in aquaculture farm management. Video systems are the most common and cost-effective way of observing behaviours in commercial aquaculture operations. However long term observation is not feasible due to a limited ability to analyse footage manually. This paper describes preliminary findings obtained via computer vision software that was developed to automatically analyse fish movement and behaviours in aquaculture sea cages. Results show that the system is capable of detecting fish shapes in video recordings and from these shapes quantifying changes in swimming speed and direction continuously throughout the day. Also variations between days were detected and these may have been associated with the daily shift in the tidal cycle. The system has the potential to act as an alarm to farm operators, informing them about unusual fish behaviours on a continuous, real-time basis. It also has potential to assist in the evaluation of fish welfare.

Optimal stroke frequency during diving activity in seabirds

Diving animals have to counter both drag and buoyancy when moving through the water column. The magnitude of these forces depends upon an animal's swim speed and current depth. Feet, fins or flippers create a motivating force, and different stroke strategies give a variable level of output power, providing both fast swim speeds and reduced travel times to any given target depth. However, while feet, fins or flippers may confer a real advantage, they also create considerable drag and engen- der high metabolic (oxygen consumption) costs. Consequently, there should be an optimal relationship between output power and stroke frequency during diving. Here we develop diving models to predict the optimal pattern of stroke frequency during both the descent and ascent phase of divers in water, while maintaining a minimum cost of transport (COT, J kg -1 m -1 ). We also test predictions derived from these models using diving data for foot-propelled South Georgian shags Phalacrocorax georgianus diving to deeper than 80 m. Our predictions include: (1) output power (stroke frequency) should de- cline during the descent and ascent phases of a dive, but constant output power should be evident when the diving depth is shallow, (2) initial thrust for dives to deeper target depths should be smaller during the descent phase and greater during the ascent phase, and, (3) swim speed should be constant during the descent phase and should decrease first or remain constant, then increase during the ascent phase because of a declining output power strategy. Our empirical data on shags support only some of these predictions. Predictions (1) and (3) were supported by our observations, but Prediction (2) was not, possibly due to unknown but specific factors concerning diving seabirds. These findings suggest that diving seabirds adjust and control their stroke frequency pattern in order to minimize COT during diving, generating the observed changes in swimming speed.

Effects of vessels and swimmers on behavior of Hawaiian spinner dolphins (Stenella longirostris) in Kealake‘akua, Honaunau, and Kauhako bays, Hawai‘i

Studies of the influence of boat traffic on small cetaceans have shown that the animals exhibit behavioral responses, including changes in swimming speed, diving and aerial behavior, vocalization patterns, and movement patterns (e.g., Au and Perryman 1982; Janik and Thompson 1996, Constantine et al. 2004, Delfour 2007). Janik and Thompson (1996) cautioned that such disruptions could cause longer-term changes in behavior, ecology, or status of a population, including avoidance of certain areas or increases in mortality rates. In some cases, injury or death of dolphins (Stone and Yoshinaga 2000) and injury or death of humans (Shane et al. 1993, Santos 1997) have been reported. Recent studies have begun to discover dolphin avoidance of high-traffic areas (Lusseau 2004, 2005; Bejder et al. 2006a). Concerns have been raised about the effects of vessel and swimmer traffic on spinner dolphins (Stenella longirostris) resting in Hawaiian bays (Lammers 2004, Delfour 2007). Vessel and swimmer traffic in Kealake‘akua and other Hawaiian bays has increased (Ostman-Lind et al. 2004, Delfour 2007) since the original studies of Ken Norris and his colleagues (Norris and Dohl 1980; Norris et al. 1985, 1994). Spinner dolphins in the bays attract people, and dolphin disturbance as a result of increased swimmer and boat traffic needs to be assessed. Spinner dolphins use Hawaiian bays as havens in which to rest during the day (Norris et al. 1994), so disturbance by vessels and swimmers may affect their activity budgets and fitness. Concerns regarding dolphin disturbance have caused NOAA Fisheries to propose new regulations for interaction with Hawaiian spinner dolphins (Department of Commerce 2005, 2006). In response to these concerns, the purpose of our study was to document behavior of Hawaiian spinner dolphins in three bays with respect to vessel and swimmer traffic.

