as the cellular demand for protein synthesis and growth increases (Buckley et al. 1999), while

DNA content per cell should be relatively constant (Wallace 1992). The RNA:DNA ratio is

therefore an index of cellular protein synthesis capacity. Because nucleic acid concentrations and

the ratios between them respond rapidly to fluctuations in food availability, they are considered

reliable indices of instantaneous condition and growth (Rooker et al. 1997, Okumura et al. 2002,

Islam and Tanaka 2005, Vidal et al. 2006). Despite widespread use as sensitive measures of

recent growth rates in marine fish and invertebrates, nucleic acid ratios have not been validated

for application to studies of reptile growth.

 The purpose of this study was to evaluate the use of morphometric and biochemical indices

as predictors of recent growth rates in green turtles maintained under controlled feeding

conditions. Because analyzing biochemical indices of growth typically requires homogenization

of tissues extracted from euthanized individuals, I also examined the potential for measuring

nucleic acid concentrations in whole blood, a tissue that is not typically tested in studies of this

kind. Validation of a physiological growth index that can be assessed using minimally invasive

sampling techniques and without sacrificing the animals would substantially enhance our ability

to monitor short-term responses of green turtles to environmental perturbations.

 Materials and Methods

Animal Care

 A twelve-week feeding trial was conducted at the Cayman Turtle Farm in Grand Cayman,

British West Indies, in accordance with the policies of the Institutional Animal Care and Use

Committee at the University of Florida (permit #Z061). Details of the animal care aspects of this

study can be found in Chapter 2. Briefly, Chelonia mydas hatchlings were housed individually in

sea water in 68-liter tanks. Turtles were fed turtle pellets (Melick Aquafeed, Catawissa, PA)

twice daily.