D.R. Thompson, S. Waldron and R.W. Furness. The trophic status of marine turtles as determined by stable isotope analysis. Isotope ratios in proteins from loggerhead turtles indicate that this species occupies a higher trophic position than green turtles.
Leatherback turtles are apparently intermediate in trophic status.
Within loggerhead turtles, both isotope ratios correlated positively with body size, indicating a trend of increasing trophic level with age. Within the size range of green turtles sampled, there was apparently no change in trophic level in relation to body size. In absolute terms, isotope signatures of egg proteins were markedly different from those of bone collagen. However, interspecific differences in isotope values were consistent with those in bone protein. The novel application of this technique to marine turtles generally confirmed dietary information collected conventionally in these species, and has also afforded additional insights into shifts in diet and trophic status as turtles mature.