DOI: 10.5061/dryad.67g5d
title: Data from: Energy expenditure of adult green turtles (Chelonia mydas) at their foraging grounds and during simulated oceanic migration

description: Measuring the energy requirements of animals under natural conditions and
 determining how acquired energy is allocated to specific activities is a
 central theme in ecophysiology. Turtle reproductive output is
 fundamentally linked with their energy balance so a detailed understanding
 of marine turtle energy requirements during the different phases of their
 life cycle at sea is essential for their conservation. We used the
 non-invasive accelerometry technique to investigate the activity patterns
 and energy expenditure (EE) of adult green turtles (Chelonia mydas)
 foraging year-round at a seagrass meadow in Mayotte (n = 13) and during
 simulated oceanic migration (displacement from the nesting beach) off
 Mohéli (n = 1), in the south-western Indian Ocean. At the foraging site,
 turtles divided their days between foraging benthically on the shallow
 seagrass meadow during daylight hours and resting at greater depth on the
 inner side of the reef slope at night. Estimated oxygen consumption rates
 (sinline image) and daily energy expenditures (DEE) at the foraging site
 were low (sinline image during the day was 1·6 and 1·9 times the
 respective resting rate at night during the austral summer and winter,
 respectively), which is consistent with the requirement to build up
 substantial energy reserves at the foraging site, to sustain the
 energy-demanding breeding migration and reproduction. Dive duration (but
 not dive depth) at the foraging site shifted significantly with season
 (dive duration increased with declining water temperatures, Tw), while
 overall activity levels remained unchanged. In parallel with a significant
 seasonal decline in Tw (from 28·9 ± 0·1 °C to 25·3 ± 0·4 °C), there was a
 moderate (˜19%) but significant decline in DEE of turtles during the
 austral winter (901 ± 111 kJ day−1), when compared with the austral summer
 (1117 ± 66 kJ day−1). By contrast, the turtle moved continuously during
 simulated oceanic migration, conducting short/shallow dives in the day,
 which (predominately at night) were interspersed with longer and deeper
 ‘pelagic’ dives. Estimated oxygen consumption rates during a simulated
 migration (1·25 ± 0·16 mL O2 min−1 kg−0·83) were found to be significantly
 increased over the foraging condition, equal to ˜3 times the resting rate
 at night (0·42 ± 0·02 mL O2 min−1 kg−0·83), and daily energy expenditure
 amounted to 2327 ± 292 kJ day−1, underlining the tremendous energetic
 effort associated with breeding migration. Our study indicates that the
 accelerometry technique provides a new and promising opportunity to study
 marine turtle energy relations in great detail and under natural
 conditions.
description: upload for
 DryadThe zip files contains a
 WORD file that explains all contents of the uploaded data. There are two
 sub-directories ('analysis' and 'recorded files'),
 which contain the originally recorded files and the files created during
 analysis, respectively. All details about these files are provided within
 the WORD file ('Files uploaded to Dryad').