Complex Movements of Skipjack Schools Based on Sonar Observations during Pelagic Purse Seining

The movements of skipjack schools during purse seine operations were observed by scanning sonar in the Southwest Pacific Ocean in April 2004. Swimming speed and directional changes were analyzed in relation to heading of the purse seine during shooting, speed of the purse seiner and distance to the net. Escaped schools turned clockwise (relative to the heading of the purse seiner during shooting) significantly more frequently than captured schools, who primarily turned counter-clockwise. The swimming speed of a fish school, whether it was caught or escaped, was somewhat related to the ship's speed, but swimming speed did not differ between captured and escaped schools. The behavior of skipjack schools during purse seining consists of very complex movements with changes in swimming speed and direction in relation to the nets or purse seiner. Therefore, these responses of skipjack schools to purse seining can be useful for modeling the capture process of purse seining in relation to fishing conditions.

Vertical Migration and Motility Responses in Three Marine Phytoplankton Species Exposed to Solar Radiation†

Diurnal vertical migration in the water column and the impact of solar radiation on motility were investigated in three marine phytoplankton species: Tetraselmis suecica, Dunaliella salina and Gymnodinium chlorophorum. Cells were exposed to solar radiation either in ultraviolet radiation (UVR, 280-400 nm) transparent Plexiglas tubes (45 cm length, 10 cm diameter) or in quartz tubes under three radiation treatments: PAB (280-700 nm), PA (320-700 nm) and P (400-700 nm). The three species displayed different behavior after exposure to solar radiation. Tetraselmis suecica was insensitive to UVR and under high solar radiation levels, cells accumulated preferentially near the surface. Exposure experiments did not indicate any significant changes in swimming speed nor in the percentage of motile cells after 5 h of exposure. On the other hand, D. salina was sensitive to UV-B displaying a significant decrease in swimming speed and percentage of motile cells after 2-3 h of exposure. Moreover, D. salina cells migrated deep in the water column when irradiance was high. The response of G. chlorophorum was in between that of the other two species tested, with a slight (but significant) decrease in swimming speed and percentage of motile cells in all radiation treatments after 5 h of exposure. While G. chlorophorum cells were more or less homogenously distributed in the water column, a slight (but significant) avoidance response to high radiation was observed at local noon, with cells migrating deep in the water column. Our data clearly indicate that these sub-lethal effects of solar radiation are species-specific and they might have important implications for the aquatic ecosystem.

Swimming speed and foraging strategies of northern elephant seals

Abstract We investigated swimming speed, a key variable in both the management of oxygen stores and foraging strategies, and its relationship to diving behaviour in northern elephant seals , Mirounga angustirostris . Swimming speed significantly reduced the dive duration and time at depth for presumed foraging dives, but increased with dive depth. This suggests that the extended duration of deep dives is made possible by physiological adjustments and not by changes in swimming speed or effort. Swimming speeds were similar across sex and age classes despite different predicted minimum cost of transport speeds. All seals exhibited characteristic dive shapes and swimming speed patterns that support their putative functions, but two-dimensional dive shapes and swimming angles varied between sexes and age classes. Mean dive angles on descent were markedly shallow, suggesting use of negative buoyancy to cover horizontal distance while diving. Buoyancy also appeared to affect two-dimensional dive shapes and ability to use extended gliding behaviours between surface and deep foraging zones. Significant differences in diving behaviour between sexes and between young and adult females were evident for various phases of the dive cycle, potentially resulting from physical constraints or differences in dive functionality.

Dietary n-3 HUFA deficiency induces a reduced visual response in gilthead seabream Sparus aurata larvae

Developmental changes in swimming speed were analysed in the seabream ( Sparus aurata) larvae. Four feeding regimes using live preys (rotifer Brachionus plicatilis) enriched with fish oil, soybean oil, linseed oil and rapeseed oil, differing in fatty acid profile, were tested during the first weeks of larval life. There was an increase in burst swimming speed and cruise swimming speed during the visual stimulus experiment at day 16th of life in the present study in agreement with the better eye development in larvae of this age. Swimming activity before stimulus was significantly reduced when larvae were fed rotifers enriched with vegetable oils. Larvae fed with rotifers enriched with fish oil reacted with a higher burst swimming speed after a visual stimulus than after the sound stimulus (159.5 SL/s vs. 18.30 SL/s) denoting the importance of the vision during this period of development not only for predation but also for the burst. The reduction in dietary essential fatty acid contents, by the enrichment with vegetable oils, delays the appearance of response to visual stimulus, in agreement with the minor DHA content in eyes and brains of these larvae and suggesting a delay in the functional development of brain and vision.

