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Dietary and reproductive biomarkers in a generalist apex predator reveal differences in nutritional ecology across life stages
Marine Ecology Progress Series ( IF 2.5 ) Pub Date : 2021-04-15 , DOI: 10.3354/meps13640
BS Rangel 1 , N Hammerschlag 2, 3 , JA Sulikowski 4 , RG Moreira 1
Affiliation  

ABSTRACT: Knowledge of the nutritional requirements of apex predators is key for determining ecological interactions. However, an understanding of how diet is influenced by reproduction, and the consequences of foraging variation on the nutritional status of a predator, is limited. Here, we used short-term dietary markers (plasma and whole-blood fatty acids) integrated with reproductive hormones (17β-estradiol and testosterone) and ultrasonography as a non-lethal approach to investigate the effect of life stage on nutritional status and trophic dynamics of female tiger sharks Galeocerdo cuvier. Despite their generalist feeding behavior, female tiger sharks fed on different food sources and/or modulated their fatty acid metabolism depending on the reproductive context. This suggests some adjustment in their nutritional requirements associated with changes in their reproductive state. Plasma and whole-blood fatty acids indicated distinct dietary sources across life stages, with a high dependence on coastal/benthic food resources during juvenile life stages, and on pelagic/oceanic and reef-associated food resources during adult life stages. Higher percentages of highly unsaturated omega-3 fatty acids found in females during their reproductive cycles suggest the dependency on these fatty acids as a source of metabolic energy during reproduction. A high percentage of arachidonic acid (ARA) found in plasma of gravid females suggests the possibility of a selective diet of ARA-rich prey species and/or selective mobilization of ARA from stored energy during gestation. Based on our findings, we propose a conceptual model of expected changes in nutritional and trophic markers across life stages of female tiger sharks.

中文翻译:

全能型捕食者中的饮食和生殖生物标志物揭示了生命各个阶段的营养生态学差异

摘要:认识到天敌捕食者的营养需求是决定生态相互作用的关键。但是,对饮食如何受生殖影响以及觅食变化对捕食者营养状况的影响的理解是有限的。在这里,我们将短期饮食标志物(血浆和全血脂肪酸)与生殖激素(17β-雌二醇和睾丸激素)和超声检查相结合,作为一种非致命方法来研究生命阶段对营养状况和营养动力学的影响虎鲨的图片Galeocerdo cuvier。尽管它们具有一般的摄食行为,但它们的雌性虎鲨以不同的食物为食,和/或根据生殖环境调节其脂肪酸的代谢。这表明与生殖状态变化有关的营养需求有所调整。血浆和全血脂肪酸表明整个生命阶段的饮食来源不同,在青少年生命阶段高度依赖沿海/底栖食物资源,在成年生命阶段高度依赖中上层/海洋和与珊瑚礁相关的食物资源。女性在生殖周期中发现的高度不饱和的omega-3脂肪酸百分比较高,表明对这些脂肪酸的依赖是生殖过程中代谢能量的来源。在妊娠女性血浆中发现高比例的花生四烯酸(ARA),表明有可能选择性饮食富含ARA的猎物和/或在妊娠期间从储存的能量中选择性地动员ARA。根据我们的发现,我们提出了整个雌性虎鲨生命阶段营养和营养标记预期变化的概念模型。
更新日期:2021-04-15
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