Parasitic fauna of juveniles of Arapaima gigas (Pisces) in an area of non-natural distribution in the São Paulo State, Brazil

• Grant number: 23/05883-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: August 01, 2023
• End date: July 31, 2024
• Field of knowledge: Biological Sciences - Ecology - Applied Ecology
• Principal Investigator: Igor Paiva Ramos
• Grantee: Fernanda Gabriela Celestino Dias
• Host Institution: Faculdade de Engenharia (FEIS). Universidade Estadual Paulista (UNESP). Campus de Ilha Solteira. Ilha Solteira , SP, Brazil

Abstract

Arapaima gigas (pirarucu), a fish species native to the Solimões-Amazonas and Araguaia-Tocantins River basins in Brazil, is the largest freshwater bony fish from South America. Although it is heavily exploited economically, the species is still classified as "Data Deficient" on the IUCN Red List of Threatened Species. Recently, its occurrence was recorded for the upper Paraná River basin. However, knowledge about its biological attributes in this area is still incipient. Therefore, the objective of this study is to characterize the parasitic fauna of juveniles of A. gigas in an area of non-natural distribution (Grande River, upper Paraná basin, State of São Paulo). For this purpose, at least 30 specimens of A. gigas will, with a maximum size of 50 cm, be analyzed. In the field, the fish will be euthanized, individualized in plastic bags, frozen, and sent to the laboratory, where the standard length (cm) and total mass (g) will be measured. After that, they will have their skin and fins inspected for the presence of encysted parasites. All organs will be removed, isolated, and examined with the aid of a stereomicroscope to collect parasites. The parasites will be processed according to Eiras et al. (2006), morphological and morphometric analyzes will be performed using a computerized image analysis system and taxonomic identifications will be based on the available literature. The component parasite community will be characterized, and the richness and diversity of species will be calculated, as well as the parasitological attributes, prevalence, mean abundance, and mean intensity of infection/infestation for each parasite taxon. Thus, it is expected to provide relevant information about the parasite-host relationships of juveniles of A. gigas in the inland waters of the State of São Paulo.