Plasma tocopherol, retinol, and carotenoid concentrations in free-ranging Humboldt penguins (Spheniscus humboldti) in Chile

Plasma retinol and α‐tocopherol concentrations were measured in heparinized blood samples collected from 51 free‐ranging adult Humboldt penguins (Sphenicus humboldti) residing at two colonies off the Chilean coast. Thirty samples were collected in April 1992 from penguins inhabiting the Ex‐islote de los Pájaros Niños in Algarrobo, Chile. In September 1992, 21 samples were collected from birds inhabiting Isla de Cachagua, Chile. Samples were assayed for retinol, retinyl palmitate, α‐tocopherol, γ‐tocopherol, lutein, β‐cryptoxanthin, lycopene, α‐carotene, and β‐carotene. Retinol, α‐tocopherol, and lutein were detected in all samples, while lycopene and γ‐tocopherol were not detected in any. A significantly higher percentage of samples had detectable levels of retinyl palmitate and α‐carotene in April (P < 0.001): for β‐cryptoxanthin the percentage was higher in September (P < 0.001). Plasma concentrations of α‐tocopherol and lutein were higher in September. Alpha‐tocopherol concentrations were 1,877.1 ± 99.0 (SEM) μg/dl in April compared to 2.289 ± 122.3 μg/dl in September (P < 0.05); lutein concentrations were 4.16 ± 0.43 μg/dl in April vs. 10.68 ± 1.02 μg/dl in September (P < 0.001). Retinol concentrations were not significantly different (117 ± 8.0 μg/dl in April vs. 105.3 ± 7.6 μg/dl in September). Both physiologic changes associated with season, and the change in locale may have contributed to the differences seen in the assay means and the number of samples with detectable levels. © 1996 Wiley‐Liss, Inc.