Abstract of Dissertation Presented to the Graduate School
 of the University of Florida in Partial Fulfillment of the
 Requirements for the Degree of Doctor of Philosophy

 PHYSIOLOGICAL AND LIFE-HISTORY RESPONSES TO PATTERNS OF
 FOOD AVAILABILITY

 By

 Alison M. Roark

 August 2007

Chair: Karen A. Bjorndal
Major: Zoology

 Green turtles (Chelonia mydas) experience nutritional stochasticity as oceanic-stage

juveniles and should therefore be capable of compensatory growth (CG) following periods of

nutritional stress. The purpose of the first phase of my research was to test for the occurrence of

CG in green turtles and determine its mechanismss. Food-restricted turtles (R) grew more

slowly, differed in cell size and body composition, and had proportionally smaller digestive

organs than turtles feeding ad libitum (AL). After food conditions improved, previously

food-restricted turtles (R-AL) demonstrated CG. This growth pattern was elicited by enhanced

food conversion efficiency rather than hyperphagia. The period of growth compensation may

have ended when R-AL turtles attained a body composition similar to that of AL turtles. These

findings indicate that growth rate, morphology, and body composition of juvenile green turtles

are plastic in response to diet and that individuals can compensate for environmental variability

to capitalize when conditions improve. However, CG was associated with altered antioxidant

function. Activity of glutathione peroxidase and total antioxidant potential per liver cell were

greater in AL turtles than in R and R-AL turtles, respectively, at the conclusion of the study.

Therefore, impaired antioxidant capacity may be a cost of rapid growth in this species.