Dieta e morfologia como mecanismos estruturadores da assembleia de peixes de seis espécies de characiformes do Córrego Laranja Doce, Dourados, MS

Abstract

The relationship between diet and morphology can reveal important aspects, such as modifications in the feeding habits of species. The objective of this study was to analyze the diet and morphological patterns of six species from an urban stream, to characterize trophic groups and describe their main functional adaptations, as well as to evaluate relationships among feeding habits, morphological traits, and mechanisms of coexistence. The study was conducted at the headwaters of the Laranja Doce stream. Sampling was carried out between 2024 and 2025, and 56 individuals from the order Characiformes were selected. To characterize fish diet, the alimentary index (IAi%) was used, and a Principal Coordinates Analysis (PCoA) was performed based on the composition of dietary items of the species. To quantify morphological attributes, ten ecomorphological indices were used, followed by Principal Component Analysis (PCA) and Redundancy Analysis (RDA). To test for significant differences in diet and morphology among species, ANOVA and PERMANOVA were applied. Diet varied among species across different categories, indicating the use of distinct food resources, ranging from specialized feeding habits, such as the detritivory of Prochilodus lineatus and the aquatic insectivory of Piabina argentea, to more generalist habits, such as the omnivorous behavior of Astyanax lacustris and Psalidodon fasciatus, with a tendency toward insectivory. Oligosarcus pintoi was classified as a terrestrial insectivore, while Piabarchus stramineus was considered a general insectivore. There was partial segregation among species based on dietary item composition. Morphological attributes showed distinct mean values among species and separated species with deep, relatively depressed bodies and large fins—Astyanax lacustris, Prochilodus lineatus, and Psalidodon fasciatus—from species with elongated and hydrodynamic bodies, such as Piabarchus stramineus and Piabina argentea. Oligosarcus pintoi exhibited intermediate characteristics. The analyses highlighted attributes related to locomotion, maneuverability, and microhabitat use. RDA indicated that variation in diet among species can be explained by ecomorphological attributes, evidencing a strong correlation between feeding habits and morphology. This reflects the heterogeneity of resources available in the environment and underscores the importance of their preservation for the local ichthyofauna.