Diet composition of juveniles of Arapaima gigas (Pisces) in an area of non-natural distribution in the São Paulo state, Brazil

• Grant number: 23/05915-9
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: August 01, 2023
• End date: July 31, 2024
• Field of knowledge: Biological Sciences - Ecology - Ecosystems Ecology
• Principal Investigator: Igor Paiva Ramos
• Grantee: Vinicius Cesar do Bonfim
• Host Institution: Faculdade de Engenharia (FEIS). Universidade Estadual Paulista (UNESP). Campus de Ilha Solteira. Ilha Solteira , SP, Brazil

Abstract

The introduction of species outside their native range can culminate in processes of biological invasions, which can alter ecological relationships in the new areas of distribution. In the upper Paraná basin, there are ~ 74 species of non-native fish, with the record of the pirarucu Arapaima gigas being one of the most recent. Considering that knowledge about the effects of A. gigas invasion in the receiving basin is still incipient, information about biological aspects that may influence the success of its establishment in the new area is essential to subsidize local management measures for the species, as well as to test fundamental assumptions of the science of biological invasions. In this study, we intend to characterize the composition of the diet of A. gigas in an area of non-natural distribution (Grande River, Upper Paraná River basin, State of São Paulo). For this purpose, 30 specimens of A. gigas with a maximum size of 50 cm were collected in May 2023. The fish were euthanized, and are frozen in the laboratory, where the standard length (cm) and total mass (g) will be measured at the time of analysis. Subsequently, their stomachs will be removed and fixed for analysis, identification, and determination of the mass of food items (gravimetric method), to characterize the diet composition of A. gigas. The diet composition of A. gigas will be expressed by table containing the percentage of mass of each food item in relation to the total mass of food items consumed by all evaluated specimens. Feeding habits will also be determined through the predominance of the type of food resources (e 51% of the total volume consumed by all evaluated specimens). Thus, it is expected to provide relevant information about the predator-prey relationships of juveniles of A. gigas in the inland waters of the State of São Paulo.