Development Of Swimming Ability Research Articles

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

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

Swimming speeds of larval coral reef fishes: impacts on self-recruitment and dispersal

The dispersal of larvae during their time in the pelagic environment is critically important to our understanding of marine populations. Recent publications have highlighted the potential importance of larval behaviour in influencing dispersal patterns of larval reef fishes. However, it has not been clearly established if their abilities are of a magnitude comparable to the potential effects of oceanic processes and whether larval behaviour is sufficient to facilitate self-recruitment. This study presents new data on the swimming speed of late-stage larvae to determine how they can swim relative to oceanic currents. The families examined comprised the Acanthuridae, Siganidae, Lutjanidae, Lethrinidae, Pomacentridae, Chaetodontidae, Nemipteridae, Monacanthidae, Psuedochromidae, Pomacanthidae and Apogonidae. The late-stage larvae of all reef fish families examined were able to swim at speeds greater than the mean transport speeds reported around reefs in most locations. However, even the best-swimming reef fish families could not swim faster than the maximum current speeds reported. Based on new and previously published data it appears that the development of swimming ability can be described adequately (80% of variation explained) as a linear increase from zero at hatching to a species-specific maximum at settlement. Calculations based on this developmental pattern suggest that most reef fish families could substantially influence their dispersal patterns relative to ocean currents for over 50% of their larval phase. For all families examined, swimming behaviour could potentially affect dispersal patterns on a magnitude similar to the dispersing effect of oceanic currents. In addition, the swimming capabilities of several reef fish families have the potential to facilitate active self-recruitment in a range of reef systems.

Pre- and postnatal exposure to dieldrin: Persistent stimulatory and behavioral effects

Dieldrin was fed to two generations of albino rats at levels often found in the environment (0.35 μg/kg/day, orally). A two-by-two factorial design was employed to investigate the simultaneous effect of a malnutrition condition consisting of low protein and dieldrin exposure. Second generation animals were tested using comprehensive behavioral criteria (swimming ability, righting reflex, motivational test, and a series of learning tasks) in order to detect any subtle diffeences between groups. Significant differences were seen between all of the test groups in the development of swimming ability. Animals in the 10% protein plus dieldrin (10% + D) were significantly inferior to the 10% protein group. However, rats in the 20% protein plus dieldrin (20% + D) were superior to all of the other groups in overall swimming ability. Both dieldrin groups were significantly superior to their control groups in the retention test (running the animals on the same problem 48 hr later), thus suggesting a stimulatory effect of low-dose dieldrin. No implication is made to suggest that the stimulatory effect is not harmful, since the consequences of such effects have not been determined by long-term studies.

Effect of thyroxine and cortisol on brain ornithine decarboxylase activity and swimming behavior in developing rat

Thyroxine and cortisol were tested to determine their effects on the ontogenetic pattern of ornithine decarboxylase (ODC) (EC 4.1.1.17) activity in rat brain. The effects of both hormones were significant, but varied with the brain region studied and with the age of the rat. Thyroxine (1 μg/g body wt/day injected i.p. × 3) altered ODC activity in all brain regions studied, if given during the first 10 postnatal days The overall effect was to compress the time course in which ODC activity passed through its ontogenetic pattern; both the peak in activity and the drop to the characteristic low adult activity level occurred earlier and were accelerated. The magnitude of the response to thyroxine was greater in the cerebellum, followed by the cerebrum and brainstem respectively. Cortisol, when given on the first postnatal day (0.5 mg i.p. × 1), initially depressed ODC activity and subsequently prolonged the time required to reach the low level of activity found normally in adult brain. The magnitude of the response to cortisol generally was greater than that of thyroxine, except in the cerebellum. The effects of these hormones on the ontogenetic pattern of ODC activity are consistent with previously observed effects in rats both on biochemical parameters, e.g. polyamine content and nucleic acid synthesis, and behavioral parameters, e.g. development of swimming ability. Our data are consistent with the hypothesis that thyroxine and cortisol, when administered to the neonate, may exert some of their effects on nucleic acid metabolism and ultimately growth, development and behaviour via their effects on polyamine metabolism.

Effects of early malnutrition on the development of swimming ability in the rat

The ontogeny of swimming ability was studied in normally fed and in chronically starved rats to assess the effect of early malnutrition on CNS development. Swimming tests were performed on adult and infant rats from 4–30 days old in an aquarium. Scoring according to position of the nose and movement of front legs. Maturation of swimming performance was delayed 2–3 days in the chronically starved rats as compared to controls. The high sensitivity of nervous tissue during critical periods of maturation and the relationship between malnutrition and the development of some patterns of movement during swimming are considered.