POPULATION VARIANCE IN PREY AND MACRONUTRIENT SELECTION BY AN ENDANGERED MARINE PREDATOR, THE FRANCISCANA DOLPHIN

DENUNCIO, P; PASO VIOLA, N; MACHOVSKY CAPUSKA, G; RAUBENHEIMER, D; BLASINA, G; GIARDINO, G; MACHADO, R; POLIZZI, P; GERPE, MS; CAPOZZO, HL; DIEGO RODRIGUEZ

Santiago de Chile

Congreso; XI Congreso de la Sociedad Latinoamericana de Especialistas en Mamíferos Acuáticos; 2016

Disentangling the intricacies governing prey selection and dietary breadth in wild predators are important for understandingtheir role in structuring ecological communities and provides critical information for the management and conservation ofecologically threatened species. Here, we combined dietary analysis, nutritional composition analysis of prey, literature dataand nutritional geometry (right-angled mixture triangle models -RMT-) in the most threatened small cetacean in the westernSouth Atlantic Ocean, the franciscana dolphin (Pontoporia blainvillei). Our results demonstrate that franciscanas inhabiting thefourth franciscana management area (FMA IV) used different nutritional mechanisms to adjust their nutritional intake in spiteof living in three different nutritional niches: estuarine, north marine and south marine. Using literature data and RMT modelswe also have found that franciscanas from Rio Grande do Sul (FMA III) have similar macronutrient compositions in the dietsthan marine franciscanas from the IV FMA, whereas northernmost franciscanas (Sao Paulo, FMA II and Rio de Janeiro, FMA I)achieve their nutritional intake through different mechanisms. These findings support previous suggestions on the presenceof three populations within the FMA IV management unit and are vital to interpret the impact of coastal fisheries on this species.It is crucial to better comprehend food selection and dietary needs of the different franciscana