PLASMA TOCOPHEROL, RETINAL, AND CAROTENOID CONCENTRATIONS IN FREE-RANGING HUMBOLDT PENGUINS (SPHENISCUS-HUMBOLDTI) IN CHILE

Plasma retinol and alpha-tocopherol concentrations were measured in he parinized blood samples collected from 51 free-ranging adult Humboldt penguins (Spheniscus humboldti) residing at two colonies off the Chile an coast. Thirty samples were collected in April 1992 from penguins in habiting the Ex-islote de los Pajaros Ninos in Algarrobo, Chile. In Se ptember 1992, 21 samples were collected from birds inhabiting Isla de Cachagua, Chile. Samples were assayed for retinol, retinyl palmitate, alpha-tocopherol, gamma-tocopherol, lutein, beta-cryptoxanthin, lycope ne, alpha-carotene, and beta-carotene. Retinol, alpha-tocopherol, and lutein were detected in all samples, while lycopene and gamma-tocopher ol were not detected in any. A significantly higher percentage of samp les had detectable levels of retinyl palmitate and alpha-carotene in A pril (P < 0.001); for beta-cryptoxanthin the percentage was higher in September (P < 0.001). Plasma concentrations of alpha-tocopherol and l utein were higher in September. Alpha-tocopherol concentrations were 1 ,877.1 +/- 99.0 (SEM) mu g/dl in April compared to 2,289 +/- 122.3 mu g/dl in September (P < 0.05); lutein concentrations were 4.16 +/- 0.43 mu g/dl in April vs. 10.68 +/- 1.02 mu g/dl in September (P < 0.001). Retinol concentrations were not significantly different (117 +/- 8.0 mu g/dl in April vs. 105.3 +/- 7.6 mu g/dl in September). Both physiol ogic 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. (C) 1996 Wiley-Liss, Inc.