Temporal and Ontogenetic Changes in Feeding Ecology of a Characid From Karst Dolines of the Neotropics

ABSTRACT Environmental and biological factors strongly shape fish diets, yet little is known about such influences in flooded Karst Dolines of the Neotropical region. This study examined the diet of Deuterodon luetkenii and assessed its temporal and ontogenetic variation in Lagoa Misteriosa, a karstic lagoon. Fish were sampled bimonthly over 1 year and categorised into two hydrological periods: with algal blooms (WAB) and without algal blooms (AAB). A total of 540 stomachs from four body size classes were analysed, identifying 33 food items. Diet composition varied significantly between periods and among size classes. Filamentous algae and macrophytes were more consumed during the AAB period, while aquatic invertebrates predominated during the WAB period. Niche breadth remained consistent across periods but differed among size classes, indicating ontogenetic dietary shifts. Our findings underscore the ecological role of autochthonous resources and macrophytes in shaping feeding strategies and habitat use in karst ecosystems. Understanding these dynamics is crucial for conservation efforts and for anticipating the potential impacts of environmental changes on trophic interactions within karst environments.