Data from: Regime shifts shorten food chains for mesopredators with potential sublethal effects

Dryad dataset consists of morphological, stable isotope, gut content and lipid data for Cephalopholis argus collected in the Seychelles Inner Island group.Abstract [Related Publication]: 1. Predator populations are in decline globally. Exploitation, as well as habitat degradation and associated changes in prey availability are key drivers of this process of trophic downgrading. In the short term, longevity and dietary adaptability of large-bodied consumers can mask potential sub-lethal effects of a changing prey base, producing a delayed effect that may be difficult to detect.2. In coral reef ecosystems, regime shifts from coral- to algae-dominated states caused by coral bleaching significantly alter the assemblage of small-bodied reef fish associated with a reef. The effects of this changing prey community on reef-associated mesopredators remains poorly understood.3. This study found that the total diversity, abundance and biomass of piscivorous mesopredators was lower on regime-shifted reefs than recovering reefs, 16 years after the 1998 mass coral bleaching event.4. We used stable isotope analyses to test for habitat-driven changes in the trophic niche occupied by a key piscivorous fishery target species on reefs that had regime-shifted or recovered following climatic disturbance. Using morphometric indices, histology, and lipid analyses, we also investigated whether there were sub-lethal costs for fish on regime-shifted reefs.5. Stable isotopes demonstrated that fish from regime-shifted reefs fed further down the food chain, compared to recovering reefs. Lower densities of hepatocyte vacuoles in fish from regime-shifted reefs, and reduced lipid concentrations in spawning females from these reefs, indicated a reduction in energy stores, constituting a sub-lethal and potential delayed effect on populations.6. Reduced energy reserves in mesopredators could lead to energy allocation trade-offs, and decreased growth rates, fecundity, and survivorship, resulting in potential population declines in the longer term.The full methodology is available in the publication shown in the Related Publications link below.

Dryad数据集（Dryad）收录了在塞舌尔内群岛采集的青星九棘鲈（Cephalopholis argus）的形态学、稳定同位素、胃含物及脂质数据。

摘要【关联出版物】：
1. 全球捕食者种群均呈下降趋势，过度捕捞、栖息地退化以及与之相关的猎物可获得性变化，是引发营养级退化这一过程的核心驱动因素。从短期来看，大型消费者的寿命与饮食适应性能够掩盖猎物基础变化所带来的潜在亚致死效应，进而产生难以被及时察觉的延迟影响。
2. 在珊瑚礁生态系统中，由珊瑚白化引发的珊瑚主导态向藻类主导态的稳态转换，会显著改变礁体相关小型礁鱼的群落组成，而这种猎物群落变化对礁栖中型捕食者的影响目前仍有待深入研究。
3. 本研究发现，在1998年大规模珊瑚白化事件发生16年后，发生稳态转换的礁体上，肉食性中型捕食者的总物种多样性、种群丰度与生物量均低于恢复中的礁体。
4. 本研究通过稳定同位素分析，探究了气候扰动后发生稳态转换或已恢复的礁体上，作为重要渔业目标物种的肉食性鱼类所占据的营养生态位是否因栖息地差异发生变化；同时借助形态学指标、组织学分析与脂质分析，调查了稳态转换礁体上的鱼类是否存在亚致死生存成本。
5. 稳定同位素分析结果显示，与恢复中的礁体相比，稳态转换礁体上的青星九棘鲈所处的营养级更低。此外，稳态转换礁体上的鱼类肝细胞空泡密度更低，且该礁体上产卵雌鱼的脂质浓度显著下降，这均提示其能量储备减少，意味着种群正面临亚致死且潜在的延迟性影响。
6. 中型捕食者的能量储备不足可能引发能量分配权衡，进而导致生长速率、繁殖力与存活率下降，最终在长期内造成种群潜在的衰退。

完整的研究方法可参阅下方关联出版物链接中的文献。