Isotopic niche plasticity in a marine top predator

GUSTAVO COLOMBO; JAVIER CIANCIO; CLAUDIO BURATTI; ESTEBAN FRERE; PABLO YORIO

Viña del Mar

Conferencia; IsoEcol; 2018

Universidad Andres Bello

The Magellanic penguin (Spheniscus magellanicus) breeds in abroad latitudinal range (40-55o S) along the Atlantic and Pacific coasts of SouthAmerica. During breeding, this species is a central-place forager, and feedmainly on schooling fish, with anchovy (Engraulisanchoita) being the dominant prey in the north, and sprats (Sprattus fuegensis) in the south of the Atlanticdistribution. Like most forage species, both species display large recruitment fluctuationsbetween years. We use stable isotope analysis sampled in adult penguin blood fromcolonies in the Atlantic latitudinal range to assess the changes in isotopicniche and trophic level as response of seasonal changes and spatial segregationof forage fish size classes. We found that Magellanic penguin has largeisotopic niche fluctuation during six consecutive reproductive seasons.Furthermore, the size of the isotopic niche negatively correlates with foragefish biomass estimated from accoustic surveys. In addition, the trophic levelof penguins increase with latitude, which correspond to size-distribution ofboth main forage species, showing that penguin from different colonies targetdifferent size classes of its main prey.