Swimming Characteristics of the Black Porgy Acanthopagrus schlegeli in the Towing Cod-End of a Trawl

Fishing selectivity is determined by the level of voluntary escaping behavior in accordance with decision-making based on the relationship between fish size and mesh size. This study examined movement during the swimming behavior of black porgy in a trawl's towing cod-end and analyzed the movement components such as swimming speed, angular velocity of turning, and distance to the net over time. Most of the observed fish exhibited an optomotor response, maintaining position and swimming speed without changing direction. Others exhibited erratic or 'panic' behavior with sudden changes in swimming speed and direction. The latter behavior involved very irregular and aperiodic variations in swimming speed and angular velocity, termed 'chaotic behavior.' Thus, the results of this study can be applied to a chaotic behavior model as a time series of swimming movements in the towing cod-end for the fishing selectivity.

Response of copepods to physical gradients associated with structure in the ocean

We studied the response of the copepods Acartia tonsa and Temora longicornis to spatial gradients of flow velocity and fluid density to determine whether the presence of physical gradients initiated local search for resources or promoted aggregation. Two additional species of copepods, Candacia ethiopica and Labidocera madurae,were also exposed to velocity gradients. A plane jet flume apparatus facilitated the isolation of physical structures that mimic those found in the ocean and permitted high-resolution behavioral observations. All four species significantly increased the proportion of time in the gradient layer region relative to the total time in the observation window (proportional residence time) in response to the velocity-gradient layer. Behavioral changes, such as increased swimming speed and turn frequency, were consistent with area-restricted search behavior. T. longicornis also significantly increased proportional residence time in response to the density-gradient layer, but changes in swimming speed and turn frequency were not significantly different. A. tonsa and T. longicornis appeared to contact the density gradient and swim away or along the boundary. Hence, density gradients may act as a barrier to vertical movement and not as a positive cue for area-restricted search behavior. Velocity and density gradients play important, yet different, roles in defining patterns at fine-to-intermediate scales in zooplankton ecology.

The vertical component of a fish's spatial map

Fish orient by using a memorized map of their surroundings and, as they live in aquatic environments, this map must be three dimensional. Studies have shown that fish are able to encode horizontal information; however, we have little information about the cues that are learnt and remembered in the vertical axis. We used the blind Mexican cave fish, Astyanax fasciatus, to test whether fish can orient in the vertical axis and whether they use hydrostatic pressure to do so. After learning the cues associated with a specific height in the aquarium (evident by a reduction in swimming speed), the fish showed significant dishabituation (their swimming speed increased) when moved vertically upwards. When we controlled for the increase in light intensity from the bottom to the top of the tank the effect persisted, indicating that the most likely cue used by the fish to orient vertically was hydrostatic pressure. A post hoc experiment revealed that the change in swimming speed in response to altered light levels probably represents a change in the level of activity rather than an orientational response. This may define a photokinetic mechanism which operates in conjunction with a negatively phototactic response (revealed in previous experiments) by which the fish orient away from higher light levels and swim faster as light levels increase. This would result in the fish spending more time in lower light levels and would prevent the fish exiting the cave.

Behavior of larval Hemigrapsus sanguineus (de Haan) in response to gravity and pressure

Hemigrapsus sanguineus is an invasive species of crab (family: Grapsidae) in the north Atlantic basin. The species has spread rapidly since it was first discovered in North America in the late 1980s; however, the mechanisms of this range expansion remain unclear. This study attempts to predict the vertical distribution and, thus, ultimate transport of H. sanguineus larvae by examining larval responses to gravity and pressure. Geotaxis was determined by measuring the response of individual larvae to gravity in the absence of other tactic stimuli. Barokinesis was determined by measuring changes in swimming speed of larvae upon step-wise changes in pressure. Geotactic response of the larvae changes ontogenetically; early stage larvae are negatively geotactic (orienting towards the surface), while late stage larvae are positively geotactic (orienting towards the bottom). Larvae show a response to pressure that would aid in depth regulation. Early-stage larvae increase activity upon a change in pressure and orient their movement to gravity. However, the larvae show a relatively low sensitivity to pressure change. The evidence predicts an export-and-return model of larval transport, similar to that of Uca spp. in the Middle Atlantic Bight. This model supports the hypothesis that H. sanguineus larvae have the potential for high dispersal and will continue to invade new regions through larval transport.

