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Characterization of Potamotrygon falkneri and Potamotrygon amandae diet (Myliobatiformes, Potamotrygonidae) in unnatural occurrence area in the Upper Paraná river, SP

Grant number: 15/21936-0
Support type:Scholarships in Brazil - Scientific Initiation
Effective date (Start): April 01, 2016
Effective date (End): December 31, 2016
Field of knowledge:Agronomical Sciences - Fishery Resources and Fishery Engineering
Principal Investigator:Igor Paiva Ramos
Grantee:Cibele Diogo Pagliarini
Home Institution: Faculdade de Engenharia (FEIS). Universidade Estadual Paulista (UNESP). Campus de Ilha Solteira. Ilha Solteira , SP, Brazil

Abstract

The Potamotrygonidae form a monophyletic group of the rays belonging to Myliobatiformes order, to represent an important group of Neotropical ichthyofauna, distributed strictly on freshwater environments of South America. However, despite their wide geographical distribution, the establishment of Potamotrygonidae representatives in the upper Paraná River, was only possible after the flood of Salto de Sete Quedas. Thus, dietary knowledge and degree of specialization in the use of food resources of the species of this group are of fundamental importance for understanding the dispersion of these animals by the basin. Thus, the aim of this study is to characterize and compare the diet of two species of rays, Potamotrygon falkneri and Potamotrygon amandae (Myliobatiformes, Potamotrygonidae) and assess the niche breadth of these in unnatural occurrence area in the upper Paraná River. The animals are being collected with the aid of spear, euthanized, measured the disc diameter and length, and total weight. After that, the stomachs are removed and fixed in formaldehyde solution 4%. Stomach contents are being analyzed under stereomicroscope and identified to the lowest possible taxonomic level, being considered as food items. Diet composition is expressed by the feeding index (Fi), using a standardized mass data for the items individually. There will also be comparing the diets of both species through PERMANOVA analysis. Later, with differences between diets, will be used to analyze SIMPER to see which items account for the difference in diet composition between species and the percentage of contribution to the observed difference. To evaluate the niche amplitude will be employed Levin's index for both species. It is hoped that these results expand the knowledge about the diet of species assessed and evaluate the degree of diet specialization, which can contribute to the understanding of successful colonization of reservoirs of the upper Paraná River basin.