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A global review of green turtle diet: sea surface temperature as a potential driver of omnivory levels

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Version 2 2024-06-04, 14:03
Version 1 2020-11-26, 20:57
journal contribution
posted on 2024-06-04, 14:03 authored by N Esteban, JA Mortimer, HJ Stokes, JO Laloë, RKF Unsworth, Graeme HaysGraeme Hays
AbstractTo better understand dietary requirements, trophic shifts, and trophic interactions of the threatened green turtle (Chelonia mydas), we conducted a comprehensive global review and literature tabulation (177 studies) reporting diets of individuals > 25 cm carapace length. We analysed those studies involving natural sites and healthy animals that reported relative proportions of all diet components (67 studies, 89 datasets at 75 sites, 13 geographic sub-regions, 3 oceans). We compared diets by sub-region and foraging site relative to four diet components, i.e., seagrass, macroalgae, terrestrial plants (including mangroves) and animal matter. To assess sea surface temperature (SST) as an environmental driver, values were extracted from satellite data (single year) and site-specific observations (study durations) and examined relative to diet composition. Satellite data indicated that at warmer sites with temperatures > 25 °C (≥ 6 months annually), diet was predominantly herbivorous (mean = 92.97%; SE = 9.85; n = 69 datasets). At higher latitude sites and in cold-water currents with SST < 20 °C (≥ 6 months annually), dietary animal matter featured prominently (mean = 51.47%; SE = 4.84; n = 20 datasets). Site-specific observations indicated that SST had a small but significant effect on contributions of animal matter (r2 = 0.17, P =  < 0.001) and seagrass (r2 = 0.24, P =  < 0.001) but not macroalgae and terrestrial plants. Our study presents the first quantitative evidence at a global scale that temperature may be an important driver of omnivory, providing a new perspective on variations in green turtle diet, especially in light of global warming and climate change.

History

Journal

Marine Biology

Volume

167

Article number

ARTN 183

Pagination

1 - 17

Location

Cham, Switzerland

Open access

  • Yes

ISSN

0025-3162

eISSN

1432-1793

Language

English

Publication classification

C Journal article, C1 Refereed article in a scholarly journal

Issue

12

Publisher

SPRINGER HEIDELBERG