MEPS 455:245-256 (2012)  -  doi:10.3354/meps09674

Fatty acids and stable isotopes as indicators of early-life feeding and potential maternal resource dependency in the bull shark Carcharhinus leucas 

Laura L. Belicka1,3,*, Philip Matich2,3, Rudolf Jaffé1,3, Michael R. Heithaus2,3

1Southeast Environmental Research Center and Department of Chemistry and Biochemistry, and 2Department of Biological Sciences, Florida International University, Miami, Florida 33199, USA
3Marine Sciences Program, Florida International University, North Miami, Florida 33181, USA

ABSTRACT: The degree of reliance of newborn sharks on energy reserves from maternal resource allocation and the timescales over which these animals develop foraging skills are critical factors towards understanding the ecological role of top predators in marine ecosystems. We used muscle tissue stable carbon isotopic composition and fatty acid analysis of bull sharks Carcharhinus leucas to investigate early-life feeding ecology in conjunction with maternal resource dependency. Values of δ13C of some young-of-the-year sharks were highly enriched, reflecting inputs from the marine-based diet and foraging locations of their mothers. This group of sharks also contained high levels of the 20:3ω9 fatty acid, which accumulates during periods of essential fatty acid deficiency, suggesting inadequate or undeveloped foraging skills and possible reliance on maternal provisioning. A loss of maternal signal in δ13C values occurred at a length of approximately 100 cm, with muscle tissue δ13C values reflecting a transition from more freshwater/estuarine-based diets to marine-based diets with increasing length. Similarly, fatty acids from sharks >100 cm indicated no signs of essential fatty acid deficiency, implying adequate foraging. By combining stable carbon isotopes and fatty acids, our results provided important constraints on the timing of the loss of maternal isotopic signal and the development of foraging skills in relation to shark size and imply that molecular markers such as fatty acids are useful for the determination of maternal resource dependency.


KEY WORDS: Essential fatty acid deficiency · Fatty acids · Food webs · Maternal investment · Stable isotopes · Sharks


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Cite this article as: Belicka LL, Matich P, Jaffé R, Heithaus MR (2012) Fatty acids and stable isotopes as indicators of early-life feeding and potential maternal resource dependency in the bull shark Carcharhinus leucas . Mar Ecol Prog Ser 455:245-256

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