Behavioral adaptations of the cubozoan medusa Tripedalia cystophora for feeding on copepod (Dioithona oculata) swarms

The cubozoan medusa Tripedalia cystophora preys on dense swarms of the copepod Dioithona oculata in the mangrove prop-root habitat of Puerto Rico. The copepod swarms form in shafts of sunlight that penetrate the mangrove canopy during the day. T. cystophora are found primarily within the same illuminated areas, feeding heavily on the dense swarms of copepods. Laboratory studies were conducted to examine the behavioral adaptations of T. cystophora that allow them to remain within these dense copepod swarms. In the presence of vertical light shafts, T. cystophora showed both a significant change in swimming speed and a significant increase in turning rate. T. cystophora turn abruptly when they leave a vertical shaft of light and quickly re-enter. The presence or absence of copepod prey, either in swarms or dispersed, had no significant effect on T. cystophora swimming speed or turning behavior. Feeding rates of T. cystophora on the copepod D. oculata increase rapidly with copepod density, and maximum rates are not achieved until the high densities associated with swarms are reached. It seems doubtful that these small medusae could survive without their ability to encounter and exploit these dense swarms of copepods.

Activity patterns of juvenile Atlantic cod (Gadus morhua) in Buckley Cove, Newfoundland

We monitored swimming speed of 2–3 year-old juvenile Atlantic cod (Gadus morhua) from August to December 1999, using a 2-D location finding acoustic telemetry system in a coastal area of Newfoundland, Canada. We concurrently monitored the locations of 22–41 individuals by triangulation using a fixed hydrophone array. We estimated average swimming speeds at intervals of 60–120 s and compared them over a 1 to 17 °C thermal range, three diel periods, and five substrates (sand, gravel, sand-sparse boulder, boulder, and kelp). However, cod did not exhibit a change in swimming speed over the temperature range studied. Increased activity and foraging rates (expressed as swimming speeds) were expected to increase at elevated temperatures due to increased metabolic demands. Activity did vary significantly with diel cycle and substrate. Swimming speeds were significantly lower at night during September and October. Results for August and November were inconclusive, while swimming speed was significantly lower during the day in December. We observed significantly reduced average swimming speeds in structurally complex substrates (e.g. rock, cobble and kelp) in September and October. Our results suggest that activity of juvenile cod in the wild does not vary with temperature as predicted from studies in the laboratory. Instead, activity varied with diel cycles and structural complexity, variables that influence an individual’s ability to forage and seek refuge, potentially altering individual fitness.

Caudal differential pressure as a predictor of swimming speed of cod (Gadus morhua).

We report the results of an experiment designed to investigate the feasibility of using differential pressure to estimate the swimming speed and metabolic rate of Atlantic cod (Gadus morhua). Seven cod were fitted with a miniature differential pressure sensor mounted on one side of the caudal peduncle immediately anterior to the base of the caudal fin rays. Relationships between differential pressure, tailbeat frequency, tailbeat amplitude, swimming speed and rate of oxygen consumption ((O(2))) were determined as a function of the swimming speed of cod swimming at 5 degrees C in a recirculating 'Brett-style' respirometer. Tailbeat differential pressure, tailbeat amplitude and tailbeat frequency were highly correlated with swimming speed. The average or integrated pressure ranged from 0 to 150 Pa for speeds up to 0.8 m s(-1) (1.1 L s(-1), where L is total body length), while the 'pressure difference' (maximum minus minimum pressure) ranged from 0 to 900 Pa. Small changes in swimming speed of less than 0.05 m s(-1) were readily detected as differences in tailbeat pressure. Burst swimming in the respirometer resulted in huge pressure 'bursts' of up to 5000 Pa 'pressure difference'. The rate of oxygen consumption increased exponentially and was highly correlated with swimming speed (r(2)=0.77). The rate of oxygen consumption was also correlated with tailbeat integrated pressure (r(2)=0.68) and with differential pressure (r(2)=0.43); regression correlations were always greater for individuals than for combined data from all cod. The results detailed in this study indicate that an ultrasonic differential pressure transmitter would enable accurate estimates of the swimming speed, rates of oxygen consumption and activity patterns of free-ranging fish in nature.