Diet of whale sharks Rhincodon typus inferred from stomach content and signature fatty acid analyses

Abstract

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 493:219-235 (2013) - DOI: https://doi.org/10.3354/meps10500 Diet of whale sharks Rhincodon typus inferred from stomach content and signature fatty acid analyses Christoph A. Rohner1,2,3,*, Lydie I. E. Couturier1,4, Anthony J. Richardson1,5, Simon J. Pierce3,6, Clare E. M. Prebble3, Mark J. Gibbons7, Peter D. Nichols8 1Climate Adaptation Flagship, CSIRO Marine and Atmospheric Research, EcoScience Precinct, GPO Box 2583, Brisbane, Queensland 4102, Australia 2Biophysical Oceanography Group, School of Geography, Planning and Environmental Management, The University of Queensland, St Lucia, Queensland 4072, Australia 3Manta Ray and Whale Shark Research Centre, Marine Megafauna Foundation, Praia do Tofo, Inhambane, Mozambique 4School of Biomedical Sciences, The University of Queensland, St Lucia, Queensland 4072, Australia 5Centre for Applications in Natural Resource Mathematics (CARM), School of Mathematics and Physics, The University of Queensland, St Lucia, Queensland 4072, Australia 6Wild Me, Praia do Tofo, Inhambane, Mozambique 7Department of Biodiversity & Conservation Biology, University of the Western Cape, Bellville 7535, South Africa 8Wealth from Oceans Flagship, CSIRO Marine and Atmospheric Research, GPO Box 1538, Hobart, Tasmania 7000, Australia *Email: c.rohner1@uq.edu.au ABSTRACT: Whale sharks Rhincodon typus are large filter-feeders that are frequently observed feeding in surface zooplankton patches at their tropical and subtropical coastal aggregation sites. Using signature fatty acid (FA) analyses from their subdermal connective tissue and stomach content analysis, we tested whether whale sharks in Mozambique and South Africa predominantly feed on these prey and/or what other prey they target. Arachidonic acid (20:4ω6; mean ± SD = 17.8 ± 2.0% of total FA), 18:0 and 18:1ω9c were major FA of whale sharks, while in contrast, coastal epipelagic zooplankton collected near feeding whale sharks had 22:6ω3 (docosahexaenoic acid), 16:0 and 20:5ω3 (eicosapentaenoic acid) as major FA. Stomach contents of 3 stranded sharks were dominated by mysids (61 to 92% of prey items), another one by sergestids (56%), and a fifth stomach was empty. The dominant mysids (82% index of relative importance) were demersal zooplankton that migrate into the water column at night, suggesting night-time feeding by whale sharks. High levels of bacterial FA in whale sharks (5.3 ± 1.4% TFA), indicating a detrital link, potentially via demersal zooplankton, also support night-time foraging activity. High levels of oleic acid (16.0 ± 2.5%) in whale sharks and their similarity with FA profiles of shrimp, mysids, copepods and myctophid fishes from the meso- and bathypelagic zone suggest that whale sharks also forage in deep-water. Our findings suggest that, in the patchy food environment of tropical systems, whale sharks forage in coastal waters during the day and night, and in oceanic waters on deep-water zooplankton and fishes during their long-distance movements. KEY WORDS: Feeding ecology · Omega 6 fatty acids · Signature lipids · Mysida · Chondrichthyans · Fatty acid biomarkers Full text in pdf format PreviousNextCite this article as: Rohner CA, Couturier LIE, Richardson AJ, Pierce SJ, Prebble CEM, Gibbons MJ, Nichols PD (2013) Diet of whale sharks Rhincodon typus inferred from stomach content and signature fatty acid analyses. Mar Ecol Prog Ser 493:219-235. https://doi.org/10.3354/meps10500 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 493. Online publication date: November 20, 2013 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2013 Inter-Research.