A seven-year record of fluctuating core body temperatures of nesting leatherback and hawksbill sea turtles

Sea turtles experience considerable changes in water temperatures during
migrations and seasonal movements that will influence their body
temperatures. Nothing is known of how sea turtles’ core body temperatures
vary from season to season at nesting sites. Over seven consecutive
seasons we measured the surface temperatures of freshly laid eggs as
proxies of core body temperatures of sea turtles using non-contact
infrared thermometers. We estimated the temperatures of two species that
have contrasting migration patterns - leatherbacks, which are adapted to
migrate between tropical breeding sites to cold temperate waters, and
hawksbills that are confined to the tropics and sub-tropics. We found
considerable year-to-year variations in temperatures in both species
(means ranging from 30.4°C to 31.5°C in leatherbacks), hawksbills the more
so (28.1°C to 30.3°C). These differences will likely be modified by both
natural seasonal variations and anthropogenic changes in global ocean
temperatures and resulting changes in currents and water temperatures
local to nesting beaches. These previously unrecognised fluctuations in
body temperatures of nesting turtles have, it is argued, potential for
predicting environmental tolerances, reproductive success, and nest site
selection by sea turtles, and contribute to predictions of which rookeries
may remain viable or not during future ocean warming.