Trading shallow safety for deep sleep: Juvenile green turtles select deeper resting sites as they grow

Endangered Species Research
By: , and 

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Abstract

To better protect endangered green sea turtles Chelonia mydas, a more thorough understanding of the behaviors of each life stage is needed. Although dive profile analyses obtained using time-depth loggers have provided some insights into habitat use, recent work has shown that more fine-scale monitoring of body movements is needed to elucidate physical activity patterns. We monitored 11 juvenile green sea turtles with tri-axial acceleration data loggers in their foraging grounds in Dry Tortugas National Park, Florida, USA, for periods ranging from 43 to 118 h (mean ± SD: 72.8 ± 27.3 h). Approximately half of the individuals (n = 5) remained in shallow (overall mean depth less than 2 m) water throughout the experiment, whereas the remaining individuals (n = 6) made excursions to deeper (4 to 27 m) waters, often at night. Despite these differences in depth use, acceleration data revealed a consistent pattern of diurnal activity and nocturnal resting in most individuals. Nocturnal depth differences thus do not appear to represent differences in behavior, but rather different strategies to achieve the same behavior: rest. We calculated overall dynamic body acceleration (ODBA) to assess the relative energetic cost of each behavioral strategy in an attempt to explain the differences between them. Animals in deeper water experienced longer resting dives, more time resting per hour, and lower mean hourly ODBA. These results suggest that resting in deeper water provides energetic benefits that outweigh the costs of transiting to deep water and a potential increased risk of predation.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Trading shallow safety for deep sleep: Juvenile green turtles select deeper resting sites as they grow
Series title Endangered Species Research
DOI 10.3354/esr00750
Volume 31
Year Published 2016
Language English
Publisher Inter-Research
Contributing office(s) Wetland and Aquatic Research Center
Description 13 p.
First page 61
Last page 73
Country United States
State Florida
Other Geospatial Dry Tortugas National Park
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