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Marine Ecology Progress Series

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MEPS 542:209-219 (2016)  -  DOI:

Green turtle Chelonia mydas foraging ecology at 25°S in the western Atlantic: evidence to support a feeding model driven by intrinsic and extrinsic variability

Luciana R. Gama1,2, Camila Domit1,*, Matt K. Broadhurst3,4, Mariana M. P. B. Fuentes5, Russell B. Millar6

1Laboratório de Ecologia e Conservação, Centro de Estudos do Mar, Universidade Federal do Paraná, Av. Beira Mar s/n, 83255-000, Pontal do Sul, Paraná, Brazil
2Programa de pós-graduação em Biologia, Universidade Estadual de Londrina, Londrina, Paraná, Brazil
3New South Wales Department of Primary Industries, Fisheries Conservation Technology Unit, PO Box 4321, Coffs Harbour, New South Wales 2450, Australia
4Marine and Estuarine Ecology Unit, School of Biological Sciences, University of Queensland, Brisbane, Queensland 4072, Australia
5Department of Earth, Ocean and Atmospheric Science, Florida State University, Tallahassee, Florida 32306, USA
6Department of Statistics, The University of Auckland, Private Bag 92019, Auckland 1010, New Zealand
*Corresponding author:

ABSTRACT: Long-term temporal variation in juvenile Chelonia mydas foraging ecology and key intrinsic/extrinsic explanatory factors were assessed at the southwestern Atlantic tropical-temperate transition zone. During a 7 yr period, 120 stranded C. mydas (30 to 62 cm curved carapace length; CCL) were collected from beaches in Paraná, adjacent to the World Heritage listed Paranaguá estuarine complex (PEC). The digestive tracts of these specimens were excised and evaluated for dietary contents and morphology. A total of 12 items/groups were found, but mainly comprised Ulva sp. (43% of specimens), Sargassum sp. (28%), Halodule wrightii (26%), Avicennia schaueriana (26%), Gracilaria domingensis (22%), unidentified angiosperms (21%) and cephalopod beaks (8%). Nearly 70% of all C. mydas had ingested marine debris. Proportionally more items occurred in the stomach, followed by the intestines and oesophagus. Canonical analysis of principal coordinates revealed several trends, including a negative relationship between CCL and cephalopod consumption, and strong short- and long-term temporal associations with different herbivorous foods. The latter manifested as (1) more H. wrightii consumed during the wet season, and other species (but especially A. schaueriana and Sargassum sp.) during the dry; and (2) a diet change between 2008-2010 and 2012-2014, with a shift towards Ulva sp. in the latter period (particularly in 2013). The observed extrinsic variation was attributed to environmental perturbations associated with El Niño, and anthropogenic impacts associated with dredging that started in 2010 in the PEC and which affected foraging habitats. The results reaffirm the foraging variability of C. mydas, but also demonstrate that sufficient time-series data are required to adequately describe the ecology of the species as a precursor to management actions that conserve regional populations.

KEY WORDS: Brazil · Chelonia mydas · Conservation · Diet · Foraging · Life history

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Cite this article as: Gama LR, Domit C, Broadhurst MK, Fuentes MMPB, Millar RB (2016) Green turtle Chelonia mydas foraging ecology at 25°S in the western Atlantic: evidence to support a feeding model driven by intrinsic and extrinsic variability. Mar Ecol Prog Ser 542:209-219.

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