Evaluación de la potencial segregación por el forrajeo entre las colonias de la fardela blanca (Ardenna creatopus) mediante análisis de isótopos estables.
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Date
2025
Journal Title
Journal ISSN
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Publisher
Universidad de Concepción
Abstract
La fardela blanca, Ardenna creatopus, es una especie catalogada En Peligro en Chile, nidifica exclusivamente en la Isla Robinson Crusoe y Santa Clara, del Archipiélago de Juan Fernández (33°S, 71°O) y en Isla Mocha (38°S, 73°O). En este estudio se evaluaron las potenciales diferencias en la ecología trófica y distribución espacial entre las tres colonias de la fardela blanca durante los periodos reproductivo y no reproductivo. Para ello, se realizaron análisis de isótopos estables de carbono (δ13C) y nitrógeno (δ¹⁵N) a partir de muestras de sangre (periodo reproductivo) y plumas (periodo no reproductivo) obtenidas entre febrero y marzo de 2024.
Los análisis de los valores de carbono (δ13C) y nitrógeno (δ¹⁵N) mostraron una segregación por el forrajeo entre la colonia de Isla Mocha y las colonias del Archipiélago de Juan Fernández durante el periodo reproductivo. Los individuos de Isla Mocha mostraron valores de δ13C más enriquecidos y un nicho isotópico más reducido, lo que sugiere una preferencia por zonas costeras altamente productivas y una dieta especializada, en comparación con los valores obtenidos para las colonias del Archipiélago de Juan Fernández, los cuales se asocian a un uso de zonas pelágicas y a una dieta más diversa. Por otro lado, durante el periodo no reproductivo, no se detectó segregación entre las colonias. No se encontraron diferencias significativas en los valores de carbono (δ13C) y nitrógeno (δ¹⁵N) entre las colonias, reflejándose en la superposición espacial de las elipses de nicho trófico. Sin embargo, los individuos de Isla Mocha mostraron un aumento considerable del tamaño de nicho isotópico en contraste con los individuos del Archipiélago de Juan Fernández, indicando una mayor plasticidad trófica. Esta expansión podría estar relacionada con diferencias en las rutas migratorias y presas consumidas.
En síntesis, los resultados de este estudio revelan que la fardela blanca presenta una variación en su ecología trófica entre periodos y colonias, lo cual puede tener implicancias ecológicas relevantes, especialmente en las medidas de conservación de esta especie amenazada por impactos antropogénicos.
The Pink-footed Shearwater, Ardenna creatopus, is a species classified as Endangered in Chile. It breeds exclusively on Robinson Crusoe and Santa Clara islands, in the Juan Fernández Archipelago (33°S, 71°W), and on Isla Mocha (38°S, 73°W). This study assessed the potential differences in the trophic ecology and spatial distribution among the three breeding colonies of the Pink-footed Shearwater during the breeding and non breeding periods. For this, stable isotope analyses of carbon (δ¹³C) and nitrogen (δ¹⁵N) were performed using blood samples (breeding period) and feather samples (non-breeding period) collected between February and March 2024. Analyses of δ¹³C and δ¹⁵N values revealed foraging segregation between the Isla Mocha colony and the Juan Fernández colonies during the breeding period. Individuals from Isla Mocha showed enriched δ¹³C values and a narrower isotopic niche, suggesting a preference for highly productive coastal areas and a more specialized diet, in contrast to individuals from the Juan Fernández Archipelago, whose values were associated to more pelagic feeding-areas and a more diverse diet. On the other hand, foraging segregation was not detected among colonies during the non-breeding period. There were no significant differences in δ¹³C or δ¹⁵N values, and the isotopic niche ellipses showed considerable spatial overlap. However, individuals from Isla Mocha exhibited a broader isotopic niche compared to those from Juan Fernández, indicating higher trophic plasticity. This expansion may be related to differences in migratory routes and prey consumption. In summary, the results of this study revealed that the trophic ecology of the Pink-footed Shearwater differs across periods and colonies. This may have relevant ecological implications, particularly for the conservation of this threatened seabird species.
The Pink-footed Shearwater, Ardenna creatopus, is a species classified as Endangered in Chile. It breeds exclusively on Robinson Crusoe and Santa Clara islands, in the Juan Fernández Archipelago (33°S, 71°W), and on Isla Mocha (38°S, 73°W). This study assessed the potential differences in the trophic ecology and spatial distribution among the three breeding colonies of the Pink-footed Shearwater during the breeding and non breeding periods. For this, stable isotope analyses of carbon (δ¹³C) and nitrogen (δ¹⁵N) were performed using blood samples (breeding period) and feather samples (non-breeding period) collected between February and March 2024. Analyses of δ¹³C and δ¹⁵N values revealed foraging segregation between the Isla Mocha colony and the Juan Fernández colonies during the breeding period. Individuals from Isla Mocha showed enriched δ¹³C values and a narrower isotopic niche, suggesting a preference for highly productive coastal areas and a more specialized diet, in contrast to individuals from the Juan Fernández Archipelago, whose values were associated to more pelagic feeding-areas and a more diverse diet. On the other hand, foraging segregation was not detected among colonies during the non-breeding period. There were no significant differences in δ¹³C or δ¹⁵N values, and the isotopic niche ellipses showed considerable spatial overlap. However, individuals from Isla Mocha exhibited a broader isotopic niche compared to those from Juan Fernández, indicating higher trophic plasticity. This expansion may be related to differences in migratory routes and prey consumption. In summary, the results of this study revealed that the trophic ecology of the Pink-footed Shearwater differs across periods and colonies. This may have relevant ecological implications, particularly for the conservation of this threatened seabird species.
Description
Tesis presentada para optar al título de Biólogo/a Marino/a.
Keywords
Aves marinas, Trazadores de isótopos estables, Indicadores ambientales