Isotopic niche plasticity in a marine top predator. International Conference on the Applications of Stable Isotope Techniques to Ecological Studies

CIANCIO, J.; YORIO, P.; BURATTI, C.; ALVAREZ COLOMBO, G.; FRERE, E.

Viña del Mar

Conferencia; 11th International Conference on the Applications of Stable Isotope Techniques to Ecological Studies; 2018

Universidad Andres Bello

The Magellanic penguin (Spheniscus magellanicus) breeds in a broad latitudinal range (40-55o S) along the Atlantic and Pacific coasts of South America. During breeding, this species is a central-place forager,and feed mainly on schooling fish, with anchovy (Engraulis anchoita) being the dominant prey in the north, and sprats (Sprattus fuegensis) in the south of the Atlantic distribution. Like most forage species, both species display large recruitment fluctuations between years. We use stable isotope analysis sampled in adult penguin blood from colonies in the Atlantic latitudinal range (350 birds) to assess the changes in isotopic niche and trophic level as response of seasonal changes and spatial segregation of forage fish size classes. We found that Magellanic penguin has large isotopic niche fluctuation during six consecutive reproductive seasons. Furthermore, the size of the isotopic niche negatively correlates with forage fish biomass estimated from accoustic surveys. In addition, the trophic level of penguins increases with latitude, which correspond to size-distribution of both main forage species, showing that penguin from different colonies target different size classes of its main prey.