Marine Ecology Progress Series
MEPS is a leading hybrid research journal on all aspects of marine, coastal and estuarine ecology. Priority is given to outstanding research that advances our ecological understanding.
DOI: https://doi.org/10.3354/meps14885
copiedGravid green turtles employ a mixed capital–income breeding strategy where food is abundant
- Junichi Okuyama
- Narumi Kishida
- Hideaki Nishizawa
- Yuka Obe
- Takuro Mogi
- Takuya Koizumi
- Takuji Noda
- Tohya Yasuda
- Yuuki Kawabata
- Takashi Yokota
- Kotaro Ichikawa
- Yasushi Mitsunaga
- Nobuaki Arai
ABSTRACT: Sea turtles are marine ectotherms commonly considered capital breeders that use accumulated energy stores for reproduction. In some green turtle (Chelonia mydas) populations, there have been reports of feeding by gravid females during the inter-nesting period, indicating that they are not exclusively capital breeders but may supplement energy stores with energy gained through feeding during inter-nesting periods. However, the significance of this feeding remains unknown, as does the time allocation between energy intake and energy-saving behaviors during inter-nest periods. In this study, we deployed video, head-mounted acceleration, and GPS loggers on nine green turtles nesting on Ishigaki Island, Japan, to monitor their feeding behavior during the inter-nesting period. We found that the turtles spent nearly half of the inter-nesting period resting (42.1% on average), but also dedicated 3.4% of their time to foraging, exhibiting a bimodal daily pattern with peaks in activity during the early morning and evening. Most feeding occurred around the algae/seagrass meadows in close vicinity to resting sites, so little energy is required to shuttle between feeding and resting sites. In such cases, the energy stores acquired prior to the breeding migration can be “topped up” with feeding during inter-nest intervals. Our results indicate that gravid green turtles employ a mixed capital–income breeding strategy in which females mostly rely on capital-energy, but may supplement this with small amounts of income-energy gained by feeding during inter-nesting periods.
KEYWORDS
Junichi Okuyama (Corresponding Author)
- Fisheries Technology Institute, Japan Fisheries Research and Education Agency, Fukai Ota 148, Ishigaki, Okinawa 907-0451, Japan
Narumi Kishida (Co-author)
- Graduate School of Agriculture, Kindai University, Nakamachi 3327-204, Nara 631-8505, Japan
Hideaki Nishizawa (Co-author)
- Graduate School of Informatics, Kyoto University, Yoshida Honmachi, Sakyo, Kyoto, 606-8501, Japan
Yuka Obe (Co-author)
- Graduate School of Informatics, Kyoto University, Yoshida Honmachi, Sakyo, Kyoto, 606-8501, Japan
Takuro Mogi (Co-author)
- Graduate School of Agriculture, Kindai University, Nakamachi 3327-204, Nara 631-8505, Japan
Takuya Koizumi (Co-author)
- Graduate School of Informatics, Kyoto University, Yoshida Honmachi, Sakyo, Kyoto, 606-8501, Japan
Takuji Noda (Co-author)
- Graduate School of Informatics, Kyoto University, Yoshida Honmachi, Sakyo, Kyoto, 606-8501, Japan
Tohya Yasuda (Co-author)
- Graduate School of Informatics, Kyoto University, Yoshida Honmachi, Sakyo, Kyoto, 606-8501, Japan
Yuuki Kawabata (Co-author)
- Graduate School of Informatics, Kyoto University, Yoshida Honmachi, Sakyo, Kyoto, 606-8501, Japan
Takashi Yokota (Co-author)
- Graduate School of Informatics, Kyoto University, Yoshida Honmachi, Sakyo, Kyoto, 606-8501, Japan
Kotaro Ichikawa (Co-author)
- Graduate School of Informatics, Kyoto University, Yoshida Honmachi, Sakyo, Kyoto, 606-8501, Japan
Yasushi Mitsunaga (Co-author)
- Graduate School of Agriculture, Kindai University, Nakamachi 3327-204, Nara 631-8505, Japan
Nobuaki Arai (Co-author)
- Graduate School of Informatics, Kyoto University, Yoshida Honmachi, Sakyo, Kyoto, 606-8501, Japan
Handling Editor:
Graeme Hays, Burwood, Victoria, Australia
Reviewers:
S. Fossette and D. Booth, and previous version reviewed in MEPS by Y. Kaska and 2 anonymous