Thesis (M.S.)--Ohio University, June, 2008. / Title from PDF t.p. Includes bibliographical references.

Thesis (doctoral)--James Cook University of North Queensland, 1997. / Bibliography: leaves 150-167.

Thesis (M.Sc.)--Acadia University, 2000. / Includes bibliographical references (leaves 66-71). Also available on the Internet via the World Wide Web.

The normal breathing pattern recorded in unanaesthetized, lightly re-strained turtles, Chrysemys picta, consisted of periods of continuous breathing interspersed with periods of breath holding. During each ventilatory period, respiratory frequency and tidal volume were controlled separately and independently of breath length, the total inspiratory interval, the active inspiratory interval and the expiratory interval. Increases in pulmonary minute ventilation during hypercapnia were caused by increases in respiratory frequency due solely to shortening of the intervals of breath holding. The frequency of breathing within each ventilatory period remained constant. There was a large variability in inspiratory and expiratory gas flow rates yet tidal volume was maintained within narrow limits by adjustment of the lengths of the active inspiratory and expiratory intervals. This mechanism was dependent upon lung volume information carried within the vagus nerve. Following vagotomy, changes in minute ventilation due to hypercapnia stemmed primarily from changes in tidal volume while changes in respiratory frequency were markedly reduced. Lung volume information carried within the vagus nerve arose from slowly adapting pulmonary stretch receptors. Single fibre nerve activity from pulmonary receptors was recorded from vagal slips in single-pithed tidally ventilated turtles. The major stimulus of these receptors was the change in lung volume throughout each breathing cycle. The rate and degree of change in transpulmonary pressure were without direct effect on receptor discharge. The functional characteristics of these receptors differed only quantitatively from those recorded in pulmonary stretch receptors of mammals and these differences probably stem from the lower body temperature of the turtle and the location of the receptors in the turtle lung. Most receptors were sensitive to CO₂, several sufficiently sensitive that both tonic and phasic receptor discharge were totally inhibited throughout the ventilatory cycle by 5 to 10% CO₂ in the inspired gas. Pulmonary mechanoreceptors in the frog were also shown to be sensitive to. The acute sensitivity to of a few receptors in turtles and frogs parallels that of the intrapulmonary receptors described-in birds and suggests that a pulmonary receptor with distinct mechano- and chemosensitive properties may represent the functional precursor of the variety of pulmonary receptor types which appear in modern day vertebrates. To examine the role of sensitivity of pulmonary receptors in the overall response of turtles to inhaled CO₂, ventilatory responses of unanaesthetized turtles to changes in the intrapulmonary CO₂ content of a vascularly isolated lung (constant PaCO₂ ) and an intact lung were measured during spontaneous breathing. The isocapnic hyperpnea associated with inhalation of CO₂ by the vascularly isolated lung was small and abolished by vagotomy. It is concluded that both inhibition of pulmonary stretch receptor discharge with increasing levels of FICO₂ and a functional increase in central inspiratory volume threshold contributed significantly to tidal volume increases during hypercapnia. The primary ventilatory response of intact turtles to increasing levels of FICO₂ was an increase in respiratory frequency and this response FICO₂ was greatly reduced when CO₂ was inspired only by the vascularly isolated lung. Thus the ventilatory response of turtles to increasing levels of FICO₂ is primarily dependent upon increased levels of arterial CO₂. The effect of vagotomy in producing apneusis in turtles supports suggestions they lack a pneumotaxic centre. The arrhythmic breathing pattern in turtles with intact vagal nerves, however, bears no similarity to the pattern of breathing in mammals with only the pneumotaxic centre ablated. It is concluded that the vagal input from pulmonary receptors to the respiratory centres in turtles is qualitatively similar to that in mammals yet the differences in central integration of lung volume information in turtles and mammals are not due solely to the absence of a pneumotaxic centre in the turtle. Many of the remaining differences may arise from the lower metabolic demand of turtles but how this affects central integration and respiratory pattern generation is unknown. / Science, Faculty of / Zoology, Department of / Graduate

In sea turtles, body condition can be evaluated through subjective body condition scoring (BCS), calculating body condition index (BCI), and clinical blood parameters. The goal of this study was to analyze ultrasonography of subcutaneous fat depth as a method to estimate body condition in 10 green and 8 loggerhead sea turtle carcasses using two types of portable ultrasound technologies, the Ibex Evo® and the Renco Lean-Meater®. Despite the general lack of significant correlations between ultrasound-assisted, gross, and histological measurements, the dorsal shoulder and lateral neck were determined to provide the most consistent images of subcutaneous fat. Florida live-captured green turtles were sampled and ultrasound-assisted fat depth measurements were taken at the dorsal shoulder region; however, there were no significant correlations found between fat depth and BCI or blood analytes (PCV, total protein). BCI reference quartiles were created using associations between BCI and BCS to help provide biological context to BCI data and allow for rapid categorization of sea turtle body condition. / Includes bibliography. / Thesis (MS)--Florida Atlantic University, 2021. / FAU Electronic Theses and Dissertations Collection

A group of red-eared turtles (Pseudemys scripta elegans) was acclimated to 18-20˚C and artificial photo-period for 21 days. The animals were then individually placed in a thermal gradient and their selected temperatures were continuously recorded for 24 hours. A second group of turtles was acclimatized to 7.5-11.0˚C and natural photoperiods for 28 days, and subsequently tested in the same manner as the first group. Lastly, the turtles in the first group, after being acclimated to 3.0˚C and the previous artificial photoperiod for 14 days, were retested in the gradient.

