Mouth gape determines the response of marine top predators to long-term fishery-induced changes in food web structure.

Format: Abstract Send to Sci Rep. 2018 Oct 25;8(1):15759. doi: 10.1038/s41598-018-34100-8. Drago M1, Franco-Trecu V2, Segura AM3,4, Valdivia M4, González EM4, Aguilar A5, Cardona L5. Author information 1 IRBio and Department of Evolutive Biology, Ecology and Environmental Sciences, University of Barcelona, Av. Diagonal 643, 08028, Barcelona, Spain. m.drago@ub.edu. 2 Department of Ecology and Evolution, Faculty of Sciences, Universidad de la República, Iguá 4225, 11400, Montevideo, Uruguay. 3 Modelization and Analysis of Natural Resources (MAREN), Centro Universitario Regional Este (CURE), Universidad de la República, Ruta 9, km 208, 27000, Rocha, Uruguay. 4 National Museum of Natural History (MNHN), 25 de Mayo 582, 11000, Montevideo, Uruguay. 5 IRBio and Department of Evolutive Biology, Ecology and Environmental Sciences, University of Barcelona, Av. Diagonal 643, 08028, Barcelona, Spain. Abstract Here, we analyse changes throughout time in the isotopic niche of the Franciscana dolphin (Pontoporia blainvillei), the South American fur seal (Arctocephalus australis) and the South American sea lion (Otaria flavescens) from the Río de la Plata estuary and adjacent Atlantic Ocean to test the hypothesis that fishing may modify the diet of small-gape predators by reducing the average size of prey. The overall evidence, from stable isotope and stomach contents analyses, reveals major changes in resource partitioning between the three predators considered, mainly because of an increased access of Franciscana dolphins to juvenile demersal fishes. These results are consistent with the changes in the length distribution of demersal fish species resulting from fishing and suggest that Franciscana dolphin has been the most benefited species of the three marine mammal species considered because of its intermediate mouth gape. In conclusion, the impact of fishing on marine mammals goes beyond the simple reduction in prey biomass and is highly dependent on the mouth gape of the species involved. PMID: 30361482 PMCID: PMC6202337 DOI: 10.1038/s41598-018-34100-8 Free PMC Article