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

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 monito...

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Main Authors: Hart, KM, White, CF, Iverson, AR, Whitney, N
Format: Article
Language:English
Published: Inter-Research 2016-09-01
Series:Endangered Species Research
Online Access:https://www.int-res.com/abstracts/esr/v31/p61-73/
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spelling doaj-77fbeebdcb494b24a5b0b4bdd9ad17852020-11-25T02:10:13ZengInter-ResearchEndangered Species Research1863-54071613-47962016-09-0131617310.3354/esr00750Trading shallow safety for deep sleep: juvenile green turtles select deeper resting sites as they growHart, KMWhite, CFIverson, ARWhitney, NTo 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 <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.https://www.int-res.com/abstracts/esr/v31/p61-73/
collection DOAJ
language English
format Article
sources DOAJ
author Hart, KM
White, CF
Iverson, AR
Whitney, N
spellingShingle Hart, KM
White, CF
Iverson, AR
Whitney, N
Trading shallow safety for deep sleep: juvenile green turtles select deeper resting sites as they grow
Endangered Species Research
author_facet Hart, KM
White, CF
Iverson, AR
Whitney, N
author_sort Hart, KM
title Trading shallow safety for deep sleep: juvenile green turtles select deeper resting sites as they grow
title_short Trading shallow safety for deep sleep: juvenile green turtles select deeper resting sites as they grow
title_full Trading shallow safety for deep sleep: juvenile green turtles select deeper resting sites as they grow
title_fullStr Trading shallow safety for deep sleep: juvenile green turtles select deeper resting sites as they grow
title_full_unstemmed Trading shallow safety for deep sleep: juvenile green turtles select deeper resting sites as they grow
title_sort trading shallow safety for deep sleep: juvenile green turtles select deeper resting sites as they grow
publisher Inter-Research
series Endangered Species Research
issn 1863-5407
1613-4796
publishDate 2016-09-01
description 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 <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.
url https://www.int-res.com/abstracts/esr/v31/p61-73/
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