Variações temporais e ontogenéticas na dieta de Piabarchus stramineus (stervadiidae: diapominae) no riacho Cristalina, bacia do rio Dourados

Abstract

Stream ecosystems are spatially heterogeneous and suffer constant anthropogenic impacts that influence the survival of many fish species by reducing available food resources, directly affecting fish fauna dynamics.This study aimed to characterize the diet of Piabarchus stramineus in the Cristalina stream micro-basin and to verify possible temporal and ontogenetic changes in the species' diet. Collections were carried out at six sampling points along a 2nd-order stream belonging to the Dourados River Basin.Food items were analyzed using volumetric methods, calculating the Frequency of Occurrence (O%), Volumetric Frequency (V%), and the Alimentary Index (IAi%). Temporal variation was evaluated between the dry (July–September/2022) and rainy (January–March/2023) periods, and ontogenetic variations were analyzed among four size classes.The diet of P. stramineus was predominantly insectivorous, with emphasis on adult Diptera, Chironomidae, and Formicidae. There was a significant difference between the sampled periods, with higher consumption of adult Diptera and Chironomidae larvae in the dry period, and higher ingestion of adult Diptera and Formicidae in the rainy period. Differences were also observed among the size classes, although without interaction between periods and ontogeny. In lotic environments, assessing the consumed diet and food resources is fundamental to understanding the fish fauna (population dynamics and ecological interactions), reinforcing the importance of the riparian forest for its conservation.