Variation in chelonian reproductive patterns is well documented. Previous studies of loggerhead musk turtles (Sternotherus minor) reproduction have not attempted to control for variation in latitude, local population differences, and seasonal variation. The present study attempts to control for these variables by collecting turtles from one population for one reproductive season. The reproductive pattern of S. minor at the southern limit of its range (Central Florida) is compared to those of S. minor studied elsewhere. Both male and female musk turtles mature after five to six years and at approximately 60mm plastron length. No sexual dimorphism in overall body size is evident. There is a significant relationship between testis mass and male body size. Spermatogenesis begins in June as testes begin to enlarge. A peak in the testicular cycle is observed in August and September followed by testicular regression from October through January. A germinal quiescent phase is evident from February through April. Vitellogenesis in females begins in mid-September and the first clutch is laid in late October. Ovipositions continue until mid-June when follicular regression begins. A brief but distinct ovarian quiescent period occurs in August. Mean clutch size is 3.0 (range= 1-5). Clutch size and clutch mass were significantly correlated with body size. Egg length is not significantly correlated with clutch size or plastron length. Four clutches per year are common and some females probably produce five. Reproductive potential and individual reproductive effort are both correlated with body size. Testicular activity peaks six months after a peak in the ovarian cycle. Similarities with other studies of Sternotherus minor include: timing of the reproductive cycles, mean female size, and size and age at maturity. Mean clutch size in Central Florida is significantly larger than elsewhere. This difference is explained by the fact that more females produce three and four eggs. While similarities and differences in reproductive characteristics do exist between Central Florida S. minor and more northern populations, it is clear that those similarities and differences must be interpreted with respect to the methods of data collection used. Annual reproductive potential is enhanced in the Central Florida population. This is explained by greater resource availability which is translated into a greater reproductive output.

The reproductive biology of the Florida east coast terrapin, Malalemys terrapin tequesta was studied during 1977-1978 at the Merritt Island National Wildlife Refuge, Brevard County, Florida. Mating occurred in small canals and ditches during late march and April. Terrapins exhibited a poorly developed courtship behavior system: this was attributed to the relative isolation of the species due to its brackish water habitat. Nesting occurred on dike roads, rather than on sand dunes as reported for other races of Malaclemys. Air temperature was the most important factor controlling nesting activity. One to three clutches were laid each year. Malaclemys appeared to exhibit a clinal variation in clutch size between northern and southern populations. Reduced clutch size in the south is explained by a relative increase in egg and hatchling size, possible resulting in greater survivorship of offspring in southern populations. Adult females nesting on dike roads are subject to severe predation from raccoons.

The seasonal and diel movements of fourteen immature green turtles (Chelonia mydas) in Mosquito, Lagoon, Florida were monitored using sonic telemetry. The feeding ecology of this turtle population was also studied using dissection and stomach flushing techniques. An attempt was made to relate the movement patterns of the turtles to their feeding habits. The immature green turtles were found to make seemingly random, long distance movements (X̄km moved/day=7.79) and to remain in deeper waters (X̄depth=1.63m), apparently not feeding, when water temperatures fell below 19°C. When average water temperatures ranged between 19-25°C, the turtles were found primarily in shallow waters (X̄depth=1.1m) and demonstrated a decrease in agility (X̄km moved/day=3.14). At water temperatures above 25°C, the animals became even less agile (2.58 km moved per day) and adopted a home range area that included a "center of activity" and a "home site." A "shuttling" behavior was observed when water temperatures averaged 31°C and higher. In the early mornings, turtles were found feeding on the grass flats. When shallow water temperatures rose above 30°C at midday, the turtles would relocate to deeper water. In late afternoon, they would return to the grass flats for a short period of time. Sea grasses made up 88% of the lagoonal turtle diet, with manatee grass (Syringodium filirorme) alone constituting 77%. No significant difference was found in per cent composition of stomach contents obtained in January via dissection and August via pumping.

Clutches of eggs wore collected from nesting loggerhead sea turtles (Caretta caretta caretta) on Merritt Island, Florida, during June - August 1977. Of these, 46 clutches were selected for experimentation to determine the extent to which certain factors affect hatching success. Twelve clutches were divided into subsamples which were incubated in sand maintained at 0, 25, 50, 75, and 100% moisture. Another twelve clutches were divided into subsamples and incubated in sand kept moist with the following percentages of seawater: 0 (distilled water), 25, 50, 75, and 100%; subsamples from four other clutches were subjected to the effects of one tidal inundation. Eggs from four of the clutches used in the moisture and salinity experiments were monitored for changes in size. Fifteen clutches were divided into subsamples which were kept in incubators maintained at 20, 24, 27, 30, 32, 35, and 38°C; subsamples from seven of these clutches were moved from unfavorable to optimal temperatures to study their ability to recover from stress. Three clutches were selected for an experiment to determine the effects of handling on hatching success; the following year, another five clutches were used for similar studies. Some of the hatchling turtles produced in this project were abnormal, and these were discussed in depth. From the experiments, it was determined that 25% moisture, 0-25% seawater, and 27°C produced the maximum percent hatch. The effects of handling on hatching success depended variably on the time and manner of handling. The optimum values indicated in the experiments closely approximated values for moisture, salinity, and temperature obtained from natural turtle nests on the beach.