Carrasco-Cárdenas Antonia, Barrios-Guzmán Carmen, Negrete Javier, Rogers Tracey L, Guerrero Alicia I
Centro de Investigación y Gestión de Recursos Naturales (CIGREN), Instituto de Biología, Facultad de Ciencias, Universidad de Valparaíso, Gran Bretaña 1111, Playa Ancha, Valparaíso, Chile.
Departamento Biología de Predadores Tope, Instituto Antártico Argentino, 25 de Mayo 1143, B1650CSP, San Martín, Buenos Aires, Argentina.
Sci Rep. 2025 Jul 2;15(1):23384. doi: 10.1038/s41598-025-07004-7.
Blubber stratification can significantly impact diet estimation, as using the inner or outer blubber layer may lead to different results depending on the degree of stratification present. We aimed to quantitatively evaluate the effect of blubber stratification on diet estimation at the population and individual levels in two species of phocid seals: the leopard seal (Hydrurga leptonyx) and the crabeater seal (Lobodon carcinophaga), using the mixing model MixSIAR. In leopard seals, krill contributed most significantly to the diet based on the inner layer (68.2%), while Antarctic silverfish dominated the outer layer (59.2%). For crabeater seals, krill was the primary prey in both layers, but with different contributions (87.1% inner layer vs. 63.4% outer layer). Both species exhibited greater individual specialization according to the outer layer compared to the inner layer, suggesting lower individual variability in the summer than in winter, when it may increase due to reduced prey availability. These findings have implications for trophic studies in marine mammals, as the sampling method may lead to contrasting diet estimates, altering prey contribution percentages and their relative dominance, in particular in generalist species. In specialists with low stratification, however, the need to obtain the inner blubber for accurate results is reduced.
鲸脂分层会显著影响饮食估计，因为根据存在的分层程度，使用内层或外层鲸脂可能会得出不同的结果。我们旨在使用混合模型MixSIAR，在种群和个体水平上定量评估鲸脂分层对两种海豹科海豹（豹海豹（Hydrurga leptonyx）和食蟹海豹（Lobodon carcinophaga））饮食估计的影响。在豹海豹中，基于内层的饮食中磷虾的贡献最为显著（68.2%），而南极银鱼在外层占主导地位（59.2%）。对于食蟹海豹，两层中的主要猎物都是磷虾，但贡献不同（内层为87.1%，外层为63.4%）。与内层相比，两种海豹根据外层表现出更大的个体专业化，这表明夏季个体变异性低于冬季，冬季由于猎物可获得性降低，个体变异性可能会增加。这些发现对海洋哺乳动物的营养研究具有启示意义，因为采样方法可能导致不同的饮食估计，改变猎物贡献百分比及其相对优势，特别是在食性广泛的物种中。然而，在分层程度低的特化物种中，获取内层鲸脂以获得准确结果的必要性降低。
