Influência do substrato, sazonalidade e ontogenia na dieta de Cambeva iheringi

Abstract

Aquatic systems harbor complex communities in which substrate heterogeneity, seasonality, and the availability of food resources directly influence trophic structure. This study aimed to determine the diet of Cambeva iheringi, a benthic species from streams of the Corumbataí River basin (upper Paraná River), and to evaluate differences in feeding between streams with Consolidated (CO) and Non-consolidated (NC) substrates, as well as seasonal (rainy and dry periods) and ontogenetic variations. Eleven streams were sampled (six CO and five NC) in the two periods of the year, totaling 22 samplings. To assess ontogenetic variations, individuals were grouped into four size classes. The stomach contents were examined and food items identified to the lowest possible taxonomic level. The diet was characterized using frequency of occurrence, volumetric method, and the Alimentary Index (IAi%). Analyses were based on the volume of food items matrix. A PCoA was performed to visualize the distribution of the diet among the factors (substrate, period, and ontogeny). Differences among factors were tested using PERMANOVA. Trophic niche breadth was assessed using PERMDISP followed by ANOVA. When significant interactions were detected, data were subjected to post hoc tests. A total of 871 C. iheringi individuals were analyzed, and 87 food items were identified. The overall diet was predominantly of aquatic insects, mainly Diptera, Trichoptera, and Ephemeroptera. Significant differences in diet? were observed between substrates and periods. In CO streams, the diet showed greater stability between periods, with variations mainly between Diptera and Trichoptera. In NC streams, Diptera predominated in the diet, and seasonal variation in niche breadth was more pronounced, with a reduction during the dry period. The species also showed ontogenetic differences in diet, with a progressive increase in trophic niche breadth across size classes. Although the diet remained predominantly aquatic insectivorous, variations in the composition and proportions of consumed items demonstrate that more refined taxonomic analyses are essential to reveal ecological patterns hidden by broad classifications. These results reinforce that the diet of benthic species is shaped by the interaction between habitat structure and prey characteristics.