and DNA content of blood. Both of these parameters are easily quantified with minimal

disturbance to the animal, suggesting that biochemical indices hold promise as potential

indicators of recent growth in wild turtles.

 After demonstrating the substantial physiological and morphological plasticity of green

turtles exposed to different nutritional environments over short time scales, I became interested

in the long-term effects of food availability. A conspicuous feature of green turtle growth is the

transient nature of CG after a switch from restricted to ad libitum feeding. In addition, the

occurrence of CG indicates that "normal" growth rates in this species are sub-maximal,

suggesting that rapid growth may be associated with one or more costs (Metcalfe and Monaghan

2001). Mangel and Munch (2005) posited that these costs could include elevated levels of

oxidative damage incurred during CG. The results I presented in Chapter 4 provide the first

empirical evidence supporting this hypothesis. Although antioxidant function of muscle (a post-

mitotic tissue) was unaffected by diet, the activity of glutathione peroxidase (an antioxidant

enzyme) and total antioxidant potential per cell in the liver (a mitotically active tissue) were

approximately two-fold greater in continuously ad libitum-fed turtles than in continuously food-

restricted turtles or fast-growing turtles that had undergone growth compensation. An impaired

antioxidant defense system is therefore a cost of CG in green turtles. However, the duration of

this impairment is unknown, as are its life-history consequences.

 The long lifespan and large body size of green turtles were not conducive to evaluating

long-term responses to fluctuations in food availability. Instead, I took a novel approach by using

a parthenogenetic insect as my animal model for Chapter 5, and this tactic proved to be a fruitful

one for investigating questions about life history. In contrast to my work on C. mydas, I did not

find any evidence of CG in C. morosus. It is possible that an herbivorous diet precludes growth